JP4205989B2 - Optical switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical switching device, for example, an optical switching device suitable for use in an intermediate node in a photonic network to which an optical burst switching system is applied.
It is about.
[0002]
[Prior art]
In recent years, it has become necessary to realize a flexible and highly reliable optical network for communication traffic that has increased rapidly due to the rapid expansion of the Internet. For this reason, various networks for optical networks on the premise that routing is performed in wavelength units have been proposed. For example, as shown in FIG. 17, in addition to a point-to-point WDM (Wavelength Division Multiplexing) link (see A in FIG. 17), a wavelength using OADM (Optical Add Drop Multiplexing) or OXC (Optical Cross Connect) A ring network (Ring Network, see FIG. 17B), a mesh network (Mesh Network, see FIG. 17C), etc. that perform routing are proposed.
[0003]
These network technologies use a so-called circuit switching (CS) circuit switching, and transmission in the case of IP-centric data transmission (centering on IP (Internet Protocol)). ineffective.
On the other hand, in so-called optical packet switching (PS; Packet Switching; see E in FIG. 17) in which optical packets are switched as they are, the transmission efficiency of IP data is good, but for highly continuous data, fragmented optical packets are used. Since the ratio occupied by the header is relatively large, the transmission efficiency is degraded. In optical packet switching, packets need to be buffered while the header part is read and routing processing is performed. However, the buffer in the optical region is practically only a fiber delay line, and hardware realization is possible. poor.
[0004]
In view of these technical backgrounds, in constructing a photonic network, which is a network that performs network transfer functions such as transmission, multiplexing, demultiplexing, switching, and routing in the optical domain, based on IP, the above-mentioned CS and PS As an intermediate solution, attention is focused on a network 900 of an optical burst switching system (OBS; Optical Burst Switching, see FIG. 17D) as shown in FIG.
[0005]
FIG. 19 is a schematic diagram illustrating an outline of the OBS network 900 illustrated in FIG. 18, where 910 is an edge node that links the OBS 900 and another access network, and 920 is a core node that configures the OBS 900.
Here, an edge node 910 that constitutes the OBS network 900 includes a multiplexing unit 911 that multiplexes IP traffic from the access network, and a burst for transmitting the multiplexed optical burst signal to the core node 920 side. An assembly (Burst Assembly) 912 is provided.
[0006]
In other words, a burst is a bundle of multiple packets, that is, a multiplex of IP packets from the access network, has an arbitrary data length, and does not have header information. ) Is an intermediate value between the above-described PS and CS (CS <OBS <PS). As a result, it is possible to increase the transmission efficiency of both highly continuous data and highly bursty data.
[0007]
The core node 920 includes a control signal processing unit 921 having an O / E / O conversion unit 921a and a reservation manager 921b, and a wavelength conversion unit (Wavelength Conversion) 922a and an optical switch matrix ( An optical switch matrix) 922b and a data signal processing unit 922 are provided.
[0008]
In other words, the O / E / O conversion unit 921a of the control signal processing unit 921 converts the control optical signal (control packet) corresponding to the header information transmitted on another line into an electric signal, and then the reservation management unit 921b The switch setting process in the optical switch matrix 922b is performed through the routing process in the optical burst signal.
[0009]
In other words, in this OBS network 900, information (control signal) to be added to the head of burst data as header information for routing processing in the intermediate node is separated from the data channel (see A in FIG. 18). (In WDM, transmission is performed using a control channel (see B in FIG. 18) of a burst transmission wavelength and another wavelength). Further, the control signal corresponding to the burst is transmitted by giving an offset (see C in FIG. 18) for the time until the routing processing calculation at the intermediate node is completed, so that the core node 920 omits the installation of the optical buffer. It is possible.
[0010]
The OBS described above is disclosed in detail in Non-Patent Document 1 shown below, for example.
By the way, as a method for controlling the optical switch matrix 922 of the core node 920, it is conceivable to divert a conventional method for a stream signal (circuit switching method). For example, if a three-dimensional MEMS (Micro Electric Mechanical System) is used, there are methods disclosed in Patent Document 1 and Patent Document 2 shown below.
[0011]
In the optical switch control technology disclosed in Patent Document 1 and Patent Document 2, an optimal value corresponding to a path to be connected is previously stored in a memory, and after receiving a connection / switch command, the memory is accessed, The initial value is read out and given to the MEMS mirror, and the drift due to temperature fluctuation is compensated by the optimized feedback control.
[0012]
[Non-Patent Document 1]
C. Qiao et al, “Choice, Features and Issues in Optical Burst Switching”, Optical Network Magazine, pp36-44, Apr. 2000
[0013]
[Patent Document 1]
JP 2002-236264 A
[Patent Document 2]
JP 2003-29171 A
[0014]
[Problems to be solved by the invention]
However, such a conventional optical switch control technique is applied to a transmission apparatus that constitutes an IP-based photonic network (IP over Optical / Photonic), in particular, a transmission apparatus that constitutes an OBS network (core node 920 shown in FIG. 18). When trying to apply, the following three problems to be solved arise.
[0015]
First, as a first problem, when the above-described conventional control method is diverted, there is a problem in increasing the switching time for improving the transmission efficiency.
In optical burst switching, it is necessary to shorten the interval between bursts in order to increase transmission efficiency. That is, in the optical switch, it is necessary to increase the switching time.
[0016]
When the above-described conventional control method is applied, if there is a drift with respect to the read initial value, the optical output power rises slowly by the optimization feedback. If there is such an optical power fluctuation, the O / E converter after passing through the optical switch cannot receive a signal for the time until the power stabilizes, so it becomes difficult to increase the switching time. This hinders the improvement of transmission efficiency.
[0017]
Next, the second problem is that there is a possibility that data collision may occur, which may hinder the improvement of transmission quality.
In other words, when performing optical burst switching or packet switching, burst collision may occur because an autonomous distributed routing processing method is employed. In this case, it is necessary to perform a drop process on the colliding burst in the optical switch. However, it is necessary to prevent a drop in transmission quality by leaking into another path during the drop process. .
[0018]
Furthermore, the third problem is that it is necessary to compensate for fluctuations in the optical output power that may occur due to the resonance characteristics of the switch element in the optical switch and variations in the optical signal power input to the optical switch.
For example, in the case where an optical switch having resonance characteristics is used as a switch element, such as a MEMS mirror, when the resonance component exists in the drive pulse, the time until stabilization, that is, the channel switching time becomes long. Although it is conceivable to remove such a resonance component by using a filter or the like, the rise time as the operation response time is slower than the operation response of the switch element when driven by a very short pulse. Become.
[0019]
Further, since the optical power input to the optical switch for optical burst switching is not always constant, it is difficult to make the output power constant. For this reason, when optical amplification means such as an erbium-doped fiber optical amplifier is used after the optical switch, if there is an input power deviation, the optical amplifier gain is concentrated at a wavelength where the optical input power is large, and the transmission quality is deteriorated. Will be allowed to.
[0020]
For this reason, the optical power input to the optical amplifier needs to be constant between wavelengths. In conventional CS, an optical variable attenuator or the like is inserted to equalize the optical power. When this technique for equalizing optical power is applied to optical burst switching, every time the burst is switched. There is a problem that it is necessary to perform this control, and that it is difficult to make the response speed that makes the optical power uniform follow the high speed of optical burst switching.
[0021]
That is, as an optical variable attenuator, for example, an attenuator that changes phase by applying heat to one arm of a Mach-Zehnder interferometer fabricated on a PLC (Planer Lightwave Circuit) is generally used, but the response is high. It is difficult to apply in optical burst switching which is slow and requires switching in a short time.
[0022]
The present invention has been devised in view of such problems, ensuring a high switching time for improving transmission efficiency and ensuring transmission quality even when data collisions may occur. And providing an optical switching device capable of compensating for variations in optical output power that may occur due to resonance characteristics of the switch element in the optical switch and variations in optical signal power input to the optical switch. Objective.
[0023]
[Means for Solving the Problems]
For this reason, the optical switching device of the present invention has a plurality of input / output ports for inputting or outputting optical signals of a plurality of channels, respectively, and deflecting the optical signal input to the input / output port, thereby And an optical switch having a deflection element for switching the channels, and before the optical signal is input to the optical switch, the deflection state of the deflection element is sequentially set based on the switching control information for the optical signal. In addition, when the optical signal is input to the optical switch, the deflection state of the deflection element is set so that the optical output level of the optical signal is stabilized at the optical output level when the optical signal output is first detected. And a deflection element control section for controlling the above-mentioned (claim 1).
[0024]
Preferably, the deflecting element is configured by a mirror array in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface is arranged, and the deflecting element control unit drives each tilt mirror, and Based on the switching control information on the optical signal, the driving unit that varies the angle of the reflective surface of each tilt mirror, and before the optical signal is input to the optical switch, the reflective surface angle of the corresponding tilt mirror is set. When the optical signal is input to the optical switch, the optical output level of the optical signal is controlled to be stabilized at the optical output level at the time when the optical signal output is first detected. Therefore, a drive control unit that outputs a drive control signal to the drive unit may be provided (claim 2).
[0025]
Further, the drive control unit receives the path setting information for transmitting the optical signal as switching control information for the optical signal input from the input / output port before the optical signal is input to the optical switch. A switching control information receiving unit that performs the setting, and based on the path setting information received by the switching control information receiving unit, the reflection surface angle of the corresponding tilt mirror is sequentially set before the arrival of the optical signal. A setting control unit that outputs a drive control signal to the drive unit, an optical output monitor that monitors the output level of light output from the input / output port of the optical switch, and an output output from the input / output port of the optical switch In order to stabilize the level of the optical signal at the optical output level at the time when the output of the optical signal is confirmed on the optical output monitor, a corresponding tee is provided. A feedback control unit for outputting a second driving control signal for feedback control of the reflective surface angle of Tomira may even be configured to include (claim 3).
[0026]
In addition, the deflecting element has a plurality of mirror arrays in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface are arranged, and optical signals input through the input / output ports are sequentially reflected by the mirror arrays. The optical signal channel is switched, and the setting control unit detects the collision of the optical signal based on the path setting information received by the switching control information receiving unit and the arrival time information and the signal length information. When it is determined that the collision determination unit for determining whether or not the collision occurs and the path to be set next is the same as the previous path determined that the collision of the optical signal has occurred in the collision determination unit, The angle of the reflecting surface of the tilt mirror in the mirror array on the input side is set so that the optical signal input from the plurality of colliding optical signals is dropped. To replace Ri, the drive control signals may be be configured to output to the drive unit (claim 4).
[0027]
In addition, the deflection element control unit controls an optical limiter that resonates the deflection element and controls the output optical power so that the output optical power fluctuates sharply, while removing the optical power fluctuation of the optical signal output from the input / output port of the optical switch. It may be configured (claim 5).
[0028]
DETAILED DESCRIPTION OF THE INVENTION
(A) Description of an embodiment of the present invention
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an optical switching device 100 according to an embodiment of the present invention. The optical switching device 100 shown in FIG. 1 can be applied to the core node 920 of the OBS network 900 shown in FIG. , Optical switch 1, routing processing unit 10, interface unit (IF unit) 20, initial value memory 30, buffer memory 40, drive write control unit 50, drive unit 60, monitor unit 70, FB (Feed back) control unit 80 And a timer 90.
[0029]
In the optical switching device 100 shown in FIG. 1, the optical switch 1, the interface unit 20, the initial value memory 30, the buffer memory 40, the drive writing control unit 50, the drive unit 60, the monitor unit 70, and FB (Feed back). The control unit 80 and the timer 90 have a function as the optical switch matrix 922b in the core node 900 of FIG. 18, and the routing processing unit 10 has a function of the control signal processing unit 921 shown in FIG.
[0030]
The optical switch 1 includes, for example, collimator arrays 2 and 3 as shown in FIG. 2 and two mirror arrays 4 for input and output arranged as a mirror array 4 at an angle of 90 degrees to each other. 1, 4-2.
Further, the input collimator array 2 shown in FIG. 2 collects (collimates) light (optical burst signal) of N (N is a plurality, 8 × 8 in FIG. 2) channel light as a path switching target. N input ports 2a are arranged in an array, and for example, light from a fiber block constituting a bundle of N optical fibers is introduced into each input port 2a and condensed. The emitted light can be emitted to the input mirror array 4-1 side.
[0031]
The input mirror array 4-1 is configured by arranging N tilt mirrors 4a in an array so as to correspond to the arrangement of the input ports 2a of the input collimator array 2 on a one-to-one basis. That is, the input mirror array 4-1 is arranged in an array so that the N tilt mirrors 4a reflect the N collimated lights from the input collimator array 2 to the output mirror array 4-2 at the subsequent stage. Yes.
[0032]
Similarly, the output mirror array 4-2 is configured by arranging N tilt mirrors 4b in an array so as to correspond one-to-one to the arrangement of the tilt mirrors 4a of the input mirror array 4-1. . That is, the output mirror array 4-2 is arranged in an array so that the N tilt mirrors 4b reflect the N reflected lights from the tilt mirror 4a to the output collimator array 3 at the subsequent stage.
[0033]
Further, the output collimator array 3 is configured such that N output ports 3a are arranged in an array so as to correspond one-to-one to the arrangement of the tilt mirror 4b of the output mirror array 4-2, and the tilt mirror 4b. N reflected lights (N-channel optical burst signals after switching) are collimated and output.
[0034]
Further, the tilt mirrors 4a and 4b of the input mirror array 4-1 and the output mirror array 4-2 can be configured as a three-dimensional MEMS mirror (three-dimensional microelectromechanical system mirror). That is, the surface position can be individually varied in the three-dimensional direction with the vertical and horizontal directions of the reflecting surfaces of the mirror arrays 4-1 and 4-2 as axes by driving by the driving unit 60 described later. Thus, the reflected optical path of the incident optical burst signal can be varied.
[0035]
That is, in the input mirror array 4-1 and the output mirror array 4-2 described above, the tilt mirrors 4a and 4b whose surface positions are set cooperate to be input to the input ports 2a of the input collimator array 2. The optical signal is sequentially reflected by the tilt mirrors 4a and 4b of the mirror arrays 4-1 and 4-2, so that the optical signal can be output through the output port 3a at an arbitrary position in the output collimator array 3. Channel switching can be performed.
[0036]
Therefore, the input port 2a of the input collimator array 2 and the output port 3a of the output collimator array 3 function as a plurality of input / output ports for inputting or outputting a plurality of channels of optical signals, respectively, and the input mirror array 4-1 and Each tilt mirror 4a, 4b of the output mirror array 4-2 functions as a deflection element that switches the channel of the optical signal by deflecting the optical signal input to the input port 2a.
[0037]
Each of the tilt mirrors 4a and 4b of the input mirror arrays 4-1 and 4-2 includes a routing processing unit 10, an interface unit 20, an initial value memory 30, a buffer memory 40, and a drive writing control unit shown in FIG. 50, the drive unit 60, the monitor unit 70, the FB control unit 80, and the timer 90 cooperate to perform characteristic surface position control according to the present invention.
[0038]
That is, the routing processing unit 10, the interface unit 20, the initial value memory 30, the buffer memory 40, the drive write control unit 50, the drive unit 60, the monitor unit 70, the FB control unit 80, and the timer 90 generate an optical burst signal. Before inputting to the optical switch 1, the deflection states of the tilt mirrors 4a and 4b are sequentially set based on the switching control information for the optical signal, and when the optical burst signal is input to the optical switch 1, It functions as a deflection element control unit 101 that controls the deflection state of each of the tilt mirrors 4a and 4b so that the level of the burst signal is stabilized at the optical output level when the optical burst signal output is first detected.
[0039]
Here, the drive unit 60 drives each of the tilt mirrors 4a and 4b described above with, for example, an electrostatic force, thereby changing the angle of the reflection surface of each of the tilt mirrors 4a and 4b. Specifically, the degree to which the tilt mirrors 4a and 4b are attracted to the electrodes can be varied by changing the electrostatic capacity charged to the electrodes by an electric signal supplied to the electrodes provided in the vicinity of the tilt mirrors 4a and 4b. Thus, the angle of the reflecting surface is varied.
[0040]
For example, as shown in FIG. 3, each of the tilt mirrors 4a and 4b is supported by a fixed frame (not shown) via a torsion bar 5, and the above-described electrodes are provided near both ends of the tilt mirrors 4a and 4b. 6a and 6b are provided, and by changing the electrostatic capacity charged to the electrodes 6a and 6b by an electric signal from the drive unit 60, the torsion bar 5 supporting the tilt mirrors 4a and 4b is twisted to change the angle of the reflecting surface. .
[0041]
Note that the tilt mirrors 4a and 4b having the above-described configuration are such that the tilt mirrors 4a and 4b have the frequencies shown in Expression (1), where I is the moment of inertia of the tilt mirrors 4a and 4b and k is the spring constant of the torsion bar 4. Although it has the characteristic of resonating at fr, in the present invention, as will be described later, compensation is made for fluctuations in optical output power that may occur due to this resonance characteristic and variations in optical signal power input to the optical switch. Be able to.
fr = (1 / 2π) · √ (k / I) (1) Also, the routing processing unit 10, interface unit 20, initial value memory 30, buffer memory 40, drive write control unit 50, monitor unit 70, FB The control unit 80 and the timer 90 function as a drive control unit that outputs a drive control signal to the drive unit 60.
[0042]
That is, the routing processing unit 10, the interface unit 20, the initial value memory 30, the buffer memory 40, the drive write control unit 50, the monitor unit 70, the FB control unit 80, and the timer 90 are based on the switching control information for the optical burst signal. Thus, before the optical burst signal is input to the optical switch 1, the drive control signal is output to the drive unit 60 so that the reflection surface angles of the corresponding tilt mirrors 4a and 4b are sequentially set. When input to the optical switch 1, the drive control signal is sent to the drive unit 60 in order to control the output level of the optical burst signal to be stabilized at the optical output level when the optical burst signal is first detected. It is designed to output.
[0043]
Here, the routing control unit 10 performs a routing process on the optical burst signal input to the input / output ports 2a and 3a, and includes an O / E / O (Optic / Electric / Optic) conversion unit 11 and a reservation. A management unit 12 is provided.
Here, the O / E / O conversion unit 11 serving as a switching control information receiving unit converts light having a wavelength provided for the control channel common to the N channel to which the optical burst signal is transmitted, into each optical burst signal. The switching control information is received as a modulated optical control signal (control packet) and converted into an electrical signal, and the switching control information corresponding to the optical burst signal after switching is output to the transfer destination node as a similar optical control packet signal. To do.
[0044]
That is, the O / E / O conversion unit 11 uses the optical burst signal as the switching control information for the optical burst signal input from the input port 2a of the optical switch 1 together with the path setting information for transmitting the optical burst signal. A control packet including arrival time information and signal length information of the signal to the optical switch 1 is received before the optical burst signal is input to the optical switch 1.
[0045]
In addition, the reservation management unit 12 determines a setting change in the optical switch 1 based on the routing information input from the O / E / O conversion unit 11, and interfaces the switching information based on the determined setting change content. This is output to the unit 20, and comprises the same route determination unit 12A and the collision determination unit 12B. Further, the interface unit 20 interfaces the switching control information from the routing control unit 10, and path setting information (optical path information) forming the switching control information is output to the initial value memory 30 and the optical burst. Information relating to the arrival time of the signal (burst start time) and the signal length (burst length) is output to the timer 90.
[0046]
The initial value memory 30 stores information (drive amount data) regarding the drive amount for each tilt mirror 4a, 4b corresponding to the path setting that can be set in the optical switch 1 as initial value information. The buffer memory 40 temporarily holds drive amount data for the tilt mirrors 4a and 4b corresponding to the path setting information output from the interface unit 20 to the initial value memory 30.
[0047]
Further, the drive writing control unit 50 uses the optical burst signal input end detection information from the timer 90 and the drive amount data for the tilt mirrors 4a and 4b held in the buffer memory 40 based on the detection information. A drive writing control signal (drive control signal) for controlling the drive unit 60 that drives the switch 1 is output.
Furthermore, the timer 90 determines the timing at which the input of the optical burst signal is completed based on the arrival time information and signal length information of the optical burst signal received by the O / E / O converter 11 to the optical switch 1. It functions as an input end timing detection unit to detect. That is, the time is measured with the input time point of the optical burst signal to the optical switch 1 as the start point, and the input end time point according to the signal length information is detected. To output.
[0048]
Thereby, in the drive writing control unit 50, when the end timing of the optical burst signal input previously input is detected by the timer 90, the feedback control in the FB control unit 80 described later is temporarily stopped, Drive amount data for setting the path of an optical burst signal to be input (scheduled to be input) held in the buffer memory 40 is immediately supplied to the drive unit 60 by the drive write control unit 50. Drive writing control is performed.
[0049]
FIG. 4 is a time chart for explaining the operation when the timer 90 detects the end timing of optical burst signal input.
In optical burst switching, an optical control packet signal having switching control information for the next optical burst signal may arrive at the O / E / O converter 11 even during the routing of the optical burst signal. For example, while the optical burst signal (burst B1) is being routed between time t4 and time t9 in FIG. 4, the optical control packet signal (control packet) for the next optical burst signal (burst B2) during that time. ) Arrives (see time points t5 to t6 in FIG. 4).
[0050]
In this case, in order to switch the tilt mirrors 4a and 4b for the next optical burst signal (burst B2) in a short time, the reservation manager 12 calculates the optical path information calculated from the control packet signal for the burst B2. Are transferred to the interface unit 20 in advance, and an initial value corresponding to the optical path is read from the initial value memory 30 and stored in the buffer memory 40.
[0051]
Then, in order to accurately grasp the end time of the previous burst, the interface unit 20 gathers the arrival time information and the signal length information of the optical burst signal to the optical switch 1 together with the optical path information. The time during which the burst signal passes through the optical switch 1 is checked. When the end of the burst signal is confirmed, the initial value is read from the buffer memory 40, and the tilt mirrors 4a and 4b are immediately driven and controlled.
[0052]
For example, after the burst B1 shown in FIG. 4 is input to the O / E / O conversion unit 11 (see time points t0 to t1), an optical switching control signal (optical) output from the reservation management unit 12 as an output of the routing processing unit 10 When the switching control information is output (see time points t2 to t3), the timer 90 starts the timer count with the input of the switching control information as a trigger (see time point t3).
[0053]
After the tilt mirrors 4a and 4b are driven by the drive unit 60 and the reflection surface position of the tilt mirrors 4a and 4b is set to an angle corresponding to the drive amount data stored in the initial value memory 30, the burst B1 is input. However, the timer 90 detects the end point of the input of the burst B1 based on the count value (see time point t7).
[0054]
When the timing at the end of input of the burst B1 is received from the timer 90, the drive write control unit 50 reads the drive amount data for the burst B2 already stored in the buffer memory 40, and immediately, the tilt mirror 4a and 4b are driven and controlled.
As a result, the setting of the tilt mirrors 4a and 4b for the optical burst signal to be subsequently input is started from the time when the input of the previous optical burst signal is completed, whereby the burst B2 is input ( Preparation of setting of the optical switch 1 that must be completed in the previous stage can be started early.
[0055]
Therefore, based on the route setting information received by the O / E / O conversion unit 11 by the reservation management unit 12, the interface unit 20, the initial value memory 30, the buffer memory 40, the drive write control unit 50, and the timer 90 described above. Then, before the arrival of the optical burst signal, setting is made to output the first drive control signal as the drive writing control signal for sequentially setting the reflection surface angles of the corresponding tilt mirrors 4a and 4b to the drive unit 60. The control unit is configured.
[0056]
Further, the reservation management unit 12, the interface unit 20, the initial value memory 30, the buffer memory 40, and the drive writing control unit 50 set the path for the optical burst signal before the optical burst signal is input to the optical switch 1. Based on the information, the change state of the tilt mirrors 4a and 4b is set, and at the input end timing of the optical burst signal detected by the timer 90, the tilt mirror 4a and 4b are tilted based on the path setting information of the optical signal to be subsequently input. It functions as a deflection state switching unit that outputs a drive control signal to the drive unit 60 in order to start switching the deflection states of the mirrors 4a and 4b.
[0057]
The monitor unit 70 functioning as an optical output monitor monitors the level of the optical burst signal output from the output port 3a in the optical switch 1, and includes, for example, N photodiodes for every N output ports. Can be configured.
Further, the FB control unit 80 outputs a feedback control signal to the drive unit 60 based on the level of the optical burst signal detected by the monitor unit 70 so as to stabilize the level of the optical burst signal. However, the target level for stabilizing the optical burst signal is set to a characteristic level according to the present invention.
[0058]
Specifically, the level of the optical burst signal output from the output port 3a in the optical switch 1 is stabilized at the optical output level when the output of the optical burst signal is first confirmed by the monitor unit 70. As described above, the reflection surface angles of the corresponding tilt mirrors 4a and 4b are feedback-controlled. Thereby, a constant optical output power can be obtained from the head of the optical burst signal.
[0059]
For example, if the output of the corresponding optical burst signal is first confirmed at the time T2 after the tilt mirrors 4a and 4b are switched at the time T1 shown in FIG. 5, the optical output level at the time T2 is changed. As a target, the FB controller 80 performs feedback control on the drive unit 60.
[0060]
In this respect, the time point at which the light output level reaches the highest level at time T3 after time t1 has elapsed from time T2 without setting the light output level at time T2 as the target is set as the target for stabilization control in the FB controller 80. Compared to the case, the time required for stabilizing the light output level can be significantly reduced by the time t1.
[0061]
FIG. 6 is a flowchart for explaining an example of the optical level control when the conventional circuit switching is performed using the optical switch, and corresponds to the optical level control targeting the optical output level at the time point T3 described above. To do. On the other hand, FIG. 7 shows the optical switching device 100 in the case where the optical output level at the time when the output of the optical burst signal is first confirmed at the above-mentioned time T2 is set as the target of the stabilization control in the FB controller 80. It is a flowchart for demonstrating operation | movement of.
[0062]
As shown in FIG. 6, in the case where wavelength switching in the nodes constituting the CS network is performed by an optical switch, since there is a premise that there is an optical input, when a switching command is received (step S1), After initial setting of the tilt mirror (steps S2 and S3), stabilization control is applied while watching the monitored power. That is, when the monitored power value becomes maximum (steps S4 to S6), the maximum optical power is stabilized so as not to fluctuate within a specified value (steps S7 to S9).
[0063]
On the other hand, when performing wavelength switching in an IP-based photonic network, particularly an OBS network, it is necessary to complete the setting of the tilt mirrors 4a and 4b before the arrival of the optical burst signal.
When the control for finding the peak as shown in FIG. 6 is applied after the monitor power is detected, power fluctuation occurs after the optical burst signal is input. This makes it difficult to identify the signal in the optical burst receiver (see reference numeral 922a in FIG. 18) following the optical switch 1, and eventually increases the extra time for routing the optical burst signal.
[0064]
Therefore, when performing wavelength switching in the OBS network, as shown in FIG. 7, after receiving a switching command (step S1), after initial setting of the tilt mirror as a switch element (step S2, step S3) ) First, the optical output level at the time when the output of the optical burst signal is confirmed (step S41) is set as a target for stabilization control in the FB controller 80 (step S42), and the optical power set as the target is a specified value. (Steps S71, S81, S9). This prevents power fluctuations from occurring after the optical burst signal is input.
[0065]
By the way, the same route determination unit 12A of the reservation management unit 12 sets the route (previous route) set for the preceding optical burst signal based on the route setting information received by the O / E / O conversion unit 11. And the path to be set (the path to be set next) for the optical burst signal to be input later is determined. In the reservation management unit 12, when the same route determination unit 12 determines that the previous route and the next route to be set are the same, route setting information for controlling the deflection state of the tilt mirrors 4a and 4b. Is prevented from being output, the deflection state of the tilt mirrors 4a and 4b can be maintained.
[0066]
Furthermore, the collision determination unit 12B of the reservation management unit 12 uses the optical signal based on the path setting information received by the O / E / O conversion unit 11, and the arrival time information and signal length information of the corresponding optical burst signal. It is determined whether or not a collision occurs.
Specifically, in the collision determination unit 12B, based on the path setting information, the path set for the preceding optical burst signal (previous path) and the optical burst signal to be input later If it is determined that a later optical burst signal will arrive during the input of the preceding optical burst signal, based on the arrival time information and the signal length information, It is determined that a collision of optical signals occurs.
[0067]
FIG. 8 is a flowchart for explaining the processing of the collision determination unit 12B described above. As shown in FIG. 8, the control for the burst B from the channel #B is performed during the routing for the burst A from the channel #A. When the packet arrives at the routing processing unit 10 (step P1), the above-described burst A collides with the burst B input next to the burst A in the collision determination unit 12B of the reservation management unit 12 in the routing processing unit 10. (Step P2 to Step P4).
[0068]
That is, the collision determination unit 12 checks the port number of the output port 3a corresponding to the destination of the burst B based on the route setting information obtained from the control packet for the burst B (step P2).
At this time, if the port number of the output port 3a that is the destination of the burst B is different from the port number of the output port 3a that is the destination of the burst A, the collision determination unit 12B determines that the burst A and the burst B are It is determined that no collision occurs, and a path for burst B is set by driving the tilt mirrors 4a and 4b in the optical switch 1 regardless of whether or not the burst A is being routed (step P3). From the NO route of step P5).
[0069]
Further, when the port number of the output port 3a that is the destination of the burst B is the same as the port number of the output port 3a that is the destination of the burst A, the collision determination unit 12B next uses the control packet of the burst B. Based on the arrival time information of the burst B obtained and the arrival time information and signal length information of the burst A obtained from the control packet of the burst A, the arrival time of the burst B is larger than the time when the input of the burst A ends. It is determined whether or not it is before (from the YES route of step P3 to step P4).
[0070]
Here, when the arrival time of burst B is later than the time when the input of burst A ends, collision determination unit 12B determines that there is no collision between burst A and burst B. Thus, based on the switching control information output from the routing processing unit 10, the setting of the optical switch 1 for the burst B is written from the initial value memory 30 to the buffer memory 40, and the timer count by the timer 90 is also performed. At the same time, the setting of the optical switch 1 for the burst B (path setting) is performed from the end of the input of the burst A (from the NO route of the step P4 to the step P6).
[0071]
When the arrival time of burst B is before the time when the input of burst A ends, the collision determination unit 12B determines that burst A and burst B will collide.
For example, as shown in FIG. 9, when control packet Cb of burst B from channel #B is input (see time t1 in FIG. 9), collision control unit 12B performs switching control obtained from this control packet. Based on the information, the output port 3a that is the destination of the burst B is the output port of the same port number #X as the burst A, and the arrival time of the burst B (see time t2 in FIG. 9) is If the time is before the input end time (see time t3 in FIG. 9), a collision occurs between the times t2 and t3.
[0072]
As described above, when the collision determination unit 12B determines that the burst A and the burst B collide, a burst B drop command is output. Specifically, switching control information that reflects the optical burst signal as the burst B in a direction not to be output to the output port 3a given as the route setting information is output (step P7).
[0073]
When the switching control information as such a drop command is output in the routing processing unit 10, the tilt mirror 4 a in the optical switch 1 is driven to drop the optical burst signal (burst B) in the buffer memory 40. Quantity data is extracted from the initial value memory 30 and held. Thereby, the tilt mirror 4a of the optical switch 1 is driven in the drive unit 60 through the control of the drive writing unit 50 (step P8).
[0074]
For example, when the optical switch 1 is driven by the drive unit 60, as shown in FIG. 10, the burst B outputs the surface position of the tilt mirror 4a that is a deflection element in the input side mirror array 4-1 of the optical switch 1. If the angle is set so as not to be reflected by the side mirror array 4-2, the burst B can be dropped while sufficiently suppressing the occurrence of crosstalk in other channels.
[0075]
By the way, when driving the tilt mirrors 4a and 4b in the drive unit 60 described above, an electric signal that changes the surface position of the tilt mirrors 4a and 4b by a predetermined amount based on the control from the drive writing control unit 50. In the case where the resonance frequency is included in this electrical signal, the light of the optical burst signal output from the output port 3a of the optical switch 1, for example, as indicated by Q2 in FIG. In the power, a light level fluctuation caused by the resonance frequency fr occurs.
[0076]
In the optical switching device 100 according to the present embodiment, the drive signal (electrical signal) from the drive unit 60 has a steep rise time and positively includes the resonance frequency component shown in the above formula (1). It is driven by a pulse signal.
As a result, even when the stabilization control by the FB control unit 80 is performed, the optical power of the optical burst signal output from the output port 3a of the optical switch 1 is changed to, for example, as indicated by Q2 in FIG. Will cause fluctuations in the light level due to the resonance frequency fr. That is, the light level varies up and down around the light level that becomes the target PT of feedback control by the FB control unit 80 described above.
[0077]
However, although the resonance frequency fr component is positively included in the drive pulse signal and the tilt mirrors 4a and 4b are driven, the optical power fluctuation of the output optical burst signal occurs, but as shown in FIG. A relatively high gain can be ensured as compared with a drive pulse signal that does not include a resonance frequency component.
Further, as shown in FIG. 13, for example, as shown in FIG. 13, an optical limiter amplifier 7 for removing a resonance frequency component of a high level optical burst signal rising at a high speed obtained by the drive pulse signal as described above is provided at the subsequent stage of the optical switch 1. As a result, the resonance frequency component of the output optical burst signal from the optical switch 1 can be reliably cut off while making the level of the output optical burst signal as high as possible. Yes.
[0078]
FIG. 11A shows the input / output characteristics of the optical limiter amplifier, and FIG. 11C shows the time response characteristics of the output of the optical limiter amplifier. Here, as shown in Q1 of FIG. 11A, the optical limiter amplifier 7 linearly transmits the input from the output light zero level to the lower limit level PL constituting the resonance component of the output light burst signal. On the other hand, the resonance frequency component of the output optical burst signal from the optical switch 1 is cut by setting the input / output level characteristics so that the input of the component exceeding the lower limit level PL of the resonance component is a constant level output. It can be turned off.
[0079]
Further, since the response characteristic of the optical limiter amplifier 7 constituted by this semiconductor laser amplifier can be made sufficiently faster than the response characteristic of the optical switch 1, as shown by Q4 in FIG. Optical power can be made uniform, and the surface position of the tilt mirrors 4a and 4b can be switched (that is, the path can be switched) at high speed. In addition, it is possible to eliminate the need for optical power control every time the burst is switched, and to make the optical level variation output from each output port 3a uniform.
[0080]
In this regard, when the optical limiter amplifier 7 is not used, since it is necessary to drive the tilt mirrors 4a and 4b while suppressing the resonance, the drive unit 60 outputs an optical output as indicated by Q3 in FIG. It is necessary to use a drive signal that gradually increases the level until time t3 until the level is stabilized at the target level. That is, t3 (> t1) is required as the time for switching the surface position (time until the surface position is stabilized).
[0081]
Note that Q5 in FIG. 11C is a time for switching the surface position when the optical limiter amplifier 7 is applied when the output of the optical switch 1 is obtained as in Q3 of FIG. 11B. This indicates that a time t2 having a value between t1 and t3 is necessary.
In the present embodiment, the switching time is controlled by the above-described FB control unit 80 by providing the optical limiter amplifier 7 in the subsequent stage of the optical switch 1 while using the steep driving pulse signal including the resonance frequency as described above. In addition to the shortening action, the influence of the resonance frequency component can be suppressed, the switching time can be increased, and a stable switching operation can be obtained.
[0082]
Further, after the optical level of the optical burst signal of each channel is equalized by the optical limiter amplifier 7 described above, when transmitting the optical burst signal to the destination side apparatus through the optical fiber, the optical amplifier is used as necessary. 9 is amplified before transmission. At this time, since the light level of each wavelength component is made uniform by the optical limiter amplifier 7, the optical amplifier 9 can also amplify each wavelength component to a uniform level.
[0083]
That is, when the power distribution of the optical burst signal of each wavelength input to the optical switch 1 varies as shown in FIG. 14A, stabilization control is performed by the FB control unit 80. Even in this case, it is assumed that the power distribution of the optical burst signal of each wavelength output from the optical switch 1 also varies as shown in FIG.
[0084]
At this time, the power distribution of the optical burst signal of each wavelength can be adjusted to a uniform level as shown in FIG. 14C by the optical power amplifier 7 provided in the subsequent stage of the optical switch 1.
Further, even if a loss occurs and the overall optical power is reduced when the light combined with the light of each wavelength is output from the multiplexer 8 at the subsequent stage of the optical limiter amplifier 7, Since the uniformity of the optical power distribution can be substantially maintained (see (d) of FIG. 14), if the output of the multiplexer 8 is amplified by the optical amplifier 9, each wavelength component is uniformly amplified, The output power of each wavelength in the amplified output optical burst signal is also uniform [see (e) of FIG. 14].
[0085]
In this regard, when the optical limiter amplifier 7 is not provided in the subsequent stage of the optical switch 1, as shown in (a) of FIG. 15, the optical power distribution of each wavelength in which the variation has occurred remains unchanged. Output from the optical switch 1 (see FIG. 15B), multiplexed by the multiplexer 8 (see FIG. 15C), and amplified by the optical amplifier 9 (see FIG. 15D). ]. Since the optical power distribution of each wavelength amplified by the optical amplifier 9 is non-uniform, the gain is concentrated on the power having a large power, so that the dispersion of the power distribution becomes more conspicuous and the transmission quality is improved. It can be a hindrance.
[0086]
Therefore, the optical limiter amplifier 7 can make the power distribution of each wavelength uniform and improve the transmission quality.
With the above-described configuration, in the optical switching device 100 according to the embodiment of the present invention, the tilt mirrors 4a and 4b of the optical switch 1 are controlled as follows to switch the channel of the input optical burst signal. Output with a stable optical output power.
[0087]
First, in the optical switching device 100, an O / E / O conversion unit 11 of the routing processing unit 10 receives an optical control signal (control packet) at an optical wavelength set for receiving control information. In addition to the path setting information for one optical burst signal input to the input port 2a of the optical switch 1, this control packet includes arrival time information and signal length information for the optical burst signal ( (See the first step R1 in FIG. 16).
[0088]
When the above-described control packet is received by the O / E / O conversion unit 11, before the optical burst signal is input to the optical switch 1, based on the path setting information received in the first step R1, the optical packet is transmitted. The deflection states of the tilt mirrors 4a and 4b of the switch 1 can be set sequentially (see the second step R2 in FIG. 16).
[0089]
The tilt mirrors 4a and 4b are set by the reservation management unit 12, the interface unit 20, the initial value memory 30, the buffer memory 40, the drive write control unit 50, the drive unit 60, and the timer 90 as described above. Done by working.
Further, in the second step R1, whether or not a plurality of optical signals scheduled to be input to the optical switch 1 collide is determined in the collision determination unit 12B of the reservation management unit 12 by setting the path for each optical signal. Determination is made based on the information, arrival time information and signal length information (collision determination step).
[0090]
When the collision determination unit 12B determines that the plurality of optical burst signals scheduled to be input collide with each other, the first one of the plurality of optical burst signals is scheduled to be input to the input / output port 2a. The tilt states of the tilt mirrors 4a and 4b are set so as to drop the optical burst signal other than the optical burst signal, thereby preventing the occurrence of crosstalk of the optical burst signal output from the optical switch 1 (drop setting). Step).
[0091]
In the second step, when two optical burst signals scheduled to be input to the optical switch 1 have conflicting path settings based on the path setting information even if the input times do not overlap (for example, the switching destination) When the channels of the optical burst signal overlap, the timer 90 counts the input end point of the optical burst signal input first, and at the same time, the drive amount data for switching control for the next optical burst signal. Are switched so that the next optical burst signal can be switched immediately after the input of the previous optical burst signal is completed.
[0092]
Further, in the same path determination unit 12A, when the path setting information of the optical burst signals to be input before and after is the same, that is, when the settings of the input channel and the output channel are the same, the interface unit 20 has a special feature. Thus, the path setting for the optical burst signal input before is used as it is for routing of the optical burst signal input later.
[0093]
As described above, before the optical burst signal is input, the tilt mirrors 4a and 4b for channel switching (routing) are set for the optical burst signal. Input to the input port 2a.
At this time, the optical output level of the optical burst signal is monitored by the monitor unit 70, and the FB control unit 80 tilts so that the optical output level is stabilized at the time when the optical burst signal output is first detected. The deflection state of the mirrors 4a and 4b is controlled (see the third step R3 in FIG. 16). Thereby, stabilization control from the first bit of the optical burst signal can be achieved.
[0094]
In the second step R2, the resonance frequency component of the tilt mirrors 4a and 4b is used as a drive signal (electric signal) supplied from the drive unit 60 for controlling the surface position of the tilt mirrors 4a and 4b. A pulse signal in which the optical output power fluctuates sharply while being actively included.
With such a drive signal, the power of the optical burst signal output from the output port 3a of the optical switch 1 can be increased, but fluctuations in the optical output power can occur. However, by removing the optical power fluctuation of the optical burst signal output from the output port 3a with an optical limiter amplifier (see the fourth step in FIG. 16), the optical output power fluctuation that can occur in the second step R2 is eliminated. The level of the output optical burst signal is stabilized.
[0095]
Thus, according to the optical switching device 100 according to the embodiment of the present invention, the routing processing unit 10, the interface unit 20, the initial value memory 30, the buffer memory 40, and the drive writing control unit as the deflection element control unit 101. 50, the drive unit 60, the monitor unit 70, the FB control unit 80, and the timer 90 can stabilize and control the optical level from the first bit of the optical burst signal. Therefore, in the device on the side receiving this optical burst signal In addition, it is possible to stably receive a signal from the first bit position.
[0096]
Further, the switching time of the optical switch 1 needs to be considered as the time until the surface position of the tilt mirrors 4a and 4b is switched by giving the driving amount data as an initial value. Since this switching time can be regarded as equivalent to the time until the tilt mirrors 4a and 4b respond by giving the driving amount data as an initial value, it is necessary to increase the transmission efficiency in the optical burst switching. Fast switching characteristics can be secured.
[0097]
In addition, when the timer 90 is provided, for the two optical burst signals scheduled to be input to the optical switch 1, even when the path setting based on the path setting information competes until the input times do not overlap, By counting the time when the input of the optical burst signal input first by the timer 90 is counted, the switching operation of the next optical burst signal can be performed immediately after the input of the previous optical burst signal is completed. Thus, there is an advantage that the switching time of the optical path by driving the tilt mirrors 4a and 4b can be increased.
[0098]
Further, when the same path determination unit 12A has the same path setting information of the optical burst signals that are scheduled to be input before and after, the special switching control information is not output to the interface unit 20 in advance. Since the path setting for the input optical burst signal is used as it is for the routing of the optical burst signal input later, the switching time of the optical path can be increased as in the above case. I can expect.
[0099]
Further, when the collision determination unit 12B determines that a plurality of optical burst signals scheduled to be input collide, the optical burst scheduled to be input to the input / output port 2a first among the plurality of optical burst signals. Since the tilt states of the tilt mirrors 4a and 4b are set so as to drop the optical burst signal other than the signal, the occurrence of crosstalk of the optical burst signal output from the optical switch 1 is prevented, and the transmission quality is improved. There is an advantage that can be achieved.
[0100]
Further, in the drive unit 60, the tilt mirrors 4a and 4b are driven to resonate and the output optical power varies sharply, while removing the optical power variation of the optical signal output from the output port 3a of the optical switch 1. Since the optical limiter amplifier 7 is provided, the optical output power fluctuation caused by the resonance frequency of the tilt mirrors 4a and 4b can be surely removed, the level of the output optical burst signal can be stabilized, and the optical path can be switched. There is also an advantage that the time can be increased.
[0101]
(B) Other
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the optical switching device 100 applied to an OBS network that performs optical burst switching has been described in detail. However, according to the present invention, the optical switching device is not limited thereto. For example, the present invention can be similarly applied to a switching method that realizes an IP-based photonic network such as optical packet switching.
[0102]
Further, in the above-described embodiment, a MEMS mirror switch is applied as the optical switch 1, but according to the present invention, the present invention is not limited to this, and it is of course possible to apply to an optical switch other than MEMS. .
In addition, if each embodiment of this invention is disclosed, it can be manufactured by those skilled in the art.
[0103]
(C) Additional notes
(Supplementary note 1) A deflecting element that switches a channel of the optical signal by deflecting the optical signal input to the input / output port together with a plurality of input / output ports for inputting or outputting the optical signal of the plurality of channels. An optical switch with
Before the optical signal is input to the optical switch, the deflection state of the deflection element is sequentially set based on the switching control information for the optical signal, and when the optical signal is input to the optical switch, A deflection element control unit configured to control the deflection state of the deflection element so that the optical output level of the signal is stabilized at the optical output level at the time when the optical signal output is first detected. The
An optical switching device.
[0104]
(Supplementary note 2) The deflection element is constituted by a mirror array in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface are arranged,
The deflection element controller
A drive unit that drives each tilt mirror to change the angle of the reflection surface of each tilt mirror;
Based on the switching control information for the optical signal, before the optical signal is input to the optical switch, the reflecting surface angle of the corresponding tilt mirror is sequentially set, and the optical signal is input to the optical switch. Then, in order to control the optical output level of the optical signal to be stabilized at the optical output level at the time when the optical signal output is first detected, a drive control unit that outputs a drive control signal to the drive unit; ,
The optical switching device according to appendix 1, characterized by comprising:
[0105]
(Appendix 3) The drive control unit
A switching control information receiving unit for receiving path setting information for transmitting the optical signal as switching control information for the optical signal input from the input / output port before the optical signal is input to the optical switch; ,
Based on the path setting information received by the switching control information receiving unit, a first drive control signal for sequentially setting the reflection surface angle of the corresponding tilt mirror before arrival of the optical signal is supplied to the driving unit. A setting control unit to output to
An optical output monitor for monitoring the output level of light output from the input / output port of the optical switch;
In order to stabilize the level of the optical signal output from the input / output port of the optical switch at the optical output level when the output of the optical signal is confirmed by the optical output monitor, A feedback control unit that outputs a second drive control signal for feedback control of the reflection surface angle;
The optical switching device according to appendix 2, characterized by comprising:
[0106]
(Supplementary Note 4) The switching control information receiving unit receives, as the switching control information, arrival time information and signal length information of the optical signal to the optical switch together with the path setting information before arrival of the optical signal. While configured to
The setting control unit
Based on the arrival time information and signal length information received by the switching control information receiving unit, an input end timing detection unit that detects a timing at which the input of the optical signal ends;
Before the optical signal is input to the optical switch, the deflection state of the deflection element is set based on path setting information about the optical signal, and the optical signal detected by the input end timing detection unit A deflection state switching unit that outputs the drive control signal to the drive unit so as to start switching the deflection state of the deflection element based on the path setting information of the optical signal to be subsequently input,
The optical switching device according to appendix 3, characterized by comprising:
[0107]
(Supplementary Note 5) The setting control unit
Based on the route setting information received by the switching control information receiving unit, the same route determination unit for determining whether the previous route and the route to be set next are the same, or
Appendix 3 wherein the same path determination unit is configured to hold the deflection state of the deflection element when it is determined that the previous path and the path to be set next are the same. Optical switching device.
[0108]
(Supplementary Note 6) The deflection element has a plurality of mirror arrays in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface are arranged, and optical signals input through the input / output ports are sequentially reflected by the mirror arrays. Is configured to switch the channel of the optical signal,
The setting control unit
A collision determination unit for determining whether or not a collision of optical signals occurs based on the route setting information received by the switching control information reception unit and the arrival time information and the signal length information, and
When it is determined by the collision determination unit that the previous path determined to cause an optical signal collision and the path to be set next are the same, the signal is input after the optical signals that collide. Appendix 3 wherein the drive control signal is output to the drive unit so as to switch the reflection surface angle of the tilt mirror in the mirror array on the input side so as to drop the optical signal. Optical switching device.
[0109]
(Supplementary note 7) The optical switching device according to supplementary note 1, wherein the deflection element is constituted by a three-dimensional microelectromechanical system mirror.
(Supplementary Note 8) While the deflection element control unit controls the deflection element to resonate and the output light power fluctuates sharply,
2. The optical switching device according to appendix 1, characterized by comprising an optical limiter that removes optical power fluctuations of the optical signal output from the input / output port of the optical switch.
[0110]
(Supplementary note 9) The optical switching device according to supplementary note 8, wherein the optical limiter includes a semiconductor laser amplifier.
(Supplementary Note 10) A deflecting element that switches a channel of the optical signal by deflecting the optical signal input to the input / output port together with a plurality of input / output ports for inputting or outputting the optical signal of a plurality of channels. An optical switch control method for controlling a deflection state in the deflection element, the optical switch comprising:
A first step of receiving path setting information about an optical signal input to the input / output port before the optical signal is input to the input / output port;
A second step of sequentially setting the deflection state of the deflection element based on the path setting information received in the first step before the optical signal is input to the input / output port;
When the optical signal is input to the optical switch, the deflection state of the deflection element is controlled so that the optical output level of the optical signal is stabilized at the optical output level at the time when the optical signal output is first detected. The third step to
A method for controlling an optical switch, which is characterized.
[0111]
(Supplementary Note 11) In the first step, the arrival time information and the signal length information of the optical signal together with the path setting information about the optical signal are received before the arrival of the optical signal,
The second step is
A collision determination step of determining whether or not a plurality of optical signals to be input to the optical switch collide based on the path setting information, arrival time information and signal length information for each optical signal;
In the collision determination step, when it is determined that the plurality of optical signals collide, an optical signal other than the optical signal scheduled to be input to the input / output port first is dropped among the plurality of optical signals. The control method for an optical switch according to appendix 10, characterized by comprising a drop setting step for setting the deflection state of the deflection element as described above.
[0112]
(Supplementary note 12) In the second step, when setting the deflection state of the deflection element, the deflection element is controlled to resonate and the output optical power fluctuates sharply.
Under the control of the third step, the optical switch is configured to include a fourth step of removing the optical power fluctuation of the optical signal output from the input / output port of the optical switch by an optical limiter amplifier. The control method of the optical switch of Additional remark 10 or 11.
[0113]
【The invention's effect】
As described above in detail, according to the optical switching device of the present invention, the light level can be stabilized and controlled from the first bit of the optical signal by the deflection element control unit. Also in the apparatus, it is possible to stably receive a signal from the first bit position. As the switching time of the optical switch, it is necessary to consider the time until the deflection element is switched by giving the driving amount data as an initial value. However, the deflection element control unit described above sets this switching time as the initial value. Therefore, the high-speed switching characteristic of optical switching necessary for increasing the transmission efficiency can be realized.
[0114]
In addition, when it is determined that a plurality of optical signals scheduled to be input collide due to the provision of the collision determination unit, the optical signal first scheduled to be input to the input / output port among the plurality of optical signals. Since the deflection state of the deflection element is set so as to drop optical signals other than the above, there is an advantage that crosstalk of the optical signal output from the optical switch can be prevented and transmission quality can be improved. .
[0115]
Further, in the deflection element control unit, an optical limiter amplifier that resonates the deflection element and drives the output optical power so as to fluctuate sharply, while removing the optical power fluctuation of the optical signal output from the input / output port of the optical switch. Therefore, the fluctuation of the optical output power caused by the resonance frequency of the deflection element can be surely removed, the level of the output optical signal can be stabilized, and the switching time of the optical path can be increased. There are also advantages.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an optical switching device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing an optical switch according to an embodiment of the present invention.
FIG. 3 is a schematic diagram for explaining a surface position varying action of a tilt mirror constituting an optical switch according to an embodiment of the present invention.
FIG. 4 is a time chart for explaining an operation when detecting an end timing of optical burst signal input by a timer according to an embodiment of the present invention.
FIG. 5 is a diagram for explaining feedback control by an FB control unit in an embodiment of the present invention.
FIG. 6 is a flowchart for explaining an example of optical level control when conventional circuit switching is performed using an optical switch.
FIG. 7 is a flowchart for explaining feedback control by an FB control unit according to an embodiment of the present invention.
FIG. 8 is a flowchart for explaining processing of a collision determination unit in an embodiment of the present invention.
FIG. 9 is a diagram illustrating an example of determining that two bursts collide in a collision determination unit according to an embodiment of the present invention.
FIG. 10 is a schematic diagram for explaining that the surface position of the tilt mirror in the input side mirror array of the optical switch according to the embodiment of the present invention is set to an angle at which the optical burst signal is not reflected on the output side mirror array. It is.
FIGS. 11A to 11C are diagrams for explaining that the resonant frequency component of the optical burst signal is removed by the optical limiter amplifier according to the embodiment of the present invention.
FIG. 12 illustrates that a relatively high gain can be ensured by actively including a resonance frequency fr component in a drive pulse signal according to an embodiment of the present invention compared to a drive pulse signal not including a resonance frequency component. FIG.
FIG. 13 is a block diagram showing provision of an optical limiter amplifier in the subsequent stage of the optical switch in one embodiment of the present invention.
14 (a) to 14 (e), since the optical level of each wavelength component is made uniform by the optical limiter amplifier according to the embodiment of the present invention, the optical amplifier has a uniform level for each wavelength component. It is a figure for demonstrating that it can amplify.
15 (a) to 15 (d), since the optical level of each wavelength component is made uniform by the optical limiter amplifier according to the embodiment of the present invention, the optical amplifier has a uniform level for each wavelength component. It is a figure for demonstrating that it can amplify.
FIG. 16 is a flowchart for explaining the control operation of the optical switch by the optical switching device according to the embodiment of the present invention;
FIG. 17 is a diagram for explaining an optical network based on the premise that routing is performed in units of wavelengths proposed in recent years;
FIG. 18 is a diagram illustrating an optical burst switching network.
[Explanation of symbols]
1 Optical switch
2-input collimator array
2a Input port
3 output collimator array
3a Output port
4 Mirror array
4-1 Input mirror array
4-2 Output mirror array
4a, 4b Tilt mirror
5 Torsion bar
6a, 6b electrode
7 Optical limiter amplifier
8 multiplexer
9 Optical amplifier
10 Routing processor
11 O / E / O converter
12 Reservation Management Department
12A Same route determination unit
12B Collision determination unit
20 Interface section
30 Initial value memory
40 buffer memory
50 Drive writing controller
60 Drive unit
70 Monitor section
80 FB control section
90 timer
100 Optical switching device
900 OBS network
910 Edge node
911 Multiplexer
912 Burst assembly
920 core node
921 Control signal processor
921a O / E / O converter
921b Reservation Management Department
922 Data signal processor
922a Wavelength converter
922b Optical switch matrix

Claims (5)

A plurality of input / output ports for inputting / outputting optical signals of a plurality of channels, respectively, and a deflection element for switching the channels of the optical signals by deflecting the optical signals input to the input / output ports. An optical switch,
Before the optical signal is input to the optical switch, the deflection state of the deflection element is sequentially set based on the switching control information for the optical signal, and when the optical signal is input to the optical switch, A deflection element control unit configured to control the deflection state of the deflection element so that the optical output level of the signal is stabilized at the optical output level at the time when the optical signal output is first detected. An optical switching device. The deflecting element is constituted by a mirror array in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface are arranged,
The deflection element controller
A drive unit that drives each tilt mirror to change the angle of the reflection surface of each tilt mirror;
Based on the switching control information for the optical signal, before the optical signal is input to the optical switch, the reflecting surface angle of the corresponding tilt mirror is sequentially set, and the optical signal is input to the optical switch. Then, in order to control the optical output level of the optical signal to be stabilized at the optical output level at the time when the optical signal output is first detected, a drive control unit that outputs a drive control signal to the drive unit; ,
The optical switching device according to claim 1, comprising: The drive control unit
A switching control information receiving unit for receiving path setting information for transmitting the optical signal as switching control information for the optical signal input from the input / output port before the optical signal is input to the optical switch; ,
Based on the path setting information received by the switching control information receiving unit, a first drive control signal for sequentially setting the reflection surface angle of the corresponding tilt mirror before arrival of the optical signal is supplied to the driving unit. A setting control unit to output to
An optical output monitor for monitoring the output level of light output from the input / output port of the optical switch;
In order to stabilize the level of the optical signal output from the input / output port of the optical switch at the optical output level when the output of the optical signal is confirmed by the optical output monitor, A feedback control unit that outputs a second drive control signal for feedback control of the reflection surface angle;
The optical switching device according to claim 2, comprising: The deflecting element has a plurality of mirror arrays in which a plurality of tilt mirrors capable of changing the angle of the reflecting surface are arranged, and sequentially reflects the optical signals input through the input / output ports by the mirror arrays, It is configured to switch the optical signal channel,
The setting control unit includes a collision determination unit that determines whether or not a collision of optical signals occurs based on the route setting information received by the switching control information receiving unit and the arrival time information and signal length information. With
When it is determined by the collision determination unit that the previous path determined to cause an optical signal collision and the path to be set next are the same, the signal is input after the optical signals that collide. The drive control signal is output to the drive unit so as to switch the reflection surface angle of the tilt mirror in the mirror array on the input side so as to drop the optical signal. The optical switching device described. The deflecting element control unit controls the deflecting element to resonate and the output optical power changes sharply,
2. The optical switching device according to claim 1, further comprising an optical limiter that removes optical power fluctuations of an optical signal output from an input / output port of the optical switch.

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