JPH03149527A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain the highly reliable optical switch by providing optical path selection systems consisting of at least four optical selector switch groups con nected to MXN optical switches (M and N: integer larger than two) and putting the optical selector switch groups in stationary operation while no external energy is injected. CONSTITUTION:A switching operation system D is constituted by arranging 2X2 optical switches D1 and D2 in parallel and the respective 2X2 optical switches are assembled by incorporating eight optical switches. The optical path selection systems E1 and E2 are connected to the input side and output side of the switching operation system D and use four X-branching optical switches 2a-2d. Then the optical selecting switch groups are put in stationary operation while no external energy is injected, so the switching function is never lost unless a 2X2 optical switch is in fault, but if the switch is in fault, optical paths are switched immediately to enable the operation. Consequently, the optical switch which has high reliability on the whole is obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an optical switch, and more specifically, an optical switch that is a combination of waveguide type optical switches using semiconductors, and has a low failure rate and an extremely high failure rate. This invention relates to a reliable optical switch.

(Prior Art) A waveguide type optical switch l having a structure as shown in the perspective view of FIG. 2 is known. This optical switch 1 has a lower cladding layer and a core layer, which are also made of semiconductor, on a semiconductor substrate with a lower electrode formed on the back surface.

The upper cladding layers are sequentially laminated to form a main leading waveguide p1 which is an input port, and two branching optical waveguides p! which are Y-branched from this main optical waveguide p1 at a predetermined branching angle. 1p3 is formed into a ridge shape, and an insulating coating is applied to the entire surface. Then, a part of the insulating coating of each branch optical waveguide pt, ps is removed, and from there, for example, Zn is added into the upper cladding layer.
The structure is such that a pn junction surface is formed by diffusion, and then a predetermined material is deposited, for example, on the pn junction surface, and the electrodes 4 and 5 are attached thereto.

In the case of this optical switch l, when light is input into the main leading waveguide p without injecting current from the electrode 4.5, equally divided output light is emitted from each branch optical waveguide p**Il. .

Then, when a predetermined value of current is injected into one of the electrodes, for example electrode 4, the refractive index of the core layer in this part decreases, so that the light incident from the main optical waveguide p+ is transferred to the branch optical waveguide p! The light is emitted only from the branched optical waveguide p without being emitted from the branched optical waveguide p. In other words, a switching operation occurs.

In this way, the optical switch l having the Y-branch structure functions as a 1-input 2-output optical switch (hereinafter referred to as an 1X2 optical switch).

On the other hand, an optical switch 2 having an X-branching waveguide as shown in the perspective view of FIG. 3 is known.

The waveguide configuration of this optical switch 2 is the same as that of the optical switch shown in FIG.
A slit-shaped window is provided at the center of the intersection where @ and the output port side waveguides ps and pt intersect, and from this, for example, Zn is diffused to form a pn junction corresponding to the shape of the slit-shaped window in the upper cladding layer. It has a structure in which a surface is formed and an electrode 6 is attached thereon.

In the case of this optical switch 2, when no current is injected into the electrode 6, the light incident on the waveguides pa and ps travels straight to the waveguides p, respectively.

Emit from p@ (through state). However, when a predetermined amount of current is injected into the electrode 6, the refractive index of the core layer in that part decreases and a reflective surface is formed, so that the light incident from the waveguide p is emitted from the waveguide p6. without waveguide ps
The light incident from the waveguide p7 is reflected by the reflective surface formed at the intersection and exits only from the waveguide p7.

In this way, this X-branch waveguide optical switch 2 can function as a two-man power two-output optical switch (2x2 optical switch), an lX2 optical switch, or a two-man power one-output optical switch (2x1 optical switch). can be done a -By the way,
By combining the IX2 optical switch l shown in Fig. 2, an M-input N-output optical switch (MXN optical switch, M
, N represents an integer of 2 or more).

This will be explained in the case of a 2×2 optical switch (M=N=2) 3 with reference to FIGS. 4 and 5.

As shown in the conceptual plan view of FIG. 4, waveguides having the above-described configuration are formed in a crossed manner on the semiconductor substrate. In this case, the input ports are A and B, the output ports are A and B, and the waveguides before and after each cross point CI, Ct, Cs, and C4° have second
The lX2 optical switch shown in the figure is incorporated.

The state of its incorporation will be explained based on FIG. 5, which shows the vicinity of the cross point CI.

First, two optical switches l are used at the cross point C1-, a waveguide P1 on the input port A side at the cross point CI and a branch optical waveguide p3 on one side of the optical switch l.
The waveguide P2 on the output port A'' side of the cross point) Cr is connected to the branch optical waveguide P2 of the optical switch I, and the branch optical waveguide p of one optical switch l is The branch optical waveguide p is connected to form a bypass.

At other cross points, the optical switch 1 is incorporated in the same manner as described above, thereby configuring the 1X2 optical switch 3 shown in FIG. 4.

This 1X2 optical switch 3 injects or does not inject current into each electrode on the branched optical waveguide in the optical switch built in each cross point, thereby controlling the throughput of A-A and B-B. Condition, A-B
, B-A can be realized as appropriate.

In this way, the number of waveguides to be crossed is increased,
By incorporating an optical switch l near the corresponding cross point, it is possible to create a MXN optical switch (M and N are integers of 2 or more ) can be assembled.

(Problem to be Solved by the Invention) By the way, it has been recognized that in a waveguide optical switch that performs switching by current injection, the anticonductor deteriorates due to repeated operations, and the switching characteristics deteriorate over time. It will be done. Furthermore, the optical switch may fail for some reason and no longer function as an optical switch.

In optical information systems that are rapidly developing in recent years, there is a strong demand for high reliability, but the reliability of the above-mentioned optical switches alone is insufficient for the optical switches installed in these systems. It has been pointed out that there is a strong demand for the development of even more reliable optical switches.

An object of the present invention is to provide an optical switch with a novel structure that can meet such demands.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a switching system in which at least two MXN optical switches (M, N represent an integer of 2 or more) are arranged in parallel with each other. an optical path selection system including a group of at least four optical selection switches disposed before and after the switching operation system and connected to each of the M×N optical switches; There is provided an optical switch characterized in that the group operates steadily without external energy injection.

The switching operation system in the optical switch of the present invention is as shown in FIGS. 4 and 5.
It is constructed by arranging at least two MXN optical switches assembled in parallel in parallel.

During steady operation, only one of these multiple MxN switches performs a switching operation, and the other MxN switches perform a switching operation.
XN optical switch is not working.

That is, other MXN optical switches are
It is in a standby state as a replacement switch when the N optical switch fails.

M and N optical selection switches are connected to the input side (first stage) and the output side (second stage) of such a switching operation system, respectively, to form an optical path selection system. As this optical selection switch, the optical switch 2 shown in FIG. 3 is used. During steady operation, the device is operated in a through state without external energy injection such as current injection.

Therefore, in the case of the optical selection switches constituting this optical path selection system, during steady operation, no energy is injected into them and they function only as optical waveguides, so the probability that they will fail is extremely small.

If an MXN optical switch that is performing a switching operation fails, external energy such as current injection can be injected into each of the optical selection switches connected before and after the switch to switch them. It is sufficient to change the optical path of the MXN optical switch, switch the switching operation to another MXN optical switch in standby state, and continue operation.

Therefore, this optical switch has high reliability as a whole.

(Embodiments of the Invention) Examples of the optical switch of the present invention will be described below based on the accompanying drawings.

In FIG. 1, the switching operation system is constructed by arranging 2×2 optical switches 01.01 in parallel. Each 2×2 optical switch has a structure as shown in FIG. 4, which is assembled by incorporating eight optical switches 1 shown in FIG. 2.

Optical path selection systems E1. E! are connected to each optical path selection system E1. E! Now, let's look at the X-branch optical switches 2a, 2b, and 2c shown in FIG.

Four pieces of 2d are used.

In the optical path selection system E1, both optical switches 2a and 2b are used as IXZ optical switches. Here, in the optical switch 2a, the waveguide p.

is the optical path L between the input port A of the 2×2 optical switch DI
1, and the waveguide p- forms an optical path between it and the input port A of the 2×2 optical switch D2. Furthermore, in the optical switch 2b, the waveguide p1 is connected to the input port B of the optical switch D, and the optical path L! and waveguide p
・Has optical switch D! is connected to the input boat B of the optical path L.
4 is formed.

On the other hand, in the optical path selection system E, the optical switch 2c.

Both 2d are used as 2Xl optical switches.

Here, the output port A'' of the optical switch DI is connected to the waveguide p1 of the optical switch 2c to form an optical path Ls, and the output port B° of the optical switch D is connected to the waveguide p1 of the optical switch 2d. The output port A'' of the optical switch D is connected to the waveguide pg of the optical switch 2c to form an optical path L7, and the optical switch D!
The output capo)B is connected to the waveguide p1 of the optical switch 2d to form an optical path L1.

In this optical switch, let us now consider the case where the 2×2 optical switch DI is operated in a through state.

At this time, no current is injected from the electrodes formed at the intersections of the optical selection switches 2a, 2b, 2c, and 2d constituting the optical path selection systems E+ and Ex.

First, the light input to the waveguide p4 of the lX2 optical switch 2a continues as it is from the waveguide p1 → optical path L1 → input port A →
The light is output from the 2Xl optical switch 2C through the output port A°→optical path Ls→waveguide p1→waveguide p4.

On the other hand, the light input to the waveguide p4 of the IX2 optical switch 2b continues as it is from the waveguide p1 → optical path → input port B →
Output port B → optical path → waveguide pT → waveguide p4 and output from the 2Xl optical switch 2d.

Therefore, during this operation, the other 2×2 optical switch D!
is not working at all.

Suppose now that the optical switch D1 has malfunctioned. At that time, a predetermined amount of current is injected from the electrodes formed at the intersections of the optical switches 2a, 2b, 2c, and 2d to form light reflecting surfaces there.

The light input to the waveguide p4 of the optical switch 2a is reflected, passes through the waveguide p, and enters the input port A of the optical switch D, and then enters the output port A°.

The light passes through the optical path L1 and enters the waveguide p of the optical switch 2c, is reflected at the intersection, and is output through the waveguide p.

Further, the light input to the waveguide p4 of the optical switch 2b is reflected at the intersection, passes through the waveguide p6, passes through the optical path L4, enters the input port B of the optical switch D, and then enters the output port B of the optical switch D. Light path from °.

, enters the waveguide p6 of the optical switch 2d, is reflected at the intersection, and is output through the waveguide p4.

In this way, when optical switch D fails,
By operating the optical selection switch of the optical path selection system,
Switch the optical path and use optical switch D.

can be operated.

In the optical switch of the present invention, during steady operation when the optical switch DI is operated, each optical switch in the optical path selection system functions only as a waveguide, so the probability that these optical switches will fail is small. , optical switch D
It is significantly smaller than the damaged car with +.

Therefore, this optical switch will not lose its functionality unless both optical switches D+ and Dt forming the switching operation system fail.

That is, it can be used as an optical switch that has extremely high overall reliability.

(Effects of the Invention) As is clear from the above explanation, the optical switch of the present invention has the following features:
At least two MXN optical switches (M.

(N represents an integer of 2 or more) arranged in parallel with each other, and at least four optical selection switches arranged before and after the switching operation system and connected to each of the MxN optical switches. The optical selection switch group has a feature that the optical selection switch group is operated steadily without external energy injection, so that the switching function will not be lost unless the MXN optical switch malfunctions. Furthermore, if an operating MXN optical switch fails, the optical path can be immediately switched and other MXN optical switches arranged in parallel can be operated, providing extremely high reliability as a whole.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a perspective view of a waveguide type Y-branch optical switch, FIG. 3 is a perspective view of a waveguide type X-branch optical switch, and FIG. 4 is a perspective view of a waveguide type Y-branch optical switch. FIG. 5 is a schematic plan view of a 2×2 optical switch incorporating the optical switch shown in the figure, and FIG. 5 is a schematic diagram for explaining the vicinity of the cross point C1 in FIG. 1/Y branch optical switch, 2, 2a, 2b, 2c. 2d...X branch optical switch, 3...2x2 optical switch, 4, 5. 6... Electrode, p+ * px e
pat p4. ps rps, py... waveguide,
A, B...Input boat, Ao. Bo...Output port, Cl* Ct, Cs, C4...
・Cross point, D--Switching operation system, 01
9Dz...2x2 optical switch, E+, Ex...light path selection system, Ll+ Lx, Ls, La, Li, Lm, Lf. Lm...light path.

Claims (1)

[Claims] At least two M-input N-output optical switches (M, N are 2
(representing an integer greater than or equal to)) arranged in parallel with each other, and at least four optical selection switches arranged before and after the switching operation system and connected to each of the M-input and N-output optical switches. 1. An optical switch comprising an optical path selection system consisting of a group of optical selection switches, the optical selection switch group being operated in a steady state without external energy injection.