CN217445362U - Optical module and laser assembly - Google Patents

Abstract

In an optical module provided by the present application, a laser module includes: the high-frequency signal line is arranged on one side of the first reference ground, and the matching circuit is arranged on the other side of the first reference ground and is electrically connected with the first reference ground; the laser chip is arranged on the first reference ground in a mounting manner, and the input end of the laser chip is connected with the high-frequency signal wire and the matching circuit in a routing manner; the matching circuit comprises a first bonding pad, a second bonding pad, a third bonding pad, a first resistor, an inductor and a capacitor; the input end of the laser chip is connected with a first bonding pad in a routing way, one end of a first resistor is electrically connected with the first bonding pad, and the other end of the first resistor is electrically connected with a second bonding pad; one end of the inductor is electrically connected with the second bonding pad, and the other end of the inductor is electrically connected with the third bonding pad; one end of the capacitor is electrically connected with the third bonding pad, and the other end of the capacitor is electrically connected with the first reference ground; the inductor is used for compensating the low impedance characteristic of the capacitor and is used for improving the bandwidth of the laser chip through inductive compensation. For reducing impedance mismatch of the EAM and the transmission line.

Description

Optical module and laser assembly

Technical Field

The application relates to the technical field of optical fiber communication, in particular to an optical module and a laser assembly.

Background

With the development of new services and application modes such as cloud computing, mobile internet, video and the like, the development and progress of the optical communication technology become increasingly important. In the optical communication technology, an optical module is a tool for realizing the interconversion of optical signals and is one of key devices in optical communication equipment, and the transmission rate of the optical module is continuously increased along with the development requirement of the optical communication technology.

The laser module is one of the core components in the optical module, and the requirements for the high-frequency performance of the laser module are continuously increased along with the development of the optical communication technology. The laser assembly comprises a laser, and in order to facilitate assembly and use of the laser, the laser assembly further comprises a substrate, and the laser is arranged on the substrate in a mounting mode. An Electro-Absorption modulated laser (EML) is a laser commonly used in laser components, and the EML monolithically integrates an Electro-Absorption Modulator (EAM) and a DFB (distributed Feed back) laser, thereby not only solving the phenomena of spectral broadening and frequency response relaxation oscillation caused by chirp of the DFB laser under high-frequency modulation, but also reducing the cost and the package size when obtaining high coupling efficiency and high output power of modulated light between the Modulator and the laser, and thus having wide application prospects.

However, when the EML is used, a reverse bias voltage needs to be applied to the EAM, which causes the EAM to be in a large internal resistance state, which easily causes impedance mismatch between the EAM and the transmission line and increases reflection of the channel, so that the performance of the EAM cannot reach a better level.

SUMMERY OF THE UTILITY MODEL

The embodiment of the application provides an optical module and a laser assembly, which are used for reducing impedance mismatch between an EAM and a transmission line so as to reduce channel reflection.

In a first aspect, the present application provides an optical module, including:

a circuit board;

the optical transceiving component is electrically connected with the circuit board and comprises an optical transmitting device used for receiving optical signals;

wherein the light emitting device comprises;

a substrate on a top surface of which a first reference ground, a high frequency signal line and a matching circuit are disposed, the high frequency signal line being disposed at one side of the first reference ground, the matching circuit being disposed at the other side of the first reference ground and the matching circuit being electrically connected to the first reference ground;

the laser chip is arranged on the first reference ground in a mounting mode, and the input end of the laser chip is connected with the high-frequency signal wire in a routing mode and the matching circuit in a routing mode;

the matching circuit comprises a first bonding pad, a second bonding pad, a third bonding pad, a first resistor, an inductor and a capacitor; the input end of the laser chip is connected with the first bonding pad in a routing way, one end of the first resistor is electrically connected with the first bonding pad, and the other end of the first resistor is electrically connected with the second bonding pad; one end of the inductor is electrically connected with the second bonding pad, and the other end of the inductor is electrically connected with the third bonding pad; one end of the capacitor is electrically connected with the third bonding pad, and the other end of the capacitor is electrically connected with the first reference ground; the inductor is used for compensating the low impedance characteristic of the capacitor and improving the bandwidth of the laser chip through inductance compensation.

In a second aspect, the present application provides a laser assembly comprising:

a substrate on a top surface of which a first reference ground, a high frequency signal line and a matching circuit are disposed, the high frequency signal line being disposed at one side of the first reference ground, the matching circuit being disposed at the other side of the first reference ground and the matching circuit being electrically connected to the first reference ground;

the laser chip is arranged on the first reference ground in a mounting mode, and the input end of the laser chip is connected with the high-frequency signal wire in a routing mode and the matching circuit in a routing mode;

the matching circuit comprises a first bonding pad, a second bonding pad, a third bonding pad, a first resistor, an inductor and a capacitor; the input end of the laser chip is connected with the first bonding pad in a routing way, one end of the first resistor is electrically connected with the first bonding pad, and the other end of the first resistor is electrically connected with the second bonding pad; one end of the inductor is electrically connected with the second bonding pad, and the other end of the inductor is electrically connected with the third bonding pad; one end of the capacitor is electrically connected with the third bonding pad, and the other end of the capacitor is electrically connected with the first reference ground; the inductor is used for compensating the low impedance characteristic of the capacitor and improving the bandwidth of the laser chip through inductance compensation.

In the optical module and the laser assembly, a first reference ground, a high-frequency signal line and a matching circuit are arranged on the top surface of a substrate, a laser chip is arranged on the first reference ground in a pasting mode, and the input end of the laser chip is connected with the high-frequency signal line and the matching circuit in a routing mode respectively to enable the matching circuit to be connected with the laser chip in parallel; the matching circuit comprises a first resistor, an inductor and a capacitor, the first resistor, the inductor and the capacitor are sequentially connected in series, and the tail end of the capacitor is connected with a first reference ground to realize the grounding of the capacitor. In the matching circuit provided by the application, the inductor is arranged between the first resistor and the capacitor, so that the bandwidth of the laser chip can be improved by utilizing an inductance compensation technology under the condition that signal reflection is not increased; meanwhile, the low impedance characteristic of the inductance compensation capacitor improves the equivalent terminal impedance of the laser chip and the matching network, so that the impedance of the matching network can be close to the characteristic impedance of transmission lines such as a high-frequency signal line, the channel reflection is reduced, and the allowance of an eye pattern template of the laser chip is improved.

Drawings

In order to more clearly illustrate the technical solutions in the present disclosure, the drawings needed to be used in some embodiments of the present disclosure will be briefly described below, and it is apparent that the drawings in the following description are only drawings of some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art according to the drawings. Furthermore, the drawings in the following description may be regarded as schematic diagrams, and do not limit the actual size of products, the actual flow of methods, the actual timing of signals, and the like, involved in the embodiments of the present disclosure.

Fig. 1 is a connection diagram of an optical communication system;

FIG. 2 is a block diagram of an optical network terminal;

fig. 3 is a schematic structural diagram of a light module according to some embodiments;

FIG. 4 is an exploded view illustration of a light module provided in accordance with some embodiments;

FIG. 5 is a block diagram of an external form of a light emitting device according to some embodiments;

FIG. 6 is an exploded schematic view of a light emitting device provided in accordance with some embodiments;

FIG. 7 is a schematic diagram of a laser assembly according to some embodiments;

FIG. 8 is a schematic diagram of a laser chip according to some embodiments;

FIG. 9 is a schematic structural diagram of another laser assembly provided in accordance with some embodiments;

FIG. 10 is a schematic diagram of another laser chip provided in accordance with some embodiments;

FIG. 11 is a schematic diagram of yet another laser assembly provided in accordance with some embodiments;

FIG. 12 is a first schematic diagram of a further laser assembly according to some embodiments;

fig. 13 is a second schematic structural view of a substrate according to some embodiments;

fig. 14 is a schematic structural diagram of a substrate according to some embodiments;

fig. 15 is an eye diagram provided in accordance with some embodiments;

fig. 16 is another eye diagram provided in accordance with some embodiments;

fig. 17 is yet another eye diagram provided in accordance with some embodiments.

Detailed Description

Technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided by the present disclosure belong to the protection scope of the present disclosure.

In an optical communication system, an optical signal is used to carry information to be transmitted, and the optical signal carrying the information is transmitted to information processing equipment such as a computer through information transmission equipment such as an optical fiber or an optical waveguide, so as to complete information transmission. Since light has a passive transmission characteristic when transmitted through an optical fiber or an optical waveguide, low-cost, low-loss information transmission can be realized. Further, since a signal transmitted by an information transmission device such as an optical fiber or an optical waveguide is an optical signal and a signal that can be recognized and processed by an information processing device such as a computer is an electrical signal, it is necessary to perform interconversion between the electrical signal and the optical signal in order to establish an information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer.

The optical module realizes the function of interconversion between the optical signal and the electrical signal in the technical field of optical communication. The optical module comprises an optical port and an electrical port, the optical module realizes optical communication with information transmission equipment such as optical fibers or optical waveguides and the like through the optical port, realizes electrical connection with an optical network terminal (such as an optical modem) through the electrical port, and the electrical connection is mainly used for power supply, I2C signal transmission, data information transmission, grounding and the like; the optical network terminal transmits the electric signal to the computer and other information processing equipment through a network cable or a wireless fidelity (Wi-Fi).

Fig. 1 is a connection diagram of an optical communication system. As shown in fig. 1, the optical communication system includes a remote server 1000, a local information processing device 2000, an optical network terminal 100, an optical module 200, an optical fiber 101, and a network cable 103.

One end of the optical fiber 101 is connected to the remote server 1000, and the other end is connected to the optical network terminal 100 through the optical module 200. The optical fiber itself can support long-distance signal transmission, for example, signal transmission of several kilometers (6 kilometers to 8 kilometers), on the basis of which if a repeater is used, infinite distance transmission can be theoretically achieved. Therefore, in a typical optical communication system, the distance between the remote server 1000 and the optical network terminal 100 may be several kilometers, tens of kilometers, or hundreds of kilometers.

One end of the network cable 103 is connected to the local information processing device 2000, and the other end is connected to the optical network terminal 100. The local information processing apparatus 2000 may be any one or several of the following apparatuses: router, switch, computer, cell-phone, panel computer, TV set etc..

The physical distance between the remote server 1000 and the optical network terminal 100 is greater than the physical distance between the local information processing apparatus 2000 and the optical network terminal 100. The connection between the local information processing apparatus 2000 and the remote server 1000 is made by the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical module 200 and the optical network terminal 100.

The optical module 200 includes an optical port configured to access the optical fiber 101, and an electrical port, such that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101; the electrical port is configured to be accessed into the optical network terminal 100, so that the optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100. The optical module 200 converts an optical signal and an electrical signal to each other, so that an information connection is established between the optical fiber 101 and the optical network terminal 100. For example, an optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input to the optical network terminal 100, and an electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input to the optical fiber 101. Since the optical module 200 is a tool for implementing the interconversion between the optical signal and the electrical signal, and has no function of processing data, information is not changed in the above-mentioned photoelectric conversion process.

The optical network terminal 100 includes a housing (housing) having a substantially rectangular parallelepiped shape, and an optical module interface 102 and a network cable interface 104 provided on the housing. The optical module interface 102 is configured to access the optical module 200, so that the ont 100 establishes a bidirectional electrical signal connection with the optical module 200; the network cable interface 104 is configured to access the network cable 103, such that the optical network terminal 100 establishes a bidirectional electrical signal connection with the network cable 103. The optical module 200 is connected to the network cable 103 via the optical network terminal 100. For example, the optical network terminal 100 transmits the electrical signal from the optical module 200 to the network cable 103, and transmits the electrical signal from the network cable 103 to the optical module 200, so that the optical network terminal 100 can monitor the operation of the optical module 200 as an upper computer of the optical module 200. The upper computer of the Optical module 200 may include an Optical Line Terminal (OLT) and the like in addition to the Optical network Terminal 100.

The remote server 1000 establishes a bidirectional signal transmission channel with the local information processing device 2000 through the optical fiber 101, the optical module 200, the optical network terminal 100, and the network cable 103.

Fig. 2 is a configuration diagram of the optical network terminal, and fig. 2 only shows a configuration of the optical module 200 of the optical network terminal 100 in order to clearly show a connection relationship between the optical module 200 and the optical network terminal 100. As shown in fig. 2, the optical network terminal 100 further includes a circuit board 105 disposed within the housing, a cage 106 disposed on a surface of the circuit board 105, a heat sink 107 disposed on the cage 106, and an electrical connector disposed inside the cage 106. The electrical connector is configured to access an electrical port of the optical module 200; the heat sink 107 has a projection such as a fin that increases a heat radiation area.

The optical module 200 is inserted into a cage 106 of the optical network terminal 100, the cage 106 holds the optical module 200, and heat generated by the optical module 200 is conducted to the cage 106 and then diffused by a heat sink 107. After the optical module 200 is inserted into the cage 106, the electrical port of the optical module 200 is connected to the electrical connector inside the cage 106, so that the optical module 200 is connected to the optical network terminal 100 by a bidirectional electrical signal. Further, the optical port of the optical module 200 is connected to the optical fiber 101, and the optical module 200 establishes bidirectional optical signal connection with the optical fiber 101.

Fig. 3 is a block diagram of an optical module according to some embodiments, and fig. 4 is an exploded schematic diagram of an optical module according to some embodiments. As shown in fig. 3 and 4, the optical module 200 includes a housing (shell), a circuit board 206 disposed in the housing, and an optical transceiver module 207.

The shell comprises an upper shell 201 and a lower shell 202, wherein the upper shell 201 is covered on the lower shell 202 to form the shell with two openings; the outer contour of the housing generally appears square.

In some embodiments of the present disclosure, the lower housing 202 includes a bottom plate 2021 and two lower side plates 2022 located at both sides of the bottom plate 2021 and disposed perpendicular to the bottom plate 2021; the upper case 201 includes a cover 2011, and the cover 2011 covers the two lower side plates 2022 of the lower case 202 to form the above case.

In some embodiments, the lower housing 202 includes a bottom plate 2021 and two lower side plates 2022 located at both sides of the bottom plate 2021 and disposed perpendicular to the bottom plate 2021; the upper housing 201 includes a cover 2011 and two upper side plates located on two sides of the cover 2011 and perpendicular to the cover 2011, and the two upper side plates are combined with the two lower side plates 2022 to cover the upper housing 201 on the lower housing 202.

The direction of the connecting line of the two openings 204 and 205 may be the same as the length direction of the optical module 200, or may not be the same as the length direction of the optical module 200. For example, the opening 204 is located at an end portion (right end in fig. 3) of the optical module 200, and the opening 205 is also located at an end portion (left end in fig. 3) of the optical module 200. Alternatively, the opening 204 is located at an end of the optical module 200, and the opening 205 is located at a side of the optical module 200. The opening 204 is an electrical port, and a gold finger of the circuit board 206 extends out of the electrical port 204 and is inserted into an upper computer (for example, the optical network terminal 100); the opening 205 is an optical port configured to access the external optical fiber 101, so that the external optical fiber 101 is connected to the optical transceiver module 207 inside the optical module 200.

The upper shell 201 and the lower shell 202 are combined to assemble the circuit board 206, the optical transceiver module 207 and other devices in the shell, and the upper shell 201 and the lower shell 202 form encapsulation protection for the devices. In addition, when the devices such as the circuit board 206 and the optical transceiver module 207 are assembled, the positioning components, the heat dissipation components and the electromagnetic shielding components of the devices are convenient to deploy, and the automatic production is facilitated.

In some embodiments, the upper housing 201 and the lower housing 202 are generally made of metal materials, which is beneficial to achieve electromagnetic shielding and heat dissipation.

In some embodiments, the optical module 200 further includes an unlocking part 203 located outside the housing thereof, and the unlocking part 203 is configured to realize a fixed connection between the optical module 200 and the upper computer or release the fixed connection between the optical module 200 and the upper computer.

For example, the unlocking member 203 is located on the outer walls of the two lower side plates 2022 of the lower housing 202, and has a snap-fit member that matches with a cage of the upper computer (for example, the cage 106 of the optical network terminal 100). When the optical module 200 is inserted into the cage of the upper computer, the optical module 200 is fixed in the cage of the upper computer by the engaging member of the unlocking member 203; when the unlocking member 203 is pulled, the engaging member of the unlocking member 203 moves along with the unlocking member, and the connection relationship between the engaging member and the upper computer is changed, so that the engagement relationship between the optical module 200 and the upper computer is released, and the optical module 200 can be drawn out from the cage of the upper computer.

The circuit board 206 includes circuit traces, electronic components, and chips, and the electronic components and the chips are connected together by the circuit traces according to a circuit design to implement functions of power supply, electrical signal transmission, grounding, and the like. Examples of the electronic components include capacitors, resistors, transistors, and Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs). The chip includes, for example, a Micro Controller Unit (MCU), a laser driver chip, a limiting amplifier (limiting amplifier), a Clock and Data Recovery (CDR) chip, a power management chip, and a Digital Signal Processing (DSP) chip.

The circuit board 206 is generally a rigid circuit board, which can also perform a bearing function due to its relatively rigid material, for example, the rigid circuit board can stably bear the electronic components and chips; when the optical transceiver component is positioned on the circuit board, the rigid circuit board can also provide smooth bearing; the rigid circuit board can also be inserted into an electric connector in the cage of the upper computer.

The circuit board 206 further includes a gold finger formed on an end surface thereof, the gold finger being composed of a plurality of pins independent of each other. The circuit board 206 is inserted into the cage 106 and electrically connected to the electrical connectors in the cage 106 by gold fingers. The gold fingers may be disposed on only one side of the circuit board 206 (e.g., the upper surface shown in fig. 4), or may be disposed on both upper and lower sides of the circuit board 206, so as to adapt to the situation where the requirement of the number of pins is large. The golden finger is configured to establish an electrical connection with the upper computer to achieve power supply, grounding, I2C signal transmission, data signal transmission and the like.

Of course, a flexible circuit board is also used in some optical modules. Flexible circuit boards are commonly used in conjunction with rigid circuit boards to supplement the rigid circuit boards. For example, a flexible circuit board may be used to connect the rigid circuit board and the optical transceiver module.

The optical transceiver component 207 includes an optical transmitter 300 and an optical receiver, the optical transmitter 300 is configured to transmit optical signals, and the optical receiver is configured to receive optical signals. Illustratively, the light emitting device 300 and the light receiving device are bonded together to form an integrated optical transceiver module.

Fig. 5 provides a block diagram of an external form of a light emitting device according to some embodiments. As shown in fig. 5, the light emitting device 300 provided in this embodiment includes a stem 310, a cap 320, and other devices disposed in the cap 320 and the stem 310, the cap 320 is covered at one end of the stem 310, the stem 310 includes a plurality of pins, and the pins are used to electrically connect the flexible circuit board to other electrical devices in the light emitting device 300, and further electrically connect the light emitting device 300 to the circuit board 206.

Fig. 6 is an exploded schematic view of a light emitting device provided in accordance with some embodiments. As shown in fig. 6, in some embodiments, the light emitting device 300 includes a laser assembly 400, the laser assembly 400 being configured to generate an optical signal and the generated optical signal being transmitted through the cap 320. Of course, in some embodiments of the present application, the usage form of the laser assembly 400 is not limited to the structure shown in fig. 6, and the laser assembly 400 may also be directly mounted on the circuit board 206.

Fig. 7 is a schematic structural diagram of a laser assembly according to some embodiments. As shown in fig. 7, the laser module 400 includes a laser chip 410 and a substrate 420, wherein a circuit is laid on the upper surface of the substrate 420, and the laser chip 410 is connected to the corresponding circuit on the substrate 420 by wire bonding. The laser chip 410 may be an EML; the substrate 420 and the bonding wires between the laser chip 410 and the substrate 420 are package structures, so that the EML and the substrate 420 are packaged to form an EML laser assembly. In the embodiment of the present application, the structure of the laser module 400 is not limited to the structure shown in fig. 7, and may be a laser module with other structural forms; the substrate 420 may be a ceramic substrate, but is not limited thereto.

Since the EAM in the laser chip 410 needs to be applied with a reverse bias voltage, the EAM in the laser chip 410 is in a large internal resistance state, and in order to reduce the impedance mismatch between the EAM and the transmission line and improve reflection, in some embodiments, the laser module 400 further includes a matching circuit 430, and the matching circuit 430 is connected in parallel with the laser chip 410. The matching circuit 430 is disposed on the substrate 420; the matching circuit 430 generally includes resistors for impedance matching with the transmission line, and capacitors for reducing power consumption of devices in the matching circuit. When the impedance of the matching circuit 430 is mismatched with the impedance of the transmission line, the performance of the laser chip 410 cannot reach a better level, and particularly, the performance of the EAM in the laser chip 410 is slightly poor, the eye pattern of the laser chip 410 has more noise points and larger jitter, which results in insufficient eye pattern template margin.

In order to reduce the impedance mismatch between the laser chip 410 and the transmission line, the embodiment of the present application further provides a matching circuit 430, and the matching circuit 430 further includes an inductor, and the inductor is connected in series between the resistor and the capacitor. Fig. 8 is a schematic diagram of a laser chip according to some embodiments, and fig. 8 shows a schematic circuit diagram of a matching circuit 430. As shown in fig. 8, a matching circuit 430 is connected in parallel with the laser chip 410, the matching circuit 430 including a first resistor 434, an inductor 435, and a capacitor 436; one end of the first resistor 434 is electrically connected to the input end of the laser chip 410, the other end is connected to one end of the inductor 435, the other end of the inductor 435 is connected to one end of the capacitor 436, and the other end of the capacitor 436 is grounded.

To facilitate the arrangement and use of the matching circuit 430 provided in the embodiments of the present application, another laser assembly 400 is also provided in the embodiments of the present application. Fig. 9 is a schematic structural diagram of another laser assembly provided in accordance with some embodiments. As shown in fig. 9, the laser module 400 provided in the embodiment of the present application also includes a laser chip 410 and a substrate 420; a first reference ground 421, a high-frequency signal line 422, and a matching circuit 430 are provided on the substrate 420; the laser chip 410 is mounted on the substrate 420, and the input end of the laser chip 410 is connected with the high-frequency signal line 422 by wire bonding. In some embodiments, the high frequency signal line 422 is disposed on one side of the first reference ground 421, and the matching circuit 430 is disposed on the other side of the first reference ground 421, so as to control the bonding length of the input end of the laser chip 410 to the high frequency signal line 422 and the matching circuit 430 and to properly arrange the space on the top surface of the substrate 420.

The matching circuit 430 includes a first pad 431, a second pad 432, a third pad 433, a first resistor 434, an inductor 435, and a capacitor 436; a first pad 431, a second pad 432, and a third pad 433 are disposed on a surface of the top of the substrate 420; one end of the first resistor 434 is electrically connected to the first pad 431, and the other end is electrically connected to the second pad 432; one end of the inductor 435 is electrically connected to the second pad 432, and the other end is electrically connected to the third pad 433; one end of the capacitor 436 is electrically connected to the third pad 433, and the other end is electrically connected to the first reference ground 421; the input end of the laser chip 410 is wire-bonded to the first bonding pad 431. The laser chip 410 is in turn connected in parallel with a matching circuit 430 comprising a first resistor 434, an inductor 435 and a capacitor 436. In the present embodiment, the specific values of the first resistor 434, the inductor 435, and the capacitor 436 may be determined by high frequency simulation in conjunction with the laser chip 410. The first resistor 434 may be a thin film resistor.

The inductor presents high impedance at high frequency, which increases the reflection of the channel, and is generally considered harmful to high frequency signal transmission, and in the embodiment of the present invention, the inductor 435 is connected in series between the first resistor 434 and the capacitor 436, so that the inductor 435 is connected in parallel with the laser chip 410, and a resonance is created at the nyquist frequency S21, which can increase the bandwidth of the laser chip 4101dB, thereby increasing the openness of the eye pattern and improving the quality of the eye pattern. Since most of the signal energy is distributed below the nyquist frequency from the point of view of the signal spectral energy distribution, the attenuation from DC to the nyquist frequency S21 should be less than 1dB in order to reduce the attenuation of the signal. However, for an ideal transmission line, the attenuation of the signal must increase with increasing frequency, and especially in the case that the laser chip itself has parasitic capacitance and junction capacitance, the attenuation of the signal will be further increased, which results in insufficient bandwidth of 1dB, and as a result, the rising edge and the falling edge of the eye diagram from the laser chip are longer, and the eye diagram is closed. In order to improve the 1dB bandwidth of the channel, the matching circuit 430 provided in the embodiment of the present application can improve the 1dB bandwidth of the channel by using the inductance compensation technique without increasing the reflection.

Further, another important factor affecting the eye diagram of the laser chip is reflection, the root of which is the impedance mismatch of the termination of the EAM and the channel transmission line design in the laser chip 410. Because the EAM has parasitic capacitance and junction capacitance, the capacitance has low impedance characteristic under high frequency, and the mismatching of terminal impedance and transmission line impedance is shown, so that larger reflection exists, a plurality of eye pattern noise points from the chip are caused, and the eye pattern template allowance is insufficient. In the matching circuit 430 provided by the embodiment of the application, the introduced inductor 435 can be used for compensating the low impedance characteristic of the capacitor, so that the equivalent terminal impedance of the EAM chip and the matching network is improved to be as close as possible to the characteristic impedance of the transmission line, thereby reducing reflection and improving the chip eye pattern template margin.

Fig. 10 is a schematic diagram of another laser chip according to some embodiments, and fig. 10 shows a schematic circuit diagram of a matching circuit 430. As shown in fig. 10, in some embodiments, the matching circuit 430 further includes a second resistor 437, one end of the second resistor 437 is electrically connected to the input terminal of the laser chip 410, the other end is connected to one end of the capacitor 436, and the second resistor 437 is connected in parallel with the first resistor 434 and the inductor 435 and in series with the second resistor 437 and the capacitor 436.

In order to facilitate the arrangement of the matching circuit 430 shown in fig. 10 and ensure the use performance of the matching circuit 430, the embodiment of the present application further provides a laser assembly 400. Fig. 11 is a schematic structural diagram of another laser assembly according to some embodiments. As shown in fig. 11, the laser module 400 shown in fig. 11 has a second resistor 437 added to the laser module 400 shown in fig. 9, which facilitates further improving the performance of the matching circuit 430. Illustratively, the surface of the top of the substrate 420 is further provided with a fourth pad 438, and one end of the second resistor 437 is electrically connected to the first pad 431, and the other end is electrically connected to the fourth pad 438.

Fig. 12 is a first schematic structural diagram of a substrate according to some embodiments. As shown in fig. 12, the top surface of the substrate 420 is provided with a first reference ground 421, a high-frequency signal line 422, a first pad 431, a second pad 432, a third pad 433, and a fourth pad 438; the first reference ground 421 is disposed along the width direction of the substrate 420, the high frequency signal line 422 is disposed at one side of the first reference ground 421, and the first pad 431, the second pad 432, the third pad 433, and the fourth pad 438 are disposed at the other side of the first reference ground 421.

The laser chip 410 is typically disposed on the top edge of the substrate 420. Illustratively, the laser chip 410 is disposed on the substrate 420 near the first side 420-1, and further the input end of the laser chip 410 is near the first side 420-1, and in order to control the bonding length between the input end of the laser chip 410 and the high-frequency signal line 422, the high-frequency signal line 422 is near the first side 420-1 and near the input end of the laser chip 410. Further, to control the bonding length between the input end of the laser chip 410 and the first bonding pad 431, the first bonding pad 431 is close to the first side 420-1 and close to the input end of the laser chip 410.

In some implementations, one end of the high-frequency signal line 422 is close to the first reference ground 421, and the other end extends in a direction in which a side connected to the first side 420-1 is located. In order to ensure the use of the high frequency signal line 422, a branch is further disposed on the substrate 420, the branch is disposed at a side of the high frequency signal line 422, and the branch is connected to the first reference ground 421, so that the branch and the high frequency signal line 422 form a transmission line structure. Illustratively, one side of the high-frequency signal line 422 is provided with a first branch 423, the other side is provided with a second branch 424, one end of the first branch 423 and one end of the second branch 424 are respectively electrically connected with the first reference ground 421, one end of the first branch 423 and the second branch 424 extend along the extending direction of the high-frequency signal line 422, and the first branch 423, the high-frequency signal line 422 and the second branch 424 form a transmission line structure in the form of a GSG.

In some embodiments, the high frequency signal line 422 is obliquely disposed on the substrate 420 in order to allow sufficient space for the disposition of the second branch 424 since the high frequency signal line 422 is close to the first side 420-1. In some embodiments, a fifth predetermined gap is provided between the first branch 423 and the high frequency signal line 422, a sixth predetermined gap is provided between the second branch 424 and the high frequency signal line 422, and the fifth predetermined gap and the sixth predetermined gap are equal. The width values of the fifth and sixth preset gaps may be obtained by combining the size of the substrate 420 and by simulation calculation.

In some embodiments, the second pad 432 and the fourth pad 438 are disposed side by side at the other side of the first reference ground 421, and a first preset gap is disposed between the second pad 432 and the fourth pad 438, and the first preset gap is used to prevent the second pad 432 and the fourth pad 438 from being shorted when the second pad 432 is connected to the first resistor 434 or when the fourth pad 438 is connected to the second resistor 437; the fourth pad 438 is closer to the first reference ground 421 than the second pad 432, and a second predetermined gap is disposed between the fourth pad 438 and the first reference ground 421, and the second predetermined gap is used to prevent the fourth pad 438 from being short-circuited with the first reference ground 421 when the fourth pad 438 is connected to the second resistor 437.

In some embodiments, the third bonding pad 433 includes a first connection region 4331 and a second connection region 4332, the first connection region 4331 is used for electrically connecting the capacitor 436, and the second connection region 4332 is used for wire bonding the fourth bonding pad 438; a third predetermined gap is formed between the first connection region 4331 and the first reference ground 421, and the third predetermined gap is used to prevent the capacitor 436 from being electrically connected to the third pad 433 or the first reference ground 421 to cause the third pad 433 to be short-circuited with the first reference ground 421; a fourth predetermined gap is disposed between the second connection region 4332 and the first reference ground 421, and the fourth predetermined gap is used to prevent the second connection region 4332 from being short-circuited with the first reference ground 421. In some embodiments, the third predetermined gap has a width greater than the fourth predetermined gap, taking into account the actual need to electrically connect the capacitor 436.

In some embodiments, the fourth pad 438 is disposed on the substrate 420, so as to facilitate compatibility of the matching circuit 430, that is, selecting the same substrate 420 may further control whether to wire the fourth pad 438 and the third pad 433, whether to use the second resistor 437 in the matching circuit 430 circuit, and so on.

In some embodiments, to increase the ground area on the substrate 420, the bottom on the substrate 420 is also typically set to a reference ground; the first reference ground 421 on the top of the substrate 420 is electrically connected to the reference ground on the bottom of the substrate 420. Typically, the first reference ground 421 on the top of the substrate 420 is electrically connected to the reference ground on the bottom of the substrate 420 through a via.

Fig. 13 is a second schematic structural diagram of a substrate according to some embodiments. As shown in fig. 13, the surface of the bottom of the substrate 420 is provided with a second reference ground 425, and the second reference ground 425 is electrically connected to the first reference ground 421. In some embodiments, the second reference ground 425 may be distributed over the surface of the bottom of the substrate 420 or partially distributed over the surface of the bottom of the substrate 420.

In some embodiments, a metal layer 526 is disposed on the first side 420-1, the metal layer 526 being used to electrically connect the first reference ground 421 and the second reference ground 425. The first reference ground 421 and the second reference ground 425 are electrically connected by providing a metal layer on the first side 420-1, which is convenient in process. Illustratively, the metal layer 526 covers the entire plane of the first side 420-1, facilitating the provision of the metal layer 526 on the first side 420-1. The metal layer 526 is typically formed by plating the first side 420-1 with gold.

Fig. 14 is a third schematic structural diagram of a substrate according to some embodiments. As shown in fig. 14, to facilitate the electrical connection of the first reference ground 421 and the second reference ground 425 through the metal layer 526, the first reference ground 421 extends to the interface of the top surface of the substrate 420 and the first side 420-1. Illustratively, the first reference ground 421 on the top surface of the substrate 420 has a larger width near the first side 420-1, so that the first reference ground 421 has sufficient contact space for electrically connecting with the metal layer 526.

Fig. 15 is an eye diagram provided in accordance with some embodiments, and fig. 15 shows an eye diagram of a laser chip 410 of the laser assembly 400 in which the matching circuit 430 employs a combination of resistors and capacitors. As shown in fig. 15, the jitter of the eye pattern is large and the eye line in the eye pattern is thick. Fig. 16 is another eye diagram provided in accordance with some embodiments, and fig. 16 illustrates an eye diagram of the laser assembly 400 of fig. 9 in relation to a laser chip 410. As shown in fig. 16, the jitter of the eye pattern is reduced and improved significantly, and the rising and falling processes of the eye pattern are also slightly collapsed, slightly affecting the edge of the eye pattern. Fig. 17 is yet another eye diagram provided in accordance with some embodiments, and fig. 17 illustrates an eye diagram of the laser assembly 400 of fig. 11 in relation to a laser chip 410. As shown in fig. 17, the jitter of the eye pattern is significantly improved and the eye pattern shape is very good. Therefore, in the laser module 400 provided in the embodiment of the present application, by serially connecting the inductor 435 between the first resistor 434 and the capacitor 436 in the matching circuit board 430, the inductor 435 can increase the bandwidth of the laser core 410 by using the inductance compensation technique without increasing the signal reflection; meanwhile, the low impedance characteristic of the inductor 435 and the compensation capacitor 436 improves the equivalent terminal impedance of the laser chip 410 and the matching network, so that the impedance of the matching network can be close to the characteristic impedance of transmission lines such as high-frequency signal lines, and the like, thereby reducing channel reflection and improving the margin of the eye pattern template of the laser chip 410.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present application.

Claims (10)

1. A light module, comprising:

a circuit board;

the optical transceiving component is electrically connected with the circuit board and comprises an optical transmitting device used for receiving optical signals;

wherein the light emitting device includes a laser assembly, the laser assembly including:

a substrate on a top surface of which a first reference ground, a high frequency signal line and a matching circuit are disposed, the high frequency signal line being disposed at one side of the first reference ground, the matching circuit being disposed at the other side of the first reference ground and the matching circuit being electrically connected to the first reference ground;

the laser chip is arranged on the first reference ground in a mounting mode, and the input end of the laser chip is connected with the high-frequency signal wire in a routing mode and the matching circuit in a routing mode;

the matching circuit comprises a first bonding pad, a second bonding pad, a third bonding pad, a first resistor, an inductor and a capacitor; the input end of the laser chip is connected with the first bonding pad in a routing way, one end of the first resistor is electrically connected with the first bonding pad, and the other end of the first resistor is electrically connected with the second bonding pad; one end of the inductor is electrically connected with the second bonding pad, and the other end of the inductor is electrically connected with the third bonding pad; one end of the capacitor is electrically connected with the third bonding pad, and the other end of the capacitor is electrically connected with the first reference ground; the inductor is used for compensating the low impedance characteristic of the capacitor and improving the bandwidth of the laser chip through inductance compensation.

2. The optical module of claim 1, wherein the matching circuit further comprises a fourth pad and a second resistor, one end of the second resistor is electrically connected to the first pad, the other end of the second resistor is electrically connected to the fourth pad, and the fourth pad is wire-bonded to the third pad.

3. The optical module of claim 2, wherein the fourth pad and the second pad are disposed side by side on the other side of the first reference ground, a first predetermined gap is disposed between the fourth pad and the second pad, the fourth pad is closer to the first reference ground than the second pad, and a second predetermined gap is disposed between the fourth pad and the first reference ground.

4. The optical module of claim 3, wherein the third bonding pad comprises a first connection area and a second connection area, the first connection area is electrically connected with the capacitor, and the second connection area is wire-bonded with the fourth bonding pad; and a third preset gap is arranged between the first connecting area and the first reference ground, a fourth preset gap is arranged between the second connecting area and the first reference ground, and the width of the third preset gap is greater than that of the fourth preset gap.

5. The optical module of claim 1, wherein a second reference ground is disposed on a bottom surface of the substrate, the second reference ground being electrically connected to the first reference ground.

6. The optical module of claim 5, wherein the substrate comprises a first side near the laser chip input, the first side having a metal layer disposed thereon, the metal layer electrically connecting the first and second reference grounds.

7. The optical module according to claim 1, wherein one end of the high-frequency signal line is close to an input end of the laser chip, the high-frequency signal line extending to a side of the substrate close to the other side of the first reference ground; a first branch and a second branch are arranged on the other side of the first reference ground, and the first branch and the second branch are respectively electrically connected with the first reference ground; the first branch is disposed at one side of the high-frequency signal line, and the second branch is disposed at the other side of the high-frequency signal line.

8. The optical module of claim 7, wherein the second branch is proximate to a first side of the substrate, the first side having a metal layer disposed thereon, the second branch electrically connecting the metal layer.

9. The optical module according to claim 7, wherein a fifth preset gap is provided between the first branch and the high-frequency signal line, a sixth preset gap is provided between the second branch and the high-frequency signal line, and the fifth preset gap and the sixth preset gap are equal.

10. A laser assembly, comprising:

a substrate on a top surface of which a first reference ground, a high frequency signal line and a matching circuit are disposed, the high frequency signal line being disposed at one side of the first reference ground, the matching circuit being disposed at the other side of the first reference ground and the matching circuit being electrically connected to the first reference ground;

the laser chip is arranged on the first reference ground in a mounting mode, and the input end of the laser chip is connected with the high-frequency signal wire in a routing mode and the matching circuit in a routing mode;

the matching circuit comprises a first bonding pad, a second bonding pad, a third bonding pad, a first resistor, an inductor and a capacitor; the input end of the laser chip is connected with the first bonding pad in a routing way, one end of the first resistor is electrically connected with the first bonding pad, and the other end of the first resistor is electrically connected with the second bonding pad; one end of the inductor is electrically connected with the second bonding pad, and the other end of the inductor is electrically connected with the third bonding pad; one end of the capacitor is electrically connected with the third bonding pad, and the other end of the capacitor is electrically connected with the first reference ground; the inductor is used for compensating the low impedance characteristic of the capacitor and improving the bandwidth of the laser chip through inductance compensation.

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