CN212083738U

CN212083738U - Optical module

Info

Publication number: CN212083738U
Application number: CN202020885055.6U
Authority: CN
Inventors: 李丹; 付孟博; 傅钦豪; 谢一帆; 王腾飞
Original assignee: Hisense Broadband Multimedia Technology Co Ltd
Current assignee: Hisense Broadband Multimedia Technology Co Ltd
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-12-04
Anticipated expiration: 2030-05-22

Abstract

The application provides an optical module, through the optical platform who regards the base plate as bearing the weight of the device, its upper surface sets up the gasket, and wherein, the gasket includes insulating heat-conducting layer, lays in the earthing metal layer and the high-speed signal line of insulating heat-conducting layer upper surface, fixes the negative pole of laser chip on above-mentioned earthing metal layer, and the positive pole passes through the routing and is connected with the high-speed signal line electricity. In addition, the high-speed signal wire of the gasket is connected with the circuit board through a routing wire, so that an electric signal from the circuit board can be transmitted to the light receiving chip, the light emitting function of the optical module is realized, meanwhile, the lower surface of the end part of the circuit board is fixed on the substrate, the stability of the relative position of the gasket and the circuit board can be ensured, and the performance stability of the device is ensured. Therefore, the substrate is used for replacing the existing shell, the structure is simple, the material cost of the light emitting secondary light mode is effectively reduced, and the substrate is of an open structure, so that the problem of difficult packaging due to small space can be solved.

Description

Optical module

Technical Field

The application relates to the technical field of optical communication, in particular to an optical module.

Background

The optical communication technology can be applied to novel services and application modes such as cloud computing, mobile internet, video and the like. The optical module realizes the function of photoelectric conversion in the technical field of optical communication, and is one of key devices in optical communication equipment.

A light emitting portion is generally provided in the optical module for emission of an optical signal. In order to fix the relevant components for light emission, the light emitting portion generally includes a cover plate and a cavity. When the module is packaged, firstly, components such as a semiconductor refrigerator, a light emitting chip, a lens and the like are fixed in a cavity, and in addition, a circuit board or a flexible board is inserted into the cavity from an opening of one side wall of the cavity so as to realize the electric connection between the circuit board and the light emitting chip; then, the cover plate covers the cavity from the upper side, and the cover plate and the cavity are fixed together through a resistance welding mode or glue.

However, with the improvement of the communication rate of the optical module, more and more devices need to be arranged in the cavity of the light emitting part, and the optical module is more and more miniaturized at present, and the requirement on the overall dimension of the devices is smaller and better. Therefore, the space in the cavity of the light emitting section is very small, which results in inconvenience in production operation.

SUMMERY OF THE UTILITY MODEL

To the problem that the shell structure in the existing light emission part is complex and the packaging process difficulty is high, the embodiment provides an optical module.

The optical module provided by the embodiment mainly includes:

an upper housing and a lower housing;

a circuit board disposed between the upper case and the lower case;

a substrate, a lower surface of which is in contact with the lower housing, and a lower surface of an end portion of the circuit board is disposed on an upper surface of the end portion of the substrate;

the gasket is arranged on the upper surface of the substrate and comprises an insulating heat conduction layer, a grounding metal layer and a high-speed signal wire, wherein the grounding metal layer is arranged on the upper surface of the insulating heat conduction layer; the end part of the high-speed signal wire is electrically connected with the circuit board through a routing wire and is used for transmitting the electric signal from the circuit board to the laser chip;

the cathode of the laser chip is fixed on the grounding metal layer, and the anode of the laser chip is electrically connected with the high-speed signal wire through a routing wire and used for emitting optical signals based on the electric signals.

It can be seen from the above embodiments that, in this embodiment, the substrate is used as an optical platform for supporting the device, and the gasket is disposed on the upper surface of the substrate, where the gasket includes an insulating heat conduction layer, a ground metal layer disposed on the upper surface of the insulating heat conduction layer, and a high-speed signal line, and the cathode of the laser chip is fixed on the ground metal layer, and the anode of the laser chip is electrically connected to the high-speed signal line through a wire bonding. In addition, the high-speed signal wire of the gasket is connected with the circuit board through a routing wire, so that an electric signal from the circuit board can be transmitted to the light receiving chip, the light emitting function of the optical module is realized, meanwhile, the lower surface of the end part of the circuit board is fixed on the substrate, the stability of the relative position of the gasket and the circuit board can be ensured, and the performance stability of the device is ensured. Therefore, the substrate is used for replacing the existing shell, the structure is simple, the material cost of the light emitting secondary light mode is effectively reduced, and the substrate is of an open structure, so that the problem of difficult packaging due to small space can be solved.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.

Fig. 1 is a schematic diagram of a connection relationship of an optical communication terminal;

FIG. 2 is a schematic diagram of an optical network unit;

fig. 3 is a schematic structural diagram of an optical module provided in an embodiment of the present application;

fig. 4 is an exploded structural schematic diagram of an optical module provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of a light emitting portion and a circuit board according to an embodiment of the present disclosure;

fig. 6 is an exploded schematic view of a light emitting portion and a circuit board according to an embodiment of the present disclosure;

fig. 7 is an exploded view of a light emitting section according to an embodiment of the present application;

fig. 8 is a schematic view of an assembly structure of a light emitting portion according to an embodiment of the present application;

FIG. 9 is an enlarged partial view of area A of FIG. 8;

fig. 10 is an exploded view of the wire bonding protection component and the circuit board according to the embodiment of the present disclosure;

fig. 11 is a schematic structural diagram of a wire bonding protection component according to an embodiment of the present application;

fig. 12 is a top view of a circuit board and a light emitting portion according to an embodiment of the present disclosure;

fig. 13 is a side view of a circuit board and a light emitting portion according to an embodiment of the present application;

FIG. 14 is an enlarged view of portion B of FIG. 13;

fig. 15 is a schematic structural diagram of a substrate according to an embodiment of the present disclosure;

fig. 16 is a plan view of a light emitting portion provided in the present embodiment;

FIG. 17 is a schematic view of a first disassembled structure of the isolator, the transmission enhancement sheet and the fiber optic adapter according to the embodiment of the present application;

FIG. 18 is a schematic diagram illustrating a second disassembled structure of the spacer, the transmission enhancement sheet and the fiber optic adapter according to an embodiment of the present application;

FIG. 19 is a first block diagram of a focusing lens and a fiber optic adapter according to an embodiment of the present disclosure;

FIG. 20 is a second structural diagram of a focusing lens and a fiber optic adapter according to an embodiment of the present disclosure;

fig. 21A is a schematic view of an optical path structure of a light emitting portion provided in the prior art;

FIG. 21B is a simulation diagram of the coupling efficiency of the optical path structure shown in FIG. 21A;

FIG. 22A is a schematic diagram of the optical path structure of a light emitting part provided in the prior art;

FIG. 22B is a simulation diagram of the coupling efficiency of the optical path structure shown in FIG. 22A;

FIG. 23 is a graph showing the coupling efficiency of an optical axis passing through the center of a second lens and entering a tilted fiber ferrule;

fig. 24A is a schematic view of an optical path structure of a light emitting portion according to an embodiment of the present application;

fig. 24B is a simulation diagram of the coupling efficiency of the optical path structure in fig. 24A.

Detailed Description

The technical solutions in the embodiments will be described clearly and completely with reference to the drawings in the embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present invention.

One of the core elements of fiber optic communications is the conversion of optical to electrical signals. The optical fiber communication uses the optical signal carrying information to transmit in the optical fiber/optical waveguide, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of the light in the optical fiber. The information processing devices such as computers use electrical signals, which require the interconversion between electrical signals and optical signals during the signal transmission process.

The optical module realizes the photoelectric conversion function in the technical field of optical fiber communication, and the interconversion of optical signals and electric signals is the core function of the optical module. The optical module is electrically connected with an external upper computer through a golden finger on a circuit board, main electrical connections comprise power supply, I2C signals, data signal transmission, grounding and the like, the electrical connection mode realized by the golden finger becomes a standard mode of the optical module industry, and on the basis, the circuit board is a necessary technical characteristic in most optical modules.

Fig. 1 is a schematic diagram of connection relationship of an optical communication terminal. As shown in fig. 1, the connection of the optical communication terminal mainly includes an optical network unit 100, an optical module 200, an optical fiber 101, and a network cable 103;

one end of the optical fiber is connected with the far-end server, one end of the network cable is connected with the local information processing equipment, and the connection between the local information processing equipment and the far-end server is completed by the connection between the optical fiber and the network cable; and the connection between the optical fiber and the network cable is completed by an optical network unit with an optical module.

An optical port of the optical module 200 is connected with the optical fiber 101 and establishes bidirectional optical signal connection with the optical fiber; the electrical port of the optical module 200 is accessed into the optical network unit 100, and establishes bidirectional electrical signal connection with the optical network unit; the optical module realizes the mutual conversion of optical signals and electric signals, thereby realizing the connection between the optical fiber and the optical network unit; specifically, the optical signal from the optical fiber is converted into an electrical signal by the optical module and then input to the optical network unit 100, and the electrical signal from the optical network unit 100 is converted into an optical signal by the optical module and input to the optical fiber. The optical module 200 is a tool for realizing the mutual conversion of the photoelectric signals, and has no function of processing data, and information is not changed in the photoelectric conversion process.

The optical network unit is provided with an optical module interface 102, which is used for accessing an optical module and establishing bidirectional electric signal connection with the optical module; the optical network unit is provided with a network cable interface 104 for accessing a network cable and establishing bidirectional electric signal connection with the network cable; the optical module is connected with the network cable through the optical network unit, specifically, the optical network unit transmits a signal from the optical module to the network cable and transmits the signal from the network cable to the optical module, and the optical network unit is used as an upper computer of the optical module to monitor the work of the optical module.

At this point, a bidirectional signal transmission channel is established between the remote server and the local information processing device through the optical fiber, the optical module, the optical network unit and the network cable.

Common information processing apparatuses include routers, switches, electronic computers, and the like; the optical network unit is an upper computer of the optical module, provides data signals for the optical module, and receives the data signals from the optical module, and the common upper computer of the optical module also comprises an optical line terminal and the like.

Fig. 2 is a schematic diagram of an optical network unit structure. As shown in fig. 2, the optical network unit 100 includes a circuit board 105, and a cage 106 is disposed on a surface of the circuit board 105; an electric connector is arranged in the cage 106 and used for connecting an electric port of an optical module such as a golden finger; the cage 106 is provided with a heat sink 107, and the heat sink 107 has a convex structure such as a fin for increasing a heat radiation area.

The optical module 200 is inserted into an optical network unit, specifically, an electrical port of the optical module is inserted into an electrical connector in the cage 106, and an optical port of the optical module is connected with the optical fiber 101.

The cage 106 is positioned on the circuit board, enclosing the electrical connectors on the circuit board in the cage; the optical module is inserted into the cage, the cage fixes the optical module, and heat generated by the optical module is conducted to the cage through the optical module housing and finally diffused through the heat sink 107 on the cage.

Fig. 3 is a schematic structural diagram of an optical module 200 according to an embodiment of the present disclosure, and fig. 4 is an exploded structural diagram of the optical module 200 according to the present disclosure. As shown in fig. 3 and 4, an optical module 200 provided in an embodiment of the present application includes an upper housing 201, a lower housing 202, an unlocking handle 203, a circuit board 30, a light emitting portion 40, and a light receiving portion 50.

The upper shell 201 is covered on the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity is generally a square body, and specifically, the lower tube shell comprises a main plate and two side plates which are positioned on two sides of the main plate and are perpendicular to the main plate; the upper shell comprises a cover plate, and the cover plate covers two side plates of the upper shell to form a wrapping cavity; the upper shell can also comprise two side walls which are positioned at two sides of the cover plate and are perpendicular to the cover plate, and the two side walls are combined with the two side plates to cover the lower shell.

The two openings may be two ends (204, 205) in the same direction, or two openings in different directions; one opening is an electric port 204, and a gold finger of the circuit board extends out of the electric port 204 and is inserted into an upper computer such as an optical network unit; the other opening is an optical port 205 for external optical fiber access to connect the light emitting part 40 and the light receiving part 50 inside the optical module; optoelectronic devices such as the circuit board 30, the light emitting portion 40, and the light receiving portion 50 are located in the package cavity.

The assembly mode of combining the upper shell and the lower shell is adopted, so that the devices such as the circuit board 30, the light emitting part 40, the light receiving part 50 and the like can be conveniently installed in the shells, and the upper shell and the lower shell form an outermost packaging protection shell of the optical module; the upper shell and the lower shell are made of metal materials, so that electromagnetic shielding and heat dissipation are facilitated; generally, the shell of the optical module cannot be made into an integrated structure, so that when devices such as a circuit board and the like are assembled, the positioning component, the heat dissipation structure and the electromagnetic shielding structure cannot be installed, and the production automation is not facilitated.

The unlocking handle 203 is located on the outer wall of the wrapping cavity/lower shell 202 and used for realizing the fixed connection between the optical module and the upper computer or releasing the fixed connection between the optical module and the upper computer.

The unlocking handle 203 is provided with a clamping structure matched with the upper computer cage; the tail end of the unlocking handle is pulled to enable the unlocking handle to move relatively on the surface of the outer wall; the optical module is inserted into a cage of the upper computer, and the optical module is fixed in the cage of the upper computer through a clamping structure of the unlocking handle; by pulling the unlocking handle, the clamping structure of the unlocking handle moves along with the unlocking handle, so that the connection relation between the clamping structure and the upper computer is changed, the clamping relation between the optical module and the upper computer is relieved, and the optical module can be drawn out from the cage of the upper computer.

The circuit board 30 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as the microprocessor MCU2045, the laser driver chip, the limiting amplifier, the clock data recovery CDR, the power management chip, and the data processing chip DSP).

The circuit board 30 connects the electrical devices in the optical module together according to the circuit design through circuit wiring to realize the electrical functions of power supply, electrical signal transmission, grounding and the like.

The circuit board 30 is generally a rigid circuit board, which can also realize a bearing function due to its relatively hard material, for example, the rigid circuit board can stably bear a chip; the hard circuit board can also be inserted into an electric connector in the upper computer cage, and specifically, a metal pin/golden finger is formed on the surface of the tail end of one side of the hard circuit board and is used for being connected with the electric connector; these are not easily implemented with flexible circuit boards.

A flexible circuit board is also used in a part of the optical module to supplement a rigid circuit board; the flexible circuit board is generally used in combination with a rigid circuit board, for example, the rigid circuit board may be connected to the optical transceiver device through the flexible circuit board.

The optical module further includes a light emitting portion and a light receiving sub-module, which may be collectively referred to as an optical sub-module. As shown in fig. 4, an optical module provided by an embodiment of the present invention includes a light emitting portion 40 and a light receiving portion 50. The light emitting part 40 is configured to convert an electrical signal into an optical signal, and the generated optical signal is transmitted to the outside of the optical module through the optical fiber receptacle 60; the optical receiving portion 50 is used for converting optical signals received by the optical fiber receptacle 60 into electrical signals, and in this embodiment, the optical receiving portion 50 is disposed on the surface of the circuit board 30, and in another common packaging manner, the optical receiving sub-module is physically separated from the circuit board, and is electrically connected through a flexible board.

For some optical modules, the service environment is relatively good, for example, an air conditioner is arranged in a data center to control the temperature and the humidity, so that the requirement on the sealing performance of devices is not high, and the requirement on the cost of finished products is higher. In addition, aiming at the problem that the light emitting part adopts a packaging mode of a tube shell, the tube shell usually adopts machining or die sinking, so the design of the tube shell is relatively complex, the production cost is higher, and in the process of module packaging, components such as a semiconductor refrigerator, a light emitting chip, a lens and the like need to be fixed in the tube shell, the space in the cavity of the light emitting part is very small, and the production operation is inconvenient. Fig. 5 is a schematic structural diagram of a light emitting portion and a circuit board according to an embodiment of the present disclosure, and fig. 6 is an exploded structural diagram of the light emitting portion and the circuit board according to the embodiment of the present disclosure. As shown in fig. 5 and 6, the light emitting portion 40 in this embodiment is packaged in a non-airtight manner, and is physically separated from the circuit board 30, and is electrically connected by wire bonding of a metal material, for example, by gold wire. In the light emitting section 40, the present embodiment adopts a package in which a substrate is used as an optical platform, and devices such as a laser chip and a semiconductor cooler are mounted on the substrate.

It should be noted that the light emitting portion 40 in this embodiment includes 4 light paths with the same wavelength, and the data transmission rate can be increased by increasing the number of the light paths, and other numbers can be set in other embodiments. In addition, the following examples illustrate the present embodiment by taking one of the optical paths as an example.

Fig. 7 is an exploded structural view of a light emitting section provided in an embodiment of the present application, and fig. 8 is an assembled structural view of the light emitting section provided in the embodiment of the present application. As shown in fig. 7 and 8, in order to reduce the production cost and provide a flat carrying surface for the laser chip, the semiconductor cooler, and the like, the light emitting portion 40 in this embodiment includes a substrate 41 as an optical platform, and a TEC (semiconductor cooler) 42, a spacer 43, a laser chip 44, a collimating lens 45, an isolator 46, an anti-reflection sheet (AR sheet) 47, a fiber adapter 48, and the like are disposed on the upper surface of the substrate 41.

To further facilitate heat dissipation of the components disposed on the upper surface of the substrate 41, the lower surface of the substrate 41 may be fixed to a housing that is optically opened, such as the lower housing 201, by a thermally conductive adhesive. In this way, heat generated by components in the light emitting portion 40 can be conducted to the housing of the optical module through the substrate 41 and then conducted to the outside of the optical module through the housing of the optical module. Further, in consideration of the heat dissipation effect, the processing precision, the thermal expansion and other factors, the substrate 41 is made of tungsten copper, i.e. an alloy of tungsten and copper in the present embodiment, but may be made of other materials, such as ceramic, in other embodiments.

The TEC42 is used to conduct heat generated by the laser chip 44 away from the substrate 41. Specifically, TEC42 includes an upper heat exchange surface and a lower heat exchange surface. The top of the upper heat exchange surface is provided with a gasket 43, and the upper heat exchange surface is used for absorbing heat generated by the laser chip 44 transmitted by the gasket 43. The bottom of the upper heat exchange surface is connected to the lower heat exchange surface, and the lower heat exchange surface is fixed to the upper surface of the substrate 41, so that the substrate 41 can be used to guide the heat of the lower heat exchange surface of the TEC42 to the outside of the optical module.

Fig. 9 is a partially enlarged view of the area a in fig. 8. As shown in fig. 9, the pad 43 in the present embodiment includes an insulating and heat conducting layer 431 and a metalized circuit pattern (also called trace), and the insulating and heat conducting layer 431 may be made of a ceramic material with good heat conductivity, good insulation performance and high processing precision, and certainly is not limited to ceramic. In order to facilitate the mounting of each electrical element on the pad 43, in the present embodiment, the metalized circuit pattern disposed on the upper surface of the insulating and heat conducting layer 431 includes the high-speed signal line 432 and the ground line 433, and the lower surface of the insulating and heat conducting layer 431 is in contact with the upper surface of the TEC 42. The cathode of the laser chip 44 can be fixed on the ground 433 of the pad 43 by welding or conductive glue, and the anode of the laser chip 44 can be connected to the high-speed signal line 432 by wire bonding.

It should be noted that the design shapes and layouts of the high-speed signal line 432 and the ground line 433 are not limited to the manner provided by this embodiment, and in other embodiments, the design may be performed according to the transmission rate of the signal and the requirements of the components and the like to be arranged.

In the working process of the optical module, the high-frequency data electrical signal from the upper computer is transmitted to the clock data recovery chip, the laser driving chip and other chips arranged on the circuit board through the golden finger on the circuit board 30, the high-frequency data electrical signal received by the optical module is subjected to signal shaping, amplitude adjustment and other processing by using the clock data recovery chip, the laser driving chip and other chips, and in order to transmit the shaped high-frequency data electrical signal to the laser chip 44 arranged on the gasket 43, so that the laser chip emits the data optical signal, and in the embodiment, a ground wire and a high-frequency signal wire (not shown in the figure) are also arranged on the circuit board 30. Meanwhile, the high-frequency signal line on the circuit board 30 is connected with the high-speed signal line 432 on the pad 43 through a routing, and the ground wire on the circuit board 30 is connected with the ground wire 433 on the routing pad 43, so that the electric signal from the circuit board 30 can be transmitted to the laser chip 44. It should be noted that the pad 43 may further be provided with components such as a backlight detector, a resistor, a capacitor, and the like, and each component may be electrically connected to the circuit board 30 through a corresponding trace arranged on the pad 45, so as to realize stable light emission of the laser chip 44.

Fig. 10 is an exploded view of the wire bonding protection component and the circuit board according to the embodiment of the present disclosure. As shown in fig. 10, in this embodiment, since the wire bonding diameter between the circuit board 30 and the pad 43 is usually relatively small, the wire bonding length for connecting the high frequency signal lines on the circuit board 30 and the pad 43 is also required in order to prevent the wire bonding from being broken due to the relative position movement between the circuit board 30 and the pad 43, and in consideration of problems such as impedance matching. Therefore, in order to ensure the stability of the relative position between the circuit board 30 and the spacer 43, the present embodiment fixes the lower surface of the end portion of the circuit board 30 close to the substrate 41 to the upper surface of the substrate 41.

Fig. 11 is a schematic structural diagram of a wire bonding protection component according to an embodiment of the present application. As shown in fig. 10 and 11, in order to avoid the wire bonding of the connecting circuit board 30 and the pad 43 being touched, the wire bonding protection component 70 is disposed on the circuit board 30 in this embodiment, in order to prevent the wire bonding protection component 70 from being conductive, it may be made of a non-metal material, for example, a plastic material, and fixed on the circuit board 30 by using a non-conductive glue, and the wire bonding for connecting the pad 43 and the circuit board 30 is covered under the wire bonding protection component 70, so as to avoid the problem of crush, damage, etc. caused by the wire bonding being touched.

Further, in order to facilitate heat dissipation of devices located below the wire bonding protection component 70 and reduce the occupied area of the wire bonding protection component 70 on the circuit board, as shown in fig. 11, in the present embodiment, the wire bonding protection component 70 is configured to be composed of a protection plate 71 and two or more supporting members 72, where the protection plate 71 is a flat plate-shaped structure, and the specific shape of the protection plate 71 can be set according to the layout requirement of the circuit board 30, for example, the protection plate is designed to be an L-shaped structure in the present embodiment. One end of the supporting member 72 is fixedly connected to the lower surface of the protection plate 71, and the other end is non-conductively fixed to the upper surface of the circuit board 30 by glue or the like.

Fig. 12 is a top view of a circuit board and a light emitting portion according to an embodiment of the present disclosure. As shown in fig. 12, since the laser chip 44 and the pad 43 are also connected by wire bonding, in this embodiment, the connection circuit board 30 and the pad 43 are wire-bonded under the protective plate 71 of the wire bonding protective member 70, and the pad 43 is also wire-bonded under the protective plate 71 of the wire bonding protective member 70. In addition, the signals such as the high frequency data signal and the offset signal received by the laser chip 44 need to be processed by a laser driver chip (not shown) disposed on the circuit board 30 and then sent to the laser chip 44, and the laser driver chip is usually electrically connected to the circuit board 30 by wire bonding, so the laser driver chip is disposed close to the pad 43 and disposed under the wire bonding protection component 70 in this embodiment.

Therefore, the present embodiment uses the substrate 41 to replace the existing light emitting part of the housing, the structure is simple, the material cost of the light emitting sub-optical module is effectively reduced, and the upper part of the substrate 41 is an open structure, so that the problem of difficult packaging due to the small space inside the housing can be solved. In addition, the assembly mode between the substrate 41 and the circuit board 30 and the routing protection component 70 are arranged, so that the service performance of the module can be effectively ensured.

Fig. 13 is a top view of a circuit board and a light emitting portion according to an embodiment of the present disclosure, and fig. 14 is an enlarged view of a portion B in fig. 13. As shown in fig. 13 and 14, since the light emitted from the laser chip 44 is divergent light, and the light entrance aperture of the optical fiber is generally small, in order to improve the optical coupling efficiency, the light entrance surface of the focusing lens 45 is disposed toward the light exit surface of the laser chip 44, and the light exit surface of the focusing lens 45 is disposed toward the light entrance surface of the optical fiber adapter 48. The light emitted from the laser chip 44 is coupled as divergent light into the optical fiber in the fiber adapter 48 by the focusing lens 45. Since the light entrance aperture of the optical fiber is generally small, in order to ensure the optical coupling efficiency, the present embodiment adjusts the position of the focusing lens 45 so that the focal point of the focusing lens 45 is located near the end face of the optical fiber in the fiber stub 803.

In addition, in order to make the light converged by the focusing lens 45, the directions of the optical axes before and after the light is converged are not changed, that is, the light is incident along the center of the focusing lens, the incident direction can ensure that the converged light keeps the distribution of the mode spots before the light is converged to the maximum extent, the regular circular light spots are presented, and the efficiency is improved in the subsequent coupling process. Therefore, in this embodiment, the light emitted from the laser chip 44 enters along the center of the focusing lens 45, specifically, the light is converged through the center of the focusing lens, ideally, the center of the light beam emitted from the laser chip 44 passes through the optical axis of the focusing lens 45, so in order to achieve the alignment between the laser chip 44 and the focusing lens 45, and combine the existing lens and the size characteristics of the laser chip, the focusing lens 45 is disposed on the upper surface of the TEC42, that is, the gasket 43 is used to compensate the height difference between the laser chip 44 and the focusing lens 45.

Since the light entrance aperture of the optical fiber is generally small, the stability of the relative position between the focusing lens 45 and the fiber adapter 48 is also important. For the above reason, the present embodiment also fixes the fiber adapter 48 on the upper surface of the substrate 41. In order to make the light emitted from the focusing lens 45 enter the optical fiber of the optical fiber distributor 48 more, the optical axes of the focusing lens 45 and the optical fiber distributor 48 are ideally at the same level or approximately at the same level.

Fig. 15 is a schematic structural diagram of a substrate according to an embodiment of the present application. As shown in fig. 15, in order to achieve alignment between the focusing lens 45 and the optical fiber guide 48, the present embodiment further designs the substrate 41, wherein a recess 412 is formed in a central region of the substrate 41, so that the upper surface of the substrate 41 is divided into a first upper surface 411 and a second upper surface 413 by the recess 412, and the first upper surface 411 and the second upper surface 413 are respectively located at two sides of the recess 412.

The first upper surface 411 is used for fixedly connecting with the lower surface of the end part of the circuit board 30; a second upper surface 413 for mounting a fiber optic adapter 48; the recessed portion 412 is used for arranging the semiconductor refrigerator 42, wherein the lower surface of the semiconductor refrigerator 42 is in contact with the bottom of the recessed portion, the upper surface of the semiconductor refrigerator 42 is provided with a gasket 43 and a focusing lens 45, the upper surface of the gasket 43 is provided with a laser chip 44, so that the upper surface of the gasket 43 and the upper surface of the circuit board 30 are in the same horizontal plane or approximately in the same horizontal plane, wire bonding is facilitated, and in addition, the optical axis of the optical fiber adapter 48 and the optical axis of the focusing lens 45 can be in the same horizontal plane or approximately in the same horizontal plane, so that optical coupling efficiency is improved. In this embodiment, the substrate 41 is configured to have a recessed portion, so that not only the bearing function thereof is realized, but also the alignment function between the devices is effectively realized.

As shown in fig. 14, in order to isolate the reflected light in the optical path, an isolator 46 is usually provided on the light outgoing side of the present embodiment. The present embodiment arranges the isolator 46 on the light exit side of the focusing lens 45 based on the characteristic that the light emitted from the laser chip 44 is divergent light, and in addition, arranges the isolator 46 on the second upper surface 413 of the substrate 41 based on the reason that the space available on the TEC42 is small, and the like.

The isolator 46 in this embodiment is based on the polarization principle of passing light, allowing light to pass only in a single direction. Based on the working principle of the isolator 46, the coupling power of the laser chip 44 and the isolator 46 is adjusted by adjusting the included angle between the polarization direction of the laser emitted by the laser chip and the polarization direction of the isolator 46, so that the output light power of the optical module can be controlled.

In addition, for a high-speed optical module, for example, a 400G product, which puts higher requirements on optical power coupling efficiency, light enters an optical fiber from air and approximately has 4% of light emission, which causes a loss of coupling efficiency, therefore, the present embodiment further provides an anti-reflection sheet 47 between the isolator 46 and the optical fiber adapter 48, which can effectively reduce end emission at the optical fiber adapter 48.

Fig. 16 is a plan view of a light emitting portion provided in the present embodiment. As shown in fig. 16, in order to reduce the light reflected by the isolator 46 to return to the laser chip 44 and reduce the return loss, the light incident surface normal (or referred to as light incident surface normal) of the isolator 46 and the optical axis of the focusing lens 45 have an included angle θ, which may be set as 5 ° or 10 ° according to the requirement, for example, it is to be noted that the optical axis of the light beam emitted by the laser chip 44 (or referred to as the light emitting direction of the laser chip 44) and the optical axis of the focusing lens 45 are overlapped or approximately overlapped in this embodiment, in other embodiments, they may not be overlapped, and further, the light incident surface normal of the isolator 46 and the optical axis of the focusing lens 45 have an included angle θ, and then the light incident surface normal of the isolator 46 and the optical axis of the light beam emitted by the laser chip 44 have an included.

In this way, the light emitted from the laser chip 44 is focused on the lens 45, the isolator 46, and the transmission increasing sheet 47 in this order, and then is emitted through the air into the optical fiber in the optical fiber adapter 48. If the optical fiber perpendicularly enters the end face of the optical fiber, the angle relationship between the light emitting direction of the laser chip and the optical fiber insertion core is easily controlled by adopting the mode, but the perpendicular incidence can enable the reflected light to return along the original optical path, the returned light returns to the laser chip 44, and the light emitting of the laser chip 44 is further influenced.

Therefore, in order to prevent the reflected light from returning along the original optical path, the optical path is designed to enable the light to be incident on the end face of the optical fiber in a non-perpendicular way; to achieve non-normal incidence of light at the fiber-optic endface, the present embodiment provides the light-incident surface of the fiber-optic adapter 48 as an inclined surface.

Fig. 17 is a schematic view of a first split structure of an isolator, a permeation enhancer sheet, and a fiber optic adapter according to an embodiment of the present application, and fig. 18 is a schematic view of a second split structure of an isolator, a permeation enhancer sheet, and a fiber optic adapter according to an embodiment of the present application. As shown in fig. 17 and 18, based on the above design that the normal line of the light incident surface of the isolator 46 forms an included angle with the optical axis of the focusing lens 45 and the light incident surface of the optical fiber adapter 48 also forms a certain inclination angle, and in order to facilitate fixing the isolator 46, the anti-reflection sheet 47 and the optical fiber adapter 48 on the substrate 41, the embodiment fixes the isolator 46, the anti-reflection sheet 47 and the optical fiber adapter 48 together by using glue, silver glue, or the like, wherein the anti-reflection sheet 47 can be fixed on the light incident end surface of the optical fiber adapter 48, and then the isolator 46 is fixed on the anti-reflection sheet 47. When the module is packaged, the spacer 43, the laser chip 44 and the focusing lens 45 may be mounted in a passive manner, and then, the optical assembly composed of the isolator 46, the anti-reflection sheet 47 and the fiber adapter 48 is actively coupled.

As shown in FIG. 18, the fiber optic adapter 48 is configured by providing an end face thereof with a first angle of inclination θ₁Wherein the inclination angle is equal to the angle between the normal of the end face of the optical fiber adapter 48 and the optical axis of the focusing lens 45, and when the isolator 46 and the optical fiber adapter 48 are attached to each other, the normal of the light incident surface of the isolator 46 and the optical axis of the focusing lens 45 also have the first inclination angle theta₁. In addition, as shown in fig. 18, in the present embodiment, the port 482 for inserting the optical fiber in the optical fiber adapter 48 is provided in a tapered configuration, and when the optical fiber is packaged, the optical fiber is inserted into the optical fiber adapter 48 through the port 482, and then, glue is poured into the tapered port 482, thereby facilitating the fixation of the optical fiber.

In this embodiment, the optical fiber adapter 48 may include an optical fiber ferrule, the optical fiber ferrule is formed by wrapping optical fibers with ceramic cylinders, a central axis of the optical fiber ferrule is the same as a central axis of the optical fiber, and an incident surface of the optical fiber ferrule is ground into an inclined surface, i.e., an incident surface of the optical fiber is ground into the same inclined surface, so that the incident surface of the optical fiber adapter 48 has a certain inclination angle, or the optical fiber adapter 48 is also set into the same inclined surface as the incident surface of the optical fiber. Furthermore, the optical fiber is composed of a core layer and a cladding layer with different refractive indexes, and light is totally reflected at an interface of the core layer and the cladding layer so as to be restrained to be transmitted in the core layer.

The total reflection occurs on the premise that a sufficiently large incident angle is provided. Therefore, the light is totally reflected in the optical fiber, and after the light is refracted at the light incident surface of the optical fiber, the refraction angle is small enough to satisfy the condition that the light has a large enough incident angle when being reflected again in the optical fiber. After refraction, a small enough refraction angle is formed, and when refraction is needed, a small enough incidence angle is formed; in order to achieve better coupling efficiency, the optical axis of the optical fiber is parallel to the central axis of the optical fiber, and the light beam entering the optical fiber is symmetrical about the central axis. Therefore, the light incident on the light incident surface of the optical fiber has a specific incident angle range.

After the light incident surface of the optical fiber adapter 48 is set to have a certain inclination angle, the light beam converged by the focusing lens 45, especially the light beam near the optical axis, is incident into the light incident surface of the optical fiber in a non-vertical direction, the incident angle is increased, the refraction angle is also increased, and the light entering the optical fiber is not favorable for total reflection at the interface between the core layer and the cladding layer of the optical fiber, so that the coupling efficiency is reduced. In view of the above problem, the present embodiment optimizes the placement position of the optical fiber adapter 48 on the substrate 41, so that the optical fiber adapter 48 is obliquely disposed on the substrate 41 in a plane parallel or approximately parallel to the upper surface of the substrate 41, so that the central axis of the optical fiber in the optical fiber adapter 48 is not parallel to the optical axis of the focusing lens 45.

Fig. 19 is a first structural diagram of a focusing lens and a fiber adapter according to an embodiment of the present disclosure. As shown in fig. 19, in the present embodiment, the end face in the fiber optic adapter 48 is set to have the first inclination angle θ₁For example, the angle is set to 7 °, 8 °, and the like, but not limited to this value, and the incident surface of the internal optical fiber (not shown) is adapted to have the first inclination angle θ₁Then, the central axis of the optical fiber adapter 48 is set to have a second inclination angle θ with respect to the optical axis of the focusing lens 45 in the direction along which the end face of the optical fiber adapter 48 is inclined₂For example, it is set to 3 °, 2 °, etc. but not limited to this value.

In addition, in this embodiment, the isolator 46 and the antireflection sheet 47 are fixed to the end face of the optical fiber adapter 48, so that the incident surface of the isolator 46 has an inclination angle θ with respect to the focusing lens 45, that is, an angle θ is formed between a normal of the incident surface of the isolator 46 and the optical axis of the focusing lens 45.

Fig. 20 is a second structural diagram of a focusing lens and a fiber adapter according to an embodiment of the present disclosure. As shown in fig. 20, the optical axis direction of the light beam refracted into the optical fiber can be parallel or nearly parallel to the central axis of the optical fiber by the above arrangement, and the optical coupling efficiency can be further effectively improved.

The following will explain the comparison between the scheme provided in this embodiment and the existing scheme. The light emitted from the laser chip 44 is centrosymmetric about the optical axis, and the light entering the optical fiber is also centrosymmetric about the optical axis, and three typical light rays are illustrated as an example, and the light rays at the optical axis are schematically illustrated.

Fig. 21A is a schematic diagram of an optical path structure of a light emitting portion provided in the prior art, and fig. 21B is a simulation diagram of coupling efficiency of the optical path structure in fig. 21A. As shown in fig. 21A, the focusing lens in the present embodiment is composed of a first lens 45a and a second lens 45 b. The central axis of the optical fiber adapter (not shown in the figure) is parallel to the optical axis direction of the outgoing light beam of the laser chip 44, the central axis of the optical fiber adapter is set to be parallel to the central axis of the optical fiber ferrule (not shown in the figure), and the central axis of the optical fiber ferrule is parallel to the central axis of the optical fiber 481 in the optical fiber ferrule (ideally, coincident). The divergent light emitted from the laser chip 44 is converged into parallel light by the first lens 45a, and the parallel light is converged by the second lens 45b and then incident on the incident surface of the optical fiber 481. The light after twice convergence keeps the original optical axis direction, the light spot shape is unchanged, and the light spot is a circular light spot in an ideal state. The converged light meets the angle requirement of total reflection of the optical fiber, and the optical axis of the converged light is perpendicular to the light incident surface of the optical fiber. As shown in fig. 21B, the light is converged through the center of the focusing lens, the converged light is coupled into the optical fiber 481, most of the light is transmitted through the optical fiber, less light is distributed around the optical fiber, and the optical path structure of fig. 21A achieves higher coupling efficiency.

The optical axis is perpendicular to the light-incident surface, and the refraction that occurs at this time has the smallest angle of incidence (0 °) and the smallest angle of refraction. The optical path design adopted in fig. 21A can meet the angle requirement of total reflection of the optical fiber, and the light spot shape is also favorable for optical coupling, but the reflected light generated at the light incident surface of the optical fiber returns along the original optical path, thereby affecting the light emission of the laser chip 44.

Therefore, the optical path design shown in fig. 21A and 21B has the advantages that the center of the focusing lens is used for light path convergence, so that a good spot mode can be maintained, and the disadvantage is that the reflected light generated by the light incident surface of the optical fiber returns to the laser chip along the original optical path.

Fig. 22A is a schematic diagram of an optical path structure of a light emitting portion provided in the prior art, and fig. 22B is a simulation diagram of coupling efficiency of the optical path structure in fig. 22A. In a plan view, the inclination direction of the optical fiber slope is different only in view angle, the optical fiber is cylindrical, and the inclination direction of the slope is different when viewed from a rotational view angle. As shown in fig. 22A, the central axis of the optical fiber 481 is parallel to the direction of the light-emitting optical axis of the laser chip 44, the divergent light emitted by the laser chip 44 is converged into parallel light by the first lens 45a, and the parallel light is converged by the second lens 45b and then enters the light-entering surface of the optical fiber 481. To prevent the reflected light from being reflected back to the laser chip reversibly, the light incident surface of the optical fiber 481 is an inclined surface. In order to make the light entering the optical fiber satisfy the condition of total reflection by using the refraction principle, the light enters the non-central position of the second lens 45b, the light is converged by the non-central position of the second lens 45b, and the light enters the light incident inclined plane of the optical fiber 481 after the optical axis direction of the light is changed by the second lens 45 b; light refraction occurs at the entrance ramp to inject into the optical fiber 481.

As shown in fig. 22A, compared to fig. 21A, since the light incident surface of the optical fiber is an inclined surface and the central axis of the optical fiber in the optical fiber ferrule is not changed, the convergent light certainly cannot maintain the propagation direction of fig. 21A in order to satisfy the total reflection condition of the refracted light. Specifically, if the optical axis remains in the direction shown in fig. 21A and is parallel to the light-emitting optical axis of the laser chip, the light enters the light-entering surface of the light ray in a non-perpendicular direction, the incident angle decreases, the refraction angle also decreases, and the total reflection is not facilitated. In order to increase the incident angle, the optical axis direction in fig. 21A is changed in the scheme of fig. 22A, and the optical axis direction converged by the second lens 45b is not parallel to the light-emitting optical axis direction of the laser chip to increase the incident angle at the time of refraction.

As can be seen from the simulation diagram in fig. 22B, the direction of the optical axis of the light condensed by the second lens 45B is changed so that the condensed light has a different propagation direction from that in fig. 21B, and the light is condensed by the non-central position of the second lens 45B. In order to achieve total reflection of the light, the light incident on the light incident surface of the optical fiber 481 has a specific incident angle range, which also defines the light condensed by the second lens 45b, and cannot be condensed through the center of the second lens 45 b.

However, with the optical path design shown in fig. 22A, the optical axis does not pass through the center of the second lens 45b, and the direction of the optical axis is changed after the light passes through the second lens 45b, the light spot is greatly deformed, the shape of the light spot is distorted, the mode field distribution of the light spot is irregular, and the efficiency of coupling into the optical fiber is obviously reduced.

The optical path design shown in fig. 22A and 22B has the advantage of preventing the reflected light generated at the light incident surface of the optical fiber from returning to the laser chip along the original optical path, and has the disadvantage that the optical path convergence is not performed by using the center of the second lens 45B, and the form of the converged spot mode is greatly deteriorated.

FIG. 23 is a graph illustrating the coupling efficiency simulation of the optical axis passing through the center of the second lens into the tilted fiber stub. As shown in fig. 23, the light incident surface of the optical fiber 481 is an inclined surface, and light emitted from the laser chip 44 is collimated by the first lens 45a, and then converged by the second lens 45b and incident into the optical fiber 481 of the optical fiber adapter; the light is converged through the center of the second lens 45b, the central axis of the optical fiber is parallel to the light of the second lens 45b, the light is refracted and then coupled into the optical fiber 481, a large amount of light can be seen to be emitted from the optical fiber 481 of the optical fiber adapter, and the coupling efficiency is low.

Fig. 24A is a schematic diagram of an optical path structure of a light emitting portion according to an embodiment of the present application, and fig. 24B is a simulation diagram of coupling efficiency of the optical path structure in fig. 24A. As shown in fig. 24A, in this embodiment, the central axis of the optical fiber 481 is parallel to the central axis of the optical fiber adapter, the central axis of the optical fiber adapter is not parallel to the light-emitting optical axis of the laser chip, and the light-emitting optical axis of the laser chip is not parallel to the central axis of the optical fiber; the divergent light emitted from the laser chip 44 is converged into parallel light by the first lens 45a, and the parallel light is converged by the second lens 45b and then incident on the inclined surface of the optical fiber 481.

In order to prevent reflected light from being reflected back to the laser chip reversibly, the light incident surface of the optical fiber is an inclined surface; in order to inject light into the optical fiber by using the refraction principle, the light emitted from the laser chip is injected through the center of the second lens 45b, the original optical axis direction is not changed during the focusing process, and the light is refracted and injected into the optical fiber 481 through the light injection surface of the optical fiber 481 when injected into the inclined surface light injection surface of the optical fiber 481. The signal light is refracted by the inclined plane to enter the optical fiber 481, and the inclination angle of the inclined plane and the inclination angle of the optical fiber adapter are cooperatively controlled, so that the optical axis direction of the signal light refracted to enter the optical fiber 481 is parallel or nearly parallel to the central axis of the optical fiber 481.

Fig. 24A provides a light path design, which aims to maintain a good spot mode after light is converged, and match with the light incident slope of the optical fiber 481, so that the direction of the optical axis of the signal light refracted into the optical fiber 481 is parallel to the central axis of the optical fiber 481, thereby achieving high-efficiency coupling of light into the optical fiber.

In order to keep the light in a better spot mode shape after the light is converged, the light is converged through the center of the second lens 45b, the light is emitted through the center of the second lens 45b, the direction of the focused optical axis is not changed, the converged light keeps the spot shape before the light is converged, and the circular spot shape can be kept under an ideal body, so that the light coupling efficiency is improved.

In order to prevent the reflected light generated by the fiber incident surface from returning to the laser chip along the original optical path, the incident surface of the fiber ferrule/the incident surface of the fiber are designed to be an inclined surface, however, the optical path structure shown in fig. 21A indicates that when the light is converged through the center of the second lens 45b, the subsequent fiber incident surface matched with the second lens cannot be an inclined surface, so that the light refracted at the incident surface can be transmitted by total reflection; the optical path structure shown in fig. 22A shows that when the light incident surface is a slant surface, the light matched with the slant surface cannot be converged through the center of the second lens 45b, so that the light refracted at the light incident surface can be transmitted by total reflection.

In order to make the light coupled into the optical fiber totally reflect, the embodiment of the present application provides a new structural design, and the optical fiber adapter 48 is tilted on the substrate 41, so that the central axis of the optical fiber 481 is not parallel to the light emitting direction of the laser chip, and further the optical fiber tilts by a certain angle relative to the light emitting direction of the laser chip.

The refraction of light into the fiber has a specific angular relationship with the central axis of the fiber, which is exactly the same in fig. 21A, 22A and 24A, which is a necessary requirement for the total emission of light in the fiber.

As shown in fig. 24B, with the optical path structure of fig. 24A, light is converged through the center of the second lens 45B, the light incident surface of the optical fiber is an inclined surface, light converged by the second lens 45B can be efficiently coupled into the optical fiber, and most of the light enters the optical fiber.

In fig. 22A and 24A, the angle of light incidence is the same and the angle after light refraction is the same, with reference to the fiber incidence slope. The difference lies in that: in fig. 22A, the central axis of the optical fiber is parallel to the light emitting direction of the laser chip, and the optical axis passes through the non-central region of the second lens 45 b; in fig. 24A, the central axis of the optical fiber is not parallel to the light emitting direction of the laser chip, and the optical axis passes through the central region of the second lens 45 b. Further, the optical path design provided by the embodiment of the present application realizes that the optical axis direction of the signal light refracted to enter the optical fiber 481 is parallel to the central axis of the optical fiber, thereby completing the high-efficiency coupling of light into the optical fiber.

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

Claims

1. A light module, comprising:

an upper housing and a lower housing;

a circuit board disposed between the upper case and the lower case;

2. The optical module according to claim 1, wherein the substrate has a recess formed therein, and the upper surface of the substrate includes a first upper surface and a second upper surface respectively located on both sides of the recess, wherein:

the lower surface of the circuit board end is arranged on the first upper surface;

a semiconductor refrigerator is arranged in the depressed part, the lower surface of the semiconductor refrigerator is in contact with the bottom of the depressed part, the upper surface of the semiconductor refrigerator is provided with the gasket, and the upper surface of the gasket and the upper surface of the circuit board are positioned on the same horizontal plane or approximately positioned on the same horizontal plane;

and an optical fiber adapter is arranged on the second upper surface, and the optical axis of the optical fiber adapter and the optical axis of the light beam emitted by the laser chip are positioned on the same horizontal plane or approximately positioned on the same horizontal plane.

3. The optical module according to claim 2, characterized in that the upper surface of the semiconductor refrigerator is further provided with a focusing lens, wherein:

the focusing lens is arranged on a transmission light path of a light beam emitted by the laser chip and used for converging the light beam to the optical fiber adapter.

4. The light module of claim 2, wherein the second upper surface further comprises an isolator and a transmission increasing sheet, wherein:

the anti-reflection sheet is attached to the end face of the optical fiber adapter, and the isolator is attached to the anti-reflection sheet.

5. The light module of claim 1, further comprising:

and the routing protection component is fixed on the upper surface of the circuit board in a non-conductive manner and covers the gasket and the routing connecting the gasket and the circuit board.

6. The optical module of claim 5, wherein the wire bonding protection component comprises a protection plate, two or more than two supports, wherein:

one end of the supporting piece is fixed on the upper surface of the circuit board in a non-conductive manner, and the other end of the supporting piece is fixedly connected with the lower surface of the protection plate;

the gasket and a routing wire for connecting the gasket and the circuit board are arranged below the protective plate.

7. The optical module according to claim 4 or 5, wherein a laser driving chip is further disposed on the circuit board, wherein:

the laser driving chip is electrically connected with the circuit board through a routing;

the routing protection component is also covered on the laser driving chip.

8. The optical module according to claim 1, wherein a lower surface of the substrate is fixed to a housing of the optical module by a thermally conductive adhesive.

9. The optical module according to any one of claims 1 to 6, wherein the substrate is a tungsten copper substrate.