An optical module

Abstract

The application discloses an optical module, comprising a silicon optical chip, the silicon optical chip comprising a silicon substrate, an optical coupler arranged on the silicon substrate, first and second input waveguides connected with the optical coupler, first and second coupling waveguides, a PN type doped region connected with the first and second coupling waveguides, a Ge absorption region connected with the PN type doped region, and a metal electrode arranged on the silicon substrate, the first coupling waveguide is connected with the first input waveguide, the second coupling waveguide is connected with the second input waveguide, the thickness size of the first and second coupling waveguides is smaller than that of the first and second input waveguides; the PN type doped region is arranged on the first and second coupling waveguides, the Ge absorption region is arranged above the PN doped region, the Ge absorption region is used for absorbing optical signals and converting the optical signals into electrical signals; the metal electrode is in contact with the PN type doped region and is used for transmitting the electrical signals. The application simultaneously realizes high modulation bandwidth and high optical responsivity through a special waveguide structure and a Ge detector design.

Description

[0001] This application is a divisional application of the application with application number 202110118787.1 and the title of "Optical module and manufacturing method of silicon optical chip", which was filed on January 28, 2021. TECHNICAL FIELD

[0002] The present application relates to the field of optical communication technology, in particular to an optical module. BACKGROUND

[0003] With the development of cloud computing, mobile Internet, video and other new business and application modes, the development and progress of optical communication technology becomes increasingly important. In optical communication technology, the optical module is a tool for converting optical signals and electrical signals, and is one of the key devices in optical communication equipment. With the development of optical communication technology, the transmission rate of the optical module is continuously improved.

[0004] Silicon optical integration technology can integrate modulators, detectors and passive waveguide devices in the same SOI chip. Because it has the advantages of CMOS compatibility, high integration and low cost, it has been widely used in the field of optical communication. With the development and construction of data centers, high-speed and high-capacity silicon optical integration technology has received widespread attention, and has a huge application scenario in the field of data communication, especially in high-density packaging integration. In the next generation of high-speed optoelectronic integrated chips, a transmission capacity of 200Gbps per wave can be achieved, requiring a device bandwidth of more than 70GHz. In the current silicon optical integration chip, the Ge / Si high-speed detector can achieve a responsivity of 1A / W and a 3dB modulation bandwidth of 40GHz, which cannot meet the application requirements of the next generation of more than 200Gbps per wave.

[0005] To solve this problem, in the current peer group, the thickness of the Ge intrinsic region can be reduced to further improve the bandwidth. Although the bandwidth can be improved, it will also reduce the responsivity, thereby deteriorating the receiving sensitivity. In addition, the responsivity can also be improved by additional wavelength technology to achieve end-face coupling, but the process is relatively complex. SUMMARY

[0006] The present application provides an optical module to solve the problem of insufficient bandwidth and insufficient responsivity of high-speed detectors in the current optical module.

[0007] To solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0008] The embodiments of the present application disclose an optical module, comprising:

[0009] a circuit board;

[0010] a silicon optical chip, electrically connected to the circuit board, for receiving signal light transmitted by an optical fiber and performing electro-optical conversion on the signal light;

[0011] The silicon optical chip comprises:

[0012] a silicon substrate;

[0013] an optical coupler disposed on the silicon substrate, the optical coupler being configured to couple signal light transmitted by the optical fiber to the silicon optical chip;

[0014] a first input waveguide disposed on the silicon substrate, the first input waveguide being connected to a first output end of the optical coupler, the first input waveguide being configured to transmit optical signals received by the optical coupler;

[0015] a first coupling waveguide disposed below the first input waveguide, the first coupling waveguide being connected to an output end of the first input waveguide, the first coupling waveguide having a thickness smaller than that of the first input waveguide and a width at an input end larger than that of the first input waveguide at an output end, the first coupling waveguide being configured to transmit optical signals output by the first input waveguide;

[0016] a second input waveguide disposed on the silicon substrate, the second input waveguide being connected to a second output end of the optical coupler, the second input waveguide being configured to transmit optical signals received by the optical coupler;

[0017] a second coupling waveguide disposed below the second input waveguide, the second coupling waveguide being connected to an output end of the second input waveguide, the second coupling waveguide having a thickness smaller than that of the second input waveguide and a width at an input end larger than that of the second input waveguide at an output end, the second coupling waveguide being configured to transmit optical signals output by the second input waveguide;

[0018] a PN-type doped region disposed on the first coupling waveguide and the second coupling waveguide, the PN-type doped region being connected to the first coupling waveguide and the second coupling waveguide, the PN-type doped region comprising an N-type lightly doped region and a P-type lightly doped region, the N-type lightly doped region and the P-type lightly doped region being disposed in sequence along an optical receiving path, the N-type lightly doped region having an N-type heavily doped region disposed therein, and the P-type lightly doped region having a P-type heavily doped region disposed therein, the PN-type doped region being configured to receive optical signals transmitted by the coupling waveguide;

[0019] A Ge absorption region is disposed above the N-type lightly doped region and the P-type lightly doped region to reduce the thickness of the Ge absorption region; the Ge absorption region is electrically connected with the N-type lightly doped region and the P-type lightly doped region respectively, the N-type heavily doped region and the P-type heavily doped region are both away from the Ge absorption region, the waveguide effective refractive index of the Ge absorption region is greater than the effective refractive index of the first coupling waveguide and the second coupling waveguide; the Ge absorption region is used for absorbing the transmitted optical signal and converting the optical signal into an electrical signal;

[0020] A metal electrode is disposed on the silicon substrate, the metal electrode includes an N-region metal electrode and a P-region metal electrode, the N-region metal electrode is in contact with the N-type heavily doped region, and the P-region metal electrode is in contact with the P-type heavily doped region; the metal electrode is used for transmitting the electrical signal.

[0021] The optical module provided in the application comprises a circuit board and a silicon optical chip electrically connected with the circuit board, the silicon optical chip is used for receiving signal light transmitted by an optical fiber and performing electro-optical conversion on the signal light; wherein the silicon optical chip comprises a silicon substrate, an optical coupler, a first input waveguide, a first coupling waveguide, a second input waveguide, a second coupling waveguide, a PN type doped region, a Ge absorption region and a metal electrode, the optical coupler is arranged on the silicon substrate and is used for coupling the signal light transmitted by the optical fiber to the silicon optical chip; the first input waveguide is arranged on the silicon substrate, the first input waveguide is electrically connected with a first output end of the optical coupler, and the first input waveguide is used for transmitting the optical signal received by the optical coupler; the second input waveguide is arranged on the silicon substrate, the second input waveguide is connected with a second output end of the optical coupler, and the second input waveguide is used for transmitting the optical signal received by the optical coupler; in this way, the optical coupler divides the received signal light into two parts, one beam of signal light is transmitted into the first input waveguide, and the other beam of signal light is transmitted into the second input waveguide. The first coupling waveguide is arranged below the first input waveguide, the first coupling waveguide is connected with an output end of the first input waveguide, the thickness size of the first coupling waveguide is smaller than the thickness size of the first input waveguide, the width size of the input end of the first coupling waveguide is greater than the width size of the output end of the first input waveguide, and the first coupling waveguide is used for transmitting the optical signal output by the first input waveguide; the second coupling waveguide is arranged below the second input waveguide, the second coupling waveguide is connected with an output end of the second input waveguide, the thickness of the second coupling waveguide is smaller than the thickness of the second input waveguide, the width size of the input end of the second coupling waveguide is greater than the width size of the output end of the second input waveguide, and the second coupling waveguide is used for transmitting the optical signal output by the second input waveguide; the PN type doped region is arranged on the first coupling waveguide and the second coupling waveguide, the PN type doped region is connected with the first coupling waveguide and the second coupling waveguide, the PN type doped region comprises an N type lightly doped region and a P type lightly doped region, the N type lightly doped region and the P type lightly doped region are arranged in sequence along an optical receiving light path, an N type heavily doped region is arranged in the N type lightly doped region, a P type heavily doped region is arranged in the P type lightly doped region, and the PN type doped region is used for receiving the optical signal transmitted by the first coupling waveguide and the second coupling waveguide; the Ge absorption region is arranged above the N type lightly doped region and the P type lightly doped region to reduce the thickness of the Ge absorption region; the Ge absorption region is electrically connected with the N type lightly doped region and the P type lightly doped region respectively, the N type heavily doped region and the P type heavily doped region are both away from the Ge absorption region, the waveguide effective refractive index of the Ge absorption region is greater than the effective refractive index of the first coupling waveguide and the second coupling waveguide, and the Ge absorption region is used for absorbing the transmitted optical signal and converting the optical signal into an electrical signal; the metal electrode is arranged on the silicon substrate, the metal electrode comprises an N region metal electrode and a P region metal electrode, the N region metal electrode is in contact with the N type heavily doped region, the P region metal electrode is in contact with the P type heavily doped region, and the metal electrode is used for transmitting the electrical signal.

[0022] The optical module provided by the embodiment of the application is based on a silicon photon integrated platform, the input waveguide and the coupling waveguide are arranged in upper and lower layers, the Ge absorption region is arranged above the coupling waveguide with a small thickness, so that the thickness of the Ge absorption region can be reduced, the electron moving rate of the electron in the Ge absorption region is improved, and the function of high modulation bandwidth is realized; in addition, the thickness of the coupling waveguide is small, so that the waveguide effective refractive index of the Ge absorption region is greater than the effective refractive index of the coupling waveguide, most of the optical field can be coupled into the Ge absorption region for detection and absorption, and therefore high optical responsivity can be realized; the Ge absorption region adopts a double-end input mode to detect and absorb the optical signal, and the optical responsivity of the optical module can be further improved. Through the special waveguide structure and the Ge detector design, the high modulation bandwidth and the high optical responsivity can be realized at the same time, and no additional complex process is needed.

[0023] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the application. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the application, the drawings needed in the embodiments will be briefly introduced below. Obviously, other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0025] Figure 1 It is a schematic diagram of the connection relationship of the optical communication terminal;

[0026] Figure 2 It is a schematic diagram of the structure of the optical network terminal;

[0027] Figure 3 It is a schematic diagram of the structure of the optical module provided by the embodiment of the application;

[0028] Figure 4 It is an exploded schematic diagram of the optical module provided by the embodiment of the application;

[0029] Figure 5 It is a schematic diagram of the structure of the silicon optical chip in the optical module provided by the embodiment of the application;

[0030] Figure 6 It is Figure 5 It is a sectional view of the positions of A-A', B-B', C-C' and D-D' in the optical module;

[0031] Figure 7 It is a flow chart of the manufacturing method of the silicon optical chip in the optical module provided by the embodiment of the application;

[0032] Figure 8 It is a structure diagram of the manufacturing process of the silicon optical chip in the optical module provided by the embodiment of the application;

[0033] Figure 9 Another structure diagram of a silicon optical chip in an optical module provided by an embodiment of the present application is shown in FIG. 3.

[0034] Figure 10 Another structure diagram of a silicon optical chip in an optical module provided by an embodiment of the present application is shown in FIG. 3.

[0035] Figure 11 Another structure diagram of a silicon optical chip in an optical module provided by an embodiment of the present application is shown in FIG. 3. DETAILED DESCRIPTION

[0036] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should fall within the protection scope of the present application.

[0037] One of the core links of fiber communication is the mutual conversion of optical signals and electrical signals. Fiber communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers / optical waveguides, and the passive transmission characteristics of light in optical fibers / optical waveguides can realize low-cost and low-loss information transmission; and the information processing equipment such as computers uses electrical signals, in order to establish information connection between the information transmission equipment such as optical fibers / optical waveguides and the information processing equipment such as computers, it is necessary to realize the mutual conversion of electrical signals and optical signals.

[0038] The optical module realizes the mutual conversion function of optical signals and electrical signals in the field of fiber communication technology, and the mutual conversion of optical signals and electrical signals is the core function of the optical module. The optical module realizes electrical connection between the external host computer through the gold fingers on the internal circuit board, and the main electrical connection includes power supply, I2C signal, data information and ground, etc.; the electrical connection mode realized by the gold fingers has become the mainstream connection mode in the optical module industry, and the definition of the pins on the gold fingers forms various industry protocols / specifications.

[0039] Figure 1 A connection relationship diagram of an optical communication terminal is shown in FIG. 1. As shown in FIG. 1, the connection of the optical communication terminal mainly includes the mutual connection among the optical network terminal 100, the optical module 200, the optical fiber 101 and the network cable 103. Figure 1

[0040] ​One end of the optical fiber 101 is connected to a remote server, one end of the network cable 103 is connected to a local information processing device, and the connection between the local information processing device and the remote server is completed by the connection between 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 network terminal 100 with the optical module 200.

[0041] The optical port of the optical module 200 accesses the optical fiber 101 externally, and establishes a bidirectional optical signal connection with the optical fiber 101; the electrical port of the optical module 200 accesses the optical network terminal 100 externally, and establishes a bidirectional electrical signal connection with the optical network terminal 100; the mutual conversion of optical signals and electrical signals is realized inside the optical module, thereby establishing an information connection between the optical fiber and the optical network terminal. Specifically, the optical signal from the optical fiber is converted into an electrical signal by the optical module and then input into the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module and then input into the optical fiber.

[0042] The optical network terminal has an optical module interface 102 for accessing the optical module 200 and establishing a bidirectional electrical signal connection with the optical module 200; the optical network terminal has a network cable interface 104 for accessing the network cable 103 and establishing a bidirectional electrical signal connection with the network cable 103; the connection between the optical module 200 and the network cable 103 is established through the optical network terminal 100. Specifically, the optical network terminal transmits signals from the optical module to the network cable and transmits signals from the network cable to the optical module, and the optical network terminal serves as the upper machine of the optical module to monitor the operation of the optical module.

[0043] At this point, the remote server establishes a bidirectional signal transmission channel with the local information processing device through the optical fiber, the optical module, the optical network terminal, and the network cable.

[0044] Common information processing devices include routers, switches, electronic computers, etc.; the optical network terminal is the upper machine of the optical module, which provides data signals to the optical module and receives data signals from the optical module; common optical module upper machines also include optical line terminals, etc.

[0045] Figure 2 The optical network terminal is a structural schematic diagram. As shown in Figure 2 The optical network terminal 100 has a circuit board 105, and a cage 106 is arranged on the surface of the circuit board 105; an electrical connector is arranged inside the cage 106 for accessing the electrical port of the optical module such as a gold finger; a heat sink 107 is arranged on the cage 106, and the heat sink 107 has a first protrusion part such as fins to increase the heat dissipation area.

[0046] The optical module 200 is inserted into the optical network terminal 100, specifically the electrical port of the optical module is inserted into the electrical connector inside the cage 106, and the optical port of the optical module is connected with the optical fiber 101.

[0047] The cage 106 is located on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged inside the cage; the optical module is inserted into the cage, and the optical module is fixed by the cage; the heat generated by the optical module is conducted to the cage 106, and then diffused through the heat sink 107 on the cage.

[0048] Figure 3 A schematic diagram of an optical module structure is provided for the embodiment of the present application, Figure 4 A schematic diagram of an optical module is provided for the embodiment of the present application. As shown in Figure 3 、 Figure 4 The optical module 200 provided by the embodiment of the present application includes an upper shell 201, a lower shell 202, an unlocking component 203, a circuit board 300 and a silicon optical chip 400.

[0049] The upper shell 201 is combined with the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity generally presents a square body. Specifically, the lower shell 202 includes a main plate and two side plates located on both sides of the main plate and arranged perpendicularly to the main plate; the upper shell includes a cover plate, which is combined with the two side plates of the upper shell to form the wrapping cavity; the upper shell can also include two side walls located on both sides of the cover plate and arranged perpendicularly to the cover plate, which are combined with the two side plates to realize the combination of the upper shell 201 and the lower shell 202.

[0050] The two openings can be two end openings (204, 205) located at the same end of the optical module, or two openings at different ends of the optical module; one of the openings is an electrical port 204, and the gold fingers of the circuit board extend from the electrical port 204 and are inserted into an upper machine such as an optical network terminal; the other opening is an optical port 205 for external fiber access to connect the silicon optical chip 400 inside the optical module; the optoelectronic devices such as the circuit board 300 and the silicon optical chip 400 are located in the wrapping cavity.

[0051] The assembly method of combining the upper shell and the lower shell facilitates the installation of the devices such as the circuit board 300 and the silicon optical chip 400 into the shell, and the upper shell and the lower shell form the outermost packaging protective shell of the module; the upper shell and the lower shell are generally made of metal material, which realizes electromagnetic shielding and heat dissipation; generally, the shell of the optical module is not made into an integral component, so that the positioning components, heat dissipation components and electromagnetic shielding components cannot be installed when assembling the circuit board and other devices, which is not conducive to production automation.

[0052] The unlocking component 203 is located on the outer wall of the wrapping cavity / lower shell 202, and is used to realize the fixed connection between the optical module and the upper machine, or to release the fixed connection between the optical module and the upper machine.

[0053] The unlocking component 203 has a clamping component matched with the cage of the host computer; pulling the end of the unlocking component 203 can relatively move the unlocking component 203 on the surface of the outer wall; the optical module is inserted into the cage of the host computer, and the clamping component of the unlocking component 203 fixes the optical module in the cage of the host computer; by pulling the unlocking component 203, the clamping component of the unlocking component 203 moves, and then the connection relationship between the clamping component and the host computer is changed, so that the clamping relationship between the optical module and the host computer is released, and the optical module can be pulled out of the cage of the host computer.

[0054] The circuit board 300 is provided with circuit traces, electronic components (such as capacitors, resistors, transistors, MOS tubes), and chips (such as MCUs, laser drive chips, limiting amplifier chips, clock data recovery CDR, power management chips, data processing chips DSP), etc.

[0055] The circuit board 300 is used to provide a signal circuit for signal electrical connection, and the signal circuit can provide a signal. The circuit board 300 connects the electrical devices in the optical module according to the circuit design through the circuit traces, so as to realize the functions of power supply, electrical signal transmission, and grounding.

[0056] The circuit board is generally a hard circuit board. Due to the relatively hard material, the hard circuit board can also realize the bearing function, such as the hard circuit board can stably bear the chip; when the optical transceiver assembly is located on the circuit board, the hard circuit board can also provide stable bearing; the hard circuit board can also be inserted into the electrical connector in the cage of the host computer, specifically, a metal pin / gold finger is formed on the surface of one end of the hard circuit board, which is used for connecting with the electrical connector; these are not convenient to realize by the flexible circuit board.

[0057] The flexible circuit board is also used in part of the optical module as a supplement to the hard circuit board; the flexible circuit board is generally used in cooperation with the hard circuit board, such as the flexible circuit board can be used to connect between the hard circuit board and the optical transceiver assembly.

[0058] Silicon optical integration technology can integrate modulators, detectors, and passive waveguide devices in the same SOI chip, and has been widely used in the field of optical communication due to its advantages of compatibility with CMOS, high integration, and low cost. In recent years, with the development and construction of data centers, high-speed and high-capacity silicon optical integration technology has received extensive attention, and has great application prospect in the field of data communication, especially in high-density packaging and integration. In the next generation of high-speed optoelectronic integrated chip, it can realize the transmission capacity of single wave 200Gbps, and requires a device bandwidth greater than 70GHz. In the current silicon optical integration chip, the Ge / Si high-speed detector can realize the responsivity of 1A / W and the 3dB modulation bandwidth of 40GHz, which cannot meet the application requirements of the next generation of single wave 200Gbps or more.

[0059] To solve the problem, in the current peer, the bandwidth can be further improved by reducing the thickness of the Ge intrinsic region, although the bandwidth can be improved, but at the same time, the responsivity is reduced, thereby deteriorating the receiving sensitivity. In addition, the responsivity can also be improved by additional wavelength process to realize end face coupling, but the process is relatively complex.

[0060] To solve the above problems, the embodiments of the present application provide an optical module, which is based on a silicon photonics integrated platform, and integrates an optical coupler, an input waveguide, a coupling waveguide, a PN type doped region, a Ge absorption region and a metal electrode on the silicon photonics integrated platform. The input waveguide and the coupling waveguide are located in the upper and lower layers, and the PN type doped region is made on the coupling waveguide, so as to reduce the thickness of the Ge absorption region, realize the optical modulation bandwidth and high optical responsivity function of the optical module, and without complex waveguide process.

[0061] Figure 5 A structure schematic diagram of a silicon optical chip 400 in an optical module provided by the embodiments of the present application is shown in the figure, Figure 6 For Figure 5 A-A cross-sectional view. As shown in Figure 5 、 Figure 6 The silicon optical chip 400 provided by the embodiments of the present application includes a silicon substrate 410 and a SiO2 layer 420, and the SiO2 layer 420 is arranged above the silicon substrate 410 to facilitate etching on the silicon substrate 410 and the SiO2 layer 420, thereby realizing the reception of signal light.

[0062] The silicon optical chip 400 formed by the silicon substrate 410 and the SiO2 layer 420 is provided with an optical coupler 430, an input waveguide 440, a coupling waveguide 450, a PN type doped region 460, a Ge absorption region 4603 and a metal electrode. The optical coupler 430 is arranged on one side of the silicon substrate 410, and is used to couple the signal light transmitted by the optical fiber 101 to the silicon optical chip 400. Specifically, an optical fiber adapter is arranged between the silicon optical chip 400 and the optical fiber 101, one end of the optical fiber adapter is connected with the optical fiber 101, and the other end is connected with the optical coupler 430 on the silicon optical chip 400. The signal light transmitted by the optical fiber 101 is coupled into the optical coupler 430 through the optical fiber adapter. In the embodiments of the present application, the optical coupler 430 can be a grating coupler, an end face coupler or other optical coupling device.

[0063] The input end of the input waveguide 440 is connected with the output end of the optical coupler 430, and the signal light received by the optical coupler 430 is transmitted in the silicon optical chip 400 through the input waveguide 440. In the embodiment of the present application, the input waveguide 440 adopts a multi-layer or multi-layer vertical waveguide structure design, and utilizes a tapered adiabatic waveguide design, that is, the input end of the input waveguide 440 has a width larger than that of the output end, so that the output end of the input waveguide 440 is tapered, thereby coupling the high-speed optical signal in the external or optical fiber 101 into the silicon optical chip 400 to the coupling waveguide 450.

[0064] The input waveguide 440 is located in the direction of the optical signal receiving light path, and the distance between the boundary on both sides of the input waveguide 440 connected with the coupling waveguide 450 and the center line gradually decreases, thereby forming a tapered structure, and the refractive index remains unchanged. Based on the coupling film theory, when the optical waveguide with a smaller core layer size is coupled into the optical waveguide with a larger core layer size, the coupling efficiency can reach 100%, thereby coupling the high-speed optical signal in the external or optical fiber coupled into the silicon optical chip 400 through the tapered input waveguide into the lower thin coupling waveguide 450 for transmission.

[0065] The coupling waveguide 450 is arranged below the input waveguide 440, and the input end of the coupling waveguide 450 is connected with the output end of the input waveguide 440, and the width size of the input end of the coupling waveguide 450 is larger than that of the output end of the input waveguide 440, so that the optical signal transmitted by the input waveguide 440 can be completely transmitted into the coupling waveguide 450. In the embodiment of the present application, the coupling waveguide 450 is arranged above or below the input waveguide 440, the coupling waveguide 450 is arranged above the input waveguide 440, the thickness size of the coupling waveguide 450 is smaller than that of the input waveguide 440, and the thickness size of the connection between the input waveguide 440 and the coupling waveguide 450 is the same as the thickness size of the input end of the input waveguide 440.

[0066] On the silicon photonics integrated platform, the thickness size of the input end of the input waveguide 440 is generally 220 nm, the thickness size of the connection between the input waveguide 440 and the coupling waveguide 450 is the same as the thickness size of the input end of the input waveguide 440, so that the thickness size of the coupling waveguide 450 is smaller than 220 nm, which can be 90 nm or 130 nm.

[0067] The PN doped region 460 is arranged on the coupling waveguide 450 and electrically connected with the coupling waveguide 450. Specifically, the side of the thin coupling waveguide 450 away from the input waveguide 440 can be a square waveguide, and the PN doped region 460 is arranged on the square waveguide. The PN doped region 460 includes an N-type lightly doped region 4601 and a P-type lightly doped region 4604, and the N-type lightly doped region 4601 and the P-type lightly doped region 4604 are arranged in sequence along the light receiving path. That is, P-type and N-type ion doping are respectively performed in the square waveguide region on one side of the coupling waveguide 450 to form a detector P region and an N region. The P-type and N-type doped regions can be connected to be centrally symmetrically distributed, or can be spaced apart by a certain distance, as long as a PN structure can be formed.

[0068] In the embodiment of the present application, P-type and N-type ion doping are performed in the square waveguide region on one side of the coupling waveguide 450 along the width direction of the silicon optical chip 400. In this way, the input waveguide 440 couples the high-speed optical signal into the coupling waveguide 450 for transmission. When the optical signal is transmitted to the square waveguide region, the N-type lightly doped region 4601 and the P-type lightly doped region 4604 receive the optical signal and cause ion movement.

[0069] The Ge absorption region 4603 is arranged on the PN doped region 460 and electrically connected with the PN doped region 460, and is used for absorbing the transmitted optical signal and converting the optical signal into an electrical signal. Specifically, the Ge absorption region 4603 is arranged above the N-type lightly doped region 4601 and the P-type lightly doped region 4604, and the Ge absorption region 4603 is electrically connected with the N-type lightly doped region 4601 and the P-type lightly doped region 4604, respectively. That is, a Ge thin film is selectively generated above the N-type lightly doped region 4601 and the P-type lightly doped region 4604 as a detector light absorption region. When the optical signal passes through the N-type lightly doped region 4601 and the P-type lightly doped region 4604, it is absorbed by the Ge absorption region 4603 to generate electron-hole pairs. These photo-generated carriers move to both electrodes under the action of an electric field, thereby forming a photo-generated current. The cross-sectional shape of the Ge thin film is a triangle or a trapezoid according to the crystal growth angle requirement, so that the width of the Ge absorption region 4603 can be reduced, thereby forming a very strong electric field strength inside the Ge absorption region 4603 below the N-type lightly doped region 4601 and the P-type lightly doped region 4604, improving the moving speed of the ions, and thus realizing a modulation bandwidth greater than 100 GHz.

[0070] When the thickness of the Ge absorption region 4603 is high, the absorption rate of the ionized particles in the Ge absorption region 4603 is low, so that the modulation bandwidth is low; when the thickness of the Ge absorption region 4603 is low, the absorption rate of the ionized particles in the Ge absorption region 4603 is high, so that the modulation bandwidth is high. In the embodiment of the present application, the Ge absorption region 4603 is arranged on the upper layer of the coupling waveguide 450 and the PN type doped region 460, so that the thickness of the Ge absorption region 4603 can be reduced, so that the modulation bandwidth of the Ge absorption region 4603 can be increased, and a modulation bandwidth greater than 100 GHz can be achieved.

[0071] In addition, due to the small thickness of the coupling waveguide 450, the waveguide effective refractive index of the Ge absorption region 4603 is greater than the effective refractive index of the coupling waveguide 450, so that most of the optical field can be coupled into the Ge absorption region 4603 for detection and absorption under the evanescent wave coupling, and therefore a very high optical responsivity can be achieved.

[0072] In the embodiment of the present application, the connection width of the Ge absorption region 4603 and the N type lightly doped region 4601 and the connection width of the Ge absorption region 4603 and the P type lightly doped region 4604 can be the same, that is, the central axis of the Ge absorption region 4603 coincides with the connection position of the N type lightly doped region 4601 and the P type lightly doped region 4604; the connection width of the Ge absorption region 4603 and the N type lightly doped region 4601 and the connection width of the Ge absorption region 4603 and the P type lightly doped region 4604 can also be different, for example, the connection width of the Ge absorption region 4603 and the N type lightly doped region 4601 is greater than the connection width of the Ge absorption region 4603 and the P type lightly doped region 4604, or the connection width of the Ge absorption region 4603 and the N type lightly doped region 4601 is less than the connection width of the Ge absorption region 4603 and the P type lightly doped region 4604. In the embodiment of the present application, the width of the Ge absorption region 4603 is very small, which can be 1 micrometer.

[0073] When the optical signal transmitted by the coupling waveguide 450 enters the N type lightly doped region 4601 and the P type lightly doped region 4604 of the PN type doped region 460, the ionized particles in the N type lightly doped region 4601 and the P type lightly doped region 4604 move, and under the movement of the ionized particles in the N type lightly doped region 4601 and the P type lightly doped region 4604, the Ge absorption region 4603 absorbs the optical signal transmitted by the coupling waveguide 450, and a very strong electric field intensity is formed in the Ge absorption region 4603, and the functions of high modulation bandwidth and high optical responsivity are achieved.

[0074] In the embodiment of the present application, an N-type heavily doped region 4602 is disposed within the N-type lightly doped region 4601 of the PN-type doped region 460, and a P-type heavily doped region 4605 is disposed within the P-type lightly doped region 4604. Both the N-type heavily doped region 4602 and the P-type heavily doped region 4605 are located away from the Ge absorption region. Metal electrodes are also disposed on the silicon substrate 410. These metal electrodes include an N-region metal electrode and a P-region metal electrode. The N-region metal electrode contacts the N-type heavily doped region 4602, while the P-region metal electrode contacts the P-type heavily doped region 4605. Thus, electrical signals are transmitted through the N-region metal electrode and the P-region metal electrode.

[0075] Based on the optical module described in the above embodiment, an embodiment of the present application further provides a method for manufacturing a silicon photonic chip in an optical module. Figure 7 A method for manufacturing a silicon photonic chip is provided in an embodiment of the present application. Figure 8 This is a diagram of the manufacturing process structure of a silicon photonic chip provided in an embodiment of the present application. Figure 7 As shown, the method for manufacturing a silicon photonic chip provided in the embodiment of the present application includes:

[0076] S100: providing a silicon substrate.

[0077] like Figure 8 As shown, a silicon substrate 410 and a SiO2 layer 420 are arranged together as upper and lower layers, that is, the SiO2 layer 420 is placed on the upper layer of the silicon substrate 410. Specifically, SiO2 is deposited on the surface of the silicon substrate 410 to form the SiO2 layer 420; then, Si is deposited on the surface of the SiO2 layer 420 to form a silicon layer. The SiO2 layer 420 can be grown on the surface of the silicon substrate 410 using a low-temperature and high-temperature two-step chemical vapor deposition method, and a silicon layer can be grown on the surface of the SiO2 layer 420 using a chemical vapor deposition method to form a standard thickness SOI wafer. The specific thicknesses of the SiO2 layer 420 and the silicon layer can be selected by those skilled in the art according to actual needs.

[0078] S200: Fabricating an input waveguide on a silicon substrate.

[0079] The silicon layer is etched to form an input waveguide 440 , and the output end of the input waveguide 440 adopts a tapered adiabatic waveguide structure.

[0080] S300: fabricating an optical coupler at the input end of the input waveguide and a coupling waveguide at the output end.

[0081] After the input waveguide 440 is etched, the light coupler 430 and the coupling waveguide 450 are etched on the SiO2 layer 420 respectively. The coupling waveguide 450 has a strip waveguide at one end and a square waveguide at the other end, and is located on the SiO2 layer 420 under the input waveguide 440, so that the output end of the light coupler 430 is connected with the input end of the input waveguide 440, and the output end of the input waveguide 440 is connected with the input end of the coupling waveguide 450.

[0082] S400: P-type and N-type doped regions are made on the coupling waveguide.

[0083] N-type ions and P-type ions are respectively injected on both sides of the square waveguide region of the etched coupling waveguide 450 to form N-type lightly doped regions 4601, N-type heavily doped regions 4602, P-type lightly doped regions 4604 and P-type heavily doped regions 4605. The N-type heavily doped regions 4602 are formed in the N-type lightly doped regions 4601, the P-type heavily doped regions 4605 are formed in the P-type lightly doped regions 4604, and the N-type lightly doped regions 4601 and the P-type lightly doped regions 4604 can be connected to be centrally symmetrically distributed or can be spaced apart by a certain distance, as long as a PN structure can be formed.

[0084] S500: Ge absorption regions are made in the P-type and N-type doped regions.

[0085] The method of selective epitaxial growth can be used to grow Ge absorption regions 4603 on the N-type lightly doped regions 4601 and the P-type lightly doped regions 4604. The cross-sectional shape of the Ge absorption regions 4603 is a triangle or a trapezoid according to the crystal growth angle requirement, and the thickness and width of the Ge absorption regions 4603 can be set according to actual conditions.

[0086] S600: N-region metal electrodes and P-region metal electrodes are arranged on the silicon substrate, the N-region metal electrodes are in contact with the N-type doped regions, and the P-region metal electrodes are in contact with the P-type doped regions.

[0087] A first conductive material is deposited on the surface of the SiO2 layer 420 to form the N-region metal electrodes 470, which are in contact with the N-type heavily doped regions 4602. A second conductive material is deposited on the surface of the SiO2 layer 420 to form the P-region metal electrodes 480, which are in contact with the P-type heavily doped regions 4605, so as to realize electrical signal transmission.

[0088] Figure 9 Another manufacturing process structure diagram of a silicon optical chip is provided for the embodiments of the present application. As shown in Figure 9 The silicon optical chip provided by the embodiments of the present application can also be processed and manufactured by another manufacturing method. The manufacturing process is as follows:

[0089] SiO2 is deposited on the surface of the silicon substrate 410 by chemical vapor deposition to form a SiO2 layer 420, then Si is deposited on the surface of the SiO2 layer 420 by chemical vapor deposition to form a silicon layer, then the silicon layer and the SiO2 layer 420 are etched to form a coupling waveguide 450, one end of the coupling waveguide 450 is a strip waveguide and the other end is a square waveguide, then N-type ions and P-type ions are injected on both sides of the square waveguide region to form an N-type lightly doped region 4601, an N-type heavily doped region 4602, a P-type lightly doped region 4604 and a P-type heavily doped region 4605, the N-type heavily doped region 4602 is formed in the N-type lightly doped region 4601, the P-type heavily doped region 4605 is formed in the P-type lightly doped region 4604, and the N-type lightly doped region 4601 and the P-type lightly doped region 4604 can be connected to be centrally symmetrically distributed or can be spaced apart by a certain distance, as long as a PN structure can be formed, then a Ge absorption region 4603 can be grown on the N-type lightly doped region 4601 and the P-type lightly doped region 4604 by selective epitaxial growth, the cross-sectional shape of the Ge absorption region 4603 is a triangle or a trapezoid according to the crystal growth angle requirement, then an input waveguide 440 and an optical coupler 430 are etched on the silicon layer, the input end of the input waveguide 440 is connected to the output end of the optical coupler 430, the output end of the input waveguide 440 adopts a tapered adiabatic waveguide structure and is connected to the strip waveguide of the coupling waveguide 450, then a first conductive material is deposited on the surface of the SiO2 layer 420 to form an N-region metal electrode 470, the N-region metal electrode 470 is in contact with the N-type heavily doped region 4602, a second conductive material is deposited on the surface of the SiO2 layer 420 to form a P-region metal electrode 480, the P-region metal electrode 480 is in contact with the P-type heavily doped region 4605, so as to realize electrical signal transmission.

[0090] The optical module provided by the embodiment of the application is based on a silicon photon integrated platform, the input waveguide and the coupling waveguide are arranged above and below, and the Ge absorption region is arranged above the coupling waveguide with a small thickness, so that the thickness of the Ge absorption region can be reduced, the moving speed of electrons in the Ge absorption region is improved, the function of high modulation bandwidth is realized, in addition, the thickness of the coupling waveguide is small, so that the waveguide effective refractive index of the Ge absorption region is greater than the effective refractive index of the coupling waveguide, most of the optical field can be coupled into the Ge absorption region for detection and absorption, and therefore high optical responsivity can be realized. The special waveguide structure and the Ge detector design can realize high modulation bandwidth and high optical responsivity at the same time, and no additional complex process is needed.

[0091] Figure 10 Another structural diagram of a silicon optical chip 400 in an optical module provided by the embodiment of the application is shown in FIG. 4. Figure 10 As shown in the figure, in order to further increase the stability of the silicon optical chip 400, the device optical responsivity can be further improved by the double-end input mode of the Ge detector.

[0092] Specifically, the silicon photonic chip 400 is provided with an optical coupler 430, a first input waveguide 440, a first coupling waveguide 450, a second input waveguide 490, a second coupling waveguide 4110, a PN-type doped region 460, a Ge absorption region 4603 and a metal electrode. The optical coupler 430 is arranged on one side of the silicon substrate on the silicon photonic chip 400, and is used to couple the signal light transmitted by the optical fiber 101 to the silicon photonic chip 400.

[0093] The first input waveguide 440 and the second input waveguide 490 are symmetrically arranged on both sides of the optical coupler 430. That is, the optical coupler 430 has two output ends. The input end of the first input waveguide 440 is connected to one output end of the optical coupler 430, and the input end of the second input waveguide 490 is connected to the other output end of the optical coupler 430. In this way, the optical coupler 430 splits the received signal light into two, one beam of signal light is transmitted into the first input waveguide 440, and the other beam of signal light is transmitted into the second input waveguide 490.

[0094] The output end of the first input waveguide 440 adopts a tapered adiabatic waveguide structure and is connected to the input end of the first coupling waveguide 450, and the thickness of the first coupling waveguide 450 is less than the thickness of the first input waveguide 440; the output end of the second input waveguide 490 adopts a tapered adiabatic waveguide structure and is connected to the input end of the second coupling waveguide 4110, and the thickness of the second coupling waveguide 4110 is less than the thickness of the second input waveguide 490.

[0095] The thinner first coupling waveguide 450 and the second coupling waveguide 4110 share the same square waveguide area. The PN-type doped region 460 is placed on the square waveguide area. The PN-type doped region 460 includes an N-type lightly doped region 4601 and a P-type lightly doped region 4604. The N-type lightly doped region 4601 and the P-type lightly doped region 4604 are arranged in sequence along the direction of the light receiving optical path, and the P-type and N-type doped regions can be connected and distributed in a centrally symmetrical manner, or they can be separated by a certain distance, as long as a PN structure can be formed.

[0096] The Ge absorption region 4603 is arranged above the N-type lightly doped region 4601 and the P-type lightly doped region 4604, and the Ge absorption region 4603 is electrically connected with the N-type lightly doped region 4601 and the P-type lightly doped region 4604, respectively. The cross-sectional shape of the Ge absorption region 4603 is a triangle or a trapezoid according to the crystal growth angle requirement, and the width of the Ge absorption region 4603 is reduced, so that a very strong electric field strength can be formed inside the Ge absorption region 4603 under the N-type lightly doped region 4601 and the P-type lightly doped region 4604, the moving speed of the ion is improved, and a modulation bandwidth greater than 100 GHz is realized. In addition, due to the small thickness of the coupling waveguide 450, the effective refractive index of the Ge absorption region 4603 is greater than the effective refractive index of the coupling waveguide 450. Under the evanescent wave coupling, most of the optical field can be coupled into the Ge absorption region 4603 for detection and absorption, so that a very high optical responsivity can be realized.

[0097] The Ge detector in the silicon optical chip provided by the embodiment of the present application adopts a double-end input mode to detect and absorb the optical signal. Therefore, the optical signals transmitted by the first coupling waveguide 450 and the second coupling waveguide 4110 are all coupled into the Ge absorption region 4603 for detection and absorption, so that the optical responsivity of the optical module can be further improved.

[0098] Figure 11 A third structure diagram of the silicon optical chip 400 in the optical module is provided by the embodiment of the present application. As shown in the figure, Figure 11 the silicon optical chip 400 can also integrate a plurality of Ge detectors. The plurality of input waveguides are connected with the Ge detectors one by one, so that a multi-channel optical receiving optical path in the silicon optical chip 400 is realized, and high modulation bandwidth and high optical responsivity of multiple wavelengths are realized.

[0099] Specifically, the optical module provided by the embodiment of the present application includes a fiber array 500, which can include four optical fibers. The silicon optical chip 400 integrates four input waveguides 440 and four Ge detectors. One end of each optical fiber is connected with the input end of one input waveguide 440, and the output end of the input waveguide 440 is connected with one Ge detector. Therefore, the optical signal transmitted by each optical fiber is transmitted to the Ge detector through the input waveguide 440, and the optical signal is converted into an electrical signal by the Ge detector.

[0100] The silicon optical chip provided by the embodiment of the present application integrates a plurality of input waveguides and a plurality of Ge detectors, simultaneously realizes the reception of a plurality of different optical signals, and converts the plurality of different optical signals into a plurality of different electrical signals.

[0101] It has to be noted that, as used in this specification and claims, the terms "comprises", "comprising", "includes", "including", or the like are to be taken in their broadest possible sense and are not to be construed as limiting. In other words, it is intended that these terms be taken as encompassing the possession of the specified item or items, and the possibility of additional unspecified items being present.

[0102] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the content of the following claims.

[0103] The above-described embodiments of the application do not constitute a limitation in terms of the protection scope of the application.

Claims

1. An optical module, characterized in that: include: circuit boards; a silicon photonic chip, electrically connected to the circuit board, for receiving signal light transmitted by the optical fiber and performing electrical-to-optical conversion on the signal light; Wherein, the silicon photonic chip includes: Silicon substrate; an optical coupler, disposed on the silicon substrate, for coupling the signal light transmitted by the optical fiber to the silicon photonic chip; a first input waveguide, disposed on the silicon substrate, connected to a first output end of the optical coupler, and configured to transmit an optical signal received by the optical coupler; a first coupling waveguide, disposed below the first input waveguide, connected to the output end of the first input waveguide, having a thickness smaller than that of the first input waveguide and a width greater than that of the output end of the first input waveguide; the first coupling waveguide is configured to transmit the optical signal output by the first input waveguide; a second input waveguide, disposed on the silicon substrate, connected to the second output end of the optical coupler, and configured to transmit an optical signal received by the optical coupler; a second coupling waveguide, disposed below the second input waveguide, connected to the output end of the second input waveguide, having a thickness smaller than that of the second input waveguide and a width larger than that of the output end of the second input waveguide; the second coupling waveguide is configured to transmit the optical signal output by the second input waveguide; a PN-type doped region, disposed on the first coupling waveguide and the second coupling waveguide, the PN-type doped region being connected to the first coupling waveguide and the second coupling waveguide; the PN-type doped region comprising an N-type lightly doped region and a P-type lightly doped region, the N-type lightly doped region and the P-type lightly doped region extending along the direction of the light receiving optical path and being sequentially arranged along the width direction of the silicon photonic chip; an N-type heavily doped region being disposed within the N-type lightly doped region, and a P-type heavily doped region being disposed within the P-type lightly doped region; the PN-type doped region being used to receive optical signals transmitted by the first coupling waveguide and the second coupling waveguide; a Ge absorption region disposed above the N-type lightly doped region and the P-type lightly doped region to reduce the thickness of the Ge absorption region; the Ge absorption region is electrically connected to the N-type lightly doped region and the P-type lightly doped region, respectively; the N-type heavily doped region and the P-type heavily doped region are both away from the Ge absorption region; the waveguide effective refractive index of the Ge absorption region is greater than the effective refractive index of the first coupled waveguide and the second coupled waveguide; the Ge absorption region is used to absorb the transmitted optical signal and convert the optical signal into an electrical signal; A metal electrode is provided on the silicon substrate, the metal electrode including an N-region metal electrode and a P-region metal electrode, the N-region metal electrode contacts the N-type heavily doped region, and the P-region metal electrode contacts the P-type heavily doped region; the metal electrode is used to transmit the electrical signal.

2. The optical module according to claim 1, wherein The input end width of the first input waveguide is greater than the output end width of the first input waveguide, and the input end width of the second input waveguide is greater than the output end width of the second input waveguide.

3. The optical module according to claim 1, wherein: The thickness of the connection between the first input waveguide and the first coupling waveguide is the same as the thickness of the input end of the first input waveguide, and the thickness of the connection between the second input waveguide and the second coupling waveguide is the same as the thickness of the input end of the second input waveguide.

4. The optical module according to claim 1, wherein: The second input waveguide and the first input waveguide are symmetrically arranged on two sides of the optical coupler.

5. The optical module according to claim 1, wherein: The N-type lightly doped region is connected to the P-type lightly doped region, and the N-type lightly doped region and the P-type lightly doped region are centrally symmetrically distributed.

6. The optical module according to claim 1, wherein: There is a gap between the N-type lightly doped region and the P-type lightly doped region, and the N-type lightly doped region and the P-type lightly doped region form a PN structure.

7. The optical module according to claim 1, wherein: The connection width between the Ge absorption region and the N-type lightly doped region is the same as the connection width between the Ge absorption region and the P-type lightly doped region.

8. The optical module according to claim 1, wherein: The connection width between the Ge absorption region and the N-type lightly doped region is different from the connection width between the Ge absorption region and the P-type lightly doped region.

9. The optical module according to claim 1, wherein: The cross-section of the Ge absorption region is triangular or trapezoidal.

10. The optical module according to claim 1, wherein: The optical coupler is a grating coupler or an end face coupler.

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