CN111308621A - Optical module - Google Patents

Abstract

The application provides an optical module, includes: a circuit board; a light source for emitting light not carrying a signal; the optical waveguide coupler is arranged at an input port of the silicon optical chip, light which does not carry signals is coupled through the optical waveguide coupler, the light which does not carry signals is modulated into signal light, and the signal light is output through an output port of the silicon optical chip; the optical waveguide coupler includes: a substrate; a first silicon waveguide disposed on a substrate; the second silicon waveguide is arranged on the substrate and positioned on one side of the first silicon waveguide in the length direction, the length direction is parallel to the length direction of the first silicon waveguide, a space exists between the second silicon waveguide and the first silicon waveguide, cladding materials are filled in the space, and the thickness of the second silicon waveguide is larger than that of the first silicon waveguide; and the silicon nitride waveguide is arranged above the first silicon waveguide, has a distance with the first silicon waveguide, and is filled with a cladding material. The optical module provided by the application improves the coupling efficiency of light to the interior of a silicon optical chip through the optical waveguide coupler comprising the silicon nitride waveguide and the like.

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. In optical communication, an optical module is a tool for realizing the interconversion of optical signals and is one of the key devices in optical communication equipment. The silicon optical chip has the advantages of small size, high integration density and low cost, so that the silicon optical chip for realizing the electro-optic-photoelectric conversion function becomes a mainstream scheme adopted by the high-speed optical module.

However, in the use of the silicon optical chip to realize photoelectric conversion, it is found that when light generated by the laser enters the silicon optical chip through the light inlet of the silicon optical chip, the coupling efficiency from the signal light to the silicon optical chip is low due to the high refractive index of silicon. Meanwhile, the mode fields of the signal light in different polarization states are very different, so that the coupling efficiency of the signal light to the silicon optical chip is lower.

Disclosure of Invention

The embodiment of the application provides an optical module, which improves the coupling efficiency of signal light to a silicon optical chip.

In a first aspect, an optical module provided in an embodiment of the present application includes:

a circuit board;

the light source is electrically connected with the circuit board and is used for emitting light which does not carry signals;

the silicon optical chip is arranged on the circuit board and electrically connected with the circuit board, an input port of the silicon optical chip is provided with an optical waveguide coupler, the light which does not carry signals is received through the optical waveguide coupler in a coupling mode, the light which does not carry signals is modulated into signal light, and the signal light is output through an output port of the silicon optical chip;

the optical waveguide coupler includes:

a substrate;

a first silicon waveguide disposed on the substrate;

the second silicon waveguide is arranged on the substrate and positioned on one side of the first silicon waveguide in the length direction, the length direction is parallel to the length direction of the first silicon waveguide, a space exists between the second silicon waveguide and the first silicon waveguide, a cladding material is filled in the space, and the thickness of the second silicon waveguide is larger than that of the first silicon waveguide;

and the silicon nitride waveguide is arranged above the first silicon waveguide, has a space with the first silicon waveguide, and is filled with a cladding material.

In a second aspect, the present application provides a light module comprising:

a circuit board;

the optical waveguide coupler is arranged in an input port of the silicon optical chip, receives signal light transmitted to the optical waveguide coupler from the outside of the optical module through the optical waveguide coupler, modulates the signal light into an electric signal and outputs the electric signal through an optical port of the silicon optical chip;

the optical waveguide coupler includes:

a substrate;

a first silicon waveguide disposed on the substrate;

the second silicon waveguide is arranged on the substrate and positioned on one side of the first silicon waveguide in the length direction, the length direction is parallel to the length direction of the first silicon waveguide, a space is reserved between the second silicon waveguide and the first silicon waveguide, a cladding layer is filled in the space, and the thickness of the second silicon waveguide is larger than that of the first silicon waveguide;

and the silicon nitride waveguide is arranged above the first silicon waveguide, has a space with the first silicon waveguide, and is filled with a cladding layer in the space.

In the optical module provided by the application, light which is emitted by a light source and does not carry signals or signal light outside the optical module enters the input optical port of the silicon optical chip and enters the inside of the silicon optical chip through the optical waveguide coupler of the input optical port of the silicon optical chip in a coupling mode. The optical waveguide coupler includes a silicon nitride waveguide, a first silicon waveguide and a second silicon waveguide, the first silicon waveguide and the second silicon waveguide being disposed on a substrate, the silicon nitride waveguide being disposed above the first silicon waveguide. Light which does not carry signals enters an input port of the silicon optical chip and is coupled into the silicon nitride waveguide, and is gradually coupled into the first silicon waveguide in the transmission process of the silicon nitride waveguide. In the optical module provided by the application, because the refractive index of the silicon nitride waveguide is smaller than that of silicon, the coupling efficiency of light which is emitted by the light source and does not carry signals and passes through the silicon nitride waveguide is larger than that of the silicon waveguide, then the light which is coupled into the silicon nitride waveguide is coupled into the silicon optical chip by utilizing the first silicon waveguide which is relatively thin and the second silicon waveguide which is relatively thick, and the coupling efficiency of the light which is emitted by the light source and does not carry signals and enters the silicon optical chip is improved by fully utilizing the light waveguide coupling theory.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

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 according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of an exploded structure of an optical module according to an embodiment of the present application;

fig. 5 is a block diagram of an internal structure of an optical module according to an embodiment of the present disclosure;

fig. 6 is a front view of an optical waveguide coupler according to an embodiment of the present application;

fig. 7 is a top view of an optical waveguide coupler according to an embodiment of the present application;

FIG. 8 is a cross-sectional view taken along line A-A of FIG. 7;

FIG. 9 is a cross-sectional view taken along line B-B of FIG. 7;

FIG. 10 is a schematic diagram of a partition of a coupler provided in an embodiment of the present application;

fig. 11 is a schematic partial structure diagram of a first region of a coupler according to an embodiment of the present application;

FIG. 12 is a cross-sectional view taken along line C-C of FIG. 11;

fig. 13 is a schematic partial structural diagram of a second region of a coupler according to an embodiment of the present application;

FIG. 14 is a cross-sectional view taken in the direction D-D of FIG. 13;

fig. 15 is a schematic partial structural diagram of a third region of a coupler provided in an embodiment of the present application;

FIG. 16 is a cross-sectional view taken in the direction E-E of FIG. 15;

fig. 17 is a partial structural diagram of a fourth region of a coupler according to an embodiment of the present application;

FIG. 18 is a sectional view taken in the direction F-F in FIG. 17;

fig. 19 is a partial structural diagram of a fifth region of a coupler according to an embodiment of the present application;

fig. 20 is a sectional view taken in the direction of G-G in fig. 19.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

One of the core links of optical communication is the interconversion of optical and electrical signals. Optical communication uses optical signals carrying information to transmit in information transmission equipment such as optical fiber/optical waveguide, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of light in the optical fiber/optical waveguide; meanwhile, the information processing device such as a computer uses an electric signal, and in order to establish information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer, it is necessary to perform interconversion between the electric signal and the optical signal.

The optical module realizes the function of interconversion of optical signals and electrical signals in the technical field of optical communication, and the interconversion of optical signals and electrical 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 an internal circuit board of the optical module, and the main electrical connection comprises power supply, I2C signals, data signals, grounding and the like; the electrical connection mode realized by the gold finger has become the mainstream connection mode of the optical module industry, and on the basis of the mainstream connection mode, the definition of the pin on the gold finger forms various industry protocols/specifications.

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 the interconnection among the optical network terminal 100, the optical module 200, the optical fiber 101 and the network cable 103;

one end of the optical fiber 101 is connected with a far-end server, one end of the network cable 103 is connected with 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 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is made by the optical network terminal 100 having the optical module 200.

An optical port of the optical module 200 is externally accessed to the optical fiber 101, and establishes bidirectional optical signal connection with the optical fiber 101; an electrical port of the optical module 200 is externally connected to the optical network terminal 100, and establishes bidirectional electrical signal connection with the optical network terminal 100; the optical module realizes the interconversion of optical signals and electric signals, thereby realizing the establishment of 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 to 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 input to the optical fiber.

The optical network terminal is provided with an optical module interface 102, which is used for accessing an optical module 200 and establishing bidirectional electric signal connection with the optical module 200; the optical network terminal is provided with a network cable interface 104, which is used for accessing the network cable 103 and establishing bidirectional electric signal connection with the network cable 103; the optical module 200 is connected to the network cable 103 through the optical network terminal 100, specifically, the optical network terminal 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 terminal serves as an upper computer of the optical module to monitor the operation 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 terminal and the network cable.

Common information processing apparatuses include routers, switches, electronic computers, and the like; the optical network terminal 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 terminal structure. As shown in fig. 2, the optical network terminal 100 has 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 projection such as a fin that increases a heat radiation area.

The optical module 200 is inserted into the optical network terminal, 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 to the optical fiber 101.

The cage 106 is positioned on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged in the cage; the optical module is inserted into the cage, held by the cage, and the heat generated by the optical module is conducted to the cage 106 and then diffused by the heat sink 107 on the cage.

Fig. 3 is a schematic diagram of an optical module according to an embodiment of the present invention, and fig. 4 is a schematic diagram of an optical module according to an embodiment of the present invention. As shown in fig. 3 and 4, the optical module 200 according to the embodiment of the present invention includes an upper housing 201, a lower housing 202, an unlocking member 203, a circuit board 300, a silicon optical chip 400, a light source 500, and a fiber optic receptacle 600.

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 shell comprises a main plate and two side plates which are positioned at 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 realize that the upper shell covers 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 terminal; the other opening is an optical port 205 for external optical fiber access to connect with a silicon optical chip 403 inside the optical module; the photoelectric devices such as the circuit board 300, the silicon optical chip 400, the light source 500 and the like are positioned in the packaging cavity.

The assembly mode of combining the upper shell and the lower shell is adopted, so that the circuit board 300, the silicon optical chip 400 and other devices can be conveniently installed in the shells, and the upper shell and the lower shell form the outermost packaging protection shell of the optical module; the upper shell and the lower shell are made of metal materials generally, so that electromagnetic shielding and heat dissipation are facilitated; generally, the housing of the optical module is not made into an integrated component, so that when devices such as a circuit board and the like are assembled, the positioning component, the heat dissipation component and the electromagnetic shielding component cannot be installed, and the production automation is not facilitated.

The unlocking component 203 is located on the outer wall of the wrapping cavity/lower shell 202, and is 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 component 203 is provided with a clamping component matched with the upper computer cage; the end of the unlocking component can be pulled to enable the unlocking component 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 by a clamping component of the unlocking component; by pulling the unlocking component, the clamping component of the unlocking component moves along with the unlocking component, so that the connection relation between the clamping component and the upper computer is changed, the clamping relation between the optical module and the upper computer is released, and the optical module can be drawn out from the cage of the upper computer.

The circuit board 300 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as an MCU, a clock data recovery CDR, a power management chip, and a data processing chip DSP).

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

The circuit board is generally a hard circuit board, and the hard circuit board can also realize a bearing effect due to the relatively hard material of the hard circuit board, for example, the hard circuit board can stably bear a chip; when the optical transceiver is positioned on the circuit board, the rigid circuit board can also provide stable bearing; 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 silicon optical chip 400 is arranged on the circuit board 300 and electrically connected with the circuit board 300, and specifically can be wire bonding connection; the periphery of the silicon optical chip is connected to the circuit board 300 by a plurality of conductive wires, so the silicon optical chip 400 is generally disposed on the surface of the circuit board 300.

The silicon optical chip 400 is optically connected with the laser box 500 through the first optical fiber ribbon 401, and the silicon optical chip 400 receives light from the laser box 500 through the first optical fiber ribbon 401, so as to modulate the light, specifically, load a signal on the light; the silicon optical chip 400 receives light from the fiber optic receptacle 600, and converts the optical signal into an electrical signal.

The silicon optical chip 400 and the optical fiber receptacle 600 are optically connected through the second optical fiber ribbon 402, and the optical fiber receptacle 600 is optically connected to an optical fiber outside the optical module. The light modulated by the silicon optical chip 400 is transmitted to the optical fiber socket 600 through the second optical fiber ribbon 402 and transmitted to the external optical fiber through the optical fiber socket 600; light transmitted from the external optical fiber is transmitted to the optical fiber ribbon 401 through the optical fiber socket 600 and transmitted to the silicon optical chip 400 through the second optical fiber ribbon 402; therefore, the silicon optical chip 400 outputs light carrying data to the optical module external optical fiber or receives light carrying data from the optical module external optical fiber.

In the embodiment of the present application, the silicon optical chip 400 is provided with an input optical port, an output optical port, a monitoring optical port, a high-speed electrical signal interface, a dc bias signal interface, and the like. The input optical port comprises a first input optical port and a second input optical port, and the first input optical port is used for coupling the light output by the laser box 500 into the silicon optical chip; the second input port is used for coupling the light which carries data and is received by the external optical fiber of the optical module into the silicon optical chip; the output optical port is used to couple the modulated signal light out of the silicon optical chip 400.

The following description will be made in detail with reference to the optical waveguide coupler disposed in the first input optical port, taking as an example the improvement of the coupling efficiency of the light transmitted on the first optical fiber ribbon 401 into the silicon optical chip 400.

The silicon optical chip 400 is mainly made of silicon, and if the light output by the laser box 500 and transmitted through the first optical fiber ribbon 401 is directly coupled to the silicon core layer in the silicon optical chip 400 or coupled to the silicon core layer in the silicon optical chip 400 through the end-face coupler of the silicon waveguide structure, the coupling efficiency of the light into the silicon optical chip 400 is low because the refractive index of silicon is 3.5. In order to improve the coupling efficiency of light into the silicon optical chip 400, an optical waveguide coupler is disposed in the input optical port of the silicon optical chip 400, that is, the first input optical port and the second input optical port can both improve the coupling efficiency of response light by disposing the optical waveguide coupler.

Fig. 5 is a block diagram of an internal structure of an optical module according to an embodiment of the present application. As shown in fig. 5, an optical waveguide coupler 700 is disposed at an input port of the silicon optical chip 400 provided in the embodiment of the present application. In the present embodiment, the light output from the laser box 500 is transmitted through the first optical fiber ribbon 401, coupled to the optical waveguide coupler 700, and then coupled to the inside of the silicon optical chip 400 through the optical waveguide coupler 700.

In the optical waveguide coupler 700 provided in the embodiment of the present application, the optical waveguide includes a silicon nitride waveguide, a first silicon waveguide, and a second silicon waveguide, and a thickness of the first silicon waveguide is smaller than a thickness of the second silicon waveguide. Light output by the laser box 500 is transmitted to the end face of the optical waveguide coupler 700 through the first optical fiber ribbon 401, coupled to the silicon nitride waveguide 710, gradually coupled to the first silicon waveguide 720 through the silicon nitride waveguide 710, and coupled to the second silicon waveguide 730 through the first silicon waveguide 720, and the second silicon waveguide is connected with the silicon core layer in the silicon optical chip 400, so that the light is transmitted to the inside of the silicon optical chip 400 from the second silicon waveguide 730. Optical waveguide coupler 700 is used to achieve coupling of the light output by laser box 500 to silicon photonics chip 400.

Fig. 6 is a front view of an optical waveguide coupler 700 according to an embodiment of the present application, and as shown in fig. 6, the optical waveguide coupler 700 according to an embodiment of the present application includes a substrate, a cladding, a silicon nitride waveguide 710, a first silicon waveguide 720, and a second silicon waveguide 730. The first silicon waveguide 720 and the second silicon waveguide 730 are arranged on the substrate, the second silicon waveguide 730 is positioned on one side of the length direction of the first silicon waveguide, the length direction of the second silicon waveguide 730 is parallel to the length direction of the first silicon waveguide 720, and the thickness of the second silicon waveguide 730 is larger than that of the first silicon waveguide 720. The silicon nitride waveguide 710 is arranged above the first silicon waveguide 720, a space exists between the silicon nitride waveguide 710 and the first silicon waveguide 720, a cladding layer is filled in the space, and the length direction of the silicon nitride waveguide 710 is parallel to the length direction of the first silicon waveguide 720. Here, the "upper" is close to the upper portion with reference to the view direction of fig. 6.

Alternatively, a material having a refractive index smaller than that of the waveguide, such as silicon dioxide, is used as the substrate and the cladding of the silicon nitride waveguide 710, the first silicon waveguide 720, and the second silicon waveguide 730. In the present embodiment, the end faces of silicon nitride waveguides 710 are used to couple light transmitted thereto through first fiber optic ribbon 401.

Fig. 7 is a top view of an optical waveguide coupler 700 according to an embodiment of the present application, fig. 8 is a sectional view taken along a direction a-a in fig. 7, and fig. 9 is a sectional view taken along a direction B-B in fig. 7, which further illustrate a transmission path of light. As shown in fig. 7-9, the first silicon waveguide 720 is disposed above the silicon nitride waveguide 710, the second silicon waveguide 730 is disposed on a side of the first silicon waveguide 720 remote from the silicon nitride waveguide 710, and the second silicon waveguide 730 is spaced apart from the first silicon waveguide 720 with a cladding disposed therein. As can be seen in conjunction with fig. 6-9, the structure of the optical waveguide coupler 700 is a substrate and cladding wrapped silicon nitride waveguide 710, first silicon waveguide 720, and second silicon waveguide 730.

In the present embodiment, the silicon nitride waveguide 710 is a silicon nitride waveguide, and the first silicon waveguide 720 and the second silicon waveguide 730 are silicon waveguides. The refractive index of silicon is 3.5 and the refractive index of silicon nitride is 2, the refractive index of silicon nitride being less than the refractive index of silicon. When light output from the laser box 500 is transmitted to the end face of the optical waveguide coupler 700 through the first optical fiber ribbon 401 and coupled into the silicon nitride waveguide 710, since the silicon nitride waveguide 710 has a smaller refractive index than silicon, the coupling efficiency of coupling the light directly into the silicon core layer in the silicon optical chip 400 or coupling the light into the silicon core layer in the silicon optical chip 400 through the end face coupler of the silicon waveguide structure using the silicon nitride waveguide 710 is high, and then coupling the light into the silicon optical chip 400 through the first silicon waveguide 720 and the second silicon waveguide 730. Thus, light transmitted to silicon photonics chip 400 through first fiber optic ribbon 401 transitions through optical waveguide coupler 700, increasing the coupling efficiency of the light to silicon photonics chip 400.

In the embodiment of the present application, the optical waveguide coupler 700 has a relatively small size, and the upper surface can be up to 1mm². Optionally, the thickness of the silicon nitride waveguide 710 is less than 500nm, the thickness of the first silicon waveguide 720 is less than 200nm, and the thickness of the second silicon waveguide 730 is greater than 200 nm. For example, the silicon nitride waveguide 710 has a thickness of 250nm, the first silicon waveguide 720 has a thickness of 90nm, and the second silicon waveguide 730 has a thickness of 250 nm. The distance between the silicon nitride waveguide 710 and the first silicon waveguide 720 is 50nm-500nm, and the distance between the first silicon waveguide 720 and the second silicon waveguide 730 is 100nm-1000 nm. In this manner, the optical waveguide coupler 700 is facilitated to be downsized.

The embodiment of the present application provides the optical waveguide coupler 700, which is insensitive to the polarization state of light, and can be used for TE (perpendicular to the incident plane) polarized light and TM (parallel to the incident plane) polarized light, and can ensure that both TE and TM polarized light can be coupled into the silicon optical chip 400 with high coupling efficiency, and the optical coupling efficiency for TE and TM polarized light reaches more than 90%.

To facilitate the optical waveguide coupler 700 to achieve improved coupling efficiency of light into the silicon optical chip 400, the optical waveguide coupler 700 is divided along its length into a coupler first region, a coupler second region, a coupler third region, a coupler fourth region, and a coupler fifth region. Fig. 10 is a schematic diagram of a partitioned structure of an optical waveguide coupler 700 according to an embodiment of the present application. As shown in fig. 10, the first coupler region, the second coupler region, the third coupler region, the fourth coupler region, and the fifth coupler region are connected in this order.

In the embodiment of the present application, the silicon nitride waveguide 710 includes a first segment 711, a second segment 712, a third segment 713, a fourth segment 714, and a fifth segment 715, which are connected in sequence; the first silicon waveguide 720 includes a first section 721, a second section 722, a third section 723 and a fourth section 724 connected in sequence; the second silicon waveguide 730 includes a first segment 731, a second segment 732, and a third segment 733 connected in series. The length of each of the sections of the silicon nitride waveguide 710, the first silicon waveguide 720 and the second silicon waveguide 730 can be selected according to the actual requirements of the optical waveguide coupler 700 and the thickness of the silicon nitride waveguide 710, the first silicon waveguide 720 and the second silicon waveguide 730.

The following describes the optical waveguide coupler 700 provided in the embodiments of the present application in detail with reference to the partitions of the optical waveguide coupler 700.

Fig. 11 is a partial structural diagram of a first region of a coupler according to an embodiment, and fig. 12 is a sectional view taken along the direction C-C in fig. 11. As shown in fig. 11 and 12, the first region of the coupler includes a first segment 711 of a silicon nitride waveguide. Light output by the laser box 500 is transmitted to the end face of the optical waveguide coupler 700, that is, to the end face of the silicon nitride waveguide 710 through the first optical fiber ribbon 401, and is coupled to the first section 711 of the silicon nitride waveguide through the end face of the silicon nitride waveguide 710, light coupled to the first section 711 of the silicon nitride waveguide is independently and stably transmitted in the first section 711 of the silicon nitride waveguide, and the length and the width of the first section 711 of the silicon nitride waveguide satisfy a single-mode transmission condition.

Fig. 13 is a partial structural diagram of a second region of the coupler according to the embodiment, and fig. 14 is a sectional view taken along the direction D-D in fig. 13. As shown in fig. 13 and 14, the second region of the coupler comprises a second section 712 of the silicon nitride waveguide and a first section 721 of the first silicon waveguide, forming a hybrid waveguide system of silicon nitride and first silicon. Light propagating in the first segment 711 of the silicon nitride waveguide is gradually coupled into the hybrid waveguide system of silicon nitride and first silicon.

To reduce the coupling loss of the optical field from the silicon nitride waveguide to the hybrid waveguide system of silicon nitride and first silicon, the first section 721 of the first silicon waveguide has a width that gradually increases from its front end to its rear end. Alternatively, the width of the first section 721 of the first silicon waveguide is smallest at the front end thereof and gradually increases in the front-to-end direction thereof. In the drawing direction of fig. 10, the "front end" refers to the left end in fig. 10, and the "end" refers to the right end in fig. 10. Further, the front end of the first section 721 of the first silicon waveguide is the left end in fig. 13, and the end of the first section 721 of the first silicon waveguide is the right end in fig. 13. The width of the first section 721 of the first silicon waveguide is minimized at its front end to facilitate reducing coupling loss of the optical field from the silicon nitride waveguide to the silicon nitride-thin silicon hybrid waveguide system.

Further, the first section 721 of the first silicon waveguide is in an isosceles trapezoid shape, that is, the front end of the first section 721 of the first silicon waveguide has the minimum width of the first silicon waveguide 720, and both sides of the first section 721 of the first silicon waveguide are symmetrically and gradually increased along the length direction of the first silicon waveguide 720.

In addition, the width of the second segment 712 of the silicon nitride waveguide gradually decreases from the front end thereof to the end thereof. The second segment 712 of the silicon nitride waveguide is largest at its front end and tapers in the direction from its front end to its end. Optionally, the second section 712 of the silicon nitride waveguide is in an isosceles trapezoid shape, the front end of the second section 712 of the silicon nitride waveguide has the maximum width, and both sides of the second section 712 of the silicon nitride waveguide are symmetrically and gradually reduced along the length direction of the silicon nitride waveguide 710. Further, the end width of the second section 712 of the silicon nitride waveguide is equal to the end width of the first section 721 of the first silicon waveguide. In the embodiment of the present application, in order to couple the light transmitted by the first segment 711 of the silicon nitride waveguide into the hybrid waveguide system of silicon nitride and first silicon, the second segment 712 of the silicon nitride waveguide and the first segment 721 of the first silicon waveguide are kept long enough, which is selected according to the size of the actual optical waveguide coupler 700 and the thickness of the silicon nitride waveguide 710, the first silicon waveguide 720 and the second silicon waveguide 730.

Fig. 15 is a partial structural diagram of a third region of the coupler according to the embodiment, and fig. 16 is a sectional view taken along the direction E-E in fig. 15. As shown in fig. 15 and 16, the third section of the coupler comprises a third section 713 of a silicon nitride waveguide, a second section 722 of a first silicon waveguide, and a first section 731 of a second silicon waveguide, forming a hybrid waveguide system of silicon nitride, first silicon, and second silicon. Light propagating in the hybrid waveguide system of silicon nitride and first silicon is gradually coupled into the hybrid waveguide system of silicon nitride, first silicon and second silicon.

In the present embodiment, the first section 731 of the second silicon waveguide is gradually close to the mixed waveguide system of silicon nitride and first silicon, that is, the first section 731 of the second silicon waveguide is gradually close to the second section 722 of the first silicon waveguide, so as to ensure that the introduction of the second silicon waveguide does not cause the mode field change of the mixed waveguide system of silicon nitride and first silicon.

The front end of the first section 731 of the second silicon waveguide is spaced from the second section 722 of the first silicon waveguide by a distance of not less than 1 μm, and the end of the first section 731 of the second silicon waveguide is spaced from the second section 722 of the first silicon waveguide by a distance of 50nm to 500 nm.

In the embodiment of the present application, the light transmitted by the hybrid waveguide system of silicon nitride and the first silicon is almost completely coupled to the hybrid waveguide system of silicon nitride, the first silicon and the second silicon, and the third segment 713 of the silicon nitride waveguide, the second segment 722 of the first silicon waveguide and the first segment 731 of the second silicon waveguide are kept long enough, which is selected according to the size of the actual optical waveguide coupler 700 and the thickness of the silicon nitride waveguide 710, the first silicon waveguide 720 and the second silicon waveguide 730.

In the embodiment of the present application, optionally, the width of the first section 731 of the second silicon waveguide is gradually increased, and the first section 731 of the second silicon waveguide has a trapezoidal shape, that is, the front end of the first section 731 of the second silicon waveguide has the minimum width for the second silicon waveguide 730 to cancel. The first section 731 of the second silicon waveguide may have an isosceles trapezoid shape.

Fig. 17 is a partial structural diagram of a fourth region of the coupler according to the embodiment, and fig. 18 is a sectional view taken along a direction F-F in fig. 17. As shown in fig. 17 and 18, the fourth section of the coupler includes the fourth segment 714 of the silicon nitride waveguide, the third segment 723 of the first silicon waveguide, and the second segment 732 of the second silicon waveguide, continuing to form a hybrid waveguide system of silicon nitride, first silicon, and second silicon. The widths of the fourth segment 714 of the silicon nitride waveguide and the third segment 723 of the first silicon waveguide are gradually reduced from the front end to the tail end, and the width of the second segment 732 of the second silicon waveguide is gradually increased, so that light transmitted in a mixed waveguide system of silicon nitride, first silicon and second silicon is coupled to the second silicon waveguide 730. Meanwhile, the fourth section 714 of the silicon nitride waveguide, the third section 723 of the first silicon waveguide, and the second section 732 of the second silicon waveguide are kept long enough, which is selected according to the size of the actual optical waveguide coupler 700 and the thicknesses of the silicon nitride waveguide 710, the first silicon waveguide 720, and the second silicon waveguide 730.

The fourth segment 714 of the silicon nitride waveguide has a width that gradually decreases from its front end toward its end, and the third segment 723 of the first silicon waveguide has a width that gradually decreases from its front end toward its end. The fourth segment 714 of the silicon nitride waveguide has a decreasing width tendency equal to the decreasing width tendency of the third segment 723 of the first silicon waveguide. Optionally, the fourth segment 714 of the silicon nitride waveguide is in an isosceles trapezoid shape, the front end of the fourth segment 714 of the silicon nitride waveguide has the maximum width, and both sides of the fourth segment 714 of the silicon nitride waveguide are symmetrically and gradually reduced along the length direction of the silicon nitride waveguide 710; the third section 723 of the first silicon waveguide is in an isosceles trapezoid shape, the front end of the third section 723 of the first silicon waveguide has the largest width, and two sides of the third section 723 of the first silicon waveguide are symmetrically and gradually reduced along the length direction of the first silicon waveguide 720.

The second segment 732 of the second silicon waveguide gradually increases in width from the front end thereof to the end thereof. Optionally, the width of the second segment 732 of the second silicon waveguide is smallest at its front end and gradually increases in a front-to-end direction thereof. Further, the second section 732 of the second silicon waveguide is in an isosceles trapezoid shape, that is, the front end of the second section 732 of the second silicon waveguide has the minimum width of the second section 732 of the second silicon waveguide 720, and both sides of the second section 732 of the second silicon waveguide gradually increase along the length direction of the second silicon waveguide 720 in a symmetrical manner.

Fig. 19 is a partial structural diagram of a fifth region of the coupler according to the embodiment, and fig. 20 is a sectional view taken along the direction G-G in fig. 19. As shown in fig. 19 and 20, the fifth region of the coupler includes a fifth section 715 of a silicon nitride waveguide, a fourth section 724 of a first silicon waveguide, and a third section 733 of a second silicon waveguide, continuing to form a mixed waveguide system of silicon nitride, first silicon, and second silicon. In a mixed waveguide system of silicon nitride, first silicon and second silicon, the optical field is mainly distributed in the third section 733 of the second silicon waveguide. The fourth segment 724 of the first silicon waveguide is spaced from the third segment 733 of the second silicon waveguide by less than 500 nm.

The fifth section 715 of silicon nitride waveguide and the fourth section 724 of the first silicon waveguide ensure that light is coupled nearly completely into the third section 733 of the second silicon waveguide, and the lengths of the fifth section 715 of silicon nitride waveguide and the fourth section 724 of the first silicon waveguide can be arbitrarily selected. The third section 733 of the second silicon waveguide is used to connect a silicon core layer in the silicon optical chip 400, such as a single-mode silicon waveguide in the silicon optical chip 400, and the length of the third section 733 of the second silicon waveguide can be selected as required. For example, when the length required for connecting a single-mode silicon waveguide in the silicon optical chip 400 is long, the selected length is relatively long; when a shorter length is required to connect the single-mode silicon waveguides in silicon photonics chip 400, the length is selected to be relatively shorter. And when the third segment 733 of the second silicon waveguide is connected to the single-mode silicon waveguide in the silicon optical chip 400, the width of the third segment 733 of the second silicon waveguide is a preset width, and the selectable preset width is equal to the width of the single-mode silicon waveguide, so that light can be conveniently input into the single-mode waveguide through the third segment 733 of the second silicon waveguide.

In the embodiment of the present application, the coupling of light with different wavelengths to the silicon optical chip 400 with high coupling efficiency can be achieved by optimally adjusting the lengths of the respective segments of the silicon nitride waveguide 710, the first silicon waveguide 720 and the second silicon waveguide 730.

The optical waveguide coupler is arranged in the second input port and used for improving the coupling efficiency from the outside of the optical module to the silicon optical chip, and the optical waveguide coupler is similar to the optical waveguide coupler arranged in the first input port in the embodiment.

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

Claims (10)

1. A light module, comprising:

a circuit board;

the light source is electrically connected with the circuit board and is used for emitting light which does not carry signals;

the silicon optical chip is arranged on the circuit board and electrically connected with the circuit board, an input port of the silicon optical chip is provided with an optical waveguide coupler, the light which does not carry signals is received through the optical waveguide coupler in a coupling mode, the light which does not carry signals is modulated into signal light, and the signal light is output through an output port of the silicon optical chip;

the optical waveguide coupler includes:

a substrate;

a first silicon waveguide disposed on the substrate;

the second silicon waveguide is arranged on the substrate and positioned on one side of the first silicon waveguide in the length direction, the length direction is parallel to the length direction of the first silicon waveguide, a space exists between the second silicon waveguide and the first silicon waveguide, a cladding material is filled in the space, and the thickness of the second silicon waveguide is larger than that of the first silicon waveguide;

and the silicon nitride waveguide is arranged above the first silicon waveguide, a space exists between the silicon nitride waveguide and the first silicon waveguide, a cladding material is filled in the space, and the length direction of the silicon nitride waveguide is parallel to the length direction of the first silicon waveguide.

2. The optical module of claim 1, wherein the optical waveguide coupler is divided along its length into a first coupler region, a second coupler region, a third coupler region, and a fourth coupler region;

the silicon nitride waveguide comprises a first section, a second section, a third section and a fourth section which are connected in sequence, the first silicon waveguide comprises the first section, the second section and the third section which are connected in sequence, and the second silicon waveguide comprises the first section and the second section which are connected in sequence;

the first section of the silicon nitride waveguide is positioned in the first coupler region and is coupled to receive the light which does not carry signals;

the second section of the silicon nitride waveguide and the first section of the first silicon waveguide are positioned in the second region of the coupler, and the width of the first section of the first silicon waveguide is gradually increased from the front end to the tail end of the first section of the first silicon waveguide;

the third section of the silicon nitride waveguide, the second section of the first silicon waveguide and the first section of the second silicon waveguide are positioned in the third region of the coupler, and the first section of the second silicon waveguide is gradually close to the second section of the first silicon waveguide;

the fourth section of the silicon nitride waveguide, the third section of the first silicon waveguide and the second section of the second silicon waveguide are located in the fourth region of the coupler.

3. The optical module of claim 2, wherein the width of the second end of the silicon nitride waveguide gradually decreases from the front end to the end thereof.

4. The optical module of claim 2, wherein the width of the fourth section of the silicon nitride waveguide gradually decreases from the front end of the fourth section to the tail end of the fourth section, and the width of the third section of the first silicon waveguide gradually decreases from the front end of the third section to the rear end of the third section.

5. The optical module of claim 2, wherein the second segment of the second silicon waveguide has a width that gradually increases from a front end thereof to a tip end thereof.

6. The optical module of claim 2, wherein the second segment of the second silicon waveguide is parallel to the third segment of the first silicon waveguide.

7. The optical module of claim 2, wherein the optical waveguide coupler is further divided into a fifth coupler region along a length direction thereof, the fifth coupler region being located at an end of the fourth coupler region;

the end of the fourth section of the silicon nitride waveguide is connected with the fifth section of the silicon nitride waveguide; the end of the third section of the first silicon waveguide is connected with the fourth section of the first silicon waveguide; the tail end of the second section of the second silicon waveguide is connected with the third section of the second silicon waveguide;

the fifth section of the silicon nitride waveguide, the fourth section of the first silicon waveguide and the third section of the second silicon waveguide are located in the fifth region of the coupler.

8. The optical module of claim 2, wherein the third segment of the silicon nitride waveguide, the fourth segment of the silicon nitride waveguide, the second segment of the first silicon waveguide, and the third segment of the first silicon waveguide have equal widths.

9. The optical module of claim 2, wherein the thickness of the first silicon waveguide is less than 200nm, the thickness of the second silicon waveguide is greater than 200nm, the distance between the first silicon waveguide and the silicon nitride waveguide is 50-500nm, the distance between the front end of the first segment of the second silicon waveguide and the first silicon waveguide is greater than 1 μm, and the distance between the third segment of the first silicon waveguide and the second segment of the second waveguide is less than 500 nm.

10. A light module, comprising:

a circuit board;

the optical waveguide coupler is arranged in an input port of the silicon optical chip, receives signal light transmitted to the optical waveguide coupler from the outside of the optical module through the optical waveguide coupler, modulates the signal light into an electric signal and outputs the electric signal through an optical port of the silicon optical chip;

the optical waveguide coupler includes:

a substrate;

a first silicon waveguide disposed on the substrate;

the second silicon waveguide is arranged on the substrate and positioned on one side of the first silicon waveguide in the length direction, the length direction is parallel to the length direction of the first silicon waveguide, a space is reserved between the second silicon waveguide and the first silicon waveguide, a cladding layer is filled in the space, and the thickness of the second silicon waveguide is larger than that of the first silicon waveguide;

and the silicon nitride waveguide is arranged above the first silicon waveguide, has a space with the first silicon waveguide, and is filled with a cladding layer in the space.

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