WO2023093052A1

WO2023093052A1 - Optical module

Info

Publication number: WO2023093052A1
Application number: PCT/CN2022/102982
Authority: WO
Inventors: 梁海波; 章力明; 马军涛; 吴名忠
Original assignee: 青岛海信宽带多媒体技术有限公司
Priority date: 2021-11-29
Filing date: 2022-06-30
Publication date: 2023-06-01
Also published as: CN114156732A

Abstract

A laser chip and an optical module (200). The laser chip is integrated with a gain area, an optical grating area and an electro-absorption modulation area, wherein the gain area generates a light beam, and the optical grating area performs wavelength tuning on the light beam; a quantum well of the electro-absorption modulation area has a special structural design, thereby guaranteeing excellent transmission performance, and further improving the signal modulation speed; in addition, silicon dioxide layers are filled between a quantum well substrate layer and a metal electrode, between a reset layer and the metal electrode, and between a quantum well top layer and the metal electrode.

Description

optical module

This application claims the priority of the Chinese patent application with the application number 202111432015.1 and the title of the invention "a laser chip and optical module" submitted to the State Intellectual Property Office on November 29, 2021, the entire contents of which are incorporated herein by reference. Applying.

technical field

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

Background technique

In today's optical fiber transmission systems, the requirements for light sources are getting higher and higher. High-speed, high-integration, and wavelength-tunable light sources have always been a research hotspot in the industry, and laser chips integrated with electro-absorption modulators have emerged. There are technical problems in laser chips integrated with electro-absorption modulators: one , the signal modulation speed is basically at 10G, which cannot reach the high signal modulation speed of 25G, and thus cannot meet the transmission requirements of 10 kilometers. Simultaneous activation and maintenance.

Contents of the invention

A laser chip provided by an embodiment of the present disclosure includes: a gain region for generating light beams; a grating region for wavelength tuning the light beams from the gain region; an electroabsorption modulation region including quantum wells, the quantum The well includes a quantum well substrate layer, a first heterojunction layer, a potential well and barrier layer, a second heterojunction layer, a back-up layer and a quantum well top layer stacked on each other, wherein the quantum well substrate layer and the metal electrode A silicon dioxide layer is filled between the gap, between the reset layer and the metal electrode, and between the top layer of the quantum well and the metal electrode, and is used for signal modulation of the light beam from the grating area.

Description of drawings

In order to illustrate the technical solutions in the present disclosure more clearly, the following will briefly introduce the accompanying drawings required in some embodiments of the present disclosure. Obviously, the accompanying drawings in the following description are only appendices to some embodiments of the present disclosure. Figures, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limitations on the actual size of the product involved in the embodiments of the present disclosure, the actual process of the method, the actual timing of signals, and the like.

Fig. 1 is a connection diagram of an optical communication system according to some embodiments;

Fig. 2 is a structural diagram of an optical network terminal according to some embodiments;

Fig. 3 is a structural diagram of an optical module according to some embodiments;

Figure 4 is an exploded view of an optical module according to some embodiments;

5 is a schematic diagram of the appearance of a laser chip according to some embodiments;

6 is a schematic diagram of an outer edge growth structure of a laser chip according to some embodiments;

7 is a schematic diagram of a quantum well structure in an electroabsorption modulation region in a laser chip according to some embodiments;

Fig. 8 is a schematic diagram of a modulation speed of a laser chip according to some embodiments;

Fig. 9 is a schematic diagram of the variation of the wavelength of a laser chip with the injection current according to some embodiments;

Fig. 10 is a schematic diagram of a manufacturing process of a laser chip according to some embodiments.

Detailed ways

The technical solutions in some embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only some of the embodiments of the present disclosure, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments provided in the present disclosure belong to the protection scope of the present disclosure.

Throughout the specification and claims, unless the context requires otherwise, the term "comprise" and other forms such as the third person singular "comprises" and the present participle "comprising" are used Interpreted as the meaning of openness and inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific examples" example)" or "some examples (some examples)" etc. are intended to indicate that specific features, structures, materials or characteristics related to the embodiment or examples are included in at least one embodiment or example of the present disclosure. Schematic representations of the above terms are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

Hereinafter, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

In describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more elements are in direct physical or electrical contact with each other. As another example, the term "coupled" may be used when describing some embodiments to indicate that two or more elements are in direct physical or electrical contact. However, the terms "coupled" or "communicatively coupled" may also mean that two or more elements are not in direct contact with each other, but yet still co-operate or interact with each other. The embodiments disclosed herein are not necessarily limited by the context herein.

"At least one of A, B and C" has the same meaning as "at least one of A, B or C" and both include the following combinations of A, B and C: A only, B only, C only, A and B A combination of A and C, a combination of B and C, and a combination of A, B and C.

"A and/or B" includes the following three combinations: A only, B only, and a combination of A and B.

The use of "configured to" herein means open and inclusive language that does not exclude devices configured to perform additional tasks or steps.

As used herein, "about", "approximately" or "approximately" includes the stated value as well as the average within the acceptable deviation range of the specified value, wherein the acceptable deviation range is as determined by one of ordinary skill in the art. Determined taking into account the measurement in question and the errors associated with the measurement of a particular quantity (ie, limitations of the measurement system).

In optical communication technology, light is used to carry information to be transmitted, and the optical signal carrying information is transmitted to information processing equipment such as a computer through optical fiber or optical waveguide and other information transmission equipment to complete the information transmission. Because optical signals have passive transmission characteristics when they are transmitted through optical fibers or optical waveguides, low-cost, low-loss information transmission can be achieved. In addition, the signals transmitted by information transmission equipment such as optical fibers or optical waveguides are optical signals, while the signals that can be recognized and processed by information processing equipment such as computers are electrical signals. To establish an information connection between them, it is necessary to realize the mutual conversion of electrical signals and optical signals.

The optical module realizes the mutual conversion function of the above-mentioned optical signal and electrical signal in the technical field of optical fiber communication. The optical module includes an optical port and an electrical port. The optical module realizes optical communication with information transmission equipment such as optical fiber or optical waveguide through the optical port, and realizes the electrical connection with the optical network terminal (such as an optical modem) through the electrical port. It is mainly configured to implement power supply, I2C signal transmission, data signal transmission, and grounding. Optical network terminals transmit electrical signals to information processing equipment such as computers through network cables or wireless fidelity technology (Wi-Fi).

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

One end of the optical fiber 101 is connected to the remote server 1000 , and the other end is connected to the optical network terminal 100 through the optical module 200 . Optical fiber itself can support long-distance signal transmission, such as signal transmission of several kilometers (6 kilometers to 8 kilometers). On this basis, if repeaters are used, ultra-long-distance transmission can theoretically be achieved. Therefore, in a common optical communication system, the distance between the remote server 1000 and the optical network terminal 100 can usually reach thousands of kilometers, tens of kilometers or hundreds of kilometers.

One end of the network cable 103 is connected to the local information processing device 2000 , and the other end is connected to the optical network terminal 100 . The local information processing device 2000 may be any one or more of the following devices: routers, switches, computers, mobile phones, tablet computers, televisions, and so on.

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

The optical module 200 includes an optical port and an electrical port. The optical port is configured to be connected to the optical fiber 101 , so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101 . The electrical port is configured to be connected to the optical network terminal 100 , so that the optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100 . The optical module 200 implements mutual conversion between optical signals and electrical signals, so that a connection is established between the optical fiber 101 and the optical network terminal 100 . For example, the optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input to the optical network terminal 100 , and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input to the optical fiber 101 .

The optical network terminal 100 includes a substantially rectangular parallelepiped housing (housing), and an optical module interface 102 and a network cable interface 104 disposed on the housing. The optical module interface 102 is configured to be connected to the optical module 200 , so that the optical network terminal 100 establishes a bidirectional electrical signal connection with the optical module 200 . The network cable interface 104 is configured to access the network cable 103 , so that the optical network terminal 100 establishes a bidirectional electrical signal connection with the network cable 103 . A connection is established between the optical module 200 and the network cable 103 through the optical network terminal 100 . For example, the optical network terminal 100 transmits the electrical signal from the optical module 200 to the network cable 103, and transmits the signal from the network cable 103 to the optical module 200. Therefore, the optical network terminal 100, as the host computer of the optical module 200, can monitor the optical module 200 work. In addition to the optical network terminal 100, the host computer of the optical module 200 may also include an optical line terminal (Optical Line Terminal, OLT) and the like.

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

FIG. 2 is a structural diagram of an optical network terminal according to some embodiments. In order to clearly show the connection relationship between the optical module 200 and the optical network terminal 100, FIG. 2 only shows the optical network terminal 100 related to the optical module 200. structure. As shown in FIG. 2 , the optical network terminal 100 further includes a PCB circuit board 105 disposed in the casing, a cage 106 disposed on the surface of the PCB circuit board 105 , and an electrical connector disposed inside the cage 106 . The electrical connector is configured to be connected to an electrical port of the optical module 200 . A radiator 107 is provided on the cage 106, and the radiator 107 has protrusions such as fins that increase the heat dissipation area.

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

Fig. 3 is a structural diagram of an optical module according to some embodiments, and Fig. 4 is an exploded view of an optical module according to some embodiments. As shown in FIG. 3 and FIG. 4 , the optical module 200 includes a housing, a circuit board 105 disposed in the housing, and an optical transceiver device.

The casing includes an upper casing 201 and a lower casing 202. The upper casing 201 covers the lower casing 202 to form the above casing with two

openings

204 and 205. The outer contour of the casing generally presents a square shape.

In some embodiments of the present disclosure, the lower housing 202 includes a bottom plate and two lower side plates located on both sides of the bottom plate and perpendicular to the bottom plate. The upper case 201 includes a cover plate, and two upper side plates perpendicular to the cover plate on both sides of the cover plate, and the two side walls are combined with the two side plates to realize that the upper case 201 is covered by the lower case 202 superior.

The direction of the line connecting the two

openings

204 and 205 may be consistent with the length direction of the optical module 200 , or may not be consistent with the length direction of the optical module 200 . For example, the opening 204 is located at the end of the optical module 200 (the left end in FIG. 3 ), and the opening 205 is also located at the end of the optical module 200 (the right end in FIG. 3 ). Alternatively, the opening 204 is located at the end of the optical module 200 , while the opening 205 is located at the side of the optical module 200 . Wherein, the opening 204 is an electrical port, and the golden finger of the circuit board 105 protrudes from the electrical port 204 and is inserted into a host computer (such as the optical network terminal 100 ). The opening 205 is an optical port configured to be connected to an external optical fiber 101 so that the optical fiber 101 is connected to an optical transceiver device inside the optical module 200 .

The combination of the upper case 201 and the lower case 202 is used to facilitate the installation of components such as the circuit board 105 into the case, and the upper case 201 and the lower case 202 can form package protection for these devices. In addition, when assembling components such as the circuit board 105 , it is convenient to deploy positioning components, heat dissipation components and electromagnetic shielding components of these components, which is conducive to automatic implementation of production.

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

In some embodiments, the optical module 200 further includes an unlocking part 203 located on the outer wall of its housing, and the unlocking part 203 is configured to realize a fixed connection between the optical module 200 and the host computer, or release the connection between the optical module 200 and the host computer. fixed connection.

Exemplarily, the unlocking component 203 is located on the outer walls of the two lower side panels of the lower housing 202 , and includes an engaging component matching with a cage of the upper computer (for example, the cage 106 of the optical network terminal 100 ). When the optical module 200 is inserted into the cage of the host computer, the optical module 200 is fixed in the cage of the host computer by the engaging part of the unlocking part 203; when the unlocking part 203 is pulled, the engaging part of the unlocking part 203 moves accordingly, thereby changing The connection relationship between the engaging part and the host computer is to release the engagement relationship between the optical module 200 and the host computer, so that the optical module 200 can be pulled out from the cage of the host computer.

The circuit board 105 includes circuit traces, electronic components and chips, through which the electronic components and chips are connected together according to the circuit design, so as to realize functions such as power supply, electrical signal transmission and grounding. The electronic components may include, for example, capacitors, resistors, transistors, and metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). Chips can include, for example, a Microcontroller Unit (MCU), a limiting amplifier (limiting amplifier), a clock data recovery chip (Clock and Data Recovery, CDR), a power management chip, and a digital signal processing (Digital Signal Processing, DSP) chip. .

The circuit board 105 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also realize the carrying function, for example, the rigid circuit board can carry chips stably. The rigid circuit board also plugs into electrical connectors in the host computer cage.

The circuit board 105 also includes gold fingers formed on the surface of its end, and the gold fingers are composed of a plurality of independent pins. The circuit board 105 is inserted into the cage 106 and electrically connected with the electrical connector in the cage 106 by the gold fingers. Gold fingers can be arranged only on one side of the circuit board 105 (for example, the upper surface shown in FIG. 4 ), or on the upper and lower sides of the circuit board 105, so as to meet the occasions where the number of pins is large. The golden finger is configured to establish an electrical connection with the host computer to realize power supply, grounding, I2C signal transmission, data signal transmission, etc. Of course, flexible circuit boards are also used in some optical modules. Flexible circuit boards are generally used in conjunction with rigid circuit boards as a supplement to rigid circuit boards.

The optical module of the silicon photonics structure further includes a silicon photonics chip 400 , the silicon photonics chip 400 has no light source itself, and the light source assembly 500 is used as an external light source of the silicon photonics chip 400 . The light source assembly 500 can be a laser box, and a laser chip is packaged inside the laser box. The laser chip emits light to generate a laser beam. With better single-wavelength characteristics and better wavelength tuning characteristics, laser has become the preferred light source for optical modules and even optical fiber transmission, while other types of light, such as LED light, are generally not used in common optical communication systems, even if special optical communication This kind of light source is used in the system, the characteristics of the light source and the chip components are quite different from the laser, so that there is a big technical difference between the optical module using the laser and the optical module using other light sources. Generally, those skilled in the art will not It is believed that these two types of optical modules can give technical inspiration to each other.

The bottom surface of the silicon photonics chip 400 and the bottom surface of the light source assembly 500 are respectively arranged on the substrate. There is an optical connection between the silicon photonics chip and the light source. The optical path is very sensitive to the positional relationship between the silicon photonics chip and the light source. Materials with different expansion coefficients It will cause different degrees of deformation, which is not conducive to the realization of the preset optical path. In the embodiment of the present disclosure, the silicon photonic chip and the light source are arranged on the same substrate, and the deformation of the substrate of the same material will equally affect the position of the silicon photonic chip and the light source, avoiding the relative position of the silicon photonic chip and the light source. produce larger changes. It is preferable to make the expansion coefficient of the substrate material close to that of the silicon photonics chip and/or the material of the light source. The main material of the silicon photonics chip is silicon, the light source can be made of Kovar metal, and the substrate is generally made of silicon or glass.

There are many kinds of relationships between the substrate and the circuit board 105, one of which is shown in Figure 4, the circuit board 105 has an opening through the upper and lower surfaces, and the silicon photonic chip and/or light source are arranged in the opening, so that the silicon photonic chip and /or the light source can dissipate heat to the upper surface of the circuit board and the lower surface of the circuit board at the same time, the substrate is arranged on one side of the circuit board, the silicon photonic chip and/or the light source pass through the opening of the circuit board and then placed on the heat dissipation substrate, The substrate plays the role of support and heat dissipation. In another way, the circuit board is not provided with openings, and the substrate is provided on the circuit board. The substrate may be provided on the surface of the circuit board or embedded in the circuit board, and the silicon photonics chip and the light source are provided on the surface of the substrate.

The bottom surface of the light source assembly 500 is disposed on the substrate, the light source assembly 500 emits light through the side, and the emitted light enters the silicon photonics chip 400 . The silicon photonics chip uses silicon as the main substrate, and silicon is not an ideal light-emitting material. The silicon photonics chip 400 cannot integrate a light source, and an external light source module 500 is required to provide the light source. The light provided by the light source assembly 500 to the silicon photonics chip is emitted light with a single wavelength and stable power without carrying any data. The emitted light is modulated by the silicon photonics chip 400 to load data into the emitted light.

The bottom surface of the silicon photonics chip 400 is set on the substrate, the side of the silicon photonics chip 400 receives the emitted light from the light source, and the modulation of the emitted light and the demodulation of the received light are completed by the silicon photonics chip. The surface of the silicon photonics chip is provided with pads that are electrically connected to the circuit board by wire bonding. In some embodiments of the present disclosure, the circuit board provides the silicon photonic chip with the data signal from the upper computer, and the silicon photonic chip modulates the data signal into the emitted light, and the received light from the outside is demodulated into an electrical signal by the silicon photonic chip After that, it is output to the host computer through the circuit board.

Both the first optical fiber ribbon 600 and the second optical fiber ribbon 700 are formed by merging multiple optical fibers. In the embodiment of the present disclosure, the first optical fiber ribbon 600 is a transmitting optical fiber ribbon, and the second optical fiber ribbon 700 is a receiving optical fiber ribbon. One end of the first optical fiber ribbon 600 is connected to the silicon photonics chip 400 , and the other end is connected to the optical fiber interface 800 ; one end of the second optical fiber ribbon 700 is connected to the silicon photonics chip 400 , and the other end is connected to the optical fiber interface 800 . The optical fiber interface 800 is connected with an external optical fiber. It can be seen that the optical connection between the silicon photonics chip 400 and the optical fiber interface 800 is realized through the first optical fiber ribbon 600 and the second optical fiber ribbon 700, and the optical fiber interface 800 realizes the optical connection with the external optical fiber of the optical module.

The light source assembly 500 transmits the emitted light that does not carry a signal to the silicon photonic chip 400, and the silicon photonic chip 400 modulates the emitted light that does not carry a signal, loads data into the emitted light that does not carry a signal, and then converts the emitted light that does not carry a signal The transmitted light is modulated into transmitted light carrying a data signal. The emitted light carrying the data signal is transmitted to the optical fiber interface 800 through the first optical fiber ribbon 600, and then transmitted to the external optical fiber through the optical fiber interface 800, so that the light carrying the data signal is transmitted to the external optical fiber of the optical module to realize the conversion of the electrical signal for the light signal.

The optical signal from the external optical fiber is transmitted to the optical fiber interface 800, and then the optical signal is transmitted to the silicon optical chip 400 through the second optical fiber ribbon 700, and the silicon optical chip 400 demodulates the optical signal into an electrical signal and outputs it through the circuit board In the upper computer, the optical signal is converted into an electrical signal.

The light source assembly 500 in the embodiment of the present disclosure includes a laser chip, and the surface of the laser chip in the embodiment of the present disclosure is integrated with a gain region, a grating region and an electroabsorption modulation region. The gain region generates photons and is amplified, the grating region selects the frequency of the amplified light wave, and the electroabsorption modulation region modulates a specific wavelength, and then realizes the output of laser light with a specific wavelength. By changing the magnitude of the current injected into the grating area, the refractive index of the waveguide in the grating area can be continuously changed, thereby outputting beams of different wavelengths. The length of the electroabsorption modulation region is designed to be long, and a sufficiently long electroabsorption modulation region can ensure sufficient electroabsorption capacity, ensure that the device response speed is fast enough, and increase the signal modulation speed, and the quantum well in the electroabsorption modulation region has a special structural design, Ensure excellent transmission performance and further improve signal modulation speed. At the same time, between the quantum well substrate layer and the metal electrode, between the reset layer and the metal electrode, between the quantum well top layer and the metal electrode, are filled with a silicon dioxide layer, and the setting of the silicon dioxide layer can adjust the chip capacitance to obtain a smaller The parasitic capacitance further improves the signal modulation speed. The electro-absorption modulation area in the embodiments of the present disclosure is specially designed to achieve a 25G signal modulation speed and meet the transmission distance requirement of 10 kilometers. Therefore, the laser chip in the embodiment of the present disclosure is a chip with integrated gain, adjustable wavelength, and electrical signal modulation functions, which is of great significance to optical fiber transmission systems.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

FIG. 5 is a schematic diagram of the appearance of a laser chip according to some embodiments; FIG. 6 is a schematic diagram of an outer edge growth structure of a laser chip according to some embodiments.

As shown in Figure 5, the surface of the laser chip in the embodiment of the present disclosure includes a gain region, a grating region, and an electroabsorption modulation region. between. The gain region generates photons and is amplified, the grating region selects the frequency of the amplified light wave, and the electroabsorption modulation region modulates a specific wavelength, and then realizes the output of laser light with a specific wavelength. The electroabsorption modulation region can change the magnitude of its own light absorption loss, thereby realizing the modulation of the optical signal. The electroabsorption modulation region includes a quantum well structure, and the quantum well structure is formed by stacking layers of materials with different forbidden band widths.

A first isolation area is provided between the gain area and the grating area, and a second isolation area is provided between the grating area and the electroabsorption modulation area. As shown in Figure 5, the length of the gain region is 375 μm, the length of the grating region is 150 μm, the length of the electroabsorption modulation region is 110 μm, the length of the first isolation region is 45 μm, and the length of the second isolation region is 80 μm.

As shown in Figure 6, the gain region includes an InP cushion layer, a waveguide layer, a gain quantum well structure layer, and a p-type doped InP layer stacked from bottom to top, respectively corresponding to the n-InP substrate in the gain region on the left side of Figure 6 , buffer layers layer, waveguide layer, Gain MQW/SCH layers layer, P-InP clad layer.

The grating area includes an InP cushion layer, a grating layer and a waveguide layer stacked from bottom to top, corresponding to the n-InP substrate, buffer layers, Grating layer and waveguide layer in the grating area in the middle of Figure 6, respectively.

The electroabsorption modulation area includes InP cushion layers and electroabsorption modulation quantum well structure layers stacked from bottom to top, corresponding to the n-InP substrate, buffer layers and Gain MQW/SCH layers of the electroabsorption modulation area on the right side of Figure 6 .

In the embodiments of the present disclosure, for convenience of description, the first layer, the second layer, etc. are defined in a direction from top to bottom. The first layer, the second layer, the third layer and the fourth layer of the gain area are p-type doped InP layer, gain quantum well structure layer, waveguide layer and InP cushion layer respectively; the first layer and the second layer of the grating area empty, the third layer is the waveguide layer, the fourth layer is the grating layer, and the fifth layer is the InP pad layer; the first and second layers of the electroabsorption modulation area are empty, and the third and fourth layers are electroabsorption The quantum well structure layer is modulated, and the fifth layer is an InP cushion layer. It can be seen that the first layer and the second layer corresponding to the grating area and the electroabsorption modulation area are blank, that is, the first layer and the second layer of the gain area are blank to the right. In Figure 6, the gain area is on the left side, and the electrical The absorption modulation region is on the right. It can be seen that, in the embodiments of the present disclosure, an innovative lateral coupling process is used for the gain region and the grating region instead of the traditional tailing growth process, thereby reducing the need for an outer edge growth.

The light generated from the quantum well in the gain region will finally flow laterally into the waveguide layer for wavelength selection in the grating region.

The embodiments of the present disclosure provide a lateral coupling technology, which reduces the loss from the gain region to the wavelength adjustment region, and simultaneously simplifies the process flow.

In the embodiment of the present disclosure, the grating region includes a grating layer and a waveguide layer. The grating layer (marked with grating material in the figure) is an InGaAsP material with a photoluminescence peak of 1250 nm and a thickness of 300A (1A is ten minus ten meters). The waveguide layer is InGaAsP material with a photoluminescence peak of 1380nm, the thickness is 2900A, and the waveguide layer is lightly doped 2X1017/cm3. The setting of the material thickness in the embodiment of the present disclosure needs to meet the requirements of the wavelength modulation range and the light propagation loss is small.

By changing the magnitude of the current injected into the grating area to output light beams of different wavelengths, the grating in the embodiment of the present disclosure is a distributed Bragg reflection grating, and the entire light source chip is only exposed to a holographic pattern once to form the grating, so the period of the grating is fixed. By changing the magnitude of the current injected into the grating area, the waveguide refractive index in the grating area can be continuously changed, thereby realizing the continuous change of the grating passband, and selecting the Fabry-Perot mode corresponding to the target wavelength.

Compared with mechanical tuning and thermal tuning for wavelength adjustment, electrical tuning for wavelength adjustment has a larger wavelength adjustment range and faster wavelength switching speed, which can better meet the needs of optical fiber communication for lasers. Electrical tuning is achieved by injecting carriers into the grating region to change the refractive index of its material.

Fig. 9 is a schematic diagram of a laser chip wavelength changing with injection current according to some embodiments, wherein the abscissa DBR current represents the laser chip injection current, and the ordinate Wavelength represents the laser chip wavelength. As shown in FIG. 9 , the laser chip in the embodiment of the present disclosure can achieve a wavelength change of about 11 nm when the injection current is 50 mA, which can cover the requirement of 8 nm wavelength change with a margin.

In summary, in the laser chip of the embodiment of the present disclosure, by changing the magnitude of the current injected into the grating region, the refractive index of the waveguide in the grating region can be continuously changed, thereby outputting beams of different wavelengths.

In the embodiment of the disclosure, in order to enable the laser chip to achieve an electrical modulation rate of 25 GHz and meet the requirement of a transmission distance of 10 kilometers, the embodiment of the disclosure has the following special structure for the electro-absorption modulation region:

In some embodiments, the material of the electron trap structure in the electroabsorption modulation region is determined by the overall photoluminescence peak position of the electroabsorption region. After repeated tests, the value is the target wavelength minus 60nm, and only when it is near the design value , Transmission performance optimization. Fig. 7 is a schematic diagram of a quantum well structure of an electroabsorption modulation region in a laser chip according to some embodiments. As shown in Figure 7, the quantum well comprises a relatively stacked quantum well substrate layer, a first heterojunction layer, a potential well and a barrier layer, a second heterojunction layer, a reset layer and a quantum well top layer, wherein the quantum well A silicon dioxide layer is filled between the well substrate layer and the metal electrode, between the reset layer and the metal electrode, and between the quantum well top layer and the metal electrode. The parameters of each layer are as follows:

The quantum well substrate layer is an n-type InP substrate, above which is the first heterojunction layer, and the material is InGaAsP material with a photoluminescence peak of 1170nm, and the thickness is 420A (1A is ten minus ten meters). On top are 8 groups of potential wells and 8 groups of potential barriers, wherein the potential well regions have a compression amount of 0.6-0.8%, and the potential barrier regions have a relaxation amount of 0.2-0.4%. In one embodiment, the thickness of the 8 groups of potential wells is 90A, and the design requires a compression of 0.7% in the potential well region; the thickness of the 8 groups of potential barriers is 50A, and the material is InGaAsP material with a photoluminescence peak of 1170nm. A relaxation of 0.3% in the barrier region is required. Above that is a second heterojunction layer with the same parameters as the first heterojunction layer. On top of that is a layer of 800A InP repositioning layer, which is used to dilute the doping inflow from the upper layer. The top is p-type InP material.

In some embodiments, the length of the electroabsorption modulation region is 110um, and a sufficiently long length of the electroabsorption modulation region can ensure sufficient electroabsorption capacity, so that the extinction ratio of the device meets the application requirements; a sufficiently long length of the electroabsorption modulation region can obtain a higher Small capacitance, small time parameters, thereby improving the response speed of the device.

In some embodiments, a silicon dioxide layer is filled between the quantum well substrate layer and the metal electrode, between the reset layer and the metal electrode, and between the quantum well top layer and the metal electrode. The material of the quantum well substrate layer, the reset layer and the quantum well top layer are all InP materials, between the chip InP material and the metal electrode, filling thicker silicon dioxide material can adjust the chip capacitance. In the embodiment of the present disclosure, the silicon dioxide layer is made of 5000A thick silicon dioxide, so as to obtain smaller parasitic capacitance and improve device speed. FIG. 8 is a schematic diagram of a modulation speed of a laser chip according to some embodiments. As shown in FIG. 8 , the 3dB bandwidth of S21 exceeds 17GHz, which can satisfy 25G modulation and transmission applications.

In summary, in the laser chip in the embodiment of the present disclosure, the length of the electro-absorption modulation region is designed to be relatively long, and only a sufficiently long electro-absorption modulation region can ensure sufficient electro-absorption capability, ensure that the response speed of the device is fast enough, and increase the signal modulation speed. The quantum well in the absorption modulation area has a special structural design to ensure excellent transmission performance and further increase the signal modulation speed. At the same time, between the quantum well substrate layer and the metal electrode, between the reset layer and the metal electrode, between the quantum well top layer and the metal electrode, are filled with a silicon dioxide layer, and the setting of the silicon dioxide layer can adjust the chip capacitance to obtain a smaller The parasitic capacitance further improves the signal modulation speed. The electro-absorption modulation area in the embodiments of the present disclosure is specially designed to achieve a 25G signal modulation speed and meet the transmission distance requirement of 10 kilometers.

In the embodiment of the present disclosure, the three functions of gain, wavelength adjustment, and electrical signal modulation are concentrated on one laser chip, and at the same time, it must be suitable for large-scale manufacturing and form a simple and reliable process flow, which has become the most important and most bottleneck problem. . To this end, an embodiment of the present disclosure provides a manufacturing process of a laser chip.

In the embodiments of the present disclosure, an innovative lateral coupling process is used for the gain region and the grating region instead of the traditional tailing growth process, thereby reducing the need for an outer edge growth. Fig. 10 is a schematic diagram of a manufacturing process of a laser chip according to some embodiments, as shown in Fig. 10, the method is:

Step 1: Fig. 10(1) shows the base wafer, in which there is only the grating waveguide layer. The grating is formed by the holographic exposure method, and the area without the grating is etched to form the shape shown in Figure 10(2).

Step 2: Carry out outer edge growth, grow InP material cushion layer, waveguide layer (material is InGaAsP material with photoluminescence peak of 1380nm, 2900A), InP material stop layer, and quantum well structure in gain region in sequence, and then p-type The doped InP material, and finally a layer of InGaAsP material with a photoluminescence peak of 1250, forms a shape as shown in Figure 10(3).

Step 3: grow a thin layer of silicon dioxide on the wafer, remove the silicon dioxide layer in the grating area and the electro-absorption area by dry etching, and remove the light in the grating area and the electro-absorption area by selective wet etching InGaAsP material with a luminescence peak of 1250 and p-type doped InP material, and after removing all the silicon dioxide, a figure 10 (4) is formed.

Step 4: By selective wet etching, only the InGaAsP material is etched, and the InP material is not etched, the InGaAsP material with a photoluminescence peak of 1250 in the gain region and the gain quantum well structure in the grating region and the electroabsorption region can be removed, Thus forming the shape of Fig. 10(5). At this time, the light generated from the quantum well in the gain region will finally flow laterally into the waveguide layer and perform wavelength selection in the grating region. Finally, traditional tailing process etching and growth are carried out in the grating area and the electroabsorption area to form the shape shown in Figure 10(6).

This design provides a proven process flow: the use of lateral coupling technology reduces the loss from the gain region to the wavelength adjustment region, while simplifying the process flow and reducing the number of outer edge growths, which is suitable for mass production.

In the laser chip and optical module provided by the present disclosure, the laser chip is integrated with a gain region, a grating region and an electroabsorption modulation region. By changing the magnitude of the current injected into the grating region, the waveguide refractive index in the grating region can be continuously changed, thereby outputting different wavelengths. beam. The quantum well in the electroabsorption modulation area has a special structural design to ensure excellent transmission performance and further increase the signal modulation speed. At the same time, silicon dioxide layers are filled between the quantum well substrate layer and the metal electrode, between the reset layer and the metal electrode, and between the quantum well top layer and the metal electrode. The electro-absorption modulation area in the embodiments of the present disclosure is specially designed to achieve a 25G signal modulation speed and meet the transmission distance requirement of 10 kilometers. Therefore, the laser chip in the embodiment of the present disclosure is a chip that integrates gain, adjustable wavelength, and electrical signal modulation functions.

The laser chip provided by the embodiment of the present disclosure, firstly, can realize 25G signal modulation speed, and can meet the demand of high-speed optical fiber communication network for 25G light source; secondly, can realize wavelength adjustment range above 8nm, and the technology can be transplanted to various wavelength, not limited to dense wavelength division multiplexing applications; in the third aspect, in the face of complex functional integration requirements, the disclosed embodiments provide a proven process flow: the use of lateral coupling technology reduces the adjustment of the gain region to the wavelength The loss of the area, while simplifying the process flow, reducing the number of outer edge growth, is suitable for mass production.

The above is only a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Anyone familiar with the technical field who thinks of changes or substitutions within the technical scope of the present disclosure should cover all within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be determined by the protection scope of the claims.

Claims

A laser chip, comprising:

a gain region for generating a light beam;

a grating section for wavelength tuning the light beam from said gain section;

An electroabsorption modulation region comprising a quantum well comprising a quantum well substrate layer, a first heterojunction layer, a potential well and barrier layer, a second heterojunction layer, a reset layer, and a quantum well top layer stacked on top of each other , wherein between the quantum well substrate layer and the metal electrode, between the reset layer and the metal electrode, between the quantum well top layer and the metal electrode are all filled with a silicon dioxide layer, for The light beam in the area is signal-modulated.
The laser chip according to claim 1, wherein the gain region comprises an InP pad layer, a waveguide layer, a gain quantum well structure layer and a p-type doped InP layer stacked on each other;

The grating area includes an InP pad layer, a grating layer and a waveguide layer stacked on each other;

The electroabsorption modulation region includes an InP cushion layer and a quantum well structure layer stacked on each other;

Wherein, the waveguide layer of the grating region is the top layer of the grating region, and the quantum well structure layer of the electroabsorption modulation region is the top layer of the electroabsorption modulation region;

The waveguide layer of the gain region, the waveguide layer of the grating region and the quantum well structure layer of the electroabsorption modulation region are in the same layer.
The laser chip according to claim 1, wherein a first isolation region is provided between the gain region and the grating region, and a second isolation region is provided between the grating region and the electroabsorption modulation region.
The laser chip according to claim 1, wherein the quantum well substrate layer is an n-type InP substrate, and the first heterojunction layer, potential well and barrier layer, and the second heterojunction layer are all set as InGaAsP material with a photoluminescence peak of 1170nm, the reset layer is an InP material, and the top layer of the quantum well is a p-type InP material;

Wherein the potential well and the barrier layer include a potential well region and a potential barrier region, the potential well region has a compressibility of 0.6-0.8%, and includes 8 groups of potential wells, and the potential barrier region has a compressibility of 0.2-0.4%. slack and includes 8 sets of potential barriers.
The laser chip according to claim 3, wherein the length of the gain region is 375 μm, the length of the grating region is 150 μm, the length of the electroabsorption modulation region is 110 μm, the length of the first isolation region is 45 μm, and the The length of the second isolation region is 80 μm.
The laser chip according to claim 1, wherein the grating region includes a grating layer and a waveguide layer, the material of the grating layer is an InGaAsP material with a photoluminescence peak value of 1250nm, and a thickness of 300A, and the material of the waveguide layer is an optical InGaAsP material with a luminescence peak of 1380nm and a thickness of 2900A.
The laser chip according to claim 1, wherein the silicon dioxide layer has a thickness of 5000A.
The laser chip according to claim 1, wherein the grating layer is a distributed Bragg reflection grating formed by holographic exposure.
An optical module, comprising the laser chip according to any one of claims 1-8.