Multi-channel multi-wavelength semiconductor laser light source device for optical I / O

Abstract

The utility model discloses a multi-channel multi-wavelength semiconductor laser light source device for optical I / O. A parallel multi-wavelength semiconductor DFB laser array prepared based on REC technology, a beam splitting / routing device under different material systems and an optical fiber array FA are connected through optical coupling components, and a large number of laser channels are integrated. The parallel multi-wavelength semiconductor DFB laser array prepared on the basis of the REC technology is good in single longitudinal mode stability and accurate in wavelength control, the stability and improvement of the performance of a data transmission system are facilitated, the PWB waveguide coupling mode can be adopted, integration of a large number of laser channels can be achieved more easily, and the integration efficiency is improved. The size of the device is further reduced, and the device has better mechanical reliability.

Description

TECHNICAL FIELD

[0001] The utility model relates to III-V semiconductor laser technology and photon integration technical field, especially to a kind of multi-channel multi-wavelength semiconductor laser light source device for light I / O (Optical I / O). BACKGROUND

[0002] With the gradual popularization of intelligent transportation, industrial brain, automatic driving, Internet of Things and other artificial intelligence (AI) applications, diversified data sources such as voice, image and video are emerging day by day. This brings unprecedented challenges to today's data centers and edge devices. At the same time, in order to improve the quality and accuracy of AI applications, AI models are constantly developing and the parameter scale is constantly expanding. This makes the computing demand of the model for each unit of input data become more massive, further increasing the computing complexity of processing massive data. Due to signal integrity problems, in the package with limited number of pins, as the data rate increases to 112Gb / s and above, electrical I / O is rapidly approaching the performance limit, but due to the limitation of electrical I / O outside the package, most of them are output to the high bandwidth memory (HBM) in the joint package. Intra-package electrical I / O technology, such as wide parallel interface for HBM and logic chip-to-chip communication, has the highest bandwidth density and energy efficiency, but can only span a few millimeters, requiring more power-consuming SerDes electrical links. Electrical I / O has great limitations in power efficiency, data delay, bandwidth density and transmission distance. Optical I / O technology aims to solve the interconnection problem between computing chips through optical interconnection technology, replacing the traditional electrical interconnection scheme. Optical I / O uses its low power consumption, high bandwidth and low delay characteristics to build a distributed computing network, thereby realizing the pooling of computing resources.

[0003] Multi-wavelength laser can simultaneously oscillate multiple wavelengths, and multiple wavelengths are simultaneously modulated by a micro-ring modulator array in the connection of optical I / O, which can greatly improve the capacity of information. The current research on the implementation of multi-wavelength laser mainly includes parallel multi-wavelength array structure, optical frequency comb structure and mode-locked laser. The optical frequency comb structure has the advantages of good coherence and precise wavelength spacing by injecting specific microcavity structure with pump light to generate frequency comb with equal frequency spacing, but the number of comb teeth generated is large, the power of each wavelength is low, and the generation of frequency comb requires high-quality microcavity, which increases the processing difficulty. The generation of frequency comb is generally through optical pumping, and the energy conversion efficiency is low, so it is difficult to realize monolithic integration of the whole system. The mode-locked laser generally generates multi-wavelength frequency comb through active or passive mode-locking technology. However, it also has the problems of large number of frequency comb and low power of single wavelength. In addition, the mode-locked laser often realizes the mode-locking function through a discrete system, which has a large volume and power consumption, and it is difficult to realize monolithic integration. In addition, the above two schemes are difficult to independently adjust a single wavelength, which poses a challenge to the control and stability of the subsequent communication system. The parallel multi-wavelength distributed feedback (DFB) laser array structure is a common method to realize multi-wavelength laser. The DFB laser has the advantage of stable mode, so by monolithic integration of multiple DFB laser units, each DFB laser is set to different wavelengths, so the function of multiple wavelengths can be realized, and each wavelength has high power, and the single wavelength can be independently adjusted. However, since each wavelength is output from a different waveguide, a monolithic or discrete optical coupler is needed to realize the function of combining waves, which on the one hand will cause the loss of optical power, and on the other hand will increase the difficulty of processing and manufacturing. Content of the utility model

[0004] The utility model aims at providing a kind of multi-channel multi-wavelength semiconductor laser light source device for optical I / O for solving the size of multi-channel multi-wavelength light source system, single wavelength power is low, wavelength precision control is difficult.

[0005] Technical Solution: The multi-channel, multi-wavelength semiconductor laser source device for optical I / O described in this utility model includes a parallel multi-wavelength semiconductor DFB laser array fabricated based on Reconstruction-Equivalent Chirp (REC) technology, a first optical coupling component, an optical beam splitter / router component, a second optical coupling component, and a fiber array (FA). The first optical coupling component connects the DFB laser array and the optical beam splitter / router, and the second optical coupling component connects the optical beam splitter / router and the fiber array (FA). The parallel multi-wavelength semiconductor DFB laser array provides a laser source of multiple wavelengths, and each row of output waveguides in the parallel multi-wavelength semiconductor DFB laser array integrates a semiconductor optical amplifier. The optical amplifier (SOA) is used to independently adjust the output power of each laser to achieve output power equalization. The optical beam splitter / router includes M input ports and N output ports, where 1 ≤ N ≤ M. The output optical power is adjusted by regulating the input current of the SOA. The optical beam splitter / router is used to evenly distribute all input optical signals of different wavelengths to the corresponding output ports, so that each output channel has an equal amount of optical signals of all input wavelengths. The second coupling component is used to adjust and conduct the optical mode of the output light of the optical beam splitter / router, so that the mode of the optical signal emitted from the output end of the optical beam splitter / router can match the optical mode in the FA waveguide. The multi-wavelength optical signals of all channels of the fiber array FA are connected to external devices through pigtails.

[0006] Furthermore, the optical beam splitter / router is an optical beam splitter / router made of at least one of silicon nitride (Si3N4), silicon dioxide, silicon, or passive InP.

[0007] Preferably, the optical beam splitter / router is any one of a multi-mode inferometer (MMI), a star coupler, or an arrayed waveguide grating (AWG). An MMI confines the mode field of the optical signal within the core layer using the refractive index difference between the waveguide core and cladding materials, and achieves arbitrary-order self-imaging at the output waveguide position based on multi-mode interference. A star coupler achieves free-space coupling of the input optical field by inserting a planar waveguide region between the symmetrical fan-shaped input and output waveguide arrays. An AWG, based on the interference theory of monochromatic light passing through different optical path thicknesses, achieves efficient coupling of input light of different wavelengths and couples corresponding beam splitters at the output end to form a combined unit. All three methods can achieve power equalization across multiple output ports for all multi-wavelength input light from the DFB laser array.

[0008] Furthermore, the first optical coupling component is a photonic wire bonding (PWB) polymer waveguide or array lens, which performs optical mode adjustment and transmission of the output light; the second optical coupling component is a waveguide-fiber waveguide or a PWB polymer waveguide.

[0009] Furthermore, the parallel multi-wavelength semiconductor DFB laser array (1) fabricated based on REC technology includes, from bottom to top, a substrate, a buffer layer, a lower confinement layer, a multi-quantum well layer, an upper confinement layer, a grating layer, an etching barrier layer, a waveguide layer, and a contact layer; wherein, the grating layer is composed of a laser grating.

[0010] Furthermore, an equivalent phase shift or equivalent chirp, or both, can be introduced into the resonant cavity of the DFB laser.

[0011] Furthermore, the multiple quantum well layer serves as a gain medium, and its gain wavelength range is not less than the output wavelength range of the semiconductor laser device. The multiple quantum well layer is an InGaAlAs multiple quantum well.

[0012] Furthermore, the optical fiber in the fiber array FA is a polarization-maintaining fiber.

[0013] Beneficial Effects: Compared with the prior art, this utility model has the following advantages: This utility model adopts a parallel multi-wavelength DFB laser array based on REC technology, which has the advantages of good single-longitudinal mode stability and precise wavelength control. Compared with optical frequency comb structures and mode-locked lasers, the DFB laser array can freely select the required number of wavelengths (i.e., the number of lasers) and has high single-wavelength power, which is more conducive to the stability and improvement of data transmission system performance. If PWB waveguide coupling is used, compared with the traditional discrete device optical coupling method, it is easier to integrate a large number of laser channels, further reduce the device size, and also have better mechanical reliability. In addition, compared with other hybrid integration processes, PWB process has a fast processing speed, is conducive to mass production, and also helps to reduce the overall manufacturing cost. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model;

[0015] Figure 2 A schematic diagram of a parallel multi-wavelength semiconductor DFB laser array;

[0016] Figure 3 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0017] Figure 4 This is a simulation diagram of the optical field transmission at a wavelength of 1550nm in Example 1;

[0018] Figure 5 Schematic diagram of the PWB waveguide fabrication process;

[0019] Figure 6 This is a schematic diagram of the PWB polymer waveguide shape of the parallel multi-wavelength semiconductor DFB laser array and MMI input waveguide in Example 1;

[0020] Figure 7 This is a schematic diagram of the PWB polymer waveguide connecting the MMI output waveguide and the FA in Example 1;

[0021] Figure 8 The eight-channel spectrum measured in Example 1;

[0022] Figure 9 This is a schematic diagram of the structure of Embodiment 2 of this utility model. Detailed Implementation

[0023] The technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0024] The multi-channel, multi-wavelength semiconductor laser source device for optical I / O described in this invention includes a parallel multi-wavelength semiconductor DFB laser array 1 fabricated based on REC technology, a first optical coupling component 2, an optical beam splitter / router component 3, a second optical coupling component 4, and an optical fiber array FA5. The first optical coupling component 2 connects the DFB laser array and the optical beam splitter / router, and the second optical coupling component 4 connects the optical beam splitter / router 3 and the optical fiber array FA5. Each row of output waveguides in the parallel multi-wavelength semiconductor DFB laser array 1 integrates a semiconductor optical amplifier (SOA). The optical beam splitter / router 3 includes M input ports and N output ports, where 1 ≤ N ≤ M. The second coupling component 4 is used to adjust and guide the output light of the optical beam splitter / router to match the optical mode of the optical fiber array FA5. The multi-wavelength optical signals of all channels of the optical fiber array FA5 are connected to external devices via pigtails 6. The optical fiber of the optical fiber array FA5 is a polarization-maintaining fiber 10.

[0025] The optical beam splitter / router 3 is an optical beam splitter / router made of at least one of silicon nitride (Si3N4), silicon dioxide, silicon, or passive InP, and can be any one of a multimode interferometer (MMI), a star coupler, or an arrayed waveguide grating (AWG).

[0026] The parallel multi-wavelength semiconductor DFB laser array 1, fabricated using REC technology, comprises, from bottom to top, a substrate, a buffer layer, a lower confinement layer, a multiple quantum well layer, an upper confinement layer, a grating layer, an etch-blocking layer, a waveguide layer, and a contact layer; wherein the grating layer is composed of a laser grating. An equivalent phase shift or equivalent chirp, or both, is introduced into the DFB laser resonant cavity. The multiple quantum well layer serves as the gain medium, and its gain wavelength range is not less than the output wavelength range of the semiconductor laser device; the multiple quantum well layer is an InGaAlAs multiple quantum well.

[0027] The semiconductor DFB laser array 1 based on REC technology is fabricated using the following steps: a buffer layer and a lower confinement layer are sequentially grown on a substrate by metal-organic compound vapor deposition, followed by the growth of a multi-quantum well layer on the lower confinement layer, an upper confinement layer on the multi-quantum well layer, and a grating layer above the upper confinement layer. The grating layer is a laser grating designed using reconstructed equivalent chirp technology, with an equivalent π phase shift structure introduced at the center of the DFB laser grating region. InP is deposited above the grating layer to bury it, followed by the sequential growth of an etching barrier layer, a waveguide layer, and a contact layer. The waveguide layer and contact layer are etched to form ridges, and electrical isolation is etched to achieve partitioning. A front metal electrode is grown in the ridge region above the contact layer. The back side of the substrate is thinned and polished, the back electrode is evaporated and heated to obtain an alloy, and the semiconductor multi-wavelength laser array is obtained after chip cleaving.

[0028] The first optical coupling component 2 is a PWB polymer waveguide or an array lens, and the second optical coupling component 4 is a waveguide-fiber waveguide or a PWB polymer waveguide. The PWB polymer waveguide fabrication process includes: First, fixing the optical component chips to be integrated into the PWB onto a common substrate 17; during processing, first fixing the workpiece, including the substrate, semiconductor DFB laser array 18, optical beam splitter / router device 19, and FA 20, and then covering the entire processing area with PWB photoresist 21, i.e., the two chip end faces to be connected and all areas in between; then, using a high-magnification objective lens 22, using confocal imaging or layer-by-layer imaging methods, combined with an image recognition algorithm designed for a specific waveguide, identifying the normals of the input and output port faces of the waveguide to be connected, identifying the waveguide structure diagram, and determining the position and shape of the polymer waveguide; using a laser direct writing system with a high-precision motion control system, focusing the output light of the femtosecond laser to the position 23 where the waveguide end needs to be formed, completing the exposure and forming of the polymer waveguide 24; then washing away the unpolymerized photoresist 21 through a development process, leaving the polymer-formed connecting waveguide.

[0029] Optical wire bonding (OFCH) is a method for heterogeneous chip integration proposed in recent years. It utilizes the strong nonlinear effect of ultrafast laser pulses to generate strong frequency-doubled short-wavelength photons near the beam's focal point, inducing the polymerization of photosensitive resin materials to form polymer optical waveguides, thus achieving optical coupling between heterogeneous optical chips. This technology is particularly suitable for multi-channel heterogeneous hybrid integration applications, offering advantages such as fast processing speed, high coupling efficiency, small size, and good reliability of optical leads against vibration and temperature changes. It effectively solves the problem of optical interconnection between photonic integrated chips in different material systems, improving chip performance while maintaining advantages such as small size and low power consumption.

[0030] Example 1

[0031] An 8-channel, 8-wavelength optical I / O source based on an 8-wavelength parallel DFB semiconductor laser array 12 manufactured using REC technology and a silicon-based 8×8 MMI14, such as... Figure 3 As shown.

[0032] The 8-wavelength parallel DFB semiconductor laser array 12 is a laser with selectable lasing wavelength. It can use an n-type doped substrate. An n-type doped InP buffer layer, an n-type doped confinement layer, and an undoped confinement layer are sequentially grown on the substrate by metal-organic compound vapor deposition. The confinement layer is used to confine the optical field and confine the charge carriers. Then, an InGaAlAs multi-quantum-well structure is grown. A confinement layer is designed above the quantum wells. An InGaAsP grating layer is grown above the confinement layer. The grating layer is prepared using the reconstructed equivalent chirp technique. The π phase shift grating structure introduced at the center of the laser grating region ensures that the laser device achieves good single-longitudinal-mode lasing output and wavelength control. A p-type InP is grown above the grating layer for burial. A waveguide layer and a related etching barrier layer are grown above the contact layer. Then, the waveguide layer is grown.

[0033] The 8-wavelength parallel DFB semiconductor laser array 12 consists of 8 lasers, each with a cavity length of 1000 μm. A semiconductor optical amplifier (SOA11) is monolithically integrated at the front end of each laser to independently adjust the output power of each laser, achieving output power equalization. Each SOA is 300 μm long. The grating period of the parallel 8 lasers has a linear variation. Through the design of the equivalent sampling period of the grating in the reconstruction equivalent chirp technique, the grating Bragg wavelength is achieved, i.e., the output wavelength linearly varies from 1541.3 nm to 1552.5 nm. A multi-quantum well layer serves as the gain medium, covering the wavelength output range of the multi-wavelength array laser. The multi-quantum wells provide the required gain, and the gain spectrum design covers the wavelength output range. Preferably, the multi-quantum well layer is an InGaAlAs multi-quantum well; the substrate is an n-type doped substrate, and the lower confinement layer consists of n-type doped and undoped confinement layers.

[0034] An 8-wavelength parallel DFB semiconductor laser array 12 is mounted on a ceramic substrate by eutectic bonding; electrical signal transmission lines and electrodes that meet the laser injection current transmission requirements are arranged on the ceramic substrate by gold plating, and the electrodes are connected to the electrodes of the laser array by gold wire bonding.

[0035] The silicon-based 8×8 MMI14 has eight input and eight output waveguides, all of which are single-mode SOI waveguides with a width of 450 nm and a height of 220 nm. The multimode waveguide in the MMI has a width of 20 μm, a length of 351 μm, and a height of 220 nm. The input and output waveguides and the multimode waveguide in the MMI are connected by a transition tapered waveguide with a top width of 450 nm, a bottom width of 2 μm, a length of 20 μm, and a height of 220 nm. The silicon-based 8×8 MMI14 can evenly distribute all eight different wavelengths of input optical signals to all eight output ports, ensuring that each output channel has an equal amount of optical signal of all input wavelengths.

[0036] The silicon-based 8×8 MMI14 waveguide is fabricated using silicon waveguide processing technology: First, an oxidation process is performed on the silicon wafer to form a micron-sized SiO2 oxide insulating layer. Then, a 1-2 micron-thick Si layer is epitaxially grown on top of this layer using methods such as plasma-enhanced chemical vapor deposition (PECVD). Using photolithography and etching, a ridge-shaped silicon waveguide is fabricated on the topmost Si layer, while the underlying Si layer is also thinned by etching. Finally, a SiO2 cladding layer is grown on the finished surface to protect the ridge structure and stabilize optical performance, taking into account symmetry. Figure 5 Only the optical field transmission effect of the designed silicon-based 8×8 MMI was shown when the input light was at ports 1, 2, 3, and 4, respectively;

[0037] The fabrication process of the PWB polymer waveguide 13 connecting the DFB laser array and the MMI input waveguide, and the PWB polymer waveguide 15 connecting the MMI output waveguide and the FA, includes: First, fixing the optical component chips to be PWB integrated onto a common substrate 17; during processing, first fixing the workpiece, including the substrate, the semiconductor DFB laser array 18, the silicon-based 8×8 MMI 14, and the FA 20, and then covering the entire processing area with PWB photoresist 21, i.e., the two chip end faces to be connected and all the areas in between; Subsequently, using a high-magnification objective lens 22, confocal imaging or layer-by-layer imaging methods, combined with an image recognition algorithm designed for a specific waveguide, are employed in the observation system to identify the normals of the input and output port surfaces of the waveguides to be connected, thereby identifying the waveguide structure diagram and determining the position and shape of the polymer waveguide. Using a laser direct-writing system with a high-precision motion control system, the output light of the femtosecond laser is focused onto the position 23 where the waveguide end needs to be formed, completing the exposure and shaping of the polymer waveguide 24. Afterward, the unpolymerized photoresist 21 is washed away through a development process, leaving the connecting waveguide formed by the polymer.

[0038] The PWB lead morphology for PWB polymer waveguide 13 connecting the laser array to the 8×8 MI and PWB polymer waveguide 15 connecting the 8×8 MI to the FA is as follows: Figure 6 and Figure 7 As shown, the spacing 25 along the light propagation direction is generally 150–350 μm. On the plane perpendicular to the optical axis, the errors in the horizontal position 26 and the vertical position 27 between the ports should be minimized, with a maximum error not exceeding 20 μm.

[0039] The 8-channel output spectrum measured in this embodiment is as follows: Figure 8 As shown.

[0040] Example 2

[0041] The difference between this embodiment and embodiment 1 is that the optical beam splitter / router device is an arrayed waveguide grating (AWG).

Claims

1. A multi-channel multi-wavelength semiconductor laser light source device for optical I / O, characterized by, The parallel multi-wavelength semiconductor DFB laser array (1), a first optical coupling component (2), an optical beam splitting / routing device (3), a second optical coupling component (4) and a fiber array FA (5) are prepared based on the REC technology, the first optical coupling component (2) is used for connecting the DFB laser array and the optical beam splitting / routing device, the second optical coupling component (4) is used for connecting the optical beam splitting / routing device (3) and the fiber array FA (5); each row of output waveguides of the parallel multi-wavelength semiconductor DFB laser array (1) is integrated with a semiconductor optical amplifier SOA; the optical beam splitting / routing device (3) comprises M input ports and N output ports, 1≤N≤M; the second coupling component (4) is used for optical mode adjustment and conduction of output light of the optical beam splitting / routing device, matching the optical mode of the fiber array FA (5), and multi-wavelength optical signals of all channels of the fiber array FA (5) are connected with external devices through a pigtail (6).

2. The multi-channel multi-wavelength semiconductor laser optical source device for optical I / O of claim 1, wherein, The optical beam splitting / routing device (3) is an optical beam splitting / routing device made of at least one of silicon nitride Si3N4, silicon dioxide, silicon or passive InP.

3. The multi-channel multi-wavelength semiconductor laser light source device for optical I / O according to claim 1, wherein, The optical beam splitting / routing device (3) is any one of a multimode interference device (MMI), a star coupler or an arrayed waveguide grating (AWG).

4. The multi-channel multi-wavelength semiconductor laser optical source device for optical I / O of claim 1, wherein, The first optical coupling component (2) is a PWB polymer waveguide or an array lens, and the second optical coupling component (4) is a waveguide-fiber waveguide or a PWB polymer waveguide.

5. The multi-channel multi-wavelength semiconductor laser light source device for optical I / O according to any one of claims 1 to 4, wherein, The parallel multi-wavelength semiconductor DFB laser array (1) prepared based on the REC technology comprises, from bottom to top, a substrate, a buffer layer, a lower confinement layer, a multi-quantum well layer, an upper confinement layer, a grating layer, an etching stop layer, a waveguide layer and a contact layer; wherein the grating layer is composed of a laser grating.

6. The multi-channel multi-wavelength semiconductor laser light source device for optical I / O according to any one of claims 1 to 4, wherein, An equivalent phase shift or an equivalent chirp is introduced into the DFB laser resonant cavity, or an equivalent phase shift and an equivalent chirp are simultaneously introduced.

7. The multi-channel multi-wavelength semiconductor laser optical source device for optical I / O of claim 5, wherein, The multi-quantum well layer serves as a gain medium, and a gain wavelength range thereof is not less than an output wavelength range of the semiconductor laser device, and the multi-quantum well layer is an InGaAlAs multi-quantum well.

8. The multi-channel multi-wavelength semiconductor laser light source device for optical I / O according to any one of claims 1 to 4, wherein, The optical fibers of the fiber array FA (5) are polarization maintaining optical fibers.

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