200Gbps CWDM EML laser
By optimizing the epitaxial and chip processes of the 200Gbps CWDM EML laser and integrating the DFB laser diode, EA modulator, and PQ waveguide, the reliability problem of the existing 200G PAM4 EML laser was solved, achieving higher reliability and performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUJIAN Z K LITECORE LTD
- Filing Date
- 2025-04-24
- Publication Date
- 2026-05-12
AI Technical Summary
The existing 200G PAM4 EML laser is insufficient in terms of reliability and cannot meet the needs of future high-speed data center modules.
A 200Gbps CWDM EML laser is designed. By optimizing the epitaxial PL, grating period, and chip process, a DFB laser diode, an EA modulator, and a PQ waveguide are integrated to form a four-segment docking region, which protects the active region and improves product reliability.
This improved product reliability, met the requirements of high-speed data center modules, and achieved higher performance and stability.
Smart Images
Figure CN224233134U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of high-speed EML laser technology, and in particular to a 200Gbps CWDM EML laser. Background Technology
[0002] Driven by global AI computing power growth and domestic demand from the "Eastern Data, Western Computing" project, demand for data center modules continues to grow, with a CAGR of approximately 10%. High-speed modules, particularly 400G / 800G, are expected to be the focus of growth over the next 3-5 years (approximately 10-15 million units). Demand is primarily driven by North America, with domestic data centers adopting a follower strategy.
[0003] Industry reports indicate that demand for 400G / 800G high-end modules in China primarily comes from companies such as Alibaba, Tencent, Baidu, ByteDance, and Huawei. The generational transition in domestic data centers lags behind North America by at least 1-2 years. Demand for 400G has been gradually increasing since 2023, and the total demand for 400G to 800G and above specifications is projected to reach approximately 500,000 units in 2024 (a conservative estimate). Demand growth has been around 100% in recent years.
[0004] From the perspective of high-end module solutions, silicon photonics solutions and the soon-to-be-commercialized 200G PAM4 CWDM EML will replace part of the 100G PAM4 EML market. Currently, silicon photonics module shipments are estimated to account for no more than 30%, and are not expected to exceed 50% in the next 1-2 years. 200G PAM4 EML shipments are relatively lower due to maturity issues. Therefore, there is still significant market potential for 200G PAM4 EML in the future. The reliability of existing 200G PAM4 EML technologies in applications still needs improvement. Utility Model Content
[0005] In view of this, the purpose of this utility model is to provide a 200Gbps CWDM EML laser. Through the design of epitaxial PL, grating period, chip process, etc., an integrated chip is fabricated. This structural design takes advantage of the temperature of AlGaInAs active material and protects the active region through PQ waveguide docking, thereby further improving the reliability of the product.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: a 200Gbps CWDM EML laser, wherein the EML consists of four docking regions, specifically: the first docking region is formed by docking one end of the PQ waveguide with the DFB laser diode; the second docking region is formed by docking the other end of the DFB laser diode with the isolation region PQ waveguide; the third docking region is formed by docking one end of the isolation region PQ waveguide with the EA modulator; and the fourth docking region is formed by docking the other end of the EA modulator with the PQ waveguide. A total of four docking regions are integrated on one EML laser, and the PQ waveguide, DFB laser diode, and EA modulator are designed on the same ridge waveguide.
[0007] In a preferred embodiment: a PQ waveguide is provided at one end of both the DFB laser diode and the EA modulator; and a common isolation region PQ waveguide is provided between the DFB laser diode and the EA modulator; the length of the DFB is 300-400um, and the length of the EA is 50-150um.
[0008] In a preferred embodiment, both the DFB laser diode and the EA modulator have a PQ waveguide section with a length of 15-30 μm at one end.
[0009] In a preferred embodiment, the length of the common isolation region PQ waveguide between the DFB laser diode and the EA modulator is 30-80µm.
[0010] In a preferred embodiment, the ridge waveguide width is 2.0-3.0 μm.
[0011] Compared with existing technologies, this utility model has the following advantages: Compared with solutions such as Identical and SAG, it not only leverages the temperature advantage of AlGaInAs active materials, but also protects the active region through PQ waveguide docking, further improving the reliability of the product. Attached Figure Description
[0012] Figure 1 This is a diagram of the epitaxial layer structure of the 200Gbps CWDM EML laser according to an embodiment of this utility model;
[0013] Figure 2 This is a schematic diagram of the chip of the 200Gbps CWDM EML laser according to an embodiment of this utility model;
[0014] Figure 3 This is a 3D schematic diagram of the chip of the 200Gbps CWDM EML laser according to an embodiment of this utility model;
[0015] Figure 4 This is the LIV test data of the 200Gbps CWDM EML laser in this embodiment of the invention;
[0016] Figure 5 This is the bandwidth test data of the 200Gbps CWDM EML laser in this embodiment of the utility model;
[0017] Figure 6 This is the eye diagram test data of the 200Gbps CWDM EML laser in this embodiment of the present invention. Detailed Implementation
[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0020] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.
[0021] This invention provides a 200Gbps CWDM EML laser. (Reference) Figure 1-6 Its design integrates a DFB laser diode, an EA modulator, and a PQ waveguide, each with a different structure. The integrated chip is fabricated through the design of epitaxial PL, grating period, and chip process.
[0022] The key point is that the PQ waveguide is connected to the DFB laser diode at one end, the DFB at the other end is connected to the isolation PQ waveguide, the isolation PQ waveguide is then connected to the EA modulator at the other end, and the EA modulator at the other end is connected to the PQ waveguide. A total of four interconnected sections are integrated on a single EML laser, and the PQ waveguide, DFB laser diode, and EA modulator are all designed on the same ridge waveguide.
[0023] The docking structure design consists of four docking sections: the PQ waveguide docks with the DFB laser diode, the other end of the DFB docks with the isolation PQ waveguide, the isolation PQ waveguide then docks with the EA modulator, and the other end of the EA docks with the PQ waveguide. Both ends of the DFB laser diode and the EA modulator have a PQ waveguide docking section, with waveguide lengths of 15-30µm; there is also a common isolation PQ waveguide between the DFB and EA, with isolation section lengths of 30-80µm; the DFB length is 300-400µm, the EA length is 50-150µm, and the ridge waveguide width is 2.0-3.0µm.
[0024] Based on this, the design structure of the 200Gbps CWDM EML laser is grown sequentially as follows: a base wafer is grown on an InP substrate by MOCVD, including an N-InP buffer layer (500-900nm), an InGaAlAs lower waveguide layer (50-80nm), an AlGaInAs active layer (80-110nm), an InGaAlAs upper waveguide layer (30-50nm), a P-InAlAs electron blocking layer (30-60nm), a P-InP spacer layer (30-60nm), a P-InGaAsP etch stop layer (10-20nm), a P-InP spacer layer (40-60nm), a P-InGaAsP grating layer (20-30nm), and a P-InP protective layer (20-50nm).
[0025] Furthermore, on the base wafer, gratings are fabricated only in the DFB region using holographic exposure and partial grating etching techniques, with the gratings occupying 40-70% of the DFB region. Epitaxy is then performed to embed InP with a embedding thickness of 130-170 nm. A 100-300 nm SiO2 mask layer is then grown on its surface, and the LD region is fabricated using photolithography and etching. The remaining regions are etched using ICP and wet etching down to 50-200 nm below the lower waveguide, and then epitaxy is performed for the mating growth of the EA structure. The EA growth includes an N-InP buffer layer (50-200 nm, compensated based on the previous etching depth to the lower waveguide), an N-InAlAs layer (20-30 nm), an InGaAlAs lower waveguide layer (20-30 nm), an AlGaInAs active layer (140-170 nm), an InGaAlAs upper waveguide layer (20-30 nm), a P-InAlAs electron blocking layer (20-30 nm), and a P-InP... Spacer layer (40-70nm), P-InGaAsP etch stop layer (20-30nm, must be flush with DFB etch stop layer), P-InP protective layer (200-300nm, must be flush with DFB surface layer).
[0026] Further, after removing SiO2, a 100-300nm SiO2 mask layer is regrown. New LD and EA regions are fabricated by photolithography etching. The remaining regions are etched using ICP etching and wet etching to a depth of 50-200nm below the lower waveguide. Then, the layer is sent for epitaxy to grow the PQ waveguide. The PQ waveguide includes a U-InP buffer layer (50-200nm, compensated according to the depth of the previous etching to the lower waveguide), a U-InGaAsP waveguide layer (200-250nm), a U-InP protective layer (40-70nm), and a U-InGaAsP etching stop layer. The epitaxial layer consists of a stop layer (20-30nm, flush with the DFB etching stop layer) and a U-InP protective layer (200-300nm, flush with the DFB surface layer). After the SiO2 layer is removed by wet process, the epitaxial layer is sent for final embedding. The embedded layer contains a P-InP space layer (1600-2000nm), a P-InGaAsP transition layer (40-70nm), a P-InGaAs ohmic contact layer (200-300nm), and a P-InP protective layer (20-30nm), forming the final epitaxial wafer.
[0027] Further, a 100-300nm SiO2 mask layer is first grown on the epitaxial wafer, and then a ridge waveguide layer with a width of 2.0-3.0µm is prepared by photolithography wet processing. After removing all SiO2, a 200-400nm SiO2 layer is grown. Ridge opening and shallow etching are performed at the junction of DFB and EA, etching down to 2 / 3 of the P-InP thickness, thus completing the isolation region process. After removing SiO2, a 150-250nm Si3N4 layer is grown. Ridge opening and ID metal lithography are then performed on DFB and EA, and Ti-Au (50-100nm) metal is deposited on the P-side and alloyed. Next, a BCB process is performed, leaving a 2-3µm thick BCB layer in the EA region. A 150-250nm layer is then grown. Si3N4 is used, and ridge openings are made for DFB and EA, and Ti-Pt-Au metal is deposited on the P-side (50-100-100nm) and thick gold Au is electrolessly deposited (1500nm). Then, thinning is carried out to a thickness of 90-120um, with GeAu-Ni-Au metal and N-side alloy deposited. Finally, optical films are deposited, completing the chip fabrication. Figure 2 , Figure 3 .
[0028] Specifically, the design structure of the 200Gbps CWDM EML laser is as follows: Figure 1As shown, first, an N-InP buffer layer 1 (500-900nm) is grown on the InP sub-layer 0; then, an InGaAlAs lower waveguide layer 2 (50-80nm) is grown; then, an AlGaInAs active layer 3 (80-110nm) is grown; then, an InGaAlAs upper waveguide layer 4 (30-50nm) is grown; then, a P-InAlAs electron blocking layer 5 (30-60nm) is grown; then, a P-InP Spacer layer 6 (30-60nm) is grown; then, a P-InGaAsP etch stop layer 7 (10-20nm) is grown; then, a P-InP Spacer layer 8 (40-60nm) is grown; then, a P-InGaAsP grating layer 9 (20-30nm) and a P-InP protective layer 10 (20-50nm) are grown.
[0029] Next, using holographic exposure and partial grating etching techniques, a grating is fabricated that occupies only the DFB region, with a grating duty cycle controlled at 40-70% and covering 40-70% of the DFB region. Then, an epitaxial growth layer of InP is performed with a buried thickness of 130-170 nm. Finally, a 100-300 nm layer is grown on its surface. The SiO2 mask layer is used to fabricate the LD region by photolithography etching. The remaining regions are etched by ICP and wet etching down to 50-200 nm below the lower waveguide layer 2, and then sent for epitaxy to grow the EA structure. The EA growth includes, in sequence, an N-InP buffer layer (50-200 nm, compensated according to the previous etching depth to the lower waveguide), an N-InAlAs layer (20-30 nm), an InGaAlAs lower waveguide layer (20-30 nm), an AlGaInAs active layer (140-170 nm), an InGaAlAs upper waveguide layer (20-30 nm), a P-InAlAs electron blocking layer (20-30 nm), a P-InP spacer layer (40-70 nm), a P-InGaAsP etch stop layer (20-30 nm, which needs to be flush with the DFB etch stop layer 7), and a P-InP protective layer (200-300 nm, which needs to be flush with the DFB surface InP layer 11).
[0030] Next, after removing SiO2, a 100-300nm SiO2 mask layer is regrown. New LD and EA regions are fabricated using photolithography. The remaining regions are etched using ICP and wet etching down to 50-200nm below the lower waveguide layer 2. Then, epitaxy is performed for the mating growth of the PQ waveguide. The PQ waveguide sequentially includes a U-InP buffer layer (50-200nm, compensated based on the previous etching depth to the lower waveguide), a U-InGaAsP waveguide layer (200-250nm), a U-InP protective layer (40-70nm), and a U-InGaAsP etch stop layer (200-70nm). -30nm, which needs to be flush with the DFB etching stop layer 7), U-InP protective layer (200-300nm, which needs to be flush with the DFB surface InP layer 11); after the SiO2 layer is removed by wet process, it is sent for epitaxy for final burial, which buries P-InP space layer 12 (1600-2000nm), P-InGaAsP transition layer 13 (40-70nm), P-InGaAs ohmic contact layer 14 (200-300nm) and P-InP protective layer 15 (20-30nm), forming the final epitaxial wafer.
[0031] After fabrication of a 200Gbps CWDM EML laser, as follows Figure 3 As shown, the specific preparation steps are as follows:
[0032] 1) First, grow a 100-300nm SiO2 mask layer on the epitaxial wafer, and then prepare a ridge waveguide layer by photolithography wet process. The width of the ridge waveguide is 2.0-3.0um. After removing all SiO2, grow another 200-400nm SiO2 layer.
[0033] 2) Perform ridge opening and shallow etching at the junction of DFB and EA until 2 / 3 of the P-InP thickness remains, thus completing the isolation zone process. Remove SiO2 and grow a 150-250nm Si3N4 layer.
[0034] 3) Then, ridge opening and ID metal lithography are performed on DFB and EA, and a Ti-Au layer 17 (50-100nm) is deposited on the P-side and alloyed;
[0035] 4) Next, arrange the BCB process to retain a 2-3 μm thick BCB layer in the EA region 18; then regenerate a 150-250 nm Si3N4 layer 19;
[0036] 5) Then, ridge opening and P-side metal Ti-Pt-Au (50-100-100nm) vapor deposition and thick gold Au (1500nm) electroless plating are performed on DFB and EA, with DFB having a gold layer of 20 and EA having a gold layer of 21.
[0037] 6) Then, thinning is arranged to a thickness of 90-120um, with N-side metal GeAu-Ni-Au and N-side alloy, followed by strip-depositing of the optical film, thus completing the chip fabrication. Figure 2 , Figure 3 As shown.
[0038] In subsequent LIV chip testing, at T=50℃, the Pf power reached 13.85mW @80mA (e.g., Figure 4 As shown); COC-level chip bandwidth test (such as...) Figure 5 As shown) reaching 67GHz or higher (using a 67GHz network divider, exceeding the upper limit of the testing instrument); and in 200Gbps PAM4 COC-level eye diagram testing (such as... Figure 6 (As shown) all achieved good results.
[0039] This patent is not limited to the preferred embodiment. Anyone can derive other forms of 200Gbps (and below) CWDM EML lasers and their fabrication methods based on the teachings of this patent. All equivalent variations and modifications made within the scope of this utility model application should be covered by this patent.
Claims
1. A 200Gbps CWDM EML laser, characterized in that, The EML consists of four docking regions: the first docking region is formed by docking one end of the PQ waveguide with one end of the DFB laser diode; the second docking region is formed by docking the other end of the DFB laser diode with the isolation region PQ waveguide; the third docking region is formed by docking one end of the isolation region PQ waveguide with one end of the EA modulator; and the fourth docking region is formed by docking the other end of the EA modulator with the PQ waveguide. These four docking regions are integrated into one EML laser, and the PQ waveguide, DFB laser diode, and EA modulator are designed on the same ridge waveguide.
2. The 200Gbps CWDM EML laser according to claim 1, characterized in that: Both the DFB laser diode and the EA modulator have a PQ waveguide connection at one end; and there is a common isolation region PQ waveguide between the DFB laser diode and the EA modulator; the length of the DFB is 300-400um, and the length of the EA is 50-150um.
3. A 200Gbps CWDM EML laser according to claim 1, characterized in that: Both the DFB laser diode and the EA modulator have a PQ waveguide section at one end, with a length of 15-30µm.
4. A 200Gbps CWDM EML laser according to claim 1, characterized in that: The common isolation zone PQ waveguide between the DFB laser diode and the EA modulator is 30-80µm in length.
5. A 200Gbps CWDM EML laser according to claim 1, characterized in that: The ridge waveguide width is 2.0-3.0 μm.