China's first 1.6Tb/s silicon photonic interconnect chip completed

Recently, the MSA (Multi-Source Agreement) industry alliance for 1.6T optical interfaces was established, announcing that 1.6Tb/s optical modules will become the next hot spot for global competition. However, 1.6Tb/s optical chips have extremely high challenges in terms of speed, integration, packaging technology, etc., and there is no clear and complete solution internationally.

Recently, the National Information Optoelectronics Innovation Center (NOEIC), Pengcheng Laboratory, the National Key Laboratory of Optical Fiber Communication Technology and Network of China Information and Communications Technology Group, and Wuhan Accelink Technologies Co., Ltd. took the lead in completing the joint development and functional verification of a 1.6Tb/s silicon-based optical receiver chip in China, achieving the first leap in my country's silicon photonic chip technology to the Tb/s level.

According to reports, researchers integrated 8-channel high-speed electro-optical modulators and high-speed photodetectors on a single silicon-based optical transmitter chip and a silicon-based optical receiver chip, respectively. Each channel can achieve photoelectric and electro-optical conversion of 200Gb/s PAM4 high-speed signals. Finally, after chip packaging and system transmission testing, the verification of single-chip optical interconnect technology with a capacity of up to 8×200Gb/s was completed. This work refreshed the best level of single-chip optical interconnect rate and interconnect density in China, showing the outstanding advantages of silicon photonics technology such as ultra-high speed, ultra-high density, and high scalability, and providing a reliable optical chip solution for broadband interconnection in the next generation of data centers.

Previously, Intel was the only company in the world to demonstrate a 1.6Tbps photonic engine in 2020. It was designed and manufactured based on Intel's silicon photonics platform and can provide four 400GBase-DR4 interfaces.

NOEIC has been committed to promoting the technological evolution, domestic first production and industrial transformation of high-end optoelectronic chips. In recent years, it has made continuous breakthroughs in ultra-high-speed optical transceiver chip technology, and has developed a series of new ultra-100Gbaud silicon photonic modulators and detectors, which have been published in Nature Communications, IEEE JSSC, ECOC PDP, and ACP PDP, and have been selected as "China's Top Ten Optical Progress" and "China's Top Ten Semiconductor Research Progress", making sufficient technical reserves for Tb/s optical modules.

NOEIC also actively participates in and promotes the formulation of relevant standards, and leads the China Communications Standards Association (CCSA) in the "100GBaud and above high-speed optical transceiver device research" and "800G optical transceiver module: 4×200G" standards, contributing to the formulation of my country's high-speed optical module industry standards. The National Information Optoelectronics Innovation Center will continue to work with domestic superior units to jointly complete related technical verification and industrial transformation, and strive to provide strong support for my country's information optoelectronics industry to speed up and upgrade and quickly occupy the commanding heights of the industry.

The silicon photonics market is growing rapidly, and 400G optical modules have entered commercial use

With the continuous upgrading and evolution of the network topology of data centers, data center optical interconnection solutions are developing towards higher speed, lower power consumption and lower cost. In the future, the traffic of data centers will become larger and more complex, which will inevitably lead to innovation at the technical level. Silicon photonics technology is one of the innovation directions for data center scenarios. With its inherent advantages in material properties and CMOS technology, it can well meet the needs of data centers for high speed, low cost and low power consumption.

According to Yole's report, the silicon photonics market size will have a compound annual growth rate of 44.5% from 2018 to 2024, growing from US$455 million in 2018 to US$4.14 billion in 2024.

At present, silicon photonics technology is applied in the first generation of 4x25G products, such as 100G PSM4 and 100G CWDM4, in the 500m-2km scenario; in the second generation of 1x100G products, it is mainly used in DR1/FR1 and LR1, in the 500m-10Km scenario; in 200G products, the advantages of silicon photonics integration are not very obvious; in 400G products, 400G DR4/DR4+ products have begun to enter the commercial deployment stage. The development of 800G and even 1.6T optical module prototypes and technical standards are being promoted.

According to Intel's silicon photonics industry development plan, the silicon photonics industry has entered a period of rapid development. In 2022, silicon photonics technology will surpass traditional optical modules in terms of peak speed per second, energy consumption, and cost. At present, the process of silicon photonics is difficult and the packaging cost is high, at 1.5~2 US dollars/GB. However, the cost of traditional optical modules is 1+ US dollars/GB, which is difficult to reduce further, while the cost of silicon photonics is expected to drop to 0.3 US dollars/GB in theory, which has a strong cost advantage in large-scale mass production.

American manufacturers dominate the market, and domestic manufacturers have achieved technological breakthroughs

At present, the global silicon photonics industry chain has gradually matured, with representative companies in every link from basic research and development to commercial applications. Among them, American companies represented by Intel, Acacia, Luxtera, Cisco, and Inphi account for the majority of silicon photonics chip and module shipments, becoming the industry leader.

Domestic manufacturers mainly include Huawei, Accelink Technology, Hengtong Optics, Innolight Technology, Broadcom Technology, and Eoptostar, etc. Although they entered the field relatively late and have a relatively small market share, the technological gap between domestic manufacturers and foreign manufacturers has been getting smaller and smaller through rapid technological catch-up in recent years.

As early as February 2020, Huawei released the 800G adjustable ultra-high-speed optical module in London. According to Huawei, this product supports flexible adjustment of 200G-800G rates; the single-fiber capacity reaches 48T, which is 40% higher than the industry's solutions; based on Huawei's channel matching algorithm, the transmission distance is increased by 20% compared with the industry. This product is used in the full range of Huawei OptiXtrans optical transmission products and is an important part of Huawei's top competitiveness in optical networks.

In September 2020, Accelink Technologies also launched an 800G optical module, which adopts OSFP packaging specifications, CWDM4 wavelength division multiplexing, a total of 8 transmit and 8 receive, and uses single-wavelength 106Gbps PAM4 modulation, which can fully meet the 800G application requirements of customers' data centers.

In December 2020, Innolight Technology also launched 800G optical modules, including 800G OSFP and QSFP-DD800 optical module product lines. When answering questions from investors this year, Innolight Technology stated that 800G optical module products have been sent to overseas customers for testing, and it is expected that 800G products will be purchased in batches by overseas customers in 2022.

In June 2021, Hengtong Rockley Technology Co., Ltd. also released an 800G QSFP-DD800 DR8 optical module based on EML technology, using a 7nm DSP with built-in driver and COB structure to achieve 800G QSFP-DD800 DR8 design, with a total power consumption of about 16W. Hengtong Rockley will open early customer evaluation in the second half of this year and plans to achieve mass production in the second half of 2022. Hengtong Rockley also plans to develop 800G optical modules based on silicon photonics in 2022.

At the same time, Chengdu Eoptolink Communication Technology Co., Ltd. released a series of 800G optical modules, including different models based on EML lasers and silicon photonic chips. Its 800G OSFP optical modules have been tested on 800G switches and showed good performance.

With the completion of the joint development and functional verification of the 1.6Tb/s silicon-based optical receiving chip in China, my country has caught up with foreign countries in silicon photonics technology.