Since 1985, silicon photonics technology has evolved from the original high confinement waveguides to the strategic adoption of CMOS technology, which has established its dominance in the field of transceivers. In the coming years, silicon photonics technology has the potential to expand into a wide range of innovative applications.

Since the beginning of 2023, silicon photonics technology, especially optical computing, optical I/O and a variety of sensing applications, which have been in high demand and have received significant investment. It seems logical that the main technologies in various applications will soon be replaced by optical-based designs and architectures. The giants predict that optics will be necessary and will soon become ubiquitous, while startups are developing new applications through R&D. So, can we expect this prediction to come true anytime soon?

While there are many arguments that photonics must be combined with electronics, the largest market for silicon photonics – datacom (datacom). pluggables) – accounts for only about 12% of data communication transceiver revenue (which is expected to be reached by 2028 30%)。 The semiconductor market is suffering from a prolonged recession, leading to more pragmatic buying behavior for customers. DC operators prefer long-established and low-cost technology solutions. Yole Intelligence's market research shows that silicon photonics technology is not yet the dominant technology, even for data center interconnects within a 500-meter range.

In this context, silicon photonics is still an actively developing technology with a wide range of potential applications, which bodes well for promising opportunities on the horizon. In the next decade, there will be frontrunners, leading to industry consolidation. However, the wide range of applications will ensure that there are plenty of opportunities for expansion and diffusion of the technology.

In its latest Silicon Photonics Technology 2023 report, Yole Group estimates that the silicon photonics PIC market was valued at $2022 million in 6800 and is expected to be 2028 It will exceed $6 million per year, growing at a CAGR of 2022% during 2028-44 (CAGR2022-2028). This growth will be driven primarily by 800G, which is used to increase the capacity of the fiber network High data rate pluggable module push. In addition, predictions of the rapidly growing size of training datasets suggest that the data will need to use light to scale the ML model, using light I/O in the ML server.

Figure 1: Growth forecasts for various silicon photonics applications.

The massive demand for data centers, especially in the fields of artificial intelligence (AI) and machine Xi (ML), is expected to grow over the next decade. Under the traditional processor-centric computing architecture and copper interconnect technology, based on: 3 The state-of-the-art chips of nanotechnology are approaching their physical limits, while the demand for faster data transmission is surging. As a result, silicon photonics technology, which can facilitate high-speed communications, has become a primary focus.

Optical I/O included The architecture simplifies access between compute nodes and memory pools, taking advantage of optical fan-out capabilities to minimize the number of swap hops required to access resources. Broadcom's strategic plan outlines the development trajectory of switching chips, which is expected to start this year 51.2 Tb/s (5nm process node) grows to 2025.102 Tb/s in 4 (3nm process node) and will reach a staggering 2027.204 Tb/s by 8 (2 nanoprocess nodes). This exponential growth will greatly boost the development of silicon photonics technology in network applications, paving the way for significant increases in data capacity in the future. Silicon photonics technology provides a versatile platform for applications with high-volume scalability needs.

The main and most immediate application area of silicon photonics technology is the data center, where Intel dominates (recently sold the business to Jabil?). The second major high-capacity application area is telecommunications, Acacia One example is that it benefits from the stability and excellent performance of silicon processing. A third broad application area includes lidar systems, which have great potential but face challenges in terms of cost and 2D beam scanning. Three-dimensional integration (mounting two chips on the same silicon substrate) is essential for seamless control. Optical gyroscopes require larger chips to mount sensitive rotary sensors, and silicon substrates and silicon nitride waveguides can benefit from this. Quantum computing plays a pivotal role in the ever-evolving field of artificial intelligence and machine Xi. Optical computing is ideal for efficiency-focused tasks and is gaining traction in the industry and is expected to have a significant impact.

Advanced photonic components and their applications in the medical field can transform healthcare, enabling faster and more accurate diagnosis, treatment, and patient monitoring. Regulatory and standardization challenges must be overcome to achieve clinical application. Silicon photonics-based technology has a promising future for medical applications and has great potential in a variety of healthcare and medical fields. The expansion of silicon photonics technology into the visible spectrum shows the potential for future developments, offering a wide range of innovative applications.

The silicon photonics industry landscape is taking shape with a diverse set of players, including: major vertically integrated players (Intel, Cisco, Marvell, Broadcom, Nvidia, IBM etc.); Enterprises actively involved in the silicon photonics industry; start-ups and design companies (AyarLabs, OpenLight, Lightmatter, Lightelligence); research institutes (UCSB, Columbia University, Stanford School of Engineering, MIT, etc.); Foundries (GlobalFoundries, Tower.) Semiconductor, imec, TSMC, etc.); and equipment suppliers (Applied, ASML, Aixtron.) etc.). All of these players have contributed to the substantial growth and diversification of the company.

Intel is a leader in this area and invests heavily in research and development. There are many startups that focus on silicon photonics technology with the aim of bringing innovation to the market. These startups typically focus on specific applications or new technologies, such as high-speed transceivers, optical interconnects, and lidar systems. Universities and research institutes play a vital role in advancing silicon photonics technology, often collaborating with industry partners to develop cutting-edge technologies and share knowledge.

Figure 2: The sheer number of potential applications portends a promising opportunity.

Foundries provide silicon photonics services to help other companies manufacture photonic chips. These foundries often use advanced manufacturing processes such as: CMOS (Complementary Metal-Oxide-Semiconductor) technology to produce these chips. Equipment suppliers provide the tools needed to manufacture silicon photonic devices. The quality and precision of these tools are critical to the production of high-performance photonic components.

The silicon photonics industry is characterized by continuous R&D, strategic partnerships, and collaboration between players to advance the technology. Thanks to the advent of silicon photonic foundries and the growing expertise in the field, the technology is also more accessible to more companies. This technology is a promising area of industry growth due to its ability to increase data transfer speeds, reduce energy consumption, and enable a wide range of applications.

Intel remains the market leader in data communications, with a 61% market share in both shipments and revenue, followed by Cisco, Broadcom, and other smaller companies.

Yole Intelligence expects that as other companies strengthen their product portfolios in the near future and integrate PIC commercialization, Intel will lose its dominant market share. In the telecommunications sector, Cisco (Acacia) holds nearly 50% of the market share, followed by Lumentum (Neophotonics) and Marvell(Inphi)。 Coherent pluggable ZR/ZR+ modules are driving the telecom silicon photonics market.

Figure 3: Intel, Cisco, Marvell... The silicon photonics industry is confident in its future value.

Intel has recently muddied the waters, not only failing to complete the task of building Tower The company's acquisition also spun off its line of pluggable modules based on silicon photonics technology to Jabil. Intel is working hard to regain its leadership in chip production technology, hopefully with Tower The merger of the companies will help accelerate its transformation into a major manufacturer of other chip design companies. The failure of this acquisition will force Intel to focus its Foundry Services (IFS) division's business strategy entirely on leading-edge process technologies. Since technology is the main battleground in the strained economic relationship between China and the United States, it will also send further chills to American companies with close ties to China.

Intel recently made the strategic decision to hand over its production lines to Jabil to optimize operational efficiency, reduce costs, and leverage Jabil's expertise to better serve customers, remain competitive in the market, and increase profitability. Intel is shifting its focus to developing and producing higher-value components, such as processors and compute platforms, that are inextricably linked to upcoming optical interconnect products designed specifically for disaggregated data centers. The company is focusing on silicon photonic components, which are critical for emerging sensing applications such as the automotive industry or medical uses.

Figure 4: Revenue market share of datacom and telecom modules in 2022.

Figure 5: Penetration of laser technology in pluggable modules for data communications, 2021-2028.

Figure 6: Silicon photonics integration roadmap 1992-2030.

Silicon photonics is an advanced technology that requires a high level of manufacturing skills, which are still lacking in China. Chinese companies are still in the prototype or sample stage and need to rely on external cooperation to supply silicon photonic transceivers or optical engines in batches. 2014 Huawei and imec added silicon photonics to their joint research on optical data link technology. Prior to this, Huawei acquired a developer of silicon photonic optical transceivers spun off from imec and Ghent University Caliopa。 Eventually, Huawei's cooperation with imec was terminated, and ASML's EUV lithography system was launched in 2019 was banned from shipping to China. After being added to the U.S. Department of Commerce's Entity List, Huawei continues to conduct research, which is critical to its telecommunications equipment business. China's motivation to invest heavily in silicon photonics technology is strong.

What is the technical approach to silicon photonics?

Despite the drawbacks of silicon as an optical emitter, recent breakthroughs have introduced innovative ways to fabricate active optical components on silicon, which have been mass-produced in just a few years. It is worth noting that silicon has a lower internal quantum efficiency and a direct bandgap The efficiency of III-V materials is close to 100%. It was expected back in the 20s of the 90th century after the success of bonding LEDs (gallium arsenide on GaP) in high-brightness LED applications III-V materials are also very effective at bonding to silicon.

UC Berkeley's partnership with Intel Corporation has played a key role in solving manufacturing problems and enabling high-volume production. The path to silicon photonics appears to be monolithic integration via quantum dots (QDs). traditional InP PICs require five to six regrowth methods, and modulators, lasers, and detectors can be bonded side-by-side and processed together, with inherent advantages. However, due to the size of the III-V substrate, it is much smaller than 300 millimeters, the cost of substrates is not low, which has led to a growing interest in monolithic integration. Therefore, the monolithic integration technology of laser-on-chip provides a promising method for achieving high-density and large-scale silicon photonic integration.

The choice between quantum wells (QWs) and quantum dots in GaA-on-silicon monolithic devices has been a critical issue. After four decades of research, the intrinsic parameters of quantum dot lasers have surpassed QW device for a longer service life. For example, QD gain media have a high tolerance for material defects, so QD lasers can be epitaxically integrated on silicon, and their fast gain response makes them suitable for amplifying high-speed signals.

In addition, the stability of the QD gain medium at high temperatures allows it to operate without cooling, while narrow linewidth lasers, low threshold current densities, internal losses, and constraint factors contribute to low-noise operation. III-V Significant improvements in family/silicon epitaxy technology have pushed QD technology to the forefront of silicon photonics and a wide range of applications. However, it is necessary to popularize this technology to high-capacity, high-performance ones PIC and make it an affordable technology for people to put a lot of effort into it.

The field of silicon photonics is not limited to a single substrate or material. Various material platforms such as thin-film LiNbO3 (TFLN), SiN, BTO, and GaAs and so on, all of which have proven their potential in photonic integration. Among them, silicon-based TFLN is making rapid progress. With its tight schema constraints, TFLN It has proven to be a valuable material for the manufacture of high-speed modulators, comb generators, and various devices. Notably, HyperLight has played a key role in driving this technology to remarkable success.

Waveguides go beyond silicon to encompass a wide range of materials, including lithium niobate compound semiconductors, insulator compound semiconductors (CSOI), silicon nitride, and more. For example, silicon nitride waveguides can support the 980 that operates at very high temperatures Nano tunable lasers, thus opening up extraordinary possibilities.

There is a huge gap in scale between silicon photonics products that are manufactured at 45 nanometers and advanced silicon integrated circuits that work by just a few nanometers. It's worth noting that silicon photonics doesn't require 3 Nanolithography because 45nm technology is more than enough to produce high-performance, high-quality silicon photonics devices. This is very advantageous because it is very cost-effective to use older foundries with lower levels of lithography.

By utilizing 3D bonding technology to connect the PIC to the electronics (lithography for the electronics may reach <> nanometer or higher), we can take advantage of the best of both worlds. Therefore, it does not seem reasonable to integrate photonics and electronics on the same wafer in the same process, as this increases costs and production times. Instead, it is wiser to integrate in three dimensions, combining state-of-the-art electronics with state-of-the-art photonic technology.

Silicon photonics technology has the potential to revolutionize the way data is transmitted and processed, bringing benefits in terms of speed, energy efficiency, and cost-effectiveness. This technology pathway involves a combination of materials science, device engineering, and application development to realize this potential.

Author: Martin Vallo