Silicon photonics is one of the emerging technologies to generate significant research interest due to its potential benefits in optoelectronics applications. The growing trend of miniaturization of electronics devices with rising need for speed and efficiency has resulted in the increasing demand for silicon photonics in optical communications, servers, and data centers.
Silicon photonics has emerged as a disruptive technology to address data bottlenecks inside of systems and between computing components, enhancing power efficiency, improving response times and delivering faster insights from Big Data. Silicon photonics uses photons to detect process and transmit information more efficiently than electrical signals, and yet have low manufacturing costs as a result of using conventional silicon-integrated-circuit processes.
Silicon photonics refers to the application of photonic systems using silicon as an optical medium. The silicon material used in such photonic systems is designed with sub micrometer precision and is deployed into the microphotonic components. Silicon photonics combines technologies such as complementary metal oxide semiconductor (CMOS), micro-electro-mechanical systems (MEMS) and 3D Stacking.
The introduction of 5G technology and growing demand for bandwidth will provide an option for corporations to expand their R&D initiatives in the photonics sector. In 5G connectivity, this modern system will help to channel a large volume of data traffic at a low cost and to transform the radio access network efficiently. With the acceptance of cloud services, there is an increased rate of data traffic, which has directed to a rise in the demand for data centers. The rising demand for high-speed data transmission in data centers is projected to boost the demand for silicon photonics.
Silicon photonics allows transfer of large volumes of data at very high speed between computer chips in servers, large datacenters, and supercomputers, overcoming the limitations of congested data traffic and high-cost traditional interconnects. In addition, features such as low environmental footprint, low heating of components, low operating cost, high optical functions integration, high density of interconnects, low error rate and spectral efficiency are adding value to the silicon photonics products. Yole Développement estimates the 2018 global market for silicon photonics at US$500 million and predicts growth to US$3.5 billion by 2025. The numbers include potential applications, including data centers, 5G, LiDAR, and biosensors.
Katharine Schmidtke, strategic sourcing manager, optical technology at Facebook says, “Silicon photonics can produce integrated designs, with all the required functions placed in one or two chips. Such designs will also be needed in volume, given that a large data centre uses hundred of thousands of optical transceivers, and that requires a high-yielding process. This is a manufacturing model the chip industry excels at, and one that silicon photonics, which uses a CMOS-compatible process, can exploit.”
Schmidtke is upbeat about silicon photonics’ prospects. “Why silicon photonics is attractive is integration; you are reducing the number of components and the bill of materials significantly, and that reduces cost,” she says. “Then there is all the alignment and assembly cost reductions; that is what makes this technology appealing.”
Silicon Photonics technology
After decades of research and development, silicon photonics products have moved to market and into real-world applications in the past couple of years. The technology is particularly attractive in the data center, where intra-center links of hundreds of meters are required as hyperscale facilities come online. The best solution for these is optical fiber. Currently, pluggable transceiver modules are used, but there are cost-, space-, and power-saving advantages to integrating transceivers into the same package as the electronics.
In the past, photonics was fabricated using specialty fabs, often based on Indium Phosphide (InP). “Silicon has allowed companies to access the larger scale of manufacturing,” asserts Radha Nagarajan, CTO for Inphi. “Silicon uses 8-inch or 12-inch wafers (200mm or 300mm), versus a 3-inch or at most 4-inch wafer (100mm) for InP. The scale of manufacturing is different. Silicon also draws upon manufacturing processes, such as implants. These are very commonly used in silicon photonics, but not as common in InP, where etch is used to form certain structures and then you passivate them.”
Most Si photonics technologies are based on SOI technology. Here, a silicon or a silicon nitride layer is sandwiched by two silicon oxide claddings. The core layer (Si or Si3N4) acts as a waveguide, given its refractive index mismatch with silicon oxide (note: an Si layer with 220nm thickness with 5um buried oxide is in general selected).
Silicon-on-insulator processes can be used to form waveguides, modulators, and other optical structures in silicon and take advantage of CMOS’s low cost and scalability. Luxtera’s Welch notes that in addition to being low cost, silicon photonics is incredibly high volume. “If you are using a CMOS foundry, their capacity is unparalleled,” he says. “In the past, slow production has delayed adoption of optical solutions
Another advantage of going to 300mm is that foundries are more likely to be using advanced fabrication technologies. “While you don’t need great lithography for optics, it doesn’t hurt,” says Welch. “The structures are huge compared to transistors, and most optical structures have infinite bandwidth, so they don’t need to scale like you need to scale CMOS to make it faster.”
“The photonics die is generally lower cost to manufacture,” says Chris Cone, product marketing manager in the Custom IC design group of Mentor, a Siemens Business. “They are generated at a lower technology node such as 130 or 65nm, and the photonics dies tend to be larger. This means they can be flip-bonded, with a CMOS die bonded on top of it.
One significant problem remains. The laser itself. “A major issue is the integration of the active optical elements, which are typically compound semiconductor-based lasers,” says Martin Eibelhuber, deputy head of business development for the EV Group. “The performance of these lasers cannot be met by silicon-based devices and thus heterogeneous material integration is required, which is not common to a standard CMOS infrastructure. Direct wafer bonding has proven to be an excellent method of combining different materials — allowing high-quality integration at low costs.
And certain challenges remain. Nagarajan points to a big one. “You need Germanium as a detector, and pure Germanium growth remains a challenge.”
Rockley Photonics CEO Andrew Rickman’s view is that the future of optical connectivity is in-package optics, with optimized silicon photonics and microelectronics dice in the same package rather than on the same die.
“The behavior of photons and electrons is vastly different,” said Rickman. “As a result, the process that is needed to develop the most optimized electrical ICs will be different from the process needed to develop the most optimized photonics ICs. This is why monolithic integration — while it is a seductive idea — can never realize the full potential of silicon photonics. We now have significant innovation in packaging technology, such as 2.5D and 3D wafer-level packaging, that can be used to develop and manufacture the most effective overall solution, and we see this approach lasting for some time.”
Rickman noted that lasers need to be implemented in direct-bandgap (III–V) materials, so all silicon photonics solutions will need multiple dice anyway. Instead of further integration, correct partitioning of the solution onto different dice is key, he said.
“We believe that, ultimately, the optimal solution will monolithically integrate the digital content and the analog front end, while the silicon photonics and lasers remain in separate processes — this is the approach we demonstrated with Topanga,” Rickman said, referring to the company’s demonstrator device from OFC ’18.
Topanga is a 12-port 100G Ethernet switch with all 12 100G transceivers pre-installed. It uses an in-house–designed 1.2-Tb/s Ethernet switch ASIC with Layer 3 routing capability, plus the analog front ends (AFEs) for all 48× 25-Gb/s electrical channels. The ASIC is co-packaged with silicon photonic ICs implementing optical interfaces based on parallel single-mode fiber. The optical power is provided by external laser modules. The PICs are mounted directly adjacent to the CMOS die to minimize the length of the high-speed electrical channels, simplifying their design and reducing power consumption.
A new manufacturing approach to optical transceivers
The multi-$100 billion silicon electronic supply chain has benefited from shared design methodologies, automated wafer manufacturing, shared packaging approaches and common test infrastructure to deliver unparalleled economies of scale for computing and networking equipment. The optical transceiver industry, by comparison, is a cottage industry built on fractured design methodologies, captive wafer manufacturing, proprietary packaging and labour-intensive production that limits economies of scale.
The unique difference to Juniper’s approach is the integratration of all photonic elements of an optical transceiver—most importantly the lasers and the detectors—within a single silicon photonics die. This is achieved by integrating indium phosphide materials into a silicon process flow right on the silicon wafer—Juniper’s core intellectual property—to solve for a fundamental deficiency in existing silicon photonics technologies: the inability to amplify or generate light on chip.
The ability to incorporate all optical components within a single, common silicon die fundamentally changes and simplifies how an optical transceiver can be assembled and tested, dramatically reducing costs. The intellectual property that comprises Juniper’s silicon photonics platform differentiates it from any other silicon photonics platform in the market:
1. At the die level, each of Juniper’s silicon photonics integrated circuits includes an optical loopback switch that allows the transmitter to be directly connected to the receiver. This enables the entire optical circuit to be tested during the manufacturing process using standard electronics-based wafer-level test equipment. Performing these tests before final assembly drastically improves the yield by identifying known good die without test escapes. The native optical loopback switch not only helps improve manufacturing yields, but can also be leveraged to perform in-service diagnostics while the pluggable optic is deployed in a live network, giving operators another tool to troubleshoot network issues remotely.
2. At the “Opto-ASIC” transceiver package level, Juniper’s silicon photonics die is flip-chip-attached alongside other electronic ASICs to form a transceiver on a single, low-cost, ball grid array (BGA) substrate. This provides tremendous flexibility to how and where the transceivers are placed. By utilising standard BGA package sizes, the transceiver package uses mature silicon testing methodologies making it easily adaptable to existing silicon manufacturing processes while maintaining stringent yield levels at high volume, further lowing the total cost to bring silicon photonics optics to market.
3. At the module level, using a fully integrated silicon photonics platform transceiver permits a simplified printed circuit board design that only needs to accommodate the surface mounted transceiver package and DC-DC voltage converters. Fibre connection to the transceiver package is facilitated by a remateable connector that snaps into place with a clip. The resulting module architecture is easy to assemble and is yet another example of engineering simplicity with the silicon photonics platform for further cost reduction.
Juniper’s silicon photonics technology leverages deep expertise in systems integration. This enables the silicon photonics platform packaging, in an optical pluggable transceiver module, to meet all standards-based specifications when used across any routing, switching or security platform. This additional level of compliance verification ensures that the transceiver modules are compliant and fully interoperable with any vendor’s networking equipment deployed today or in the future, allowing customers to deploy Juniper silicon photonics-based transceivers anywhere in their network while enjoying peace of mind of fully interoperable transceivers.
Future applications of silicon photonics
Juniper’s unique silicon photonics technology could also be incorporated into future Juniper packet forwarding engines, along with Penta Silicon and Triton Silicon, providing an entirely new generation of scaling performance at the linecard and system level, to enable petabit-per-sec total system capacity. By combining our silicon photonics technology and our network processors, the sky’s the limit for system level capacity, power consumption and performance.
Juniper’s silicon photonics technology provides an entirely new approach to optics manufacturing that leverages design, wafer manufacturing, packaging and test infrastructure and methodologies from the electronics ecosystem, delivering the most advanced and cost-effective networking products. As new applications are introduced to the market, such as 5G, 8K video and AR/VR, the bandwidth requirements per individual router or switch will reach a point where networking vendors will be forced to re-engineer how these networking elements are architected. Juniper’s fully integrated “Opto-ASIC” transceiver provides a novel approach forward with its ability to densely package electronic and photonic die in a single, low-cost package, and it is completely agnostic to being packaged in existing module form factors (QSFP, QSFP-DD, OSFP, COBO, etc.). While packet processing capabilities of network processor chips keep increasing exponentially, the ability to push that much bandwidth in and out of the network processors electrically is hitting the brick wall of Shannon’s law. There is a clear inflection point approaching us where the only way to increase the throughput of the network processors is to directly integrate photonics on the same package as the network processor.
Silicon Photonics Market worth over $3bn by 2026
The global silicon photonics market share is expected to grow from $1.20 billion in 2021 to $1.49 billion in 2022 at a compound annual growth rate (CAGR) of 24.13%.The market size is expected to reach $3.44 billion in 2026 at a CAGR of 23.23%.
The growth is driven by rising demand for silicon photonics in data centers, reduction in power consumption with use of silicon photonics-based transceivers, and the growing requirement of high bandwidth and high data transfer capabilities. The Global Silicon Photonic Market is expected to reach USD 4.62 Billion by 2027, according to a new report by Emergen Research.
The rapid growth in the usage of smartphones and internet services has led to the increased use of silicon photonics transceivers for telecommunications applications and is anticipated to fuel demand for the silicon photonics market. The government’s influence on the population to shift towards e-banking and internet-based money banking is also expected to drive the silicon photonics market. Moreover, characteristics such as low environmental impact, high interconnectivity capacity, low operating costs, low failure rate, and spectral performance are expected to propel the silicon photonics market demand.
The exceptional ability to transfer in the range of 100 gigabytes per second of data with a low error rate over optical signals is creating growth opportunity for the silicon photonics market. The growing trend of high data transfer over social networking sites and consumer-based applications will generate a massive amount of data daily, favoring the market demand. Moreover, rise in deployment of hyper-scale datacenters to establish a robust infrastructure in the BFSI sector by integrating large number of servers, storage devices, and photonic components will propel the market growth. Hyperscale Data Centers (HDCs) prefer photonic devices due to their ability to handle large data, high security, and scalability, driving the market size.
Silicon photonics has a higher reflective index compared to other semiconductors, which is one of the major challenges faced by manufacturers to achieve miniaturized fabrication of components. High initial cost coupled with thermal effect issues that hamper the performance of the device will further restrict the silicon photonics market growth. Furthermore, the presence of low-cost substitutes, such as Vertical Cavity Surface Emitting Laser (VCSEL), will further limit the adoption of photonics devices. However, the increasing risk of thermal effect, which may affect the performance of the systems, and the complexity of On-Chip Laser integration are expected to hinder the market growth in the forecast timeframe.
Silicon photonics has been under development for years. However now, this technology is being pushed hard by large webcom companies like Facebook and Microsoft. “Silicon photonics has reached the tipping point that precedes massive growth,” comments Dr Eric Mounier from Yole.“Indeed we estimate, the packaged silicon photonics transceiver market will be worth US$6 billion in 10 years.” Yole Développement (Yole), the “More than Moore” market research and strategy consulting company has released the technology & market analysis titled Silicon Photonics for datacenters and other applications.
The North America silicon photonics market revenue will register a substantial CAGR of 30% from 2019 to 2026. The growth is majorly attributed to rising funding series from the government to encourage photonics-based projects in the region. Market players are involved in several research & development activities to increase Silicon-based photonics technology adoption in various industries. Companies are investing heavily in new capabilities and implementing several merger & acquisition strategies to strengthen their presence.
North America has the largest market for multiplexer wavelength filters, and silicon optical modulators, become a lucrative destination for businesses to start the silicon photonics market due to government encouragement. The Asia Pacific is expected to grow significantly due to an increasing population, urbanization, and rising demand for data transmission.
The silicon photonics market in APAC is expected to grow at the highest CAGR between 2018 and 2023. China, Japan, and South Korea are the major contributors to the market in APAC. The increasing requirement of high-speed data communication and the increasing focus of international and domestic IT companies on big data analytics and cloud-based services in the region would fuel the growth of the silicon photonics market. Increasing investments toward the development of silicon photonics products and domestic players on the silicon photonics market, and increasing R&D activities in the region also fuel the market growth.
The silicon photonics market, by application, is segmented into telecommunications, data communication, commercial video, metrology and sensors, consumer electronics, medical, military, robotics, and others. The major reason for the growth of silicon photonics technology is the increasing demand for high-speed data transfer, data integration and small factor form in various applications such as data communication, telecommunication and consumer electronics.
As a result of developments in remote diagnostics and remote surgery in the medical and healthcare industries, the demand for silicon photonics is expected to expand in the healthcare industry. A rise in global internet penetration and growth in the number of smartphones are propelling the market growth. Silicon-based photonic devices increase the bandwidth capacity with low-power consumption, improving telecom services with long-range communication. Furthermore, the rising trend of work from home due to COVID-19 pandemic has resulted in the rising need for high-speed data transmission with large bandwidth over the internet. To support these bandwidth levels, the telecommunication sector will increase the deployment of Silicon photonics as an emerging technology solution in the market.
The telecommunication industry is anticipated to witness the highest market growth rate through the forecast period due to the implementation of 5G technologies to deliver higher bandwidth and high-speed data transfer. 5G network is in the initial phase of deployment, and COVID-19 has delayed the deployment of 5G network, which, in turn, will affect the growth of the silicon photonics market throughout the FY 2020–2021.
The variable optical attenuators segment is expected to witness constant growth in the coming years due to the rising adoption of broadband internet in developing countries, testing and deployment of 5G in the telecommunications industry, and escalating demand for high-speed internet connectivity in commercial and industrial applications. For instance, several US-based telecommunication companies such as AT&T and T-Mobile already rolled out 5G networks in 2019, which provide faster data transfer and communication across multiple cities and towns of the US.
An optical modulator is a device that can modulate or alter the fundamental characteristics of a light beam that propagates in free space or in an optical waveguide. Modulators change/modify properties such as optical power or phase of light beams. An optical modulator can alter different beam parameters; optical modulators can be categorized into amplitude, phase, and polarization modulators. These are mainly used to manipulate the property of light of an optical beam, e.g., a laser beam. Silicon optical modulators are divided into absorptive and refractive modulators. Owing to the increasing demand for high-speed optical networks, the market for silicon modulators is likely to witness a high growth rate during 2021–2027.
Data center and high-performance computing held the largest share of the silicon photonics market in 2017. Data centers are experiencing an exponential increase in data traffic due to the rise of cloud computing and several emerging web applications. To manage this network load, large data centers are required with thousands of servers interconnected with high-bandwidth switches.
The use of silicon photonics technology in active optical cables, transceivers, multiplexers, lasers, and other devices have increased the scope of the silicon photonics market for different applications.
The optical cables segment in the silicon photonics market is projected to grow at a significant rate of 35% till 2026 due to their applications in high-performance computing, cloud, and storage. It can transfer high data rates over long distances while ensuring high-performance and optimum signal integrity, as well as the capability to consume low power. Optical cables have lucrative advantages over traditional optical modules due to their low-cost structure and provide streamline installation in telecom infrastructures and data centers.
Recent technological advancements in data processing using scalable host controller interface design are gaining traction to provide new solutions in cloud and enterprise infrastructures. The cloud and enterprise systems are driving growth opportunities owing to a high volume of data generated in the global market. Improvements in data transferring speed through Active Optical Cables (AOC) and an increase in demand for high storage memory systems have triggered the market growth.
The Silicon Photonics Market for transceivers is expected to grow at the highest CAGR between 2018 and 2023. Transceivers are used in a variety of applications, such as high-performance computing, owing to high demand for high-speed data transmission in data centers.
The laser segment is expected to dominate the market with a significant share of 33.7% over the forecast timeframe due to the increasing development of tunable lasers and hybrid silicon. The waveguide segment is projected to grow substantially owing to the wide applications of this component in the telecommunication sector.
The passive photonics filters segment held a market share of 25% in 2019 owing to increasing investment in the deployment of the upcoming 5G network. The introduction of 5G mobile communication technology will lead to increasing demand for smartphones and other interconnected devices, in turn, increasing growth opportunities for silicon photonics components. Filters are heavily deployed in 5G infrastructure and mobile phones to mitigate the radio frequency of the network.
The rising proliferation of Datacenter Interconnect (DCI) technology to connect two or more datacenters over short, medium, and long-range distance is creating high growth opportunities for the silicon photonics market. The DCI technology uses passive optical filters to manage the wavelength and remove distortion in optical signals. The passive filter uses Wavelength Division Multiplexing (WDM) phenomena for transferring high data rates over a long distance through photonics-based technology. The growing adoption of silicon photonic components for data transfer over current technology is anticipated to drive the market size.
Many tier 1 players are entering into this market-for instance, Intel (US) started its research in silicon photonics in the last decade and launched its first 10 Gbps product in partnership with Luxtera. Intel announced volume production of its first silicon photonic device in 2016 and has since added two more products. The three devices are 100G and 400G transceivers for data center applications and a 100G transceiver with extended temperature range targeting 5G fronthaul. The 5G device is a CWDM4 QSFP28 coarse wavelength-division multiplexing, quad small-form-factor pluggable transceiver supporting 10-km links over single-mode fiber at operating temperatures of –40°C to 85°C. Intel’s 100G CWDM4 and QSFP28 optical transceiver has higher bandwidth capabilities and can support speeds up to 100 Gbps.
Active components include optical modulators, photo detectors, wavelength-division multiplexing filters, switches, and lasers integrated within a single device, providing a smaller form factor with the help of silicon photonics. Optical transceiver volumes used by data centres are growing, and growing fast, and will account for half the industry’s demand for Ethernet transceivers by 2020, according to LightCounting Market Research.
“The architecture has changed, from copper cables between the antenna and the remote station, then optical connections to the metro network, [and] now an RF front end with the antenna connected directly to an optical transceiver … and the data rates are much higher,” said Sicoya CEO Sven Otte. “The majority of these connections are point-to-point, single-channel. Sometimes in metropolitan areas, there are multiple antennas on one mast, and in that case, you need a CWDM transceiver to use one fiber only to the remote station.”
Sicoya products include the 100G transceiver line that launched in 2017 and a line of three 400G transceivers that debuted last month at OFC ’19. The 400G models are currently in qualification and are due to start shipping in the second half of the year. There is also a product designed for 5G infrastructure: a 28G single-channel, single-mode transceiver, with a CWDM version in the works.
Otte highlighted several advantages that silicon photonics can offer 5G infrastructure. Silicon photonic chips are inherently insensitive to temperature, so they can survive the often extreme environmental conditions experienced by 5G deployments, from snowstorms to deserts. The technology is easily scalable, an obvious benefit for 5G, and it offers the ability to future-proof designs. There is also the matter of cost. For the traditional, discrete solution, the packaging accounts for a huge portion of the cost. Silicon photonics chips, with laser die attached, can use electronics packaging, which requires minimal process steps by comparison.
Otte was clear that 5G infrastructure isn’t a future application — it’s happening now. “We are ramping our product for the 5G market; it will be rolled out into the field by the end of the year by one of our Chinese telecom customers,” he said. “5G is one of the largest-volume drivers that we see in the market … For us, volume-wise, 5G is bigger than the data center market by a factor of two or three.”
The major players in the silicon photonics market are Acacia (Switzerland), Color Chip, Fujitsu, Cisco Systems (US), Intel (US), Hamamatsu Photonics, MACOM Technology (US), Finisar (US), STMicroelectronics (Switzerland) GlobalFoundries (US), NeoPhotonics (US), IBM (US), Juniper (US), InPhi (US), II-VI (US), IBM (US), STMicroelectronics (Switzerland), Rockley Photonics (US), Mellanox Technologies (Israel), Sicoya (Germany), Lumentum Operations (US), RANOVUS (Canada), Broadcom (US), Hamamatsu Photonics (Japan), Molex (US), Fujitsu (Japan), Chiral Photonics (US), EFFECT Photonics (Netherlands), AIO Core (Japan), NKTPhotonics (Denmark), IPG Photonics (US), DAS Photonics (Spain) and TDK Corporations ( Japan)
In September 2021, NeoPhotonics Corp, a US-based designer and manufacturer of silicon photonics, launched a CFP2-DCO module with 0dBm output power for ROADM-based metro, regional, and long-haul networks. This product has a transmission speed of 400 Gbps over a range of 1,500 km. This system contains an ultra-pure Nano tunable laser, as well as a Class 40 coherent receiver and coherent driver modulator that can transmit data at up to 67 Gbaud. This allows for longer-distance transmission while also improving the receiver optical signal-to-noise ratio (rOSNR).
Cisco Systems Inc.
The company offers silicon photonics under the brand names Cisco 400 Gigabit Modules, Cisco 100 Gigabit Modules, Cisco 40 Gigabit Modules, Cisco 25 Gigabit Modules, Cisco 10 Gigabit Modules, Cisco One Gigabit Modules, and Cisco 100 Megabit Modules.
GLOBALFOUNDRIES US Inc.
The company offers solutions to markets including mobility, automotive, computing and wired connectivity, consumer IOT, and industrial. The company offers silicon photonics under the GF SiPh portfolio.
II VI Inc.
The company manufactures and markets optical and electro-optical components and materials. The company offers 40G and 50G Silicon Photonics.
The GAFAM and BAT companies — Google, Apple, Facebook, Amazon, Microsoft, and, in China, Baidu, Alibaba, and Tencent — are pushing silicon photonics hard because of the technology’s inherent advantages over legacy optics, said Yole’s Mounier. Meanwhile, foundries are aiming to offer a generic process to fabless silicon photonics customers.
“It is true that more and more foundries are interested in silicon photonics, whether that’s large foundries such as STM, GlobalFoundries, and TSMC or MEMS [microelectromechanical system] foundries that diversify, such as Silex Microsystems, APM, and VTT,” Mounier said. “GlobalFoundries already has many partnerships with silicon photonics fabless companies … silicon photonics will add more business by leveraging GlobalFoundries’ existing semiconductor manufacturing platforms.”
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