JOHN WILLIAMSON SILICON PHOTONICS
SILICON PHOTONICS: LEADING LIGHT IN YEARS AHEAD?
Today silicon photonics (SiPho) is looking like a technology whose bigtime has finally arrived, and whose potential in terms of future performance metrics and application areas is huge, writes JohnWilliamson . Reflecting this, market research published by MarketsandMarkets predicts that the global SiPho business could be worth US$4.6 billion in 2027, up from US$1.1 billion in 2021. Meantime, a forecast by Mordor Intelligence PvT Ltd has the value of the overall worldwide photonic IC market at a whopping US$21,649.8 million in 2026.
CMOS AND PHOTONICS: PROMISING BEDFELLOWS
but with SiPho you can because it’s built of the same material. “You can bring optical components much closer to the switch than is the case with regular modules,” he says. “As a result of being able to get closer to the chip, along with co-packaging and things of that nature, you are able to reduce the power consumption by about 30% to 40%.” The densities that can be achieved with SiPho are another plus. “The modulators that we and others build in silicon photonics could be of the order of 20 µm,” comments Arabzadeh. “The modulators that are built using traditional devices would be roughly about two orders of magnitude larger than that.” DATA CENTRE COURT A particular contemporary focus of SiPho application is in intra- and inter-data centre and 5G networking. Here, observes Robert Blum, senior director of Marketing and New Business, Silicon Photonics Division at semiconductor giant Intel, the technology meets increasing demand for data and compute resources, which in turn drives an exponential growth for networking bandwidth in the datacentre. “Silicon photonics came into play when traditional optics could no longer meet the scaling challenges of the largest cloud service providers, which consume millions of optical transceivers a year,” he explains.
“And with wafer scale manufacturing comes not just volume, but also improved quality and reliability – and this is something that our customers value as a key benefit of silicon photonics.” Cost is definitely a big deal in the data centre’s continuing embrace of SiPho. “We see our customers talk about cost advantages versus some of the conventional single mode optics, say the EMLs (Electro-absorption Modulated Lasers) or potentially the DMLs (Directly Modulated Lasers),” confirms Timothy Vang, vice president at Semtech’s Signal Integrity Products Group. “Cost is certainly a must- have, and is seen as a key benefit.” Vang’s company operates on the electronics side of this business, and its chips are used enable SiPho in the data centre. Vang adds that cost is also key in the use of SiPho in 5G networking, and there are similar bit rate and reach requirements to those in the data centre. However, the 5G operating environment is more demanding. “Some of the technical requirements are different,” he states. “In 5G xhaul, for example, the optical modules that are used have to be able to withstand wider temperature ranges than in a data centre. The issue is around the packaging or the implementation in the module. If you have to add a bunch of packaging around that, does that change the cost equation?”
At ground level SiPho has some compelling attractions for optical network designers, builders and users. As instanced by Hamid Arabzadeh, chairman, president and CEO of photonics interconnect solutions provider RANOVUS, traditional legacy optical components and materials may have performance upsides but a couple of not insignificant downsides too. One is to do with complexity of device build. “With optical materials such as indium phosphide (InP) and others, it’s very hard to build small, miniature devices,” Arabzadeh points out. “And the manufacturing processes for them are all custom-based. It’s almost like hand assembling pieces one-by-one.” For optical networking to try to leverage the attributes of the trillion dollar CMOS semiconductor industry, with its mature technology, ecosystem, supply chains and testing capabilities, is something of a no- brainer. “The promise of silicon photonics is to get to the lowest cost possible for having any optical components built,” states Arabzadeh. Power consumption is a ‘table stakes’ issue for SiPho deployments. Arabzadeh reports that conventional switch ICs dissipate anywhere between 300 to 500 W of power, meaning that you cannot bring optical components too close to them,
| ISSUE 28 | Q1 2022
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