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Integrated Silicon Photonics Driving High-Speed Optical Interconnects

Co-packaged optical and silicon parts make possible higher speed and bandwidth needed for next-generation lasers and other optical electronics.

Spencer Chin

March 29, 2022

3 Min Read
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Rapid progress in integrating photonics circuits onto silicon is enabling electronics manufacturers to meet high-speed transceiver needs.Image courtesy of Wikipedia

The concept of integrating photonics circuits on silicon has challenged engineers since the 1980s, but the industry is now making real progress toward getting this technology into production, according to John Bowers, Fred Kavli Chair of Nanotechnology, University of California, Santa Barbara.

Bowers will deliver one of three keynote presentations at DesignCon, taking place at the Santa Clara Convention Center in Sunnyvale, April 5th through 7th.  His presentation on Tuesday April 5, titled “Progress Enabled; The Convergence of Photonic & Electronic ICs,” will discuss the trend toward co-packaged optical and silicon products. Bowers, in an interview with DesignNews last week, said integrating photonics with electronics has helped increase the speed and aggregate bandwidth of silicon photonics-based assemblies.

Rapid progress in electronics has resulted in state-of-the-art chips including switches having many tens of billions of transistors. However, the electronic system performance is often limited by the input/output (I/O) and the power required to drive connections at a speed of tens of Gbps. For Bowers and other researchers, the convergence of progress in silicon photonics and electronics means that co-packaged silicon photonics and electronics propel further innovation in both areas.

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“It was the holy grail for many years,” Bowers said. “It took until the mid-2000 decade to be able to finally make lasers on silicon.” He added that some of the early challenges were achieving low defect density and being able to reliably establish and qualify the production of silicon substrates with photonics circuits in CMOS fabs.

For the past 15 years, Bowers has been involved in research efforts to integrate silicon and photonics. In his current role at the University of California, Bowers oversees work both in laboratory research as well as applied research efforts for applications such as communications.

Photonics Evolution

PICs (Photonics ICs) have evolved from pluggable transceivers at the periphery of the board to co-packaged optics and electronics, and then to 3D integrated PICs and electrical integrated circuits. This trend is enabling lasers, modulators, and photodetectors to achieve performance levels needed for next-generation products.

The timing could not be better given the increased demands for light-based signal transmission. Whether it be LiDAR, gyroscopes, spectrometers, or other devices, the convergence of photonics and silicon is making possible the development of devices able to operate at speeds anywhere from 100 gigabits/sec into terabits per second range, with products now in mass production.

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Once engineers solved the challenges of qualifying silicon production for photonics circuits, the ability to mass-produce transceivers and other photonics products on silicon took off, Bowers noted. Materials such as InP (Indium Phosphide) are not as practical for mass-produced photonics parts. “These (InP) wafers have traditionally been small, and silicon has better thermal conductivity than InP. With CMOS silicon fabs, you can scale up production very rapidly,” Bowers added.

The shift toward integrated photonics is not only evident at traditional semiconductor giants such as Intel, but also at communications companies.“ A few years ago, no one at Broadcomm worked in optics, but now they have an optical systems division working on optical components.”

Bowers sees more opportunities for co-packaged optical and silicon products in the future. “You will eventually need optical interfaces on high-bandwidth memory chips and hopefully see those products within the next decade. He also expects optical devices to see further advances in efficiency and voltage losses.

Spencer Chin is a Senior Editor for Design News covering the electronics beat. He has many years of experience covering developments in components, semiconductors, subsystems, power, and other facets of electronics from both a business/supply-chain and technology perspective. He can be reached at [email protected].

About the Author(s)

Spencer Chin

Senior Editor, Design News

Spencer Chin is a Senior Editor with Design News, covering the electronics beat.

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