Intel Shines Light On Copackaged Optics

Intel’s eight-laser silicon-photonics research chip could be a breakthrough for copackaged optics. It places the laser array on a silicon chip that can eventually be integrated in the package.

Joseph Byrne

Fiber optics have replaced copper wires for ever-shorter distances: from long-haul transmission to regional loops, last-mile connections, and intra-data-center links. Copackaged optics are enabling even switch ICs, processors, and other chips to connect directly to optical fibers. Lighting up these fibers are external lasers. Intel researchers, however, recently demonstrated an eight-wavelength laser array on a silicon chip that they believe can eventually be integrated in the package.

The company’s array emits eight evenly spaced wavelengths of consistent power. The researchers report spacing and power uniformity four times better than standards. Additionally, as the array heats up, the eight frequencies drift in concert, maintaining their spacing. Because the laser source is on silicon and covered with a dielectric layer, it should be more reliable than a standalone laser, which exposes electrodes for power and control and transmits laser light through its encapsulation material. Although Intel has withheld thermal-performance and reliability details, it’s optimistic thanks to its silicon-photonics experience.

To speed up processing, high-performance-computing (HPC) installations and cloud-service providers (CSPs) need faster interconnects that deliver each bit more economically while consuming less energy. As copper interconnects approach fundamental speed, power, density, and cost limits, attention has turned to optics. By obviating an external laser, Intel’s array may accelerate the replacement of copper.