Silicon photonic chips can emit light on their own, assisting the development of optical communications and CPO

Columbia University's Michal Lipson's team recently published the latest research in "Nature Photonics" and successfully implemented a high-power "frequency comb" light source on a silicon photonic chip. This technology can produce dozens of wavelengths of light with a single laser at the same time, replacing the traditional optical module design that requires multiple lasers, bringing new breakthroughs in high-speed optical communication between AI and data centers.

High-power laser "purifies" multi-wavelength light sources

Although current silicon photonic chips can integrate optical waveguides, modulators and detectors (such as the current CPO architecture), they still have to rely on external lasers for light supply and require different wavelengths. The key to the Lipson team this time is to be able to generate stable multi-wavelength light sources directly on the chip.

Researchers use multimode laser diodes as high-power light sources. Although this type of laser is extremely bright, the output light is usually messy. The team therefore designed a "locking mechanism" to make the output light beam more stable and purer, and reshaped it through the silicon photonic structure to make the light have higher stability and high coherence.

After this layer of "purification", the nonlinear optical effect within the chip will further split a single strong light into multiple evenly spaced wavelengths, forming a so-called "frequency comb" structure. The final result is a micro light source with both high power and high stability. It only needs one laser to output multi-channel light, is smaller and more efficient.

Paving the way for data center and AI optical interconnects

As artificial intelligence and high-speed computing increase the power demand of data centers, optical interconnects are becoming the key to reducing power consumption and increasing transmission speeds. In the past, an optical module often required more than ten lasers, resulting in high cost and heavy heat dissipation burden. Lipson's team's new design can replace an entire row of laser modules with a single chip and can be applied to the miniaturization of CPO (Co-Packaged Optics) packaging and server optical communication modules in the future.

The research team pointed out that in addition to its application in data centers, this technology can also promote the development of new optical devices such as spectrometers, quantum sensing and LiDAR. As silicon photonics technology further integrates light sources, transmission and computing functions, the industry is moving towards a new stage of higher energy efficiency and higher integration.

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