Powerful and precise multi-color lasers now fit on a single chip

by Grant Currin, Columbia University School of Engineering and Applied Science

edited by Sadie Harley, reviewed by Robert Egan

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A few years ago, researchers in Michal Lipson's lab noticed something remarkable. They were working on a project to improve LiDAR, a technology that uses lightwaves to measure distance. The lab was designing high-power chips that could produce brighter beams of light.

"As we sent more and more power through the chip, we noticed that it was creating what we call a frequency comb," says Andres Gil-Molina, a former postdoctoral researcher in Lipson's lab.

A frequency comb is a special type of light that contains many colors lined up next to each other in an orderly pattern, kind of like a rainbow. Dozens of colors—or frequencies of light—shine brightly, while the gaps between them remain dark.

When you look at a frequency comb on a spectrogram, these bright frequencies appear as spikes, or teeth on a comb. This offers the tremendous opportunity of sending dozens of streams of data simultaneously. Because the different colors of light don't interfere with each other, each tooth acts as its own channel.

Today, creating a powerful frequency comb requires large and expensive lasers and amplifiers. In their new paper in Nature Photonics, Lipson, Eugene Higgins Professor of Electrical Engineering and professor of Applied Physics, and her collaborators show how to do the same thing on a single chip.

"Data centers have created tremendous demand for powerful and efficient sources of light that contain many wavelengths," says Gil-Molina, who is now a principal engineer at Xscape Photonics.

Source: HackerNews (https://news.ycombinator.com/item?id=45700078)