Researchers Develop New Chip-Scale Optical Frequency Combs

Breakthrough could miniaturize optical platforms like spectroscopic sensors or communication systems.

Published on Feb. 28, 2026

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Applied physicists at the Harvard John A. Paulson School of Engineering and Applied Sciences have discovered a new way to generate ultra-precise, evenly spaced "combs" of laser light on a photonic chip. This breakthrough could lead to the miniaturization of optical platforms like spectroscopic sensors or communication systems.

Why it matters

Optical frequency combs are laser sources whose colors are evenly spaced, like the teeth of a comb. They underpin many modern technologies requiring precision measurement, from atomic clocks to high-speed telecommunications. The researchers' work establishes lithium-niobate as a uniquely powerful platform to make high-efficiency microcombs and high-speed electro-optical control that coexist on the same chip.

The details

The researchers developed a new, rotated racetrack-like resonator design that could suppress the Raman effect in lithium niobate, allowing them to produce a class of microcombs called solitons. In the new paper, they used the same design strategy to produce yet another type of frequency comb, called a normal dispersion Kerr microcomb - the first such microcomb ever created on an X-cut lithium niobate chip. They also discovered a new hybrid microcomb that leverages the Raman effect, providing another way to generate frequency combs in spectral bands that are otherwise hard to reach.

  • The research was published in Science Advances in 2026.

The players

Marko Lončar

The Tiantsai Lin Professor of Electrical Engineering and Applied Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the lead researcher on this project.

Yunxiang Song

A graduate student in Quantum Science and Engineering at SEAS and the first author on the paper.

University of Auckland

Researchers at the University of Auckland collaborated on the theoretical modeling and simulations for the newly observed hybrid microcomb.

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What they’re saying

“This work shows that normal dispersion combs can be implemented in technologically relevant thin-film lithium-niobate platform that features strong electro-optic modulation. That's what you want for the next generation of microcomb-driven photonic systems.”

— Marko Lončar, The Tiantsai Lin Professor of Electrical Engineering and Applied Physics at SEAS (Science Advances)

“A broader, coherent frequency comb that leverages the Raman effect -- rather than being limited by it, as common wisdom suggests -- may be useful for covering spectral ranges that are nominally hard to generate combs in.”

— Yunxiang Song, Graduate student in Quantum Science and Engineering at SEAS (Science Advances)

What’s next

The researchers plan to further develop their chip-scale optical frequency comb technology and explore its potential applications in areas such as spectroscopy and high-speed telecommunications.

The takeaway

This breakthrough in chip-scale optical frequency comb generation on a lithium-niobate platform represents a significant advancement in the miniaturization of optical technologies, paving the way for more compact and efficient spectroscopic sensors, communication systems, and other precision measurement devices.