The chip and experimental setup for generating the microcomb. (Credit: Mia Halleröd Palmgren/Yen Strandqvist/Chalmers)

Tiny photonic devices could be used to monitor a person’s health. Researchers have created a microcomb that could bring advanced applications closer to reality. A microcomb is a photonic device capable of generating a myriad of optical frequencies — colors — on a tiny cavity known as microresonator. These colors are uniformly distributed so that the microcomb behaves like a ruler made of light. The device can be used to measure or generate frequencies with extreme precision.

The new kind of microcomb on a chip is based on two microresonators. The new microcomb is a coherent, tunable, and reproducible device with up to 10 times higher net conversion efficiency than the current state of the art.

The researchers are not the first to demonstrate a microcomb on a chip, but they have developed a method that overcomes several well-known limitations in the field. The key factor is the use of two optical cavities — microresonators — instead of one. This arrangement results in the unique physical characteristics.

Placed on a chip, the newly developed microcomb is so small that it would fit on the end of a human hair. The gaps between the teeth of the comb are very wide, which opens great opportunities for both researchers and engineers.

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