In a recent article in the journal Nature Photonics, eight researchers at Chalmers University of Technology, Sweden, described a new kind of microcomb on a chip, based on two micro resonators. The microcomb is a coherent, tuneable and reproducible device with up to ten times higher net conversion efficiency than the current state of the art.
Since almost any measurement can be linked to frequency, the microcombs offer a wide range of potential applications. They could, for example, radically decrease the power consumption in optical communication systems, with tens of lasers being replaced by a single chip-scale microcomb in data centre interconnects. They could also be used in lidar for autonomous driving vehicles, for measuring distances.
The Chalmers 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 – micro resonators – 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.
A microcomb is a photonic device capable of generating a myriad of optical frequencies – colours – on a tiny cavity known as micro resonator. These colours are uniformly distributed so the microcomb behaves like a ‘ruler made of light’. The device can be used to measure or generate frequencies with extreme precision.
“The reason why the results are important is that they represent a unique combination of characteristics, in terms of efficiency, low-power operation, and control, that are unprecedented in the field,” says Óskar Bjarki Helgason (pictured), a PhD student at the Department of Microtechnology and Nanoscience at Chalmers, and first author of the new article.
For more information, visit www.chalmers.se