Photonic chip based optical frequency comb using soliton induced Cherenkov radiation

TL;DR

This paper demonstrates the generation of a broad, coherent optical frequency comb using soliton-induced Cherenkov radiation in a silicon nitride microresonator, with full phase stabilization, advancing applications in spectroscopy and communications.

Contribution

It introduces a method to generate a broad, phase-stabilized frequency comb via soliton Cherenkov radiation in a planar microresonator, surpassing previous bandwidth limitations.

Findings

Achieved sub-30fs dissipative solitons in silicon nitride microresonators.

Spectral bandwidth broadened to two-thirds of an octave with Cherenkov radiation.

Successfully phase stabilized the generated frequency comb.

Abstract

By continuous wave pumping of a dispersion engineered, planar silicon nitride microresonator, continuously circulating, sub-30fs short temporal dissipative solitons are generated, that correspond to pulses of 6 optical cycles and constitute a coherent optical frequency comb in the spectral domain. Emission of soliton induced Cherenkov radiation caused by higher order dispersion broadens the spectral bandwidth to 2/3 of an octave, sufficient for self referencing, in excellent agreement with recent theoretical predictions and the broadest coherent microresonator frequency comb generated to date. In a further step, this frequency comb is fully phase stabilized. The ability to preserve coherence over a broad spectral bandwidth using soliton induced Cherenkov radiation marks a critical milestone in the development of planar optical frequency combs, enabling on one hand application in e.g. coherent communications, broadband dual comb spectroscopy and Raman spectral imaging, while on the other hand significantly relaxing dispersion requirements for broadband microresonator frequency combs and providing a path for their generation in the visible and UV. Our results underscore the utility and effectiveness of planar microresonator frequency comb technology, that offers the potential to make frequency metrology accessible beyond specialized laboratories.