Optical combs with a crystalline whispering gallery mode resonator

TL;DR

This paper demonstrates a tunable, monolithic optical frequency comb generator using a crystalline calcium fluoride whispering gallery mode resonator, with potential applications in microwave signal generation.

Contribution

The work introduces a novel, tunable optical comb generator based on crystalline whispering gallery mode resonators, with control over comb spacing and interactions.

Findings

Successful experimental demonstration of a tunable comb generator

Observation of interacting optical combs and hyperparametric oscillation

Potential for generating narrowband microwave signals

Abstract

We report on the experimental demonstration of a tunable monolithic optical frequency comb generator. The device is based on the four-wave mixing in a crystalline calcium fluoride whispering gallery mode resonator. The frequency spacing of the comb is given by an integer number of the free spectral range of the resonator. We select the desired number by tuning the pumping laser frequency with respect to the corresponding resonator mode. We also observe interacting optical combs and high-frequency hyperparametric oscillation, depending on the experimental conditions. A potential application of the comb for generating narrowband frequency microwave signals is demonstrated.