Microresonator-Based Comb Generation without an External Laser Source

TL;DR

This paper introduces a fiber-microresonator dual-cavity system that generates broadband optical frequency combs without needing an external laser, simplifying the process and enabling integrated chip-scale sources.

Contribution

A novel dual-cavity architecture that produces broadband combs without external laser pumping, enhancing robustness and integration potential.

Findings

Generates broadband combs (>900 nm) without external laser

Achieves stable combs less susceptible to pump fluctuations

Enables fully integrated chip-scale comb sources

Abstract

Recent developments demonstrate that parametric four-wave mixing (FWM) in high-Q microresonators is a highly promising and effective approach for optical frequency comb generation, with applications including spectroscopy, optical clocks, arbitrary waveform generation, frequency metrology, and astronomical spectrograph calibration. Each of these microresonator platforms utilizes a scheme in which the system is pumped by a single-frequency laser at a cavity resonance. This scheme requires tuning of the pump wavelength into resonance and the generated comb is susceptible to fluctuations in pump power or frequency which can disrupt the soft thermal lock and comb generation. We demonstrate a novel fiber-microresonator dual-cavity architecture that preferentially oscillates at modes of the microresonator due to its high density of states and generates robust and broadband combs (> 900 nm) without an external pump laser. Such a scheme could greatly simplify the comb generation process and allow for a fully-integrated chip-scale source with an on-chip amplifier.