Brillouin-Kerr soliton frequency combs in an optical microresonator

TL;DR

This paper demonstrates a novel method to generate stable, narrow-linewidth soliton Kerr microcombs in an optical microresonator using a Brillouin laser as a low-noise pump, enabling practical high-performance applications.

Contribution

It introduces a new intracavity Brillouin laser pumping scheme to access soliton states with enhanced stability and low noise in Kerr microcombs.

Findings

Achieved narrow-linewidth comb lines and stable repetition rate.

Generated low-noise microwave signals with phase noise levels of -147 dBc/Hz at 1 MHz.

Demonstrated easy operation with broad linewidth diode lasers.

Abstract

By generating a Brillouin laser in an optical microresonator, we realize a soliton Kerr microcomb through exciting the Kerr frequency comb using the generated Brillouin laser in the same cavity. The intracavity Brillouin laser pumping scheme enables us to access the soliton states with a blue-detuned input pump. Due to the ultra-narrow linewidth and the low-noise properties of the generated Brillouin laser, the observed soliton microcomb exhibits narrow-linewidth comb lines and stable repetition rate even by using a diode laser with relatively broad linewidth. Also, we demonstrate a low-noise microwave signal with phase noise levels of -24 dBc/Hz at 10 Hz, -111 dBc/Hz at 10 kHz, and -147 dBc/Hz at 1 MHz offsets for a 11.14 GHz carrier with only a free-running input pump. The easy operation of the Brillouin-Kerr soliton microcomb with excellent performance makes our scheme promising for practical applications.