Counter-propagating solitons in microresonators

TL;DR

This paper explores counter-propagating solitons in microresonators, demonstrating independent control of their properties and the ability to generate dual frequency combs with high coherence for advanced optical applications.

Contribution

It introduces the study of counter-propagating solitons in microresonators, showing how their relative phases and repetition rates can be independently controlled and phase-locked.

Findings

Independent control of round-trip times for counter-propagating solitons

Achieving phase and repetition rate locking between soliton streams

Generation of dual-soliton frequency combs with high coherence

Abstract

Solitons occur in many physical systems when a nonlinearity compensates wave dispersion. Their recent formation in microresonators opens a new research direction for nonlinear optical physics and provides a platform for miniaturization of spectroscopy and frequency metrology systems. These microresonator solitons orbit around a closed waveguide path and produce a repetitive output pulse stream at a rate set by the round-trip time. In this work counter-propagating solitons that simultaneously orbit in an opposing sense (clockwise/counter-clockwise) are studied. Despite sharing the same spatial mode family, their round-trip times can be precisely and independently controlled. Furthermore, a state is possible in which both the relative optical phase and relative repetition rates of the distinct soliton streams are locked. This state allows a single resonator to produce dual-soliton frequency-comb streams having different repetition rates, but with high relative coherence useful in both spectroscopy and laser ranging systems.