Continuous scanning of a dissipative Kerr-microresonator soliton comb for broadband, high resolution spectroscopy

TL;DR

This paper demonstrates a method to continuously scan a dissipative Kerr-microresonator soliton comb's modes across nearly the entire free spectral range, enabling broadband, high-resolution spectroscopy on a chip-scale device.

Contribution

It introduces a technique combining PDH locking and microheater control to scan soliton comb modes without losing soliton stability, covering tens of THz bandwidth.

Findings

Achieved continuous mode scanning across nearly full FSR

Resolved spectral features as narrow as 5 MHz

Enabled broadband spectroscopy with a single chip-scale comb

Abstract

Dissipative Kerr-microresonator soliton combs (hereafter called soliton combs) are promising to realize chip scale integration of full soliton comb systems providing high precision, broad spectral coverage and a coherent link to the micro/mm/THz domain with diverse applications coming on line all the time. However, the large soliton comb spacing hampers some applications. For example, for spectroscopic applications, there are simply not enough comb lines available to sufficiently cover almost any relevant absorption features. Here, we overcome this limitation by scanning the comb mode spacing by employing PDH locking and a microheater on the microresonator, showing continuous scanning of the soliton comb modes across nearly the full FSR of the microresonator without losing soliton operation, while spectral features with a bandwidth of as small of 5 MHz are resolved. Thus, comb mode scanning allows to cover the whole comb mode spectrum of tens of THz bandwidth with only one chip-scale comb.