Differential phase reconstruction of microcombs

TL;DR

This paper introduces a highly sensitive and broadband linear heterodyne method with electro-optic downconversion for measuring the spectral phase of microcombs, providing new insights into their nonlinear dynamics.

Contribution

It presents a novel differential phase measurement technique that overcomes previous experimental challenges in microcomb spectral phase characterization.

Findings

Achieved sensitivity of -50 dBm in phase measurements

Covered spectral bandwidth greater than 110 nm in telecom range

Validated with measurements on single cavity and photonic molecule microcombs

Abstract

Measuring microcombs in amplitude and phase provides unique insight into the nonlinear cavity dynamics but spectral phase measurements are experimentally challenging. Here, we report a linear heterodyne technique assisted by electro-optic downconversion that enables differential phase measurement of such spectra with unprecedented sensitivity (-50 dBm) and bandwidth coverage (> 110 nm in the telecommunications range). We validate the technique with a series of measurements, including single cavity and photonic molecule microcombs.