Unveiling the Dynamics of Optical Frequency Combs from Phase-Amplitude Correlations

TL;DR

This paper investigates the noise dynamics of an optical frequency comb generated by a mode-locked laser, using advanced detection techniques to analyze amplitude and phase noise correlations across multiple channels.

Contribution

It introduces a spectrally resolved measurement method to decompose noise into significant modes and links noise correlations to laser cavity dispersion effects.

Findings

Noise modes are identified and characterized.

Amplitude-phase noise correlations are measured.

A model explains noise origins related to cavity dispersion.

Abstract

The noise dynamics of an Optical Frequency Comb (OFC) based on a mode-locked Ti-Sapphire laser is analyzed in terms of noise modes. A spectrally resolved multipixel homodyne detection enables the simultaneous measurement of the amplitude and phase noises of several optical frequency channels, from which the covariance matrices of the amplitude and phase quadratures of the laser field are calculated. The decomposition of these matrices into the four most significant time/frequency modes of the field enables the tracking of the origin of the noises and the correlations between the noise modes. In particular, the correlations between the amplitude and phase noises are measured. These measurements are well reproduced by a model taking into account the correlations between the CEO phase noise and the amplitude noise induced by the group velocity dispersion of the laser cavity.