Spectral Sidebands and Multi-Pulse Formation in Passively Mode Locked Lasers

TL;DR

This paper provides a detailed theoretical and experimental analysis of spectral sidebands in passively mode locked lasers, revealing their role in pulse formation, multi-pulse interactions, and cavity inhomogeneities.

Contribution

It offers an explicit calculation of sideband characteristics and links spectral features to multi-pulse dynamics in mode locked lasers.

Findings

Spectral sidebands are explicitly characterized in amplitude, frequency, and shape.

Experimental results in fiber lasers confirm the theoretical predictions.

Sidebands influence inter-pulse interactions and are related to pulse spacing.

Abstract

Pulse formation in passively mode locked lasers is often accompanied with dispersive waves that form of spectral sidebands due to spatial inhomogoneities in the laser cavity. Here we present an explicit calculation of the amplitude, frequency, and precise shape of the sidebands accompanying a soliton-like pulse. We then extend the study to the global steady state of mode locked laser with a variable number of pulses, and present experimental results in a mode locked fiber laser that confirm the theory. The strong correlation between the temporal width of the sidebands and the measured spacing between the pulses in multipulse operation suggests that the sidebands have an important role in the inter-pulse interaction.