Design of a passively mode-locking whispering gallery mode microaser

TL;DR

This paper numerically investigates the feasibility of passively mode-locking a whispering gallery mode microresonator, highlighting dispersion as a key parameter and providing a general design guideline for ultrahigh repetition rate lasers.

Contribution

It introduces a numerical study of pulsed operation in WGM microresonators with gain and saturable absorption, establishing dispersion as crucial for passive mode-locking and offering a versatile design guideline.

Findings

Dispersion is critical for achieving passive mode-locking.

Numerical simulations demonstrate feasible pulsed operation.

Design guidelines apply broadly to small resonators with gain and SA.

Abstract

Ultrahigh repetition rate lasers will become vital light sources for many future technologies; however, their realization is challenging because the cavity size must be minimized. Whispering-gallery-mode (WGM) microresonators are attractive for this purpose since they allow the strong light-matter interaction usually needed to enable mode-locking. However, the optimum parameter ranges are entirely unknown since no experiments have yet been conducted. Here, we numerically investigate pulsed operation in a toroidal WGM microresonator with gain and saturable absorption (SA) to study the experimental feasibility. We show that dispersion is the key parameter for achieving passive mode-locking in this system. Moreover, the design guideline provided in this work can apply to any small resonators with gain and SA and is not limited to a specific cavity system.