# Raman Laser Switching Induced by Cascaded Light Scattering

## TL;DR

This paper investigates how cascaded light scattering influences multimode Raman lasers, revealing mode-switching mechanisms and demonstrating control of laser modes via pump power in whispering gallery mode silica lasers.

## Contribution

It introduces a new theoretical model with additional terms to describe intermodal interactions in multimode Raman lasers, explaining the mode-switching phenomenon.

## Key findings

- Cascaded light scattering extends the optical frequency range.
- Mode-switching can be controlled by pump power in whispering gallery mode lasers.
- New coupled-mode equations account for intermodal interactions.

## Abstract

We show that, in multimode Raman lasers, cascaded light scattering (CLS) not only extends the optical frequency range, but could also modulate the laser dynamics. The origin of this phenomenon is based on the fact that many Raman lasing modes are directly correlated through CLS. The coupled-mode equations only describe single-mode cascaded Raman lasers and are insufficient for describing the multimode case. In this work, we introduce additional terms to account for intermodal interaction and, thence, reveal the physical mechanism behind the mode-switching phenomenon. Additionally, mode-switching controlled solely by a single-mode pump in whispering gallery mode (WGM) silica Raman lasers is demonstrated. As the intracavity pump power is increased, laser switching happens between two adjacent WGMs in the same mode family.