# First insight into the regime transition dynamics of mode-locked fibre lasers

## TL;DR

This paper presents the first detailed observation and analysis of the regime transition dynamics in mode-locked fibre lasers, revealing complex processes from noise to stable mode-locking.

## Contribution

It introduces a real-time programmable fibre laser enabling direct observation of regime transitions, providing new insights into laser dynamics.

## Key findings

- Observed transition dynamics among noise, Q-switching, and mode-locking regimes.
- Analyzed the temporal and spectral characteristics of regime changes.
- Enhanced understanding of the complex nonlinear processes in mode-locked lasers.

## Abstract

Mode-locked lasers exhibit complex nonlinear dynamics. Precise observation of these dynamics will aid in understanding of the underlying physics and provide new insights for laser design and applications. The starting dynamics, from initial noise fluctuations to the mode-locking regime, have previously been observed directly by time-stretched transform-based real-time spectroscopy. However, the regime transition dynamics, which are essential processes in mode-locked lasers, have not yet been resolved because regime transition process tracking is very challenging. Here we demonstrate the first insight into the regime transition dynamics enabled by our design of a real-time programmable mode-locked fibre laser, in which different operating regimes can be achieved and switched automatically. The regime transition dynamics among initial noise fluctuations, Q-switching, fundamental mode-locking and harmonic mode-locking regimes have been observed and thoroughly analysed by both temporal and spectral means. These findings will enrich our understanding of the complex dynamics inside mode-locked lasers.

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Source: https://tomesphere.com/paper/1905.01604