Intrinsic Amplitude-Noise Suppression in Fiber Lasers Mode-locked with Nonlinear Amplifying Loop Mirrors

TL;DR

This paper studies how nonlinear amplifying loop mirrors in fiber lasers inherently suppress amplitude noise, leading to reduced intensity fluctuations, with experimental and simulation evidence showing up to 4 dB noise reduction.

Contribution

It demonstrates the intrinsic amplitude-noise suppression mechanism in fiber lasers mode-locked with nonlinear amplifying loop mirrors, supported by experimental and simulation results.

Findings

Amplitude noise reduced by up to 4 dB in certain steady-states

Detected differences in relative intensity noise at output ports

Systematic measurements confirm noise suppression mechanism

Abstract

In this work, we investigate the steady-states of a fiber lasers mode-locked with a nonlinear amplifying loop-mirror that has an inherent amplitude noise-suppression mechanism. Due to the interaction of the sinusoidal transmission function with the fluctuating intracavity pulse amplitude we show that this mechanism may lead to a detectable difference in relative intensity noise at the reflected and transmitted output port under specific preconditions. We present systematic intensity noise measurements with a nonlinear fiber-based system that replicates a single roundtrip in the laser cavity. Experimental results and simulations clearly show a reduction of the intracavity amplitude fluctuations up to 4 dB for certain steady-states.