Nonlinear Fiber System for Shot-noise Limited Intensity Noise Suppression and Amplification

TL;DR

This paper introduces a nonlinear fiber system that achieves shot-noise limited intensity noise suppression and amplification of optical signals through polarization-based nonlinear phase shifts and a sinusoidal transmission function.

Contribution

It presents a novel all-optical method combining nonlinear phase shifts and a transmission function for tunable noise reduction and amplification in fiber systems.

Findings

Noise spectral density suppressed by up to ~20 dB

Achieved shot-noise limit of -151.3 dBc/Hz

Simultaneous pulse amplification of 13.5 dB

Abstract

We propose a nonlinear fiber system for shot-noise limited, all-optical intensity-noise reduction and signal amplification. The mechanism is based on the accumulation of different nonlinear phase shifts between orthogonal polarization modes in a polarization-maintaining fiber amplifier in combination with an implemented sinusoidal transmission-function. The resulting correlation between the input intensity-fluctuations and the system transmission enables tunable intensity noise reduction of the input pulse train. In the experiment, the noise spectral density of a mode-locked oscillator is suppressed by up to ~20 dB to the theoretical shot-noise limit of the measurement at -151.3 dBc/Hz with simultaneous pulse amplification of 13.5dB.