# Phase evolution of the direct detection noise figure of a nondegenerate fiber phase sensitive amplifier

## TL;DR

This paper experimentally studies how the noise figure of a fiber-based phase sensitive amplifier varies with phase, demonstrating agreement with theoretical predictions across the full gain range without pump dithering.

## Contribution

It provides the first detailed experimental analysis of noise figure evolution in a nondegenerate fiber phase sensitive amplifier across all phase conditions.

## Key findings

- Noise figure varies with phase as predicted by theory.
- High Brillouin threshold fiber enables full phase range investigation.
- Experimental results match theoretical models.

## Abstract

We experimentally investigate the evolution of the direct detection noise figure of a non degenerate phase sensitive amplifier based on nonlinear fiber, as a function of the relative phase between the signal, idler, and pump, all other parameters remaining fixed. The use of a fiber with a high stimulated Brillouin scattering threshold permits to investigate the full range of phase sensitive gain and noise figure without pump dithering. Good agreement is found with theory, both for signal only and combined signal and idler direct detections.