Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers

TL;DR

This paper investigates polarization noise in hollow-core photonic crystal fibers caused by guided acoustic wave Brillouin scattering, revealing increased noise due to acoustic vibrations affecting the fiber's structure.

Contribution

It provides the first detailed analysis of polarization noise in hollow-core PCFs and explains it through acoustic vibrational mode simulations affecting the fiber's geometry.

Findings

Increased polarization noise in hollow-core PCFs compared to standard fibers

Acoustic vibrations modulate the fiber's geometry, causing polarization noise

Simulation results support the GAWBS-based explanation

Abstract

By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the fiber core as in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the effective refractive index by modulating the geometry of the photonic crystal structure. This induces polarization noise in the light guided by the photonic crystal structure.