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.Comment: 8 pages, 5 figure
