Picometer resolution profilometer for hollow-core fiber surface roughness characterization

We build a picometer-sensitivity optical surface-profiler based on polarization-interferometry. The profilometer is design to measure surface roughness profiles of HCPCF. Two HCPCF categories with different fabrication processes were characterized. We observe that for HCPCFs fabricated the new process exhibit a reduction of rms core-surface roughness rms by a factor of close to 3 relative to the surface capillary wave thermodynamic limit, and thus explaining the record loss achieved in the VIS-UV range achieved with these fibers