Picometer-Resolution and High Dynamic-Range Profilometer for Hollow-Core Fiber Surface Roughness Characterization

While the cladding design of inhibited-coupling hollow-core photonic crystal fibers (IC-HCPCF) sets their transmission performance in the infrared wavelength range
$(\lambda > 1\mu \mathrm{m})$
, the limiting factor in their transmission loss at shorter wavelengths is set by surface scattering loss (SSL) [1]. As the SSL depends on the HCPCFs' core surface roughness (SR) arising from thermally-induced surface capillary waves (SCW) occurring during fiber drawing, the characterization of its core surfaces, achieved by either atomic force microscopy (AFM) [2] or optical profilometry [3], becomes of paramount importance.