In hollow-core fibers, the scattering loss arises from the core roughness and represents the limiting factor for loss reduction regardless of the cladding confinement power. Here, we report on the reduction of the core surface roughness of hollow-core fibers by modifying their. Numkam Fokoua, Eric, Abokhamis Mousavi, Seyed, Jasion, Gregory T. Advances in Optics and Photonics, 15 (1). Over the past few years, progress in. F. The sustained pace of progress has sparked renewed interest in the technology, and created the expectation that they wi l one day become the most transparent optical waveguides across all spectral regions.