Nondestructive measurement of the roughness of the inner surface of hollow core-photonic bandgap fibers

Xavier Buet (1, 2, 3) , Coralie Brun (2, 3) , Jérôme Gâteau (1) , Bruno Bresson (4) , Seyed Reza Sandoghchi (5) , Eric Numkam Fokoua (5) , Marco Petrovich (5) , Francesco Poletti (5) , David Richardson (5) , Damien Vandembroucq (3) , Gilles Tessier (1, 2)

1 UMR 8250 - Laboratoire de Neurophotonique
2 IL - Institut Langevin - Ondes et Images (UMR7587)
3 PMMH - Physique et mécanique des milieux hétérogenes (UMR 7636)
4 SIMM - Sciences et Ingénierie de la Matière Molle
5 Optoelectronics Research Centre

We present optical and atomic force microscopy measurements of the roughness of the core wall surface within a Hollow Core Photonic Bandgap Fiber (HC-PBGF) over the [3×10-2 μm-1 – 30 μm-1] spatial frequency range. A recently developed immersion optical profilometry technique with picometer-scale sensitivity was used to measure the roughness of air-glass surfaces inside the fiber at unprecedentedly low spatial frequencies, which are known to have the highest impact on HC-PBGF scattering loss and thus determine their loss limit. Optical access to the inner surface of the core was obtained by selective filling of the cladding holes with index matching liquid using techniques borrowed from micro-fluidics. Both measurement techniques reveal ultra-low roughness levels exhibiting a 1/f spectral power density dependency characteristic of frozen surface capillary waves over a broad spatial frequency range. However, a deviation from this behavior at low spatial frequencies was observed for the first time.

Domaines: Matière Molle [cond-mat.soft]

Xavier Buet, Coralie Brun, Jérôme Gâteau, Bruno Bresson, Seyed Reza Sandoghchi, et al.. Nondestructive measurement of the roughness of the inner surface of hollow core-photonic bandgap fibers. Optics Letters, 2016, 41 (21), pp.5086-5089. ⟨10.1364/OL.41.005086⟩. ⟨hal-01447953⟩