Low-loss micro-machining of anti-resonant hollow-core fiber with focused ion beam for optofluidic application
Abubakar I. Adamu, Yazhou Wang, Rodrigo Amezcua Correa, Ole Bang, Christos Markos
Abstract
Hollow-core fiber (HCF) is a promising candidate for optofluidic applications because it can act as a gas-cell, permitting intense fluid-light interaction over extended lengths with low optical loss and inherent flexibility.Such a platform could pave the way for an all-fiberized, compact, robust and practical system for sensing applications.To facilitate this, we report a high-precision and repeatable micro-machining technique using focused ion beam (FIB) milling on a nodeless anti-resonant hollow-core fiber (ARHCF).Ga + ions are bombarded on a 43 µm thick outer cladding of ARHCF for 30 minutes, to create a 50 µm deep fluidic channel, that has a negligible influence on the guiding properties of the fiber.The milled channel, followed by the 2.8 µm gap between adjacent 500 nm thin capillary tubes, provides direct access for liquid/gas to diffuse into the hollow-core region.The novel design presented here will allow ARHCFs to be spliced with solid-core fibers while preserving the fluidic channel.Corroborating results from simulation of such a structure are presented to demonstrate that no additional loss is induced by the milled hole.