Abstract

Microstructured optical fibres (MOFs) enable efficient interaction between the guided optical field and gas / liquid species filling the holes. Long interaction lengths may be achieved in both photonic band-gap fibres (PBGFs) and suspended-core holey fibres (SC-HFs) [1], a property that can be exploited for high sensitivity optical sensing and spectroscopy applications. Most practical implementations to date, however, have been obtained by feeding the gas / liquid from the fibre ends. This approach has proven impractical due to slow diffusion through the holes [2], and the difficulty in simultaneously ensuring a stable optical input as well as access to the fluid, in a compact fashion. Here we report, for the first time to our knowledge, the implementation of a femtosecond laser micro-machining technique to produce additional ports of access to the fibre airholes. Radial micro-channels were fabricated, from the fibre surface to the hollow core of a PBGF (Fig. 1), and to any of the three holes in a SC-HF (Fig. 2), respectively. Such channels would allow faster in- or out-diffusion, with the advantage that the fibre ends may be spliced to conventional fibres -thus providing stable input or output coupling.

© 2007 IEEE