Photonic crystal fiber devices

Abstract

Photonic crystal fibers (PCFs) have been receiving increasing attention over the past few years. They are single material fibres that use an array of air holes in the cladding to confine light to a core, instead of the more usual refractive index step within the solid material of a conventional fibre. As PCFs become more well-understood mainstream structures, the need arises to develop techniques to process them post-fabrication to form all-fibre devices. We have chosen to study heat-treatment processes analogous to the tapering of conventional fibres, except that in PCFs there is a second degree of freedom to exploit. Not only can the fibre be stretched to locally reduce its cross-sectional area, the air holes can be changed in size by heating alone under the effect of surface tension.