LAUSR

Abstract In this work, a modified photonic crystal fibre (PCF) that we refer to as Sunny PCF with enhanced evanescent field exposure structure is proposed. The Sunny PCF with triangular interstitial air holes surrounding the core region increases the interaction of the guided mode with the air. Full-vectorial finite element method with perfectly matched layer boundary condition is used to design and simulate the sensitivity and confinement loss characteristics of the proposed Sunny PCF. By adding sunny structure to a conventional PCF with air-filling ratio of 0.9, the highest achievable sensitivity with negligible confinement loss can be boosted up to 21.23% from 15.83% at the operating wavelength of 1550 nm. Sunny PCF can achieve the same sensitivity as suspended-core holey fibre with lower confinement loss. A preliminary Sunny PCF has been fabricated to prove the feasibility of the proposed structure.