Prediction of Macrobending and Splice Losses for Photonic Crystal Fibers based on the Effective Index Method

Abstract: - An index-guiding photonic crystal fiber (PCF) with an array of air holes surrounding the silica core region has special characteristics compared to conventional single-mode fibers (SMFs). Using the effective index method and the Gaussian beam propagation theory, the macro-bending and splice losses for PCFs are investigated. The wavelength dependence of the cladding index of the PCF has been taken properly into account. We obtain the effective spot size for different configurations of PCFs, which is used for computing the splice losses. The Gaussian approximation for the fundamental modal field leads to simple closed-form expressions for the splice losses produced by transverse, longitudinal and angular offsets. Calculations of macro-bending losses are based on antenna theory for bend standard fibers. Key-Words: - Photonic crystal fibers, modal properties, bending loss, splice losses, effective index method. 1 Introduction Photonic crystal fiber (PCF) is a unique type of optical fiber [1]-[3] incorporating an array of air holes that run along its length, reminiscent of a crystal lattice, which gives to this type of fiber, its name. There are two main types of PCF: air-guiding which guides light via a photonic band-gap effect and index-guiding which guides via a modified total internal reflection mechanism. In air-guided PCF, the core is hollow, and light is guided by the photonic band gap (PBG) effect, a mechanism that does not require a higher refractive index in the core in order to confine and guide light. The PBG guidance effect relies on coherent backscattering of light into the core.