Analytical evaluation of splice and bending losses of photonic crystal fibers based on empirical relations

Photonic crystal fibers (PCFs) have been under intensive study for the past several years as they offer a number of unique and useful properties not achievable in conventional silica glass fibers. Important issues regarding the practical development of these PCFs are their splice and bending loss properties. In this work, we present an analytical evaluation of the splice losses as well as bending losses for PCFs using simple empirical relations in order to determine the Petermann-I and Petermann-II spot sizes as a function of the fundamental geometrical parameters - the air-hole diameter and the hole-pitch of the PCF. We consider the splice loss due to lateral, longitudinal as well as angular offsets, when a PCF is spliced to an identical PCF or to a step index single mode fiber (SMF). To deduce macro-bending loss in PCFs, we apply the standard radiation model for bend conventional fibers, making a full transformation of conventional SIF parameters to PCF effective parameters. The spectral response of bending loss is also investigated. The results can be utilized in the design and development of telecommunication and sensor systems based on PCFs.