Coupling characteristics of 1×4 power splitter based on multicore photonic crystal fiber with square-lattice configuration

We propose a novel structure of 1×4 power splitter based on multi-core square-lattice photonic crystal fiber (PCF) that is composed of four neighboring outer cores and a central incident core. The coupled-mode theory for five identical propagation cores is demonstrated to understand the coupling characteristics for the proposed multi-core PCF splitter. The coupling behaviors along longitudinal propagation direction between the central and neighboring cores are accurately investigated by using the finite element method (FEM) and the beam propagation method (BPM). Through the numerical analysis, it is shown that the optical power launched into the central incident core is able to be equally divided into other neighboring four cores with about 25% of coupling ratio in a several-millimeter long PCF at the operating wavelength of 1.55 μm. The power coupling characteristics obtained through the BPM are in very good agreement with that calculated from coupled-mode theory.