Design and Optimization of Photonic Crystal Triplexer for Optical Networks

In this paper, we have proposed an all-optical wavelength triplexer using photonic crystal resonant cavities. The photonic crystal rods is composed of three layers, InP-InGaAsP-InP, the substrate consists of InP with a refractive index of nInP=3.169 and the guiding layer is InGaAsP, with an index of nInGaAsP=3.364. The guiding layer is 0.510μm thick, and it has an InP top cladding of 1.500μm. The photonic crystal is created with a hexagonal lattice with r/a=0.18 which r is a radius of rods and a is lattice constant. In this structure, three cavities are used, which can separate three communication wavelengths, 1.31, 1.49 and 1.55μm. The average output efficiency of the proposed triplexer by using finite-difference time-domain (FDTD) method is above 97%. The footprint of the proposed structure is about 144μm, thus this structure is suitable for integration. Also, the crosstalk, which is critical factor in triplexer devices, is between −26.81dB ~ −13.80dB.