We propose the new concept of an optical triplexer for an application of Gigabit Ethernet Passive Optical Network (GEPON)
to Fiber-To-The-Home (FTTH) network. Based on a photonic crystal structure with local point defects, the optical
triplexer is optimally designed. The proposed device is analyzed by the plane wave expansion method and its
performance characteristics are evaluated by the finite-difference time-domain method. The optical triplexer proposed
here is designed to have a compact size of about 4 × 3 μm<sup>2</sup> and the extinction ratios of -32.33 dB for 1310 nm, -19.84 dB for 1490 nm and -29.93 dB for 1550 nm, respectively.