Hexagonal Resonator in Two Dimensional Photonic Crystal Structure

Propagation and filtering characteristics of two dimensional pillar-type photonic crystal wave guide with hexagonal resonator were experimentally demonstrated. Measurement was done by using a scale model in microwave frequency with lattice period P=26.5 mm, diameter of pillar phi=7.5 mm and its dielectric constant epsilon_r=36.0 around 4 GHz. First, single isolated wave guide was set up by using line-defect in array of pillars. After confirming wave guide operation in frequency range between 3.6 and 4.2 GHz, a hexagonal resonator which have side length of 4P along with center of resonator wave guide, was situated between a pair of input/output wave guides. The hexagonal resonator showed frequency dependent transmission characteristics to output ports at frequencies corresponding to lambda_g as propagating wave. Applying good separation characteristics with respect to input frequency, this resonator circuit is available for signal drop device for wavelength division multiplexing (WDM) system.