Experimental study and modelling of high-transmission defect modes in photonic crystals with graphite structure

The authors present an experimental demonstration and a modelling of high-t ransmission defect modes in graphite type photonic crystals. Such two-dimen sional crystals are of interest for applications in integrated optics due t o the existence of a complete forbidden band of relatively low order. Exper iments are currently performed at microwave frequencies using hexagonal lat tices of alumina rods to provide an easier and more accurate analysis of po int defect modes. The complete photonic bandgap extends from similar to 57 to 61 GHz. By introducing a row of vacancies in the crystal, we show that a sharp resonance can be created in the gap with a transmission level compar able to that obtained in the neighbouring transmission bands, Besides, a sh arp resonance with a transmission of -6 dB (similar to 25%) is obtained in the lowest forbidden band when six defects are arranged to form a small hex agonal cavity. The transmission spectra are well reproduced by numerical si mulations with a. finite difference time domain model which also gives the field pattern of the defect modes.