Abstract

The photonic band structure of a 2D photonic band-gap crystal is investigated by using the coherent microwave transient spectroscopy technique.¹ A mode-locked, pulse-compressed, frequency-doubled Nd-YLF laser is used to switch planar antennas photoconductively. The freely propagating pulsed radiation generated by the coplanar strip horn antennas has a usable bandwidth extending from 5 to nearly 100 GHz. The crystal is made by drilling a parallel set of holes on a triangular lattice in a dielectric whose refractive index is 3.6. The theoretically determined optimal hole diameter is 0.96 times the lattice spacing. The photonic band structure for both the TE and TM modes and the attenuation length within the gap are mapped out directly by using the phase information obtained experimentally. These results are compared with theoretical predictions calculated by using the plane-wave expansion method.

© 1992 Optical Society of America