Study of a Three-Dimensional Photonic Band-Gap Material in the Microwave Region

摘要

A microwave photonic crystal has been constructed and characterizedexperimentally and computationally. The material has prominent electromagnetic features characteristic of a three-dimensional photonic band structure material. Measurements of transmission and reflection coefficients show that the material has a first band-gap (i.e., a frequency gap where extended modes are forbidden) between 10.9-13.1 GHz. The damping of transmitted amplitude is typically -40 dB in this band-gap, and close to 0 dB (with dips due to interference effects reaching down to -8 db) within the bands (i.e. at frequencies where extended modes are allowed). Calculated transmission and reflection spectra agree qualitatively with measurements. The electric flux density and the time average Poynting vector (flow of electromagnetic power), have been calculated on a plane cut, parallel to the direction of incidence, through a model of the photonic crystal. Close to the first band-gap, the electric flux density amplitude has properties characteristic of standing wave modes in photonic band-gap crystals. It particular, the high-epsilon (sub tau) regions contain amplitude nodes right above the gap, and amplitude maxima right below the gap.