Application of Ultrafast Optoelectronics to the Characterization of Photonic Crystals

Abstract

The application of coherent microwave transient spectroscopy to the characterization of photonic band structure will be discussed. The dispersion relation for electromagnetic wave propagation in two-dimensional dielectric arrays is measured. We will also report the observation of surface waves in these photonic crystals. The analogy between electromagnetic-wave propagation in arrays of dielectrics and electron-wave propagation in crystals is now well known. For example, the scattering and interference of electromagnetic waves in uniform arrays of dielectrics gives rise to regions of the spectrum in which transmission is mniDited (i.e. band gaps) [1,2]. By extension, the dispersion of allowed modes in these "photonic crystals" is expected to resemble electronic band structure in real crystals. In this talk, we describe the application of ultrafast optoelectronics to the characterization of photonic crystals. The dispersion relation for electromagnetic wave propagation in arrays of dielectric cylinders is measured using the coherent microwave transient spectroscopy (COMITS) technique [3,4]. Using prism coupling and COMITS in reflection, the existence of surface modes in suitably-terminated cylinder arrays is demonstrated, and the dispersion of this mode is measured.