Impedance of photonic crystals and photonic crystal waveguides

We develop and demonstrate the concept of impedance for a photonic crystal by generalizing the transverse wave impedance of conventional waveguides. The impedance involves a ratio of transverse fields and power flux. The calculated impedance for a two-dimensional photonic crystal is very well defined using the transfer matrix method. The predicted frequency-dependent reflectance from this impedance agrees very well with rigorous transfer matrix calculations for band modes and waveguiding modes in the band gap. This impedance concept will be very powerful in minimization of insertion loss into photonic crystal waveguides, designing waveguide splitters, and for modeling reflectance/transmittance from photonic crystals. (C) 2004 American Institute of Physics.