Tuning 2-D silicon photonic crystals

During the past several years there has been considerable interest in photonic crystals which are periodic dielectric materials with periodicity on the order of the wavelength of light. These crystals can manipulate light through Bragg diffraction and novel dispersion bands. Because of the underlying periodicity, and for suitable dielectric contrast, photonic crystals can possess a spectral region known as a photonic bandgap over which light can be inhibited from propagating. Many applications have been proposed for photonic crystals, including spontaneous emission control, waveguides and filters. However, the range of applications for photonic crystals would be significantly enhanced if the bandstructure of the crystals could be tuned. This might enable the realization of highly-integrated microchips for optical signal processing. Here I review our recent work on linear and nonlinear methods to tune the optical properties of photonic crystals. In particular I focus on tuning mechanisms related to the use of liquid crystals and optically injected electron-hole plasmas