Waveguide-based photonic microstructures in semiconductors

The promising concepts of photonic microstructures are finally beginning to enter the realm of optical wavelengths: following a number of years of speculative theoretical work and experiments in the microwave regime, we present the first demonstration of strong photonic bandgap effects in semiconductors at optical wavelengths below 1 μm. We have observed both short and long wavelength band-edges in a 2-D waveguide structure and microcavity effects in a 1-D waveguide structure. Typically, the 2-D lattices consist of a hexagonal close packed (HCP) array of holes etched into the semiconductor (“honeycomb structure”) with a period of 190 nm, a hole diameter of 100-120 nm and an etch depth of 0.5-0.6 μm. The 3^d order 1-D microcavity structure has a period of 400-500 nm and incorporates a λ/4 phase shift. From the spectral response, we can assign a Q-value of approximately 2500 to this λ/4 microcavity. To our knowledge, this is the highest quality factor of all waveguide-based photonic microcavities either proposed or demonstrated to date