Air-bridged photonic crystal slabs at visible and near-infrared wavelengths

Air-bridged photonic crystal slabs are demonstrated at visible and near-infrared wavelengths. We present experimental and theoretical studies of the transmission spectra of air-bridged photonic crystal slabs with free space illumination using collimated and focused beams. We show that the resonances of an air-bridged photonic crystal slab exhibit considerable differences in their sensitivity to the angle of illumination. We show that the variation in the quality factor of a resonance with the incident angle of illumination is determined by the symmetry of its field distribution. Last, we present experimental and theoretical results on the transmission spectra of air-bridged photonic crystal slabs with focused illumination, important due to the finite angular spread of real optical beams.