Wide-field-of-view photonic bandgap filters micromachined from silicon
Wide-field-of-view narrow-band spectral filters have been fabricated and characterised at millimetre-wave frequencies. The devices use silicon/air two-dimensional photonic crystals with a defect layer that has twice the periodicity of the surrounding structure. Over a 120 field-of-view they show only a 0.4-GHz shift in their centre frequency (84 GHz), which is less than the full-width-half-maximum of the transmission peak (1.1 GHz). This performance is more than an order of magnitude better than the equivalent structures with the defect periodicity equal to that of the surrounding photonic crystal, making them a viable alternative for use in wide-field-of-view millimetre-wave imaging applications.
photonic bandgap filter silicon micromachining millimetre wave electromagnetic simulations