Deeply etched two-dimensional photonic crystals fabricated on GaAs/AlGaAs slab waveguides by using chemically assisted ion beam etching

High quality two-dimensional photonic crystals were fabricated by electron-beam lithography and a combination of reactive ion etching (RIE) and chemically assisted ion beam etching (CAIBE) in GaAs/AlGaAs slab waveguides. With optimized parameters, etch depths of more than 2 μm were achieved. This technique was used to fabricate three-dimensionally confined optical microcavities defined by a slab waveguide and a two-dimensional photonic crystal mirror structure. The optical quality of the deeply etched structures were tested by optical spectroscopy. The Q-factor of the cavity mode is dependent on the structural quality and depth of the holes in the photonic crystals. Due to the large etch depth and smooth surfaces, high quality planar microcavities could be realized with Q-factors of about 1000.