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Three dimensional silicon-air photonic crystals with controlled defects using interference lithography

Interference lithography is an attractive technique for the creation of three dimensional photonic crystals. Structures with potential for photonic applications are fabricated in a photoresist through concurrent exposure with four coherent beams of laser radiation. The polymer-air templates are used to create higher refractive index contrast photonic crystals by infilling using atomic layer deposition followed by chemical vapor deposition. These photonic crystals exhibit excellent optical properties with strong reflectance peaks at the calculated band gap frequencies. Two-photon polymerization is used to demonstrate the ability to create designed defect structures such as waveguides in silicon-air photonic crystals.