Two-dimensional silicon-based photonic crystal slab with partial air-bridge

We describe a fabrication process of the near-infrared two-dimensional photonic crystal (PC) slab, which is sustained by part of the silica layer underneath the slab and forms a partly air-bridged type. The process involves focused ion beam (FIB) direct write following the selective wet etching of silicon on isolator (SOI) structures. By control the time of dissolving of silica layer in SOI, we successfully fabricated the sample and measured its transmittance spectrum. It is found that the observed spectrum is consistent with the theoretical band structure with FDTD method. For there is partly silica layer remained to support the air-bridge slab, the PC can be fabricated with a large area. If we change the support material under the slab, we might be able to fabricate PC laser with this kind of structure.