Fabrication and Characterization of 2-Dimensional AIGaAs Photonic Crystals with High Aspect Ratio Hole Patterns by C1_2 RIBE

摘要

AlGaAs-based two-dimensional photonic crystal (PC) slab waveguide devices have been fabricated using electron beam (EB) lithography and a reactive ion beam etching (RIBE) technology. Air hole-based triangular lattices with lattice constants ranging from 0.32 to 0.45 have been fabricated on three kinds of structures, that is, semiconductor-clad (SC), air-bridge (AB) and oxide-clad (OC) structures. For the SC-type structure, periodic air-hole structures were fabricated in an MBE grown 0.5 μ-thick Al_(0.1)Ga_(0.9)As waveguide (core) layer and a 2.0 μm-thick Al_(0.35)Ga_(0.65) As cladding layer on a GaAs substrate. The etch depth of the air hole is 0.9μm. A series of samples were prepared with air-filling factors in the range of 0.3 to 0.5. The AB-type structure, giving strong optical confinement, was fabricated by selective wet chemical etching. After wet etching the air-filling factors measured for different samples ranged from 0.47 to 0.64. An OC-type structure, with a cladding layer with a much lower refractive index as compared to the core layer, was fabricated by selective wet thermal oxidation of the AI_(0.93)Ga_(0.07)As layer. Each PC structure was sandwiched with a pair of 3-μm-wide dry-etched stripe waveguides. In the transmission/reflection spectra with a wavelength ranging from 0.85 to 1.1 μm on three such kinds of devices, band-gaps with a large attenuation of more than 30 dB were observed.