Air-Suspended Fast Transient Tunable Silicon Photonic Crystal Waveguide

We report an air-suspended ultracompact (30 μm× 40 μm) fast transient thermo-optic silicon (Si) 2D photonic crystal (PhC) waveguide (WG) operated at around telecommunication S-band. A line defect triangular lattice PhC WG was fabricated on a silicon-on-insulator substrate with a 220-nm-thick Si layer on 2- μm-thick buried oxide. The oxide layer was partially removed to air-suspend the 2D slab Si PhC to shift cutoff wavelength by localized heating through integrated NiCr microheaters. The cutoff wavelength of the PhC light modulator was 1465 nm at room temperature, but it was shifted 17 nm when 120 mA was applied. The transient time was estimated to 6.5 μs in rising time and falling time.