Mid-Infrared Slow Light Engineering and Tuning in 1-D Grating Waveguide

The design, fabrication, and characterization of 1-D grating waveguide as slow light structure working in mid-infrared (MIR) region are demonstrated for the first time. The effects of various structural parameters on slow light properties are investigated through theoretical analysis, simulation and experimental verification, providing guidance on slow light engineering in 1-D grating waveguide. By adjusting structural parameters, average group indices of 9.4-15.5 with bandwidths of 23-66 nm and normalized delay-bandwidth products of 0.093-0.164 are obtained. Thermo-optic tuning is also demonstrated with π phase shift and group index tuning from 23 to 33 at the wavelength of 3.9024 μm by applying 1.4 mA current. The proposed tunable 1-D grating slow light waveguide provides a promising platform for various MIR applications such as on-chip absorption-based biochemical sensors, tunable optical buffers, and thermo-optic modulators.