Mid-infrared wavelength conversion using a composite Si3N4-HfO2 waveguide device

We report the design and numerical analysis of a composite HfO₂-coated-Si₃N₄ waveguide pumped with femtosecond laser pulses at 1550 nm for mid-infrared wavelength generation at 4.0 µm. The principle of wavelength conversion is based on the degenerate four-wave-mixing in designed HfO₂-coated-Si₃N₄ waveguide. The waveguide design and the dispersion engineering to get the desired phase matching conditions have been discussed. The advantages of composite Si₃N₄-HfO₂ waveguide over Si3N4 strip waveguide include high damage threshold, better electromagnetic interaction and thus strong light confinement, and relatively longer wavelength conversion in the mid-infrared region. Such on-chip composite Si₃N₄-HfO₂ waveguide generating mid-infrared light at 4.0 µm holds considerable potential for the applications in a wide range of the mid-infrared nonlinear optical devices.