Thermally tunable and efficient second-harmonic generation on thin-film lithium niobate with integrated micro-heater

Abstract

In this Letter, we report thermo-optic tunable and efficient second-harmonic generation (SHG) based on an X-cut periodically poled lithium niobate (PPLN) waveguide. By applying an on-chip heater with thermo-isolation trenches and combining a type-0 quasi-phase matching mechanism, we experimentally achieve a high on-chip SHG conversion efficiency of 2500–3000% W−1 cm−2 and a large tuning power efficiency of 94 pm/mW inside a single 5-mm-long straight PPLN waveguide. Our design is for energy-efficient, high-performance nonlinear applications, such as wavelength conversion, highly tunable coherent light sources, and photon-pair generation.

Wavelength-accurate and wafer-scale process for nonlinear frequency mixers in thin-film lithium niobate

“…Wafer-scale fabrication of large arrays of QPM devices for SHG of λ 0 = 737 nm shows robustness to variations in etch depth and systematic errors in input parameters used in QPM grating design due to our calibration process. Where thermal tuning is possible, we demonstrate up to 96% operating at the 737 nm using an off-chip heater; future integration with efficient on-chip heaters 36 will allow individual devices to be tuned without affecting the remaining circuit. For applications where thermal tuning is not possible, such as interfacing with single-photon emitters at cryogenic temperatures 37 , we also demonstrate cladding trimming to blue-shift operating wavelengths by > 100 nm.…”