A Theoretical Study on Mid-Infrared Difference Frequency Generation Based on Periodically Poled Thin-Film LiNbO3

A mid-infrared difference frequency generator (DFG) based on a periodically poled thin-film lithium niobate rib waveguide sapphire substrate is theoretically studied. mode analysis carried out at the region, and focuses effects of geometry effective refractive indices few lower-order modes. complete theory suitable for modeling DFG structure described. Its validity confirmed by comparing theoretical results with previously reported experimental data. Explicit expressions are presented nonlinear conversion efficiency, thermal tunability quasi-phase matching (QPM) bandwidth. The hybridization field area overlap factor, which either inversely or linearly proportional to studied in detail. In this article, an optimized improved that exhibits excellent performance, including higher efficiency 230–273% W−1cm−2 temperature range 20–120 °C; larger 2.2 nm/°C; QPM bandwidth ~130 nm; idler wave output power, as much −2 dBm when Pp = 20 Ps 11.5 dBm, suggested.