Optimization of mid-infrared dispersive wave generation at 3 µm in LiNbO3 waveguides

Abstract

We propose an effective scheme to enhance mid-infrared dispersive wave (DW) emission, which includes dispersion engineering of the waveguide and the assistance of a CW trigger. Our suggested approach can help achieve better coherence and higher signal-to-noise ratio by adding a weak CW trigger with the femtosecond pulse pump in dispersion engineered lithium niobate (LiNbO3) waveguides. First, the integrated dispersion profile of LiNbO3 waveguides is designed based on dispersion engineering regarding the sidewall angle and slab thickness. Second, with the assistance of a weak CW trigger, the mid-infrared DW is enabled or further enhanced. The optimal CW-triggered wavelength and operating conditions are ascertained. Mid-infrared emission at around 3 µm with a sufficient power level is accessible after optimization, which is feasible for multi-species greenhouse gas detection through gas absorption spectroscopy.