Methane Detection Using Single-Photon Upconversion in a PPLN Waveguide

Deployable solutions for the detection of greenhouse gases are critical for environmental monitoring in industrial settings. Single-photon light detection and ranging (LIDAR) techniques offer a route to high sensitivity. Many greenhouse gas molecules, such as methane, have overtone absorption features in the short-wave infrared, however, superconducting nanowire detectors are unsuitable for many field-based applications and InGaAs single-photon avalanche diode (SPAD) detectors drop in efficiency above ~1500 nm. Upconversion, through sum-frequency generation, offers a practical route to high photon detection efficiencies (PDE) across a broad range of short infrared (SWIR) wavelengths. The target wavelength is converted to a shorter wavelength by combining it with a pump laser in a nonlinear crystal for detection with high-efficiency silicon single-photon detectors.