Single-photon infrared waveguide-based upconversion imaging

We report a nonlinear optical upconversion 3D imaging system for infrared radiation enabled by zinc indiffused MgO:PPLN waveguides. While raster-scanning a scene with an 1800 nm pulsed-laser source, we record time-of-flight information, thus probing the 3D structure of various objects in the scene of interest. Through upconversion, the 3D information is transferred from 1800 nm to 795 nm, a wavelength accessible to single-photon avalanche diode (SPAD).