Room temperature photon-counting lidar at 3 μm

A midinfrared single-photon-counting lidar at 3 mu m is presented. The 3 mu m photons were upconverted to 790 nm in a periodically poled rubidium-doped KTiOPO4 crystal through intracavity mixing inside a 1064 nm Nd:YVO4 laser and detected using a conventional silicon single-photon avalanche detector (SPAD). The lidar system could distinguish 1 mm deep features on a diffusely reflecting target, limited by the SPAD and time-tagging electronics. This technique could easily be extended to longer wavelengths within the transparency of the nonlinear crystal. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License.