1 Department of Photonics Engineering, Technical University of Denmark2 Optical Sensor Technology, Department of Photonics Engineering, Technical University of Denmark3 Risø National Laboratory for Sustainable Energy, Technical University of Denmark
Two dimensional mid-infrared upconversion imaging provides unique spectral and spatial information showing good potential for mid- infrared spectroscopy and hyperspectral imaging. However, to extract spectral or spatial information from the upconverted images an elaborate model is needed, which includes non-collinear interaction. We derive here a general theory providing the far field of the upconverted light when two arbitrary fields interact inside a non linear crystal. Theoretical predictions are experimentally verified for incoherent radiation and subsequently applied to previously published data with good agreement.