Nonlinear polarization imaging by parametric upconversion

Parametric upconversion, which can convert infrared (IR) light into the visible (VIS) band, has been regarded as a successful innovative strategy for IR detection. However, the traditional upconversion technique can get only intensity information of IR light, while completely dropping its polarization information. In this paper, we present a nonlinear polarization imaging technique based on parametric upconversion that can decipher near-IR (NIR) light polarization from that of upconverted VIS waves. Assisted by the parametric upconversion process in a nanometers thin lithium niobate film, the polarization states of NIR fundamental frequency (FF) light are encoded into the generated VIS wave. Based on the nonlinear Stokes-Mueller formalism developed here, FF polarization is successfully retrieved from upconverted VIS light. High-precision polarization imaging over various targets is demonstrated using our technique, which provides a fresh perspective on manufacturing novel polarimeters for various NIR polarization imaging and metrological applications. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement