Tunable Mid‐Infrared Detail‐Enhanced Imaging With Micron‐Level Spatial Resolution and Photon‐Number Resolving Sensitivity

Abstract

The underdevelopment of mid‐infrared (MIR) components and detectors greatly limits the spatial resolution and sensitivity of MIR imaging. To overcome these limitations, MIR detail‐enhanced imaging is enhanced via non‐degenerate optical parametric amplification (OPA) pumped by a femtosecond vortex pulse. This design renders MIR illumination into a visible image by nonlinear wavelength‐conversion, together with a high OPA gain, large spatial bandwidth, and remarkable sensitivity. These experiments show that the design can realize MIR imaging with a spatial resolution of up to 114 line pairs per millimeter and a 2D spatial bandwidth product of up to 62 900, over a spectral region tunable from 2.0 to 3.0 µm. Equally important, this setup simultaneously achieves excellent imaging sensitivity of 25 photons at room temperature. It is thought that this work provides a powerful way to realize effective real‐time MIR imaging with an excellent spatial resolution even in very weak illumination environments, which can benefit many applications from semiconductor material characterization and biomedical imaging to security.