Frequency upconversion detection for infrared imaging degenerate four-wave mixing spectroscopy

Summary form only given. Degenerate four-wave mixing spectroscopy (DFWM) has been used for the visualization of spatial distributions of species in a chemical environment like combustion. Compared with other imaging techniques one of the attractive features of DFWM is the fact it can be extended into the infrared spectral region where all molecules have their active transitions. With respect to imaging devices, on the other hand, an image-intensifier type device, which is useful for image amplification and for a fast time-gated operation, is not available in the IR. When we take into account that DFWM generates a laser-like coherent signal, the frequency upconversion of a DFWM signal in a nonlinear crystal followed by an image-intensified CCD camera will become very attractive as a detection scheme. This scheme has the following advantages: (1) the upconversion process acts as a spatial and wavelength filter; (2) fast-gated operation down to subpicosecond levels is possible using a short pulse pump laser; (3) image amplification is possible using the parametric amplification process. In this presentation, the upconversion detection of infrared degenerate four-wave mixing image for infrared imaging spectroscopy was proposed and demonstrated.