Visualization of infrared point images by a nonlinear optics method using a cylindrical pump wave

The paraxial approximation is used in the development of a theory for the visualization of monochromatic infrared point images using a cylindrical pump wave. The theory is based on the application of the classical Green's functions. One of the possible waves of efficient visualization is considered in detail. Expressions are obtained for the converted image field and, in particular, for the plane of the best image along two mutually perpendicular directions. These expressions describe qualitatively the astigmatism of the visualized image field. Illustrative numerical calculations are given for LiNbO₃, LiIO₃, and Ag₃AsS₃. Experimental investigations are reported of the visualization, with the aid of a cylindrical pump wave, in LiNbO₃ and LiIO₃ crystals under degenerate conditions, i.e., in the frequency doubling regime. In particular, a study is made of the nature and degree of astigmatism of the visible image field. The experimental results are in satisfactory agreement with the theoretical predictions.