POWER CONVERSION EFFICIENCY IN 2ND HARMONIC-GENERATION WITH NONUNIFORM BEAMS

The efficiency of nonlinear optical conversion of fundamental to second harmonic power is analyzed for beams with arbitrary super-Gaussian shapes in time and/or space. A convenient change of variables is used to simplify the computational aspects of the problem and the number of free parameters. This transformation is used to generate nondimensional efficiency curves for both single- and two-crystal cascaded doubling schemes (e.g., quadrature schemes). Data are generated which enable the determination of optimal magnification/demagnification of the beam for high conversion efficiency. The results are a useful guide to the design of practical doubling arrangements, and reveal in a quantitative manner the differences between frequency doubling with spatially and temporally flat beams and doubling with the nonuniform beams more usually encountered in practice.