Simulation Research For 266nm UV Frequency-doubled Light Field Based On Ray-tracing

The light field distribution is an important factor affecting laser properties. An evenly distributed light field is the prerequisite for good beam quality in output laser. In this paper,based on laser frequency-doubling theory and ray-tracing method, the study aims at researching light field distribution after frequency-doubling, therefore provides a theoretical basis for improvement of laser beam quality after frequency-doubling.Based on the physical process of laser frequency-doubling, and phase match theory of nonlinear crystal, the ray-tracing method was applied to build a mathematical model of intensity distribution of green laser beam. Then, the intensity distribution of green beam through nonlinear crystal was acquired. At last, the field distribution of frequency-doubled UV beam at certain distance was obtained. Combined with a frequency-doubling model of UV beam at 266 nm, the light conversion efficiencies were calculated with the aid of phase mismatch theory. Also MATLAB was used to simulate the influences on field distribution of frequency-doubled UV beam with varied laser power of green beam, and different length of BBO crystal.An experiment system was built to study the light field distribution of ultraviolet laser.The field distribution of green beam was measured by beam quality analyzer at different laser power and so did that of 266 nm frequency-doubled UV beam. It was found out that experiment results accorded well with simulation results.