Investigations On CW LD Side-Pumped High-Repetition-Rate 266nm UV Laser

Diode pumped all-solid-state ultraviolet laser (UV DPL) concentrate the merits of DPL that are compactness, stable performance and high efficiency, and the merits of UV laser that are short wavelength, small light spot, better photon capability and high resolution. So it is widely used in materials processing, optical data storage, chemedical, environment testing etc. In this paper, we obtain to transform 1064nm infrared laser to 266nm ultraviolet laser through nonlinear frequency conversion technology. Based on this approach, in the experiment we using CW LD side-pumped passively Q-switched Nd3+:YAG which got high-repetition-rate of 1064nm frequency laser, the extracavity second harmonic generation and fourth harmonic generation to obtain high-repetition-rate of 266nm ultraviolet laser. The major theoretical analysis and experimental examination details were summarized as follows:(1) On the basis of the physical and optical properties of Nd3+:YAG, through the sinmplified four-level laser rate equations, we got the CW LD passive Q-switched rate equation, and the expression of the parameters such as single pulse energy, paek power and pulse width and so on. Under the basic principle of laser amplification, the energy output and magnification of the laser amplifier was calculated.(2) We analyzed and summarized the characteristics of the concave-convex cavity and optimally designed the cavity structure parameters through the cavity analysis of g parameter and ABCD transfer matrix of Gaussion beam. We presented the theoretical basis for the selection of frequency doubling crystal, and determined the optimal frequency doubling crystal.(3) According to transient three wave coupling equations and phase-matching technologies, KTP and BBO matching parameters and harmonic conversion efficiency equations were simulated in the process of frequency-doubling.(4) The experimental research was carrying on which is based on the theory analysis, by the way of LD side-pumped, Under the circumstances that the injection current and repetition rate were 18A and 4kHz, ultraviolet laser was achieved and average output power of 30mW. The conversion efficiency of green-ultraviolet is 5.23%.