Lbo And Frequency To Generate The Numerical Simulation And Experimental Study Of The 589nm Laser Source

589 nm laser ,as a new type laser source, has great application on optical spectrography, laser allocation & guidance, astronomical observation and so on. Especially, sodium guide star has more notable goodness and profound significance than Rayleigh beacon used as man-made guide star.Unfortunately, stimulated radiant intensity at 1178 nm equal to 1064 nm and 1319 nm of Nd:YAG has not found yet, as well as corresponding laser medium. Therefore laser sum-frequency generation (SFG) is used, instead of second harmonic generation (SHG), to sum 1064 nm and 1319 nm basic frequency laser in LBO crystal to get expected 589 nm sodium yellow laser.Based on nonlinear optics, steady-state coupled wave equation was analyzed. As a result, phase-matching condition: Δk = 0 must be satisfied for higher light conversion efficiency. According to refractive index equation of double-axis crystal and dispersion relation of LBO crystal, phse-matching angle (θ-φ) graph of I type was numerically simulated by computer. Meanwhile, the condition of maximal d_eff and effective sum-frequency coefficient were figured out on this analytic solution, which provided theoretical guide to angle adjustment of the crystal. Besides, the crystal temperature influenced on experiment result was analyzed, and temperature matching condition of LBO was given out.Optimum length of LBO crystal correlated to total incidence power density I_in was discussed on both small-signal and high conversion efficiency instance. The function of energy distribution in crystal was counted, and connected plot of optimal crystal length versus total input power density was drawn by MATLAB software. According to total input power density of experiment, optimal crystal length could be easily got from the figure.Experimental scheme with sum-frequency was designed simply and efficiently. Nd:YAG laser pumped by diode respectively output 1064 nm and 1319 nm quasi-continuous laser through coated lens and tiltable etalon. The two basic beams were focused on LBO crystal with I type phase-matching condition and optimum length. When the rate of 1064 nm and 1319 nm photon was 1:1, 589 nm quasi-continuous yellow laser with power 500 mW and light-light transform efficiency 18%, was gained by adjusting two pulses synchronism. Otherwise, thermal lens and spatial hole burning offect were compensated optically to make beam quality M²≈2. Finally, considering later experimental sheme with mode-locked laser, we analyzed the reason of micropulse disarrangement, then designed a repeat frequency-locked system, of which locked deviation less than 0.01 Hz.