Research On 1.57μm Optical Parametric Oscillator Laser

First, this paper introduced OPO basic theory of second order nonlinear polarization. Phase matching technology of OPO was discussed and phase matching conditions of simple and practical application of biaxial crystal was obtained. The operation characteristics of OPO were analyzed. The gain expression of OPO was solved.Paper analyzed the influence of different transmittance Cr4+:YAG to inner-cavity power density according to Cr4+: YAG passive Q rate equation. Meanwhile, we established the resonant passive pulse tuning Q switch process. Paper analyzed the influence of different output mirror reflectivity to pulse characteristics and different output mirror reflectivity to pulse energy, summarized the Cr4+: YAG passively Q-switching laser parameter optimization design.Some KTP crystal transformation parameters of nonlinear coefficient, damage threshold, off the angle, pervious to light band, etc were analyzed. Paper used that 5w-LD end pumped Nd: YAG laser crystal. Cr4+: YAG as passively Q-switching crystal, obtained 10 ns fundamental frequency light oscillation at 1064 nm. And then we obtained 2.5ns of pulse width、5.6uJ of pulse energy 1.57 um laser output when we inserted critical phase matching KTP crystal into cavity.