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将多周期极化铌酸锂(PPLN)晶体置于激光二极管(LD)端面抽运的声光调QNd∶YVO4激光器谐振腔内,实现了准相位匹配内腔光学参量直接产生(QPM-IOPG)。PPLN晶体长20 mm,利用外加电场极化法制作,极化沿晶体的z向进行。设定声光Q开关重复频率为19 kHz,通过温度调谐和周期调谐,获得了信号光在1384~1541 nm范围内的连续输出,脉冲宽度约为80 ns。在PPLN晶体温度为140℃,极化周期为29μm时,内腔光参量产生的阈值仅为0.93 W,在3 W激光二极管抽运功率下,获得了140 mW的信号光输出;在极化周期为26.5μm时,内腔光参量产生的阈值增大到1.36 W,在3 W激光二极管抽运功率下,获得了105 mW的信号光输出。分析了不同极化周期下阈值和转换效率存在差异的原因,对内腔光学参量产生的阈值进行了理论分析和计算。
The multiphase polarized lithium niobate (PPLN) crystal is placed in the Q / Q QD Nd: YAG laser cavity pumped by the laser diode (LD) end face to achieve quasi-phase-matched cavity optical parametric direct generation (QPM-IOPG) . PPLN crystal length of 20 mm, the use of applied electric field polarization method, polarization along the crystal z direction. Setting the repetition frequency of the acousto-optic Q switch to 19 kHz, the continuous output of the signal light in the range of 1384 ~ 1541 nm was obtained through temperature tuning and period tuning, and the pulse width was about 80 ns. When the temperature of PPLN crystal is 140 ℃ and the polarization period is 29μm, the threshold value of the cavity optical parameter is only 0.93W, and the signal light output of 140mW is obtained under the laser power of 3W laser diode. During the polarization period At 26.5 μm, the threshold value of the lumen optical parameter is increased to 1.36 W, and a signal light output of 105 mW is obtained at the 3 W laser diode pumping power. The reason of the difference between the threshold and the conversion efficiency under different polarization cycles is analyzed. The threshold value of the optical parameters of the cavity is analyzed and calculated theoretically.