水汽差分吸收激光雷达发射机935 nm高功率光参量振荡器

水汽分子的3强振动吸收带位于935 nm附近，差分吸收激光雷达在这个波段具有高探测灵敏度。不幸这一波段位于Ti:Sapphire激光器增益带宽的边缘和Cr:Alexandrite激光器增益带宽之外，染料激光器有较高的自发荧光成分而使其光谱纯度不高，光参量频率转换器可以用作该波段水汽差分吸收激光雷达的发射机。动态稳定的环形谐振腔中有一对走离补偿的、70.7切角的KTP非线性晶体。它由种子注入单纵模Nd:YAG激光器的二倍频532 nm光脉冲泵浦，脉冲重复频率10 Hz。通过935 nm分布反馈半导体激光器种子注入和ramp-hold-fire方法，主动锁定光参量振荡器谐振腔的腔长。发射机平均输出功率达到4.5 W，脉冲长度6 ns，光（532 nm）-光（935 nm）转换效率大于17%，光频的短程和长程频率稳定性30 MHz（RMS）。光束质量M2大约7.8，光谱纯度可以达到99.9%。它将是空间探测大气水汽廓线遥感器的候选光源之一。

High-power optical parametric oscillator at 935 nm for water-vapor differential absorption lidar transmitter

3 vibrational absorption band of water vapor lies in the 935 nm spectral region. Differential absorption lidar has much higher measurement sensitivity in this region. Unfortunately, this spectral region is already at the edge of the gain bandwidth of Ti:Sapphire lasers and outside gain bandwidth of Cr:Alexandrite laser. Spontaneous fluorescence radiation of tunable dye laser is higher, which makes their spectral purity declinable. So optical parametric frequency convertor can be used as the transmitter for water-vapor differential absorption lidar(DIAL). The dynamically-stable ring resonator contains dual 70.7 cut, walk-off-compensated KTP nonlinear crystals, which is pumped with an injection seeded, frequency-doubled 532 nm Nd:YAG laser with repetition frequency of 10 Hz pulse. The resonator length of OPO was actively locked by injecting the distributed feedback semiconductor lasers of 935 nm and using ramp-hold-fire technique. The average output power of the transmitter was 4.5 W, the pulse length was 6 ns, the conversion efficiency of light (532 nm) to light (935 nm) was more than 17%, and the short-range and long-range frequency stability of light frequency was 30 MHz(RMS). The beam quality M2 was about 7.8, and the spectral purity can reach 99.9%. It will be one of the candidate light sources for remote sensing of atmospheric water vapor profiles.