Wagner Gerd, Behrendt Andreas, Wulfmeyer Volker, Späth Florian, Schiller Max
Institute of Physics and Meteorology (IPM), University of Hohenheim (UHOH), Stuttgart 70599, Germany.
Appl Opt. 2013 Apr 10;52(11):2454-69. doi: 10.1364/AO.52.002454.
The Ti:sapphire (TISA) laser transmitter of the mobile, three-dimensional-scanning water-vapor differential absorption lidar (DIAL) of the University of Hohenheim is described in detail. The dynamically-stable, unidirectional ring resonator contains a single Brewster-cut TISA crystal, which is pumped from both sides with 250 Hz using a diode-pumped frequency-doubled Nd:YAG laser. The resonator is injection seeded and actively frequency-stabilized using a phase-sensitive technique. The TISA laser is operating near 820 nm, which is optimum for ground-based water-vapor DIAL measurements. An average output power of up to 6.75 W with a beam quality factor of M2<2 is reached. The pointing stability is <13 μrad (rms), the depolarization <1%. The overall optical-optical conversion efficiency is up to 19%. The pulse length is 40 ns with a pulse linewidth of <157 MHz. The short- and long-term frequency stabilities are 10 MHz (rms). A spectral purity of 99.9% was determined by pointing to a stratus cloud in low-elevation scanning mode with a cloud bottom height of ≈2.4 km.
详细描述了霍恩海姆大学移动三维扫描水汽差分吸收激光雷达（DIAL）的钛宝石（TISA）激光发射器。动态稳定的单向环形谐振器包含一块 Brewster 切割的单 TISA 晶体，使用二极管泵浦倍频 Nd:YAG 激光从两侧以 250 Hz 的频率进行泵浦。该谐振器采用注入种子技术，并通过相敏技术实现主动频率稳定。TISA 激光器在 820 nm 附近工作，这对于地基水汽 DIAL 测量是最佳的。实现了高达 6.75 W 的平均输出功率，光束质量因子 M2<2。指向稳定性<13 μrad（均方根），去偏振<1%。整体光光转换效率高达 19%。脉冲长度为 40 ns，脉冲线宽<157 MHz。短期和长期频率稳定性均为 10 MHz（均方根）。通过在低仰角扫描模式下指向云底高度约为 2.4 km 的层云，确定光谱纯度为 99.9%。
