High beam quality and high energy Ho:YLF laser

Abstract

The capability of monitoring the greenhouse distribution and variation is of the essence for mankind sustainable development. Differential absorption lidar (DIAL) based on high energy 2 μm pulse lasers are favorable for the atmospheric CO₂ concentration remote sensing. Here we present a high energy Q-switched Ho:YLF laser with a ring cavity resonantly pumped by two self-made 1940 nm Tm:YAP solid-state lasers through polarization beam combining. In the operation of continuous-wave (CW), the maximum output power was 7.39 W at 2065.15 nm as the incident pump power was 33 W, corresponding to a slope efficiency and an optical-to-optical conversion efficiency were 40.75 % and 22.39 %. At 300 Hz, a maximum pulse energy of 21.23 mJ was obtained with the pulse width of 90 ns under 30.8 W pump power. The energy instability during 30 minutes was 1.01 % at the maximum pulse output energy. The beam quality factor M2 were 1.009 in x direction and 1.020 in y direction, respectively. The high energy high stability Ho:YLF laser also makes excellent potential sources for the following amplifiers as well as other applications such as surgery. With the continuing double pulse injection locking, a single frequency high energy pulse laser will be achieved for the CO₂ sensing DIAL.