• High Power Laser Science and Engineering
  • Vol. 8, Issue 4, 04000e39 (2020)
Yunpeng Wang, Youlun Ju, Tongyu Dai*, Dong Yan, and Baoquan Yao
Author Affiliations
  • National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin150001, China
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    A single-frequency pulsed holmium-doped yttrium lithium fluoride (Ho:YLF) amplifier pumped by a Tm-doped fiber laser was demonstrated. The seed was an injection-seeded Q-switched Ho:YLF laser. The output energy from the single-frequency pulsed amplifier was 24.2 mJ, with a pulse width of 250 ns at a pulse repetition frequency (PRF) of 100 Hz. The energy stability during 30 min was improved to 1% after the single-frequency pulsed Ho:YLF laser was amplified. The line width of the single-frequency pulsed spectrum of the Ho:YLF amplifier was 2.81 MHz. The single-frequency pulsed Ho:YLF amplifier can be applied to differential absorption lidar (DIAL), since its output spectrum is around the P12 CO2 absorption line.

    1 Introduction

    Narrow-line-width pulsed solid-state lasers in the 2 μm eye-safe spectral region are usually used as the lidar emitter in coherent Doppler lidars for wind field measurement or in differential absorption lidars (DIALs) for monitoring the concentrations of gases such as CO2 and H2O[14]. A lidar configuration requires an emitter with high energy to increase the detection range, a long pulse width to improve the spectrum resolution and a narrow line width to enhance the spectral purity[5]. A critical technique for obtaining a narrow-line-width pulsed laser is the injection of a single-frequency continuous-wave (CW) laser into a Q-switched slave laser[6,7]. In addition, there are two ways to obtain a long pulse width: one is to increase the cavity length of the Q-switched slave laser; and the other is to ensure that the slave laser operates at a lower energy. Increasing the cavity length, however, leads to difficulties with the cavity design, a complex structure and a large laser volume. Compared with a longer resonator, it is an effective approach for realizing a pulsed laser with narrow line width, long pulse width and high energy, by making the Q-switched slave laser operate at a lower energy and then increasing the output energy through an amplifier system.