Shanghai Optics and Machinery Institute has made new progress in the research of high repetition frequency and high energy medium wave infrared lasers

Recently, the research team of Aerospace Laser Technology and System Department of Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, based on 2.1 μ M Ho: YAG main oscillator amplifier pumped ZGP crystal, achieving high energy 3-5 at kHz repetition frequency μ The output of M medium wave infrared laser and further research on beam quality improvement technology for high-energy medium wave infrared laser. The relevant research results have been published in the Journal of Lightwave Technology and Laser Physics Letters, respectively, titled "High Repetition Rate 52-mJ Mid Infrared Laser Source Based on ZnGeP2 MOPA System" and "High repetition frequency, high energy mid wave infrared ZnGeP2 MOPA system".

High repetition rate, large pulse energy tunable 3-5 μ The mid infrared laser has important significance in many fields such as atmospheric monitoring. Among the methods that can achieve medium wave infrared laser output, nonlinear frequency conversion technology has advantages such as all solid-state, wide wavelength tuning range, and less heat generation. Due to the damage threshold of solid materials, the current pulse energy of medium wave infrared lasers at the kilohertz repetition rate level is only~10mJ, which is difficult to meet the needs of application fields.

In this study, researchers compensated for the crystal thermal lens and thermally induced birefringence depolarization effect through optical and structural design, and ultimately achieved high polarization 2.1 with a repetition frequency of 2kHz and an average power of~200W using the Ho: YAG MOPA system μ M laser output. By using its pumped ZGP optical parametric oscillator and amplifier, a 3-5 pulse repetition rate of 2kHz, average power of 103.9W, pulse energy of~52mJ, and pulse width of 18.3ns were achieved μ M produces mid infrared laser output, but there is a problem of poor beam quality (M2=10) in mid wave infrared laser. By studying techniques such as pump allocation ratio, single wavelength injection, and amplifier seed and pump divergence angle matching, the beam quality M2<4 was achieved at an average power of 53.3 W and a pulse energy of 26.7 mJ for medium wave infrared lasers. This research work has achieved high brightness, high repetition rate, and high-energy medium wave infrared laser output, enhancing the application prospects of this type of laser.

This work is supported by the National Natural Science Foundation of China.

Figure 1 Structure diagram of high repetition rate and high energy medium wave infrared laser device

Figure 2 ZGP OPA Output Power and Pulse Width

Figure 3 Medium wave infrared laser spectrum
Source: Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences