基于亚纳秒微片激光器的能量放大器的研究

高脉冲能量和窄脉冲宽度的激光放大器可以应用在诸多领域，例如激光加工、激光医疗美容和激光雷达。种子源激光器与行波放大结构相结合的主振荡功率放大（MOPA）技术，既能保证输出的脉冲激光相关特性（如脉宽和重复频率等）与种子源特性一致，又能实现激光输出能量的放大。因此MOPA技术成为激光放大器工程应用中的主要技术。本课题针对医疗美容对亚纳秒级大能量激光放大器的需求，研制了一台基于亚纳秒微片固体激光器的激光放大器。首先，采用亚纳秒被动调Q微片固体激光器作为种子源。种子源激光器在重复频率为10 Hz，脉冲宽度为487.3 ps时输出能量为190 μJ的1064 nm种子光。然后，利用自制的两个氙灯泵浦Nd: YAG模块作为主放大器对亚纳秒激光脉冲能量进行放大，对放大过程自激振荡产生的能量实现了抑制，有效地提高了放大过程中的能量转换效率。最终，得到了波长1064 nm和532 nm可切换输出，在重复频率为10 Hz时，获得了脉冲宽度496.4 ps，脉冲能量561 mJ@1064 nm，330 mJ@532 nm，能量稳定性2%且光斑均匀的亚纳秒激光输出。

Research on energy amplifier based on sub-nanosecond microchip laser

Laser amplifiers with high pulse energy and narrow pulse width can be used in many fields, such as material processing, medical plastic surgery and lidar. The Master Oscillator Power Amplification (MOPA) technology, which combining the seed laser and the amplifying structure, not only enables features of the output pulse laser are consistent with that of the seed laser (pulse width and repetition frequency, etc.), but also ensures the amplification of the output laser energy. Thus, MOPA technology becomes the main technology in laser amplifier based on engineering applications. In this subject, a laser amplifier based on a sub-nanosecond microchip solid-state laser was developed in response to the demand for sub-nanosecond high-energy laser amplifiers in medical cosmetology. Firstly, a sub-nanosecond passive Q-switched microchip solid-state laser was used as the seed source. The seed source laser has a repetition frequency of 10 Hz, a pulse width of 487.3 ps, and a wavelength of 1064 nm to output seed light with an energy of 190 μJ. Then two self-made xenon lamp-pumped Nd:YAG modules were used as the main amplifier to amplify the sub-nanosecond laser pulse energy. The energy generated from the self-oscillation in the amplification process was suppressed, and the energy transfer efficiency during the amplification was increased effectively. Finally, a switchable output with wavelengths of 1064 nm and 532 nm was obtained. When the repetition frequency was 10 Hz, a sub-nanosecond laser output with a pulse width of 496.4 ps, a pulse energy of 561 mJ@1064 nm, 330 mJ@532 nm, an energy stability of 2% and a uniform spot were obtained.