High-efficiency nanosecond green laser based on extra-cavity second-harmonic generation of a Nd:YAG MOPA system

• Published in: IEEE photonics journal 2023-10, Vol.15 (5), p.1-6
• Main Authors: Liu, Hua-Yu, Zhou, Zi-Han, Bian, Qi, Bo, Yong, Kou, Yang, Yuan, Lei, Cui, Da-Fu, Peng, Qin-Jun
• Format: Article
• Language: English
• Subjects: Acousto-optics; Amplifiers; Crystals; Efficiency; extra-cavity frequency doubling; Green laser; high-efficiency; Infrared lasers; Laser applications; Laser beams; Lasers; Lithium; Master oscillator/power amplifier; Mirrors; Nd:YAG MOPA; Neodymium lasers; Oscillators; Power lasers; Pulse duration; Q factors; Q switched lasers; Second harmonic generation; Semiconductor lasers; YAG lasers
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2023.3309390

A high infrared-to-green conversion efficiency laser is demonstrated by extra-cavity frequency-doubling of a master oscillator power amplifier (MOPA) laser. The oscillator is a diode-side-pumped acousto-optic Q-switched Nd:YAG laser at 1064 nm with an average output power of 38.2 W and a beam quality factor M 2 = 1.15, operating at a 2 kHz repetition rate and a 38.3 ns pulse duration. After a dual-rod double-pass amplifier, the fundamental seed power is amplified to 89.4 W with the beam quality of M 2 = 1.41 and pulse duration of 56.4 ns. Using a type Ⅰ lithium triborate (LiB 3 O 5 , LBO) crystal for second-harmonic generation (SHG), an average power of 67.4 W at 532 nm is generated with a beam quality factor of 1.31, operating at 41.8 ns of pulse duration. The corresponding frequency doubling efficiency is as high as 75.4%, which is, to the best of our knowledge, the highest doubling efficiency reported ever for 532 nm source by an extra-cavity SHG laser system.