Double-Arched LDA Stagger-Pumped Electro-Optic <Emphasis Type="Italic">Q</Emphasis>-Switched Nd:YAG Green Laser Using KTP Double-Crystal Extracavity Frequency Doubling

We develop a laser utilizing second harmonic generation that exhibits both high single-pulse energy and high beam quality. The system starts with a double-arched laser-diode-array stagger-pumped electro-optic Q-switched Nd:YAG with a thermal lensing compensated convex-concave resonator. The 1,064 nm output beam is then frequency doubled in an extracavity KTP double-crystal assembly that offsets birefringence walk-off. We obtain a maximum single-pulse energy of 72.7 mJ at 532 nm with 176 mJ at 1,064 nm. The corresponding optical-to-optical conversion efficiency is 41.3%, and the pulse width is 9.2 ns at a repetition rate of 20 Hz. The beam quality factor M² is 1.83 in both horizontal and vertical directions at the maximum output energy, and the energy stability is better than 3% across half an hour.