Nd:YAG Produces 53-mJ Green Light

Scott M. Aldis-Wilson

It may not be easy being green, but researchers at Mitsubishi Electric Corp.'s Advanced Technology R&D Center based in Amagasaki, Japan, have made the most of it. They have produced 53 mJ from a diode-pumped, intracavity frequency-doubled Nd:YAG laser. The results could pave the way to higher pulse energies while maintaining electrical efficiency.

Researchers have produced 53 mJ from a diode-pumped, intracavity frequency-doubled Nd:YAG laser. They also used the output of this configuration to produce 12 mJ of 266-nm light.

Susumu Konno, a researcher on the project, said that the team has been working on the frequency-doubled laser system for approximately two years, but that it had spent more than five years developing the pump configuration. The setup features four diode modules for each of two Nd:YAG rods. Each module comprises four 60-W, 808-nm quasi-continuous-wave laser diodes, with each module rotated 22.5° around the optical axis from the others. A LiB₃O₅ crystal in one leg of the resonator supplies second-harmonic generation.

The 53-mJ, 532-nm beam exhibits a 6 percent electrical-to-optical efficiency at a repetition rate of 1 kHz. This efficiency is comparable to that achieved by lower-energy sources of green light.
The work also yielded the highest ultraviolet pulse energies obtained from such equipment at repetition rates greater than 1 kHz. The researchers focused the output of the green laser into a 15-mm-long CsLiB₆O₁₀ crystal that they kept in an oven at 140 °C, producing 12 mJ of 266-nm light.

The results provide important data about solid-state sources of green light, which are known for providing reliable and efficient ultrashort pulses. The lasers are used for applications in materials processing, and the researchers hope to use the setup as a pump source for Ti:sapphire lasers.