The Bivoj team, led by Dr. Martin Divoky, and Dr. Jonathan Phillips from STFC have successfully demonstrated high energy second harmonic generation (SHG) at 515 nm with a nonlinear LBO crystal at Bivoj laser system. The SHG experiment was performed utilizing the nanosecond Bivoj laser system at 1030 nm with an output energy of 5.9 J at 10 Hz. The aperture and the length of the LBO crystal were 25 mm and 13 mm, respectively. Figure below (in downloads) shows the long-term SHG output energy (green line) and the total fundamental energy (thick red line). Over an extended period of 110 minutes, the conversion efficiency remained stable with a SHG energy stability of 0.8% rms.
Future plans include third harmonic generation (THG) and upgrade of laser beam distribution system for propagation of fundamental and SHG beams to the target chambers. This will greatly extend spectrum of experiments that can be performed by user on Bivoj laser system. Those experiments can involve processing of materials by high energy with this specific wavelength. A wide range of materials have a significantly greater absorption of 515 nm laser radiation and this allows us to efficiently process non-ferrous metals such as copper or aluminum alloys. Likewise, this wavelength is little absorbed by water, so we can conduct experiments under water for specific industrial applications. Very interesting application is also the possibility of testing optical components in this expanding field of green lasers usage. We anticipate that the second harmonic beam will be available to users from 2020.