Third harmonic of Nd:YLF laser creates more than seven watts ultraviolet output
A lamp-pumped Q-switched Nd:YLF laser with 15.5 W of output at 1.053 µm was used by scientists at Photonics Industries International (Stony Brook, NY) to generate 7.1 W of UV output at 351 nm. Intracavity second- and third-harmonic generation with lithium triborate produced 5 and 7.1 W at repetition rates of 1 and 3 kHz, respectively. Applications engineer Ching Fong claims this is the highest UV power reported, with an IR-to-UV conversion efficiency of 46%. Fong says the improved efficiency is due in part to better crystal quality and the intracavity generation. Laser machining with UV light gives cleaner edges than those obtained from visible or IR machining, and the TEM00 beam profile allows drilling of sub-micron-size holes. Applications for the UV output include polymer machining, circuit-board cutting, and hole drilling on boards with multilayer substrates.