Modelocked chromium-doped YAG laser offers ultrafast source
A novel three-mirror cavity may speed development of ultrafast Cr4+:YAG lasers for telecommunications test sources, spectroscopy, and other applications. Members of the Femtosecond Optics Grou¥at Imperial College of Science and Technology (London, England) reported a very compact, high-repetition-rate, Kerr-lens modelocked-cavity design that is simple to align and can be pumped by either a Nd:YVO4 or a diode-pumped ytterbium-doped fiber laser emitting at 1060 nm. Strong thermal lensing of Cr4+:YAG has made previous cavity designs difficult to align. The laser cavity contains a plane-Brewster-angled 20-mm-long Cr4+:YAG cylindrical crystal mounted on a copper block that is cooled to approximately 20°C. The plane surface was coated for high transmission at the pum¥wavelength and high reflection at the laser wavelength. Two adjustable mirrors controlled the repetition rate and enabled modelocking. The femtosecond-pulse output was tunable from 1505 to 1550 nm, with single-beam modelocked average output powers as high as 280 mW and repetition rates u¥to 1 GHz.
