We demonstrate a novel compact femtosecond Ti:sapphire laser system operating at repetition rates from 10 kHz to 4 MHz. The scheme is based on the combination of a broadband cavity-dumped oscillator and a double-pass Ti:sapphire amplifier pumped by a low-noise cw solid-state laser. Amplified pulses with an extremely smooth spectrum, a duration of only 12 fs, and less than 0.25% rms fluctuation are generated in a beam with M<sup>2</sup> < 1.2 . A maximum pulse energy of 210 nJ and an average output power of as much as 720 mW are achieved. This output energy is sufficient to generate a stable continuum in a sapphire disk.
© 2003 Optical Society of America
R. Huber, F. Adler, A. Leitenstorfer, M. Beutter, P. Baum, and E. Riedle, "12-fs pulses from a continuous-wave-pumped 200-nJ T:sapphire amplifier at a variable repetition rate as high as 4 MHz," Opt. Lett. 28, 2118-2120 (2003)