RESUMEN
A 1064-nm femtosecond fiber chirped pulse amplification (FCPA) laser system based on a single-stage double-pass Yb-doped rod-type photonic crystal fiber (PCF) amplifier was demonstrated with a pulse repetition rate of 500 kHz, which was specially designed for expected conversion efficiency enhancement of a 10.8 eV source. With a series of Yb:fiber power amplifiers, the average output power was boosted to approximately 35 W. Further, using a transmission gratings-based pulse compressor, an average output power of 27.5 W was achieved, corresponding to a pulse energy of 55 µJ and a compression efficiency of 78.6%. The shortest pulse duration was optimized to be 204 fs, which was also accompanied by obvious pedestal. A pulse duration of 336 fs was also obtained when the pulse quality was at a top priority. To the best of our knowledge, this is the first demonstration of high-repetition-rate high-pulse-energy 1064-nm, instead of 1035-nm, femtosecond laser, based on commercially available Yb-doped rod-type PCF amplifier.
RESUMEN
A widely wavelength tunable mode-locked Yb-doped fiber oscillator based on nonlinear amplifier loop mirror (NALM) is reported, in which only a piece of short (â¼0.5 m) single-mode polarization-maintaining (PM) Yb-doped fiber is employed, instead of the frequently used long (a few meters) double cladding (DC) fiber in previous papers. Experimentally, the center wavelength can be consecutively tuned from 1015 to 1105â nm by tilting the silver mirror, corresponding to a tuning range of 90â nm. To the best of our knowledge, this is the broadest consecutive tuning range in Yb:fiber mode-locked fiber oscillator. In addition, the mechanism of wavelength tuning is tentatively analyzed and attributed to the combined action of the spatial dispersion induced by a tilting silver mirror and the limited aperture in the system. Specific to the wavelength of 1045â nm, the output pulses with 13-nm spectral bandwidth can be compressed to 154 fs.