500 kHz OPCPA delivering tunable sub-20 fs pulses with 15 W average power based on an all-ytterbium laser.

An optical parametric chirped pulse amplifier fully based on Yb lasers at 500 kHz is described. Passive optical-synchronization is achieved between a fiber laser-pumped white-light and a 515 nm pump produced with a 200 W picosecond Yb:YAG InnoSlab amplifier. An output power up to 19.7 W with long-term stability of 0.3% is demonstrated for wavelength tunable pulses between 680 nm and 900 nm and spectral stability of 0.2%; 16.5 W can be achieved with a bandwidth supporting 5.4 fs pulses. We demonstrate compression of 30 µJ pulses to sub-20 fs duration with a prism compressor, suitable for high harmonic generation.

Temporal and spatial effects inside a compact and CEP stabilized, few-cycle OPCPA system at high repetition rates.

We present a compact and ultra-stable few-cycle OPCPA system. In two non-collinear parametric amplification stages pulse energies up to 17 µJ at 200 kHz repetition rate are obtained. Recompression of the broadband pulses down to 6.3 fs is performed with chirped mirrors leading to peak powers above 800 MW. The parametric amplification processes were studied in detail employing (2 + 1) dimensional numerical simulations and compared to experimental observations in terms of spectral shapes, pulse energy, spatial effects as well as delay dependent nonlinear mixing products. This gives new insights into the parametric process and design guidelines for high repetition rate OPCPA systems.

All-fiber ytterbium femtosecond laser without dispersion compensation.

We report on an all-fiber femtosecond ytterbium laser without dispersion compensation consisting of all-normal dispersion fibers. Mode-locking was achieved by nonlinear polarization evolution in combination with additional amplitude modulation generated by a fiber-based spectral filter. The generated pulses were highly chirped and had a maximum pulse energy of 1.8 nJ. The output pulse duration was 7.6 ps and could be dechirped to 179 fs.

Sub-60-fs ytterbium-doped fiber laser with a fiber-based dispersion compensation.

We present a mode-locked ytterbium fiber laser with a higher-order mode fiber compensating the group-velocity dispersion and partially the third-order dispersion of the single-mode fiber at a wavelength of 1 microm. The generated pulses had an energy of 0.5 nJ and could be dechirped externally to a pulse duration of less than 60 fs. The power spectrum shows a spectral full width at half-maximum of 57 nm.

All-fiber similariton laser at 1 mum without dispersion compensation.

We report on an all-fiber femtosecond Ytterbium laser without dispersion compensation operating in the similariton pulse regime. The oscillator was mode-locked with a saturable Bragg reflector along with nonlinear polarization evolution. A pulse energy of 0.8 nJ was achieved with a pulse duration of 10 ps. The pulses could be externally dechirped to 627 fs which was within 8.7% of the Fourier transform limited pulse duration. The ealized oscillator combines compact size, high stability and alignment-free operation.