  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 microjoule
pulses to sub-20 fs duration with a prism compressor, suitable for high
harmonic generation.
