Ultrafast VECSELs are compact pulsed laser sources with more flexibility in the emission wavelength compared to diode-pumped solidstate lasers. Typically, the reduction of the pulse repetition rate is a straightforward method to increase both pulse energy and peak power. However, the relatively short carrier lifetime of semiconductor gain materials of a few nanoseconds sets a lower limit to the repetition rate of passively modelocked VECSELs. This fast gain recovery combined with low pulse repetition rates leads to the buildup of multiple pulses in the cavity. Therefore, we applied an active multipass approach with which demonstrate fundamental modelocking at a repetition rate of 253 MHz with 400 mW average output power in 11.3 ps pulses. Tropper, "A passively mode-locked external-cavity semiconductor laser emitting 60-fs pulses," Nat. Photonics 3(12), 729-731 (2009). 8. P. Klopp, U. Griebner, M. Zorn, and M. Weyers, "Pulse repetition rate up to 92 GHz or pulse duration shorter than 110 fs from a mode-locked semiconductor disk laser," Appl. Phys. Lett. 98(7), 071103 (2011). 9. P. Klopp, F. Saas, M. Zorn, M. Weyers, and U. Griebner, "290-fs pulses from a semiconductor disk laser," Opt.Express 16 GHz passively mode-locked surface-emitting semiconductor laser with 100 mW average output power," IEEE J.