This paper describes a femtosecond laser based on Yb:KYW with direct pumping by a semiconductor injection laser. The Yb:KYW laser crystal was pumped longitudinally with the radiation of an InGaAs semiconductor injection laser with fiber output of the radiation. The spatial structure of the radiation of the semiconductor laser was reshaped by a lens-based optical system in order to maximize its power concentration in the volume of the laser medium. Femtosecond pulses were generated in the longitudinal mode-locking regime by using a semiconductor saturable absorber. The generator's mean power exceeded 1W at the central wavelength of 1043nm, with a pulse about 90fs wide. The master oscillator thus developed can be used both as a self-contained source of femtosecond light pulses and as a priming source for femtosecond laser amplifier systems.
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