[摘要]:Mode-locking at repetition rate of 70 MHz with 115 fs spectral-limited pulses was obtained in Yb(3+):KY(WO(4))(2) laser with low loss saturable absorber. Special design and manufacture of saturable absorber incorporating InGaAs quantum wells separated by nanostructured barriers and a wide band total reflector resulted in the semiconductor saturable absorption mirror (SESAM) with short recovery time and low non-saturable losses. This permitted to receive average output power of 1.57 W in mode-locking regime close to 1.62 W power in continuous-wave regime.