In this paper we present a passively mode-locked laser oscillator based on Yb:LPS crystal with a single-mode laser diode as a pumping source. The pulsed operation was initiated with a semiconductor saturable absorber mirror. The pulses were as short as 90 fs, which, to the best of our knowledge, is the shortest pulse duration obtained from a Yb:LPS laser to date. The central emission wavelength was 1050.6 nm and it was 16.2 nm broad. The average power was equal to 82 mW corresponding to a peak power of 7.8 kW.