Using a modified ABCD-matrix approach accounting for nonlinear refraction in active medium

we determined the ranges of cavity parameters providing a mode-locking of Yb:KYW-laser in usual z-fold cavity configuration. Taking the cavity parameters providing a most efficient mode locking and based on fluctuation model

we performed a numerical simulation of laser operation. We used for our calculations the side-band pump power of 6 W at 982 nm with 1 cm×50 μm beam cross section in active medium and the length of 1 cm for KYW crystal. Calculations showed that self-starting operation is possible with these parameters and dispersion compensation allows for bandwidth-limited ultra-short pulse generation. The shortest pulse duration was determined to be approximately 200 fs with self-starting build-up time of 130 μs. Such a built-up time is comparable and even shorter than that one for the lasers with semiconductor saturable absorbers. The region of negative dispersion provided by prism pair where a stable ultra-short pulse generation takes place was determined to

be (-17 000~42 000) fs

2

.