Fig. 1. Experimental setup of the high-power Kerr-lens mode-locked Yb:CYA laser. C1 and C2, concave mirrors with ROC of 300 mm; GTI1 and GTI2, Gires–Tournois interferometer mirrors with total dispersion of −1850  fs2 per bounce; C3 and C4, concave mirrors with ROC of 100 mm; M1, dichroic mirror; M2 and M3, flat mirrors with high reflectivity; OC, output coupler with transmittance of 2.5%.

Fig. 2. Output performances of the continuous wave (CW) and Kerr-lens mode-locked operations of Yb:CYA laser, respectively.

Fig. 3. Pulse characterization results of the KLM Yb:CYA laser. (a) CW (red) and mode-locked (blue) spectra, inset is the beam profile at the maximum average power of 1.5 W. (b) Measured intensity autocorrelation trace shown as black dashed while the fitted sech2 trace shown by red solid curve.

Fig. 4. Oscilloscope traces of the high-power Kerr-lens mode-locked pulse train in the time scales of (a) 10 ns/div, and (b) 4 μs/div, respectively.

Fig. 5. RF spectra of the Kerr-lens mode-locked Yb:CYA laser. (a) RF spectrum at the fundamental beat note with the resolution bandwidth of 1 kHz. (b) RF spectrum at 1 GHz wide-span range with the resolution bandwidth of 100 kHz.

Fig. 6. Summary of the sub-100 fs mode-locked lasers based on bulk Yb-doped crystals with watt-level average output power [1,46" target="_self" style="display: inline;">–6,8,12,13,22–26" target="_self" style="display: inline;">–26].