Fig. 1. Experimental setup of the blue LD-pumped Ti:sapphire oscillator. A 455 nm LD was used with a beam shaping system (L1, L2, and L3) as the pump source. The lens L4 focused the pump into a Ti:sapphire crystal, with the pump spot as shown in the inset. Curved double-chirped mirrors DCM1 and DCM2, flat double-chirped mirrors DCM3 and DCM4, output-coupling mirror OC, and prism pair P1 and P2 formed the laser cavity. Chirped mirrors CM5 and CM6 and a pair of wedges were used for extra-cavity dispersion compensation.

Fig. 2. (a) Reflectivity of the mirrors in the cavity. (b) Round-trip GDDs of the Ti:sapphire crystal, seven DCMs, prism pair, air, and their total sum.

Fig. 3. Pulse profiles of the LD-pumped Ti:sapphire oscillator. (a) Mode-locking spectrum. Inset shows the FTL pulse in the time domain. (b) IAC trace of the pulse (blue curve), and an envelope of a theoretical sech2 pulse of 9.8 fs (red curve).

Fig. 4. Pulse profiles after adjusting the prism insertion. (a) Mode-locking spectrum. Inset shows the FTL pulse in the time domain. (b) IAC trace of the shortest pulse generated from the Ti:sapphire oscillator (blue curve) and theoretical IAC envelope of a sech2 pulse of 8.1 fs (red curve).

Fig. 5. RF spectra of the 8.1 fs Kerr-lens mode-locked Ti:sapphire laser, with an RBW of 1 kHz. The inset shows the RF spectrum in the 1 GHz range with a 100 kHz resolution.

Fig. 6. Power stability of the single LD-pumped Kerr-lens mode-locked Ti:sapphire oscillator over 3 h.