Opt. Express 25, 12469–12477 (2017)

Although they are convenient and more compact, diode-pumped Ti:sapphire lasers tend to suffer from pump-induced loss. Now, Sterling Backus and co-workers from the USA have found a fix in the form of a single diode-pumped Kerr-lens mode-locked Ti:sapphire laser. A 465-nm diode laser with a lifetime of 10,000 hours and an output power of up to 4 W was used to pump a Ti:sapphire crystal. By using an aspheric lens and cylindrical telescope, the beam diameter of the diode laser was shaped to become 56 μm in the vertical direction and 118 μm in the horizontal direction. It is estimated that 70% of the pump light was absorbed in the 4.75-mm-long crystal. The Ti:sapphire laser mode-locked easily, producing 15.2 fs pulses, with no evidence of mode-locking instabilities. When the power of the diode laser was held constant at 3.1 W, the output power from the Ti:sapphire laser was 173 mW over 600 hours with a 0.33% root-mean-square stability. Contamination of the Ti:sapphire crystal, which is often evident on this timescale using traditional TEM00 green pump lasers, did not occur. The spatial mode quality of the output mode-locked beam was excellent with a beam quality factor M2 of 1.02 in the horizontal direction and 1.17 in the vertical direction.