We report on mode locking of a bulk Cr:YAG laser by using a transmission-type single-walled carbon nanotube saturable absorber. Stable and self-starting laser operation in the picosecond and femtosecond regimes is obtained at wavelengths around 1.5 microm. Tunable transform-limited sub-100 fs pulses are generated at a repetition rate of 85 MHz with an output power up to 110 mW.