A repetition rate of 2.3 GHz is achieved in a femtosecond Ti:sapphire laser. Pulses of 240 fs duration centred on 840 nm are produced from a simple 4-mirror laser cavity that incorporates a saturable Bragg reflector and operates at pump powers as low as 400 mW.
Stormont, B., Cormack, I. G., Mazilu, M., Brown, C. T. A., Burns, D., & Sibbett, W. (2003). Low-threshold, multi-gigahertz repetition-rate femtosecond Ti : sapphire laser. Electronics Letters, 39(25), 1820-1822. https://doi.org/10.1049/el:20031187