Building a frequency-stabilized mode-locked femtosecond laser for optical frequency metrology

We have built a frequency-stabilized mode-locked (ML) femtosecond (fs) Ti:Sapphire laser designed to serve national frequency metrology in Taiwan. We find that the self-referencing technique can be realized by single-beam f-2f as well as two-beam f-2f interferometers with the proper choice of photonic crystal fibers. The stabilized repetition frequency and offset frequency of the laser is found to have a one standard deviation of fluctuation of 0.3 and 1.3 mHz, respectively in a 1-s gate time. The frequency comb created by the ML fs laser is used to measure the frequencies of stabilized single-frequency lasers.