From relative to absolute: optical phase measurement and control in ultrashort pulses

Summary form only given. A phase stabilized frequency comb spanning an entire optical octave (>300 THz) has been established, leading to a single step, phase coherent connection between the optical and radiofrequency spectral domains. The precision comb can also serve as an accurate gear-box to transfer the oscillatory information of a laser stabilized by a high quality optical transition down to the microwave/rf domain, thereby establishing a simple optical atomic clock. We present one of the systems based on an optical transition of iodine molecules, providing an rf clock signal with a frequency stability comparable to that of an optical standard, and that is superior to almost all conventional rf sources. To realize a high-power CW optical frequency synthesizer, a separate widely tunable single-frequency cw laser has been employed to randomly access the stabilized optical comb and lock to any desired comb component.