An analog+digital phase-frequency detector for phase locking of a diode laser to an optical frequency comb

Optical phase locking of a diode laser to a mode of a femtosecond optical comb has been achieved with a system that combines the advantages of analog and digital phase detectors. Low noise and fast response are combined with a broad phase range and lock reliability. Details of the circuit are illustrated, and properties of different phase detectors in view of optical frequency measurements are discussed.