Study Of A PZT Servo-controlled PCF Coupling Setup And A Digital Phase-Frequency Detector (PFD) For Femto-second Optical Frequency Comb

Firstly, a general description about the development of the optical frequency metrology is given in this paper. Secondly,comprehensive details about the theories of femto-second frequency comb and the NIM femto-second optical comb are introduced.And the system offset frequency f₀, one of the important parameters ofthe NIM femto-second optical comb,is deeply studied. Based on the work above, according to the hardness of accessing the system offset f₀, its low S/N ratio anddisturbance from the outside, a feedback system is designed in order to make compensation for the drop of its S/N ratio, by changing the position of the three-axis stage, on which the PCF fiber is located. In the condition of not locking the frequency of f₀,f₀ keeps a high S/N ratio for a longer time effientlly. Based on thecharacteristics of f₀. A digital PFD which is suitble for locking f₀ is made, the frequency stabillity of f₀ is in the level of formal system of Menlosystem.