Pulse Picker for Generating Femtosecond Radiation with a Selectable Carrier-Envelope Phase

A pulse picker has been developed to obtain a of femtosecond pulse sequence with controlled carrier-envelope phase is demonstrated. Of all possible trains, the carrier-envelope phase could be selected with a discreteness of 2.88 degrees. The repetition rate of such trains was 2 MHz, that is, every 125th pulse was extracted from the original sequence of pulses. The characteristics of the developed pulse picker that can operate at frequencies of 0.5–100 MHz made it possible to reduce the requirements for the accuracy of setting the selector phase relative to the phase of the original pulse train. The pulse picker makes it possible to obtain at the modulator output a “pure” femtosecond pulse train in a sufficiently wide range of the control signal phase tuning. A discreteness of setting the phase shift between the envelope and carrier can be reduced by increasing the ratio of the carrier frequency of the femtosecond radiation and the carrier-envelope offset.