ИСТИНА

Precise synchronization of mode-locked pico- and femtosecond lasers integrated in technological and research complexes is a crucial issue for many applications. Jitter of output optical pulse respective to periodic reference signal in continuous wave (cw) lasers can be effectively suppressed up to femtosecond level by means of feedback controlled cavity adjustment. Cross modulation approach gives even more synchronization accuracy. However, high-peak-power laser systems with precise optical synchronization option based on cw oscillators are overly complex and expensive for most practical applications. High-peak-power mode-locked picosecond lasers with pulsed (qcw) pump are applicable for such fields as high precision laser micromachining, soft X-ray generation, laser photo injection for electron accelerators, routine time-resolved spectroscopic measurements, laser ranging etc. Systems based on pulsed oscillators may have definite advantages in comparison with cw ones, providing high pulse energy at the oscillator output, better efficiency of energy consumption, lower thermal loading, relative simplicity and compactness. At the same time, typical duration of generation process development in each laser shot ~10-5 s is too short both for phase detector operation and for cavity adjustment which are convenient techniques for cw lasers. Ultrashort pulse goes several hundreds roundtrips during generation process development in each pump pulse. Its time position is defined by several factors such as amplification in active element, passive mode-locking based on semiconductor absorber mirror, action of negative feed-back and active modelocking by means of electrooptical amplitude modulator. Driving active mode-locking signal through rapid phase changing makes it is possible to control precisely laser optical output time position in arbitrary delay range. Minimal jitter is mainly determined by width of “temporal transparency window” which is formed by cumulative action of the above factors in the oscillator. In the present paper, we discuss experimental and modeling results on jitter decreasing in picosecond pulse-diode-pumped Nd:YAG and Nd:YLF lasers within output pulse duration level of several tens of picoseconds. The work was supported by Russian Foundation for Basic Research (10-02-01277-a)