Method and device for time synchronization of picosecond and subpicosecond laser pulses

摘要

The method and device for the time synchronization of picosecond and sub-picosecond laser pulses by means of a feedback loop based on measurement of the relative delay of the pulses of the signal and pump laser beam, using their interaction in a nonlinear medium, where the partial laser beams intended for synchronization control are uncoupled (1a/1b) from the primary laser beams immediately before entering the interaction which is sensitive to pulse synchronization (A-B). The polarization plane of the uncoupled beams (2a/2b) is adjusted with regard to the subsequent optical elements and one of the polarization components of one of the partial beams is delayed in a fixed and defined manner (3τ). Two polarization components of both partial beams, corresponding to the selected type of OPA interaction, are then together and synchronously directed to at least one anisotropic nonlinear medium exhibiting the OPA phenomenon (4x/4y) in which the partial signal beam is amplified and the idler wave is generated. The measuring element then measures and compares the individual intensities of both pulse polarization components of the signal wave and/or idler wave (5x/5y) and based on this evaluation, the feedback loop for the synchronization is implemented (A~B). From a laser oscillator (1) a chirped femtosecond probe pulse (8) is derived as well as pump pulse (9). The jitter stabilisation between these two pulses is performed with the help of a controlled delay line (4) and the pump pulse is amplified in a subsequent regenerative amplifier (2). Part of the amplified pump pulse (10) and the probe pulse is directed to a OP-CPA (3). The remainder is directed to a jitter stabilisation system (6). This system comprises a MZI for control of the ratio of the two polarisation components of the amplified pump pulse which are subsequently overlapped with the probe pulse in an OPA and the intensity of the generated idler is used as a parameter to stabilse the relative delay between the amplified pump pulse and the probe pulse by control of the pump pulse delay line (4).