Real-time ultrashort laser pulse compression based on single-shot spectrogram

Abstract

Optical dispersion would affect ultrashort laser pulse duration and thus decrease energy concentration. The instantaneous peak power will be reduced and affect the nonlinear optical absorption. To detect and compensate the optical dispersion dynamically, we have integrated the real-time ultrashort pulse measurement based on direct optical-dispersion estimation by spectrogram (DOES), the DOES could be used to find the group delay dispersion (GDD) from single shot spectrogram with fast and accurate computation time. the ultrashort pulse compensation system consist of a blazed grating and deformable mirror (DM). The GDD is used to drive the DM compensation by digital PI controller implemented on field programmable gate array (FPGA). The compression system could be operated at 100 Hz in real-time and is implemented to multiphoton excited fluorescence microscopy (MPEFM) system. The experimental result shows the static and dynamic dispersion could be compensated in 50 ms, and the overall nonlinear excited efficiency could increase to 1.4-fold, which is the theoretical limit based on the current setup.