Experimental research on measuring the fine structure of long pulse in time domain by synchronized ultrashort pulse

We propose a method of measuring the fine structure of a long pulse in time domain by a synchronized ultrashort pulse, in which the basic principle is the cross-correlation interaction between the long pulse and the ultrashort pulse in a nonlinear crystal. After a theoretical analysis on the principle and resolution, as an example, the fine structure of a picosecond Nd:YLF laser pulse is characterized by a synchronized femtosecond pulse experimentally. Further, the effect of group velocity mismatch on measurement results is discussed.