Theoretical And Experimental Study Of Ultrashort Pulse Laser Amplification

Ultrashort pulse amplification, including chirped pulse amplification (CPA) and optical parametric chirped pulse amplification (OPCPA), has been becoming one of the hot researches in the field of ultrashort pulse laser technology because ultrashort and ultrahigh intensity pulse laser has important applications in high field physics, such as X-ray laser, ICF, laboratory astrophysics, laser particle accelerator, and so on. Since Ti:sappire owns many great properties, chirped pulse amplification based on Ti:sappire makes rapid technical progress and many developed countries have built up 100TW-grade Ti:sappire ultrashort and ultrahigh pulse laser system. Optical parametric chirped pulse amplification gets great academic interests because of its many merits.In this paper, the experimental part is the sum-up of theoretical and experimental studies on a 20TW Ti:sappire femtoscecond high-intensity laser system while author worked in the Research Center of Laser Fusion of CAEP, which includes oscillator, regenerative amplifier, multi-pass amplifier, stretcher, compressor and synchronization system. The theoretical part mainly refers to studies of optical parametric chirped pulse amplification. We analyze some basic theories of OPCPA, such as phase matching, parametric bandwidth, walk-off in space and time, gain property and so on, and compare the basic properties of BBO, LBO and KDP. We also use fourth Runge-Kutta method simulate the OPCPA process in the case of considering signal and pump temporal profile and phase mismatching and get gain and spectra properties at different pump temporal profile. The results show that there is gain narrowing when pump is Gaussian temporal profile and it's pulse width close to signal's and that the spectrum extended in the case of saturated amplification when pump is near top-hat temporal profile.