Research Of High-temporal-contrast Femtosecond Regenerative Amplifier

Since the 1980-s,advanced in femtosecond laser technologies has led to tremendous progress in high field science.Thanks to the advent of the technique chirped-pulse amplification(CPA),progress in laser amplifier made it possible to produce pulses in high power with a duration as short as several femtoseconds.Construction of an ultrafast regenerative amplifier and methods to improve the temporal contrast are discussed in this dissertation.The regenerative amplifier contains a pulse stretcher,a Faraday isolator,a laser cavity,a Saturable absorber,a delay generator and a compressor.This design will require the two levels of originally to get high contrast ration laser pulse,now it can be achieved in the level of amplification,which greatly saves space and cost.Oscillator provide seed pulses.Pulses are then stretched by a grating-based stretcher to prevent nonlinear effects such as self-focusing,self-phase modulation and prevent optical element are damaged.The regenerative amplifier utilizes a ring cavity to support large mode size and suppress amplifier spontaneous emission(ASE).A Pockels cell is used to feed and extract pulses in the cavity.The seed pulse is amplified in laser cavity,then a saturable absorber for filter in order to enhance contrast ration.A amplified pulse is stretched,secondary amplified and compressed.This dissertation is divided to several parts:firstly,the progress of the laser technology and relevant application is introduced.Secondly,the working principle of the laser system is discussed.Thirdly,the arrangement,execution and optimization procedure is discussed.Fourthly,analyzation of experiment results is present.Finally,a conclusion and improvements of experiment are discussed.