Optical Parametric Chirped Pulse Amplification Gain Stability

This thesis presents detailed theoretical and experimental studies on gain stability of optical parametric chirped pulse amplification(OPCPA) system. The main achievement are summarized as following:1. The histories of ultra-short and ultra-intensity pulse laser development are reviewed. Discussions about the advantages and disadvantages of OPCPA, Ti:sapphire and Nd:glass systems are presented.2. A detailed numerical simulation and analytical calculation model of OPCPA are established. Some basic theories of OPCPA, such as, gain stability properties, phase matching, walk-off in space and time, etal, are elaborated. The gain property of OPCPA in BBO,LBO and KDP crystal is concluded and compared.3. The gain stability of OPCPA system is studied in small signal gain and gain saturation. Based on our analysis, better output gain stability in the case of strong saturated amplification can be achieved by elaboratively selecting the pump intensity, signal intensity and crystal length.4. In order to improve output gain stability, several methods are demonstrated as following. Firstly, the PPKTP crystal is designed to achieve saturated optical parametric amplification in the case of small signal. Secondly, two novel schemes are proposed and introduced to realize the precise timing synchronization of the pump and signal pulse in OPCPA such as the injected regeneration amplifier and spectrum time expanded telescope. Thirdly, a novel parametric amplifier technique is proposed to shape the pump pulse with better pulse curve and energy stability. Based on the OPCPA technique, a new scheme instead of the first stage amplifier of SILEX-1 laser facility was proposed and designed, through the numerical simulation and analysis, the output energy variation of SILEX-1 can be controlled in the range of 3%.5. In the case of combining the techniques of optical parametric amplifier with super-continuum spectrum generation, a novel concept to develop the high stable OPA system is demonstrated at the first time. There are many advantages ,such as, several milli-joule signal energy at 1053nm, extremely high contrast ratio within femtosecond, zero jitter time delay synchronization between 800-nm and 1053-nm pulse can be obtain directly. In our experiment, two LiNbO3 crystals of 60 × 60 × 15mm size were used, which was pumped by a 120-fs at 800-nm laser pulse, the maximum signal output energy reached 4.6-mJ with 1.19% energy stability(RMS) at 1053-nm, the corresponding energy conversion efficiency was 15%. The experiment also demonstrated the spectrum bandwidth of 65-nm could be attained.