Study Of The Optical Parametric Chirped Pulse Amplification

Optical parametric chirped pulse amplification (OPCPA) is widely used in intense field physics, high energy physics, which was originally proposed and demonstrated by Dubietis et al in 1992 The OPCPA technique has some significant advantages over other schemes such as high gain per single pass, a broad gain bandwidth, a high output beam quality, a low heat deposition and a small B integral. So the OPCPA is an alternation of the for-end source of the terawatt and peterwatt system.The main research works and innovations of this thesis are summarized as followed:1. A detailed basic theoretical study of the optical parametric amplification process was detailedly investigated. The theoretical treatment includes mainly coupled wave equation for OPCPA, phase-matching principles and phase-matching types, the bandwidth and gain of optical parametric amplifier.2. A novel ultra-broad bandwidth optical parametric amplification approach is investigated in this dissertation for the pump pulse with broadband. Using pre-chirp controlling,the phase-matching condition is satisfied in a ultra-broadband signal spectral range.3. A novel double-pass optical parametric chirped pulse amplifier is demonstrated.The signal is double-pass amplified in a nonlinear crystal by a long pump pulse and the signal and pump pulses of each pass were complete phase matched in the plane which has the maximum of the effective nonlinearity. By this system, the match of the signal and pump in the time is obviously increased and the superfluorescence is suppressed.4. An OPCPA system based on the Ti:sapphire femtosecond oscillator has been theoretical and experimental study. Firstly, theoretical and experimental study of Large-ratio ?ffner stretcher for OPCPA laser system was presented. Through appropriate optimization of the four parameters, expansion of 30 fs pulses to 545 ps with free aberration and a stretching ratio of 18,167 have been experimentally demonstrated. Secondly, A new double-passed architecture of the second OPA stage was demonstrated. By use of the double-passed architecture, on the one hand, this scheme efficiently increases the conversion efficiency, on the other hand, it remarkably decreases the uncompressible background arose from the parametric fluorescence. The net total gain higher than 3×107, single pulse energy exceeding 3 mJ with fluctuations less than 3% rms, 30 nm(FWHM) amplified signal spectrum and recompressed pulse duration of 82 fs (FWHM)are achieved.5. An OPCPA system based on an Yb3+-doped passively mode-locked fiber laser has been theoretical and experimental study. Firstly, using two stage single-passed OPA arrangement, a gain higher than 4.0×106, single pulse energy exceeding 6 mJ with fluctuations less than 2% rms, recompressed pulse duration of 525 fs are achieved. This system is high stability, great conversion efficiency, compact. Secondly, single stage double-passed OPA architecture was utilized. This scheme efficiently increases the transfer efficiency, and remarkably decreases the parametric fluorescence. The net total gain higher than 2×106, single pulse energy exceeding 2 mJ with fluctuations less than 2% rms, parametric fluorescence less than 1% of the total output pulse energy, 8 nm (FWHM)amplified signal spectrum are achieved.6. An OPCPA system based on an Yb3+-doped passively mode-locked interference pulse fiber laser has been theoretical and experimental studied. The overall net gain of the two-stage OPA reached 1.1×107, corresponding to the final output energy of 11mJ with fluctuations less than 1%. The superfluorescence energy is suppressed to 1% of the total output pulse energy. This scheme efficiently increases the transfer efficiency, and remarkably decreases the parametric fluorescence. The fiber laser showed the excellent long term stability under the temperature stabilized ultra-clean environmental condition, and the mode-locking operation could be hardly influenced by the external environment. By which, the stablity of the OPCPA system is increased.