Font Size: a A A

Experimental Studies Of Optical Parametric Chirped Pulse Amplification

Posted on:2009-07-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:H Y WangFull Text:PDF
GTID:1118360272466041Subject:Optics
Abstract/Summary:PDF Full Text Request
A novel thesis and technique called optical parametric chirped pulse amplification(OPCPA) will be as a substitute for chirped pulse amplification(CPA), which generates ultrashort laser pulses with high-peak powers and a high prepulse contrast ratio.This thesis first summarizes the development and level of OPCPA technology,explores key technique based on the basic theory of OPCPA,builds the OPCPA system seeded by Ti:sapphire laser and a home-made Yb3+-doped self-starting passively mode-locked fiber laser separately,and studies detailedly the key issue involved in the OPCPA system.We summarize the main research works and the innovative results as follows:1.A detailed basic theoretical study of the optical parametric amplification process based on the theoretical model of typeⅠphase-matched BBO optical parametric chirped pulse amplifier was detailedly investigated.The theoretical treatment includes mainly coupled wave equation for OPCPA, crystal for optical parametric amplification,phase-matching principles and phase-matching types,the bandwidth and gain of optical parametric amplifier.2.The spatial properties of parametric fluorescence based on the amplification transfer function in a typeⅠphase-matched BBO crystal were detailed studied.The numerical simulation results demonstrate that the angular distribution parametric fluorescence is first emitted in a cone in a specific phase-matching angle zone and noncollinear angle zone,then in a ring in the other phase-matching angle zone and noncollinear angle zone always centered on the pump wave direction.3.Dispersion control of a broadband optical parametric chirped pulses amplification laser system is investigated.Firstly,Dispersion source of the OPCPA system is analyzed and discussed.Secondly,using the numerical method,the theoretical model of dispersion and the effects of high-order dispersion on signal pulses are presented in broadband OPCPA laser system. The numerical simulation results demonstrate that dispersion of pulse stretcher and phase change from signal pulse in amplifier is relatively great, dispersion of parametric crystal can be ignored,and that second-order-dispersion mainly controlled the pulse duration,the pulse SNR is effected by third-order-dispersion and fourth-order-dispersion.However, change of pulse frequency from dispersion is negligible.4.Theoretical and experimental study of Large-ratio(O|¨)ffner stretcher for OPCPA laser system was presented.Firstly,the key parameters of the output pulse duration of the pulse stretcher was discussed by use of the method of numerical simulation based on the more scientific way of the ray-tracing. Secondly,an(O|¨)ffner stretcher was setup experimentally.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.5.The OPCPA system seeded by Ti:sapphire laser source has been built.In this system,the single-passed architecture of the first OPA stage and 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.This scheme has a potential application for front-end amplification for petawatt-class laser system.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.6.The experimental study of the OPCPA system seed by fiber laser was demonstrated for the first time.Firstly,two stage single-passed OPA arrangement was used,high stability,great conversion efficiency,compact and omitting pulse stretcher OPCPA system was realized.A gain higher than 4.0×106,single pulse energy exceeding 6 mJ with fluctuations less than 2% rms,14 nm amplified signal spectrum and recompressed pulse duration of 525 fs are achieved.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 0.5%of the total output pulse energy,8 nm(FWHM)amplified signal spectrum are achieved.
Keywords/Search Tags:optical parametric amplification, parametric fluorescence, dispersion, (O|¨)ffner stretcher, fiber laser
PDF Full Text Request
Related items