Dielectric Superlattice Materials To Improve The Bandwidth And Stability Of Optical Parametric Amplification

In 1990s,the generation of chirped pulse amplification fastened the research of ultra-fast and ultra-peak-power lasers.The further development of these systems to higher powers would require the generation of shorter pulses.However CPA has already reached its practical limit in pulse duration,as determined by the gain narrowing effect within the amplifier medium.These limitations are largely removed using a novel technique called optical parametric chirped pulse amplification(OPCPA).A rapidly evolving and exciting field appeared in the current development of OPA using dielectric superlattices,after the development of electric field poling method.The dielectric superlattices has a large nonlinear coefficient,long interaction distance,compact configuration,especially it's engineerable property,make it a promising technique for optical parametric amplification.In this paper,in order to meet the demand of OPA to bandwidth and stability,taking the advantage of dielectric superlattices,we make an intensive study of quasi-phase-matched(QPM)optical parametric amplification to improve the bandwidth and stability of optical parametric amplification.Firstly,the conception and history of dielectric superlattices is introduced,the theory and advantages of quasi-phase-matching are summarized.A series of experimental research was developed and designed a variety of structure to improve the bandwidth of nonlinear frequency conversion.Coupled wave equation was simplified and quasi-phase-matched optical parametric amplification theoretical model was established.The theory of QPM was explained form the two aspects of coupled wave equation and reciprocal vector.Birefringence-phase-matching (BPM)and quasi-phase-matching(QPM)techniques were compared.The property and use of a variety of QPM crystals were compared.Finally the development direction of QPM techniques was summarized.The most mature technology of dielectric superlattices fabrication is electric field poling.History and method of electric field poling is summarized.According to the domain-invert theory and poling method,the reason and types of domain errors are investigated.Fabrication errors are categorized into period error and duty cycle error.The value of errors in fabricated sample is measured.Calculated the impact of the two kinds of errors to the efficiency and bandwidth of OPA.The following conclusions were made; efficiency is mainly influenced by duty cycle errors,and the bandwidth would not be improved by the errors. The relation of crystal period and signal wavelength was calculated and illustrated how the chirped period supperlattices improve the bandwidth and stability of OPA.Chirp factor of suppeflattices was defined.Estimated the relation between pump,signal,temperature bandwidth and chirp factor.Established the equation and algorithm of QPM-OPA,calculated the gain and bandwidth of chirped PPKTP,summarized the design principle of chirped supperlattices.Calculated the stability of chirped period QPM-OPA under multiple factor impactions.Designed temperature gradient and fanned supperlattices to realize supperlattice's chirp.Deduced the conversion relation between chirp factor and temperature gradient, calculated fanned grating's chirp principle.Flatten the bandwidth of OPA by using fanned grating.Investigated the impaction of pump fluctuation to output stability,minimized this impaction by use of engineered supperlattices.Finally simulated two-dimensional QPM-OPA by Split-Step Fourier method.Designed and fabricated the temperature control device and measured the parameters of it.Designed and fabricated uniform period PPLN and PPLT supperlattices.QPM-SHG was build and beam parameters were measured.SHG experiment was carried out,efficiency and temperature bandwidth is measured.The theory and experimental results were compared.