Theoretical And Experimental Study Of High Repetition Rate Ultra-broadband Optical Parametric Amplification Technology

High repetition rate and high energy ultra-short laser pulses have important applications in ultrafast time-resolved spectroscopy,probing of ultrafast processes, nonlinear optics and intense field physics.Recent developments in these fields have increased the demand for extremely short pulse laser that can approach sub-5-fs even single cycle laser pulses.The ultra-broadband optical parametric amplification is a significant approache to obtain such pulses.In this dissertation we investigate the high repetition rate and ultra-broadband optical parametric amplification(OPA).The main achievements are listed as follows:1.The general theoretics of optical parametric amplification is analyzed and calculated in detail.It involve the phase-matching condition,the walk-off in spatial and in temporal.The basal scheme of high repetition optical parametric amplification is summarized.These conclusions provide significant reference for the the investigation of ultra-broadband optical parametric amplification.2.A novel ultra-broad bandwidth optical parametric amplification approach is investigated in this dissertation for the pump pulse with broadband.It is the scheme of based on pre-chirp controlling.The phase-matching condition is satisfied in a ultra-broadband signal spectral range.The per-chirp controlling provides temporal overlap of phase-matched spectral components between the signal and the pmp.The photonic crystal fiber with a zero-dispersion wavelength at degeneracy generates a supercontinuum with a quadratic chirp.The broadband pump pulse is stretched to a linear chirped pulse.They meet the desired spectrum of signal and pump.The theoretical analysis and calculations are also performed.The innovation in this dissertation is the comprehensive investigation in theoretics and experimentation to this scheme.3.The generation and the pre-chirp controlling of signal and pump is investigated in theoretics and experimentation.The signal is the supercontiuum which is generated by the photonic crystal fiber.The mechanism of the supercontinuum generation is analyzed theoretically.The dispersion of supercontinuum in the photonic crystal fiber is investigated as well.It is the concernful precondition of the pre-chirp controlling. The supercontinuum with a broad bandwidth from 470nm to1010nm was generated with the femotsecond Ti:sapphire system in experiment.The pump is the second harmonic of amplified Ti:sapphire system.The basal theoretics of frequency doubling is analyzed and the broadband frequency doubling scheme based on angular dispersion is investigated.A second harmonic generation with 2mm BBO was researched with Ti:sapphire chirped pulse amplification syetem.The bandwith with 7nm of the second harmonic was obtained.The conversion efficiency can reach 20%. The theoretical calculations are performed to the chirp controlling of the pump.These provide specific reference for pre-chirp controlling.4.Experimental investigations of optical parametric amplification have been carried out with the KHz Ti:sapphire femtosecond laser amplification syetem.First the tunable collinear optical parametric amplification was investigated in experiment. The signal was supercontinuum that was generated from a photonic crystal fiber.The amplified spetra tunable range from 500nm to 800nm and the idle laser range from 800nm to 2000nm was obtained.Secondary,the ultra-broad bandwidth optical parametric amplification based on pre-chirp controlling was investigated in experiment. The broadband pump pulse is stretched to a linear chirped pulse by a prism pairs according to the dispersion of supercontinuum.The phase-matched spectral component keeps synchronization by controlling pre-chirp.The gain bandwidth of up to 200nm was obtained.The conversion efficiency was approach 8%and the pulse energy was 3μJ.