Polarization Convertor Design And Application Features Analysis Of The Femtosecond Vector Beams

As a kind of uneven polarized lights,the vector beams possess fairly advantageous features in focusing and transforming,thus enjoying promising application prospects and having been drawing increasing numbers of researchers into the analytical investigations.With the rapid development of the modern laser technology,it has been realized nowadays that the pulse width be compressed to the level of femtosecond and attosecond by various approaches,thereafter,it has made the peak power of the pulse reach the extent of 1024W/cm2.It is paramount and significant to the direct interactions of the laser and particles.Therefore,the study to the properties of the combination of the two techniques,named femtosecond vector beams which could bring about some new characteristics,contains the two superiorities,enjoying a positive practical sense.The work of this paper contains as following1.Designing and processing the radial polarization convertors oriented to the super-high femtosecond laser.On the principle of the polarization converting,the basis of the birefringence features of Yb VO4 and the nature of the phase delay in the phenomenon of total reflection,respectively design two kinds of devices to meet the converting,and utilize the micro-nano IBE and the traditional technology and craft on optical components to manufacture the concerning structures which could meet the designing requirements;2.Exquisite model and stimulation analysis on the vector distributions of femtosecond radially polarized beam's focusing field.Based on the Richard-Wolf vectorial diffraction theory,analyze the focusing features of the few-cycle vectorial polarized beams,concentrate on the exquisite distributions of the focusing field,establish the veatorial model and conduct some model analysis,the aspects concerned include the purity,dispersion,diffraction and wavelength factors;3.Experimental measurement on the focal intensity distributions of the radially polarized beams.Synthetically analyze the relative merits of the detection approaches,then take advantages of the “Knife-Edge” method,design a precise 3D-adjustable measurement system,detect the focal electric intensity distributions,analyze the focusing features from different numerical apertures and different convertors,and realize the detection on the level of micrometer.The theory analysis shows that the RPB owns superior focusing characters,especially for its ultra-high longitudinal components after being focused,which is of great value for the practice applications and besides,the attempt to utilize Yb VO4 crystals as conversion material to obtain the RPB in the condition of high peak power isavailable Also,the “Knife Edge” detection method can make the sense to analyze the focusing spots in the level of micrometer,of course,while the precision and the error should be further controlled,and the level of the integration should also be optimized.In a nutshell,the study provides certain foundations and guidance on the theory and experiment for the following work,including the acquisition of the purer radially polarization beams with higher peak power and the trials on the laser-particle interactions.