Focusing Property Of The Broadband Hermite Gaussian Beam

The propagation properties of laser beam have always been one of the main problems in the development of large-scale laser system.It is also the main problem of traffic information engineering,control and optical fiber communication.The new problems of laser physics and laser propagation are the popular contents all over the world.They are also the key issues involved in the further development of laser inertial confinement fusion and laser technology in the national high-tech development plan?In previous studies on the focused properties of laser beams,the effects of optical parameters in monochromatic light on the focused properties of laser beams are often discussed.In this paper,the influence of bandwidth of broadband Hermite-Gaussian beams on the focused properties of laser beams after passing through the optical system is mainly studied.The main research content is the following three parts:(1)Based on diffraction theory,the propagation formula of wide band laser transmission through optical appendiceal dispersion lens system in Hermitian Gao Si mode is derived.The calculation software based on mathematica is compiled and studied by numerical simulation,The focal shift phenomenon caused by the bandwidth of the TEM11 mode and the TEM22 mode Hermite Gaussian beam,The results show that with the.increase of bandwidth,The absolute value of focal shift of the TEM11 mode and the TEM22 mode Hermitian Gaussian beam also increases and shows negative focal shift.(2)The calculation and analysis are carried out.The focal switching phenomenon of the TEM22 mode wide band Hermitian Gao Si beam propagating in optical appendix dispersion lens system is studied.it is found that there are two competing maximum points of light intensity on the axis.The fast transition occurs by increasing the bandwidth to the maximum point of time,resulting in focal switching effect.(3)The influence of the physical parameters such as the number of Fresnel,the Truncation parameter and the central frequency on the focusing characteristics of the broadband-Hermite Gaussian beam is discussed.The results show that the increase of the number of Fresnel and the Truncation parameter can increase the amount of coke transfer and reduce the bandwidth required to generate the focal switch.At the same time,in some cases,the appropriate center wavelength can be selected to eliminate the focal shift phenomenon after the light beam has been focused.