Research On The Transmission Characteristics Of A New Type Of Laser Beam In A Gradient Index Medium

With the development of laser technology,laser optics have gradually evolved into an independent subject,attracting the attentions of researchers.And due to the wide applications in device fabrication and material preparation,gradient index optics combined with laser optics are becoming a research hotpots.The paper mainly studies the propagation properties of two kinds of new optics beams,hollow sinh Gaussian beams and four-petal Gaussian vortex beams in the gradient index medium.Firstly,the research background and development history of laser optics and gradient refractive index are briefly reviewed.And we introduce the research progresses at home and abroad.The basic theory,research methods,mathematical and physics model of gradient refractive index media are introduced.Secondly,by combining ABCD transmission matrix with the Collins integral formula,the analytical expressions of hollow sinh Gaussian beam in gradient index index media are derived.The propagation properties of hollow sinh Gaussian beam in gradient refractive index media are numerical simulated by using the MATLAB software.Results show that the intensities of the hollow sinh Gaussian beam appear periodic evolution on its axis.On the source plane,the beam takes on the dark hollow stricture and Gaussian distribution with the petals at the half of the period.At length,the beam turns back into the dark hollow stricture which is exactly the same as the intensity distributions at source plane.As for the beam order n,the higher beam order n,the stronger ability of the hollow sinh Gaussian beam maintaining its dark hollow ring structure on the source plane.In addition,An intensity peak exists at the center of two in phase beams,which is equal to zero for two out of phase beams.At last,we investigate the propagation proprieties of the four-petal Gaussian vortex beam in the gradient index medium.Analogously,the analytical expression of the four-petal Gaussian vortex beam in gradient index medium is discussed.The numerical simulation results show that intensity distributions and phase distributions of four-petal Gaussian vortex beams are influenced by combined effects of beam parameters.For a propagating period,they are of four petals structures near the source plane.And at length,they will evolve into the four petals structure.At the half of the period,a hollow optical wall structure or a central principal maximum surrounded by symmetrical side lobes will occur,which is determined by the parity of the topological charge number m.There are potential values of the researches and understandings of the hollow beams and vortex beams with gradient index optics.In addition,there are also potential values of the practical applications for beam shaping and beam regulation in the future.