Study On The Propagation Properties Of Laser Beams By A Left-handed Material Slab

The Left-handed material(LHM) is also called negative refractive index media,which is put forwarded from theoretically by Soviet scientist Veselago in1968. As a newtype of synthetic electromagnetic material, which has many peculiar physical opticalproperties because of it’s negative refractive index, such as inverse Doppler effect,negative refraction effect, inverse Cherenkov radiation, etc. Thus, it has importantsignificance to study on the propagation properties of laser beams by a Left-handedmaterial slab.In this paper, we mainly study the propagation of laser beams in the Left-handedmaterials and laser beam through the Left-handed materials slab. The main works are asfollows:Firstly, briefly reviews of the development history in the transmission andtransformation of the laser beams, also detailedly introduces the laser beams involved inthis paper and theoretical system of it by a Left-handed material slab.Secondly, we study the propagation properties of the cosine-Gaussian beam by aLeft-handed materials slab. Under the paraxial approximation, using generalizedHuygens-Fresnel diffraction integral to deduce the propagation expressions ofcosine-Gaussian beam through the Left-handed material slab. By using numericalcalculation, the negative refraction index of left-handed materials slab and the influence ofpropagation properties due to the modulation parameter of cosine-Gaussian beam isstudied. The results of the study show that, whether in the left-handed materials slab orimage space, the location of the axial maximum light intensity is the position ofcosine-Gaussian beam which is focused, and the negative refractive index of theLeft-handed material slab can change the position of the cosine-Gaussian beam focusing.In the internal of the Left-handed material slab, the negative refractive index can change the shape of the axial light intensity distribution, but not change the shape of Spatialintensity distribution on space axial. Whether in slab internal or image space, the axial andtransverse light intensity can be influenced by the modulation parameters ofcosine-Gaussian beam.Finally, we study the propagation properties of the flattened Gaussian beams by aLeft-handed material. By using the Collins formula under the paraxial approximation, thepropagation of the flattened Gaussian beams by a inner Left-handed material and the fielddistribution expressions through a Left-handed material are analyzed. The results of thestudy show that, the negative index can change the distribution of the axial light intensitybut the shape in the space, moreover, light intensity has a maximum value in the focusposition of light beam. Whether in the internal media or image space, the beam order isalways could change shape of light intensity distribution. The shape of the intensitydistribution on the axis that symmetrical about the focal spot, the shape of the transverseintensity distribution is symmetrical about the light axis. Transverse intensity distributionpresents minimum value in the internal media while the maximum value is presented inthe image space.