The Research On Propagation Properties Of Lorentz-Gauss Beam

Semiconductor is laser diode’s working substance. Because of this difference, The semiconductor laser light by semiconductor laser, such as double heterojunction Ga1-xAlxAs semiconductor laser, is cannot use simple ordinary laser beams to describe. O.E.Gawhary and S.Severini proposed a new beam which is suited to describe this beams of the semiconductor laser light in2006, i.e. Lorentz-Gauss beam. After the propasal of new beam, many practical value such as particle capture, laser material processing and beam shaping and so on become possible to realize. This master thesis which involves the study of propagation properties of Lorentz-Gauss beam is written to carry on the theoretical analysis.In this thesis, the focusing property of Lorentz-Gauss beam through ideal lens is studied. I use the Collins formula to get the output optical field’s integral formula. Then with the help of Fourier transform, convolution formula, special integral result and aperture which is expanded as the superposition of complex gaussian function, we get the light field analytical solution. After that, we use the method of Li-Wolf and the definition of focal shift and focal switch to judge the phenomenon. Firstly the focal shift can be produced through ordinary optical system. The influencing factors which decide the location of the the actual focal point which is located at the geometrical focal point to the right or left are obtained. Then using the same reasearch to analyze the factors to realize focal switch by phase aperture which are the size of phase aperture and periodic change of phase factor.The focusing property of Lorentz-Gauss beam through astigmatic lens is studied. Use the theory of the same method to get another method to realize focal switch. Then I arrive the transmission properties of Lorentz-Gauss beam which get through the astigmatic lens. Respectively we analysis two aspects, the ideal situlation which consider the size of lens and actually consider the lens size, and get the influencing factors of focal shift and focal switch. According to the results, whether can realize the capture of nanoparticles which is in the range of the Rayleigh scattering in the location which renlize focal switch is analyzed.The focusing property of Lorentz-Gauss beam through fractional Fourier optical system is studied. Afterwards through the analysis of with different aperture (rectangular, circular, phase aperture) and using the Collins formula, we can get the integral expression on the surface of fractional Fourier. Then we can obtain the analytical solutions through integration. At last, we can receive the flattened uniform beam, hollow beam and its creation conditions. We can also obtain the beam which changes the brightness periodically through adjusting parameters.