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Study On Thermal Effects Of The Crystal In Diode Solid-state Lasers

Posted on:2011-12-26Degree:MasterType:Thesis
Country:ChinaCandidate:L C GuoFull Text:PDF
GTID:2178360302491545Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Thermal effect plays a very important part in solid state lasers, based on the diode pumped solid state lasers, the thermal lens effect was theoretically analyzed and numerically simulated, and also was the dispersion effect. The creative point of the paper is that the distribution of the temperature inside the laser crystal and the thermal focal length with Gauss pump source in 4-order approximation were deduced.Based on the four level laser rate equation, the paper discussed the effect of Gauss beam on the fundamental mode Gaussian oscillating light, the Overlap integral of pump beam and low level Gauss oscillating light were calculated, and the effect of the matching degree between pump beam and oscillating light on the output characteristic was also analyzed.Secondly, the thermal focal length of the laser crystal caused by temperature gradient was primary studied. The research approach was as follows:1. The light distribution of Gauss and super Gauss pump beam was discussed;2. With different pump source, the three-dimensional temperature field in the laser crystal was simulated on condition that the temperature on the crystal side remained constant. The expression of the temperature in the laser crystal with Gauss pump source was analytically deduced in 4-order approximation, and the temperature distribution in the crystal with super Gauss source was numerically simulated;3. The thermal focal length of the laser crystal was theoretical deduced;In order to describe the thermal lens visually and clearly, The ANSYS and MATLAB were used. The phase distortion of the plane wave through the crystal was numerically calculated, the variation of the thermal focal length with radius was studied. The study showed that the thermal lens was non-ideal under normal conditions. The plane wave would become non-spherical when it transmitted through the crystal and form a dispersion spot in the space.A mathematical parameter named M was put forward to describe this dispersion effect of the thermal lens. M was defined as the ratio of the radius of minimum dispersion spot to that of diffraction limit light spot. The study found that the distance between the minimum light spot and the back face of the crystal decreased when the pump power increased, and increased when the pump beam radius increased. The minimum radius of the dispersion spot was not irrelevant to the pump power but pump light radius. The parameter M increased when the pump power increased, and decreased when the pump beam radius increased. It came to the conclusion that the quality of the light spot would get better with lower pump power and bigger pump beam radius.
Keywords/Search Tags:Diode pump solid state lasers, Thermal effect, Thermal lens focal length, Numerical simulation, Dispersion effect
PDF Full Text Request
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