Variable reflectivity laser mirror study based on chirped volume Bragg grating

• Main Authors: Zhao-jie Chen, 陳昭介
• Other Authors: Te -Yuan Chung
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/w6646a

碩士 === 國立中央大學 === 光電科學研究所 === 97 === The laser’s output efficiency is smaller than before when laser opperated high power because thermal lens did. The thesis disscused the laser’s output efficiency unstable because emission cross section was changed with temperature. The experiment used the Nd:YAG laser system and supposed the reflectivity was adjustable. Then simmulated four different types control system 1 CW laser、2 actively Q-switch laser、3 Amplified spontaneous emission、4 Passively Q-switched laser. This method based on variable reflectivity mirror so we suggest used the temperature difference to control VBG’s incide period and reflectivity. Thus by simulation we can get how the reflectivity changed to recover gainmedium stimulated emission thermal effection and make output energy was temperature independent. We used the difference temperature on the VBG to let the period structure becomed unperiod streucure, thus the reflectivity was decreased. Then the reflectivity was variable by controling temperature difference on VBG. How much temperature difference value that we were need. First the expansion distribution be gotten by used Comsol multiphysics when VBG was temperature difference,thus we can get unperiod structure. And then used the T-matrix to measure refletion、transition、propagation optical difference to get the reflectivity. Finally, we uesd difference temperature VBG to be output laser mirror and got the reflectivity by threshold power and slope efficiency. The result can change reflectivity by temperature difference.