圆形高斯镜平凹腔腔内外激光场研究

Study of the laser field distribution of circular plano-concave resonator with a Gaussian reflectivity mirror

运用边界元素法把圆形高斯镜平凹腔的自再现模的衍射积分方程转化为有限阶矩阵方程。计算了圆形高斯镜取不同反射率膜斑半径和中心振幅反射率情况下基模的场强分布、相位分布和本征值。研究表明:腔内光场分布半径随反射率膜斑半径的减小而增大,中心振幅反射率不影响光场分布半径;反射率膜斑半径影响远场分布,当其数值较小时,在光束的远场分布主峰周围产生弱衍射环;当高斯镜中心全反射时,远场分布随反射率膜斑半径的变化无明显变化;模式本征值随反射率膜斑半径的增大而增大。

By means of boundary finite-element method,the field distribution and eigenvalue of the fundamental mode of the plano-concave resonator with a Gaussian-reflectivity plane mirror are calculated and discussed.The results show that the radius of the mode increase following the decreasing of the characteristic radius of the Gaussian-reflectivity.The radius of the mode is not affected by the changes of the amplitude-reflectivity of mirror center.The characteristic radius of the Gaussian-reflectivity affect the far field distribution of the laser mode.While its value is small,the far field distribution has the diffraction ring around the main peak.In addition,if light is reflected completely at the center of the Gaussian-reflectivity plane mirror,the changes of the far field distribution is not obvious with the characteristic radius of the Gaussian-reflectivity changing.The mode eigenvalue increases with the characteristic radius of the Gaussian-reflectivity increasing.