Our calculations show that the Bessel-Gauss beam can be produced in the focused plane of the ring apertured Gaussian beam, this method is efficient and simple.
The results indicate that with the increase of focal length, the intensity distribution on the focal plane varies from central-dip form to Gaussian distribution.
结果表明：随着聚焦距离的增加，焦面光强分布由中央凹陷状向高斯分布转变。
3
The relations between pump absorption losses and the waveguide cavity configuration parameters are calculated based on the Gaussian beam transformation in the plane-parallel resonator.