Analytical solutions for the electromagnetic fields of flattened and annular Gaussian laser modes I Small F-number laser focusing

Scott M. Sepke, Donald P. Umstadter
2006 Journal of the Optical Society of America. B, Optical physics  
Many laser interaction models assume that incident focused laser fields are Gaussian and use either the approximate TEM 00 series model or the exact integral Gaussian angular-spectrum solution. Many practical laser systems, however, produce flat-top transverse intensity profiles, and indeed, such profiles are often desired. Here, an exact, integral solution is derived for all of the vector components having a general flattened Gaussian profile using the angular-spectrum method. This solution
more » ... ludes the pure and annular Gaussian modes as special cases. The resulting integrals are solved for tight focusing conditions exactly by making use of a Fourier-Gegenbauer expansion. This technique follows closely that of Umstadter [Opt. Lett. 31, 1447 (2006)] but, by redefining the expansion coefficients, the simplicity of the model is greatly enhanced and the computation time reduced by roughly a factor of 2 beyond the 2 orders of magnitude improvement obtained previously. This series solution is stable at all points and converges after S ϳ 20w 0 terms, where w 0 is the 1 / e waist normalized to the laser wavelength.
doi:10.1364/josab.23.002157 fatcat:ylb3i7ysz5d7rhlmr7tzpq3grq