Design of multi-channel phase spatial filter for selection of Gauss-Laguerre laser modes

We synthesize a multi-channel phase filter to decompose the light fields into the basis of generalized Gauss-Laguerre modes, Psi(nm)(r, phi), 0less than or equal ton,\m\less than or equal toN. The filter allows any of nine specified modes to be selected. The contribution of any mode to the image under analysis can be determined from the correlation peak in the focal plane of the corresponding diffraction order. The choice of an optimal radius of the plane and Gaussian illuminating beams is studied. The results on computer simulated selection of desired modes from the laser beams composed of a linear combination of Gauss-Laguerre modes are discussed.