Helical apodizers for tunable hyper Gaussian masks

Abstract

We discuss an optical method for controlling the half-width of Gaussian like transmittance windows, by using a pair of absorption masks that have both radial and helical amplitude variations. For describing the radial part of the proposed masks, we employ amplitude transmittance profiles of the form T(ρ) = exp(-ρ s ). For s = 2, one has an amplitude transmittance that is proportional to a Gaussian function. A sub Gaussian mask is defined by a value of s < 2. And if s > 2, one has super Gaussian masks. Our discussion considers that any of these radially varying masks has also helical modulations. We show that by using a suitable pair of this type of masks, one can control the halfwidth of Gaussian like windows.