Separation of Different Orbital Angular Momentum Photon States with Log-pol Transformation

An optical vortex undergoing a logarithmic – polar transformation is unwrapped from a ring – like shape to a straight line segment whose tilt is determined by the order of the vortex. Due to this property, components with continuous optical surface performing logarithmic – polar transformation are employed for the optical vortices sorting as a function of their orders. In this work we show that a logarithmic – polar component with its optical surface approximated by four discrete levels performs with a good approximation the same transformation of the optical vortices.