Generating superpositions of higher–order Bessel beams

We report the first experimental generation of the superposition of higher-order Bessel beams, by means of a spatial light modulator (SLM) and a ring slit aperture. We present illuminating a ring slit aperture with light which has an azimuthal phase dependence, such that the field produced is a superposition of two or more higher-order Bessel beams. The experimentally produced fields are in good agreement with those calculated theoretically. The significance of these fields is that even though one is able to generate fields which carry zero orbital angular momentum, a rotation in the field's intensity profile as it propagates is observed.