ROTATING OPTICAL-FIELDS - EXPERIMENTAL DEMONSTRATION WITH DIFFRACTIVEOPTICS

Transversally sharply structured optical fields are discussed, which r otate upon propagation without any lateral expansion of the intensity profile. Finite-aperture approximations of such fields, realizable wit h phase-only and complex-amplitude recording, are demonstrated. Record ing of at least some of the amplitude information (rather than neglect ing it completely) is shown to improve the field quality considerably, in particular close to the element. Lohmann-coded binary-phase diffra ctive elements with restricted amplitude recording are fabricated by e lectron beam lithography and reactive ion etching. The experimental re sults are in good agreement with theory.