We present an experimental setup to generate partially coherent Ince-Gaussian beams. The partially coherent field is constructed using a rotating ground glass disk to reduce the spatial coherence of a laser source and digital holograms. Our results show that the cross correlation function of these beams inherit properties of their spatial structure. The experimental cross correlation function is measured by means of a well known wavefront folding interferometer, which allows us to characterize the properties of the beam. The comparison between theoretical and experimental results yields excellent agreement.
We study the spatial coherence properties of partially coherent vortex beams. The mathematical model employed for the generation and control of the spatially partially coherent beam is based on a statistical model, in which the field is constructed from the incoherent superposition of an ensemble of individual vortices carrying topological charges of different values and handedness. Results show that if the ensemble from which the partially coherent vortex is generated consists of a mixed composition of individual vortices it is not always possible to determine its topological charge unambiguously.
A means to digitally generate a partially coherent beam with orbital angular momentum is presented. Our approach is based on encoding the randomness of broadband light passing through a spiral phase plate in a spatial light modulator. We illustrate the technique by generating partially coherent beams with orbital angular momentum content and different coherence lengths, with no moving optical elements. We study the cross correlation spectra which yields to good agreement with theory.
An alternative method to experimentally measure the topological charge of a vortex beam is presented. The method is based on the number of polarization singularities arising in the superposition of two off-axis Laguerre-Gauss beams having orthogonal polarizations. The experimental setup consists of a modified Mach-Zehnder interferometer which provides control over the polarization structure by allowing us to introduce lateral displace ments as well as relative phase variations between the two arms of the interferometer. A comparison between theoretical and experimental results is done with very good agreement. This method offers an alternative for measuring orbital angular momentum content in a beam without the need of interfering with a reference plane wave. The dynamics of polarization singularities are also studied experimentally.
A means to measure orbital angular momentum in a partially coherent beam is demonstrated by using a wavefront
folding interferometer. This interferometer allows us to study the cross correlation function of a partially coherent
vortex beam. It is shown that the cross correlation function possesses ring dislocations which are related to the
topological charge of the partially coherent vortex, exhibiting a one to one correspondence between the number of
rings and the value of the topological charge, thus providing a direct measure of the orbital angular momentum.