RESUMEN
We investigate the transfer of orbital angular momentum (OAM) in a type-II optical parametric oscillator (OPO). We produce different kinds of transverse modes on the downconverted beams by pumping the OPO with a first-order Laguerre-Gaussian beam well above threshold. Different operation regimes are attained showing a rich variety of transverse modes bearing OAM.
RESUMEN
We investigate the topological phase associated with the double connectedness of the SO(3) representation in terms of maximally entangled states. An experimental demonstration is provided in the context of polarization and spatial mode transformations of a laser beam carrying orbital angular momentum. The topological phase is evidenced through interferometric measurements, and a quantitative relationship between the concurrence and the fringes visibility is derived. Both the quantum and the classical regimes were investigated.
RESUMEN
We present a study of spatial structures created by superposition of spiral zone plates used for generating optical beams with phase singularities. Moiré fringes are observed that show topological defects similar to those appearing in interference patterns of optical vortices. A brief theoretical discussion is included that supports the similarities between the two phenomena. Our results may lead to interesting applications to digital information processing by optical means.