There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Wave propagation and group velocity

Emerging applications based on optical beams carrying orbital angular momentum (OAM) will probably require photonic integrated devices and circuits for miniaturization, improved performance, and enhanced functionality. We demonstrate silicon-integrated optical vortex emitters, using angular gratings to extract light confined in whispering gallery modes with high OAM into free-space beams with well-controlled amounts of OAM. The smallest device has a radius of 3.9 micrometers. Experimental characterization confirms the theoretical prediction that the emitted beams carry exactly defined and adjustable OAM. Fabrication of integrated arrays and demonstration of simultaneous emission of multiple identical optical vortices provide the potential for large-scale integration of optical vortex emitters on complementary metal-oxide–semiconductor compatible silicon chips for wide-ranging applications.

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Integrated Compact Optical Vortex Beam Emitters

Space-variant Pancharatnam-Berry phase optical elements based on computer-generated subwavelength gratings are presented. By continuously controlling the local orientation and period of the grating we can achieve any desired phase element. We present a theoretical analysis and experimentally demonstrate a Pancharatnam-Berry phase-based diffraction grating for laser radiation at a wavelength of 10.6microm.

Space-variant Pancharatnam-Berry phase optical elements with computer-generated subwavelength gratings.

Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized.

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Roadmap on structured light

We present a holographic projection system based on the encoding of computer-generated holograms onto a spatial light modulator. We show how the size, location, and polarization state of the output can be controlled electronically, without physically moving any element. Experimental results are included in all cases

SLM based holographic projection system without moving elements

A new polarization state generator (PSG) is presented based on two geometric-phase diffraction gratings, useful to generate partially polarized light in an efficient and controlled way. The PSG is used to experimentally analyze the generation of vector and vortex beams which lie, respectively, inside the generalized higher-order (HOPS) and the orbital angular momentum (OAMPS) Poincaré spheres. This way the mapping relations between polarization states, vector beams and vortex beams are analyzed and the classical concept of degree of polarization (DoP) is extended to these other Poincaré spheres. Experimental results that validate the theory are presented.

Polarization state generator for the generation of complex light with controllable degree of polarization

A technique to derive the spatial deformation of a liquid-crystal on silicon spatial light modulator based on a self-interference effect, generated when it is illuminated with a wavelength far from the operation range, is presented.

Measuring the non-uniformity of a liquid-crystal on silicon spatial light modulator with light out of the operation range

Optics and photonics innovative education networking: synergies between universities around learning

The link between depolarization measures and physical nature and structure of material media inducing depolarization is nowadays an open question. This article shows how the joint use of two complementary sets of depolarizing metrics, namely the Indices of polarimetric purity and the Components of purity, are sufficient to completely describe the integral depolarizing properties of a sample. Based on a collection of illustrative and representative polarimetric configurations, a clear and meaningful physical interpretation of such metrics is provided, thus extending the current tools and comprehension for the study and analysis of the depolarizing properties of material media. This study could be of interest to those users dealing with depolarization or depolarizing samples.

Ignacio Moreno

Papers

SLM based holographic projection system without moving elements

Polarization state generator for the generation of complex light with controllable degree of polarization

Measuring the non-uniformity of a liquid-crystal on silicon spatial light modulator with light out of the operation range

Optics and photonics innovative education networking: synergies between universities around learning

Unraveling the physical information of depolarizers