Grupo de Tecnologías Ópticas y Optoelectrónicas

We published a new paper in Optics & Lasers in Engineering entitled Geometrical-phase lens based optical system for the spin-splitting of vector beams. 

In this work we combine a geometric phase lens and a telescope system to produce an optical system with two polarization controlled real foci with equal magnification. And we apply it to characterize vortex beams and vector beams, splitting longitudinally the circular polarization components and focusing them into different axial planes.

This work was develop din collaboration with our friends Asticio Vargas and Fabián Torres-Ruiz, from Universidad de La Frontera, Temuco (Chile). And it is part of the PhD Thesis of Aarón Cofré.

On July 10th 2018, Aarón Cofré presented the defense of his PhD Thesis entitled Development of advanced diffractive systems for the generation of optical vortices and structured polarized beams.

The Thesis has been supervised by Ignacio Moreno and Asticio Vargas, and included various experimental studies on how to generate optical vortices and vector beams.

The results of the thesis resulted in four articles published in the journals European Journal of Physics, Optics & Lasers Technology, Optics Express and Optics & Lasers in Engineering respectively.

In the picture, Aarón with the supervisors and the members of the jury.

We published a new paper in Optics Letters entitled Achromatic linear retarder with tunable retardance.

In this work we present a universal design and proof-of-concept of a tunable linear retarder of uniform wavelength response in a broad spectral range. It consists of two half-wave retarders (HWR) between two quarter-wave retarders (QWRs), where the uniform retardance can be tuned continuously by simply rotating one of the HWRs. A proof-of-concept of this design is built by using commercially available Fresnel rhomb retarders that provide retardation with almost wavelength uniformity in the visible and near infrared from 450 to 1550 nm. The system is experimentally demonstrated to control the state of polarization of a super-continuum laser.

The work has been developed in collaboration with Asticio Vargas, from Universidad de la Frontera, Chile. And it is part of the PhD thesis of Abdelghafour Messaadi.

A new paper has been published entitled Programmable zoom lens system with two spatial light modulators: Limits imposed by the spatial resolution, published in the journal Applied Sciences, in a special issue devoted to liquid crystal on silicon devices.

This paper deals with the realization go a zoom lens system that used two liquid-crystal SLMs, so different magnifications can be obtained without any moving elements, simply by changing the focal length of the lenses displayed in each SLM. We include results with positive and negative magnifications. And we analyze the limits imposed by the limited spatial resolution of the SLMs.

The work has been developed at the Department of Physics at San Diego State University, with the participation of Ignacio Moreno.

The conference How Photonics lights the world delivered by Prof. Boreman at University Miguel Hernández on May 21st, 2018 is now available at the following link. This is part of the International Day of Light celebration.

A new paper in the journal Optics & Laser Technology entitled Spectral performance of a zero-order liquid-crystal polymer commercial q-plate for the generation of vector beams at different wavelengths.

It deals with the use of liquid-crystal polymer q-plates operated at different wavelengths. We show how a broadband spectral characterization allows identifying the wavelengths with retardance values relevant for vector beam generation (π, π/2, and 3π/2). The wavelength is then used as a tuning parameter to change the device performance from the standard half-wave q-plate to a positive or a negative quarter-wave q-plate.

We present a simple procedure to derive the polarization distribution of the generated vector beams, and show that they can produce hybrid vector beams when operated at non-design wavelenths. Therefore, these results could extend the use of commercial q-plates for multicolour vector beam applications.

This work has been done in collaboration with Prof. Jeffrey A. Davis and Isaiah Abella, from San Diego State University.

Ignacio Moreno participated as invited speaker in the Workshop on Adaptive Optics for Industry and Medicine AOIM XI, organized by Pablo Artal and his group at the University of Murcia, in March 2018, 4-7.

Our latest results on the adaptive generation and detection of vector beams by means of liquid crystal spatial light modulators were presented in the talk entitled “Polarization Diffractive Elements displayed in Liquid Crystal Spatial Light Modulators”.

The workshop had very interesting talks, and a great ambience.

We published a new paper in Applied Optics entitled Q-plates with a nonlinear azimuthal distribution of the principal axis: application to encoding binary data. This work has been developed with out colleagues at San Diego State University.

Here we use the optical system developed at SDSU to control two linear polarization components to encode q-plates where the angular orientation of the principal axis is varied spatially with a nonstandard distribution. We consider two cases: first, where the principal axis distribution is like an inverse-tangent function of the azimuth; and second, where it displays linear and flat segments. This last case is proposed as a new method for encoding binary data into the azimuthal lobes of the vector beam.

The use of the spatial light modulator based system allows these new and exotic q-plate designs without the difficulty of fabricating individual plates. Experimental results are presented.

Ignacio Moreno attended Photonics West, in San Francisco, in February 2018, 2nd-7th. An invited talk was presented by Jeffrey A. Davis on our mutual collaboration entitled Polarization state vector beam spectrum analyzer using q-plates encoded onto a spatial light modulator at the SPIE OPTO conference  Complex Light and Optical Forces XII, chaired by Enrique J. Galvez, David L. Andrews, and Jesper Glückstad. A related manuscript is available at the SPIE Proceedings Volume 10549, Complex Light and Optical Forces XII; 105490L (2018). Link

Ignacio Moreno, as the current President of the Spanish Society of Optics – SEDOPTICA, signed the renovation of the collaboration agreement with SPIE. The picture shows Dr. Maryellen Giger, 2018 SPIE President, signing the agreement with Ignacio.

Our friends Asticio Vargas and Fabián Torres, from Universidad de La Frontera (UFRO) in Temuco, Chile, visited TecnOPTO-UMH lab in January 2018.

For two weeks we have been able to work together and continue our fruitful collaboration and develop common research projects. The Spanish-Chilean connection continues.