Grupo de Tecnologías Ópticas y Optoelectrónicas

María del Mar Sánchez-López and Shang Gao attended the SPIE Photonics Europe conference held in Strasbourg, France, in 7 – 11 April 2024.

María del Mar presented an invited talk entitled Dynamic control of polarization oscillating Bessel beams through liquid-crystal anisotropic axicons.

Shang presented the poster entitled Feasibility study of liquid-crystal spatial light modulators for displaying triplicator gratings at their spatial resolution limit.

Both works were presented within the conference Liquid Crystals Optics and Photonic Devices, where María del Mar also participates as a Program Committee member.

Our last paper entitled Mueller matrix imaging polarimeter with polarization camera self-calibration applied to structured light components is published at JEOS-RP. The paper is open access and available at PDF

The work presents a complete Mueller matrix imaging polarimeter that uses three liquid-crystal retarders and a polarization camera. The polarimeter is characterized and optimized with a standard correction procedure here adapted to be performed fully in-situ, without any additional element, based on considering the polarization camera as the reference. The accuracy limit caused by the extinction ratio in the camera micro-polarizers is analyzed. Finally, the imaging polarimeter is tested experimentally by analyzing well-known samples for structured light applications such as patterned retarders, a patterned polarizer, and a liquid-crystal depolarizer. The work is presented in a tutorial style useful to reproduce the procedure by non-experts in polarimetry.

This paper is part of the PhD Thesis of Esther Nabadda, and it has been done in collaboration with our colleagues Asticio Vargas, from the Universidad de La Frontera in Chile, and Angel Lizana and Juan Campos from Universitat Autònoma de Barcelona.

Our last paper is now published in Chinese Optics Letters entitled Experimental implementation of phase triplicator gratings in a spatial light modulator.

It reports on the different methods for implementing a triplicator, a phase grating that generates three equi-intense diffraction orders. The design with optimal efficiency features a continuous phase profile, which cannot be easily reproduced, and is typically affected by quantization. We compare its performance with binary and sinusoidal phase profiles. We also analyze the effect of quantizing the phase levels. Finally, a random approach is adopted to eliminate the additional harmonic orders.

In all cases, a liquid-crystal-on-silicon spatial light modulator is employed to experimentally verify and compare the different approaches.

This work is part of the PhD thesis of Shang Gao.

Ignacio Moreno attended SPIE Photonics West held in San Francisco from January 27th to February 1st, 2024.

There he presented our work entitled Analysis of polarization diffractive patterned polarizers and retarders, within the conference Complex Light and Optical Forces XVIII.

TecnOPTO participated at the kick-off meeting of FASLIGHT, the Spanish Network on Fundamentals and Applicationc of Structured Light, held in Salamanca in January 18th-19th, 2024.

TecnOPTO is one of groups participating in the newtwork. David Marco, Pascuala Garcia, María del Mar Sánchez-López and Ignacio Moreno attended the first meeting.

We had the visit of Prof. Gladys Mínguez, from the Group of Optics (GROC) of the University Jaume I de Castellón (UJI).

She was invited within the frame of the UMH Master of Biotechnology and Bioengineering, where she delivered an excellent presentation entitled «Synthesis of nanomaterials with pulsed lasers and their bioapplications».

On May 17th 2023, Pascuala Garcia-Martinez was interviewed at «Oscilador Armónico”, the podcast broadcast about physics made at IFIC – Instituto de Física Corpuscular, a joint center of CSIC and teh University of Valencia.

The full interview is now available at the following link.

The program of that day was entitled «Óptica, Fotónica y la Física de la Luz»  and along the interview, Pascuala talked about the International Day of Light, some of the many applications that Optics and Photonics has nowadays, and about her work and research.

We had the honor to receive the visit of Prof. Miguel Alonso, Directeur Adjoint de la Recherche del Institute Fresnel, Marseille (France), Professor at the Institute of Optics, University of Rochester (USA) and Editor-in-Chief of the journal Optics Letters.

We invited Prof. Alonso to a combined visit to the Faculty of Physics of the University of Valencia (UV), where he dekivered the conference «The geometry hidden in Optics» and to the Institute of Bioengineering at UMH.

David Marco, who is now finishing a two-year postdoctoral stay at Marseille to work with Prof. Alonso, also joined in the visit. This reunion was held within the frame of a joint project (CIAICO/2021/276) of Generalitat Valenciana, also with the participation of Pascuala Garcia-Martínez and Eugenio Roldán from UV.

The picture shows us, from left to right Shang Gao, Esther Nabadda, David Marco, Miguel Alonso, María del Mar Sánchez-López and Ignacio Moreno.

A new paper is now published in Optical Engineering entitled Multiplexing onto a spatial light modulator using random binary patterns. In this paper we analyze the random approach for encoding a variety of independent outputs from a multiplexed computer-generated diffractive element displayed on a SLM. Although the technique was demonstrated years ago, nowadays it can be applied with high-resolution SLMs with a very large number of pixels, thus allowing for a larger number of multiplexed functions without significant degradation. Nevertheless, we show that the technique is quite sensitive to the pixel crosstalk caused by the fringing field of modern LCOS SLMS, leading to a significant undesired DC order. Two alternative strategies to avoid this degradation.

The work has been done in collaborators Jeffrey A. Davis and Don M. Cottrell from San Diego State University (USA). It is the first paper published by PhD student Shang Gao.

Our new paper entitled Liquid crystal anisotropic axicon for the generation of non-diffracting Bessel beams with longitudinally varying polarization is now publised in the journal Optics and Laser Technology.

In this work we demonstrate a tunable liquid–crystal element of linear phase profile along the radial coordinate. In combination with a regular refractive axicon, it behaves as an anisotropic axicon, generating the collinear superposition of two orthogonally polarized Bessel beams with different propagation constant. This superposition results in a Bessel beam where the state of polarization (SOP) varies periodically along propagation.

The work has been done with our collaborators at the Military University of Technology, Warsaw (Poland), Noureddine Bennis, Anna Spadlo and Tomasz Jankowski, together with José Francisco Algorri, from University of Cantabria, in Santander (Spain).