Prof. Pascuala García-Martínez has become a new 2021 SPIE Fellow member for her achievements in optical systems for image processing, diffractive optics and polarization, and for her activity on the promotion of women in science.
Access to her SPIE profile: Pascuala García-Martínez (spie.org)
A new paper is available in the journal Crystals entitled Mueller matrix polarimetric imaging analysis of optical components for the generation of cylindrical vector beams, in a special issue of the journal devoted to Liquid Crystals Optical Devices.
In this work we perform a Mueller matrix imaging analysis of two commercial optical components usually employed to generate and manipulate vector beams—a radial polarizer and a liquid-crystal q-plate. These two elements generate vector beams by different polarization mechanisms—polarizance and retardance, respectively.
The quality of the vector beams relies on the quality of the device that generates them. For this purpose, we applied a customized imaging Mueller matrix polarimeter based on liquid-crystal retarders and a polarization camera. Experimental results were compared to the numerical simulations, considering the theoretical Mueller matrix.
This work was done in collaboration with our colleagues Angel Lizana and Juan Campos from the MIP-Optilab at Universitat Autònoma de Barcelona, in the frame of our coordinated national project.
Ignacio Moreno participated at SPIE Optics & Photonics conference – Digital Forum with two communications presented online. In the links below you can access the corresponding paper and presentation.
I. Moreno, M. J. Yzuel, M. L. Calvo, “The International Day of Light in Spain – a three years perspective”, Proc. SPIE 11480, Optics Education and Outreach VI, 114800H (7 pp) (2020). LINK
I. Moreno, M. M. Sánchez-López P. García-Martínez, D. Marco, A. Vargas, G. López-Morales, J. C. Quiceno-Moreno, J. L. Martínez-Fuentes, “Efficient generation of vector beams”, invited talk, Proc. SPIE 11486, Laser Beam Shaping XX, 1148602 (9 pp) (2020). LINK
Our recent paper in the Journal of the Optical Society of America (JOSA A) is entitled In-phase sub-Nyquist lenslet arrays encoded onto spatial light modulators. Here we analyze diffractive lenses encoded onto SLMs when they surpass the Nyquist limit.
This limit happens when a focal length is encoded shorter than a given distance fixed by the spatial resolution of the the display. When this limit is surpassed, a two-dimensional array of lenslets is formed. We show that, for certain values of the focal length, the lenslets are all in perfect phase. We find other distances in between where the array is composed of two sets of lenslets in phase opposition. Finally, we illustrate these phase distributions in the application to generate an array of vortex producing lenses.
This work has been done with our colleagues Prof. Don. M. Cottrell, Prof. Jeffrey A. Davis and Benjamin Gutierrez, from the Department of Physics at San Diego State University.
A new paper is available in Optics Letters entitled Measuring the spatial deformation of a liquid-crystal on silicon display with a self-interference effect.
Here we present a simple technique to characterize the spatial non-uniformity of a LCOS-SLM, based on illuminating the display with a wavelength out of the operation range. In this situation there is a significant reflection at the output surface and a Gires–Tournois type interferometer is directly created, without any alignment requirement and insensitive to vibrations. The beam reflected at the output surface is the reference beam, while the beam reflected at the silicon backplane is modulated with the addressed gray level in order to quantitatively derive its deformation. We provide an experimental demonstration using a LCOS-SLM designed to operate in the near-infrared range but illuminated with visible light.
This work is part of the PhD Thesis of David Marco and has been done in collaboration with our colleague Prof. Asticio Vargas, from Universidad de La Frontera, Temuco, Chile.
FYLA is a young Spanish laser company. At TecnOPTO we have two of their supercontinuum lasers.
We use them in a variety of experiments that include the broadband characterization of optical retarders and iquid-crystal SLMs, and their use diffractive and optical information systems.
At the following link you can access the recent interview they made to Ignacio Moreno.
We thank Gaia Sardiello for her interview and collaboration.
A new paper is available at OSA Continuum entitled Double-ring interference of binary diffractive axicons.
Here we report on the interference between the double rings generated by the Fourier transform of a binary diffractive axicon. These two rings have the same size and correspond to the +1 and -1 diffracted order beams. The interference condition between both rings can be easily changed by adding a constant phase bias. Additionally, this interference condition can be changed along the ring.
This work has been done in collaboration with our colleagues at San Diego State University Prof. Jeffrey A. Davis, Prof. Don M. Cottrell and Benjamin Gutierrez.
We are looking for a MSc, preferably with experience in experimental optics and photonics, to develop a PhD Thesis in the field of optical polarimetry within a grant from the Valencian Government, Santiago Grisolía Program, ref. GRISOLIAP/2020/004.
Required conditions
– The candidate must hold a MSc degree in Physics, Electrical Engineering, Optics or related degree from a non-Spanish institution.
– The degree must have finished after January 1st 2016 and must qualify to enter a PhD program.
– Candidates must not hold a previous PhD degree (the selected candidate will have to enroll a UMH Doctorate Program when starting the contract.
– English language OR Spanish (Spanish language is NOT required).
Recommended experience:
– Work experience in experimental and instrumental optics.
– Computational skills (Matlab, C++ , Labview…)
– Fluent English written and spoken.
Job conditions:
– Period: Three years (renewable every year)
– Starting date: October 1st 2020
– Annual gross salary of 22,192.80 euros, plus 1,600 euros to cover travel expenses.
– Social security and institutional benefits included.
Interested candidates should submit their application by email before June 23, 2020, including a CV, the contact of two persons who can provide a recommendation letter, and one motivation letter stating the candidate’s interest in the project. Contact:
Our new paper is available in Applied Sciences, entitled Analysis of hybrid vector beams generated with a detuned q-plate. This article belongs to the journal special issue devoted to Ultrafast Vortex Pulses.
We use a tunable commercial liquid-crystal q-plate tuned to a quarter-wave retardance to study the generation and dynamics of different types of hybrid vector beams. Standard hybrid vector beams but also petal-like hybrid vector beams are generated. These beams are analyzed in the near field and compared with the far field distribution, where their hybrid nature is observed as a transformation of the intensity and polarization patterns.
The work has been developed during the stay in Elche last year of Julio César Quiceno, from Universidad del Valle, in Cali, Colombia.
Our new publication is available in OSA Continuum Dynamic control of Bessel beams through high-phase diffractive axicon.
We present the realization of a high-phase diffractive axicon using a an SLM that exhibits 10π phase modulation. We compare the results with standard diffractive axicons with only 2π phase modulation. We show that high-phase modulation axicons generate Bessel beams with a shorter range and a smaller radius than standard axicons with the same period. We also find that the higher phase modulation regime provides improved diffraction efficiency since fringing effects are reduced. Dynamic control of Bessel beams is presented, controlled through the phase modulation dynamic range.
The paper has been done in collaboration with our friends at San Diego State University.