Our last work is published in the journal Optics & Lasers in Engineering, entitled Multiple-order correlations and convolutions using a spatial light modulator with extended phase range. Here we present a new type of optical convolver / optical correlator capable of encoding multiple such operations. The technique is based on obtaining higher powers of a properly designed hologram. This can be obtained in two ways. First, we can recalculate higher powers of the amplitude and phase hologram in a standard spatial light modulator (SLM). Alternatively, we can utilize a phase-only hologram and exploit the properties of an SLM with extended phase modulation range.
The work has been done in collaboration with our colleagues Prof. Jeffrey A. Davis and Prof. Don M. Cottrell, and with Benjamin Gutierrez, from San Diego State University.
A new paper is available at the journal Frontiers in Physics entitled Programmable supercontinuum laser spectrum generator based on a liquid-crystal on silicon spatial light modulator.
In this work we present an optical system to spectrally filter a supercontinuum (SC) laser using liquid-crystal on silicon SLMs. The proposed optical system disperses the input laser and the spectrally separated components are projected onto the LCoS-SLM, where the state of polarization of each wavelength is separately modulated. Finally, recombining the modulated spectral components results in an output laser source where the spectrum can be controlled dynamically from a computer. The system incorporates two branches to independently control the visible (VIS) and the near infrared (NIR) spectral content, thus providing a SC laser source from 450 nm to 1600 nm with programmable spectrum.
We expect this new ability for controlling at will the wide spectra of the SC laser sources can be extremely useful for biological imaging applications.
This work was done with our former Master students Jordi Gomis and Pedro Martínez, and with Dr. Aarón Cofre after completing his PhD Thesis.
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)
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
Jueves, 3 de septiembre de 2020
i.moreno
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.
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: i.moreno@umh.es
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.
