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New paper in Applied Sciences about the generation of hybrid vector beams with a detuned q-plate


ASOur 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.


Viernes, 15 de mayo de 2020 Sin comentarios

New paper in OSA Continuum showing Bessel beams with tunable control through maximum phase modulation


getThumbnail.cfmOur 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.


Categories: International, Projects, Research Tags:

Martes, 12 de mayo de 2020 Sin comentarios

TecnOPTO organizes a workshop on ‘Structured Light, Polarimetry and Imaging’


Workshop

On November 25th, 2019 we organized a workshop entitled ‘Structured Light, Polarimetry and Imaging‘.

The workshop was held at the Institute of Bioengineering of UMH, and we could count with the participation of experts from different groups in Spain working in these related fields. The program can be viewed at the following link.

We thank all the participants and attendees to this extremely interesting and motivating reunion.


Martes, 26 de noviembre de 2019 Sin comentarios

New paper in OLEN analyzing the diffraction efficiency of stepped gratings in large phase modulation SLMs


OLENOur new publication is available in Optics & Lasers in Engineering, entitled Diffraction efficiency of stepped gratings using high phase-modulation spatial light modulators.

We study the diffraction efficiency of linear phase (blazed) diffraction gratings displayed onto SLMs that exhibit a large phase modulation range, reaching a maximum phase modulation of 8pi or 10pi radians. We analyse these effects for their important implications in the Nyquist limit for diffractive elements

The paper has been done in collaboration with our friends at San Diego State University.


Domingo, 3 de noviembre de 2019 Sin comentarios

Special Section in Optical Engineering about Spatial Light Modulators


A special section on Spatial Light Modulators (SLMs) – Devices and Applications will be published in the journal Optical Engineering. Ignacio Moreno and María Del Mar Sanchez-Lopez are Guest Editors of this special section of the journal, together with Prof. Andrew Forbes and Prof. Yoshio Hayasaky.

The following link leads to the journal Call for Papers.

The deadline for submitting papers is October 15th, 2019. See here the flyer of the OE special section on SLMs. OE-SLMs

 


Miércoles, 14 de agosto de 2019 Sin comentarios

David Marco and Julio César Quiceno present their results at IONS 2019, Barcelona, June 2019


In his talk entitled «Two-dimensional geometric phase vortex grating based on the optimal triplicator design», David presented the design and characterization of a liquid-crystal geometric phase diffraction grating that generates 3×3 diffraction orders with vortex beams of different topological charges, and showed the operation of this grating as a vortex detector. These results have recently been published in Optics Express: link to the paper.

Julio César presented a poster entitled “Hybrid vector beams generated by cascaded q-plates” where he demonstrated a q-plate-based optical system capable of generating a variety of hybrid vector beams, and showed the rotation of their polarization pattern when comparing the near field and the far field captures. This optical system is more compact than those based on SLMs whilst bearing a notable degree of versatility.

They have enjoyed the interesting conferences, scientific discussions and networking opportunities of this conference hosted by the OSA student chapter at ICFO and backed by the International OSA Network of Students. Link to the conference.

IONS

 

 


Domingo, 7 de julio de 2019 Sin comentarios

New paper in Optics Letters on breaking the Nyquist limit for diffractive lenses with high phase modulation displays


OL FIGWe published a new paper in Optics Letters entitled Encoding lenses with focal lengths lower than the Nyquist limit using high phase-modulation displays. In this work we show that focal lengths much lower than the classical Nyquist limit can be encoded onto spatial light modulators having a large phase-dynamic range.

Experimental results are included with a display showing 10π phase modulation reducing the Nyquist limit by a factor of about 1/10. We used a  Hamamatsu reflective LCoS device designed for use in the near infra-red (NIR) range, but operated with visible light in order to achieve such large modulation regimes.

The work has been done in collaboration with our friends at the Department of Physics of San Diego State University.


Jueves, 27 de junio de 2019 Sin comentarios

New paper in Optics Express about a geometric phase vortex triplicator grating


REDWe published a new paper in Optics Express entitled Optimal triplicator design applied to a geometric phase vortex grating. It shows a liquid-crystal diffraction grating based on the optimal triplicator design fabricated as a geometric phase element. We analyze the polarization properties of this special diffraction grating and then use embedded spiral phases to design geometric phase vortex diffraction gratings. The fabrication of a two-dimensional version of such a design is demonstrated using a micro-patterned half-wave retarder, where the phase distribution is encoded as the orientation of the fast axis of the retarder.

This proof-of-concept element is made of liquid crystal on BK7 substrate where the orientation of the LC is controlled via photoalignment, using a commercially available fabrication facility. Experimental results demonstrate the parallel generation of vortex beams with different topological charge and different states of polarization.

This work is part of the PhD Thesis of David Marco, and it has been done in collaboration with our friends Aarón Cofré and Asticio Vargas, from Universidad de La Frontera, Temuco, Chile.


Categories: Projects, Publications, Research, Thesis Tags:

Lunes, 6 de mayo de 2019 Sin comentarios

New paper in J. Opt. Soc. Am. B about the colors of a tunable q-plate


DzexHWoW0AAiN98Our new paper in Journal of the Optical Society of America B is entitled Using birefringence colors to evaluate a tunable liquid-crystal q-plate. Here we show a tunable liquid-crystal commercial -plate from the company Arcoptix, operative in the visible and near-IR range. We study its spectral and color birefringence properties under broadband illumination.

We first characterize the spectral retardance function of the device in a wide range from 400 to 1600 nm and determine how it changes upon applied voltage.

Then we evaluate the color transmission characteristics when inserting the -plate between crossed and parallel linear polarizers. These color properties agree with the trajectory in the CIExy chromaticity diagram as the applied voltage changes.

Finally, we demonstrate that a simple visual inspection of the transmitted birefringence color perceived when placing the -plate between crossed polarizers can be used to obtain a rapid estimation of the -plate retardance at given wavelength ranges.

This work is the first paper of the PhD Thesis of David Marco.


Categories: Projects, Publications, Research, Students, Thesis Tags:

Miércoles, 13 de febrero de 2019 Sin comentarios

Julio César Quiceno, from Universidad del Valle, Cali, joins TecnOpto


Dyz6KvlU8AAYqsiJulio César Quiceno, from Universidad del Valle, Cali, Colombia, will be visiting researcher at TecnOpto for a period of six months.

We will be working together in new projects related to vector beams.

Welcome to Elche!

 


Miércoles, 13 de febrero de 2019 Sin comentarios