The Optical Society:
Researchers from #unicomplutense report in Optica how to create freestyle laser traps that can confine single and multiple microparticles in a large variety of 3-D curved shapes such as spirals, knots, waved rings and polygons. 

Their versatility and easy control of optical forces open up new perspectives for study of particle dynamics and design of light driven micromotors. This optical technology has also potential applications in optofluidics, laser micromachining and microbiology. 

José A. Rodrigo and Tatiana Alieva, "Freestyle 3D laser traps: tools for studying light-driven particle dynamics and beyond," Optica 2, 812-815 (2015)


Main research lines:

- Holography and development of new holographic materials 

- Green holography

- Holographic Optical Elements (HOE) with high performances

- Phase-space optics: Beam characterization and phase retrieval

- Optical microscopy toward quantitative imaging

- Holographic optical tweezers

- Optoelectronic devices for telecommunications and bio-sensing 

Optical coherenscopy based on phase-space tomography

Alejandro Cámara, José A. Rodrigo, and Tatiana Alieva Opt. Express 21, 13169-13183 (2013) 
Partially coherent light provides attractive benefits in imaging, beam shaping, free-space communications, random medium monitoring, among other applications. However, the experimental characterization of the spatial coherence is a difficult problem involving second-order statistics represented by four-dimensional functions that cannot be directly measured and analyzed. In addition, real-world applications usually require quantitative characterization of the local spatial coherence of a beam in the absence of a priori information, together with fast acquisition and processing of the experimental data. Here we propose and experimentally demonstrate a technique that solves this problem. It comprises an optical setup developed for automatized video-rate measurement and a method –phase-space tomographic coherenscopy– allowing parallel data acquisition, processing, and analysis. This technique significantly simplifies the spatial coherence analysis and opens up new perspectives for the development of tools exploiting the degrees of freedom hidden into light coherence. 


A Volume Holographic Sol-Gel Material with Large Enhancement of Dynamic Range by Incorporation of High Refractive Index Species

F. del Monte, O. Martínez, J. A. Rodrigo, M. L. Calvo, P. Cheben Adv. Mater. 18, 2014–2017 (2006)   DOI: 10.1002/adma.200502675  
In this work, a new generation of photo-polymerizable glass incorporating High Refractive Index Species (HRIS) was developed, based on Zr isopropoxide, gelated with metha-crylic acid and incorporated at a molecular level. This photomaterials exhibits high diffraction efficiency (near 100%), very low scattering due to the nano-composition structure, and very high refractive index modulation. For the first time, to the best of our knowledge, it was achieved a refractive index modulation in a holographic grating recording in such a photomaterial of 10-2.  


Rapid quantitative phase imaging for partially coherent light microscopy

José A. Rodrigo and Tatiana Alieva


Partially coherent light provides promising advantages for imaging applications. In contrast to its completely coherent counterpart, it prevents image degradation due to speckle noise and decreases cross-talk among the imaged objects. These facts make attractive the partially coherent illumination for accurate quantitative imaging in microscopy. In this work, we present a non-interferometric technique and system for quantitative phase imaging with simultaneous determination of the spatial coherence properties of the sample illumination. Its performance is experimentally demonstrated in several examples underlining the benefits of partial coherence for practical imagining applications.  


Gyrator transform: properties and applications

José A. Rodrigo, Tatiana Alieva, and María L. Calvo  Optics Express, Vol. 15, Issue 5, pp. 2190-2203 (2007)  
In this work we formulate the main properties of the gyrator operation which produces a rotation in the twisting (position - spatial frequency) phase planes. This transform can be easily performed in paraxial optics that underlines its possible application for image processing, holography, beam characterization, mode conversion and quantum information.As an example, it is demonstrated the application of gyrator transform for the generation of a variety of stable modes.


Programmable two-dimensional optical fractional Fourier processor

José A. Rodrigo, Tatiana Alieva and María L. Calvo  Optics Express, Vol. 17, Issue 7, pp. 4976-4983 (2009) 
A flexible optical system able to perform the fractional Fourier transform (FRFT) almost in real time is presented. In contrast to other FRFT setups the resulting transformation has no additional scaling and phase factors depending on the fractional orders. The feasibility of the proposed setup is demonstrated experimentally for a wide range of fractional orders. The fast modification of the fractional orders, offered by this optical system, allows to implement various proposed algorithms for beam characterization, phase retrieval, information processing, etc. Selected as Image of the week in OSA (6 April 2009). 


Generation of femtosecond paraxial beams with arbitrary spatial distribution

Ó. Martínez-Matos, José A. Rodrigo, M. P. Hernández-Garay, J. G. Izquierdo, R. Weigand, M. L. Calvo, P. Cheben, P. Vaveliuk, and L. Bañares  Optics Letters, Vol. 35, Issue 5, pp. 652-654 (2010) 
We present an approach to generate paraxial laser beams with arbitrary spatial distribution in the femtosecond time regime. The proposed technique is based upon a pair of volume phase holographic gratings working in parallel arrangement. It exploits the spatial coherence properties of the incoming laser beam in a compact and robust setup that mitigates angular and spatial chirp. The gratings were recorded in a photopolymerizable glass with a high optical damage threshold and a large optical throughput. Setup performance is studied and experimentally demonstrated by generating Laguerre–Gaussian femtosecond pulses. Selected as Image of the week in OSA (March 2010).