Propagation of partially coherent truncated polymorphic beams

The recently introduced concept of coherent polymorphic beam (PB), which is focused into a 2D light curve of arbitrary form with independently prescribed phase along it, is a fruitful generalization of the "perfect" ring vortex and opens up new perspectives in all-optical particle manipulation and light material processing. Its application for optical transport of micro/nano-particles has been experimentally demonstrated. However, the propagation of the PB has not been studied yet. In this Letter, we derive analytical expressions for the propagation of the truncated PB and its partially coherent counter-part through the first-order optical systems, in particular, the rotationally symmetric and twisting systems described by the fractional Fourier and Gyrator transforms, respectively. These expressions clarify the light-curve formation from a truncated PB and can be easily applied for the numerical simulation of the partially coherent PB propagatio

Ampliación y actualización de las prácticas del laboratorio de Instrumentación Biomédica buscando un aprendizaje y evaluación centrados en el estudiante

El objetivo del proyecto es el diseño de las prácticas de laboratorio para la asignatura Instrumentación Biomédica del Master de Física Biomédica. Se pretende mejorar el aprendizaje potenciando la participación activa y autonomía de los estudiantes. La falta de financiación económica se ha traducido en obtener como resultado del proyecto la redacción de guiones de prácticas que posibiliten el trabajo individual del alumno fuera del laboratorio dado el alto número de alumnos por puesto para llevar a cabo las prácticas. Estos guiones se han complementado con scripts en MatLab para analizar y procesar los datos obtenidos en el laboratorio así como datos obtenidos en diversas bases. Esta propuesta dió información sobre el progreso de los estudiantes en el aprendizaje cuando se utilizó el sistema de rúbricas tambien resultado de este proyecto

Programmable optical transport of particles in knot circuits and networks

© 2018 Optical Society of America. The Ministerio de Economía y Competitividad is acknowledged for funding the project TEC2014-57394-P.A freestyle single-beam laser trap allows for multi-particle optical transport along arbitrary open or closed trajectories with independent control of the all-optical confinement and propulsion forces exerted over the particles. Here, exploiting this manipulation tool, we propose and experimentally demonstrate an optical dynamic routing technique to assist multi-particle transport in knot circuits and networks exhibiting multiple crossing paths. This new functionality for optical transport enables the particle circulation in such complex systems handling traffic jams and making possible particle separation/mixing in them. It is important for the development of programmable particle delivery and other automated optical transport operations of interest in colloidal physics, optofluidics, biophysics, etc.Ministerio de Economia y Competitividad (MINECO)Depto. de ÓpticaFac. de Ciencias FísicasTRUEpu

Tailored optical propulsion forces for controlled transport of resonant gold nanoparticles and associated thermal convective fluid flows

Optofluidics: Light forces for controlling heat nanosources and fluid flows New opportunities for controlling the motion of laser-heated gold nanoparticles and the associated convection currents in the surrounding fluid are achieved by using tailored light forces. The procedure has been developed by Jose Rodrigo and colleagues at the Complutense University of Madrid. It is based on illuminating nanospheres at wavelengths that create resonant oscillations in surface electrons, a phenomenon known as plasmon resonance. This allows sufficient absorbance of light for the nanospheres to become a heat source. The tailored light forces gave fine control over the direction and speed of the hot nanospheres, both individually and in groups. The refined ability to form, merge and split clusters of nanoparticles could offer new applications in optofluidics-the science of controlling fluids and materials they contain with light. Noble metal nanoparticles illuminated at their plasmonic resonance wavelength turn into heat nanosources. This phenomenon has prompted the development of numerous applications in science and technology. Simultaneous optical manipulation of such resonant nanoparticles could certainly extend the functionality and potential applications of optothermal tools. In this article, we experimentally demonstrate optical transport of single and multiple resonant nanoparticles (colloidal gold spheres of radius 200 nm) directed by tailored transverse phase-gradient forces propelling them around a 2D optical trap. We show how the phase-gradient force can be designed to efficiently change the speed of the nanoparticles. We have found that multiple hot nanoparticles assemble in the form of a quasi-stable group whose motion around the laser trap is also controlled by such optical propulsion forces. This assembly experiences a significant increase in the local temperature, which creates an optothermal convective fluid flow dragging tracer particles into the assembly. Thus, the created assembly is a moving heat source controlled by the propulsion force, enabling indirect control of fluid flows as a micro-optofluidic tool. The existence of these flows, probably caused by the temperature-induced Marangoni effect at the liquid water/superheated water interface, is confirmed by tracking free tracer particles migrating towards the assembly. We propose a straightforward method to control the assembly size, and therefore its temperature, by using a nonuniform optical propelling force that induces the splitting or merging of the group of nanoparticles. We envision further development of microscale optofluidic tools based on these achievements