Experimental generation of Mathieu-Gauss beams with a phase-only spatial light modulator.

We present a novel method for the efficient generation of even, odd, and helical Mathieu-Gauss beams of arbitrary order and ellipticity by means of a phase-only spatial light modulator (SLM). Our method consists of displaying the phase of the desired beam in the SLM; the reconstructed field is obtained on-axis following a spatial filtering process with an annular aperture. The propagation invariance and topological properties of the generated beams are investigated numerically and experimentally.

Polarization gradient: exploring an original route for optical trapping and manipulation.

We report a study of the capabilities of an optical tweezer based on polarization gradient. We use a light polarization pattern that is able to simultaneously exert forces and torques in opposite directions depending on the particle's position. It allows to perform oscillatory displacements and control the sense of rotation of several particles inside a uniformly illuminated region.

Hollow spheres as individual movable micromirrors in optical tweezers.

We introduce the use of hollow micron-sized spheres with a finite-thickness glass shell as individual micromirrors operating by total internal reflection (TIR) when illuminated off-axis. We also demonstrated that this kind of spheres can be optically trapped and manipulated in two dimensions using a Gaussian beam in a conventional optical tweezers setup, which allows the precise positioning of the micromirrors at specific locations within a sample cell. This mirrors constitutes a new micro-tool in the context of the so called lab-on-a-chip.