In this work, we report using an optical tweezers system to study the light-matter interaction and gradient optical forces of porous silicon nanoparticles. The particles are fabricated by first electrochemically etching a multi-layer porous film into a silicon wafer and then breaking up the film through ultrasonic fracturing. The particles have average pore diameters ranging from 20-30 nm. The fabricated batches of particles have diameters between approximately 100- 600nm. After fabrication, the particles are size-sorted by centrifugation. A commercially available optical tweezers system is used to systematically study the optical interaction with these nanoparticles. This work opens new strategic approaches to enhance optical forces and optical sensitivity to mechanical motion that can be the basis for future biophotonics applications.
We report on the investigation of crossed-Bessel-beam and hybrid Bessel-Gauss configurations for optical trapping of
microscopic particles. The non-diffractive nature of the Bessel beam removes the need for high-NA optics. Crossed
beam configurations allow creating trapping volumes with small aspect ratio, in comparison to single-beam Bessel traps
that create wave-guide like structures. We present numerical simulations of said geometries and present experimental
data of in-situ Bessel beam forces on polystyrene beads as precursor to the realization of a random access Bessel trap.