arXiv subjects

D. J. Broer

Publications and source records attributed to D. J. Broer.

3 recordsLinked to original sources

arXiv2011

Circular dichroism of cholesteric polymers and the orbital angular momentum of light

We explore experimentally if the light's orbital angular momentum (OAM) interacts with chiral nematic polymer films. Specifically, we measure the circular dichroism of such a material using light beams with different OAM. We investigate the case of strongly focussed, non-paraxial light beams, where the spatial and polarization degrees of freedom are coupled. Within the experimental accuracy, we cannot find any influence of the OAM on the circular dichroism of the cholesteric polymer.

physics.optics↗

arXiv2009

Fully reversible transition from Wenzel to Cassie-Baxter states on corrugated superhydrophobic surfaces

Liquid drops on textured surfaces show different dynamical behaviors depending on their wetting states. They are extremely mobile when they are supported by composite solid-liquid-air interfaces (Cassie-Baxter state) and immobile when they fully wet the textured surfaces (Wenzel state). By reversibly switching between these two states, it will be possible to achieve large control over the fluid dynamics. Unfortunately, these wetting transitions are usually prevented by surface energy barriers. We demonstrate here a new and simple design paradigm, consisting of parallel grooves of appropriate aspect ratio, that allows for a controlled, barrierless, and reversible switching of the wetting states upon the application of electrowetting. We report a direct observation of the barrierless dynamical pathway for the reversible transitions between the Wenzel (collapsed) and the Cassie-Baxter (suspended) states and present a theory that accounts for these transitions, including detailed lattice-Boltzmann simulations.

cond-mat.soft↗

arXiv2006

InP-based two-dimensional photonic crystals filled with polymers

Polymer filling of the air holes of Indium Phosphide based two-dimensional photonic crystals is reported. After infiltration of the holes with a liquid monomer and solidification of the infill in situ by thermal polymerization, complete filling is proven using scanning electron microscopy. Optical transmission measurements of a filled photonic crystal structure exhibit a redshift of the air band, confirming the complete filling.

physics.optics↗