Switchable Two-Dimensional Waveguiding Abilities of Luminescent Hybrid Nanocomposites for Active Solar Concentrators.

Passing from fossil energy sources to renewable ones, meanwhile answering the increasing world energy demand, will require innovative and low-cost technologies. Smart photovoltaic windows could fulfill our needs in this matter. Their transparency can be controlled to manage solar energy and regulate interior temperature and illumination. Here, we present the one-pot synthesis of polymer-dispersed liquid crystals (PDLCs), in which highly red-NIR phosphorescent transition metal clusters are selectively embedded, either in the polymer, in the liquid crystal, or in both phases. The PDLC matrix is used as a tunable waveguide to transfer the emitted light from nanoclusters to the edge of the device, where solar cells could be placed to convert it into electricity. Edge emission is obtained in both "off" and "on" states, with a maximum intensity for the scattering "off" one. These doped PDLCs showing photo-activity features and high stability under voltage represent key stepping stones for integration in buildings, displays, and many other technologies.

Injection and waveguiding properties in SU8 nanotubes for sub-wavelength regime propagation and nanophotonics integration.

We report photonic concepts related to injection and sub-wavelength propagation in nanotubes, an unusual but promising geometry for highly integrated photonic devices. Theoretical simulation by the finite domain time-dependent (FDTD) method was first used to determine the features of the direct light injection and sub-wavelength propagation regime within nanotubes. Then, the injection into nanotubes of SU8, a photoresist used for integrated photonics, was successfully achieved by using polymer microlensed fibers with a sub-micronic radius of curvature, as theoretically expected from FDTD simulations. The propagation losses in a single SU8 nanotube were determined by using a comprehensive set-up and a protocol for optical characterization. The attenuation coefficient has been evaluated at 1.25 dB mm(-1) by a cut-back method transposed to such nanostructures. The mechanisms responsible for losses in nanotubes were identified with FDTD theoretical support. Both injection and cut-back methods developed here are compatible with any sub-micronic structures. This work on SU8 nanotubes suggests broader perspectives for future nanophotonics.