A Thermal Diode Based on Nanoscale Thermal Radiation.

In this work we demonstrate thermal rectification at the nanoscale between doped Si and VO surfaces. Specifically, we show that the metal-insulator transition of VO makes it possible to achieve large differences in the heat flow between Si and VO when the direction of the temperature gradient is reversed. We further show that this rectification increases at nanoscale separations, with a maximum rectification coefficient exceeding 50% at ∼140 nm gaps and a temperature difference of 70 K.

Passive coherent beam combining of quantum-cascade lasers with a Dammann grating.

An external cavity using a binary phase grating has been developed to achieve coherent combining of five quantum-cascade lasers emitting at 4.65 μm. The grating phase profile is designed to combine five beams of equal intensities into a single beam with a good efficiency (~75%).

Real-time increase in depth of field of an uncooled thermal camera using several phase-mask technologies.

Imaging systems that combine a phase mask in the pupil and digital postprocessing may have better performance than conventional ones. We have built such a system to enhance the depth of field of an uncooled thermal camera. The phase masks are binary, their structures are optimized thanks to an image quality criterion, and they have been realized with three different technologies that give equivalent results.

Detailed analysis by Fabry-Perot method of slab photonic crystal line-defect waveguides and cavities in aluminium-free material system.

A single-line-defect low-loss photonic crystal waveguide based on a perforated GaAs membrane in an aluminium-free material system is demonstrated. The GaInP lattice is matched to GaAs as the cladding/sacrificial layer. Fabry-Perot resonances are analyzed to obtain the group velocity dispersion for a 1-mm long guide.