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We investigate a full-dielectric guided mode resonant photodiode. It has been designed to enhance the absorption by excitation of several resonances in the SWIR domain. The device consists of an InP/InGaAs/InP P-i-N heterojunction containing an active layer as thin as 90 nm on top of a subwavelength lamellar grating and a gold mirror. We successfully compared the electro-optical characterizations of individual pixels with electro-magnetic simulations. In particular, we observe near perfect collection of the photo-carriers and external quantum efficiency (EQE) of up to 71% around 1.55 μm. Moreover, compared with InGaAs resonator state-of-the-art detector, we show a broader spectral response in the 1.2-1.7 μm range, thus paving the way for SWIR low dark current imaging.

The design of metasurfaces able to efficiently control the polarization state of an electromagnetic wave is of importance for various applications. We demonstrate both theoretically and experimentally that plasmonic planar L-shaped antennas can induce a 90◦-rotation of the linear polarization of light with a nearly total efficiency in the infrared (3-5 µm). The nanoantenna geometry is engineered so that the polarization conversion occurs over a 1 μm-wide spectral band ([3.25-4.25] µm ) with a mean polarization conversion efficiency of 95 %. In order to validate a theoretical model describing the antenna behaviour, we investigate the polarization conversion effect as function of the incident and azimuthal angles.

Light trapping enhancement is a major research field in photovoltaics. Scarce and expensive resources for semiconductor material drive the research on light management in thin absorber layer. This paper reviews some of the known techniques, from back reflector to nanophotonic technologies such as nanowires or plasmonic-enhanced photovoltaic devices. Light trapping enhancement can reach ~100 fold and experimental demonstrations of device exceeding the ray optics limits have been reported.

Conventional light trapping techniques are inefficient at the sub-wavelength scale. This is the main limitation for the thickness reduction of thin-film solar cells below 500nm. We propose a novel architecture for broadband light absorption in ultra-thin active layers based on plasmonic nano-cavities and multi-resonant mechanism. Strong light enhancement will be shown numerically for photovoltaic materials such as CIGSe and GaAs. First experiments on ultrathin nano-patterned CIGSe solar cells will be presented.

New concepts for efficient light absorption in nanoscale metal-semiconductor-metal photodetectors are analyzed from both theoretical and experimental point of view. They are based on sub-wavelength metallic gratings which allows light confinement in tiny volumes (< 100 nm) close to electrodes (< 100 nm). Two photodetector structures are proposed: (i) a resonant-cavity-enhanced subwavelength metal-semiconductor-metal photodetector, and (ii) a nanoscale metal-semiconductor grating photodetector. External quantum efficiency as high as 9 % has been obtained in 40 x 100 nm2 cross-section GaAs wires, limited by fabrication technology. These results show promising features for highly efficient and ultrafast photodetectors.