We show that the recombination energy of the direct band gap photoluminescence (PL) of germanium can be controlled by an external mechanical stress. The stress is provided by an apparatus commonly used for bulge or blister test. An energy redshift up to 60 meV is demonstrated for the room temperature PL of a thin germanium membrane (125 nm wavelength shift from 1535 to 1660 nm). This PL shift is correlated with the in-plane tensile strain generated in the film. A biaxial tensile strain larger than 0.6% is achieved by this method. This mechanical strain allows to approach the direct band gap condition for germanium which is of tremendous importance to achieve lasing with this material.
Plasmonic resonators are excellent candidates to control reflectance of functionalized substrates. Because of their subwavelength characteristic dimensions, they can even be used to modify the color of transparent glass plates without altering the transparency quality. Their spatial arrangement must be carefully chosen so that the plates don't produce nonspecular diffraction, whatever their spatial density. We compare here the response of silver
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