Achromatization of solar concentrator thanks to diffractive optics

Refractive solar concentrators suffer from important chromatic aberration. To enhance solar cell
performance and increase the concentrating ratio, we propose an hybrid (diffractive/refractive) lens which allows a more uniform flux density and an achromatized (in the sense of achromatic doublet) illumination of the cell. To solve the problem of high diffraction efficiency, we turn to multilayer diffractive lenses to have broadband high diffraction efficiency optimized on solar spectrum. Rigorous coupled wave analysis simulations were performed in order to check the validity of scalar theory, they led to a new order of magnitude for the ratio period/wavelength
which has been found to be around 100 in place of 10.