One-dimensional photonic crystals as selective back reflectors

Using the sol–gel technology and dip-coating method involving the deposition of silica layers and titania layers, we have fabricated symmetrical structures with one-dimensional photonic crystals on both sides of glass substrates. For the structure with five bilayers (SiO2/TiO2) we have obtained the maximum reflectance of 0.967 for the wavelength λr=493 nm and full width at half maximum of the main reflectance peak of FWHM=185 nm. The fabricated structures have been analyzed theoretically with the application of the transfer matrix 2×2 method, allowing for complex refraction indexes for the component layers. The paper presents the applied theoretical model and the discussion involving the calculated and experimental results. Good agreement between the calculation and experimental results has been obtained. The elaborated photonic structures can be applied in solar light concentrators for photovoltaic systems.

► The theoretical model of optical structures with 1-D photonic crystals is presented.
► 1-D photonic crystals have been fabricated via the sol–gel dip-coating method.
► For five silica-titania bilayers the reflectivity of 97% has been obtained.
► The disturbance into the photonic structure results in change of its reflectivity.
► The theoretical results are in good agreement with experimental ones.