Redirection Waveguide having Discrete Translational Symmetry for Photovoltaic Systems with Solar-Cell Units Placed at the Periphery

Abstract

We have investigated a new type of redirection waveguides for concentration solar-cell systems. The solar cell units are to be placed in the peripheral region of the waveguide. The redirection waveguide converts three-dimensionally propagating (3D) photons into 2D photons that propagate in a planar waveguide which serves as the mainstream of the redirection waveguide. In this new type, the cladding layer on one side of the planar waveguide, not being spatially continuous, tangentially touches the core of the planar waveguide which, having an open geometry, is connected, through tributary waveguides, to the bottom plane where the 3D-photons come in vertically. Based on simulations, we have shown not only that good mainstream-to-mainstream propagation of light-wave can be obtained but also that the light propagation from the tributary waveguides to the mainstream is well done. We also have confirmed that light-waves from the tributary waveguides are well merged with those from the mainstream waveguide at the junction of the cores of the mainstream and the tributary waveguides. Light-waves injected from tributary waveguides propagates well in the core of the mainstream waveguide passing those junctions. The light-wave merging can be fulfilled in the waveguide with the discrete translational symmetry. Photons are shown to be well conveyed in the new waveguide losslessly for a distance of ~1 mm. The redirection waveguide is promising for the concentration photovoltaic systems with solar-cell units placed at its periphery.