Efficient coupling system based on photonic waveguide for solar energy cell

Luminescent solar concentrators (LSCs) offer a simple approach to concentrating sunlight without the requirement of tracking the Sun. LSCs devices may shift the optical frequency through absorbing sunlight and then reemit photons with longer wavelength. Progressive research has revealed that current integrated photonic circuits have low efficiency in coupling free-space light into a waveguide and controlling the direction of the coupled light. Here, we present an efficient solar coupling device that allows normally incident light coupling from free space into a photonic Y-waveguide where it is trapped and propagate via total internal reflection to the output port. The design utilizes barium crown glass doped by uranyl (UO22+) and neodymium (Nd3+) material which absorbs the ultraviolet and blue portions of the solar spectrum but emits longer wavelengths. Finite-Difference Time-Domain (FDTD) numerical results show that the trapping efficiency of 76.7% can be achieved in this system. The proposed device has potential for vast application including the collection of solar light in enhancing the growth of several kinds of plant that require cold light at the appropriate wavelength, enhancing conversion efficiency of semiconductor solar cell, etc.