GaAs converter for high power laser diode

Transmission of electrical power in an optical form is of increasing interest. Many applications of this technique can have high conversion efficiency over 50%. An optical power transmission system consists of a laser (acting as a power source) and a photovoltaic device, eventually coupled by an optical fiber used as a waveguide. The fabrication technology developed for high efficiency solar cells can be used directly for the monochromatic applications. This paper describes efforts to develop a simple structure of GaAs solar cells for coupling to 814 nm laser beam. The cell is a p-Ga/sub 1-x/Al/sub x/As/p-GaAs/nGaAs structure on a n/sup +/-GaAs substrate, grown by liquid phase epitaxy with beryllium as acceptor dopant. The cell area is 7.1 mm/sup 2/ and the shadowing factor is 11.5%. The 814 nm light source is a 15-watts CW laser diode, directly beamed on the cell. In the present state of the authors' work, they report a 48.7% efficiency at 2.37 W/cm/sup 2/ input power and 44.5% at 11,3 W/cm/sup 2/. A 10 W conversion could be reached with a monolithic device of 2 cm/sup 2/ with this present laser diode.