Tandem Binary Structures for Increased Coupling Efficiency of Laser Beams

Binary phase gratings have been investigated for use as beam splitters (1), multiplexers, and shapers (2). More recently, binary phase gratings have been used as beam couplers (3), coupling a large fraction of the outputs from an array of semiconductor lasers into a single gaussian output. The binary element is used to both split and combine the electric field inside of a complex external cavity. This technique overcomes the output power limitation of optical facet damage from single laser diodes.