Study on high power semiconductor laser arrays and output beam shaping

Abstract

Semiconductor Lasers (also known as Laser Diodes, LDs), have many unique properties and advantages and found wide applications in variouse fields. The super high conversion efficiency of high power single emitter semiconductor lasers and their arrays, commonly achievable values of them being in the range of 50%-80%, makes them particularly suitable for applications as the ideal pumping source for solid state lasers and also as widely used in material processing and medicine. Yet semiconductor lasers also have shortcomings, the poor beam quality of multi-mode semiconductor lasers and laser arrays usually severely restricted their applications. The present paper mainly addresses the semiconductor laser arrays design and fabrication technologies, with particular emphasis placed on the beam shaping principles and methods. The high power semiconductor lasers in the wavelength range between 800nm and 1100nm have been reviewed and analyzed. The topic of the electrical-to-optical conversion efficiency enhancement has been addressed in some detail. The high power single emitter lasers and LD bars have been fabricated and their performance characterized. The beam divergences of LDs in the vertical and parallel directions have been addressed and analyzed. The beam collimation has been analyzed and experimentally performed for the single emitter and LD bars. Beam combining methods and fiber coupling have been summarized and experimentally verified, with specific efficiency data for beam combining and fiber coupling being presented and analyzed.