Fiber coupled diode laser module for laser processing by polarization multiplexing

Single emitter diode laser has better beam quality and longer lifetime as compared with a diode laser bar. However, its application to the material processing is limited by its lower output powers. To improve the output power of the single emitter diode laser, this paper proposed an optical fiber coupling method for single emitter diode lasers based on the polarization multiplexing. Firstly, 16 single emitters were divided into two laser groups, and the laser beam from the two groups was combined into one by spacial multiplexing technology. Then the beam was combined by polarization multiplexing again. Finally, a focusing system developed by ourselves was used to couple the combined beam into an optical fiber to improve the output power of the optical fiber coupling module. Experimental results show that the laser output of the module can reach 67 W from a fiber with a fiber core of 200 μm and a Numerical Aperture (NA) of 0.2 when the working current is 5.8 A. Moreover, the coupling efficiency of the module has reached 84%. This high power LD module can meet the requirements of plastic processing in power and beam quality.