FIBER COUPLED LASER DIODE MODULE ALIGNMENT

Subject of Research. The paper presents the results of the laser diode module optical system alignment, which includes three steps: the laser diode radiation collimation, the laser beams multiplexing from three sources and the radiation input into the optical fiber. The laser diode module optical system with a fiber output is realized as a stepped configuration of sources position with a height shift of laser diodes relative to each other by 1.6 mm. Semiconductor laser diodes with Fabry-Perot resonator and peak generation wavelength of 1020 nm are used as radiation sources. The core diameter of the output multimode quartz optical fiber is equal to 400 μm and the numerical aperture is NA 0.22. Method. The method of spatial multiplexing for laser beams from three laser diodes in a continuous-wave mode was implemented. The residual divergence and deviations control of the optical axes in each channel were carried out by measuring the laser beam profiles in two sections with the beam profile meter displaced strictly along the laser beams propagation axis by 100 mm. The radiation input efficiency into the optical fiber was determined by measuring the radiation power before entering the laser beam and at the output from the optical fiber. Main Results. The maximum output power of the laser diode module prototype is 19.65 W. The loss reduction is achieved owing to the application of anti-reflective coatings on the lenses and a highly reflective coating on the mirrors, taking into account the spectral composition of the radiation and the angle of incidence of the laser beams. Practical Relevance. The implemented assembly method can be used to manufacture higher output power laser diode modules, including more than three laser diodes without reduction in effectiveness. The developed micro-optical component positioning test bench allows for high-precision alignment of lenses and mirrors, and optical fiber coupling of optoelectronic devices.