Research On Fiber Coupling And Beam Shaping Technology Of Blue-Violet Laser Diode

In recent years,blue-violet laser diodes have been expanding in applications such as high-capacity optical data storage,laser display,laser medical,and advanced manufacturing,and have become one of the most popular light sources in 3D printing technology.Based on the requirement for the power and beam quality of blue-violet laser diodes in 3D printing applications,the paper studies the laser fiber coupling and beam shaping.Based on the comprehensive analysis of laser diode characteristics of luminescence,optical fiber characteristics and optical fiber coupling theory,this paper proposed two solutions: aspheric lens optical fiber coupling and cylindrical lens optical fiber coupling.The ZEMAX software was used to simulate the optical path design of the two schemes.The comparison results show that both the aspheric lens fiber coupling module and the cylindrical lens fiber coupling module can efficiently couple the 408 nm laser diode to the multimode fiber.In theory,more than 98% of the coupling efficiency can be achieved.However,the aspherical lens fiber coupling module had many advantages such as simple structure,small focusing spot,small module size,high transmission energy,etc.,which makes it more advantageous for fiber coupling.The aspheric optical fiber coupling experiment was completed by using 408 nm laser diodes,lenses,optical fibers and related components,and using optical fiber bundling technology.A blue-violet semiconductor laser fiber coupling module with a center wavelength of 408 nm and an output power of 8.12 W was obtained.With an air-cooled cooling system,the power instability was only 0.3% in 2 hours at an operating current of 1.3 A,and the total coupling efficiency was 83%.From the experimental data analysis,the actual fiber coupling efficiency is lower than the simulation result.In the process of collimation and focusing of the aspherical lens,the matching precision between the laser diode and the optical fiber is required to be very high,and the ultraviolet glue connection module is easy to deform,which causes the coupling position of the lens to shift and reduces the coupling efficiency.In order to improve the shaping effect of blue-violet laser beam,a shaping system consisting of a single collimating lens,a double-row fly's-eye lens(the aspect ratio is 16?9,the focal length is 26 mm)and a focus lens group was designed based on the illumination principle of geometrical optics and the design method of non-imaging optical system.The circular light field with large divergence angle was shaped into a rectangular light field with a size of 0.67 inches.The uniformity of light field can reach more than 86%,and the utilization rate of light energy is over 98%.The research shows that the blue-violet laser diode can realize the efficient and stable output of laser energy with simple and compact structure by using the aspheric lens fiber coupling technology.The output power of laser is greatly improved by using multi-fiber bunching technology,and the laser field is shaped into rectangular light field by using fly's-eye lens homogenizing system,which improves the uniformity of light field and ensures the utilization of laser energy.