Experimental research of fiber coupling based on mini-bar

The paper investigates fiber coupling based on mini-bar. The mini-bar we packaged can deliver 60 W output power when the operating current is 60 A, and its central wavelength is 973.7 nm with the FWHM of 4.16 nm. The smile of this mini-bar is 0.57 m. Analysis on the characteristic of slow axis collimation shows the principle of how to choose the appropriate slow axis collimator. The divergence of the mini-bar after slow axis collimation is 47.6 mrad. The computation of beam parameter product reveals that the output laser can be directly coupled into a fiber with the core diameter of 600 m. Fiber coupling experiments based on the mini-bar have been performed. The transmission efficiency of collimator and fiber coupler is 83%-85%, the fiber coupling efficiency is 80%-93%, and the system optical-optical efficiency is over 72%.