Optical fiber coupling of high-energy density pulsed lasers for laser ignition

In order to improve coupling efficiency and maximal laser transmission energy density, lasers with Gaussian distribution and flat-top distribution were utilized to couple to optical fibers with different surface roughness. The coupling efficiency and damage threshold of the fibers were studied. The experiment results showed that for Gaussian distribution laser beam, optical fibers with higher degree of smoothness would get better coupling efficiency, but would suffer more damage inside the fiber. But for flat-top distribution laser beam, optical fibers with higher degree of smoothness would get both higher coupling energy and efficiency.