Enhanced arc-induced core expansion for mode-field adaptation using a H2-loaded fiber

An efficient method to improve the efficiency of mode-field adaptation between two mismatched fibers with arcs and hydrogen-loading is proposed and demonstrated for the first time. By hydrogen-loading the fiber of a relatively smaller core, the dopant diffusion rate and the mode transition region length were significantly increased. These enhancements contributed to an abrupt diffusion rate difference at the intersection of the fibers and an adiabatic mode transition. For the mode-field adaptation of the two fibers that have a mode-field area ratio of 7.25, the transmission loss was reduced from -3.71 to -0.24 dB by an arc duration of approximately 10 seconds.