A light coupler emitting a high power laser with a high beam quality and a fiber laser system including the light coupler is disclosed. The light coupler includes a first optical fiber bundle comprising a plurality of first optical fibers having either a single-mode core or a few-mode core and a second optical fiber, which guides multi-mode beams and is connected to the first optical fiber bundle. The optical fiber laser system includes a light coupler having a first optical fiber bundle comprising a plurality of first optical fiber having either a single-mode core or a few-mode core and a second optical fiber, which is connected to the first optical fiber bundle, is either a single cladding optical fiber or a double cladding optical fiber, and guides multi-mode beams, and one or more gain medium optical fiber, which is connected to the light coupler and emits light.