Side-pumping of double clad fiber laser with a non-fusional fiber coupler

A non-fusional fiber coupler for high power double clad fiber lasers is demonstrated with optical adhesive technique. The fiber coupler is fabricated by polishing a non-doped single-clad fiber at a bevel angle and then adhering the single clad fiber to the doped double clad fiber with optical adhesive. The pumping light is launched through the single-clad fiber to the doped double-clad fiber and coupling efficiency of 90% can be achieved. It is found that coupling efficiency will decrease sharply when the bend is very near the coupling point and the optimum coupling angle depends on the fiber numerical aperture. Finally, laser radiation is demonstrated with a Nd-doped double clad fiber in low pumping regime.