Hexagonal rare-earth-doped double-clad chalcogenide glass fiber with high absorption efficiency

Abstract

The difficulty in the preparation of high-quality rare-earth-doped double-clad chalcogenide glass fiber with high absorption of pumping energy is one of the major issues in the development of mid-infrared fiber lasers. In this study, we solve this problem by changing the inner cladding structure of the fiber. The absorption efficiencies of several typical inner cladding shapes were compared and analyzed by the ray tracing method. The result shows that the hexagonal inner cladding fiber has the best absorption efficiency. For the first time, we developed an Er3+-doped Ge-Ga-Sb-S double-clad chalcogenide glass fiber with a hexagonal inner cladding via the fiber extrusion method, and experimentally demonstrated a higher absorption efficiency in the fiber compared with those in the traditional circular double-clad fibers. Such a hexagonal double-clad chalcogenide glass fiber possesses the potentials for developing high-efficiency mid-infrared fiber lasers.