Lasing at 2.1 µm pumped by a simultaneous-gain clad laser.

We obtained lasers based on the simultaneous-gain clad pump laser in a fluorotellurite fiber. Using a secondary suction method, we prepared a fluorotellurite double-clad preform with a Ho-doped core surrounded by a Tm-doped inner cladding, which we then drew into fibers. Tm ions generate a 1.94 µm laser by pumping the inner cladding with a 1570 nm fiber laser. This is followed by further pumping of the Ho-doped core, and a 2.06 µm laser is obtained. Our results validate cladding simultaneous-gain feasibility of producing core lasers in a fluorotellurite fiber.