Metal-coated fluoride glass fiber

We demonstrate a new design for active fluoride glass fibres in which a metal coating instead of a polymer coating is applied. A 2-μm-thick silver layer is fabricated chemically to the periphery of the fiber, that in this case is doped with Dy3+ ions, and coating lengths of up to 20 cm were produced. The temperature rise in the core of the fiber was accurately measured using a sensitive fiber Mach-Zenhder interferometer (MZI) employing a stabilised He-Ne laser. We use this setup to show that the metal coating can achieve a reduction in the fibre core temperature by up to 22% for low launched pump power levels. A basic two-dimensional model shows reasonable agreement with the experiment. This work paves the way for the development of active fluoride fiber applications in which reducing and stabilising the temperature of the fibre is critical.