Tunable Erbium: Ytterbium Fiber Fabry-Perot Micro Laser

Abstract

Erbium fiber lasers emitting in the 1.55um wavelength region have been under intensive research for applications in telecommunications, spectroscopy and sensors. To ensure single frequency operation, fiber lasers constructed with either Fabry-Perot cavities or ring cavities usually require wavelength filtering components such as external gratings [1], in-fiber gratings [2] and Fabry-Perot filters [3]. Wavelength tuning can subsequently be achieved by filter adjustments. Recently a microchip erbium:ytterbium (Er:Yb) phosphate-glass laser has achieved single-mode operation in a 200um Fabry-Perot cavity without additional filtering [4]. Here we report a compact tunable single-mode fiber laser using a novel combination of an Er:Yb phosphate-glass fiber (developed under contract to Amoco Technology Company) within a fiber Fabry-Perot (FFP) cavity [5]. Attractive features of Er: Yb phosphate glass include efficient pump absorption at 980nm by the Yb ions and a large stimulated-emission cross-section for the Er. FFP technology allows fabrication of very short cavities ( ~ 8um) and continuous wavelength tunability with low loss. Here we demonstrate the shortest Er: Yb phosphate-glass FFP laser ever reported, having a 100um cavity length and a continuous wavelength tuning range over 4.52nm, limited only by the sharp gain peak.