All-optical tuning of the frequency of Yb3+/Er3+ co-doped microsphere WGM laser pumped by 1 µm ASE light source

Abstract

In this paper, the laser generated by Yb3+/Er3+ co-doped silica microspheres excited and tuned by amplified spontaneous emission (ASE) light source was studied. The adoption of ASE light avoids the synchronous adjustment of the coupling condition of the microcavity during broadband tuning process, and facilitates the actual application of the microcavity-based tunable laser. The stable single-mode laser at approximate 1595 nm was generated in the Yb3+/Er3+ co-doped silica microsphere due to the polarization insensitivity of the ASE light source with a center wavelength of 1 µm. For the all-optical modulation of laser mode, a thin layer of copper film was coated on the spherical crown of the microsphere by magnetron sputtering. Controllable heating of the microsphere and linear tuning of laser mode were realized through the absorption of ASE light by the copper film injecting from the stem of the microsphere. The tuning range reached 190 GHz.