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

•An ASE light source with center wavelength of 1 µm was employed to excite a high-Q Yb/Er co-doped silica microsphere with the advantage of resisting the interference of vibration and temperature changes. A stable single-mode laser at approximate 1595 nm was generated due to the polarization insensitivity of the ASE light source. The maximum output power of WGM single-mode laser is −28.7dBm, the FWHM is 0.05 nm, and the SNR is 24.2 dB.•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 handle of the microsphere. The tuning range reached 190 GHz at our setup.•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.