Er3+/Yb3+ co-doped bismuthate glass and its large-mode-area double-cladding fiber for 1.53 μm laser

Abstract

Er3+/Yb3+ co-doped large-mode-area double-cladding fibers based on Bi2O3-GeO2-Ga2O3–Na2O–CeO2 glass material were fabricated using a rod-in-tube method. Due to the low core numerical aperture (NA = 0.057), the prepared fiber can operate in single-mode regime with a cut-off wavelength of ∼1.49 μm while its core diameter reaches 20 μm. Based on the measured absorption spectrum, the spectroscopic parameters of Er3+/Yb3+ co-doped core glass were calculated by Judd-Ofelt theory. Relatively large spectroscopic quality factor (χ = 3.139), spontaneous transition probability (266.58 s−1) and radiative lifetime (3.75 ms) indicate the core glass has good radiation characteristics. Moreover, under 980 nm excitation, the strongest 1.53 μm emission is achieved in core glass while the doping concentration ratio of Er3+/Yb3+ is 1.0 mol%: 2.5 mol%. And the maximum emission cross section is calculated to be 8.2 × 10−21 cm2 at 1532 nm by McCumber theory. Finally, a stable laser output at 1535.4 nm is achieved in a 50 cm long as-drawn Er3+/Yb3+ co-doped fiber, yielding a maximum laser output power of 93.64 mW and a slope efficiency of 11.75%. The excellent optical properties indicate the prepared Er3+/Yb3+ co-doped fibers have potential applications for 1.53 μm band high power fiber laser.