High-concentration erbium-doped glasses, fiber amplifiers and lasers

Abstract

Upconversion coefficients in a new high-concentration erbium-doped tellurite glass were obtained a schematic study of experiments and modeling. The upconversion coefficient for ⁴I₁₃/₂ + ⁴I₁₃/₂ → ⁴I₉/₂ + ⁴I₁₅/₂ is found to be 2.74 x 10⁻¹⁸ cm³/s and for ⁴I₁₁/₂ + ⁴I₁₁/₂ → ⁴I₁₅/₂ + ²F₇/₂ is 1.09 x 10⁻¹⁸ cm³/s. The performance of high concentration Er³⁺+-Yb³⁺ -codoped phosphate fiber amplifiers and the performance of a high-power Er³⁺-Yb³⁺-codoped phosphate fiber laser were presented. From a 3.6cm-long fiber, 18 dB internal gain i.e. 5 dB/cm, for small signal input at 1535 nm, was achieved. With a cleaved facet as the output mirror, a fiber laser has been demonstrated from the same fiber with an output power of 33.8 mW at 1549.92 nm. A high slope efficiency of 40.2% was observed. Modeling results of gain and noise figure of four phosphate EDFAs with different lengths were presented with previous measured results. 34% erbium ions were found to be paired in our 3.5wt% erbium-doped phosphate fiber amplifiers. The onset of erbium concentration for pair induced quenching is suggested to be around 3wt% in phosphate fiber amplifiers.