A diode-laser-pumped, Er³⁺-doped fibre laser operating at 1.57µm

Abstract

Erbium-doped fibers show promise as stable narrow-linewidth laser sources and optical amplifiers operating in the third telecommunications window around 1.55µm Diode laser pumping is possible using the weak pump-band located at 807nm, although this band suffers severely from excited-state absorption (ESA), which reduces gain and pump efficiency. At the low pump power available from diode lasers the Er3+ behaves as a quasi four-level system. However, by codoping the core glass heavily with Yb3+, it is possible to excite the Er3+ ions indirectly using energy transfer. The Yb3+ provides an intense broad pump-band centered at 900nm, which reduces the effect of ESA. As a consequence of the resulting higher pump efficiency, the laser will oscillate at the required shorter wavelengths