Threshold, time, and spectral characteristics of a fiber laser

The time characteristics and spectral composition of the emission were determined for a fiber laser with a core doped with 6 wt.% Nd₂O₃. The study was carried out at the stimulated emission threshold as well as below and above it. In the subthreshold stage the emission spectrum of the active glass fiber narrowed to a width less than 100 Å and the pulse duration decreased. At the threshold pumping energy the stimulated emission was quasicontinuous (pulse duration Δτ = 75–200 μsec) and the half-width of the spectrum was Δλ < 0.017 Å. All the known time and spectral characteristics of the stimulated emission from solids were exhibited in a simple manner by the investigated glass-fiber laser.