The maximum tolerable amplitude backreflection coefficient <i>r</i><sub>ext,<i>c</i></sub> into a fiber distributed-feedback laser before the onset of instability has been investigated. <i>r</i><sub>ext,<i>c</i></sub> was found to decrease with increasing external cavity lengths up to ~320 m and to be proportional to the relative linewidth of the relaxation oscillation resonance. The tolerable length of Rayleigh backscattering standard telecom fiber was found to be 135–200 m. An observed degradation in the laser stability and slope efficiency at low pump powers is believed to be due to UV-induced saturable absorbers.
© 1999 Optical Society of America
Erlend Rønnekleiv, Oliver Hadeler, and Guillaume Vienne, "Stability of an Er-Yb-doped fiber distributed-feedback laser with external reflections," Opt. Lett. 24, 617-619 (1999)