Dynamic features of a non-polarized Erbium-doped fiber ring laser subjected to external cavity-loss modulation

Abstract

An experimental study of an Erbium-doped fiber ring laser subjected to external cavity-loss modulation using a loudspeaker as the modulator has been carried out and analyzed via modulation of the driving amplitude and frequency in the range of 1–20 kHz. The linear and non-linear (chaotic) dynamical behaviors have been observed from the bifurcation, time domain and frequency domain diagrams presented. The bifurcation diagram showed that the loss modulated laser is more sensitive to the acoustic wave generated from the loudspeaker when the driving amplitude is < 200 mV and < 1000 mV (< 16.5 mW and < 82.5 mW optical power). At driving amplitudes of 500 mV – 1000 mV (41.25 mW – 82.5 mW optical power), the ring laser system behaves like a damped non-linear oscillator. Optical bi-stability was also observed in the bifurcation diagrams near or exactly at the fundamental resonance frequency and first super harmonic resonance frequency. The availability of different control parameters during external cavity-loss modulation in an Erbium doped fiber laser makes the study of its non-linear response features easy in a very precise way. The control parameters considered in this paper are the driving amplitude and the modulation frequency.