Optical chaos and hysteresis in a laser-diode pumped Nd doped fibre laser

Modulated pumping of a Nd3+doped silica monomode fibre laser has been investigated experimentally. For small modulation depths the laser exhibits a resonance at the relaxation oscillation frequency, providing pulses of a few microseconds duration at a repetition rate in the region of 10 kHz, dependent on the average pump level above threshold. As the pump modulation depth is increased, hysteresis is observed as a function of modulation frequency, along with optical bistability. For further increase in modulation depth, optical chaos and period doubling are observed. Gain-switching has also been demonstrated