Abstract

Intensity pulsations of single-mode FIR lasers bear strong resemblance /1/ to those of the Lorenz model /2,3/ even though the additional coherences induced by the optical pumping would seem to require more complex models /3/. We have completed detailed measurements of intensity pulsations of different types (including periodic, period doubled, period-doubling chaos, period three, and "Lorenz-like" chaotic spirals) and have calculated phase portraits, dimensions and entropies of these signals for comparisons with results of numerical solutions of the model for a single-mode laser with a homogeneously-broadened two-level medium. As some features of the attractor dynamics, notably the phase dynamics of the electric field, cannot be determined from intensity measurements, we have used heterodyne methods to detect the electric field amplitude in real time from which we have determined the symmetry or asymmetry of the attractors, the nature of frequency modulation accompanying the intensity pulsations and the presence of switchings of the optical phase by π radians at the start of each new "Lorenz-like" spiral.

© 1988 Optical Society of America