Abstract

The unusual temporal dynamics of a semilinear optical coherent oscillator based on tin hypothiodiphosphate crystal (Sn₂P₂S₆, SPS) is described. The periodic non-harmonic modulation of the oscillator output intensity is revealed, with the pulse duration that depends on the overthreshold coupling strength and grating decay times. The pulse width changes in a wide range, decreasing closer to the threshold of oscillation. It is proved experimentally that every next pulse in a sequence is π-shifted in phase with respect to the previous one while within each pulse the phase of the oscillation wave is constant. This suggests the analogy of the observed behavior to the optical multivibrator. The origin of this phenomenon nests in competition of two species of movable charge carriers in formation of the space charge grating.

© 2003 Optical Society of America