Abstract

The first experimental observation of chaotic behavior to our knowledge is reported for an external cavity semi-conductor laser with AR-coating on one laser facet (residual reflectivity <0.1 %) and an intracavity étalon. As the cavity is detuned, the laser oscillates in a narrow single external cavity mode (linewidth less than 2 MHz, which is limited by the resolution of the equipment) or in multiple external cavity modes, depending on the cavity detuning from the resonance center of the étalon. In the latter situation, undamped relaxation oscillation and beating between external cavity modes are observed in the intensity noise spectrum. Quasiperiodicity and chaos occur sequentially by changing the cavity detuning, interrupted by frequency locking. The optical spectra show that symmetry breaking takes place as instability occurs. Similar phenomena have been observed as the pump current is changed. The mechanism for the instability in this system is postulated to be the inter action between the beating of multiple cavity modes and the undamped relaxation oscillation in the nonlinear laser medium.

© 1992 Optical Society of America