Period-doubling cascades and chaos in a semiconductor laser with optical injection

We characterize the nonlinear dynamics of a semiconductor laser subject to optical injection. The key characteristics of measured optical spectra are reproduced in calculations based on a single-mode model that includes spontaneous-emission noise. The laser exhibits chaos over a bounded range of injection levels. As the chaotic regime is approached from both lower and higher injection levels, a period-doubling route to chaos is followed, although the route is obscured by spontaneous-emission noise. A new, bounded regime of period-doubling occurs for injection levels well above the region of chaotic dynamics. Optical injection strongly modifies the carrier-field resonance coupling frequency.