Frequency locking, quasiperiodicity, and chaos in modulated self-pulsing semiconductor lasers

A transition to chaos via quasiperiodicity is observed in the output of a directly modulated self‐pulsing semiconductor laser. By sweeping the frequency and amplitude of the current modulation, several frequency‐locked states (Arnol’d tongues) are mapped out directly. Good agreement with the predictions of a rate equation model is obtained.