HIGH-FREQUENCY OSCILLATIONS AND SELF-MODE LOCKING IN SHORT EXTERNAL-CAVITY LASER-DIODES

An effect of compound-cavity mode competition for a laser diode with a short external cavity is investigated analytically and numerically on the basis of a round-trip approximation for emitted photons in the ex ternal cavity. Due to the noncoincidence of the compound-cavity modes with possible frequencies of stationary lasing, such competition may c ause self-locking of two compound-cavity modes with deep high-frequenc y oscillations of the laser output for a short (typically less-than-or -equal-to 5 mm) external cavity. Simple analytical expressions for cri tical feedback parameters and the frequencies of self-oscillations are given, as well as a generalized diagram of different dynamic regimes of a short external-cavity laser, which shows these regimes of high-fr equency self-oscillations as well as coherence collapse instability. T he results may be considered a guideline for the design of high-speed laser diodes with an integrated passive cavity. In particular, such a device may be a very efficient pulse source in the microwave (> 20 GHz ) region.