DISPERSIVE SELF-Q-SWITCHING IN SELF-PULSATING DFB LASER

Self-pulsations reproducibly achieved in newly developed lasers with t wo distributed feedback sections and with an additional phase tuning s ection are investigated. The existence of the dispersive self-Q-switch ing mechanism for generating the high-frequency self-pulsations is ver ified experimentally for the first time, This effect is clearly distin guished from other possible self-pulsation mechanisms by detecting the single-mode type of the self-pulsation and the operation of one secti on near the transparency current density using it as a reflector with dispersive feedback, The operating conditions for generating this self -pulsation type are analyzed. It is revealed that the required critica l detuning of the Bragg wavelengths of the two DFB sections is achieve d by a combination of electronic wavelength tuning and current-induced heating, The previous reproducibility problems of self-pulsations in two-section DFB lasers operated at, in principle, suited current condi tions are discussed, and the essential role of an electrical phase-con trol section for achieving reproducible device properties is pointed o ut. Furthermore, it is demonstrated that phase tuning can be used for extending the self-pulsation regime and for optimizing the frequency s tability of the self-pulsation, Improved performance of the devices ap plied as optical clocks thus can be expected.