We examine the behavior of self-pulsating laser diodes when injected with periodic optical signals. We experimentally and theoretically investigate the phase difference between the injected optical signal and the synchronized self-pulsating laser diode emission. We explore the phase difference dependence on detuning between the laser free-running self-pulsation frequency and the applied signal frequency, and on the injected signal power. The determined sensitive dependence of the phase difference on these factors has important consequences when self-pulsating lasers are used as optical signal processing elements in all-optical communication networks, where such sensitivity may lead to timing problems. © 1996 American Institute of Physics. ͓S0003-6951͑96͒02625-3͔The physics of nonlinear oscillators interacting with applied signals is a problem that has long been of intense interest.1-4 Laser diodes are particularly appropriate for investigating such phenomena as they are a relatively well understood model system for studying nonlinear dynamics and there is fundamental interest in understanding active nonlinear optical system behavior when perturbed by incident optical signals.5 A less esoteric, but nonetheless urgent, applied interest in these matters is driven by telecommunications as the increasing sophistication of high bandwidth fiber optic networks will ultimately demand high speed optically transparent systems. While existing networks are not yet alloptical and contain electronic elements that carry out specific functions such as routing and switching, it is becoming increasingly apparent that such electro-optical conversions will place severe limitations on the bandwidth of future networks. All-optical networks hold the key to communications that will be high-speed, high-volume, and more widespread than ever before, especially given the market driven constraints of effective utilization of the installed infrastructural base. Given these demands and constraints, all-optical alternatives are being sought to many functions currently performed by electronic devices in communication networks. Selection and development of these all-optical networks requires understanding of the interaction of light with active optical media; for example, in wavelength division multiplexing using semiconductor optical amplifiers 6 and in signal processing using self-pulsating laser diodes ͑SP LDs͒.7 In this letter, we examine the behavior of self-pulsating compact disk ͑CD͒ laser diodes when synchronized to externally injected optical signals. We examine the mechanism by which optical synchronization occurs and show how our numerical and experimental results can be explained on the basis of this mechanism. Calculations are found to be in excellent agreement with experimental results.SP LDs using complex, multisection devices have been shown to carry out function such as all-optical synchronization and clock extraction at high speeds. 7,8 However, future low cost networks may require simpler structures with which to implement such...

Abstract-We investigate both experimentally and theoretically the behavior of pulse jitter in compact disk (CD) self-pulsating lasers that have been synchronized to an applied periodic electrical signal. Our investigations reveal that pulse-to-pulse jitter in a synchronized laser is almost entirely unchanged from that in an unsynchronized laser under the same bias conditions. The major effect of synchronization is the suppression of long term jitter.

No abstract

We investigate optical synchronization with frequency multiplication and division of self-pulsating laser diodes. Using a simple rate equation model to describe self-pulsation we show that synchronization with frequency multiplication can be accompanied by large variations in the period of the emitted laser pulses over the injected pulse cycle. These variations are not obvious in the frequency domain treatment of synchronization. By applying a frequency division synchronizing signal to our model, we also show that the sensitivity of the phase difference between the injected signal and laser emission to power increases with increasing frequency division ratio and leads to the presence of power synchronization ranges.

The synchronisation mechanism of selfpulsating laser diodes is determined and it is shown how this results in a frequency-dependent phase difference between the electrical input and optical output. The time-to-lock of the electrical input to the optical output is examined, particularly with regard to the importance of the initial phase difference between the signals. The effect of synchronisation on timing jitter in selfpulsating lasers is also investigated.