Study On Control Technique Of Dual-wavelength Parallel Buffering For Optical Packet Switching

With the development of fiber communication, optical network becomes the basic platform in modern communication network. In the common network nodes, optical/electrical/optical(O/E/O) conversion process are necessary. As it needs time for optic-electronic elements and electronic cross switch to transfer signal and process it, there is an electron speed "bottleneck" in the network node. In order to overcome the "bottleneck", we should eliminate the O/E/O process, switch and process the optical signal directly. That means we have to develop all-optical communication network. As the all-optical packet switch (OPS) network can switch and process signal much faster and use the network bandwidth more efficiently. OPS network is potential for the ultra-fast optical networks.Substantively, OPS is a technique for buffering and transmitting. All optical buffer is an important component in the system of OPS. With the extensive application of WDM (wavelength division multiplexing), all optical buffer that only buffer single wavelength at present, will not fit the WDM any longer. So multi-wavelength all optical buffer become a significant research subject. In this paper, we studied on dual-wavelength parallel buffering by the improved Dual loop optical buffer that we have developed. As far as we know, we realize dual-wavelength buffering for the first time.The innovations of control technique of dual wavelength parallel buffering are as follows:1. The steady power drive circuit of semiconductor laser diode was developed.The drive circuit of semiconductor laser diode export steady optical power isdeveloped. It has solved the problem that the LD can not export steady power during the working temperature. The LD is used as the lamp-house in the buffering experiment.2. In dual wavelength parallel buffering, because of the random fluctuation of the combined power by different wavelength signals, the phase difference introduced by the cross phase modulation (XPM) of SOA fluctuates randomly too. But the characteristic curve in common use can not describe the gain saturation characteristics of SOA in saturation region exactly. Taking the absorption loss into account, we modify the gain characteristic curve of SOA and fit it with the experimental values. We also make a theoretical analysis for dual-wavelength buffering and propose a novel control technique for setting the power of control signal in order to minimize the fluctuation of the phase difference.3. Multi-circles buffering of 2.5Gbit/s dual wavelength packet is demonstrated in the experiment.