Study On The Technology Of Generation And Transmission For Optical Packets Based On OFDM In Optical Label Networks

All-optical switching is the most promising switching technology for the future communication networks. It can provide the ability for transmission and processing of high speed and large capacity to break the "bottleneck" of information transfer. So it will adapt to bandwidth requirements for high-speed broadband services in a long time. In view of current development level of technologies and devices, combining the advantages of processing technologies of electronic devices, an optical packet switching technology based on the electronic and optical system has been proposed—optical label switching, which is the most effective way to achieve all-optical network. In this paper, based on such a research background, generation, swapping and transmission of optical labels and optical packets are researched by theoretical analysis, numerical simulation, and experimental verification, mainly including:Firstly, a novel optical packet transmission scheme, in which an optical orthogonal frequency division multiplexing (OOFDM) signal has been generated as a label, has been proposed and experimentally demonstrated. Orthogonal frequency division multiplexing (OFDM) can combat dispersion in optical communication. Using OFDM in optical label switching system, there will be so many advantages such as anti-dispersion, anti-interference and high spectral efficiency that can realize long-distance signal transmission. In the experiment, 10Gb/s OOK payloads and 2.5Gb/s OFDM labels are modulated on two optial carriers of different wavelengths by intensity modulations, respectively. And then optical packet were generated by coupling optical payloads and optical labels. After 40km single-mode fiber transmission, payloads and labels are separated by an interleaver, and then detected by the corresponding receiver. The experimental results show that payload signals and label signals can still be well restored after 40km fiber transmission of optical packet. Power losses are so little that the scheme is suitable for long-distance transmission. The scheme is simple and has the following advantages:payloads and labels are modulated separately, so there are no restrictions of the extinction ratio and crosstalks are not obvious. It is easy to realize combination and separation of payloads and labels.Secondly, a novel orthogonal optical labeling scheme based on orthogonal frequency division multiplexing (OFDM) singals and phase-shift keying (PSK) signals has been proposed and simulation demonstrated.2.5Gb/s OFDM label signals are generated by intensity modulation and 10Gb/s payload signals are generated by phase modulation. OFDM/PSK orthogonal modulation on the identical optical carrier is achieved and optical packet is produced. After single-mode fiber transmission, payloads and labels are received with the respective detection mode. OFDM signals can help to overcome the dispersion effect and PSK signals can suppress the non-linear effect effectively because of the constant intensity of PSK signals. Therefore, this orthogonal optical labeling scheme, will further realize efficient signal transmission. The feasibility of this scheme is proved by simulation and theoretical analysis. This scheme is characteristic of simple structure, high spectral efficiency and suitable for long-distance transmission.