Research On Optical Label Processing In Optical Packet Switching

Optical packet switching(OPS), which combines the high-speed optical signal processing and the high multiplexing efficiency of the packet switching, is an effective method of connecting seamlessly the high bit-rate optical transmissions and an important part of all-optical networks. Optical label processing (OLP) is one of the key technologies in OPS and the premise of realizing OPS. This dissertation makes deep investigations into the OLP technology by searching new schemes and improving the existing methods. The methods including theoretical analysis, simulations and experiments are adopted in the dissertation.The scheme of optical subcarrier label has the advantage of easily separating the label and payload, but the bit-rate upper bound of the payload is limited by the subcarrier frequency. In this dissertation, a novel optical packet with non-return to zero (NRZ) label and duobinary carrier-suppressed return-to-zero (DCS-RZ) payload is proposed to solve the disadvantage of optical subcarrier label. The optical power spectra of the label and payload are divided as the same as the scheme of optical subcarrier label, but the bit-rate upper bound of the payload is disappearing. The proposed packet, which has very good characteristics of chromatic dispersion and nonlinearity tolerance, can be transmitted in the long-distance fiber. The contrast ratio and BER performances of using optical filter to separate the label and payload are studied in theory and in the simulation. The research results can benefit the optimal design of the optical filters. On the study of the interference between the residual labels and the new label, the BER performance is severely devastated by the interference. A double-frequency label scheme is proposed to solve the interference successfully.High chip-rate optical code (OC) label has short label length but makes it difficult to manufacture the encoder and decoder. A scheme which adopts low chip-rate but no extra label length is proposed in this dissertation. The OC label is phase-shift keying (PSK) modulated on the amplitude-shift keying (ASK) modulation payload. The label detection performance under the interference of the payload is studied in theory and in the simulation. The research results show that the label BER performance can be improved by increasing the code length or the bit-rate ratio of the payload to the label.The advantage of OC label is to recognize the label in optical domain and the disadvantage is the difficulty of erasing the label. In this dissertation, the OC label is proposed to be modulated on the optical subcarrier. The scheme not only maintains the all-optical label processing but also simply realizes the label extraction by using optical filter. The generation of single-band subcarrier and the optical power distribution on the optical carrier and subcarrier are studied in theory and in the simulation. The feasibility of separating the label and payload by using optical filter is proved by simulation.The number of OC label is limited by the amount of the available OCs. A code and time-slot two dimensional OC (2D-OC) label is proposed to expand the OC label number in this dissertation. The BER formula of 2D-OC label is obtained. The OPS experiment is performed by adopting the proposed 2D-OC label.The optical encoding directly on the payload is another OC label. A switching structure based on two-stage optical switch is proposed in the dissertation. The BER formula of Gold sequence is obtained by correcting the reported formula and taking the polarization into account. The multi-hops BER is studied based on the BER formula in the switching node. A load-balancing algorithm is proposed, which formulate the node weight with BER and the label utilization.For overcoming the problem of erasing the bit-serial label, an OC-embedding optical packet format is proposed in the dissertation. The scheme feasibility is proved by simulation.For removing the optical power fluctuation of the input optical packets, semiconductor optical amplifier and Mach-Zehnder interferometer (SOA-MZI) structure and Fabry-Perot semiconductor optical amplifier (FP-SOA) are separately proposed to performance optical power equalization in the dissertation. The working principle is described and the feasibility is proved in the simulation. The corresponding parameter effects are studied.For solving the problem of ail-optically separating the bit-serial label and the payload, the scheme based on FP-SOA is proposed in the dissertation. The working principle is introduced and the simulation is performed. The parameter effects are studied.For realizing to decrease one pulse from the time-to-live (TTL) pulses, a scheme based on asymmetrical Mach-Zehnder interferometer (AMZI) and FP-SOA is proposed in the dissertation. The scheme feasibility is proved by simulation.For dealing with the slow carrier recovery in SOA and FP-SOA, the optical signal processing researches is performed on quantum dots semiconductor optical amplifier (QD-SOA). The schemes of optical hard limiter and optical power equalizer based on QD-SOA are studied by using the sectional simulation model.