Research On Optical Code Label Technology In Optical Packet Switching

Optical packet switching (OPS) is considered to be the ideal switching mode and development direction of optical network due to its attractive advantages, such as high flexibility and efficiency, transparency to data rate and format, and compatibility to IP service. Optical label is one of the key technologies in OPS, and several schemes have been proposed so far. Particularly, Optical code (OC) label is attracting increasing interest for its large code space and ability to realize all-optical processing. The superstructured fiber Bragg grating (SSFBG) and equivalent phase shift SSFBG (EPS-SSFBG) are adopted as the en/decoders in this thesis, and deep theoretical analyses and simulations, device design and experimental demonstrations are carried out to investigate the applications of OC-label technology in OPS network.The main researches accomplished in this thesis are as follows.(1) The SSFBG and EPS-SSFBG en/decoders are studied by theoretical analysis, numerical simulation and experimental demonstration. The coding theory and design method of SSFBG en/decoder are developed by Born approximation and matched filter theory, and then validated by numerical simulation on the basis of transmission matrix method (TMM). Several factors that may affect the en/decoding performance are analyzed, such as the amplitude of the refractive index perturbation, code length and pulse width of the light source. The principle of equivalent phase shift is introduced and verified by TMM simulation, and the influence of pulse width is discussed afterwards. An experiment is implemented to demonstrate the generation and recognition of 10-Gb/s OC-label by utilizing EPS-SSFBG en/decoder.(2) A scheme for transparent OC-label translation is proposed on the basis of SSFBG and EPS-SSFBG en/decoders. In the core OPS node, the short autocorrelation peak resulted by matched decoder is reused to generate the new OC-label, in order to achieve multi-hop transmission and switching. This architecture can also be used for data encryption to enhance the security and confidentiality of information. The simulation is implemented first to demonstrate the feasibility of this scheme, and some approaches to improve the system performance are presented. It is also found that the multi-stage en/decoding qualities based on EPS-SSFBGs are influenced seriously by light source, and proper pulse width should be selected to avoid the reflection of zero-order ghost grating, which will provide instruction for its application. Two sets of EPS-SSFBG en/decoders are employed in the experimental demonstration to realize the 10-Gb/s OC-label translation and recognition, which verifies the availability of this scheme.(3) A stacked OC-label scheme is applied for broadcast and multicast of optical packet. Several OC-labels are transmitted simultaneously, and they can be recognized separately due to the orthogonality of the OC-labels. This method won't produce extra overhead in the time domain, and can provide high processing efficiency. Furthermore, the number of stacked labels can be increased by utilizing codewords with fine property, which will be benefit for system scalability. The simulation is completed first, and then an experiment is carried out to realize the 5-Gb/s OC-label stacking and recognition with two sets of EPS-SSFBG en/decoders.