| At present the combination of DWDM with OTDM techniques has gradually become the main part of backbone of modern communication networks,which is regarded as the development of the ultra-high speed,ultra high capacity and ultra long haul optical transmission communication networks.Optical transmission and optical switching are the two key aspects of optical communications.In this paper,supported by the key projects of National Natural Science Fondation "Research on PMD compensation and related infrastructure technologies in high speed optical communication systems","Study on all optical circuit switching technology" and National 863 project "Study on 160Gbit/s one pump multi-fiber optical transmission technology",we conduct a deep investigation into the theoretical and experimental research on the novel optical vestigial sideband(VSB) modulation formats,the increase of spectrum efficiency of OTDM,algorithm of grating fiber design and wavelength routing network applications.The main results achieved are as follows:1.The scheme of implimetation of optical vestigial sideband modulation formats with tunable uniform Bragg grating was proposed.The theoretical model of VSB-NRZ/RZ modulation system with optical bandstop filter was build.The main effects of EOP and the suppression ratio of sideband of VSB codes were analyzed induced by the parameters of optical filter.And then by negelecting the nonideal properties of DCF and CFBG,the differences of transmissions were analyzed in detail. A further analysis was made considering the effect of group delay ripple of CFBG in VSB transmission system.At last,an experiment of VSB modulation with tunable Bragg grating in all optical WDM network platforms was made to verify the feasibility of this proposal.2.For the first time,the scheme of the increase of spectrum efficiency of OTDM was investigated by employing matiching optical filter.The theoretical model of OTDM system based on picosecond pulse laser sources was build.The effects in time and spectrum domain of OTDM signals were discussed induced by these factors such as the difference of amplitude and vibration of amplitude and delay in each channel.The original proposal was made to increase the spectrum efficiency of OTDM by designing the matching filter of demultiplexing switching windows.Related experiments were made for the first time in which the 4×10Gbit/s OTDM signals were compressed by employing Arrey Waveguide Grating(AWG).Furthermore the clock extraction and demultiplexing of OTDM over 100 km transimsion were implemented as well.The experimental results show the increase of almost three times of spectrum efficiency comparing with the original OTDM singals which verified the feasibility of the scheme.3.A novel interpolation and searching algorithm was proposed,which designed and rebuild the optical bandpass and low dispersion filters.Better results were obtained by selcting proper interpolation functions comparing with that of tranditional GLM algorithm.And then optimization of CFBG was made by employing Genetic Algorithm (GA) to minimize the in-band group delay ripple(GDR) of CFBG,which verified the effectiveness of asymmetrical apodization scheme.4.Specific functional modules of all optical networks based on optical circuit switching were established and enhanced.The optimal scheme of burst contention was proposed Moreover combining with multicast technology,a novel scheme was investigated which was considered as the distributed and multi-link fault detections used in mesh and large scale optical networks.
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