Study On All-Optical Key Techniques In High Speed Communication

As user demand has expanded dramatically and developed quickly with multi-media features as well as the rapid growth of internet traffic, they have put forward higher requirements for optical communication capacity and optical-layer function, which prompt researchers to seek technical breakthrough. According to all-optical key techniques of high speed optical communication, supported by National key basic research development program (973Program)"Research on theory and key techniques of optical devices towards optical circuit switching network", National High Technology Research and Development Program (863Program)"Study on160Gb/s OTDM transmission system using multi-fiber pump", Key Program of National Natural Science Foundation "Key techniques research on all-optical circuit switching network", this thesis is devoted to deep investigation into the theoretical and experimental research on optical time division multiplexing (OTDM) and demultiplexing techniques, OTDM transmission link dispersion management, all-optical clock extraction technique, optical delay technique, and all-optical switching. The main innovative research efforts are summarized as follows:1. Picosecond pulses were experimental generated employing self-made dispersion decreasing fiber and dispersion shifted fiber, phase modulation was introduced to suppress the harmful effect of stimulated Brillouin scattering, the power injected to fiber was increased by about10dB.160Gb/s multiplexed signal was generated using optical time division multiplexer. Symmetric strong dispersion map was adopted for100km transmissions, which could precisely compensate the dispersion and its slope, meanwhile, the intra-channel nonlinear effects were suppressed. A novel feedback loop based on cascaded electro-absorption modulators and clock recovery module was proposed for achieving clock enhancement and subsequently recovery and demultiplexing simultaneously. Error free160Gb/s OTDM100km transmission was realized, which keep for over two hours. A scheme for increasing spectrum efficiency of OTDM signal by designing a matching filter of demultiplexing switching window was proposed, the related experimental results show that spectrum efficiency was unproved by three times comparing with original40Gb/s OTDM singals.2. All-optical clock extraction based on stimulated Brillouin scattering (SBS) was deeply researched. Its structure parameters were optimized based on numerical model. Clock components enhancement induced by nonuniform multiplexed signal and unequal-amplitude were theoretically analyzed, frame clock and bit clock extraction schemes were proposed and the former one was implemented successfully. Clock extraction from multiwavelength Return-to-Zero signals was realized, and maximum frequency spacing for dual-wave length all-optical cbck extraction based on SBS was analyzed and demonstrated experimentally, which also present an idea for the measurement of SBS gain bandwidth. An optimized scheme of all-optical clock enhancement based on semiconductor optical amplifier and chirped fiber Bragg grating (CFBG) was presented, and a numerical model of the clock enhancement structure was established, the related parameters were optimized in simulatioa The tolerance for input degraded signal was analyzed, and clock enhancement and extraction from NRZ signals through different length transmission and multiwave length NRZ signals were realized experimentally.3. Integrated waveguide delay line based on micro-ring resonator was designed. Delay characteristics infulenced by total number of micro-rings and micro-ring resonant frequency deviation were deeply studied. An efficient thermo optic detuning scheme was applied to improve the delay bandwidth while ensuring the maximum delay. The fabrication, assembly and test are implemented. A delay line with continuously adjustment from213ps to Ops was demonstrated, and the different delay of multi-branch with continuous adjustment and high precision could be realized simultaneously.4. An optimized Drop-and-Continue structure based on CFBG was proposed for the realization of optical cross connect function of optical-layer multicast. The robust, configurable, effective, real-time, high quality video and data multicast service were realized experimentally. Distributed network management scheme was studied, and specific functional modules of a novel all-optical network based on optical circuit switching were established and enhanced.