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Research Of Novel Optical Labeled Switching Systems And Optically Controlled Optical Switching Components

Posted on:2011-09-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y S CaoFull Text:PDF
GTID:1118360308461151Subject:Optical Engineering
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Optical communication has become the one of the most important parts in modern communications, due to the explosive growth of Internet data and services,and its developing direction is all-optical network (AOS),with high-capacity and broad bandwidth. Recently, the transmitted data rate in backbone has reached Tb/s level, due to the wide application of dense wavelength division multiplexing (DWDM) technique.However, as an indispensable part in optical communication network, the switching node still needs optical/electronic/optical (O/E/O) transformation,and the packets need to be processed in electrical domain, which limits the transmission rate of the current communication networks and causes the "electronic bottleneck" on data processing and transmission, due to the limitations by the speed of electronic switching and electrical information processing.To resolve this problem, optical labeled switching (OLS) technique was proposed.OLS provides a mixed optoelectronic structure, and it has become the developing direction of next generation optical transport network (OTN) and optical switching network (OSN).The operation principles of two of the most promising optical labeled techniques---orthogonal modulated optical labeled technique and optical code (OC) labeled technique are theoretically studied, and the parameters setting and transmission characteristics analysis and comparison of these two techniques are investigated by simulation;furthermore, the operation principles and optimizing schemes of a novel optically controlled optical switching device based on self electro-optic effect (SEE)---self electro-optic effect device (SEED) are investigated by theoretic analysis and simulation.The contents include:1.Study on orthogonal modulated optical labeled techniqueBuilding the simulation setup of 40 Gb/s, ASK/FSK orthogonal modulated OLS system:1)the structure, operation principles and transmission performances of orthogonal modulated OLS system are studied; 2) to improve system transmission performance, some parameters, such as extinction ratio (ER),dispersion compensation scheme and label frequency spacing, are optimized;3) a novel method on FSK signal spectrum equalization by using an optical band-pass filter (OBPF) is proposed.According to the simulation results,the ASK payload signal quality can be improved by using this equalization method; 4) at the core node of network, a scenario on FSK optical label erasing and inserting by using SOA-MZI structure is proposed.Simulation results indicate that, by using this scheme, FSK label can be removed and inserted in optical domain, with low power penalty; 5) two advanced modulation formats---DPSK and DQPSK formats are introduced, and by combining four different modulation formats---FSK, ASK, DPSK and DQPSK, five orthogonal modulated optical labeled systems---DPSK/FSK, DPSK/ASK, ASK/DPSK, DQPSK/FSK and DQPSK/ASK systems, with 40 Gb/s payload signals, are proposed.Analysis on system performances and optimization on system parameters are accomplished by using simulation setup, and the system transmission performances and anti-noise performances of different modulation formats and code types are also investigated.The results revealed that at RZ-DQPSK/ASK system could reach a highest label bit rate,a best received sensitivity and an optimal transmission performance.2.Study on coherent detected spectral amplitude code (SAC) labeled switching systemBuilding the simulation setup of 40 Gb/s,SAC labeled switching system:1) by using optical coherent detection, some creative improvements and innovations on current SAC label recognition unit are achieved:a linear time-to-frequency swept local oscillator(LO)with a constant emission power is constructed.156 Mb/s,4-wavelength SAC labels could be detected by the LO, and recognized by balanced detection. This novel method significantly simplifies the conventional SAC label recognizing unit, reduces the cost and avoids the large optical splitting loss;2) based on the coherent detected label recognizing unit, SAC labeled system performances with 40 Gb/s, IM, DPSK and DQPSK payload signals are compared by simulation. The results reveal that DQPSK payload has the best transmission characteristic; 3) SAC labeled 112 Gb/s, multi-channel and multi-bit rate DQPSK system is proposed and demonstrated; 4) a novel SAC label encoder is proposed.It consists of pseudo-random binary sequence (PRBS) generators and 1x2 optical switches,and based on this encoder, the BER performance of SAC labels is estimated for the first time;5)based on coherent detection, SAC implicit labeled system is proposed,625 Mb/s and 1.25 Gb/s systems are demonstrated.The results imply that, in this system, payload bit rate can't exceed 1.25 Gb/s, otherwise, frequency swept LO can't detect the correct label signal;6) a novel method on generation of multi-frequency SAC labels,by using a Fabry-Perot (F-P) tunable filter and a frequency-swept laser, is proposed.The conventional system complexity and cost could be reduced by using this method, due to the number of lasers in label generator is decreased. SAC labels up to 16 frequencies could be generated by one laser, and the label bit rate can be accelerated to 1.25 Gb/s;7) based on label stacking principles and coherent detection, multi-label SAC switching system is proposed.By using continous frequency swept LO, systems with 40 Gb/s various payloads and 256 labels are demonstrated by simulation.The results indicate that label quality goes worse very quickly, when the number of labels from 2 to 64; however, label quality only has a slight change, when the number of labels from 64 to 256.That means multi-label system can be achieved by using label stacking; 8) by using label stacking principles, two-hop, coherent detected SAC labeled system is proposed.Label switching node, label processing unit and electrically controlled 1√óN optical switches array are established. Therefore, a SAC labeled network with two-hop switching, forwarding and transmission is achieved.3.Study on a novel optically controlled optical switching component---self electro-optic effect device (SEED)Based on the analysis on quantum confined Stark effect (QCSE) and the operation principles of SEED, and by using an equivalent resistance-capacity (RC) model,voltage diffusion expressions and Kirchoof laws:1)theoretical analysis on SEED optically controlled optical switches,symmetrical-SEED (S-SEED) optically controlled optical switches and S-SEED optically controlled optical buffers is completed, and the approximate expressions, which reflect the relationship between the switch time and voltage of these three components are obtained; 2) some parameters of these components, such as input optical power, input optical wavelength and input power ratio are optimized, and some effective methods on enhancing the performances of the components are found by simulation analysis;3) exploration on an optical labeled switching system, which is based on SEEDs was studied. Attempting to applying SEED optically controlled optical switches, logic gates and buffers to the core node of the labeled switching system, and expecting the all optical label processing and switching can be achieved.
Keywords/Search Tags:optical label switching (OLS), orthogonal modulated optical label, optical code (OC) label, spectral amplitude code (SAC), coherent detection, optically controlled optical switching components
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