Flexible Transparent Optical Network Adaptive Transmission Mechanism And Key Technology Research

Agile and transparent optical network is the important evolution direction of optical transport network and the agility and transparency are convenient to operate and manage the network. For example, the distributed intelligent control plane can be constructed by generalized multi-protocol label switching (GMPLS), and the fast connection setup and remove can be realized. Then this can support dynamic service configuration and efficient resource optimization. Moreover, all kinks of transparent optical components, such as photonic cross connector and tunable all-optical wavelength converter, have been commercialized. This can support all-optical signal transmission and reduce the quantity of expensive optical-electrical-optical conversion devices and decrease CAPEX and OPEX.However, the agility and transparency also bring some problems because the physical impairments will be cumulated without optical 3R regeneration. The network agility will be enhanced as the topology evolves to mesh, and the lightpath change will result in dynamic change of the cumulative physical impairments. Then this may cause the signal degradation or even transmission requirements cannot be satisfied. Although some adaptive impairment compensators have been developed to resolve this problem, these components only realize local adaptive adjustment. They cannot understand the compensation states of each other and lack the team-working ability. Then this would result in unnecessary overhead. Therefore the above problems are investigated in depth with the support of the Hi-Tech Research and Development Program of China, and the research results have or will be published in Optics Express and Journal of Optical Networking. The main innovative results are listed as follows.Firstly, for the sake of solving the above problems and making the best of the compensation capability of various tunable devices, we proposed the thought of adaptive transmission in agile and transparent optical networks for the first time, which can support dynamic end-to-end optimization for quality of transmission. The global transmission quality from source to destination can be adjusted and improved dynamically through adding the capacity of controlling physical characteristics of transport plane into ASON.Secondly, based on the current control plane in ASON, we designed the architecture of adaptive control plane which can support adaptive transmission. And the new four function modules, namely information collection module, performance estimation module, compensation budget computing module, and performance control module, had been added. Then the dynamic end-to-end adjustment can be achieved and the system overhead will be decreased.Thirdly, we proposed the preliminary solutions to the key problems caused by adaptive transmission which mainly included 1) the extension of GMPLS signaling protocol to support the collection of physical parameters and the delivery of optimization parameters; 2) the fast estimation methods of transmission performance including the residual path dispersion, the received OSNR and the cumulative nonlinear phase shift; 3) the optimization model creation and the feasible heuristic algorithms design.Finally, based on the physical model of optical pulses propagation in photonic crystal fibers (PCFs), we had independently developed the computer program which can simulate the process of ultra-short pulses propagation in PCFs. Based on this tool, the effect of initial frequency chirp on supercontinuum generation (SCG) is investigated numerically in PCFs with two zero-dispersion wavelengths for the first time. The positive chirps, instead of zero or negative chirps, are recommended because self phase modulation and four-wave mixing can be facilitated by employing positive chirps. In contrast with the complicated and irregular spectrum generated by negative-chirped pulse, the spectrums generated by positive-chirped pulses are wider and much more regular. Moreover, the efficiency of frequency conversion is also improved because of initial positive chirps. Nearly all the energy between the zero-dispersion wavelengths can be transferred to the normal dispersion region provided that the initial positive chirp is large enough. This property has important potential applications in tunable all optical wavelength conversion and broadband parametric amplification.