| As the bearer of upper network services,optical fiber communication networks must constantly improve network capacity and architecture to cope with the growing bandwidth requirements and the various types of services.The improvement of network capacity mainly depends on higher signal baud rate,higher order modulation formats and more complex multiplexing methods.The increase of upper services also drive the evolution of optical network from a simple information transmission channel to a multi-functional and multi-level flexible optical network.Facing the change of network characteristics,traditional optical-electrical-optical(OEO)conversion-based signal processing technologies gradually present some serious problems such as the electronic bottleneck,low conversion efficiency,high costs and so on.All-optical signal processing is always the frontier and focus of the optical communication researches which mainly employs nonlinear optics to realize the flexible controlling and processing for the optical signals in all-optical domain and can avoid the issues caused by the OEO conversion.The large capacity high-order optical vector signals with various multiplexing technologies will be adopted by the future optical networks,how to realize the all-optical processing for these optical vector signals is the key issue of the all-optical signal processing researches.Phase-sensitive amplifier(PSA)provides possible solution for this issue because of its specific phase-sensitive characteristic,the PSA-based all-optical vector signal processing technologies also have been the hot issue for the optical communication domain.The PSA-based signal processing has extensive application prospect and a lot of signal processing technologies have been proposed by the researchers around the world such as vector signal regeneration,format conversion,low-noise amplification,all-optical phase quantizing and optical vector quadrature de-multiplexing.This dissertation focuses on the key technologies and issues of the PSA-based all-optical vector signal processing,the main achievements and innovations are as following:Firstly,a PSA-based format conversion scheme is proposed and verified by simulations which implements the conversion from one QPSK signal into one BPSK signal with information-integrity.For the input QPSK signal with OSNR of 15 dB,when the BER is 10-3,the receiver OSNR of the converted BPSK is improved by 3.2 dB compared with the original QPSK signal.The system will be of great necessity for the scenarios such as the rapidly deteriorated optical links environment,the nodes between different networks and software-defined transceivers.Secondly,a PSA-based reconfigurable optical network intermediate node system with capacities of full-quadrature regeneration and format conversion is proposed.For an input noisy QPSK signal,the node can choose to output a QPSK signal or a converted PAM4 signal,both are full-quadrature regenerated.For input QPSK signal with OSNR of 15 dB,when BER is 10-3,compared with input QPSK signal,the receiver OSNR of regenerated QPSK signal improves by 2 dB,and the receiver OSNR of converted PAM4 signals improves by 1.3 dB.The node system can be employed by the node between long-haul transmission optical networks or the node between the networks which employ QPSK and PAM4,respectively.Thirdly,the optical vector quadrature de-multiplexers(QDs)are proposed and verified within the medium of HNLF and SOA.The QD is based on a single bi-directional PSA and can simultaneously extract the in-phase and quadrature components of input optical vector signals,meanwhile,the wavelengths and polarization status of the extracted components are the same with the input vector.The QAM signals are transmitted through the node to test the quadrature de-multiplexing function and 16/32/64 QAM signals are de-multiplexed into two PAM4/PAM6/PAM8 streams.The proposed QD scheme can be employed as the basic function unit for flexible controlling and processing optical vector signals in future optical networks. |
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