All-optical Signal Transformation:Theory And Applications

All-optical signal processing has been the key technique to realize the ultra high-speed and large capacity all-optical telecommunication network in the future, since it can break the speed limit of traditional optical-electric-optical conversion process. All-optical transformation is one of the most important parts in all-optical signal processing, and is to manipulate the signal itself in time or spectral domain. This dissertation centers on the theory and application of all-optical signal transformation, and investigates on the aspects of theoretical analysis model of linear optical signal transformation based on optical filter, signal transformation based on space-time duality and optical performance monitoring. Research achievements and contributions are summarized as following:(1) The basic theory of linear signal transformation is investigated. The characteristic relationship between the field and spectrum of the signal is theoretically analyzed. Then a complete theoretical model and analysis are proposed, it is used to analyze the all-optical linear signal transformation, including the analog spectrum transformation and digital spectrum transformation. Afterwards, the operation principle of signal demodulation is presented. At last, the basic principle of signal transformation based on space-time duality is provided.(2) Several temporal imaging and temporal Fourier transformation techniques are achieved based on space-time duality. Analog to the spatial imaging system, the temporal imaging system using temporal pinhole, temporal eye, temporal Fresnel zone plate are investigated, and then these imaging systems are compared and analyzed. Analog to the spatial convex-lens based focus system, a reconfigurable temporal Fourier transformation and temporal imaging system is presented and demonstrated. This system is further extended to the investigation of temporal concave-lens based scatter system for waveform stretch. Finally, an equivalence relationship between "dispersion+time lens+dispersion" structure and "time lens+dispersion+time lens" structure are investigated, and it is used to simplify the cascaded multi time lens system.(3) Complex signal transformation functionalities are achieved by combing the temporal simplified4-f system and nonlinear signal transform techniques. By implementing the field square, field multiply and conjugated multiply operation at the focal plane of the temporal simplified4-f system, the self-convolution, convolution and correlation manipulations are realized. Thus based on the self-convolution system, the triangular shaped pulse and tunable triangular shaped pulse are obtained from rectangular shaped pulse. Then based on the convolution system, the trapezoid shaped pulse and tunable trapezoid shaped pulse are acquired from rectangular shaped pulses. Moreover, the general convolution system and correlation system are realized, the algorithm transfer functionality is achieved by using the convolution system while the packet recognition functionality is realized by utilizing the correlation system.(4) The temporal imaging system and temporal Fourier transformation system for incoherent signal are investigated. Firstly, the basic principle of incoherent signal transformation based on space-time duality is provided. For temporal imaging, the temporal imaging system using time lens, temporal pinhole, temporal eye and temporal Fresnel zone plate are investigated. Meanwhile, the reconfigurable temporal imaging system using temporal convex-lens and concave-lens are also investigated. For temporal Fourier transformation, the Fourier transform operation are investigated. Meanwhile, several Fourier transform system for incoherent signal are analyzed.(5) Optical performance monitoring. Monitor the dispersion of modulated signal in time domain, frequency domain and radio frequency domain, respectively. In the time domain, the dispersion is monitored for NRZ-DPSK signal by using the asynchronous histogram evaluation method and curve fitting arithmetic. In the spectral domain, the dispersion is monitored for RZ-OOK signal using the autocorrelation trace of the signal’s sideband. In the radio frequency domain, the dispersion is monitored by the character of the RF spectrum of (N)RZ-DPSK signal combined with the RF transfer technique using the nonlinear effect of SOA.