Research On All-optical Regeneration Technology Based On Magneto-optic And Four-wave Mixing Effects

All-optical signal regenerators can directly deal with the signals in optical domain,which overcomes the so-called electronic bottleneck involved in the conventionaloptical-electric-optical signal processing technology. By use of the intrinsicmagneto-optic (MO) effect in highly nonlinear fibers (HNLFs), the magneto-opticfour-wave mixing (MO-FWM)-based all-optial signal regeneration devices can beachieved with applications to intelligent optical networks. These devices aremagnetically controllable and their regeneration performance can also be improved bymeans of the MO effect.The main innovations are summarized as follows:1. The nonlinear propagation model of guided optical waves in MO fibers (that is,the MO nonlinear theory model) is proposed and the MO-FWM regenerationexperiment is carried out. Experimental results show that, when a170Gs direct-current(DC) magnetic field is applied along the HNLF, the regenerated signal power can beincreased and the receiver sensitivity is improved by1.2dB, which are in goodagreement with the theoretical results. For magneto-optic fiber Bragg gratings (MFBGs),the magnetic-field induced photonic bandgap shifting can also be explained by theabove-mentioned MO nonlinear theory. The Verdet constant of the Er-doped MO fiberis experimentally measured to be about-12.42rad/(T·m).2. The magnetic control characteristics of the MO-HNLF Sagnac interferometer areinvestigated in detail. Theoretical and experimental results show that:(1) themagnetically tunable dynamic range of the transmitted optical power is up to22dB forthe MO Sagnac interferometer;(2) in the MO nonlinear optical loop mirror(MO-NOLM), the transmitted idler power is proportional to the magnetic induction, andthe magnetic field sensitivity is263.93dB/T; and (3) for the MO-NOLM as regenerator,the magnetic field dependence of the power transfer function (PTF) is analyzed, and it isshown that the MO effect helps to reduce the nonlinear power threshold and increase thePTF slope. Based on the MO-HNLF Sagnac interferometer, the wavelength dependenceof the HNLF Verdet constant is obtained, and a temperature-insensitive magnetic fieldmeasurement scheme is also put forward.3. An idler-power-based feedback control scheme is propsed to stablize the fiber optical parametric oscillator (FOPO) for high-quality extracted clock signal with thetiming jitter of0.011UI. All-optical3R regeneration based on the single FOPO devicecan be realized by optimizing the pump power and the fiber polarization controllerwithin the fiber loop and the sensitivity improvement of3.42dB is obtained. Thus, thisfeedback control scheme is helpful for the commercial development of FOPOs.4. The all-optical3R regenerator, composed of the FOPO-based clock recoveryunit and the MO-NOLM reshaping unit, is experimentally studied. The timing jitter andamplitude noise of the signals can be further reduced and the receiver sensitivity isimproved by1.7dB under a200Gs DC magnetic field along the HNLF. In addition, thedata-pump and clock-pump FWM-based regenerators are comparatively investigated,which are applied to improving the extinction ratio and timing jitter of the degradedsignals, respectively.5. The offset filtering method is used to suppress the crosstalk in themulti-wavelength regeneration based on the bidirectional configuration, and all-opticalfour-wavelength2R regeneration based on the data-pump FWM effect in a single HNLFis achieved. The receiver sensitivities are respectively improved by2.05dB,2.53dB,3.57dB and2.8dB. The maximum extinction ratio improvement is about6.5dB.