Investigation Of High-Speed All-Optical Digital Logic Operation Using Logic Minterm

All-optical switching will play important role in next generation optical network withincreasing single channel bit-rate and transmission channels, because the optical-electrical-optical (O-E-O) conversion can be avoided. All-optical signal processing is one of the mostimportant enabling technologies for all-optical switching, where all-optical logic operationsplay an essential role in optical switching node, and some important node functions shouldrely on all-optical logic operation techniques, such as header recognition, header/payloadseparation, payload routing, header conversion, and so on.Among the optoelectronic and photonic devices used for all-optical signal processing,semiconductor optical amplifier (SOA) is one of the most competitive candidates because ofits high nonlinearities, low power consumption, high conversion efficiency, high reliability,as well as easy integration with other optoelectronic and photonic devices. In thisdissertation, many kinds of all-optical logic building blocks have been experimentallydemonstrated at40Gbit/s which are suitable for differential phase shift keying (DPSK) andon-off keying (OOK) signals based on SOAs. The major research achievements andcontributions of the dissertation are summarized as follows:At first, all-optical logic functions based on delay interferometer (DI) and SOA aretheoretically investigated. The transmission matrix and transmission function of the DI arederived. The DI-based differential demodulation process of DPSK signal with generation oftrue form and complemenary data pattern, and the impact on the demodulated signalsinduced by the offset between the carrier wavelength and the transmission spectrum of theDI are analyzed with numerical simulation. In the proposed reconfigurable all-optical logicoperation scheme for DPSK signals, the influences of the power of the input data signal, thebandwidth of optical filter, and filter detuning on the performances of output logic signalsare analyzed theoretically.Secondly, All-optical multi-input reconfigurable all-optical logic minterm and maxtermgenerations, as well as the relation between their performances and working conditions areexperimentally studied using the proposed reconfigurable all-optical logic operation schemefor DPSK signals. Reconfigurable all-optical two-input logic maxterm is successfullygenerated by coupling the obtained all-optical logic minterm and the pump data signal. Considering the complementary properties between the minterm and maxterm and NOTlogic functionality based on the cross-gain modulation (XGM) in SOA, the correspondingthree-and four-input maxterm is further generated from the derived logic minterm. Theexperimental results show that all the output logic signals exhibit good quality, which areexpected to be further used to construct arbitrary logic operation.Thirdly, All-optical combinational logic units for DPSK signals are proposed andexperimentally demonstrated using the proposed scheme for DPSK signals. Thesecombinational logic units include1-to-2and1-to-4data distributor,2-to-1data selector,Simultaneous digital comparator and dual-directional half subtractor, full set of two-inputlogic gates, reconfigurable and scalable logic building block. The experimental results showthat these combinational logic units for DPSK signals exhibit good output performances,which may be widely used in the high speed all-optical digital signal processing system andphotonic computer in the future.At last, All-optical combinational logic units for OOK signals are designed andexperimentally studied using four wave mixing (FWM) and XGM effects in SOAs. Thesecombinational logic units include1-to-2data distributor,2-to-1data selector,3-input and4-input digital priority encoder. The experimental results show that these combinational logicunits for OOK signals exhibit good output performances, and potential applications forfuture high speed all-optical digital signal processing systems and all-optical computingsystems.