Study On Optical Pulse Generation And Frame Clock Extraction Techniques From160Gbit/s OTDM Signal

High speed optical time-division multiplexing (OTDM) system is quiteattractive in both theoretic studies and practical applications due to itscharacteristics of effectively increasing transmission capacity in futurebackbone communication networks. Ultra-short pulse generation and frameclock extraction are two key techniques in such systems. In this dissertation,we present a pulse generator using commercial cascaded lithium niobate(LiNbO3) modulators and a clock extraction unit using single-loopoptoelectronic oscillator (OEO). The operation principles and correspondingexperimental results are discussed for further analysis.The scheme using commercial cascaded LiNbO3phase-intensitymodulators to generate optical pulse is theoretically studied. The simulationresults show the impact on pulse compression property with variable inputpulse width and optical power, and pulse evolution processes in differentstages are also compared by numerical method. In the experiment, thegenerated initial pulses are further compressed and the remaining pedestalsare eliminated.1.4ps pedestal-free10GHz pulse train is successfully obtained,and the corresponding timing jitter is calculated to be132fs. The pulse sourceis applied in10GHz-160Gbit/s OTDM test and the results confirm its quality.The principles of free running、injection locking and harmonic sidebandmixing occurred in the OEO loop are discussed in detail. The experimentssuccessfully obtain10GHz frame clocks from4×10Gbit/s OTDM signal beforeand after40km transmission and16×10Gbit/s OTDM high-speed signalrespectively with the condition of injection locking. The corresponding timing jittersare measured to be129fs，151fs and136fs. Harmonic sideband mixing effects inOEO are applied in optical all-one coded signal modulated by10GHz×4frequency multiplication clock and by pure40GHz clock respectively to obtain1/4fractional frequency clock, with corresponding measured timing jitters to be only 133fs and69fs. The results testify the fractional clock extraction functionality can berealized in the OEO.