Design And Applications Of The Ultra-high Speed All-optical Sampling System

The explosive bandwidth growth pushes the transmission speed of theoptical network stride to100G and even beyond. In ultra-high capacityoptical networks, it is mandatory to detect and localize signalimpairments which might deteriorate the data signal during transmissionin order to ensure the network reliability. Focused on optical dataquality monitoring in high bit-rate communication networks, this thesisis devoted to the development of an ultra-broad bandwidth sampling systemsimplemented by using the optical sampling technique. In this techniquethe signal under test is sampled by means of either a linear or nonlinearoptical process which delivers the ultra high sampling bandwidth requiredto observe such ultra-high speed signals.The research work are summarizedas follows:1. An optical-nonlinearity-based asynchronous optical under-samplingsystem using highly nonlinear fiber (HNLF) as sampling gate is introduced.Incorporated with a clock-recovery (CR) algorithm as the digital signalprocessor (DSP), such optical sampling system can be applied to theeyediagram measurement of the amplitude-shift keyed (ASK) signals. Underconsideration of the filter frequency response, an intuitiveunderstanding of the principle and an extensive analysis of the three keyparameters of the CR algorithm, namely the nonlinear function f(x), theblock size L and the filter length2K+1are presented.2. The eyediagram, bit pattern and relative clock wander monitoringof13.375Gb/s,26.5Gb/s,53.5Gb/s,107Gb/s RZ-OOK signals utilizing theoptical–nonlinearity-based asynchronous optical under-sampling systemis presented.A novel technique for clock-drift tolerant bit patternobservation and a robust solution for quantitative monitoring of therelative clock wander in the asynchronous under-sampling system aredemonstrated.3. An asynchronous optical linear under-sampling system based on quadrature optical hybrid (QOH) is built.Incorporated with the CRalgorithm plus the phase-estimation (PE) algorithm as the post-digitalsignal processor (DSP), such optical sampling system can be used for theeyediagram measurement of the ASK signals and most importantly for theconstellation diagram monitoring of the phase-shift keyed (PSK) signals.4. The eyediagram, bit pattern and relative clock wander monitoringof40Gb/s NRZ-OOK and160Gb/s RZ-OOK signals utilizing the asynchronousoptical linear under-sampling system is presented. Especially,themonitoring of the constellation diagrams of10Gb/s RZ-DPSK，80Gb/sRZ-DPSK，160Gb/s RZ-DPSK and40Gb/s NRZ-DPSK is also accomplished.