Parallel Processing Method In Optical Analog To Digital Conversion And SOA Based Packet Switching

Optical analog-to-digital conversion and all-optical packet switching technologyare playing important roles in many areas.A four-wave-maxing-based parallelization scheme for processing high speed op-tical samplers is proposed in this thesis. By using this scheme, samplers at the samewavelength can be converted to multi-wavelength ones and then parallelized usingwavelength division demultiplexing method. Under the sampling rate of9.95GHz,parallelization of six channels is obtained and the measured crosstalk from adjacentchannels higher order four-wave-maxing components are less than-29dB, and OSNRof the six channels are between29.3dB and36.8dB. Comparison between the phasenoise spectrum before and after the parallelization demonstrates that timing jitter isnot increased and the phase noise with low frequency is suppressed. Ten parallelizedchannels are also obtained under the same sampling rate. Cross talk from the adjacentchannels and higher order four-wave-mixing components are less than-29.6dB. Theparallelized samplers are also digitized by using an electrical ADC when a RF signalof4.4GHz is applied, the calculated SNR of the channels are from24.9dB to27.3dB, which is equal to the SNR before parallelization. Key factors which afect theperformance of system are also discussed in this thesis.In order to get sampling source at a higher repetition rate to sample RF signalwith broader bandwidth, we compress an optical pulse train of10GHz repetition rateby nonlinear compression method. When using single mode fiber for compression,the shortest pulse obtained has FWHM of0.457ps. When single mode fiber is sub-stituted with a2m long dispersion compensating fiber to compensate the additionalabnormal dispersion introduced by the devices that followed, the shortest pulse ob-tained has FWHM of0.318ps, corresponding to the compression factor of16.4. Bymultiplexing, the repetition rate of the short pulse train is converted to640GHz, andthe autocorrelation trace of it demonstrates that the pulses are well equalized. Based on the nonlinear polarization rotation efect in SOA, a scheme of opticalcontrolled2×2cross/bar optical packet switch is proposed. This scheme has the ad-vantages of low cost, high speed, being transparent to the format and wavelength ofdata and low power cost. The function of switch is demonstrated when the input data is10Gbit/s. The switching energy per bit is400fJ and the switching time is measured tobe less than1ns. When the input data rate is10Gbit/s, bit-error-rate measurements arecarried out under diferent occasions of inputs and state of the switch, and the powerpenalties are obtained. Under a bit-error-rate of10-9, when data is presented in onlyone of the inputs, the highest power penalty of the switch is1.8dB. When data is pre-sented in both of the inputs, the highest power penalty of the switch is2.3dB. Backreflection of SOA and extinction ratio of polarization beam splitter, which afects theperformance of the switch, are also discussed. Based on the all optical2×2packetswitch, an optical control unit which can be used in all optical stack bufer is proposed.