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Abstract
We present a modelling technique and noise analysis of a clock recovery scheme based on an optoelectronic phaselocked loop. We treat the prob
lem using techniques from stochastic processes and stochastic differential
equations. A set of stochastic differential (Langevin) equations describing
the optoelectronic phaselocked loop are derived. By using smallsignal analysis, the Langevin equations are linearized and the associated system of stochastic differential equations is solved using Fourier techniques. Nu merical simulations are then used to investigate the performance of the optoelectronic phaselocked loop with noise at a bitrate of 160 Gb/s. It has been shown that it is important to reduce the time delay in the loop since it results in the increased timing jitter of the recovered clock signal. We also investigate the requirement for the freerunning timing jitter of the local electrical and optical oscillator. We show that it is possible to obtain recovered clock signal with less timing jitter then the input data signal as long as the jitter of the freerunning electrical oscillator is less than the input data signal timing jitter. Using the guidelines form the nu merical simulations, optoelectronic phaselocked loop based clock recovery operating at 320 Gb/s is demonstrated. Optical regenerator with clock recovery, based on an optoelectronic phase locked loop, is also described using techniques from stochastic calculus. An analytical expression for the power spectral density of the retimed data sig nal is derived. We use numerical simulation to investigate the performance of the optical regenerator operating at 40 Gb/s and 160 Gb/s. We have shown that for flattop input data signal pulses and sufficiently narrow op tical clock signal pulses, the timing jitter of the retimed data optical data signal can be significantly reduced compared to the jitter of the degraded input data signal. The optical clock signal pulse width needs to be rela tively short compared to the optical data signal pulse width in order for the retimed data signal timing jitter to coincide with the recovered clocktiming jitter, i.e. 3.5 ps at 40 Gb/s and 0.5 ps at 160 Gb/s. In the last part of the thesis, a novel phaselocked coherent optical phase demodulator with feedback and sampling, to be used in phasemodulated radiooverfibre optical links, is also presented, theoretically investigated and experimentally demonstrated. It is experimentally shown that the proposed approach results in 18 dB of spurfreedynamic range improve ment compared to a traditional demodulator without feedback. A new timedomain, large signal, numerical model of the phase locked coherent demodulator is developed and shown to be in excellent agreement with ex perimental results. Numerical simulations are used to investigate how loop gain, LO phasemodulator nonlinearities, amplitude modulation, ampli tude and timing jitter influence the dynamical behavior of the demodulator in terms of the signaltointermodulation ratio and signal tonoise ratio of the demodulated signal. Furthermore, in order to alleviate nonlinearities associated with the LO phasemodulator, we report on a novel technique for cancelation of the 3rd order intermodulation product of the demodulated signal. The proposed cancelation technique does not depend on input RF signal power and frequency.
Original language  English 

Number of pages  164 

ISBN (Print)  8792062075 
Publication status  Published  Sep 2007 
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Projects
 1 Finished

Low Power Adaptive Beamforming
Zibar, D., Jeppesen, P., Clausen, A., Mork, J., Oxenlowe, L. K., Christensen, E. L., Petermann, K. & Jacobsen, G.
01/05/2004 → 28/09/2007
Project: PhD