Thiele, Hans Joerg; (2000) Investigation of high-speed optical fibre transmission in the presence of fibre nonlinearities. Doctoral thesis (Ph.D.), University College London (United Kingdom).

Text Investigation_of_high-speed_op.pdf Download (12MB)

Abstract

This thesis investigates the impact of nonhnear effects on optical transmission in wavelength-multiplexed (WDM) and optical time-domain multiplexed (OTDM) systems up to 40Gbit/s. The degradation due to cross-phase modulation (XPM) in multi-channel WDM systems is analysed and the increase of error-free transmission distance is shown for optically regenerated OTDM systems. The high powers needed to maximise inter-amplifier span lengths in high bit-rate multi-channel WDM transmission systems result in increased signal distortion and bit error-rate due to fibre nonlinearities. One of the dominant multiwavelength nonlmearities is XPM causing a variation of the optical phase due to power fluctuation in the other channels. This phase fluctuation is subsequently converted into amplitude distortion by the residual system dispersion leading to eye closure. This thesis focuses on the investigation of XPM distortion as a function of fundamental systems parameters using a straight line and recirculating loop fibre transmission system. A technique is proposed to minimise the residual dispersion of the fibre links by adding lumped dispersion at the receiver, efficiently reducing the impact of XPM on multi-channel transmission. Another important aspect addressed in this thesis is the validation of the laboratory measurements: the simplicity of the pump-probe configuration allows the comparison with analytical calculations. The first field experiment investigating XPM distortion of the installed fibre in the BT LEANET network between Ipswich and Norwich, UK is described. The impact of XPM on transmission is assessed in additional Q-factor measurements and compared to the pump-probe measurements of signal distortion. A technique is proposed to accurately estimate XPM penalty in WDM optical fibre transmission experiments. In the second part of the thesis, an application of fibre nonlinearities is shown for a single channel OTDM transmission at 40Gbit/s. Self-phase modulation (SPM) can compensate the dispersive broadening of the RZ pulses and thus increasing the error-free transmission distance. An all-optical semiconductor-based regenerator using a unidirectional nonlinear interferometer (UNI) configuration is described and its capability to operate at 40Gbit/s is demonstrated. A recirculating loop is used to operate this regenerator in a multi-span link and cascading of the regenerator up to 20 times effectively increases the error-free transmission distance.

Download activity - last month

Export as CSVJSONXML

Download activity - last 12 months

Export as CSVJSONXML

Downloads by country - last 12 months

Export as XMLJSONCSV

Archive Staff Only

View Item