Crosstalk cancellation in WDM optical interconnects.
Doctoral thesis, UCL (University College London).
The aim of this project is to investigate the use of high speed digital signal processing (DSP) to improve the performance of low cost, low power wavelength division multiplexed (WDM) optical interconnects. Optical technology offers the multi-Gbit/s transmission capacities that will be required to connect processors in data centres and high performance computers. However, physical effects limit the achievable optical link capacities that can be achieved, one major problem being the crosstalk due to interference between WDM channels which imposes a lower limit on the channel spacing. A method of canceling this crosstalk would have a major impact on the performance of such systems. This thesis begins with an introduction to crosstalk and the theory describing it. Results on crosstalk cancellation previously reported in the literature are analysed. Following this, the DSP-based multiple-input and multiple-output (MIMO) crosstalk cancellation approach proposed in this project is presented, and initial circuit designs and simulation results are presented. The effectiveness of both transmitter- and receiver-based MIMO crosstalk cancellation were assessed for two and three channel WDM systems through simulations. Next a two channel transmitter with crosstalk cancellation, based on Tektronix 12 GS/s arbitrary waveform generators (AWGs) was demonstrated. The DSP for these experiments were carried out offline, using Matlab. A reprogrammable field-programmable gate array (FPGA)-based 10.7 Gb/s optical transmitter incorporating crosstalk cancellation for one and two interfering channels using real-time DSP was then developed and tested through simulations and experiments. Finally, combined transmitter and receiver MIMO processing for crosstalk cancellation was investigated experimentally using off-line DSP, 12 GS/s AWGs and a 50 GS/s real-time oscilloscope.
|Title:||Crosstalk cancellation in WDM optical interconnects|
|Additional information:||Permission for digitisation not received|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Engineering Science
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