Optimization of a vestigial side-band transmitter.
|Student Report - Shuyuan Qin - May 2007 |
Student report, COM-DTU, Department of Communications, Optics and Materials, Technical University of Denmark, Kgs. Lyngby, Denmark. Supervisors: Christophe Peucheret
In order to build future flexible and cost-effective DWDM systems, advanced modulation formats with high spectral efficiency and dispersion tolerance are needed. We use the commercial simulation software VPITransmissionMaker to carry out the project. We have shown how to generate various intensity modulation formats based upon Mach-Zehnder modulator, including non return-to-zero (NRZ), return-to-zero (RZ) with 50%, 33% and 67% duty cycle, Duobinary NRZ (DBNRZ) and Alternate-mark inversion (AMI) modulation formats. For the purpose of enhancing the spectral efficiency of optical signals, we try to adopt vestigial sideband (VSB) filtering at the transmitter side. Gaussian bandpass filters with 1st and 2nd order are used as the VSB filter. For some convenience, we have assumed no fiber loss and nonlinearity. Simulation results showed that RZ signals benefit the most from VSB filtering due to their high spectral width. When the extinction ratio is very high, Duobinary NRZ gives an excellent performance transmitted in the fiber, especially the one generated by severe electrical low-pass filtering.
Shuyuan_Qin_Special_Course_VSB.pdf (only available from COM•DTU)
Record created 2007-07-04, last modified 2008-10-15
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