Sohanpal, Ronit Singh;
(2024)
Optical frequency comb generation and applications in coherent optical communications.
Doctoral thesis (Ph.D), UCL (University College London).
Preview |
Text
PhD_Thesis_Accepted.pdf - Accepted Version Download (13MB) | Preview |
Abstract
Optical frequency combs (OFCs) are a multi-wavelength source consisting of a series of sharp discrete spectral tones exhibiting broadband frequency coherence. Over the past decade, frequency combs have enabled significant developments in the fields of metrology, spectroscopy, microwave photonics and optical communications. Coherent communications in particular has seen significant interest in leveraging the coherence of OFCs to enable low-complexity and high-performance DSP. However, many existing comb generation techniques possess sub-optimal properties for coherent WDM systems with respect to their power-per-tone, optical signal to noise ratio (OSNR), spectral flatness and bandwidth. In addition, many applications of OFC frequency coherence have yet to be explored, particularly the potential benefits and limitations of OFCs for transmitter-side nonlinearity mitigation. There are two main focal points of this thesis. The first focus is on the generation of optical frequency combs specifically designed for the requirements of coherent WDM communications systems, with an emphasis on the optical fibre platform, high optical power-per-tone, high OSNR, flatness and broad bandwidths. To this end, an electro-optic-modulator-based comb generator was designed, numerically modelled and experimentally tested to generate an optical frequency comb spanning the C-band using tailored optical pulse shaping and fibre-based nonlinear mixers. In addition, a novel nonlinear fibre waveguide called silicon core fibre was modelled, tested and evaluated as an ultra-short nonlinear mixer for compact fibre comb generation architectures. The second focal point of this thesis is on the application of frequency combs in coherent communication systems. The efficacy of frequency comb sources for fibre nonlinearity mitigation was investigated numerically in the presence of various frequency noise impairments such as laser phase noise and frequency dither. A coherent recirculating loop testbed was used to experimentally investigate comb-based nonlinearity mitigation in various transmission scenarios.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Optical frequency comb generation and applications in coherent optical communications |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10194716 |
Archive Staff Only
 |
View Item |
