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UID:20260523T173932EDT-5309kM8eFl@132.216.98.100
DTSTAMP:20260523T213932Z
DESCRIPTION:Abstract\n\nIn recent years\, silicon photonics has emerged as 
 a promising technology for optical communication systems. The integration 
 of silicon photonics with other materials and technologies has opened up n
 ew avenues for developing high-performance and cost-effective optical comm
 unication systems. This has led to significant research and development ef
 forts in the field\, intending to achieve better performance\, higher inte
 gration\, and lower power consumption. In this thesis\, we aim to address 
 an intriguing question - what would coherent transceivers look like in the
  future to serve high-capacity wavelength division multiplexing (WDM) syst
 ems?\n\nIn the first part of the thesis\, we propose a wavelength-selectiv
 e filter based on waveguide Bragg gratings on the Silicon-on-insulator (SO
 I) platform. The proposed device not only provides control of the resonanc
 e wavelength but can also provide multi-band rejection filters and Fabry-P
 érot-like filters. Furthermore\, we design and propose 3-cascaded Mach–Zeh
 nder modulators on the SOI platform and investigate the feasibility of gen
 erating optical frequency combs with such devices. Among the various optic
 al frequency comb generators\, quantum dash mode-locked laser diodes (QD-M
 LLDs) are potential candidates for future WDM transceivers. QD-MLLDs can e
 mit a broadband of optical carriers with a fixed frequency spacing between
  each carrier. In the second part of the thesis\, we demonstrate the perfo
 rmance of such devices to serve high-capacity coherent optical systems and
  conduct a thorough performance comparison between QD-MLLDs and a narrow l
 inewidth integrable tunable laser assembly. Moreover\, we demonstrate that
  such devices can be used not only as multi-wavelength sources at the WDM 
 transmitter but also as multi-wavelength local oscillators at the receiver
  side for coherent detections of WDM signals. Lastly\, thanks to the possi
 bility of hybrid integration\, we propose a schematic for future coherent 
 optical transceivers using chip-scale optical frequency comb sources\, suc
 h as QD-MLLDs\, and silicon photonic modulators.\n\nIn the last part of th
 e thesis\, we propose and verify\, both analytically and experimentally\, 
 innovative encryption techniques to safeguard sensitive data. We propose a
 n encryption technique utilizing a phase modulator at the transmitter side
  and based on a roundtrip mechanism wherein an authenticated user does not
  share the secret key with other entities. Then\, we introduce a quantum-i
 nspired encryption technique for one-way transmission\, which is based on 
 displacing the modulated symbol randomly with random amplitudes and phases
 . Only the authenticated user would be able to decrypt the signal with the
  correct secret key after performing synchronization processes. We finally
  show that the proposed techniques can be used in the existing optical fib
 er links and are protected against eavesdropping attacks wherein adversari
 es tap into the fiber link to steal sensitive information.\n
DTSTART:20240429T174500Z
DTEND:20240429T194500Z
LOCATION:Room 603\, McConnell Engineering Building\, CA\, QC\, Montreal\, H
 3A 0E9\, 3480 rue University
SUMMARY:PhD defence of Mostafa Khalil – Enabling Technologies for Coherent 
  Optical Communications
URL:/ece/channels/event/phd-defence-mostafa-khalil-ena
 bling-technologies-coherent-optical-communications-357104
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