Skip to main content

Photonic Time-Stretch Enabled High Throughput Microwave and MM-Wave Interferometry Applied to Fibre Grating Sensors and Non-Contact Measurement

Ahmad, Eamonn (2019) Photonic Time-Stretch Enabled High Throughput Microwave and MM-Wave Interferometry Applied to Fibre Grating Sensors and Non-Contact Measurement. Doctor of Philosophy (PhD) thesis, University of Kent, Vrije Universiteit Brussel. (KAR id:74399)

Language: English
Click to download this file (8MB) Preview
[thumbnail of 303EJ_Thesis_UKent.pdf]
This file may not be suitable for users of assistive technology.
Request an accessible format


The research presented in this thesis is focused towards developing real-time, high-speed applications, employing ultrafast optical microwave generation and characterisation techniques. This thesis presents a series of experiments wherein mode-locked laser pulses are utilised. Photonics-based microwave and MM-Wave generation and detection are explored and employed for applications pertaining to fibre grating sensors and non-contact measurement. The application concepts leverage techniques from optical coherence tomography and non-destructive evaluation of turbid media. In particular, I use the principle of dispersion-induced photonic Time-Stretch to slow down high-speed waveforms to speeds usable by state-of-the-art photo-detectors and digital signal processors. The concept of photonic time-stretch is applied to map instantaneous microwave frequency to the time instant of the signal, which in turn is related to spatial location as established by the space-wavelength-time conversions. The experimental methods applied throughout this thesis is based upon Michelson interferometer architecture.

My original contribution to knowledge is the realisation of Photonics-based, single tone, and chirped microwave and MM-Wave pulse generation applied to deciphering physical strain profile along the length of a chirped fibre Bragg grating employed in a Michelson interferometer configuration. This interrogation scheme allows intra-grating high-resolution, high-speed, and temperature independent strain measurement. This concept is further extended to utilise photonic generation of microwave pulses to characterise surface profile information of thin film and thin plate infrared transparent slides of variable thickness setup in a Michelson interferometer architecture. The method basis for photonically generated high-frequency microwave signals utilises the principle of photonic Time-Stretch. The research was conducted in the Photonics Lab at the University of Kent. In addition, the photonically generated microwave/ MM-Wave pulses is utilised as a potential broadband frequency-swept source for non-contact measurement of turbid media. Investigation of the proof-of-concept based on an MM-Wave coherence tomography set-up is implemented at Vrije Universiteit Brussel (VUB), Department of Electronics and Informatics (ETRO).

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Wang, Dr Chao
Thesis advisor: Stiens, Prof Johan
Uncontrolled keywords: Microwave Photonics, Ultrafast electronics, Fibre Bragg Sensors, Chirped Fibre Bragg Gratings, MM-Waves, Non-Contact Sensing, Dimensional Metrology
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
SWORD Depositor: System Moodle
Depositing User: System Moodle
Date Deposited: 14 Jun 2019 09:10 UTC
Last Modified: 11 Dec 2022 08:38 UTC
Resource URI: (The current URI for this page, for reference purposes)
  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.