Interferometric intensity correlation: from sensing to imaging

Kassem, Khaled (2024) Interferometric intensity correlation: from sensing to imaging. PhD thesis, University of Glasgow.

Abstract

Second-order intensity correlations (g (2)) of the optical field offer a robust framework for various applications due to their inherent resistance to phase noise and independence from temporal or spatial coherence, relying solely on intensity measurements. This thesis demonstrates the feasibility and advantages of this approach effectively.

The first project applies the g (2) detection method to microscopy. Initially, a single laser beam with a 10 nm bandwidth was used to achieve micron-level axial resolution, demonstrated with a biological sample. We then enhanced the resolution by using two laser beams of 10 nm bandwidth, separated by a wavelength of 150 nm, achieving nanometric axial resolution, as demonstrated by measuring a 5 nm step in a 10-layer graphene sample.

Next, we extend the dual-wavelength approach used in microscopy to synthetic wavelength holography, a technique commonly applied in non-line-of-sight imaging. We demonstrate that our method offers several advantages, including phase noise resistance and enhanced light gathering through the use of a larger aperture, which are crucial in low-light scenarios. This is validated by imaging through various scatterers: first, by imaging through two thin glass diffusers, then through 2.3 cm of optically thick volume scatterer, and finally by showing that we can measure while the scatterer is moving (dynamic), demonstrating our robustness to fluctuations induced by changes in the scattering medium.

Moreover, the potential of a dual-comb laser modality is tested within the experimental setup, aiming to enhance both speed and robustness by eliminating the necessity for mechanical scanning. By leveraging the dual-comb laser’s ability to perform optical delay scanning without mechanical movement, this method offers greater flexibility in terms of range and resolution. Proof-of-principle measurements substantiate this advancement and discuss both the potential of dual-comb lasers and the further developments needed to make them useful and applicable in practical scenarios.

Finally, we highlight the broad range of possible applications for g (2) methods, emphasizing how this work lays the foundation for future projects. By combining these techniques with emerging technologies, there is great potential to tackle new challenges and further expand the impact of this work in various fields.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Faccio, Professor Daniele
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84829
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 24 Jan 2025 15:45
• Last Modified: 29 Jan 2025 12:18
• Thesis DOI: 10.5525/gla.thesis.84829
• URI: https://theses.gla.ac.uk/id/eprint/84829

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