Kelly, Joseph (2024). Propagation effects within an Extended Optical Amplifier and their impact on the Spatial Distribution of squeezing: towards Quantum Imaging. University of Birmingham. Ph.D.
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Kelly2024PhD.pdf
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Abstract
A continuous laser beam can be viewed as a stream of photons travelling through space. Assuming the generation of each photon is a random and independent process, and they do not interact with each other, they display Poissonian statistics. This leads to random intensity fluctuations on the beam, often referred to as shot noise; this is a limiting factor in many light-based measurements, in particular in imaging.
A technique known as squeezing can be used to reduce this intensity noise at the expense of increasing phase noise, adhering to Heisenberg’s uncertainty principle. Recently, ways of producing squeezed light have been studied extensively. One method, four wave mixing (4WM) in an atomic vapour, has been shown to produce twin beams with a correlated intensity statistics, by acting as a multi-spatial-mode optical parametric amplifier (MSM OPA). Therefore, the intensity difference between the coupled modes is squeezed. Squeezing occurs in multiple spatial modes within the beams, so even localised regions of them are correlated in intensity.
Previously, the focus has been on determining the minimum size of these correlated regions, the coherence area. However, there have been significant challenges in deducing this, which is believed to be due to propagation effects between the coupled modes as they travel through the extended optical parametric amplifier. This leads to the correlated regions not being in an expected place in each beam. As such, the focus of this thesis largely concerns the identifying and untangling this phenomena. Further, a new scheme, SAI, is proposed that aims to compensate for these propagation effects in a fully optical way.
| Type of Work: | Thesis (Doctorates > Ph.D.) | |||||||||
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| Award Type: | Doctorates > Ph.D. | |||||||||
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| Licence: | All rights reserved | |||||||||
| College/Faculty: | Colleges (2008 onwards) > College of Engineering & Physical Sciences | |||||||||
| School or Department: | School of Physics and Astronomy | |||||||||
| Funders: | Engineering and Physical Sciences Research Council | |||||||||
| Subjects: | Q Science > QC Physics | |||||||||
| URI: | http://etheses.bham.ac.uk/id/eprint/14579 |
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