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University of St. Andrews

1. McLenaghan, Joanna Siân. Negative frequency waves in optics : control and investigation of their generation and evolution .

Degree: 2014, University of St. Andrews

This thesis is concerned with various methods for the control and investigation of pulse dynamics in a Photonic Crystal Fibre (PCF) and of the radiation driven by a short pulse. In particular the focus is on pulses in the anomalous dispersion region which would form solitons in the absence of higher order effects. Several different types of radiation can be driven by such pulses if they are perturbed by higher order dispersive and non-linear effects - for example Resonant Radiation (RR) and Negative Resonant Radiation (NRR) two dispersive waves which gain energy at the expense of the pulse. The feature of NRR which is of particular importance is that it is the first observed example of a coupling between positive and negative frequencies in optics. This has only been possible due to recent advances in fields such as PCFs, lasers and analogue systems. As with many scientific discoveries, NRR was found by bringing together ideas and techniques from these different fields. Both the pulse and the driven radiation are investigated using a number of different pulse and PCF parameters. These include power, chirp, polarisation and PCF dispersion. These are used to vary the wavelengths at which the driven radiation occurs as well as its generation efficiency. Furthermore the power and chirp are used to vary where in the PCF the driven radiation is generated by controlling where the driving pulse compresses and spectrally expands. This property is used to investigate different stages in the evolution of the pulse and driven radiation as well as to optimise the generation efficiency of the driven radiation. Advisors/Committee Members: König, Friedrich (advisor).

Subjects/Keywords: Non-linear optics; Photonic crystal fibres; Solitons; Pulse compression; Negative frequencies; Resonant radiation; Analogue Hawking radiation; Pulse chirp; Short pulse dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

McLenaghan, J. S. (2014). Negative frequency waves in optics : control and investigation of their generation and evolution . (Thesis). University of St. Andrews. Retrieved from http://hdl.handle.net/10023/6532

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

McLenaghan, Joanna Siân. “Negative frequency waves in optics : control and investigation of their generation and evolution .” 2014. Thesis, University of St. Andrews. Accessed March 08, 2021. http://hdl.handle.net/10023/6532.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

McLenaghan, Joanna Siân. “Negative frequency waves in optics : control and investigation of their generation and evolution .” 2014. Web. 08 Mar 2021.

Vancouver:

McLenaghan JS. Negative frequency waves in optics : control and investigation of their generation and evolution . [Internet] [Thesis]. University of St. Andrews; 2014. [cited 2021 Mar 08]. Available from: http://hdl.handle.net/10023/6532.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

McLenaghan JS. Negative frequency waves in optics : control and investigation of their generation and evolution . [Thesis]. University of St. Andrews; 2014. Available from: http://hdl.handle.net/10023/6532

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Exeter

2. Bugler-Lamb, Samuel Lloyd. The quantum vacuum near time-dependent dielectrics.

Degree: PhD, 2017, University of Exeter

The vacuum, as described by Quantum Field Theory, is not as empty as classical physics once led us to believe. In fact, it is characterised by an infinite energy stored in the ground state of its constituent fields. This infinite energy has real, tangible effects on the macroscopic clusters of matter that make up our universe. Moreover, the configuration of these clusters of matter within the vacuum in turn influences the form of the vacuum itself and so forth. In this work, we shall consider the changes to the quantum vacuum brought about by the presence of time-dependent dielectrics. Such changes are thought to be responsible for phenomena such as the simple and dynamical Casimir effects and Quantum Friction. After introducing the physical and mathematical descriptions of the electromagnetic quantum vacuum, we will begin by discussing some of the basic quasi-static effects that stem directly from the existence of an electromagnetic ground state energy, known as the it{zero-point energy}. These effects include the famous Hawking radiation and Unruh effect amongst others. We will then use a scenario similar to that which exhibits Cherenkov radiation in order to de-mystify the 'negative frequency' modes of light that often occur due to a Doppler shift in the presence of media moving at a constant velocity by showing that they are an artefact of the approximation of the degrees of freedom of matter to a macroscopic permittivity function. Here, absorption and dissipation of electromagnetic energy will be ignored for simplicity. The dynamics of an oscillator placed within this moving medium will then be considered and we will show that when the motion exceeds the speed of light in the dielectric, the oscillator will begin to absorb energy from the medium. It will be shown that this is due to the reversal of the 'radiation damping' present for lower velocity of stationary cases. We will then consider how the infinite vacuum energy changes in the vicinity, but outside, of this medium moving with a constant velocity and show that the presence of matter removes certain symmetries present in empty space leading to transfers of energy between moving bodies mediated by the electromagnetic field. Following on from this, we will then extend our considerations by including the dissipation and dispersion of electromagnetic energy within magneto-dielectrics by using a canonically quantised model referred to as 'Macroscopic QED'. We will analyse the change to the vacuum state of the electromagnetic field brought about by the presence of media with an arbitrary time dependence. It will be shown that this leads to the creation of particles tantamount to exciting the degrees of freedom of both the medium and the electromagnetic field. We will also consider the effect these time-dependencies have on the two point functions of the field amplitudes using the example of the electric field. Finally, we will begin the application of the macroscopic QED model to the path integral methods of quantum field theory with the purpose of making…

Subjects/Keywords: 530; quantum; vacuum; casimir; friction; hawking; dynamic casimir; zero point energy; negative frequency; negative frequencies; unruh effect; quantum field theory; dielectric; magneto-dielectric; harmonic; oscillator; path integral; schwinger; keldysh; time-dependent; correlation; electromagnetic; evanescent; polariton; macroscopic; QED; microscopic

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Bugler-Lamb, S. L. (2017). The quantum vacuum near time-dependent dielectrics. (Doctoral Dissertation). University of Exeter. Retrieved from http://hdl.handle.net/10871/29879

Chicago Manual of Style (16th Edition):

Bugler-Lamb, Samuel Lloyd. “The quantum vacuum near time-dependent dielectrics.” 2017. Doctoral Dissertation, University of Exeter. Accessed March 08, 2021. http://hdl.handle.net/10871/29879.

MLA Handbook (7th Edition):

Bugler-Lamb, Samuel Lloyd. “The quantum vacuum near time-dependent dielectrics.” 2017. Web. 08 Mar 2021.

Vancouver:

Bugler-Lamb SL. The quantum vacuum near time-dependent dielectrics. [Internet] [Doctoral dissertation]. University of Exeter; 2017. [cited 2021 Mar 08]. Available from: http://hdl.handle.net/10871/29879.

Council of Science Editors:

Bugler-Lamb SL. The quantum vacuum near time-dependent dielectrics. [Doctoral Dissertation]. University of Exeter; 2017. Available from: http://hdl.handle.net/10871/29879

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