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Ultra-broadband frequency generation in a cavity confined Raman medium

Rose, CS 2013, Ultra-broadband frequency generation in a cavity confined Raman medium , PhD thesis, University of Salford.

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Abstract

Throughout the past few decades, science has progressed towards the ability to probe many extremely fast processes and a large amount of research has been aimed at the area of few-femtosecond pulse generation. This thesis describes the generation of coherent broadband radiation through two-colour pumping of molecular hydrogen confined to a unidirectional ring cavity, and the subsequent synthesis of high peak power and few-femtosecond pulses. A set of normalised semi-classical field equations are derived in Bloch form describing the process of ultra-broadband multi-frequency Raman generation or UMRG, and a 3-wave gain suppression analysis is derived from a subset of the plane wave UMRG field equations which describes gain suppression within the ring cavity in terms of both medium and cavity parameters. The gain suppression analysis is further generalised to include finite levels of linear two-photon frequency detuning of the pump beams. Simulations of the plane wave ultra-broadband multi-frequency Raman (UMRG) equations show that a broad frequency spectrum of mutually coherent sideband can be generated. The inverse Fourier transform of spectra generated in this way yields a train of high power near Fourier limited pulses in the time domain which can range from a few-femtoseconds in duration to tens of attoseconds with repetition rates equal to the Raman transition frequency. Pulses synthesised in this way are limited only by the level of medium dispersion, the reflection bandwidth of the chosen coupling mirror and the chosen Raman medium. Simulations of the transverse UMRG equations within the ring cavity geometry have shown ring cavity enhanced UMRG to be resilient to transverse effects such as finite beam width, beam diffraction and the transverse beam separation of the applied pump beams.

Item Type: Thesis (PhD)
Contributors: McDonald, GS (Supervisor)
Themes: Energy
Subjects outside of the University Themes
Schools: Schools > School of Computing, Science and Engineering
Schools > School of Computing, Science and Engineering > Salford Innovation Research Centre (SIRC)
Funders: Engineering and Physical Sciences Research Council (EPSRC)
Depositing User: CS Rose
Date Deposited: 28 Jun 2014 15:35
Last Modified: 30 Nov 2015 23:54
URI: http://usir.salford.ac.uk/id/eprint/31828

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