Investigations of high-efficiency mixing and parametric amplification in nonlinear crystals
Investigations of high-efficiency mixing and parametric amplification in nonlinear crystals
This thesis is concerned with the use of difference-frequency mixing and parametric amplification processes in nonlinear crystals to generate high pulsed energies in the near-infrared for use in laser radar. The processes have been investigated both theoretically and experimentally. A complete theoretical treatment of second-order nonlinear interactions between plane waves has been developed. The treatment allows for any intensity of wave and any size of phase mismatch between the waves. It is the first such treatment to give rise to completely analytical results. An analysis of the phase mismatch between beams propagating in a non-collinear geometry in a second-order nonlinear process has been carried out. This analysis leads to the concept of tangential phase matching which results in an enhancement in the acceptance angle of such an interaction and is therefore a valuable technique for use with divergent beams. It has been demonstrated theoretically, for the first time, that in a difference-frequency mixing interaction the tangential phase-matching condition occurs when the angle between the most divergent input beam and the generated beam is equal to the walkoff angle, but in the opposite direction. Some experimental investigations of these interactions have been conducted using lithium niobate. A large enhancement in the conversion efficiency of a difference-frequency mixing experiment has been observed when the tangential phase-matching condition was used. The properties of a parametric amplifier have also been investigated. A gain of 30 was observed for small signals and it was found that the divergence of the amplified beam was not significantly altered by the amplification process. The application of the results established in this thesis will enable future workers to perform more accurate calculations on second-order nonlinear interactions and to achieve higher conversion efficiencies in mixing processes between divergent beams.
University of Southampton
Milton, Martin John Terry
1990
Milton, Martin John Terry
Milton, Martin John Terry
(1990)
Investigations of high-efficiency mixing and parametric amplification in nonlinear crystals.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis is concerned with the use of difference-frequency mixing and parametric amplification processes in nonlinear crystals to generate high pulsed energies in the near-infrared for use in laser radar. The processes have been investigated both theoretically and experimentally. A complete theoretical treatment of second-order nonlinear interactions between plane waves has been developed. The treatment allows for any intensity of wave and any size of phase mismatch between the waves. It is the first such treatment to give rise to completely analytical results. An analysis of the phase mismatch between beams propagating in a non-collinear geometry in a second-order nonlinear process has been carried out. This analysis leads to the concept of tangential phase matching which results in an enhancement in the acceptance angle of such an interaction and is therefore a valuable technique for use with divergent beams. It has been demonstrated theoretically, for the first time, that in a difference-frequency mixing interaction the tangential phase-matching condition occurs when the angle between the most divergent input beam and the generated beam is equal to the walkoff angle, but in the opposite direction. Some experimental investigations of these interactions have been conducted using lithium niobate. A large enhancement in the conversion efficiency of a difference-frequency mixing experiment has been observed when the tangential phase-matching condition was used. The properties of a parametric amplifier have also been investigated. A gain of 30 was observed for small signals and it was found that the divergence of the amplified beam was not significantly altered by the amplification process. The application of the results established in this thesis will enable future workers to perform more accurate calculations on second-order nonlinear interactions and to achieve higher conversion efficiencies in mixing processes between divergent beams.
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Published date: 1990
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Local EPrints ID: 458342
URI: http://eprints.soton.ac.uk/id/eprint/458342
PURE UUID: d06189a6-4737-47c7-ba94-869067f350ce
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Date deposited: 04 Jul 2022 16:46
Last modified: 04 Jul 2022 16:46
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Author:
Martin John Terry Milton
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