FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W827674976> ?p ?o ?g. }

• W827674976 abstract "Disordered media with refractive index variations can be found in the atmosphere, the ocean, and in many materials or biological tissues. Several technologies that make use of such random media, as image formation, satellite communication, astronomy or microscopy, must deal with an unavoidable light scattering or diffusion. This is why for many years light propagation through random media has been a subject of intensive study. Interesting phenomena such as speckle, coherent backscattering or random lasing have been discovered and studied. More recently, researchers are beginning to investigate mechanisms to control light propagation through such media to enhance light transmission and sharpen the focus.&#x0D; On the other hand, it has been known for several years that nonlinear random structures are able to generate light in an ultra-broad frequency range, without the need of angle or temperature tuning. Particularly interesting is the nonlinear light diffusion observed from materials with no change in the refractive index and which appear to be fully diffusion less to linear light propagation. However, a comprehensive understanding of the scattering when a nonlinear interaction takes place has not yet been given. &#x0D; The core of the thesis focuses on the study of the nonlinear light generation and propagation from crystalline structures with disordered nonlinear domains but with a homogenous refractive index. A random distribution of non-linear domains is found naturally in the Strontium Barium Niobate (SBN) ferroelectric crystal. As opposed to other mono-domain nonlinear optical crystals commonly used for frequency up-conversion, such as Potassium Titanyl Phosphate (KTP) or Lithium Niobate (LiNbO3), in SBN the nonlinear domain size is, typically, on the order of the coherence length or many times smaller than the size of the whole crystal. Such domains are usually several times longer in the c-axis direction relative to the plane perpendicular to that axis. Adjacent domains exhibit antiparallel polarization along such crystalline axis, with no change in refractive index. &#x0D; In Chapter 1 we give a brief introduction to light generation and propagation in random media, describing the speckle, light manipulation and second harmonic generation (SHG).&#x0D; In chapter 2, we study the nonlinear light generation and manipulation from a transparent SBN crystal. In its theoretical description we use a two-dimensional random structure consisting of a homogeneous background polarized in one direction with uniform rectangular boundaries, and a group of square reverse polarization domains with random sizes and located in random positions. The SHG from each domain is obtained using the Green's function formalism. In the experiments, we alter the ferroelectric domain structure of the SBN crystal by electric field poling or thermal treatments at different temperatures. The SBN crystal structures after such different treatments are shown to be characterized by their SHG patterns.&#x0D; In chapter 3, by measuring the spatial distribution of the second harmonic light in the c-plane, we demonstrate that the randomness in the nonlinear susceptibility results in a speckle pattern. We explain the observations as a result of the linear interference among the second harmonic waves generated in all directions by each of the nonlinear domains. &#x0D; In chapter 4, we report on our experimental implementation of the wave-front phase modulation method to control and focus the SHG speckle from the random SBN crystal. This research creates a bridge between light phase modulation and nonlinear optics. Finally we perform a theoretical analysis to demonstrate enhanced efficiencies for nonlinear light focusing by the wave-front phase modulation method in different directions. Various types of nonlinear structures are considered, including the homogeneous rectangular crystal, the group of random domains, and the combination of both." @default.
• W827674976 created "2016-06-24" @default.
• W827674976 creator A5041866782 @default.
• W827674976 date "2023-10-15" @default.
• W827674976 modified "2023-10-16" @default.
• W827674976 title "Light generation and manipulation from nonlinear randomly distributed domains in SBN" @default.
• W827674976 doi "https://doi.org/10.5821/dissertation-2117-95412" @default.
• W827674976 hasPublicationYear "2023" @default.
• W827674976 type Work @default.
• W827674976 sameAs 827674976 @default.
• W827674976 citedByCount "0" @default.
• W827674976 crossrefType "dissertation" @default.
• W827674976 hasAuthorship W827674976A5041866782 @default.
• W827674976 hasBestOaLocation W8276749761 @default.
• W827674976 hasConcept C120456961 @default.
• W827674976 hasConcept C120665830 @default.
• W827674976 hasConcept C121332964 @default.
• W827674976 hasConcept C133386390 @default.
• W827674976 hasConcept C158622935 @default.
• W827674976 hasConcept C191486275 @default.
• W827674976 hasConcept C192562407 @default.
• W827674976 hasConcept C2780872166 @default.
• W827674976 hasConcept C2982854487 @default.
• W827674976 hasConcept C40637687 @default.
• W827674976 hasConcept C42067758 @default.
• W827674976 hasConcept C47019982 @default.
• W827674976 hasConcept C49040817 @default.
• W827674976 hasConcept C520434653 @default.
• W827674976 hasConcept C62520636 @default.
• W827674976 hasConcept C69357855 @default.
• W827674976 hasConcept C79090758 @default.
• W827674976 hasConcept C97355855 @default.
• W827674976 hasConceptScore W827674976C120456961 @default.
• W827674976 hasConceptScore W827674976C120665830 @default.
• W827674976 hasConceptScore W827674976C121332964 @default.
• W827674976 hasConceptScore W827674976C133386390 @default.
• W827674976 hasConceptScore W827674976C158622935 @default.
• W827674976 hasConceptScore W827674976C191486275 @default.
• W827674976 hasConceptScore W827674976C192562407 @default.
• W827674976 hasConceptScore W827674976C2780872166 @default.
• W827674976 hasConceptScore W827674976C2982854487 @default.
• W827674976 hasConceptScore W827674976C40637687 @default.
• W827674976 hasConceptScore W827674976C42067758 @default.
• W827674976 hasConceptScore W827674976C47019982 @default.
• W827674976 hasConceptScore W827674976C49040817 @default.
• W827674976 hasConceptScore W827674976C520434653 @default.
• W827674976 hasConceptScore W827674976C62520636 @default.
• W827674976 hasConceptScore W827674976C69357855 @default.
• W827674976 hasConceptScore W827674976C79090758 @default.
• W827674976 hasConceptScore W827674976C97355855 @default.
• W827674976 hasLocation W8276749761 @default.
• W827674976 hasOpenAccess W827674976 @default.
• W827674976 hasPrimaryLocation W8276749761 @default.
• W827674976 hasRelatedWork W1974744100 @default.
• W827674976 hasRelatedWork W1979116355 @default.
• W827674976 hasRelatedWork W2009286461 @default.
• W827674976 hasRelatedWork W2040267084 @default.
• W827674976 hasRelatedWork W2050136570 @default.
• W827674976 hasRelatedWork W2074768796 @default.
• W827674976 hasRelatedWork W2473919384 @default.
• W827674976 hasRelatedWork W2912354114 @default.
• W827674976 hasRelatedWork W827674976 @default.
• W827674976 hasRelatedWork W2185274668 @default.
• W827674976 isParatext "false" @default.
• W827674976 isRetracted "false" @default.
• W827674976 magId "827674976" @default.
• W827674976 workType "dissertation" @default.