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DISCRETE SURFACE SOLITONS
Title
DISCRETE SURFACE SOLITONS.
Creator
Suntsov, Sergiy, Stegeman, George, University of Central Florida
Abstract / Description
Surface waves exist along the interfaces between two different media and are known to display properties that have no analogue in continuous systems. In years past, they have been the subject of many studies in a diverse collection of scientific disciplines. In optics, one of the mechanisms through which optical surface waves can exist is material nonlinearity. Until recently, most of the activity in this area was focused on interfaces between continuous media but no successful experiments...
Show moreSurface waves exist along the interfaces between two different media and are known to display properties that have no analogue in continuous systems. In years past, they have been the subject of many studies in a diverse collection of scientific disciplines. In optics, one of the mechanisms through which optical surface waves can exist is material nonlinearity. Until recently, most of the activity in this area was focused on interfaces between continuous media but no successful experiments have been reported. However, the growing interest that nonlinear discrete optics has attracted in the last two decades has raised the question of whether nonlinear surface waves can exist in discrete optical systems. In this work, a detailed experimental study of linear and nonlinear optical wave propagation at the interface between a discrete one-dimensional Kerr-nonlinear system and a continuous medium (slab waveguide) as well as at the interface between two dissimilar waveguide lattices is presented. The major part of this dissertation is devoted to the first experimental observation of discrete surface solitons in AlGaAs Kerr-nonlinear arrays of weakly coupled waveguides. These nonlinear surface waves are found to localize in the channels at and near the boundary of the waveguide array. The key unique property of discrete surface solitons, namely the existence of a power threshold, is investigated in detail. The second part of this work deals with the linear light propagation properties at the interface between two dissimilar waveguide arrays (so-called waveguide array hetero-junction). The possibility of three different types of linear interface modes is theoretically predicted and the existence of one of them, namely the staggered/staggered mode, is confirmed experimentally. The last part of the dissertation is dedicated to the investigation of the nonlinear properties of AlGaAs waveguide array hetero-junctions. The predicted three different types of discrete hybrid surface solitons are analyzed theoretically. The experimental results on observation of in-phase/in-phase hybrid surface solitons localized at channels on either side of the interface are presented and different nature of their formation is discussed.
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Date Issued
2007
Identifier
CFE0001989, ucf:47426
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001989
QUADRATIC SPATIAL SOLITON INTERACTIONS
Title
QUADRATIC SPATIAL SOLITON INTERACTIONS.
Creator
Jankovic, Ladislav, Stegeman, George I., University of Central Florida
Abstract / Description
Quadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO3) and periodically poled potassium titanyl phosphate (KTP) crystals....
Show moreQuadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO3) and periodically poled potassium titanyl phosphate (KTP) crystals. These particular crystals were desirable for these experiments because of their large nonlinear coefficients and, more importantly, because the experiments could be performed under non-critical-phase-matching (NCPM) conditions. The single soliton generation measurements, performed on KNBO3 by launching the fundamental component only, showed a broad angular acceptance bandwidth which was important for the soliton collisions performed later. Furthermore, at high input intensities multi-soliton generation was observed for the first time. The influence on the multi-soliton patterns generated of the input intensity and beam symmetry was investigated. The combined experimental and theoretical efforts indicated that spatial and temporal noise on the input laser beam induced multi-soliton patterns. Another research direction pursued was intensity dependent soliton routing by using of a specially engineered quadratically nonlinear interface within a periodically poled KTP sample. This was the first time demonstration of the self-reflection phenomenon in a system with a quadratic nonlinearity. The feature investigated is believed to have a great potential for soliton routing and manipulation by engineered structures. A detailed investigation was conducted on two soliton interaction and collision processes. Birth of an additional soliton resulting from a two soliton collision was observed and characterized for the special case of a non-planar geometry. A small amount of spiraling, up to 30 degrees rotation, was measured in the experiments performed. The parameters relevant for characterizing soliton collision processes were also studied in detail. Measurements were performed for various collision angles (from 0.2 to 4 degrees), phase mismatch, relative phase between the solitons and the distance to the collision point within the sample (which affects soliton formation). Both the individual and combined effects of these collision variables were investigated. Based on the research conducted, several all-optical switching scenarios were proposed.
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Date Issued
2004
Identifier
CFE0000090, ucf:46135
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000090
STABLE SPATIAL SOLITONS IN SEMICONDUCTOROPTICAL AMPLIFIERS
Title
STABLE SPATIAL SOLITONS IN SEMICONDUCTOROPTICAL AMPLIFIERS.
Creator
ultanir, erdem ahmet, Stegeman, George I., University of Central Florida
Abstract / Description
A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide.Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in asystem. They have been observed in many different conservative media in the last couple ofyears. Solitons are ubiquitous, because of the probability of using their interactions in opticaldata processing, communications etc. Up to now due to the power required to generate thesolitons, and the response times of...
Show moreA spatial soliton is a shape invariant self guided beam of light or a self induced waveguide.Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in asystem. They have been observed in many different conservative media in the last couple ofyears. Solitons are ubiquitous, because of the probability of using their interactions in opticaldata processing, communications etc. Up to now due to the power required to generate thesolitons, and the response times of the soliton supporting media, these special waves of naturecould not penetrate the applications arena. Semiconductors, with their resonant nonlinearities, arethought to be ideal candidates for fast switching, low power spatial solitons.In this dissertation it is shown theoretically and experimentally that it is possible toobserve stable spatial solitons in a periodically patterned semiconductor optical amplifier(PPSOA). The solitons have unique beam profiles that change only with system parameters, likepumping current, etc. Their coherent and incoherent interactions which could lead to all opticaldevices have been investigated experimentally and theoretically. The formation of filaments ormodulational instability has been studied theoretically and yielded analytical formulae forevaluating the filament gain and the maximum spatial frequencies in PPSOA devices.Furthermore, discrete array amplifiers have been analyzed numerically for discrete solitons, andthe prospect of using multi peak discrete solitons as laser amplifiers is discussed.
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Date Issued
2004
Identifier
CFE0000142, ucf:46153
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000142