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- Title
- Third Order Nonlinearity of Organic Molecules.
- Creator
-
Hu, Honghua, Vanstryland, Eric, Hagan, David, Zeldovich, Boris, Hernandez, Florencio, University of Central Florida
- Abstract / Description
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The main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (?(3)) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities....
Show moreThe main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (?(3)) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities. Both linear (absorption, fluorescence, fluorescence excitation anisotropy) and nonlinear (Z-scan, two-photon fluorescence, pump-probe) techniques are described and utilized to fully characterize the spectroscopic properties of organic molecules in solution or solid-state form. These properties are then analyzed by quantum chemical calculations or other specific quantum mechanical model to understand the origins of the nonlinearities as well as the correlations with their unique molecular structural features. These calculations are performed by collaborators. The 2PA study of organic materials is focused on the structure-2PA property relationships of four groups of dyes with specific molecular design approaches as the following: (1) Acceptor-?-Acceptor dyes for large 2PA cross section, (2) Donor-?-Acceptor dyes for strong solvatochromic effects upon the 2PA spectra, (3) Near-infrared polymethine dyes for a symmetry breaking effect, (4) Sulfur-squaraines vs. oxygen-squaraines to study the role of sulfur atom replacement upon their 2PA spectra. Additionally, the 2PA spectrum of a solid-state single crystal made from a Donor-?-Acceptor dye is measured, and the anisotropic nonlinearity is studied with respect to different incident polarizations. These studies further advance our understanding towards an ultimate goal to a predictive capability for the 2PA properties of organic molecules. The NLR study on molecules is focused on the temporal and spectral dispersion of the nonlinear refraction index, n2, of the molecules. Complicated physical mechanisms, originating from either electronic transitions or nuclei movement, are introduced in general. By adopting a prism compressor / stretcher to control the pulsewidth, an evolution of n2 with respect to incident pulsewidth is measured on a simple inorganic molecule (-)carbon disulfide (CS2) in neat liquid at 700 nm and 1064 nm to demonstrate the pulsewidth dependent nonlinear refraction. The n2 spectra of CS2 and certain organic molecules are measured by femtosecond pulses, which are then analyzed by a 3-level model, a simplified (")Sum-over-states(") quantum mechanical model. These studies can serve as a precursor for future NLR investigations.
Show less - Date Issued
- 2012
- Identifier
- CFE0004387, ucf:49400
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004387
- Title
- FEMTOSECOND LASER WRITTEN VOLUMETRIC DIFFRACTIVE OPTICAL ELEMENTS AND THEIR APPLICATIONS.
- Creator
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Choi, Jiyeon, Richardson, Martin, University of Central Florida
- Abstract / Description
-
Since the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features...
Show moreSince the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features that can be exploited in fabricating photonic structures is the refractive index change which results from the localized energy deposition. The laser processing system for FLDW can be realized as a compact, desktop station, implemented by a laser source, a 3-D stage and focusing optics. Thus, FLDW can be readily adopted for the fabrication of the photonic devices. For instance, it has been widely employed in various areas of photonic device fabrication such as active and passive waveguides, couplers, gratings, opto-fluidics and similar applications. This dissertation describes the use of FLDW towards the fabrication of custom designed diffractive optical elements (DOE's). These are important micro-optical elements that are building blocks in integrated optical devices including on-chip sensors and systems. The fabrication and characterization of laser direct written DOEs in different glass materials is investigated. The design and performance of a range of DOE's is described, especially, laser-written embedded Fresnel zone plates and linear gratings. Their diffractive efficiency as a function of the fabrication parameters is discussed and an optimized fabrication process is realized. The potential of the micro-DOEs and their integration shown in this dissertation will impact on the fabrication of future on-chip devices involving customized DOEs that will serve great flexibility and multi-functional capability on sensing, imaging and beam shaping.
Show less - Date Issued
- 2009
- Identifier
- CFE0002958, ucf:47984
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002958
- Title
- EVALUATION OF THE PHOTO-INDUCED STRUCTURAL MECHANISMS IN CHALCOGENIDE GLASS MATERIALS.
- Creator
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Lopez, Cedric, Richardson, Kathleen, University of Central Florida
- Abstract / Description
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Chalcogenide glasses and their use in a wide range of optical, electronic and memory applications, has created a need for a more thorough understanding of material property variation as a function of composition and in geometries representative of actual devices. This study evaluates compositional dependencies and photo-induced structural mechanisms in As-S-Se chalcogenide glasses. An effective fabrication method for the reproducible processing of bulk chalcogenide materials has been...
Show moreChalcogenide glasses and their use in a wide range of optical, electronic and memory applications, has created a need for a more thorough understanding of material property variation as a function of composition and in geometries representative of actual devices. This study evaluates compositional dependencies and photo-induced structural mechanisms in As-S-Se chalcogenide glasses. An effective fabrication method for the reproducible processing of bulk chalcogenide materials has been demonstrated and an array of tools developed, for the systematic characterization of the resulting material's physical and optical properties. The influence of compositional variation on the physical properties of 13 glasses within the As-S-Se system has been established. Key structural and optical differences have been observed and quantified between bulk glasses and their corresponding as-deposited films. The importance of annealing and aging of the film material and the impact on photosentivity and long term behavior important to subsequent device stability have been evaluated. Photo-induced structures have been created in the thin films using bandgap cw and sub-bandgap femtosecond laser sources and the exposure conditions and their influence on the post-exposure material properties, have been found to have different limitations and driving mechanisms. These mechanisms largely depend on both structural and/or electronic defects, whether initially present in the chalcogenide material or created upon exposure. These defect processes, largely studied previously in individual binary material systems, have now been shown to be consistently present, but varying in extent, across the ternary glass compositions and exposure conditions examined. We thus establish the varying photo-response of these defects as being the major reason for the optical variations observed. Nonlinear optical material properties, as related to the multiphoton processes used in our exposure studies, have been modeled and a tentative explanation for their variation in the context of composition and method of evaluation is presented.
Show less - Date Issued
- 2004
- Identifier
- CFE0000196, ucf:46177
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000196
- Title
- Nonlinear Optical Response of Simple Molecules and Two-Photon Semiconductor Lasers.
- Creator
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Reichert, Matthew, Vanstryland, Eric, Hagan, David, Likamwa, Patrick, Peale, Robert, University of Central Florida
- Abstract / Description
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This dissertation investigates two long standing issues in nonlinear optics: complete characterization of the ultrafast dynamics of simple molecules, and the potential of a two-photon laser using a bulk semiconductor gain medium. Within the Born-Oppenheimer approximation, nonlinear refraction in molecular liquids and gases can arise from both bound-electronic and nuclear origins. Knowledge of the magnitudes, temporal dynamics, polarization and spectral dependences of each of these mechanisms...
Show moreThis dissertation investigates two long standing issues in nonlinear optics: complete characterization of the ultrafast dynamics of simple molecules, and the potential of a two-photon laser using a bulk semiconductor gain medium. Within the Born-Oppenheimer approximation, nonlinear refraction in molecular liquids and gases can arise from both bound-electronic and nuclear origins. Knowledge of the magnitudes, temporal dynamics, polarization and spectral dependences of each of these mechanisms is important for many applications including filamentation, white-light continuum generation, all-optical switching, and nonlinear spectroscopy. In this work the nonlinear dynamics of molecules are investigated in both liquid and gas phase with the recently developed beam deflection technique which measures nonlinear refraction directly in the time domain. Thanks to the utility of the beam deflection technique we are able to completely determine the third-order response function of one of the most important molecular liquids in nonlinear optics, carbon disulfide. This allows the prediction of essentially any nonlinear refraction or two-photon absorption experiment on CS2. Measurements conducted on air (N2 and O2) and gaseous CS2 reveal coherent rotational revivals in the degree of alignment of the ensemble at a period that depends on its moment of inertia. This allows measurement of the rotational and centrifugal distortion constants of the isolated molecules. Additionally, the rotational contribution to the beam deflection measurement can be eliminated thanks to the particular polarization dependence of the mechanism. At a specific polarization, the dominant remaining contribution is due to the bound-electrons. Thus both the bound-electronic nonlinear refractive index of air, and second hyperpolarizability of isolated CS2 molecules, are measured directly. The later agrees well with liquid CS2 measurements, where local field effects are significant. The second major portion of this dissertation addresses the possibility of using bulk semiconductors as a two-photon gain medium. A two-photon laser has been a goal of nonlinear optics since shortly after the original laser's development. In this case, two-photons are emitted from a single electronic transition rather than only one. This processes is known as two-photon gain (2PG). Semiconductors have large two-photon absorption coefficients, which are enhanced by ~2 orders of magnitude when using photons of very different energies, e.g., ??_a?10??_b. This enhancement should translate into large 2PG coefficients as well, given the inverse relationship between absorption and gain. Here, we experimentally demonstrate both degenerate and nondegenerate 2PG in optically excited bulk GaAs via pump-probe experiments. This constitutes, to my knowledge, the first report of nondegenerate two-photon gain. Competition between 2PG and competing processes, namely intervalence band and nondegenerate three-photon absorption (ND-3PA), in both cases are theoretically analyzed. Experimental measurements of ND-3PA agree with this analysis and show that it is enhanced much more than ND-2PG. It is found for both degenerate and nondegenerate photon pairs that the losses dominate the two-photon gain, preventing the possibility of a two-photon semiconductor laser.
Show less - Date Issued
- 2015
- Identifier
- CFE0005874, ucf:50871
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005874
- Title
- TWO-PHOTON 3D OPTICAL DATA STORAGE VIA FLUORESCENCE MODULATION OF FLUORENE DYES BY PHOTOCHROMIC DIARYLETHENES.
- Creator
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Corredor, Claudia, Belfield, Kevin D., University of Central Florida
- Abstract / Description
-
Three-dimensional (3D) optical data storage based on two-photon processes provides highly confined excitation in a recording medium and a mechanism for writing and reading data with less cross talk between multiple memory layers, due to the quadratic dependence of two photon absorption (2PA) on the incident light intensity. The capacity for highly confined excitation and intrinsic 3D resolution affords immense information storage capacity (up to 1012 bits/cm3). Recently, the use of...
Show moreThree-dimensional (3D) optical data storage based on two-photon processes provides highly confined excitation in a recording medium and a mechanism for writing and reading data with less cross talk between multiple memory layers, due to the quadratic dependence of two photon absorption (2PA) on the incident light intensity. The capacity for highly confined excitation and intrinsic 3D resolution affords immense information storage capacity (up to 1012 bits/cm3). Recently, the use of photochromic materials for 3D memory has received intense interest because of several major advantages over current optical systems, including their erasable/rewritable capability, high resolution, and high sensitivity. This work demonstrates a novel two-photon 3D optical storage system based on the modulation of the fluorescence emission of a highly efficient two-photon absorbing fluorescent dye (fluorene derivative) and a photochromic compound (diarylethene). The feasibility of using efficient intermolecular Förster Resonance Energy Transfer (RET) from the non-covalently linked two-photon absorbing fluorescent fluorene derivative to the photochromic diarylethene as a novel read-out method in a two-photon optical data storage system was explored. For the purpose of the development of this novel two-photon 3D optical storage system, linear and two-photon spectroscopic characterization of commercial diarylethenes in solution and in a polymer film and evidence of their cyclization (O→C) and cycloreversion (C→O) reactions induced by two-photon excitation were undertaken. For the development of a readout method, Resonance Energy Transfer (RET) from twophoton absorbing fluorene derivatives to photochromic compounds was investigated under one and two-photon excitation. The Förster's distances and critical acceptor concentrations were determined for non-bound donor-acceptor pairs in homogeneous molecular ensembles. To the best of my knowledge, modulation of the two-photon fluorescence emission of a dye by a photochromic diarylethene has not been reported as a mechanism to read the recorded information in a 3D optical data storage system. This system was demonstrated to be highly stable and suitable for recording data in thick storage media. The proposed RET-based readout method proved to be non-destructive (exhibiting a loss of the initial fluorescence emission less than 20% of the initial emission after 10,000 readout cycles). Potential application of this system in a rewritable-erasable optical data storage system was proved. As part of the strategy for the development of diarylethenes optimized for 3D optical data storage, derivatives containing π-conjugated fluorene molecules were synthesized and characterized. The final part of this reasearch demonstrated the photostability of fluorine derivatives showing strong molecular polarizability and high fluorescence quantum yields. These compounds are quite promising for application in RET-based two-photon 3D optical data storage. Hence, the photostability of these fluorene derivatives is a key parameter to establish, and facilitates their full utility in critical applications.
Show less - Date Issued
- 2007
- Identifier
- CFE0001662, ucf:47210
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001662
- Title
- INVESTIGATION OF REACTIVELY SPUTTERED BORON CARBON NITRIDE THIN FILMS.
- Creator
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Todi, Vinit, Sundaram, Kalpathy, University of Central Florida
- Abstract / Description
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Research efforts have been focused in the development of hard and wear resistant coatings over the last few decades. These protective coatings find applications in the industry such as cutting tools, automobile and machine part etc. Various ceramic thin films like TiN, TiAlN, TiC, SiC and diamond-like carbon (DLC) are examples of the films used in above applications. However, increasing technological and industrial demands request thin films with more complicated and advanced properties. For...
Show moreResearch efforts have been focused in the development of hard and wear resistant coatings over the last few decades. These protective coatings find applications in the industry such as cutting tools, automobile and machine part etc. Various ceramic thin films like TiN, TiAlN, TiC, SiC and diamond-like carbon (DLC) are examples of the films used in above applications. However, increasing technological and industrial demands request thin films with more complicated and advanced properties. For this purpose, B-C-N ternary system which is based on carbon, boron and nitrogen which exhibit exceptional properties and attract much attention from mechanical, optical and electronic perspectives. Also, boron carbonitride (BCN) thin films contains interesting phases such as diamond, cubic BN (c-BN), hexagonal boron nitride (h-BN), B4C, [two]-C3N4. Attempts have been made to form a material with semiconducting properties between the semi metallic graphite and the insulating h-BN, or to combine the cubic phases of diamond and c-BN (BC2N heterodiamond) in order to merge the higher hardness of the diamond with the advantages of c-BN, in particular with its better chemical resistance to iron and oxygen at elevated temperatures. New microprocessor CMOS technologies require interlayer dielectric materials with lower dielectric constant than those used in current technologies to meet RC delay goals and to minimize cross-talk. Silicon oxide or fluorinated silicon oxide (SiOF) materials having dielectric constant in the range of 3.6 to 4 have been used for many technology nodes. In order to meet the aggressive RC delay goals, new technologies require dielectric materials with K<3. BCN shows promise as a low dielectric constant material with good mechanical strength suitable to be used in newer CMOS technologies. For optical applications, the deposition of BCN coatings on polymers is a promising method for protecting the polymer surface against wear and scratching. BCN films have high optical transparency and thus can be used as mask substrates for X-ray lithography. Most of the efforts from different researchers were focused to deposit cubic boron nitride and boron carbide films. Several methods of preparing boron carbon nitride films have been reported, such as chemical vapor deposition (CVD), plasma assisted CVD, pulsed laser ablation and ion beam deposition. Very limited studies could be found focusing on the effect of nitrogen incorporation into boron carbide structure by sputtering. In this work, the deposition and characterization of amorphous thin films of boron carbon nitride (BCN) is reported. The BCN thin films were deposited by radio frequency (rf) magnetron sputtering system. The BCN films were deposited by sputtering from a high purity B4C target with the incorporation of nitrogen gas in the sputtering ambient. Films of different compositions were deposited by varying the ratios of argon and nitrogen gas in the sputtering ambient. Investigation of the oxidation kinetics of these materials was performed to study high temperature compatibility of the material. Surface characterization of the deposited films was performed using X-ray photoelectron spectroscopy and optical profilometry. Studies reveal that the chemical state of the films is highly sensitive to nitrogen flow ratios during sputtering. Surface analysis shows that smooth and uniform BCN films can be produced using this technique. Carbon and nitrogen content in the films seem to be sensitive to annealing temperatures. However depth profile studies reveal certain stoichiometric compositions to be stable after high temperature anneal up to 700[degrees]C. Electrical and optical characteristics are also investigated with interesting results. The optical band gap of the films ranged from 2.0 eV - 3.1 eV and increased with N2/Ar gas flow ratio except at the highest ratio. The optical band gap showed an increasing trend when annealed at higher temperatures. The effect of deposition temperature on the optical and chemical compositions of the BCN films was also studied. The band gap increased with the deposition temperature and the films deposited at 500oC had the highest band gap. Dielectric constant was calculated from the Capacitance-Voltage curves obtained for the MOS structures with BCN as the insulating material. Aluminum was used as the top electrode and the substrate was p-type Si. Effect of N2/Ar gas flow ratio and annealing on the values of dielectric constant was studied and the dielectric constant of 2.5 was obtained for the annealed BCN films. This by far is the lowest value of dielectric constant reported for BCN film deposited by sputtering. Lastly, the future research work on the BCN films that will be carried out as a part of the dissertation is proposed.
Show less - Date Issued
- 2011
- Identifier
- CFE0004033, ucf:49181
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004033
- Title
- Quantum Chemical Studies for the Engineering of Metal Organic Materials.
- Creator
-
Rivera Jacquez, Hector, Masunov, Artem, Balaeff, Alexander, Harper, James, Heider, Emily, Zou, Shengli, Kaden, William, University of Central Florida
- Abstract / Description
-
Metal Organic Materials (MOM) are composed of transition metal ions as connectors and organic ligands as linkers. MOMs have been found to have high porosity, catalytic, and optical properties. Here we study the gas adsorption, color change, and non-linear optical properties of MOMs. These properties can be predicted using theoretical methods, and the results may provide experimentalists with guidance for rational design and engineering of novel MOMs. The theory levels used include semi...
Show moreMetal Organic Materials (MOM) are composed of transition metal ions as connectors and organic ligands as linkers. MOMs have been found to have high porosity, catalytic, and optical properties. Here we study the gas adsorption, color change, and non-linear optical properties of MOMs. These properties can be predicted using theoretical methods, and the results may provide experimentalists with guidance for rational design and engineering of novel MOMs. The theory levels used include semi-empirical quantum mechanical calculations with the PM7 Hamiltonian and, Density Functional Theory (DFT) to predict the geometry and electronic structure of the ground state, and Time Dependent DFT (TD-DFT) to predict the excited states and the optical properties.The molecular absorption capacity of aldoxime coordinated Zn(II) based MOMs (previously measured experimentally) is predicted by using PM7 Theory level. The 3D structures were optimized with and without host molecules inside the pores. The absorption capacity of these crystals was predicted to be 8H2 or 3N2 per unit cell. When going beyond this limit, the structural integrity of the bulk material becomes fractured and microcrystals are observed both experimentally and theoretically.The linear absorption properties of Co(II) based complexes are known to change color when the coordination number is altered. In order to understand the mechanism of this color change TD-DFT methods are employed. The chromic behavior of the Co(II) based complexes studied was confirmed to be due to a chain in coordination number that resulted in lower metal to ligand distances. These distances destabilize the occupied metal d orbitals, and as a consequence of this, the metal to ligand transition energy is lowered enough to allow the crystals to absorb light at longer wavelengths.Covalent organic frameworks (COFs) present an extension of MOM principles to the main group elements. The synthesis of ordered COFs is possible by using predesigned structures andcarefully selecting the building blocks and their conditions for assembly. The crystals formed by these systems often possess non-linear optical (NLO) properties. Second Harmonic Generation (SHG) is one of the most used optical processes. Currently, there is a great demand for materials with NLO optical properties to be used for optoelectronic, imaging, sensing, among other applications. DFT calculations can predict the second order hyperpolarizability ?2 and tensor components necessary to estimate NLO. These calculations for the ?2 were done with the use of the Berry's finite field approach. An efficient material with high ?2 was designed and the resulting material was predicted to be nearly fivefold higher than the urea standard.Two-photon absorption (2PA) is another NLO effect. Unlike SHG, it is not limited to acentric material and can be used development of in vivo bio-imaging agents for the brain. Pt(II) complexes with porphyrin derivatives are theoretically studied for that purpose. The mechanism of 2PA enhancement was identified. For the most efficient porphyrin, the large 2PA cross-section was found to be caused by a HOMO-LUMO+2 transition. This transition is strongly coupled to 1PA allowed Q-band HOMO-LUMO states by large transition dipoles. Alkyl carboxyl substituents delocalize the LUMO+2 orbital due to their strong ?-acceptor effect, enhancing transition dipoles and lowering the 2PA transition to the desirable wavelengths range.The mechanism 2PA cross-section enhancement of aminoxime and aldoxime ligands upon metal addition of is studied with TD-DFT methods. This mechanism of enhancement is found to be caused by the polarization of the ligand orbitals by the metal cation. After polarization an increase in ligand to ligand transition dipole moment. This enhancement of dipole moment is related to the increase in 2PA cross-sections.
Show less - Date Issued
- 2015
- Identifier
- CFE0005990, ucf:50777
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005990
- Title
- Light-Matter Interactions of Plasmonic Nanostructures.
- Creator
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Reed, Jennifer, Zou, Shengli, Belfield, Kevin, Zhai, Lei, Hernandez, Eloy, Vanstryland, Eric, University of Central Florida
- Abstract / Description
-
Light interaction with matter has long been an area of interest throughout history, spanning many fields of study. In recent decades, the investigation of light-matter interactions with nanostructures has become an intense area of research in the field of photonics. Metallic nanostructures, in particular, are of interest due to the interesting properties that arise when interacting with light. The properties are a result of the excitation of surface plasmons which are the collective...
Show moreLight interaction with matter has long been an area of interest throughout history, spanning many fields of study. In recent decades, the investigation of light-matter interactions with nanostructures has become an intense area of research in the field of photonics. Metallic nanostructures, in particular, are of interest due to the interesting properties that arise when interacting with light. The properties are a result of the excitation of surface plasmons which are the collective oscillation of the conduction electrons in the metal. Since the conduction electrons can be thought of as harmonic oscillators, they are quantized in a similar fashion. Just as a photon is a quantum of oscillations of an electromagnetic field, the plasmon is a quantum of electron oscillations of a metal. There are three types of plasmons:1. Bulk plasmons, also called volume plasmons, are longitudinal density fluctuations which propagate through a bulk metal with an eigenfrequency of ?_p called the plasma frequency.2. Localized surface plasmons are non-propagating excitations of the conduction electrons of a metallic nanoparticle coupled to an electromagnetic field. 3. Surface plasmon polaritons are evanescent, dispersive propagating electromagnetic waves formed by a coupled state between a photon and the excitation of the surface plasmons. They propagate along the surface of a metal-dielectric interface with a broad spectrum of eigenfrequencies from ?=0 to ?= ?_p??2. Plasmonics is a subfield of photonics which focuses on the study of surface plasmons and the optical properties that result from light interacting with metal films and nanostructures on the deep subwavelength scale. In this thesis, plasmonic nanostructures are investigated for optical waveguides and other nanophotonic applications through computational simulations primarily base on electrodynamic theory. The theory was formulated by several key figures and established by James Clerk Maxwell after he published a set of relations which describe all classical electromagnetic phenomena, known as Maxwell's equations. Using methods based on Maxwell's equations, the optical properties of metallic nanostructures utilizing surface plasmons is explored. In Chapter 3, light propagation of bright and dark modes of a partially and fully illuminated silver nanorod is investigated for waveguide applications. Then, the origin of the Fano resonance line shape in the scattering spectra of a silver nanorod is investigated. Next, in Chapter 4, the reflection and transmission of a multilayer silver film is simulated to observe the effects of varying the dielectric media between the layers on light propagation. Building on the multilayer film work, metal-insulator-metal waveguides are explored by perforating holes in the bottom layer of a two layer a silver film to investigate the limits of subwavelength light trapping, confinement, and propagation. Lastly, in Chapter 5, the effect of surface plasmons on the propagation direction of electromagnetic wave around a spherical silver nanoparticle which shows an effective negative index of refraction is examined. In addition, light manipulation using a film of silver prisms with an effective negative index of refraction is also investigated. The silver prisms demonstrate polarization selective propagation for waveguide and optical filter applications. These studies provide insight into plasmonic mechanisms utilized to overcome the diffraction limit of light. Through better understanding of how to manipulating light with plasmonic nanostructures, further advancements in nanophotonic technologies for applications such as extremely subwavelength waveguides, sensitive optical detection, optical filters, polarizers, beam splitters, optical data storage devices, high speed data transmission, and integrated subwavelength photonic circuits can be achieved.
Show less - Date Issued
- 2013
- Identifier
- CFE0005049, ucf:49964
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005049
- Title
- Optical Properties of Single Nanoparticles and Two-dimensional Arrays of Plasmonic Nanostructures.
- Creator
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Zhou, Yadong, Zou, Shengli, Harper, James, Zhai, Lei, Chen, Gang, Zheng, Qipeng, University of Central Florida
- Abstract / Description
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The tunability of plasmonic properties of nanomaterials makes them promising in many applications such as molecular detection, spectroscopy techniques, solar energy materials, etc. In the thesis, we mainly focus on the interaction between light with single nanoparticles and two-dimensional plasmonic nanostructures using electrodynamic methods. The fundamental equations of electromagnetic theory: Maxwell's equations are revisited to solve the problems of light-matter interaction, particularly...
Show moreThe tunability of plasmonic properties of nanomaterials makes them promising in many applications such as molecular detection, spectroscopy techniques, solar energy materials, etc. In the thesis, we mainly focus on the interaction between light with single nanoparticles and two-dimensional plasmonic nanostructures using electrodynamic methods. The fundamental equations of electromagnetic theory: Maxwell's equations are revisited to solve the problems of light-matter interaction, particularly the interaction of light and noble nanomaterials, such as gold and silver. In Chapter 1, Stokes parameters that describe the polarization states of electromagnetic wave are presented. The scattering and absorption of a particle with an arbitrary shape are discussed. In Chapter 2, several computational methods for solving the optical response of nanomaterials when they are illuminated by incident light are studied, which include the Discrete Dipole Approximation (DDA) method, the coupled dipole (CD) method, etc. In Chapter 3, the failure and reexamination of the relation between the Raman enhancement factor and local enhanced electric field intensity is investigated by placing a molecular dipole in the vicinity of a silver rod. Using a silver rod and a molecular dipole, we demonstrate that the relation generated using a spherical nanoparticle cannot simply be applied to systems with particles of different shapes. In Chapter 4, a silver film with switchable total transmission/reflection is discussed. The film is composed of two-dimensional rectangular prisms. The factors affecting the transmission (reflection) as well as the mechanisms leading to the phenomena are studied. Later, in Chapter 5 and 6, the sandwiched nano-film composed of two 2D rectangular prisms arrays and two glass substrates with a continuous film in between is examined to enhance the transmission of the continuous silver film.
Show less - Date Issued
- 2018
- Identifier
- CFE0007117, ucf:51943
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007117