As the performance of computers has improved dramatically since the 1990s, many interesting photonic crystal properties have been theoretically and experimentally discovered. For example, the strong coupling between photonic crystal cavities was revealed in the 2000s; many groups have successfully fabricated these cavities and verified strong coupling experimentally using silicon. In this thesis, instead of using silicon, we present new results on photonic crystals made by thin indium tin oxide (ITO) layers. Compared to silicon, ITO is not an ideal material to make a photonic crystal because of its comparatively low refractive index and limited transparency. However, it is an interesting model material for experiments in photoemission electron microscopy (PEEM). ITO has a high conductivity that mitigates surface charge-up in an electron microscope and allows electron emission after 2-photon absorption with visible light. We are interested in PEEM because it enables the visualization of the propagation of light with nanometer resolution, i.e., below the optical diffraction limit. In this thesis, we theoretically study ITO photonic crystals in one or two-dimensions with the help of the finite-difference time-domain (FDTD) software. We analyze the electromagnetic field distribution in a manner that the field distributions can directly be compared to experimental PEEM results. We also simulate the strong coupling effect between neighboring cavities and illustrate it in terms of the classical oscillator model.

Thesis (M.E.E.)--University of Delaware, 2006. / Principal faculty advisor: James Kolodzey, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Nonlinear optical phenomena associated with high-order soliton breakup in photonic crystal fibres and squeezed state generation in three dimensional photonic crystal microcavities are investigated. In both cases, the properties of periodically patterned, high-index contrast dielectric structures are engineered to control the dispersion and local field enhancements of the electromagnetic field. Ultra-short pulse propagation in a polarization-maintaining microstructured fibre (with 1 um core diameter and 1.1 m length) is investigated experimentally and theoretically. For an 80 MHz train of 130 fs pulses with average propagating powers in the fibre up to 13.8 mW, the output spectra consist of multiple discrete solitons that shift continuously to lower energies as they propagate in the lowest transverse mode of the fibre. The number of solitons and the amount that they shift both increase with the launched power. All of the data is quantitatively consistent with solutions of the nonlinear Schrodinger equation, but only when the Raman nonlinearity is treated without approximation, and self-steepening is included. The feasibility of using a parametric down-conversion process to generate squeezed electromagnetic states in 3D photonic crystal microcavity structures is investigated for the first time. The spectrum of the squeezed light is theoretically calculated by using an open cavity quantum mechanical formalism. The cavity communicates with two main channels, which model vertical radiation losses and coupling into a single-mode waveguide respectively. The amount of squeezing is determined by the correlation functions relating the field quadratures of light coupled into the waveguide. All of the relevant model parameters are realistically estimated using 3D finite-difference time-domain (FDTD) simulations. Squeezing up to ~20% below the shot noise level is predicted for reasonable optical excitation levels. To preserve the squeezed nature of the light generated in the microcavity, a unidirectional coupling geometry from the microcavity to a ridge waveguide in a slab photonic crystal structure is studied. The structure was successfully fabricated in a silicon membrane, and experimental measurements of the efficiency for the signal coupled out of the structure are in good agreement with the result of FDTD simulations. The coupling efficiency of the cavity mode to the output channel is ~60%.

In this thesis we study the role of nonradiative degrees of freedom on quantum optical properties of mesoscopic quantum dots placed in the structured electromagnetic reservoir of a photonic crystal. We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption lineshape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the ``colored" electromagnetic vacuum of a photonic band gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. Phonon sidebands in an ordinary electromagnetic reservoir are recaptured in a simple model of optical phonons using a mean-field factorization of the atomic and lattice displacement operators. Our formalism is then used to treat the non-Markovian dynamics of the same system within the structured electromagnetic density of states of a photonic crystal. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to enhanced lifetime of a photon-atom bound state in a PBG by (i) dephasing and reducing the transition electric dipole moment of the atom and (ii) reducing the quantum mechanical overlap of the state vectors of the excited and ground state (polaronic shift). This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (break-up of phonons into lower energy phonons) and purely nonradiative decay. We demonstrate how these additional damping effects limit the extent of the polaronic (Franck-Condon) shift of the atomic excited state. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption lineshapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

The present thesis describes a novel photonic crystal platform dubbed the photonic nose, a color-based analogue of the human olfactory system. The platform is founded on a one dimensional photonic crystal architecture known as Bragg stacks, which are fabricated using bottom-up self-assembly approaches. Structural and compositional aspects of this novel class of photonic crystals are established that provide them with functionality and utility. Silicon dioxide, titanium dioxide, tin oxide, clays and zeolites are among the materials incorporated into one-dimensional photonic structures. Retention of materials functionality is demonstrated by vapor and liquid sensing experiments. This class of Bragg stacks displays well defined optical properties that have been thoroughly investigated by use of spectroscopic ellipsometry, as we demonstrate in a chapter dedicated to the technique. Utilizing conventional building blocks comprised of nanostructured silicon and titanium dioxide we discuss various aspects of technique pertaining single layered as well as multilayered films. In terms of practical applications these kinds of Bragg stacks show significant potential in areas such as display and sensors that exploit their vibrant and tunable colors. These colors are an important attribute of photonic crystals with bandgaps in the visible range and in this thesis work we present new approaches for characterizing photonic crystal color using well established methods from the field of color imagery. With this knowhow we have been able to assemble a pixilated array of chemically functionalized Bragg stacks in which each pixel responds differently to vapor phase analytes. The combinatorial response of the entire array enables a unique diagnostic fingerprint of a given analyte vapor as determined from color imagery and multivariate statistical methods of analysis. It was possible to discriminate between ethanol, butanol, hexanol, hexane, octane and decane. We also demonstrate the power of the photonic nose platform by distinguishing different bacteria from a photonic nose color analysis of the complex mixture of vapors in the bacteria culture headspace. Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa could be discriminated based on this technique.

In this thesis we study the role of nonradiative degrees of freedom on quantum optical properties of mesoscopic quantum dots placed in the structured electromagnetic reservoir of a photonic crystal. We derive a quantum theory of the role of acoustic and optical phonons in modifying the optical absorption lineshape, polarization dynamics, and population dynamics of a two-level atom (quantum dot) in the ``colored" electromagnetic vacuum of a photonic band gap (PBG) material. This is based on a microscopic Hamiltonian describing both radiative and vibrational processes quantum mechanically. Phonon sidebands in an ordinary electromagnetic reservoir are recaptured in a simple model of optical phonons using a mean-field factorization of the atomic and lattice displacement operators. Our formalism is then used to treat the non-Markovian dynamics of the same system within the structured electromagnetic density of states of a photonic crystal. We elucidate the extent to which phonon-assisted decay limits the lifetime of a single photon-atom bound state and derive the modified spontaneous emission dynamics due to coupling to various phonon baths. We demonstrate that coherent interaction with undamped phonons can lead to enhanced lifetime of a photon-atom bound state in a PBG by (i) dephasing and reducing the transition electric dipole moment of the atom and (ii) reducing the quantum mechanical overlap of the state vectors of the excited and ground state (polaronic shift). This results in reduction of the steady-state atomic polarization but an increase in the fractionalized upper state population in the photon-atom bound state. We demonstrate, on the other hand, that the lifetime of the photon-atom bound state in a PBG is limited by the lifetime of phonons due to lattice anharmonicities (break-up of phonons into lower energy phonons) and purely nonradiative decay. We demonstrate how these additional damping effects limit the extent of the polaronic (Franck-Condon) shift of the atomic excited state. We also derive the modified polarization decay and dephasing rates in the presence of such damping. This leads to a microscopic, quantum theory of the optical absorption lineshapes. Our model and formalism provide a starting point for describing dephasing and relaxation in the presence of external coherent fields and multiple quantum dot interactions in electromagnetic reservoirs with radiative memory effects.

The present thesis describes a novel photonic crystal platform dubbed the photonic nose, a color-based analogue of the human olfactory system. The platform is founded on a one dimensional photonic crystal architecture known as Bragg stacks, which are fabricated using bottom-up self-assembly approaches. Structural and compositional aspects of this novel class of photonic crystals are established that provide them with functionality and utility. Silicon dioxide, titanium dioxide, tin oxide, clays and zeolites are among the materials incorporated into one-dimensional photonic structures. Retention of materials functionality is demonstrated by vapor and liquid sensing experiments. This class of Bragg stacks displays well defined optical properties that have been thoroughly investigated by use of spectroscopic ellipsometry, as we demonstrate in a chapter dedicated to the technique. Utilizing conventional building blocks comprised of nanostructured silicon and titanium dioxide we discuss various aspects of technique pertaining single layered as well as multilayered films. In terms of practical applications these kinds of Bragg stacks show significant potential in areas such as display and sensors that exploit their vibrant and tunable colors. These colors are an important attribute of photonic crystals with bandgaps in the visible range and in this thesis work we present new approaches for characterizing photonic crystal color using well established methods from the field of color imagery. With this knowhow we have been able to assemble a pixilated array of chemically functionalized Bragg stacks in which each pixel responds differently to vapor phase analytes. The combinatorial response of the entire array enables a unique diagnostic fingerprint of a given analyte vapor as determined from color imagery and multivariate statistical methods of analysis. It was possible to discriminate between ethanol, butanol, hexanol, hexane, octane and decane. We also demonstrate the power of the photonic nose platform by distinguishing different bacteria from a photonic nose color analysis of the complex mixture of vapors in the bacteria culture headspace. Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa could be discriminated based on this technique.

No description available.

This thesis describes the investigation of photonic crystals as a substrate in microstrip phased array antennas. Alumina with a relative dielectric constant of 9.6 is used as substrate to obtain miniaturization of the components in the high-frequency range. The proposed design consists of four rectangular patches in a linear array conguration operating at 12 GHz. The antenna elements are excited by a microstrip feed line using the inset feeding technique for perfect impedance matching. A beam steering of 20o is achieved using a switched line phase shifter. Antenna parameters, including impedance matching, bandwidth, gain, directivity and the S parameters of the proposed array antenna are obtained. The simulation results are obtained with the Advanced Design System (ADS) simulator.

Photonic crystal is the periodic structure with different refractive index media. Its photonic-bandgap characteristics could be used to make the photonic crystal lasers. Because of the difficulty of fabrication, the development of three-dimensional photonic crystal is far behind the two-dimensional and one-dimensional photonic crystals. Blue phase liquid crystals are formed by periodic lattice structure with double-twisted cylinder, therefore it is a three-dimensional self-assembled photonic crystal. The objective in this study is to fabricate the three-dimensional photonic crystal blue phase liquid crystal laser by investigating the materials and the fabricating conditions. In this thesis, we doped the laser dye in the blue phase liquid crystal to make the laser device. Firstly, we studied blue phase temperature range and Bragg reflection wavelength under different material ratio. The blue phase lattice structures under different cool rate and surface treatment could be investigated by observing Kossel diagram . According to the experiment results, three-dimensional blue phase photonic crystal laser under room temperature could be achieved through appropriate material ratio, and its Bragg reflection wavelength is corresponds to the emission spectrum of the doped laser dye. By decreasing the cooling rate and the adapting homogeneous alignment of the substrates, the laser output will become more stable. As the result, we successfully fabricated the three-dimensional liquid crystal blue phase laser device at room temperature, and measured three-dimensional laser output. In addition, We study the relations between the laser emission direction and the alignment direction, and the temperature tuning characteristics of the laser wavelength. These results are very useful for the development of the three dimension tunable laser.