The topic of this dissertation is photonic crystal nanocavities for semiconductor cavity quantum electrodynamics. For the purposes of this study, these nanocavities may be one dimensional (1D) or two dimensional (2D) in design. The 2D devices are active and contain embedded InAs quantum dots (QDs), whereas the 1D devices are passive and contain no active emitters. The 2D photonic crystal nanocavities are fabricated in a slab of GaAs with a single layer of InAs QDs embedded in the slab. When a cavity mode substantially overlaps the QD ensemble, the dots affect the linewidths of the observed modes, leading to broadening of the linewidth at low excitation powers due to absorption and narrowing of the linewidths at high excitation powers due to gain when the QD ensemble absorption is saturated. We observe lasing from a few QDs in such a nanocavity. A technique is discussed with allows us to tune the resonance wavelength of a nanocavity by condensation of an inert gas onto the sample, which is held at cryogenic temperatures. The structural quality at the interfaces of epitaxially grown semiconductor heterostructures is investigated, and a growth instability is discovered which leads to roughness on the bottom of the GaAs slabs. Adjustment of MBE growth parameters leads to the elimination of this roughness, and the result is higher nanocavity quality factors. A number of methods for optimizing the fabrication of nanocavities is presented, which lead to higher quality factors. It is shown that some fundamental limiting factor, not yet fully understood, is preventing high quality factors at wavelengths shorter than 950 nm. Silicon 1D devices without active emitters are investigated by means of a tapered microfiber loop, and high quality factors are observed. This measurement technique is compared to a cross-polarized resonant scattering method. The quality factors observed in the silicon nanocavities are higher than those observed in GaAs, consistent with our observation that quality factors are in general higher at longer wavelengths.

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.

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.

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.

Includes bibliographical references (p. 155-159).

The design and characterization of both electromagnetic bandgap (EBG) and inter-coupled split-ring resonator (SRR) structures utilized in microwave frequencies were proposed and studied. A new double-stopband EBG structure with a passband region of 14 to 18 GHz was initially constructed by determining the critical structural ratios. To reduce the size of EBG structure, a novel tapered array pattern was introduced. The structural period, the number of slot, and the length of slot were examined and a strong correlation was found between the lowpass cutoff frequency and the center slot length. Non-linearly tapered configuration was applied to enhance the filter performance and its size was only 57% of the conventional EBG structure. Inter-coupled SRR was also examined and utilized as a bandpass filter when it is implemented on the microstrip line for the first time. It was found that the proposed structure can provide a fractional bandwidth of over 68% with an insertion loss of 0.81 dB in the passband region with a device size of 15.5 mm. / Chemical bath deposited Cadmium Sulfide (CdS) thin film was applied to the microwave structures to construct switchable filters. The illumination-sensitive CdS thin film's sheet resistance has been demonstrated to be able to switch from 300 to 109 O/square. With the proposed "conductive-islands" implementation, switching of EBG structure's transmission coefficient (S21) was achieved from 31.3 dB to 5.6 dB at 13 GHz. The inter-coupled SRR structure also showed a S21 switching response from 19 dB to 1.5 dB at 5 GHz. Therefore, optically controlled microwave filters were successfully constructed and realized. / Critical contributions in the field of microwave periodic structures are the characterization and the construction of double-stopband structure, linearly and non-linearly tapered array structures, and inter-coupled SRR structures. Vital characteristics and advantages discovered include wide stopband, reduced size, and large fractional bandwidth. Chemical bath deposited CdS thin films were studied to achieve an ultra low sheet resistance and high photosensitivity. Important applications associated with these structures are microwave lowpass/bandpass filters and optically controlled filters.

Recently photonic crystals with a three - dimensional ordered structure with periodicity of the optical wavelength have attracted attention from both fundamental and practical points of view. Control of electromagnetic waves flow in photonic crystals was discussed. The application of photonic crystals is to create tunable band gap materials especially in visible spectra region, where the gap could be controlled by an external parameter. Opal crystal films have been fabricated on solid substrates with a horizontal deposition method. We have studied transmission spectra of synthetic opal, infiltrated with nematic liquid crystal 5CB and demonstrating that the position of the stop band in the visible spectra is shifted to IR wavelength with increasing volume part of 5CB in photonic crystal opal. We show dependence upon stop band position and light incidence angle in bare opal. It is a possibility turning this stop band. Opal filled with LC photonic strength was studied. We demonstrating that photonic strength saturates when was filled about 20% of opal voids.

We have studied inverse opal optical properties. Defects, action on photonic band gab position was discussed. We showed that defect gives us possibility to control light flow in photonic crystal.

Recently photonic crystals with a three - dimensional ordered structure with periodicity of the optical wavelength have attracted attention from both fundamental and practical points of view.Light flow control in photonic crystals was discussed.Opal crystal films have been fabricated on solid substrates with a vertical deposition method.