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Analytical solution of band gaps in two-dimensional (2-D) photonic crystals made by multi-beam interference is described. The analytical approach is the first order approximation of the solution of the PC with step distribution of refractive index and it is accurate only for low refractive index modulation materials.

One-photon mass-analyzed threshold ionization (MATI) spectrum of trans-[C.sub.2][H.sub.2][Cl.sub.2] is obtained by using vacuum ultraviolet radiation generated by four-wave mixing in Kr. The spectrum has displayed abundant overtones and combinations and the equilibrium geometry of the cation is estimated through the Franck-Condon fit.

We propose a pair of discrete geometric formulations to model two-dimensional (2-D) photonic crystals. Photonic crystals are periodic materials able to guide light by Bragg's reflection. We compared the results with an independent approach based on the multiple-scattering technique (MST). Index Terms--Discrete approaches, photonic crystals, wave propagation.

Two general strategies are introduced to identify and quantify single molecules in dilute solutions by employing a spectroscopic method for data registration and specific burst analysis, denoted multiparameter fluorescence detection (MFD). MFD uses pulsed excitation and time-correlated single-photon counting to simultaneously monitor the evolution of the eight-dimensional fluorescence information (fundamental anisotropy, fluorescence lifetime, fluorescence intensity, time, excitation spectrum, fluorescence spectrum, fluorescence quantum yield, distance between fluorophores) in real time and allows for selection of specific events for subsequent analysis. Using the multiple fluorescence dimensions, we demonstrate a dye labeling scheme of oligonucleotides, by which it is possible to identify and separate 16 different compounds in the mixture via their characteristic pattern by MFD. Such identification procedures and multiplex assays with single-molecule sensitivity may have a great impact on screening of species and events that do not lend themselves so easily to amplification, such as disease-specific proteins and their interactions.

After its introduction in 1994, LuAI[O.sub.3] :Ce (LuAP:Ce) encountered problems of 1) low light output, 2) self-absorption of scintillation light, 3) nonproportionality of light output versus energy, and 4) poor energy resolution, and 5) small non-uniform crystals. Studying newly available LuAP:Ce-doped and undoped crystals (from Photonic Materials), we have found that self-absorption is chiefly dependent on the host crystal structure and not on Ce doping. We examined the scintillation properties of these crystals and found 6.8 [+ or -] 0.3% energy resolution for 662 keV for 2 mm x 2 mm x 10 mm pixels. The intrinsic resolution is equal to 2.8 [+ or -] 0.4% at 2360 [+ or -] 120 phe/MeV (9800 [+ or -] 500 ph/MeV) light yield. These crystals have nonproportionality of 93 [+ or -] 4% at 16 keV and intrinsic energy resolution close to that of YAP:Ce. Fast components of the scintillation comprise only about half of the light that is emitted in 100 microseconds. Index Terms--.

The diffused electron clouds formed by X-ray photons interacting within the undepleted bulk of silicon beneath the depleted region of an X-ray charge-coupled device (CCD) are described. The events from the undepleted bulk are useful for retrieving information regarding the energy of the corresponding X-ray photon.

Several studies are conducted to explain the lifetimes and the formation of various intrinsic defect states present in various different two-dimensional photonic crystals. The change in the position of the displaced rod is shown to lead to the tuning of the lifetimes of the light for the pair states.

The lasing dynamics of single and coupled photonic crystal nanocavity array lasers fabricated in the indium gallium arsenide phosphide material system is measured. The finite difference time domain simulation including carrier gain and diffusion has shown that asynchronous lasing across the nanocavity array has extended the laser's pulse duration.

A finite-difference time-domain algorithm was applied to calculate the surface-layer magneto-optical effects of propagating and reflected light for photonic crystals of magnetic materials. The magneto-optical effect of the reflected light on the photonic band-gap range was strongly depended on the dielectric constant of the surface layer due to the localized surface mode.

The effect of the optical characteristics of photonic structures on the light guiding efficiency of the fluorescent concentrators is examined. An analytical model has shown that with a real photonic structure the loss cone losses are reduced by more than 75%.

Simple bottom-up self-assembly strategies are described for the synthesis of all-clay one-dimensional (1-D) and 3-D photonic crystals (PCs). The simple large-scale fabrication of porous photonic clay films and powders has shown their use as functional hierarchical materials in catalysis, adsorption and separation science.

The Z-scan and transient transmission measurements with 130 fs laser pulses in the near infrared region were performed to study the structure-property relationships in acceptor-substituted 3,4,5-trimethoxy chalcone derivatives. The ideal one-, two-, and effective three-photon figures of merit with ultrafast responses showed that acceptor-substituted 3,4,5-trimethoxy chalcone derivatives could find potential use in nonlinear photonic devices.

The Forster resonance energy transfer (FRET) experiments are conducted to explain the diffusion and conformational dynamics of various diffusing molecules. The pattern of colors in the photon trajectory of the discussed systems is shown to be completely dependent on their conformational dynamics.

The excitation spectroscopic studies of correlated photon emission from a thick barrier coupled quantum dot (CQD) are reported. The findings suggest that a dipole-dipole interdot interaction induces an enhancement in the intraband energy relaxation.

Two-photon absorption polymerization is used for fabricating the birefringent microstructures. The birefringence is caused by a light-driven molecular orientation of azoaromatic molecules upon excitation with an [Ar.sup.+] laser and it can be completely erased by overwriting the test spot with circularly polarized laser light or by heating the sample.

The quantum interference effects in the conduction intersubband transitions of n-doped quantum wells (QWs) are used for proposing a functional one-dimensional functional photonic band gap (PBG) structure. The phase associated with electromagnetically induced optical defects is adjusted by the control field, thus allowing the generation of tunable electromagnetically induced transmission resonances within the band gap.

A newly developed technique to attain and achieve the enhanced Raman scattering of the silicon photon models is described. The enhanced phenomenon is found to be a result of the strongly localized electromagnetic fields within the nanojets and hence can be widely used in all the areas of surface science.

The linear and nonlinear optical properties of two thiophene-based cyclic molecules are examined. Measurements of the different size ring structures revealed a 550% increase in the two-photon absorption (TPA) cross-section for the larger macrocycle, while the electronic structure calculations suggest an increase in coupling of the excited states in these systems as the ring size is increased.

The time-of-flight distributions of near-infrared photons emerging from thick scattering media is measured within a collection angle of 0.6 mrad about the incident light direction by means of a time-correlated single-photon counting apparatus endowed with

A unified discussion of the various nonlinear supercontinuum spectral broadening processes is presented, also reviewing by simulations the characteristics of supercontinuum generation in photonic crystal fiber for conditions covering the typical experiment parameter range from the femtosecond to the continuous-wave regime. The temporal and spectral characteristics of the supercontinuum are discussed, as also the intensity and phase stability properties of the supercontinuum spectra.

The finite difference time domain method is used to investigate the tunable directional coupler structures based on triangular photonic crystal lattices. It is shown that their properties depend on the orientation of the liquid crystal molecules, which could be controlled by the application of an external static electric field.

A pump experiment of two astronomical heterodyne receivers, a superconductor-insulator-superconductor (SIS) receiver at 450 GHz and a hot-electron-bolometer (HEB) receiver at 750 GHz, is described. SIS receiver noise temperatures are compared by using a conventional solid-state local oscillator (LO) and a photonic LO and in both cases, the best receiver noise temperature is found to be identical.

Photon pairs with correlated frequencies from an optical parametric system are generated by a continuous wave pump focused on a type-II nonlinear crystal with polarization entanglement. The application of the system, which could be used as a light source of wavelength division multiplexing quantum key distribution, optimizing the configuration of the photon-pair generation is proposed.

An exact analytical dispersion relation is derived for transverse-magnetic modes with [k.sub.z]=0 in a particular two-dimensional rectangular photonic band gap structure and the dispersion relation is analyzed, and the dispersion characteristics are determined. Analytical results are compared with results from the Massachusetts Institute of technology Photonic Band Gap structure simulator (PBGSS) code and error tolerance in the PBGSSV code is established.

The effect of both single-photon and two-photon absorption mechanisms on the Kerr-nonlinear behavior of resonant structures is investigated using a semianalytical, one-dimensional model. It is revealed that two-photon effects may severely degrade the ultrafast, nonlinear potential of these structures.

Electronic spectroscopy of nine benzannelated endiynes and a related fulvene was studied under one-photon and two-photon excitation conditions. The probability of two-photon absorption (TPA) increases noticeably for excitation to the higher excited states and results confirmed that lowest energy TPA in benzannelated enediynes involves different orbitals than lowest energy one-photon absorbance.

A single molecule logic gate using electronically excited states and ionization/fragmentation can take advantage of the differences in cross-sections for one and two photon absorption. Fault tolerant optically pumped half adder and full adder are discussed as applications.

Photoreduction of the microproxidase-11 Fe(super III) center is observed to occur in the immobilized samples and results in a long-lived stable reduced heme. The source of the electron resulting in reduction of the heme is proposed to originate from the silica matrix, and functionalization of silica surface is suggested to facilitate electron transfer to the heme.

A single diffractive optical element for the fabrication of the woodpile photonic crystal is proposed using holographic lithography to improve the alignment and stability of the optical setup. Detailed band-gap calculations provided a blueprint defining the geometrical parameters for the fabrication of photonic crystals through holographic lithography.

Advances in condensed-matter theory have revealed that new and exotic phases of matter can exist in spin models via a simple physical mechanism, known as 'string-net condensation. This structure has the unusual property that its collective modes are gauge bosons (photons) and fermions (electrons).

As possible substrates for one-photon infrared-pumped reaction (IRPR), the structures and decomposition paths of complexes between A1H4- and three proton donors, H2O, HF, and HC1 were studied using initio methods. Analysis of the dynamics in terms of complex's normal modes indicates that the excitation in the reaction-relevant modes remains localized on a time scale greater than 1ps.

Efficient single-photon and multiphoton induced fluorescence resonance energy transfer (FRET) between donor two-photon absorbing chromophore (TPAC) moieties and a nile red acceptor chromophore in the novel dendrimers is demonstrated. A synthesis of these dendritic energy-harvesting systems and the results of the relevant absorption, single-photon, and multiphoton fluorescence experiments are detailed.

The experimental results that show how it is possible to grow very high aspect ratio photonic structures on p-type macroporous silicon using aprotic protophilic solvents, and how the dissolution mechanisms of this substrate allows one to engineer the final aspect of the macroporous lattice are presented and reported. The formation of photonic crystals is demonstrated by optical reflectance measurements.