Optics Commons^™

Photonic Band Gap Analysis Using Finite-Difference Frequency-Domain Method, Shangping Guo, Feng Wu, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

A finite-difference frequency-domain (FDFD) method is applied for photonic band gap calculations. The Maxwell’s equations under generalized coordinates are solved for both orthogonal and non-orthogonal lattice geometries. Complete and accurate band gap information is obtained by using this FDFD approach. Numerical results for 2D TE/TM modes in square and triangular lattices are in excellent agreements with results from plane wave method (PWM). The accuracy, convergence and computation time of this method are also discussed.

Speed-Up Collisions In Strong-Field Double Ionization, Stanley L. Haan, J. C. Cully, K. Hoekema

University Faculty Publications and Creative Works

We compare quantum and classical models of double ionization (DI) for aligned-electron helium in strong laser fields, considering specifically the role of recollision processes in which the returning electron travels in the direction of the laser force. Quantum studies show that for the knee region in our model a small but persistent portion of the total DI occurs through these speed-up collisions. We show that classical modeling displays similar collisions and reveals that with-the-force doubly ionizing collisions typically involve two-particle trajectories in which both electrons can be said to have been bound or very nearly bound at the zero of …

Comparative Analysis Of Bragg Fibers, Shangping Guo, Sacharia Albin, Robert S. Rogowski

Electrical & Computer Engineering Faculty Publications

In this paper, we compare three analysis methods for Bragg fibers, viz. the transfer matrix method, the asymptotic method and the Galerkin method. We also show that with minor modifications, the transfer matrix method is able to calculate exactly the leakage loss of Bragg fibers due to a finite number of H/L layers. This approach is more straightforward than the commonly used Chew’s method. It is shown that the asymptotic approximation condition should be satisfied in order to get accurate results. The TE and TM modes, and the band gap structures are analyzed using Galerkin method.

Loss And Dispersion Analysis Of Microstructured Fibers By Finite-Difference Method, Shangping Guo, Feng Wu, Sacharia Albin, Hsiang Tai, Robert S. Rogowski

Electrical & Computer Engineering Faculty Publications

The dispersion and loss in microstructured fibers are studied using a full-vectorial compact-2D finite-difference method in frequency-domain. This method solves a standard eigen-value problem from the Maxwell’s equations directly and obtains complex propagation constants of the modes using anisotropic perfectly matched layers. A dielectric constant averaging technique using Ampere’s law across the curved media interface is presented. Both the real and the imaginary parts of the complex propagation constant can be obtained with a high accuracy and fast convergence. Material loss, dispersion and spurious modes are also discussed.

Spatial Frequency Response Of Acrylamide Based Holographic Photopolymer, Raghavendra Jallapuram, Izabela Naydenova, Vincent Toal, Suzanne Martin, Robert Howard

Conference Papers

It has been shown that photopolymers are useful in holographic optical elements [1] and holographic interferometry [2]. However, the list of potential applications increases greatly if reflection holography is possible. Reflection holography requires a material that has the potential to record high spatial frequencies. Here we studied the spatial frequency response of an acrylamide based dye sensitized holographic photopolymer. We have investigated the effect of molecular weight of the binder and concentration of crosslinking monomer on diffusion using real time monitoring of the holographic grating formation. The effect of uniform pre-exposure on diffusion was also investigated. We have also demonstrated …

Examination Of Focused Beam Propagation Through A Finite Non-Reciprocal Planar Chiral Slab Using Complex Fresnel Coefficients And Dual Transforms, Monish Ranjan Chatterjee, Sumit Nema, Partha P. Banerjee

Electrical and Computer Engineering Faculty Publications

Recently, uniform plane wave propagation across a nonchiral-chiral interface was examined via the development of appropriate Fresnel coefficients. In this extension, propagation of focused uniform and profiled beams through a finite, planar nonreciprocal chiral slab is investigated using complex Fresnel coefficients via angular plane wave decomposition and dual transforms.

Revisiting The Fresnel Coefficients For Uniform Plane Wave Propagation Across A Nonchiral, Reciprocal And Chiral, Nonreciprocal Interface, Monish Ranjan Chatterjee, Sumit Nema

Electrical and Computer Engineering Faculty Publications

The problem of EM wave propagation in non-reciprocal chiral media has been studied by several investigators. In a recent approach, a dual-transform technique has been developed to study the problem of such propagation under paraxial and slow-envelope variation conditions.

In this paper, we first outline some of the results obtained using the dual transform technique for arbitrary boundary conditions within the left boundary of a semi-infinite, non-reciprocal chiral medium for a uniform plane wave, and a fundamental Gaussian-profiled beam. Next, we explore the problem of a uniform EM wave incident at an oblique angle at an interface between a reciprocal, …

Application Of A Photopolymer Material In Speckle Pattern Shearing Interferometry, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal

Conference Papers

A new application of a photopolymer diffractive optical element in electronic speckle pattern shearing interferometer (ESPSI) is presented. In the first stage a holographic grating is recorded using an acrylamide based photopolymer material. Since the polymerisation process occurs during recording, the holograms are produced without any development or processing. In the second stage the holographic grating is used to produce the two sheared images in an ESPSI configuration. A ground glass screen following the grating serves the purpose of eliminating unwanted diffraction orders. The distance between the grating and the ground glass can be used to control the amount of …

Theoretical Study On The Optical Properties Of Polyvinylidene Fluoride Crystal, Chun-Gang Duan, Wai-Ning Mei, Wei-Guo Yin, Jianjun Liu, J. R. Hardy, Mengjun Bai, Stephen Ducharme

Stephen Ducharme Publications

We report our first-principles studies on the linear and non-linear optical properties of ferroelectric polyvinylidene fluoride crystal. Calculated values of the refractive indices agree well with experiments. As regards the second-harmonic-generation coefficients, theoretical values are larger than experimental ones. Possible reasons for the discrepancy are discussed.

Optimal Beam Splitters For The Division-Of-Amplitude Photopolarimeter, R. M.A. Azzam, A. De

Electrical Engineering Faculty Publications

Optimal optical parameters of the beam splitter that is used in the division-of-amplitude photopolarimeter are determined. These are (1) 50%–50% split ratio of the all-dielectric beam splitter, (2) differential phase shifts in reflection and transmission Δ_r and Δ_t that differ by ±π/2, and (3) ellipsometric parameters (ψ_r, ψ_t)= (27.368°, 62.632°) or (62.632°, 27.368°). It is also shown that for any nonabsorbing beam splitter that splits incident unpolarized light equally, the relationship ψ_r+ψ_t=π/2 is always satisfied.

Monte Carlo Simulations Of Surface Phase Transitions In A Modulated Layered Structure, Da Gao, John A. Jaszczak

Department of Physics Publications

A solid-on-solid model of a layered crystal, which has five layers per repeat period in the direction normal to the surface and with only nearest-neighbor interactions, is studied using Monte Carlo simulation to investigate the relationship between crystal structure and the corresponding surface phases. Equilibrium properties, such as the surface specific heat, interface width, and autocorrelation times, are studied as a function of temperature and system size. Results indicate three distinct surface phases exist in this model: a low-temperature flat phase, an intermediate-temperature disordered but flat phase, and a high-temperature rough phase. We suggest the possibility of introducing several intermediate …

Wide Angle Achromatic Prism Beam Steering For Infrared Countermeasures Applications, Bradley D. Duncan, Philip J. Bos, Vassili Sergan

Electro-Optics and Photonics Faculty Publications

The design and analysis of achromatic doublet prisms for use in laser beam steering is presented. The geometric relationships describing the maximum steering angle are given, as are discussions of first- and second-order dispersion reduction. Infrared (IR) material alternatives and optimum IR material characteristics for wide-angle achromatic prism beam steering are also investigated. Sixteen materials in 120 different combinations have been examined to date. For midwave IR applications it is shown that the minimum dispersion currently achievable across the full 2 to 5 μm spectrum is 1.7816 mrad at an average maximum steering angle of 45 deg. This is accomplished …

Single-Mode Raman Fiber Laser In A Multimode Fiber, Matthew B. Crookston

Theses and Dissertations

The feasibility of a transverse single-mode Raman fiber laser using a multimode fiber has been investigated. The Raman fiber laser operates in low-order transverse modes despite the fact the fiber supports multimode beam propagation. The performance characteristics of the Raman fiber laser are compared with those of the single-pass SRS beam.

Optical Characterization Of Antimony-Based, Types-I And Ii, Multiple Quantum-Well Semiconductor Structures For Mid-Infrared Laser Applications, Edward G. Ferguson

Theses and Dissertations

This experiment characterizes antimony-based, multiple quantum-well, types-I and -II, semiconductor samples designed for laser applications. The samples emit light in the 3-5-micron range to exploit an atmospheric transmission window, making them ideal for infrared (IR)-seeking missile countermeasures. Photoluminescence (PL) spectra were collected and yielded bandgap (E(sub g)) dependence-on-temperature relationships. The type-I sample was found to follow the Varshni equation, while the type-II samples showed a rise with temperature in a portion of the curve that should be linear according to the Varshni equation. The type-II samples followed the Varshni equation well at higher temperature. The PL study indicated that the …

Phasing A Dual Optical Path System Using An Optical Fiber As A Phase Conjugate Mirror, Shawn M. Willis

Theses and Dissertations

Phase conjugation properties of stimulated Brillouin scattering (SBS) in a short multimode fiber have been investigated with an eye towards its application for a multi-channel double pass master oscillator power amplifier (MOPA) system. In particular, properties of the SBS beam to compensate for the axial and transverse phase distortion between individual channels in a multi-channel amplifier system were studied. Two optical paths were created by covering half of the laser beam with a microscope slide, and also by spatially splitting the wavefronts with a 4 prism set-up. The Stokes beams that traversed the same optical paths as the pump beams …

Index-Matched Boundary Techniques For The Elimination Of Acoustical Resonances, Jack H. Parker, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

We extend the principle of optical index of refraction to apply the concept of acoustical index for transverse acoustical wave propagation in strings. The relationship between acoustical index and mass density of the acoustic material is developed. With this theoretical link established, classic index-matching techniques are explored at acoustical boundaries. Proper selection of boundary interface segments leads to the elimination of resonant vibrationalmodes that occur in rigidly supported strings, while maintaining the nonresonant vibration response.

Digital Image Processing, Russell C. Hardie, Majeed M. Hayat

Electrical and Computer Engineering Faculty Publications

In recent years, digital images and digital image processing have become part of everyday life. This growth has been primarily fueled by advances in digital computers and the advent and growth of the Internet. Furthermore, commercially available digital cameras, scanners, and other equipment for acquiring, storing, and displaying digital imagery have become very inexpensive and increasingly powerful. An excellent treatment of digital images and digital image processing can be found in Ref. [1]. A digital image is simply a two-dimensional array of finite-precision numerical values called picture elements (or pixels). Thus a digital image is a spatially discrete (or discrete-space) …

Breakdown Of The Slowly Varying Amplitude Approximation: Generation Of Backward Traveling Second Harmonic Light, J. Z. Sanborn '01, C. Hellings '02, Thomas D. Donnelly

All HMC Faculty Publications and Research

By numerically solving the nonlinear field equations, we simulate second-harmonic generation by laser pulses within a nonlinear medium without making the usual slowly-varying-amplitude approximation, an approximation which may fail when laser pulses of moderate intensity or ultrashort duration are used to drive a nonlinear process. Under these conditions we show that a backward-traveling, second-harmonic wave is created, and that the magnitude of this wave is indicative of the breakdown of the slowly-varying-amplitude approximation. Conditions necessary for experimental detection of this wave are discussed.

Compact Supercell Method Based On Opposite Parity For Bragg Fibers, Wang Zhi, Ren Guobin, Lou Shuquin, Liang Weijun, Shangping Guo

Electrical & Computer Engineering Faculty Publications

The supercell- based orthonormal basis method is proposed to investigate the modal properties of the Bragg fibers. A square lattice is constructed by the whole Bragg fiber which is considered a supercell, and the periodical dielectric structure of the square lattice is decomposed using periodic functions (cosine). The modal electric field is expanded as the sum of the orthonormal set of Hermite-Gaussian basis functions based on the opposite parity of the transverse electric field. The propagation characteristics of Bragg fibers can be obtained after recasting the wave equation into an eigenvalue system. This method is implemented with very high efficiency …

Simple Plane Wave Implementation For Photonic Crystal Calculations, Shangping Guo, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

A simple implementation of plane wave method is presented for modeling photonic crystals with arbitrary shaped ‘atoms’. The Fourier transform for a single ‘atom’ is first calculated either by analytical Fourier transform or numerical FFT, then the shift property is used to obtain the Fourier transform for any arbitrary supercell consisting of a finite number of ‘atoms’. To ensure accurate results, generally, two iterating processes including the plane wave iteration and grid resolution iteration must converge. Analysis shows that using analytical Fourier transform when available can improve accuracy and avoid the grid resolution iteration. It converges to the accurate results …

Chaotic Free-Space Laser Communication Over Turbulent Channel, N. F. Rulkov, Mikhail Vorontsov, L. Illing

Electro-Optics and Photonics Faculty Publications

The dynamics of errors caused by atmospheric turbulence in a self-synchronizing chaos-based communication system that stably transmits information over a ∼5  km free-space laser link is studied experimentally. Binary information is transmitted using a chaotic sequence of short-term pulses as a carrier. The information signal slightly shifts the chaotic time position of each pulse depending on the information bit. We report the results of an experimental analysis of the atmospheric turbulence in the channel and the impact of turbulence on the bit-error-rate performance of this chaos-based communication system.

Ion Contribution To The Astrophysical Important 447.15, 587.56 And 667.82 Nm He I Spectral Lines Broadening, Vladimir Milosavljevic, Stevan Djenize

Articles

Characteristics of the astrophysical important Stark broadened 447.15 nm, 587.56 nm and 667.82 nm spectral line profiles have been measured at electron densities between 0.3 10 and 8.2 10 m and electron temperatures between 8000 and 33 000 K in plasmas created in five various discharge conditions using a linear, low-pressure, pulsed arc as an optically thin plasma source operated in a helium-nitrogen-oxygen gas mixture. On the basis of the observed asymmetry of the line profiles we have obtained their ion broadening parameters ( A) caused by influence of the ion microfield on the line broadening mechanism and also …

Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson

Electro-Optics and Photonics Faculty Publications

We present four receiver designs for a ladar system, based on an optical parametric amplifier, that is designed to collect returns from glint targets. After coupling the return energy into periodically poled lithium niobate, the target backscatter is detected with either an infrared camera or a CCD array. Assuming reasonable detector and system characteristics, the sensitivity of each design is then evaluated by setting the receiver SNR detection threshold equal to one and using the minimum transmitted energy as the figure of merit. Through numerical analysis, we show that an upconversion receiver followed by a visible CCD array offers the …

Development Of An Efficient Ti:Sapphire Laser Transmitter For Atmospheric Ozone Lidar Measurements, Khaled A. Elsayed

Electrical & Computer Engineering Theses & Dissertations

The impetus of this work was to develop an all solid-state Ti:sapphire laser transmitter to replace the current dye lasers that could provide a potentially compact, robust, and highly reliable laser transmitter for differential absorption lidar measurements of atmospheric ozone. Two compact, high-energy pulsed, and injection-seeded Ti:sapphire lasers operating at a pulse repetition frequency of 30 Hz and wavelengths of 867 nm and 900 nm, with M² of 1.3, have been experimentally demonstrated and compared to model results. The Ti:sapphire lasers have shown the required output beam quality at maximum output pulse energy, 115 mJ at 867 nm and …

Reflection-High Energy Electron Diffraction Study Of Si(100) Homoepitaxy By Femtosecond Pulsed Laser Deposition, Mohammed S. Hegazy

Electrical & Computer Engineering Theses & Dissertations

The dynamics of femtosecond pulsed laser deposition (fsPLD) of Si(!00)-1 x I and Si(!00)-2x I homoepitaxy are studied by in situ reflection high-energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM). The effects of substrate temperature, laser fluence and the pressure of a passive gas on the Si(!00)-1 x I growth mode are discussed. It is shown that films grow following the Volmer-Weber (3D) growth mode. The substrate temperature largely affects the morphology of the grown film. Below ~ 400 °C (at laser fluence of~ 1.9 J/cm²), randomly oriented 3D clusters are grown. This is shown …

Experimental Quantum Cloning Of Single Photons, Antia Lamas-Linares, Christoph Simon, John C. Howell, Dik Bouwmeester

Mathematics, Physics, and Computer Science Faculty Articles and Research

Although perfect copying of unknown quantum systems is forbidden by the laws of quantum mechanics, approximate cloning is possible. A natural way of realizing quantum cloning of photons is by stimulated emission. In this context, the fundamental quantum limit to the quality of the clones is imposed by the unavoidable presence of spontaneous emission. In our experiment, a single input photon stimulates the emission of additional photons from a source on the basis of parametric down-conversion. This leads to the production of quantum clones with near-optimal fidelity. We also demonstrate universality of the copying procedure by showing that the same …

Development Of A Tm:Ho:Ylf-Laser-Pumped Orientation-Patterned Gallium Arsenide Optical Parametric Oscillator, Michael D. Harm

Theses and Dissertations

Coherent optical sources in the mid-infrared region (mid-IR) are important fundamental tools for infrared countermeasures and battlefield remote sensing. Nonlinear optical effects can be applied to convert existing near-IR laser sources to radiate in the mid-IR. This research focused on achieving such a conversion with a quasi-phase matched optical parametric oscillators using orientation-patterned gallium arsenide (OPGaAs), a material that can be quasi-phased matched by periodically reversing the crystal structure during the epitaxial growth process. Although non-linear optical conversion was not ultimately achieved during this research, many valuable lessons were learned from working with this material. This thesis reviews the theory …

Smart Structures For Control Of Optical Surfaces, D. Michael Sobers Jr.

Theses and Dissertations

The development of lightweight, large-aperture optics is of vital importance to the Department of Defense and the US Air Force for advancing remote sensing applications and improving current capabilities. Synthetic polymer optics offer weight and flexibility advantages over current generation glass mirrors, but require active control to maintain tight surface figure tolerances. This research explores the feasibility of using imbedded piezoelectric materials to control optical surfaces. Membrane-based and stiff piezo-controlled mirrors were constructed to develop and validate control techniques. Test results verified that surface control on the order of tens of wavelengths is possible using these systems.

Distributed Beacon Requirements For Branch Point Tolerant Laser Beam Compensation In Extended Atmospheric Turbulence, Virgil E. Zetterlind Iii

Theses and Dissertations

Branch point tolerant phase reconstructors can vastly improve adaptive optic system performance in extended atmospheric turbulence. This thesis explores the performance bounds of two such reconstructors Goldstein's algorithm and hidden phase. A least squares reconstructor is implemented for comparison. System performance is presented for various scenarios, including correction time-delays, wave-front sensor noise, and extended beacons. These scenarios are of interest for laser communication and directed energy systems such as Airborne Laser. Performance bounds are obtained through wave-optics simulation. The extended beacon propagation geometry approximates the USAF AFRL-DE North Oscura Peak range. Results show that branch point tolerant reconstructors outperform least …

Fabrication Techniques For Micro-Optical Device Arrays, Ryan D. Conk

Theses and Dissertations

Micro-optical devices are vital components of conventional military data storage, sensor, and communication systems. Two types of micro-optical device arrays exist: individually addressable and matrix addressable. The matrix addressable array has a drastically reduced number of metal lines and can potentially be fabricated into large, dense (over 1k elements) arrays. Such arrays are expected to enable the development of extremely high bandwidth optical interconnect systems for future military applications including optical computing and short-haul fiber optical communication systems. I investigate new fabrication techniques for the assembly of dense matrix-addressed arrays of micro-optical devices such as vertical-cavity surface-emitting lasers. Using a …