Bulletin of the American Physical Society
2005 72nd Annual Meeting of the Southeastern Section of the APS
Thursday–Saturday, November 10–12, 2005; Gainesville, FL
Session FB: Condensed Matter IV: Optical Properties of Solids |
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Chair: Art Hebard, University of Florida Room: Hilton Hawthorne |
Friday, November 11, 2005 8:30AM - 8:42AM |
FB.00001: Investigation of Thermal Effects in High Average Power Chirped Pulse Amplifiers Vidya Ramanathan, Jinho Lee, Shengbo Xu, Xiaoming Wang, David Reitze High average power ultrafast chirped pulse amplifiers [1] have important applications for high brightness extreme ultraviolet sources and x-ray sources and for applications in materials processing. We have developed a Ti:sapphire regenerative chirped pulse amplifier system capable of producing 5W of amplified output power at repetition rates that can be varied from 5-10 kHz. High pump powers (in excess of 50 W) are required to achieve amplification factors of 10$^{6}$ and higher, resulting in significant heating of the crystal and concomitant thermal effects, such as thermal lensing, and thermal birefringence. A detailed characterization of these detrimental thermal effects on the mode profile, optical spectrum, and will be discussed along with measures undertaken to improve the amplifier's overall performance, including cryogenic cooling of the Ti-sapphire crystal, finite element analysis of the heating, thermal compensation based on negative temperature derivatives of the index of refraction, and cavity stability analysis.\newline \newline [1] S. Backus, et.al., Opt. Lett. \textbf{26}, 465 (2001). [Preview Abstract] |
Friday, November 11, 2005 8:42AM - 8:54AM |
FB.00002: Modeling of Pulse Compression in Dispersion-flattened Fibers Shengbo Xu, David Reitze Microstructured photonic crystal fibers (PCFs) have unique and tailorable properties which lead to novel ways of generating and investigating nonlinear optical phenomena. Supercontinuum generation in PCFs provide a novel way to perform pulse compression. Previous results show supercontinuum generation in PCFs is extremely sensitive to input power fluctuations. However, the chromatic dispersion of PCFs can be altered, in particular flattened, using specific fiber geometries to minimize this effect and provide stable and smooth continuum. We develop a full, extended NLSE model to simulate continuum generation in the dispersion-flattened fibers. The continuum generation is suppressed in favor of self-phase modulation and self-steepening, thus producing a cleaner spectral phase. A simulated pulse shaper using SLM is used to perform pulse compression and generating $\sim $3fs compressed pulses. Therefore, dispersion-flattened may have important application in generating single cycle ultrafast pulses. [Preview Abstract] |
Friday, November 11, 2005 8:54AM - 9:06AM |
FB.00003: Dependence of the transmission of sub-wavelength hole arrays in silver films on incident angle and light polarization Kwangje Woo, Sinan Selcuk, Arthur F. Hebard, David B. Tanner It is known that the intensity of light transmitted through an array of holes that are of sub-wavelength scale can be surprisingly high at certain wavelengths. The enhanced transmission is attributed to a coupling of surface plasmons on the two sides of the film or to diffracted evanescent waves. We have studied the systematics of this transmission using a variety of hole arrays in silver films. We have studied the transmittance as a function of the angle of incidence of the light and the polarization and found a very strong dependence of the transmission on this angle and a rather strong polarization dependence. [Preview Abstract] |
Friday, November 11, 2005 9:06AM - 9:18AM |
FB.00004: Optical transmission through metallic bilayers with subwavelength apertures Zsolt Marcet, Kwangje Woo, David Tanner, Dastin Carr, Ho Bun Chan The optical transmission through a periodical array of subwavelength apertures in a metal film can be strongly enhanced by resonance of the incident light with surface plasmon polaritons and/or diffracted evanescent waves. The excitation of surface waves is accompanied by a dramatic enhancement of the local electromagnetic field on the metal surfaces. We have fabricated subwavelength structures consisting of two layers of metal. The metal layers are positioned sufficiently close to each other such that the evanescent fields of the surface plasmons generated in the first layer excite surface plasmons in the second layer. In some cases the two metal layers are laterally displaced such that no direct line of sight exists through the structure. Nevertheless, the transmission through a number of these devices remains remarkably high at resonance, comparable to the single layer value. We will discuss the dependence of the optical transmission on various sample parameters, including metal layer thickness, separation, lateral shift and incident angle of light. [Preview Abstract] |
Friday, November 11, 2005 9:18AM - 9:30AM |
FB.00005: Magneto-Optical Scattering from Nanometer-Scale Particles Kevin Stokes, Damon Smith We present calculations of the magneto-optical properties of magnetic particles with nanometer-scale dimensions. The scattering is calculated with the discrete dipole approximation (DDA). The DDA is a finite element approximation in which the particle is divided into a regular grid of radiating dipoles with grid spacing much smaller than the wavelength of incident radiation. The implementation of this approximation for gyrotropic (magneto-optical) media is discussed as well as the interpretation of the calculated scattering matrix. Calculations are performed for spherical particles, wires and collections of interacting particles. We also present experimental Faraday rotation spectra of magnetite nanoparticles in a polymer matrix. The data show a red shift of particular spectral features as a function of particle concentration. This is shown to be qualitatively consistent with model calculations which include interparticle interactions. [Preview Abstract] |
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