Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session X29: Photonics Applications |
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Sponsoring Units: FIAP Chair: Hans-Peter Wagner, University of Cincinnatti Room: C123 |
Thursday, March 18, 2010 2:30PM - 2:42PM |
X29.00001: Study the orbital rotation of a trapped metal micro-particle driven by focusing circularly polarized beam Yiqiong Zhao, Daniel T. Chiu, David Mcgloin, David Shapiro It is well know that matter can absorb the angular momentum (AM) transfer from photons and rotate around particular axis. Normally, spin rotation around sample's own axis is driven by absorbing spin AM of circularly polarized light, while absorbing orbital AM of light with spiral phase would drive orbital rotation around the beam axis. In this presentation, we study the orbital rotation which is particularly driven by focusing circularly polarized Gaussian beam. A micron-sized gold particle, which was trapped off-axis several microns below focus, was used as a micro-detector to absorb the orbital AM transferred from light and orbited around the beam axis. The experiments showed that the direction of orbital motion was in accordance with the handedness of the circular polarization. The orbiting dynamic of the trapped particle were quantitatively measured and discussed as a function of the laser power, numerical aperture of lens and particle size. [Preview Abstract] |
Thursday, March 18, 2010 2:42PM - 2:54PM |
X29.00002: Nanoprobes with optical tweezers for biological applications Mark Kendrick, David McIntyre, Oksana Ostroverkhova, Valeriya Bychkova, Alexey Shvarev We explore the use of sub-micron sized particles in optical tweezer traps as nanoprobes in microfluidic devices and biological cells. For applications that require high spatial resolution, the ability to suppress the particle's natural Brownian motion down to the nanometer or sub-nanometer scales is essential. However, the optical tweezer force scales with the volume of the particle making it difficult to confine and manipulate nanometer sized particles with high precision. To overcome this difficulty, we explore the possibility of using optically resonant particles as nanoprobes. The resonant particles should experience an increase in the optical tweezer force at wavelengths on the red side of the absorption resonance, resulting in a tighter confinement. We explore this phenomenon by measuring the trapping force acting on resonant particles (dye-filled polymeric and metallic particles) as a function of trapping laser wavelength and discuss the feasibility of using them as a high spatial resolution probe. In addition, we use similar particles as optically trapped nanoprobes to monitor temporal and spatial differences in an inhomogeneous environment; for example, we have developed pH-sensitive fluorescent nanoprobes for biological applications. [Preview Abstract] |
Thursday, March 18, 2010 2:54PM - 3:06PM |
X29.00003: Nanobeacons: Far-field-radiating nanoscale optical waveguides Pashupati Dhakal, Yun Peng, G. McMahon, K. Kempa, M.J. Naughton Some of us have recently demonstrated that visible light can be transmitted through coaxial waveguides having subwavelength transverse dimensions [1]. Here, we used focused ion beam-assisted (FIB) deposition to precisely position and fabricate vertical nanopillars that will function as inner conductors of nanocoaxial optical waveguides. The coax annuli were prepared by atomic layer deposition of a 100 nm thick conformal oxide coating, with sputtered metal used for the outer electrodes. Using high resolution optical microscopy, we successfully demonstrated the transmission of visible light into, along and out of these subwavelength nanocoaxes prepared by this \textit{in situ} FIB method. The macroscopic distance between the coax termini and the detecting microscope confirms that the nanocoaxes are functioning as ``nanobeacons'', radiating \textit{far-field} light.\\[4pt][1] J. Rybczynski, K. Kempa, A. Herczynski, Y. Wang, M.J. Naughton, Z.F. Ren, Z.P. Huang, D. Cai, and M. Giersig, Appl. Phys. Lett. 90, 021104 (2007). [Preview Abstract] |
Thursday, March 18, 2010 3:06PM - 3:18PM |
X29.00004: Optoelectronic metamaterials for sub-wavelength imaging in the mid infra red regime Mahesh Krishnamurthi, Justin Sparks, Neil Baril, Rongrui He, Pier Sazio, John Badding, Venkatraman Gopalan The mid infrared (MIR) wavelength range of 4-10$\mu $m is critically important to various technologies such as sensing, night vision, nondestructive testing, human health, and scientific research. We have developed a sub-wavelength imaging system in the MIR. The fabrication is based on the high-pressure chemical fluid deposition platform developed in our laboratories to create periodic arrays of waveguides inside the holes of a silica based microstructured optical fiber. Waveguides fabricated within each of these holes, acts as a pixel in the infra red camera. The waveguides in each of the holes of the microstructured optical fiber are tapered down to sub-wavelength dimensions at the input plane. Tapering the microstructured optical fiber down to sub-wavelength dimensions will enable sub-wavelength resolution and, also magnify the image at the output plane. The magnification at the output plane also helps in using the commercially available imaging systems to record the information. The details of numerical modeling, fabrication scheme and characterization of the infrared camera will be discussed. Basic essential features such as optical isolation, magnification and elementary imaging concepts will be presented. In addition, design variations that can be adopted to improve the resolution of the camera will be discussed. [Preview Abstract] |
Thursday, March 18, 2010 3:18PM - 3:30PM |
X29.00005: Vertical collimation of optical antenna coupled quantum dot emission Young Chul Jun We present our optical measurement results on semiconductor quantum dot (QD) emission in metal slit-groove structures. First, we show that the lifetime and polarization of QD emission in metal nanoslits are strongly modified due to surface plasmon coupling of QD emission. As a slit width gets smaller, the QD exciton lifetime gradually decreases, and its emission becomes polarized normal to the slit, as expected for plasmon coupled light emission. Its out-coupled light can be also collimated vertically into a narrow angle with optimized side grooves. We experimentally demonstrate and visualize this vertical beaming, using a confocal scanning of QD emission. Our metal slit-groove structure works as an optical antenna, sourced by QD in the center nanoslit. These experimental demonstrations may open the door to novel applications in spectroscopy, sensing, and optoelectronic devices. [Preview Abstract] |
Thursday, March 18, 2010 3:30PM - 3:42PM |
X29.00006: Optical Resonant Cavities in Volume Bragg Gratings Sergiy Mokhov, Leonid Glebov, Julien Lumeau, Vadim Smirnov, Boris Zeldovich We propose narrow-band filter in volume Bragg grating (VBG) with bandwidth less than ten picometers. Two recorded Bragg gratings with the same modulation amplitudes and slightly different resonant wavelengths form moir\'{e} pattern with average carrier spatial frequency and slowly varying envelope of modulation amplitude. Each semi-period of modulation is just apodized reflective VBG; however two of them together form narrow-band transmission Fabry-Perot cavity due to phase $\pi $-shift as result of sign change of slowly varying envelope. We fabricated first moir\'{e} VBG filter in photo-thermo-refractive glass with resonance wavelength near 1550 nm, aperture size 5 mm, bandwidth 50 pm and 95{\%} maximum transmittance. We considered also case when carrier Bragg grating wave vector does not coincide with moir\'{e} pattern wave vector which allows creating filters with tunable one-period envelope profile from sinusoidal function to cosinusoidal one. Doubled resonant cavity with cosinusoidal profile demonstrates flattop transmission peak. Analytical expression for tunable bandwidth was found. Robust solid-state moir\'{e} VBG filters tolerant to high-power laser irradiation with tunable filtering characteristics are suggested as optical elements for laser design and spectroscopy applications. [Preview Abstract] |
Thursday, March 18, 2010 3:42PM - 3:54PM |
X29.00007: Fabrication and Characterization of Porous Alumina Template based Gold-Polymer Nanocomposite Plasmonic Nanoarrays Shobha Shukla, K.T. Kim, A. Baev, Y.K. Yoon, P.N. Prasad Plasmonic nanostructures can be tuned by changing their geometry such as the aspect ratio of gold pillars. Although they are very attractive for many applications such as biosensors, imaging beyond diffraction limit etc. there is lack of an easy, cost-effective process for implementing such structures. We report a simple, facile and manufacturable method to produce gold-polymer plasmonic nanoarrays in nanoporous alumina templates. Two dimensional arrays of gold-polymer nanocomposite support discrete plasmon resonance modes at visible and infrared frequencies. Finite element full-wave analysis in three-dimensional computational domain confirms our experimental results. [Preview Abstract] |
Thursday, March 18, 2010 3:54PM - 4:06PM |
X29.00008: Real-time 3D holographic imaging using phase coherent photorefractive quantum wells Amit Dongol, Amin Kabir, Xiaosheng Wang, Hans Peter Wagner Photorefractive semiconductor quantum wells (QWs) are ideal dynamic holographic films for optical coherence imaging (OCI) because of their high diffraction efficiency and fast response time. Recently, we discovered a phase coherent photorefractive (PCP) effect in ZnSe QWs which utilizes the coherence of excitons for time gating. This new quality enables ``single-shot'' three-dimensional (3D) OCI in which the depth of an object is determined from the brightness profile of its holographic image. The short refresh time ($\sim $10 microseconds) of the PCP effect therefore allows real-time video acquisition of moving objects with a depth resolution of a few micrometers. We present real-time and depth-resolved OCI of moving glass beads of $\sim $100 micrometer size in solution using 90 fs laser pulses. Our measurements demonstrate the potential of the PCP effect for studying 3D diffusion and aggregation of micro objects that are dispersed in soft materials. [Preview Abstract] |
Thursday, March 18, 2010 4:06PM - 4:18PM |
X29.00009: GaP Photonic Crystal Microcavities for Coupling to Nitrogen-Vacancy Centers in Diamond Jenna Hagemeier, Susanna Thon, Hyochul Kim, Dirk Bouwmeester, Ronald Hanson, Toeno van der Sar, Wolfgang Pfaff, Tjerk Oosterkamp Nitrogen-Vacancy (NV) centers in diamond have been studied as single quantum emitters for applications in quantum optics and quantum information. We discuss the possibility of coupling single NV centers in diamond nanocrystals to GaP photonic crystal (PC) microcavities. Fabrication of PC microcavities in GaP, with quality factors of up to 5000, will be presented, as well as methods for characterizing bare cavities using optical fiber tapers. Positioning of diamond nanocrystals containing single NV centers for coupling to the optical mode of a PC device will also be discussed. [Preview Abstract] |
Thursday, March 18, 2010 4:18PM - 4:30PM |
X29.00010: Rapid Polarization Activity in Optical Communication Systems David Yevick, Michael Reimer, George Soliman We have recently analyzed the high-speed polarization and polarization-mode-dispersion (PMD) transients associated with mechanical impacts on a dispersion compensation module consisting of several km of optical fiber. These generate in our experiments rotational frequencies of up to several hundred radians/sec on the Poincare sphere that can severely degrade the performance of both standard and non-conventional communications systems. Accordingly, we implemented several procedures for performing high-speed polarization measurements, employed these to analyze small and large amplitude excitations and compared the results with a heuristic fiber model. Theoretically, we extended our previous work on applying the Magnus expansion to the analysis of the dependence of the PMD and polarization-dependent-loss (PDL) on frequency. From these, we obtained simple procedures for modeling polarization behavior over a wide frequency range from a small number of experimental measurements. Finally, we analyzed the applicability of various models of stochastic time-dependent refractive index variations to system outage prediction. [Preview Abstract] |
Thursday, March 18, 2010 4:30PM - 4:42PM |
X29.00011: Manipulation of temperature dependence of photothermal response in metal nanoparticles by wavelength detuning S.N. Wani, L. Yang, R. Sureshkumar We investigate the temperature dependence of the absorption cross-section of an ideal Drude like metal, Au and Ag nanoparticles. We show that when Au or Ag nanoparticles held on a SiO$_{2}$ substrate are irradiated at the resonance wavelength (at the reference temperature), model predictions for the steady-state temperature can differ substantially from that obtained by treating the absorption cross-section to be temperature independent. Red-shifting of the laser wavelength from the resonance can lead to a monotonic increase in absorption cross-section with near linear increase in the temperature. Potential applications of such photothermal behavior will be discussed. [Preview Abstract] |
Thursday, March 18, 2010 4:42PM - 4:54PM |
X29.00012: Plasmon-polariton band structures of asymmetric T-shaped plasmonic gratings Mohammed Abbas, Yia-Chung Chang, Min-Hsiung Shih It is shown that asymmetric T-shaped plasmonic gratings can display plasmon-polariton band structures with wide range of band gaps and tunable group velocities. A structure gap is introduced in the post of T-shaped plasmonic gratings and it is found that the size of this gap plays an important role in controlling the plasmon-polariton band gap and group velocities. We obtained variation of energy band gap ranging from 0.4eV to 0.0323eV by changing the size of the gap inside the structure from 0 to 250nm. The plasmon-polariton band structures were obtained by using Rigorous Coupled Wave Analysis (RCWA). We have studied the momentum gap in the photonic band structure. In this device, we obtain tunable group velocities ranging from one to several orders of magnitude smaller than the speed of light in the vacuum. This asymmetric T-shaped plasmonic grating is expected to have applications in surface plasmon polariton (SPP) based optical devices, such as filters, waveguides, splitters and lasers, especially for applications requiring large photonic band gap. [Preview Abstract] |
Thursday, March 18, 2010 4:54PM - 5:06PM |
X29.00013: Experimental observation of THz generation due to Cherenkov Radiation coupled with Phonon-Polariton in Subluminal regime Chien-Ming Tu, Ju-Chun Huang, Jeng-Chung Chen, Cheng-Chung Chi We report an experimental study of the wave form of the THz radiation generated by $<$110$>$ ZnTe crystal illuminated with ultrafast optical pulses. The co-linearly measured wave from consists of a main THz pulse due to the electro-optical effect and a trailing quasi monochromatic oscillations, with duration at least 42 ps. We have also mapped out a two-dimension radiation profile along the direction parallel to the polarization. As the probe beam moves away from the center position, the amplitude of the main THz pulse reduces much slower than that of the trailing oscillations. The experimental observations agree very well with the theoretical predictions by M. I. Bakunov et al. (PRB 76, 085346 (2007)). Their theory is based on the Cherenkov radiation in subluminal regime within the crystal. The quasi monochromatic oscillations are the result from the phase matching condition between the THz pulse and the coherent phonon-polariton generated by the optical pulses. By virtue of good fitting, we clearly demonstrate the origin of this intriguing THz wave form. [Preview Abstract] |
Thursday, March 18, 2010 5:06PM - 5:18PM |
X29.00014: Plasmonic Coupled Cavities on Moire Surfaces Sinan Balci, Askin Kocabas, Mustafa Karabiyik, Coskun Kocabas, Atilla Aydinli We investigate surface plasmon polariton (SPP) coupled cavity modes on Moire surfaces. An experimental study has been made of the propagation of SPPs on a thin silver surface that is textured with Moire surface pattern using interference lithography. The Moire surface contains periodic array of one dimensional cavities. The distance between the cavities can be controlled by changing the periodicities of Moire surface. When the SPP cavity separation is sufficiently small, we show splitting of strongly coupled plasmonic cavity modes through numerical simulations. Conversely, when the SPP cavity separation is sufficiently large, SPP cavity modes are found to be localized and do not show splitting of SPP cavity modes . This splitting of SPP cavity modes are well explained with a tight binding model that has been succesfully applied in photonic coupled cavities. Reflection measurements and numerical simulation of a large number of adjacent SPP cavities have shown a coupled resonator optical waveguide (CROW) type plasmonic waveguide band formation within the band gap region of unperturbed uniform grating. [Preview Abstract] |
Thursday, March 18, 2010 5:18PM - 5:30PM |
X29.00015: Grating Loaded Cantilevers for Displacement Measurements Ertugrul Karademir, Selim Olcum, Abdullah Atalar, Atilla Aydinli A cantilever with a grating coupler engraved on its tip is used for measuring displacement. The coupled light in the cantilever is guided to a single mode optical waveguide defined at the base of the cantilever. The grating period is 550 nm and is fabricated on a SOI wafer using nanoimprint lithography. The waveguide and the cantilever are defined by an RIE and cantilevers released by KOH and HF solutions. Light with 1550 nm wavelength, is directed onto the grating coupler and detected at the cleaved end of the SOI waveguide. The angle of incidence is controlled by a motorized rotary stage. Light couples into the waveguide at a characteristic angle with a full width at half maximum of approximately 6.9 mrads translating into a Q factor of 87.5. The displacement sensitivity is measured by driving the cantilever with a frequency controlled piezoelectric element. The modulation of the light at the waveguide output is lock-in detected by a biased infrared detector. The resulting 43{\%}mrad$^{-1}$ sensitivity can be increased with further optimization. [Preview Abstract] |
Thursday, March 18, 2010 5:30PM - 5:42PM |
X29.00016: Frequency Shift of Polar Whispering Gallery Modes Caused by Uniaxial Stress H. -P. Wagner, H. Schmitzer, J. Lutti, P. Borri, W. Langbein Optical whispering gallery modes in small spheres -so called microcavity optical resonators- have been investigated in the past years because they are promising as single virus or single bacterium detectors and as pressure sensors for microfluidic applications. Due to high Q-factors whispering gallery modes are very sensitive to changes of the shape and the refractive index of the sphere. Both can be caused by mechanical stress. A small exerted compressive force will therefore lead to an energy shift of the resonant modes. The relationship between this energy shift and the exerted force depends on the geometry of the experimental setup. We investigated the energy shift of polar modes in polystyrene beads of 45 micron diameter applying an uniaxial force. With increasing force we find a shift to higher energy for resonator modes with different mode order $n$ and number $l$. The observed results will be compared with model calculations. [Preview Abstract] |
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