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Sample records for diffusive optical cavity

  1. Effective optical path length for tandem diffuse cubic cavities as gas absorption cell

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gao, Q.; Zhang, Y. G.; Zhang, Z. G.; Wu, S. H.

    2014-12-01

    Tandem diffuse cubic cavities designed by connecting two single diffuse cubic-shaped cavities, A and B, with an aperture (port fraction fap) in the middle of the connecting baffle was developed as a gas absorption cell. The effective optical path length (EOPL) was evaluated by comparing the oxygen absorption signal in the cavity and in air based on tunable diode laser absorption spectroscopy (TDLAS). Experimental results manifested an enhancement of EOPL for the tandem diffuse cubic cavities as the decrease of fap and can be expressed as the sum of EOPL of two single cubic cavities at fap < 0.01, which coincided well with theoretical analysis. The simulating EOPL was smaller than experimental results at fap > 0.01, which indicated that back scattering light from cavity B to cavity A cannot be ignored at this condition.

  2. Dual frequency optical cavity

    DOEpatents

    George, E.V.; Schipper, J.F.

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a T configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  3. Dual frequency optical cavity

    DOEpatents

    George, E. Victor; Schipper, John F.

    1985-01-01

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a "T" configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  4. Optically measuring interior cavities

    SciTech Connect

    Stone, Gary Franklin

    2008-12-21

    A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.

  5. Tuned optical cavity magnetometer

    DOEpatents

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  6. Diffuse reflectivity measurement using cubic cavity.

    PubMed

    Yu, Jia; Zhang, Y G; Gao, Qiang; Hu, Gang; Zhang, Z G; Wu, S H

    2014-04-01

    A method for measuring diffuse reflectivity using cubic cavity based on the variable port fraction method was developed by measuring oxygen P11 line at 762 nm using tunable diode laser absorption spectroscopy. An experimental method to determine the additional path length l0 was presented. We measured the diffuse reflectivity of a cubic cavity with scattering coatings of different thickness. The error of diffuse reflectivity was reduced from 0.004 to 0.0003 when the diffuse reflectivity increased from 0.867(4) to 0.9887(3). A simulation result manifests that the error of diffuse reflectivity has the potential to be further reduced at higher diffuse reflectivity.

  7. Optical cavity furnace for semiconductor wafer processing

    DOEpatents

    Sopori, Bhushan L.

    2014-08-05

    An optical cavity furnace 10 having multiple optical energy sources 12 associated with an optical cavity 18 of the furnace. The multiple optical energy sources 12 may be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnace 10 may also include one or more reflectors 14 and one or more walls 16 associated with the optical energy sources 12 such that the reflectors 14 and walls 16 define the optical cavity 18. The walls 16 may have any desired configuration or shape to enhance operation of the furnace as an optical cavity 18. The optical energy sources 12 may be positioned at any location with respect to the reflectors 14 and walls defining the optical cavity. The optical cavity furnace 10 may further include a semiconductor wafer transport system 22 for transporting one or more semiconductor wafers 20 through the optical cavity.

  8. Passive optical cavity with backward scattering

    SciTech Connect

    Skryabin, D.V.; Radin, A.M.

    1994-07-01

    A passive optical cavity with an aperture is considered. An account of scattering and mode polarization results in splitting of the cavity spectrum. Analytic equations are derived for scattering losses and natural frequencies. 11 refs., 4 figs.

  9. Photonic crystal cavities and integrated optical devices

    NASA Astrophysics Data System (ADS)

    Gan, Lin; Li, ZhiYuan

    2015-11-01

    This paper gives a brief introduction to our recent works on photonic crystal (PhC) cavities and related integrated optical structures and devices. Theoretical background and numerical methods for simulation of PhC cavities are first presented. Based on the theoretical basis, two relevant quantities, the cavity mode volume and the quality factor are discussed. Then the methods of fabrication and characterization of silicon PhC slab cavities are introduced. Several types of PhC cavities are presented, such as the usual L3 missing-hole cavity, the new concept waveguide-like parallel-hetero cavity, and the low-index nanobeam cavity. The advantages and disadvantages of each type of cavity are discussed. This will help the readers to decide which type of PhC cavities to use in particular applications. Furthermore, several integrated optical devices based on PhC cavities, such as optical filters, channel-drop filters, optical switches, and optical logic gates are described in both the working principle and operation characteristics. These devices designed and realized in our group demonstrate the wide range of applications of PhC cavities and offer possible solutions to some integrated optical problems.

  10. Diffuse Optical Tomography

    NASA Astrophysics Data System (ADS)

    Yodh, Arjun

    2000-03-01

    Application of diffuse near-infrared (NIR) optical methods for imaging and spectroscopy of tissues is attractive for several reasons. The techniques utilize non-ionizing radiation, are non-invasive, and are often technologically simple and fast. The optical method also has several unique measurable parameters with potential to enhance tumor sensitivity and specificity. For example, blood dynamics, blood volume, blood oxygen saturation, and water content are often substantially different in the rapidly growing tumor, and will alter tissue optical absorption coefficients. An increase in organelle population, particularly mitochondria, accompanies the higher metabolic activity of the rapidly growing tumor, and leads to an increasing scattering coefficient for the tumor. Similarly the optical absorption, fluorescence, and scattering of contrast agents such as Indocyanine green (ICG) that occupy vascular and extravascular space provide useful forms of sensitization. In this paper I will discuss our work exploring the tumor contrasts accessible to the diffuse optical method, and I will describe how we extract this optical information using state-of-the-art theoretical, computational, and experimental technologies.

  11. Instrumentation in Diffuse Optical Imaging

    PubMed Central

    Zhang, Xiaofeng

    2014-01-01

    Diffuse optical imaging is highly versatile and has a very broad range of applications in biology and medicine. It covers diffuse optical tomography, fluorescence diffuse optical tomography, bioluminescence, and a number of other new imaging methods. These methods of diffuse optical imaging have diversified instrument configurations but share the same core physical principle – light propagation in highly diffusive media, i.e., the biological tissue. In this review, the author summarizes the latest development in instrumentation and methodology available to diffuse optical imaging in terms of system architecture, light source, photo-detection, spectral separation, signal modulation, and lastly imaging contrast. PMID:24860804

  12. Cavity-enhanced spectroscopy in optical fibers.

    PubMed

    Gupta, Manish; Jiao, Hong; O'Keefe, Anthony

    2002-11-01

    Cavity-enhanced methods have been extended to fiber optics by use of fiber Bragg gratings (FBGs) as reflectors. High-finesse fiber cavities were fabricated from FBGs made in both germanium/boron-co-doped photosensitive fiber and hydrogen-loaded Corning SMF-28 fiber. Optical losses in these cavities were determined from the measured Fabry-Perot transmission spectra and cavity ring-down spectroscopy. For a 10-m-long single-mode fiber cavity, ring-down times in excess of 2 ms were observed at 1563.6 nm, and individual laser pulses were resolved. An evanescent-wave access block was produced within a fiber cavity, and an enhanced sensitivity to optical loss was observed as the external medium's refractive index was altered.

  13. Modes of a rotating astigmatic optical cavity

    NASA Astrophysics Data System (ADS)

    Habraken, Steven J. M.; Nienhuis, Gerard

    2008-05-01

    We generalize the concept of an optical cavity mode to the case of an astigmatic cavity that rotates about its optical axis. We show that the modes of such a cavity are both spatially and spectrally confined and use an algebraic method to study their spatial and spectral structure. Our method involves ladder operators in the spirit of the quantum-mechanical harmonic oscillator. It hinges upon their algebraic properties as well as on the group-theoretical properties of the ray (ABCD) matrix that describes the time-dependent ray dynamics of the rotating cavity.

  14. Mounting system for optical frequency reference cavities

    NASA Technical Reports Server (NTRS)

    Notcutt, Mark (Inventor); Hall, John L. (Inventor); Ma, Long-Sheng (Inventor)

    2008-01-01

    A technique for reducing the vibration sensitivity of laser-stabilizing optical reference cavities is based upon an improved design and mounting method for the cavity, wherein the cavity is mounted vertically. It is suspended at one plane, around the spacer cylinder, equidistant from the mirror ends of the cavity. The suspension element is a collar of an extremely low thermal expansion coefficient material, which surrounds the spacer cylinder and contacts it uniformly. Once the collar has been properly located, it is cemented in place so that the spacer cylinder is uniformly supported and does not have to be squeezed at all. The collar also includes a number of cavities partially bored into its lower flat surface, around the axial bore. These cavities are support points, into which mounting base pins will be inserted. Hence the collar is supported at a minimum of three points.

  15. Calculating model of light transmission efficiency of diffusers attached to a lighting cavity.

    PubMed

    Sun, Ching-Cherng; Chien, Wei-Ting; Moreno, Ivan; Hsieh, Chih-To; Lin, Mo-Cha; Hsiao, Shu-Li; Lee, Xuan-Hao

    2010-03-15

    A lighting cavity is a reflecting box with light sources inside. Its exit side is covered with a diffuser plate to mix and distribute light, which addresses a key issue of luminaires, display backlights, and other illumination systems. We derive a simple but precise formula for the optical efficiency of diffuser plates attached to a light cavity. We overcome the complexity of the scattering theory and the difficulty of the multiple calculations involved, by carrying out the calculation with a single ray of light that statistically represents all the scattered rays. We constructed and tested several optical cavities using light-emitting diodes, bulk-scattering diffusers, white scatter sheets, and silver coatings. All measurements are in good agreement with predictions from our optical model.

  16. Atom interferometry in an optical cavity.

    PubMed

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-13

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100  μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75% contrast and measure the acceleration due to gravity, g, to 60  μg/sqrt[Hz] resolution in a Mach-Zehnder geometry. We use >10(7) cesium atoms in the compact mode volume (600  μm 1/e(2) waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.

  17. Atom Interferometry in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M.; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-01

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100 μ W ), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75 % contrast and measure the acceleration due to gravity, g , to 60 μ g /√{Hz } resolution in a Mach-Zehnder geometry. We use >107 cesium atoms in the compact mode volume (600 μ m 1 /e2 waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.

  18. Light diffusing fiber optic chamber

    DOEpatents

    Maitland, Duncan J.

    2002-01-01

    A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

  19. Optical Resonant Cavity in a Nanotaper

    SciTech Connect

    Lee, Sang Hyun; Goto, Takenari; Miyazaki, Hiroshi; Chang, Jiho; Yao, Takafumi

    2010-01-01

    The present study describes an optical resonant cavity in a nanotaper with scale reduction from micro to several nanometers. Both experimental results and a finite-difference time-domain (FDTD)-based simulation suggested that the nanometer-scale taper with a diameter similar to the wavelength of light acted as a mirror, which facilitated the formation of a laser cavity and caused lasing in ZnO nanotapers. As the light inside the nanotaper propagated toward the apex, the lateral mode was reduced and reflection occurred. This report suggests that use of the resonant optical cavities in nanotapers might result in novel active and passive optical components, which will broaden the horizons of photonic technology.

  20. 850-nm Zn-diffusion vertical-cavity surface-emitting lasers with with oxide-relief structure for high-speed and energy-efficient optical interconnects from very-short to medium (2km) reaches

    NASA Astrophysics Data System (ADS)

    Shi, Jin-Wei; Wei, Chia-Chien; Chen, Jason (Jyehong); Yang, Ying-Jay

    2015-03-01

    High-speed and "green" ~850 nm vertical-cavity surface-emitting lasers (VCSELs) have lately attracted lots of attention due to their suitability for applications in optical interconnects (OIs). To further enhance the speed and its maximum allowable linking distance of VCSELs are two major trends to meet the requirement of OI in next generation data centers. Recently, by use of the advanced 850 nm VCSEL technique, data rate as high as 64 Gbit/sec over 57m and 20 Gbit/sec over 2km MMF transmission have been demonstrated, respectively. Here, we will review our recent work about 850 nm Zn-diffusion VCSELs with oxide-relief apertures to further enhance the above-mentioned performances. By using Zn-diffusion, we can not only reduce the device resistance but also manipulate the number of optical modes to benefit transmission. Combing such device, which has excellent single-mode (SMSR >30 dB) and high-power (~7mW) performance, with advanced modulation format (OFDM), record-high bit-rate-distance-product through MMF (2.3 km×28 Gbit/sec) has been demonstrated. Furthermore, by selective etching away the oxide aperture inside Zn-diffusion VCSEL, significant enhancement of device speed, D-factor, and reliability can be observed. With such unique VCSEL structure, >40 Gbit/sec energy-efficient transmission over 100m MMF under extremely low-driving current density (<10kA/cm2) has been successfully demonstrated.

  1. Gas Diffusion Studies in Steady and Nonsteady Cavities

    DTIC Science & Technology

    1987-09-01

    gaseous diffusion, turbulent entrainment, cavitating flows, gas-liquid interface, two-dimensional flows, hydrofoil I Ioscillation 19 ABSTRACT...PAS Water tunnel experiments for twoidimensional f ows were co2ducted on cavities behind a stationary and oscillating -~flat plate’ (wedge) hydrofoil ...for two-dimensional flows were conducted on cavities behind a stationary and oscillating "flat plate" (wedge) hydrofoil . It is found that the steady

  2. Atom interferometry in an optical cavity

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul; Jaffe, Matt; Brown, Justin; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2014-05-01

    We have demonstrated the first light pulse atom interferometer using an in-vacuum optical cavity to generate the matter wave beamsplitters. An optical cavity allows for a compact setup with several advantages over traditional atom interferometers. Even with modest laser power, large intracavity intensity should enable high order multiphoton beamsplitters which increase the sensitivity of an interferometer. Clean wavefronts from spatial mode filtering can reduce contrast loss for both light pulse interferometers as well as optical lattice based interferometers. In addition, well-defined spatial modes allow many useful properties such as the beam size, waist position, and divergence to be determined with high accuracy. Finally, the use of high order transverse spatial modes gives multiple self-aligned beams useful in applications such as Sagnac interferometry for rotation sensing. We discuss our recent investigations into novel beamsplitters and interferometer geometries in the optical cavity and the implications for a compact inertial sensor as well as measurements of the gravitational Aharanov-Bohm effect and Newton's gravitational constant.

  3. Harnessing the mode mixing in optical fiber-tip cavities

    NASA Astrophysics Data System (ADS)

    Podoliak, Nina; Takahashi, Hiroki; Keller, Matthias; Horak, Peter

    2017-04-01

    We present a systematic numerical study of Fabry-Pérot optical cavities with Gaussian-shape mirrors formed between tips of optical fibers. Such cavities can be fabricated by laser machining of fiber tips and are promising systems for achieving strong coupling between atomic particles and an optical field as required for quantum information applications. Using a mode mixing matrix method, we analyze the cavity optical eigenmodes and corresponding losses depending on a range of cavity-shape parameters, such as mirror radius of curvature, indentation depth and cavity length. The Gaussian shape of the mirrors causes mixing of optical modes in the cavity. We investigate the effect of the mode mixing on the coherent atom-cavity coupling as well as the mode matching between the cavity and a single-mode optical fiber. While the mode mixing is associated with increased cavity losses, it can also lead to an enhancement of the local optical field. We demonstrate that around the resonance between the fundamental and 2nd order Laguerre-Gaussian modes of the cavity it is possible to obtain 50% enhancement of the atom-cavity coupling at the cavity center while still maintaining low cavity losses and high cavity-fiber optical coupling.

  4. Optical cavity resonator in an expanding universe

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei M.

    2015-02-01

    We study the cosmological evolution of frequency of a standing electromagnetic wave in a resonant optical cavity placed to the expanding manifold described by the Robertson-Walker metric. Because of the Einstein principle of equivalence (EEP), one can find a local coordinate system (a local freely falling frame), in which spacetime is locally Minkowskian. However, due to the conformal nature of the Robertson-Walker metric the conventional transformation to the local inertial coordinates introduces ambiguity in the physical interpretation of the local time coordinate, . Therefore, contrary to a common-sense expectation, a straightforward implementation of EEP alone does not allow us to unambiguously decide whether atomic clocks based on quantum transitions of atoms, ticks at the same rate as the clocks based on electromagnetic modes of a cavity. To resolve this ambiguity we have to analyse the cavity rigidity and the oscillation of its electromagnetic modes in an expanding universe by employing the full machinery of the Maxwell equations irrespectively of the underlying theory of gravity. We proceed in this way and found out that the size of the cavity and the electromagnetic frequency experience an adiabatic drift in conformal (unphysical) coordinates as the universe expands in accordance with the Hubble law. We set up the oscillation equation for the resonant electromagnetic modes, solve it by the WKB approximation, and reduce the coordinate-dependent quantities to their counterparts measured by a local observer who counts time with atomic clock. The solution shows that there is a perfect mutual cancellation of the adiabatic drift of cavity's frequency by space transformation to local coordinates and the time counted by the clocks based on electromagnetic modes of cavity has the same rate as that of atomic clocks. We conclude that if general relativity is correct and the local expansion of space is isotropic there should be no cosmological drift of frequency of a

  5. Double diffusion in arbitrary porous cavity: Part I

    NASA Astrophysics Data System (ADS)

    Ahamad, N. Ameer; Soudagar, Manzoor Elahi M.; Badruddin, Irfan Anjum

    2017-07-01

    Double diffusion refers to the heat and mass transfer that takes place simultaneously. The current work highlights the double diffusion when a solid block is placed at the bottom of a square porous cavity. The whole cavity is filed with saturated porous medium except the small block placed at the bottom left corner of the domain. The left vertical surface of porous cavity is maintained at concentration Ch and right vertical surface possesses lowest concentration Cc in the porous domain. The results are discussed in terms of isotherms, iso-concentration and streamlines inside the domain for various physical parameters. It is seen that the mass transfer is substantially different in present case as compared to the case of natural convection.

  6. Hybrid ion chains inside an optical cavity

    NASA Astrophysics Data System (ADS)

    Zhou, Zichao; Siverns, James; Quraishi, Qudsia

    2016-05-01

    Trapped ions remain a leading candidate for the implementation of large-scale quantum networks. These networks require nodes that can store and process quantum information as well as communicate with each other though photonic flying qubits. We propose to use hybrid ion chains of barium, for communication, and ytterbium, for quantum information processing. We report on progress in setting up a hybrid ion chain in a versatile four-blade trap using high numerical aperture collection optics. Although the visible photons produced from barium ions are more favorable as they are not suitable for long distance fiber communication. With this in mind, we intend to implement frequency conversion to overcome this issue. Also, with the view toward increasing the flying-qubit production rate, we propose a cavity-based system to enhance interactions between the ions and photons. The cavity axis is to be placed along the axial direction of the trap allowing a chain of multiple ions to interact with the cavity at the same time. With this configuration the atom-photon coupling strength can be improved by sqrt(N), where N is the number of ions. Experiments will focus on exploring the dynamics of hybrid ion chain, dual species quantum information processing, two-colour entanglement and phase gates assisted by the ion-cavity coupling are to be explored.

  7. Specimen illumination apparatus with optical cavity for dark field illumination

    DOEpatents

    Pinkel, Daniel; Sudar, Damir; Albertson, Donna

    1999-01-01

    An illumination apparatus with a specimen slide holder, an illumination source, an optical cavity producing multiple reflection of illumination light to a specimen comprising a first and a second reflective surface arranged to achieve multiple reflections of light to a specimen is provided. The apparatus can further include additional reflective surfaces to achieve the optical cavity, a slide for mounting the specimen, a coverslip which is a reflective component of the optical cavity, one or more prisms for directing light within the optical cavity, antifading solutions for improving the viewing properties of the specimen, an array of materials for analysis, fluorescent components, curved reflective surfaces as components of the optical cavity, specimen detection apparatus, optical detection equipment, computers for analysis of optical images, a plane polarizer, fiberoptics, light transmission apertures, microscopic components, lenses for viewing the specimen, and upper and lower mirrors above and below the specimen slide as components of the optical cavity. Methods of using the apparatus are also provided.

  8. Optical scatter of quantum noise filter cavity optics

    NASA Astrophysics Data System (ADS)

    Vander-Hyde, Daniel; Amra, Claude; Lequime, Michel; Magaña-Sandoval, Fabian; Smith, Joshua R.; Zerrad, Myriam

    2015-07-01

    Optical cavities to filter squeezed light for quantum noise reduction require optics with very low scattering losses. We report on measured light scattering from two super-polished fused silica optics before and after applying highly-reflective ion-beam sputtered dielectric coatings. We used an imaging scatterometer that illuminates the sample with a linearly polarized 1064 nm wavelength laser at a fixed angle of incidence and records images of back scatter for azimuthal angles in the plane of the laser beam. We extract from these images the bidirectional reflectance distribution function (BRDF) of the optics with and without coating and estimate their integrated scatter. We find that application of these coatings led to a more than 50% increase of the integrated wide-angle scatter, to 5.00+/- 0.30 and 3.38+/- 0.20 ppm for the two coated samples. In addition, the BRDF function of the coated optics takes on a pattern of maxima versus azimuthal angle. We compare with a scattering model to show that this is qualitatively consistent with roughness scattering from the coating layer interfaces. These results are part of a broader study to understand and minimize optical loss in quantum noise filter cavities for interferometric gravitational-wave detectors. The scattering measured for these samples is acceptable for the 16 m long filter cavities envisioned for the Laser Interferometer Gravitational-wave Observatory (LIGO), though reducing the loss further would improve LIGO’s quantum-noise limited performance.

  9. Optical Material Characterization Using Microdisk Cavities

    NASA Astrophysics Data System (ADS)

    Michael, Christopher P.

    Since Jack Kilby recorded his "Monolithic Idea" for integrated circuits in 1958, microelectronics companies have invested billions of dollars in developing the silicon material system to increase performance and reduce cost. For decades, the industry has made Moore's Law, concerning cost and transistor density, a self-fulfilling prophecy by integrating technical and material requirements vertically down their supply chains and horizontally across competitors in the market. At recent technology nodes, the unacceptable scaling behavior of copper interconnects has become a major design constraint by increasing latency and power consumption---more than 50% of the power consumed by high speed processors is dissipated by intrachip communications. Optical networks at the chip scale are a potential low-power high-bandwidth replacement for conventional global interconnects, but the lack of efficient on-chip optical sources has remained an outstanding problem despite significant advances in silicon optoelectronics. Many material systems are being researched, but there is no ideal candidate even though the established infrastructure strongly favors a CMOS-compatible solution. This thesis focuses on assessing the optical properties of materials using microdisk cavities with the intention to advance processing techniques and materials relevant to silicon photonics. Low-loss microdisk resonators are chosen because of their simplicity and long optical path lengths. A localized photonic probe is developed and characterized that employs a tapered optical-fiber waveguide, and it is utilized in practical demonstrations to test tightly arranged devices and to help prototype new fabrication methods. A case study in AlxGa1-xAs illustrates how the optical scattering and absorption losses can be obtained from the cavity-waveguide transmission. Finally, single-crystal Er2O3 epitaxially grown on silicon is analyzed in detail as a potential CMOS-compatable gain medium due to its high Er3

  10. Optical fiber tips functionalized with semiconductor photonic crystal cavities

    NASA Astrophysics Data System (ADS)

    Shambat, Gary; Provine, J.; Rivoire, Kelley; Sarmiento, Tomas; Harris, James; Vučković, Jelena

    2011-11-01

    We demonstrate a simple and rapid epoxy-based method for transferring photonic crystal (PC) cavities to the facets of optical fibers. Passive Si cavities were measured via fiber taper coupling as well as direct transmission from the fiber facet. Active quantum dot containing GaAs cavities showed photoluminescence that was collected both in free space and back through the original fiber. Cavities maintain a high quality factor (2000-4000) in both material systems. This design architecture provides a practical mechanically stable platform for the integration of photonic crystal cavities with macroscale optics and opens the door for innovative research on fiber-coupled cavity devices.

  11. Optical single photons on-demand teleported from microwave cavities

    NASA Astrophysics Data System (ADS)

    Barzanjeh, Sh; Vitali, D.; Tombesi, P.

    2013-03-01

    We propose a scheme for entangling the optical and microwave output modes of the respective cavities by using a micro mechanical resonator. The micro mechanical resonator, on one side, is capacitively coupled to the microwave cavity and, on the other side, it is coupled to a high-finesses optical cavity. We then show how this continuous variable entanglement can be profitably used to teleport the non-Gaussian number state |1> and the superposition (|0\\rangle +|1\\rangle )/\\sqrt 2 from the microwave cavity output mode onto an output of the optical cavity mode with fidelity much larger than the no-cloning limit.

  12. Diffraction-limited high-finesse optical cavities

    SciTech Connect

    Kleckner, Dustin; Irvine, William T. M.; Oemrawsingh, Sumant S. R.; Bouwmeester, Dirk

    2010-04-15

    High-quality optical cavities with wavelength-sized end mirrors are important to the growing field of micro-optomechanical systems. We present a versatile method for calculating the modes of diffraction limited optical cavities and show that it can be used to determine the effect of a wide variety of cavity geometries and imperfections. Additionally, we show these calculations agree remarkably well with FDTD simulations for wavelength-sized optical modes, even though our method is based on the paraxial approximation.

  13. Field quantization for open optical cavities

    NASA Astrophysics Data System (ADS)

    Viviescas, Carlos; Hackenbroich, Gregor

    2003-01-01

    We study the quantum properties of the electromagnetic field in optical cavities coupled to an arbitrary number of escape channels. We consider both inhomogeneous dielectric resonators with a scalar dielectric constant ɛ(r) and cavities defined by mirrors of arbitrary shape. Using the Feshbach projector technique we quantize the field in terms of a set of resonator and bath modes. We rigorously show that the field Hamiltonian reduces to the system-and-bath Hamiltonian of quantum optics. The field dynamics is investigated using the input-output theory of Gardiner and Collet. In the case of strong coupling to the external radiation field we find spectrally overlapping resonator modes. The mode dynamics is coupled due to the damping and noise inflicted by the external field. For wave chaotic resonators the mode dynamics is determined by a non-Hermitean random matrix. Upon including an amplifying medium, our dynamics of open-resonator modes may serve as a starting point for a quantum theory of random lasing.

  14. Daisy patterns in the passive ring cavity with diffusion effects

    NASA Astrophysics Data System (ADS)

    Le Berre, M.; Patrascu, A. S.; Ressayre, E.; Tallet, A.

    1996-02-01

    Near-field patterns with three to fifteen petals set on a single circle are numerically observed in the ring cavity device. Three to six petal daisies result from usual finite size effects. We point out the non-trivial formation of seven to fifteen petal daisies, with a top-hat input, and a small diffusion term that controls this daisy-type pattern formation, preventing the usual hexagonal structure to be formed.

  15. Temporal laser pulse manipulation using multiple optical ring-cavities

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor); Kojima, Jun (Inventor)

    2010-01-01

    An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities. The optical pulse stretcher system can also function as a high-repetition-rate (MHz) laser pulse generator, making it suitable for use as a stroboscopic light source for high speed ballistic projectile imaging studies, or it can be used for high speed flow diagnostics using a laser light sheet with digital particle imaging velocimetry. The optical pulse stretcher system can also be implemented using fiber optic components to realize a rugged and compact optical system that is alignment free and easy to use.

  16. Comparisons of hybrid radiosity-diffusion model and diffusion equation for bioluminescence tomography in cavity cancer detection

    NASA Astrophysics Data System (ADS)

    Chen, Xueli; Yang, Defu; Qu, Xiaochao; Hu, Hao; Liang, Jimin; Gao, Xinbo; Tian, Jie

    2012-06-01

    Bioluminescence tomography (BLT) has been successfully applied to the detection and therapeutic evaluation of solid cancers. However, the existing BLT reconstruction algorithms are not accurate enough for cavity cancer detection because of neglecting the void problem. Motivated by the ability of the hybrid radiosity-diffusion model (HRDM) in describing the light propagation in cavity organs, an HRDM-based BLT reconstruction algorithm was provided for the specific problem of cavity cancer detection. HRDM has been applied to optical tomography but is limited to simple and regular geometries because of the complexity in coupling the boundary between the scattering and void region. In the provided algorithm, HRDM was first applied to three-dimensional complicated and irregular geometries and then employed as the forward light transport model to describe the bioluminescent light propagation in tissues. Combining HRDM with the sparse reconstruction strategy, the cavity cancer cells labeled with bioluminescent probes can be more accurately reconstructed. Compared with the diffusion equation based reconstruction algorithm, the essentiality and superiority of the HRDM-based algorithm were demonstrated with simulation, phantom and animal studies. An in vivo gastric cancer-bearing nude mouse experiment was conducted, whose results revealed the ability and feasibility of the HRDM-based algorithm in the biomedical application of gastric cancer detection.

  17. Localized Turing patterns in nonlinear optical cavities

    NASA Astrophysics Data System (ADS)

    Kozyreff, G.

    2012-05-01

    The subcritical Turing instability is studied in two classes of models for laser-driven nonlinear optical cavities. In the first class of models, the nonlinearity is purely absorptive, with arbitrary intensity-dependent losses. In the second class, the refractive index is real and is an arbitrary function of the intracavity intensity. Through a weakly nonlinear analysis, a Ginzburg-Landau equation with quintic nonlinearity is derived. Thus, the Maxwell curve, which marks the existence of localized patterns in parameter space, is determined. In the particular case of the Lugiato-Lefever model, the analysis is continued to seventh order, yielding a refined formula for the Maxwell curve and the theoretical curve is compared with recent numerical simulation by Gomila et al. [D. Gomila, A. Scroggie, W. Firth, Bifurcation structure of dissipative solitons, Physica D 227 (2007) 70-77.

  18. Cavity solitons and localized patterns in a finite-size optical cavity

    NASA Astrophysics Data System (ADS)

    Kozyreff, G.; Gelens, L.

    2011-08-01

    In appropriate ranges of parameters, laser-driven nonlinear optical cavities can support a wide variety of optical patterns, which could be used to carry information. The intensity peaks appearing in these patterns are called cavity solitons and are individually addressable. Using the Lugiato-Lefever equation to model a perfectly homogeneous cavity, we show that cavity solitons can only be located at discrete points and at a minimal distance from the edges. Other localized states which are attached to the edges are identified. By interpreting these patterns in an information coding frame, the information capacity of this dynamical system is evaluated. The results are explained analytically in terms of the the tail characteristics of the cavity solitons. Finally, the influence of boundaries and of cavity imperfections on cavity solitons are compared.

  19. Photon momentum and optical forces in cavities

    NASA Astrophysics Data System (ADS)

    Partanen, Mikko; Häyrynen, Teppo; Oksanen, Jani; Tulkki, Jukka

    2016-03-01

    During the past century the electromagnetic field momentum in material media has been under debate in the Abraham-Minkowski controversy as convincing arguments have been advanced in favor of both the Abraham and Minkowski forms of photon momentum. Here we study the photon momentum and optical forces in cavity structures in the cases of dynamical and steady state fields. In the description of the single-photon transmission process we use a field-kinetic one-photon theory. Our model suggests that in the medium photons couple with the induced atomic dipoles forming polariton quasiparticles with the Minkowski form momentum. The Abraham momentum can be associated to the electromagnetic field part of the coupled polariton state. The polariton with the Minkowski momentum is shown to obey the uniform center of mass of energy motion that has previously been interpreted to support only the Abraham momentum. When describing the steady state non-equilibrium field distributions we use the recently developed quantized fluctuational electrodynamics (QFED) formalism. While allowing detailed studies of light propagation and quantum field fluctuations in interfering structures, our methods also provide practical tools for modeling optical energy transfer and the formation of thermal balance in nanodevices as well as studying electromagnetic forces in optomechanical devices.

  20. Optically thin hybrid cavity for terahertz photo-conductive detectors

    DOE PAGES

    Thompson, Robert J.; Siday, T.; Glass, S.; ...

    2017-01-23

    Here, the efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that themore » nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities.« less

  1. Optically thin hybrid cavity for terahertz photo-conductive detectors

    NASA Astrophysics Data System (ADS)

    Thompson, R. J.; Siday, T.; Glass, S.; Luk, T. S.; Reno, J. L.; Brener, I.; Mitrofanov, O.

    2017-01-01

    The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that the nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities.

  2. A master equation for a two-sided optical cavity

    PubMed Central

    Barlow, Thomas M.; Bennett, Robert; Beige, Almut

    2015-01-01

    Quantum optical systems, like trapped ions, are routinely described by master equations. The purpose of this paper is to introduce a master equation for two-sided optical cavities with spontaneous photon emission. To do so, we use the same notion of photons as in linear optics scattering theory and consider a continuum of travelling-wave cavity photon modes. Our model predicts the same stationary state photon emission rates for the different sides of a laser-driven optical cavity as classical theories. Moreover, it predicts the same time evolution of the total cavity photon number as the standard standing-wave description in experiments with resonant and near-resonant laser driving. The proposed resonator Hamiltonian can be used, for example, to analyse coherent cavity-fiber networks [E. Kyoseva et al., New J. Phys. 14, 023023 (2012)].

  3. Quantum optics, cavity QED, and quantum optomechanics

    NASA Astrophysics Data System (ADS)

    Meystre, Pierre

    2013-05-01

    Quantum optomechanics provides a universal tool to achieve the quantum control of mechanical motion. It does that in devices spanning a vast range of parameters, with mechanical frequencies from a few Hertz to GHz, and with masses from 10-20 g to several kilos. Its underlying ideas can be traced back to the study of gravitational wave antennas, quantum optics, cavity QED and laser cooling which, when combined with the recent availability of advanced micromechanical and nanomechanical devices, opens a path to the realization of macroscopic mechanical systems that operate deep in the quantum regime. At the fundamental level this development paves the way to experiments that will lead to a more profound understanding of quantum mechanics; and from the point of view of applications, quantum optomechanical techniques will provide motion and force sensing near the fundamental limit imposed by quantum mechanics (quantum metrology) and significantly expand the toolbox of quantum information science. After a brief summary of key historical developments, the talk will give a broad overview of the current state of the art of quantum optomechanics, and comment on future prospects both in applied and in fundamental science. Work supported by NSF, ARO and the DARPA QuASAR and ORCHID programs.

  4. Lattice-cavity solitons in a degenerate optical parametric oscillator

    SciTech Connect

    Egorov, O. A.; Lederer, F.

    2007-11-15

    We predict the existence of lattice-cavity solitons for a quadratic nonlinear cavity, where the linear losses are compensated for by the optical pump at second harmonic (degenerate optical parametric oscillator), and which is endowed with a one-dimensional photonic lattice. In the limit of strong discreteness (weak coupling) this kind of soliton solution contains as the subclass the quadratic discrete cavity solitons. The nonlinear coupling between the Bloch waves of different photonics bands allows for the formation of a reach variety of localized solutions. In particular, different types of multiband lattice-cavity solitons can be identified. Most types of lattice-cavity solitons do not have counterparts, neither in conventional planar microresonators nor in genuine discrete systems as an array of weakly coupled cavities. We show that these solitons may destabilize as a consequence of the competition between Bloch waves of different photonic bands.

  5. Single ion coupled to an optical fiber cavity.

    PubMed

    Steiner, Matthias; Meyer, Hendrik M; Deutsch, Christian; Reichel, Jakob; Köhl, Michael

    2013-01-25

    We present the realization of a combined trapped-ion and optical cavity system, in which a single Yb(+) ion is confined by a micron-scale ion trap inside a 230 μm-long optical fiber cavity. We characterize the spatial ion-cavity coupling and measure the ion-cavity coupling strength using a cavity-stimulated Λ transition. Owing to the small mode volume of the fiber resonator, the coherent coupling strength between the ion and a single photon exceeds the natural decay rate of the dipole moment. This system can be integrated into ion-photon quantum networks and is a step towards cavity quantum electrodynamics based quantum information processing with trapped ions.

  6. Cavity nonlinear optics with monolayer materials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Majumdar, Arka

    2017-02-01

    Realizing low-power (few-photon) nonlinear optics in a scalable way is important for both fundamental scientific studies to build strongly correlated "quantum fluids of light" and technological applications, including optical information processing. In recent years, such single photon nonlinearity has been reported using cavity coupled single emitters, including quantum dots, and atoms. However, the macroscopic size of atomic physics cavities, and stochastic spatial and spectral nature of quantum dots pose a serious problem for the scalability. In my talk, I will introduce a new platform with cavity coupled to patterned monolayer materials to accomplish this goal. I will present theoretical analysis of a coupled system of cavity-transition metal dichalcogenides and provide some preliminary experimental data on nonlinear optics with cavity and monolayer materials.

  7. Multispectral fluorescence diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Lo, Pei-An; Cho, Jaedu; Nouizi, Farouk; Chiang, Huihua Kenny; Gulsen, Gultekin

    2017-03-01

    Fluorescence diffuse optical tomography (FDOT) has been widely used for in vivo small animal studies and the illposed problem in reconstruction can be eased by utilizing structural a priori obtained from an anatomic imaging modality. In this study, a multispectral fluorescence tomography (FT) is used, which has shown the ability to detect subtle shifts in the ICG absorption spectrum in our previous study. The imaging system is in trans-illumination mode with a swept-wavelength laser and a CCD on a rotation gantry and the structural image from the X-ray computed tomography is used to guide and constrain the FT reconstruction algorithm. In this work, a phantom with two inclusions filled with different fluorophores is utilized to evaluate whether the spectral information obtained using sweptwavelength laser can distinguish these two inclusions. The images are captured from 8 different views with three different wavelengths.

  8. Impurity-free quantum well intermixing for large optical cavity high-power laser diode structures

    NASA Astrophysics Data System (ADS)

    Kahraman, Abdullah; Gür, Emre; Aydınlı, Atilla

    2016-08-01

    We report on the correlation of atomic concentration profiles of diffusing species with the blueshift of the quantum well luminescence from both as-grown and impurity free quantum wells intermixed on actual large optical cavity high power laser diode structures. Because it is critical to suppress catastrophic optical mirror damage, sputtered SiO2 and thermally evaporated SrF2 were used both to enhance and suppress quantum well intermixing, respectively, in these (Al)GaAs large optical cavity structures. A luminescence blueshift of 55 nm (130 meV) was obtained for samples with 400 nm thick sputtered SiO2. These layers were used to generate point defects by annealing the samples at 950 °C for 3 min. The ensuing Ga diffusion observed as a shifting front towards the surface at the interface of the GaAs cap and AlGaAs cladding, as well as Al diffusion into the GaAs cap layer, correlates well with the observed luminescence blue shift, as determined by x-ray photoelectron spectroscopy. Although this technique is well-known, the correlation between the photoluminescence peak blue shift and diffusion of Ga and Al during impurity free quantum well intermixing on actual large optical cavity laser diode structures was demonstrated with both x ray photoelectron and photoluminescence spectroscopy, for the first time.

  9. Different optical properties in different periodic slot cavity geometrical morphologies

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Shen, Meng; Du, Lan; Deng, Caisong; Ni, Haibin; Wang, Ming

    2016-09-01

    In this paper, optical properties of two-dimensional periodic annular slot cavity arrays in hexagonal close-packing on a silica substrate are theoretically characterized by finite difference time domain (FDTD) simulation method. By simulating reflectance spectra, electric field distribution, and charge distribution, we confirm that multiple cylindrical surface plasmon resonances can be excited in annular inclined slot cavities by linearly polarized light, in which the four reflectance dips are attributed to Fabry-Perot cavity resonances in the coaxial cavity. A coaxial waveguide mode TE11 will exist in these annular cavities, and the wavelengths of these reflectance dips are effectively tailored by changing the geometrical pattern of slot cavity and the dielectric materials filled in the cavities. These resonant wavelengths are localized in annular cavities with large electric field enhancement and dissipate gradually due to metal loss. The formation of an absorption peak can be explained from the aspect of phase matching conditions. We observed that the proposed structure can be tuned over the broad spectral range of 600-4000 nm by changing the outer and inner radii of the annular gaps, gap surface topography. Meanwhile, different lengths of the cavity may cause the shift of resonance dips. Also, we study the field enhancement at different vertical locations of the slit. In addition, dielectric materials filling in the annular gaps will result in a shift of the resonance wavelengths, which make the annular cavities good candidates for refractive index sensors. The refractive index sensitivity of annular cavities can also be tuned by the geometry size and the media around the cavity. Annular cavities with novel applications can be implied as surface enhanced Raman spectra substrates, refractive index sensors, nano-lasers, and optical trappers. Project supported by the National Natural Science Foundation of China (Grant No. 61178044), the Natural Science Foundation

  10. Calculations of laser cavity dumping for optical communications

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Rayman, M. D.

    1988-01-01

    For deep-space pulse-position modulation (PPM) optical communication links using Nd:YAG lasers, two types of laser transmitter modulation techniques are available for efficiently producing laser pulses over a broad range of repetition rates: Q-switching and cavity dumping. The desired modulation scheme is dependent on the required pulse repetition frequency and link parameters. These two techniques are discussed, theoretical and numerical calculations of the internal energy of the laser cavity in cavity dumping are described, and an example of cavity dumping is applied to a link for a proposed experiment package on Cassini.

  11. Optimal feedback in efficient single-cavity optical parametric oscillators

    SciTech Connect

    Petnikova, V M; Shuvalov, Vladimir V

    2010-09-10

    An approach based on the description of competition of quadratic processes of merging and decomposition of quanta resulting in the formation of cnoidal waves on an effective cascade cubic Kerr-type nonlinearity is used to optimise the scheme of a single-cavity optical parametric oscillator. It is shown that the use of a feedback circuit (cavity) decreases the period of cnoidal waves produced in a nonlinear crystal, while the optimisation procedure of the transfer constant of this circuit (reflectivity of the output mirror of the cavity) is reduced to matching this period with the nonlinear crystal length. (optical parametric oscillators)

  12. Polarization-controlled optical ring cavity (PORC) tunable pulse stretcher

    NASA Astrophysics Data System (ADS)

    Williamson, Andrew P.; Kiefer, Johannes

    2016-08-01

    A new concept and a theoretical approach for modeling a tunable polarization-controlled optical ring cavity pulse stretcher is demonstrated. The technique discussed herein permits highly simplified and flexible tuning of the temporal shape of nanosecond duration pulses. Using half-wave plates positioned extra- and intracavity, transmission to reflection ratios across both input faces of a polarization beam splitter can easily be controlled. The resulting models indicate a further reduction in peak intensity of 30%, with respect to conventional dielectric beam splitting optical ring cavities, when configured under equivalent and optimized cavity settings.

  13. Diffuse Optics for Tissue Monitoring and Tomography

    PubMed Central

    Durduran, T; Choe, R; Baker, W B; Yodh, A G

    2015-01-01

    This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative assessment of oxy- and deoxy-hemoglobin concentrations and blood flow are desired. The theoretical basis for near-infrared or diffuse optical spectroscopy (NIRS or DOS, respectively) is developed, and the basic elements of diffuse optical tomography (DOT) are outlined. We also discuss diffuse correlation spectroscopy (DCS), a technique whereby temporal correlation functions of diffusing light are transported through tissue and are used to measure blood flow. Essential instrumentation is described, and representative brain and breast functional imaging and monitoring results illustrate the workings of these new tissue diagnostics. PMID:26120204

  14. Controllable optical switch using a Bose-Einstein condensate in an optical cavity

    SciTech Connect

    Yang Shuai; Zubairy, M. Suhail; Al-Amri, M.; Evers, Joerg

    2011-05-15

    The optical bistability of an ultracold atomic ensemble located in a small-volume ultrahigh-finesse optical cavity is investigated. We find that a transverse pumping field can be used to control the bistable behavior of the intracavity photons induced by the input pumping along the cavity axis. This phenomenon can be used as a controllable optical switch.

  15. Nanosecond pulsed laser texturing of optical diffusers

    NASA Astrophysics Data System (ADS)

    Alqurashi, Tawfiq; Sabouri, Aydin; Yetisen, Ali K.; Butt, Haider

    2017-02-01

    High-quality optical glass diffusers have applications in aerospace, displays, imaging systems, medical devices, and optical sensors. The development of rapid and accurate fabrication techniques is highly desirable for their production. Here, a micropatterning method for the fast fabrication of optical diffusers by means of nanosecond pulsed laser ablation is demonstrated (λ=1064 nm, power=7.02, 9.36 and 11.7 W and scanning speed=200 and 800 mm s-1). The experiments were carried out by point-to-point texturing of a glass surface in spiral shape. The laser machining parameters, the number of pulses and their power had significant effect on surface features. The optical characteristics of the diffusers were characterized at different scattering angles. The features of the microscale structures influenced average roughness from 0.8 μm to 1.97 μm. The glass diffusers scattered light at angles up to 20° and their transmission efficiency were measured up to ˜97% across the visible spectrum. The produced optical devices diffuse light less but do so with less scattering and energy losses as compared to opal diffusing glass. The presented fabrication method can be applied to any other transparent material to create optical diffusers. It is anticipated that the optical diffusers presented in this work will have applications in the production of LED spotlights and imaging devices.

  16. Stochastic electrodynamics simulations for collective atom response in optical cavities

    NASA Astrophysics Data System (ADS)

    Lee, Mark D.; Jenkins, Stewart D.; Bronstein, Yael; Ruostekoski, Janne

    2017-08-01

    We study the collective optical response of an atomic ensemble confined within a single-mode optical cavity by stochastic electrodynamics simulations that include the effects of atomic position correlations, internal level structure, and spatial variations in cavity coupling strength and atom density. In the limit of low light intensity, the simulations exactly reproduce the full quantum field-theoretical description for cold stationary atoms and at higher light intensities we introduce semiclassical approximations to atomic saturation that we compare with the exact solution in the case of two atoms. We find that collective subradiant modes of the atoms, with very narrow linewidths, can be coupled to the cavity field by spatial variation of the atomic transition frequency and resolved at low intensities, and show that they can be specifically driven by tailored transverse pumping beams. We show that the cavity optical response, in particular both the subradiant mode profile and the resonance shift of the cavity mode, can be used as a diagnostic tool for the position correlations of the atoms and hence the atomic quantum many-body phase. The quantum effects are found to be most prominent close to the narrow subradiant mode resonances at high light intensities. Although an optical cavity can generally strongly enhance quantum fluctuations via light confinement, we show that the semiclassical approximation to the stochastic electrodynamics model provides at least a qualitative agreement with the exact optical response outside the subradiant mode resonances even in the presence of significant saturation of the atoms.

  17. Slow light in evanescently coupled optical cavities containing quantum dots

    NASA Astrophysics Data System (ADS)

    Ergecen, Emre

    2014-05-01

    Ability to tune the group velocity of a light pulse is of great importance for optical communication applications and realization of quantum information processing. Tunability of group velocity can be achieved by using either optical or electronic resonances. Tunability of an optical resonance depends on the change in refractive index of the cavity material. However, since electro-optical coefficients of non-engineered materials are quite small, the tuning range of optical resonances by electric field is narrow. This makes tuning by electric field impractical for most applications. Quantum dot (QD) coupled to a photonic crystal cavity is a useful hybrid system exhibiting nonlinear features. In this work, we analyze the use of quantum dot - optical cavity hybrid systems to engineer nonlinear waveguides susceptible to electric fields. We start by theoretically analyzing the optical pulse propagation at low-photon number excitation limit in a periodically arranged strongly coupled quantum dot - photonic crystal system. A one dimensional periodic array of evanescently coupled photonic cavities (coupled resonator optical waveguides, CROWs) containing non-interacting quantum dots allows us to tune the group velocity and the bandwidth of the pulse by adjusting the cavity/QD coupling. Tunable group velocity can be achieved by applying an external electric field which will result in a significant decrease in the cavity/QD coupling because of DC Stark effect. We also show that, using this approach, light pulses can be slowed down or stored by compressing the pulse bandwidth adiabatically and reversibly. Adiabatic bandwidth compression can be achieved by slowly decreasing the coupling strength when the light pulse is inside the coupled resonator optical waveguide. The energy splitting and the coupling constant after applying electric field is calculated by using perturbation theory for two level systems. With our approach, nonlinear materials highly susceptible to electric

  18. Design and optimization of microbolometer multilayer optical cavity

    NASA Astrophysics Data System (ADS)

    Awad, E.; Al-Khalli, N.; Abdel-Rahman, M.; Debbar, N.; Alduraibi, M.

    2015-03-01

    Microbolometers are the most widely used detectors in long-wave infrared uncooled thermal imagers. An optical cavity is required within a microbolometer structure to increase its optical absorption. In this work we present a detailed study on the design and optimization of a microbolometer optical cavity using Essential-Macleod package. In the simulations, the cavity is considered as thin film multi-layers that form cascaded Fabry-Perot optical cavities. In the design phase, the layers structures are selected including materials and initial thickness. The absorbing layers are chosen to be vanadium-pentoxide (V2O5) and titanium (Ti). In the optimization phase, the designed layer thicknesses are varied to maximize optical absorption within the absorbing layers. The simulations show that Ti layer absorption dominates over V2O5 layer. Also, the optimization proves that the air-gap cavity thickness is not simply quarter-wavelength because of the complex cascaded Fabry-Perot structure. The optimized air-gap thickness here is ≈3.5 µm at 10.6µm wavelength.

  19. Design and optimization of microbolometer multilayer optical cavity

    SciTech Connect

    Awad, E.; Al-Khalli, N.; Debbar, N.; Abdel-Rahman, M.; Alduraibi, M.

    2015-03-30

    Microbolometers are the most widely used detectors in long-wave infrared uncooled thermal imagers. An optical cavity is required within a microbolometer structure to increase its optical absorption. In this work we present a detailed study on the design and optimization of a microbolometer optical cavity using Essential-Macleod package. In the simulations, the cavity is considered as thin film multi-layers that form cascaded Fabry-Perot optical cavities. In the design phase, the layers structures are selected including materials and initial thickness. The absorbing layers are chosen to be vanadium-pentoxide (V{sub 2}O{sub 5}) and titanium (Ti). In the optimization phase, the designed layer thicknesses are varied to maximize optical absorption within the absorbing layers. The simulations show that Ti layer absorption dominates over V{sub 2}O{sub 5} layer. Also, the optimization proves that the air-gap cavity thickness is not simply quarter-wavelength because of the complex cascaded Fabry-Perot structure. The optimized air-gap thickness here is ≈3.5 µm at 10.6µm wavelength.

  20. Transmission spectrum of an optical cavity containing N atoms

    SciTech Connect

    Leslie, Sabrina; Shenvi, Neil; Brown, Kenneth R.; Whaley, K. Birgitta; Stamper-Kurn, Dan M.

    2004-04-01

    The transmission spectrum of a high-finesse optical cavity containing an arbitrary number of trapped atoms is presented in the zero-temperature, low saturation limit. We take spatial and motional effects into account and show that in the limit of strong coupling, the important spectral features can be determined for an arbitrary number of atoms, N. We also show that these results have important ramifications in limiting our ability to determine the number of atoms in the cavity.

  1. Dynamical entanglement purification using chains of atoms and optical cavities

    SciTech Connect

    Gonta, Denis; Loock, Peter van

    2011-10-15

    In the framework of cavity QED, we propose a practical scheme to purify dynamically a bipartite entangled state using short chains of atoms coupled to high-finesse optical cavities. In contrast to conventional entanglement purification protocols, we avoid controlled-not gates, thus reducing complicated pulse sequences and superfluous qubit operations. Our interaction scheme works in a deterministic way and, together with entanglement distribution and swapping, opens a route toward efficient quantum repeaters for long-distance quantum communication.

  2. Non-adiabatic Dynamics of Molecules in Optical Cavities

    NASA Astrophysics Data System (ADS)

    Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul

    Molecular systems coupled to optical cavities are promising candidates for a novel kind of photo chemistry. Strong coupling to the vacuum field of the cavity can modify the potential energy surfaces opening up new reaction pathways. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime. The possibilities for photo chemistry are demonstrated for a set of model systems representing typical situations found in molecules. Supported by the Alexander von Humboldt Foundation.

  3. Detecting magnetically guided atoms with an optical cavity.

    PubMed

    Haase, Albrecht; Hessmo, Björn; Schmiedmayer, Jörg

    2006-01-15

    We show that a low-finesse cavity can be efficient for detecting neutral atoms. The low finesse can be compensated for by decreasing the mode waist of the cavity. We have used a near-concentric resonator with a beam waist of 12 microm and a finesse of only 1100 to detect magnetically guided Rb atoms with a detection sensitivity of 0.1 atom in the mode volume. For future experiments on single-atom detection and cavity QED applications, it should be beneficial to use miniaturized optical resonators integrated on atom chips.

  4. Diode Laser Optically Injected by Resonance of a Monolithic Cavity

    NASA Astrophysics Data System (ADS)

    Peng, Yu; Zhao, Yang; Li, Ye; Yang, Tao; Cao, Jian-Ping; Fang, Zhan-Jun; Zang, Er-Jun

    2011-11-01

    We demonstrate a self-injection locking extended cavity diode laser (ECDL) using resonant optical feedback from the p-polarization of a monolithic folded Fabry—Perot parallel cavity (MFC). The full width at half maximum of the MFC resonance is 31 MHz. With the help of a narrow-linewidth reference laser, the linewidth of the ECDL is measured to be about 7 kHz. The frequency of the laser could be tuned at 160 MHz with an amplitude of 40 V by a PZT mounted on the monolithic cavity and the voltage tuning coefficient is about 4 MHz/V.

  5. Extreme diffusion limited electropolishing of niobium radiofrequency cavities

    NASA Astrophysics Data System (ADS)

    Crawford, Anthony C.

    2017-03-01

    A deeply modulated, regular, continuous, oscillating current waveform is reliably and repeatably achieved during electropolishing of niobium single-cell elliptical radiofrequency cavities. Details of the technique and cavity test results are reported here. The method is applicable for cavity frequencies in the range 500 MHz to 3.9 GHz and can be extended to multicell structures.

  6. Extreme diffusion limited electropolishing of niobium radiofrequency cavities

    DOE PAGES

    Crawford, Anthony C.

    2017-01-04

    In this study, a deeply modulated, regular, continuous, oscillating current waveform is reliably and repeatably achieved during electropolishing of niobium single-cell elliptical radiofrequency cavities. Details of the technique and cavity test results are reported here. The method is applicable for cavity frequencies in the range 500 MHz to 3.9 GHz and can be extended to multicell structures.

  7. Optical Cavities and Gravity - Wave Detectors

    NASA Astrophysics Data System (ADS)

    Drever, Ronald

    When invited to participate in this Symposium for John Hall ("Jan" to his friends) I was enthusiastic to come, but not sure what I should talk about. Eventually it seemed the best thing might just be to recount how I first came to meet Jan, the exciting time we spent working together on a new technique for stabilizing lasers to cavities, and some of the things that have developed from this and some of his other work…

  8. Scattering-Free Optical Levitation of a Cavity Mirror

    NASA Astrophysics Data System (ADS)

    Guccione, G.; Hosseini, M.; Adlong, S.; Johnsson, M. T.; Hope, J.; Buchler, B. C.; Lam, P. K.

    2013-11-01

    We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, the mirror is supported by a tripod where each leg of the tripod is a Fabry-Perot cavity. The macroscopic state of the mirror is coherently coupled to the supporting cavity modes allowing coherent interrogation and manipulation of the mirror motion. The proposed scheme is an extreme example of the optical spring, where a mechanical oscillator is isolated from the environment and its mechanical frequency and macroscopic state can be manipulated solely through optical fields. We model the stability of the system and find a three-dimensional lattice of trapping points where cavity resonances allow for buildup of optical field sufficient to support the weight of the mirror. Our scheme offers a unique platform for studying quantum and classical optomechanics and can potentially be used for precision gravitational field sensing and quantum state generation.

  9. Optical trapping of dielectric nanoparticles in resonant cavities

    SciTech Connect

    Hu Juejun; Lin Shiyun; Crozier, Kenneth; Kimerling, Lionel C.

    2010-11-15

    We theoretically investigate the opto-mechanical interactions between a dielectric nanoparticle and the resonantly enhanced optical field inside a high Q, small-mode-volume optical cavity. We develop an analytical method based on open system analysis to account for the resonant perturbation due to particle introduction and predict trapping potential in good agreement with three-dimensional (3D) finite-difference time-domain (FDTD) numerical simulations. Strong size-dependent trapping dynamics distinctly different from free-space optical tweezers arise as a consequence of the finite cavity perturbation. We illustrate single nanoparticle trapping from an ensemble of monodispersed particles based on size-dependent trapping dynamics. We further discover that the failure of the conventional dipole approximation in the case of resonant cavity trapping originates from a new perturbation interaction mechanism between trapped particles and spatially localized photons.

  10. Scattering-free optical levitation of a cavity mirror.

    PubMed

    Guccione, G; Hosseini, M; Adlong, S; Johnsson, M T; Hope, J; Buchler, B C; Lam, P K

    2013-11-01

    We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, the mirror is supported by a tripod where each leg of the tripod is a Fabry-Perot cavity. The macroscopic state of the mirror is coherently coupled to the supporting cavity modes allowing coherent interrogation and manipulation of the mirror motion. The proposed scheme is an extreme example of the optical spring, where a mechanical oscillator is isolated from the environment and its mechanical frequency and macroscopic state can be manipulated solely through optical fields. We model the stability of the system and find a three-dimensional lattice of trapping points where cavity resonances allow for buildup of optical field sufficient to support the weight of the mirror. Our scheme offers a unique platform for studying quantum and classical optomechanics and can potentially be used for precision gravitational field sensing and quantum state generation.

  11. Modulation-free optical locking of an external-cavity diode laser to a filter cavity.

    PubMed

    Hayasaka, Kazuhiro

    2011-06-15

    Optical locking to a filter cavity is an effective method to eliminate the limitations of an external-cavity diode laser, such as broad spontaneous emission backgrounds and frequency jitters. Stable operation of the optical locking requires simultaneous control of the feedback phase and the diode-laser frequency. Frequency dither is usually used to extract the two error signals, but this causes extra frequency modulation in the output beam. A modulation-free method for deriving the error signals by modulating the laser-cavity coupling strength is demonstrated with a violet diode laser. A modulation-free linewidth upper limit of about 7 kHz for a 1 s measurement is realized by the method.

  12. Microgel photonics: a breathing cavity onto optical fiber tip

    NASA Astrophysics Data System (ADS)

    Ricciardi, A.; Aliberti, A.; Giaquinto, M.; Micco, A.; Cusano, A.

    2015-09-01

    We experimentally demonstrate a novel multifunctional optical fiber probe resulting from the integration between two rapidly emerging technologies such as Lab-on-Fiber and Microgel Photonics. The device consists of a microgel based cavity formed by metallic slabs supporting plasmonic resonances, directly integrated on the optical fiber tip. By exploiting the multiresponsivity of microgel systems, variations of temperature, PH, ionic strength, as well as molecular binding events, make the cavity to `breath', thus modulating the interference pattern in the reflection spectrum. The microgel layer can be synthetized in such a way to obtain different thicknesses, corresponding to different operating regimes, opening new avenues for the realization of advanced multifunctional nanoprobes.

  13. Ultrafast Optics: Vector Cavity Fiber Lasers - Physics and Technology

    DTIC Science & Technology

    2016-06-14

    AFRL-AFOSR-JP-TR-2016-0065 Ultrafast Optics - Vector Cavity Lasers: Physics and Technology Dingyuan Tang NANYANG TECHNOLOGICAL UNIVERSITY Final... Physics and Technology 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-13-1-4096 5c.  PROGRAM ELEMENT NUMBER 61102F 6.  AUTHOR(S) Dingyuan Tang 5d...AOARD Grant FA2386-13-1-4096 “Ultrafast Optics: Vector Cavity Fiber Lasers - Physics and Technology” Name of Principal Investigator: A/Prof. Tang

  14. Ultrafast Optics - Vector Cavity Lasers: Physics and Technology

    DTIC Science & Technology

    2016-06-14

    AFRL-AFOSR-JP-TR-2016-0065 Ultrafast Optics - Vector Cavity Lasers: Physics and Technology Dingyuan Tang NANYANG TECHNOLOGICAL UNIVERSITY Final... Physics and Technology 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-13-1-4096 5c.  PROGRAM ELEMENT NUMBER 61102F 6.  AUTHOR(S) Dingyuan Tang 5d...AOARD Grant FA2386-13-1-4096 “Ultrafast Optics: Vector Cavity Fiber Lasers - Physics and Technology” Name of Principal Investigator: A/Prof. Tang

  15. Optical re-injection in cavity-enhanced absorption spectroscopy

    PubMed Central

    Leen, J. Brian; O’Keefe, Anthony

    2014-01-01

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10−10 cm−1/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\sqrt {{\\rm Hz;}}$\\end{document} Hz ; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features. PMID:25273701

  16. Optical re-injection in cavity-enhanced absorption spectroscopy.

    PubMed

    Leen, J Brian; O'Keefe, Anthony

    2014-09-01

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10(-10) cm(-1)/√Hz; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  17. Optical re-injection in cavity-enhanced absorption spectroscopy

    SciTech Connect

    Leen, J. Brian O’Keefe, Anthony

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  18. Triangular and honeycomb lattices of cold atoms in optical cavities

    NASA Astrophysics Data System (ADS)

    Safaei, Shabnam; Miniatura, Christian; Grémaud, Benoît.

    2015-10-01

    We consider a two-dimensional homogeneous ensemble of cold bosonic atoms loaded inside two optical cavities and pumped by a far-detuned external laser field. We examine the conditions for these atoms to self-organize into triangular and honeycomb lattices as a result of superradiance. By collectively scattering the pump photons, the atoms feed the initially empty cavity modes. As a result, the superposition of the pump and cavity fields creates a space-periodic light-shift external potential and atoms self-organize into the potential wells of this optical lattice. Depending on the phase of the cavity fields with respect to the pump laser, these minima can either form a triangular or a hexagonal lattice. By numerically solving the dynamical equations of the coupled atom-cavity system, we have shown that the two stable atomic structures at long times are the triangular lattice and the honeycomb lattice with equally populated sites. We have also studied how to drive atoms from one lattice structure to another by dynamically changing the phase of the cavity fields with respect to the pump laser.

  19. Optical cavity integrated surface ion trap for enhanced light collection

    NASA Astrophysics Data System (ADS)

    Benito, Francisco M.

    Ion trap systems allow the faithful storage and manipulation of qubits encoded in the energy levels of the ions, and can be interfaced with photonic qubits that can be transmitted to connect remote quantum systems. Single photons transmitted from two remote sites, each entangled with one quantum memory, can be used to entangle distant quantum memories by interfering on a beam splitter. Efficient remote entanglement generation relies upon efficient light collection from single ions into a single mode fiber. This can be realized by integrating an ion trap with an optical cavity and employing the Purcell effect for enhancing the light collection. Remote entanglement can be used as a resource for a quantum repeater for provably secure long-distance communication or as a method for communicating within a distributed quantum information processor. We present the integration of a 1 mm optical cavity with a micro-fabricated surface ion trap. The plano-concave cavity is oriented normal to the chip surface where the planar mirror is attached underneath the trap chip. The cavity is locked using a 780 nm laser which is stabilized to Rubidium and shifted to match the 369 nm Doppler transition in Ytterbium. The linear ion trap allows ions to be shuttled in and out of the cavity mode. The Purcell enhancement of spontaneous emission into the cavity mode would then allow efficient collection of the emitted photons, enabling faster remote entanglement generation.

  20. Optothermal transport behavior in whispering gallery mode optical cavities

    SciTech Connect

    Soltani, Soheil; Armani, Andrea M.

    2014-08-04

    Over the past century, whispering gallery mode optical cavities have enabled numerous advances in science and engineering, such as discoveries in quantum mechanics and non-linear optics, as well as the development of optical gyroscopes and add drop filters. One reason for their widespread appeal is their ability to confine light for long periods of time, resulting in high circulating intensities. However, when sufficiently large amounts of optical power are coupled into these cavities, they begin to experience optothermal or photothermal behavior, in which the optical energy is converted into heat. Above the optothermal threshold, the resonance behavior is no longer solely defined by electromagnetics. Previous work has primarily focused on the role of the optothermal coefficient of the material in this instability. However, the physics of this optothermal behavior is significantly more complex. In the present work, we develop a predictive theory based on a generalizable analytical expression in combination with a geometry-specific COMSOL Multiphysics finite element method model. The simulation couples the optical and thermal physics components, accounting for geometry variations as well as the temporal and spatial profile of the optical field. To experimentally verify our theoretical model, the optothermal thresholds of a series of silica toroidal resonant cavities are characterized at different wavelengths (visible through near-infrared) and using different device geometries. The silica toroid offers a particularly rigorous case study for the developed optothermal model because of its complex geometrical structure which provides multiple thermal transport paths.

  1. Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Siller, Brian; Mills, Andrew; Porambo, Michael; McCall, Benjamin

    2011-06-01

    The technique of Cavity Enhanced Velocity Modulation Spectroscopy (CEVMS) has recently been developed. By demodulating the detector signal at twice the plasma modulation frequency (2f), the velocity-modulated ionic absorption signal can be extracted. Although the concentration-modulated excited neutral molecules are also observed at 2f, the ion and neutral signals can be distinguished and separated with phase-sensitive demodulation. The optical cavity provides two major benefits. It increases both the optical path length and the intracavity laser power by a factor of 2×Finesse/π. The multipass advantage allows for much longer path length than was previously possible with unidirectional multipass White cells. The power enhancement combined with perfectly overlapped counterpropagating beams within the cavity allows for sub-Doppler spectroscopy. Although CEVMS showed much potential, its sensitivity was ultimately limited by electronic noise from the plasma interfering with the cavity-locking electronics. We have further improved upon CEVMS by combining it with Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS). The laser is frequency modulated at precisely an integer multiple of the free spectral range of the optical cavity; this allows the heterodyne sidebands to be coupled into the optical cavity. Heterodyne detection of the cavity leak-out is immune to noise in the laser-cavity lock, and 2f demodulation further decreases electronic noise in the system and retains ion-neutral discrimination. The additional level of modulation beyond ordinary CEVMS has the added advantage of enabling the observation of both absorption and dispersion signals simultaneously by using two RF mixers, each driving its own lock-in amplifier. In a single scan, four distinct signals can be obtained: absorption and dispersion for ions and excited neutrals. The technique has been demonstrated in the near-IR for N_2^+. B. M. Siller, A. A. Mills and B. J. Mc

  2. New frontiers in time-domain diffuse optics, a review

    NASA Astrophysics Data System (ADS)

    Pifferi, Antonio; Contini, Davide; Mora, Alberto Dalla; Farina, Andrea; Spinelli, Lorenzo; Torricelli, Alessandro

    2016-09-01

    The recent developments in time-domain diffuse optics that rely on physical concepts (e.g., time-gating and null distance) and advanced photonic components (e.g., vertical cavity source-emitting laser as light sources, single photon avalanche diode, and silicon photomultipliers as detectors, fast-gating circuits, and time-to-digital converters for acquisition) are focused. This study shows how these tools could lead on one hand to compact and wearable time-domain devices for point-of-care diagnostics down to the consumer level and on the other hand to powerful systems with exceptional depth penetration and sensitivity.

  3. New frontiers in time-domain diffuse optics, a review.

    PubMed

    Pifferi, Antonio; Contini, Davide; Mora, Alberto Dalla; Farina, Andrea; Spinelli, Lorenzo; Torricelli, Alessandro

    2016-09-01

    The recent developments in time-domain diffuse optics that rely on physical concepts (e.g., time-gating and null distance) and advanced photonic components (e.g., vertical cavity source-emitting laser as light sources, single photon avalanche diode, and silicon photomultipliers as detectors, fast-gating circuits, and time-to-digital converters for acquisition) are focused. This study shows how these tools could lead on one hand to compact and wearable time-domain devices for point-of-care diagnostics down to the consumer level and on the other hand to powerful systems with exceptional depth penetration and sensitivity.

  4. Optical diagnostics in the oral cavity: an overview

    PubMed Central

    Wilder-Smith, P; Holtzman, J; Epstein, J; Le, A

    2014-01-01

    As the emphasis shifts from damage mitigation to disease prevention or reversal of early disease in the oral cavity, the need for sensitive and accurate detection and diagnostic tools become more important. Many novel and emergent optical diagnostic modalities for the oral cavity are becoming available to clinicians with a variety of desirable attributes including: (i) non-invasiveness, (ii) absence of ionizing radiation, (iii) patient-friendliness, (iv) real-time information (v) repeatability, and (vi) high-resolution surface and subsurface images. In this article, the principles behind optical diagnostic approaches, their feasibility and applicability for imaging soft and hard tissues, and their potential usefulness as a tool in the diagnosis of oral mucosal lesions, dental pathologies, and other dental applications will be reviewed. The clinical applications of light-based imaging technologies in the oral cavity and of their derivative devices will be discussed to provide the reader with a comprehensive understanding of emergent diagnostic modalities. PMID:20561224

  5. Augmentation of Cavity Optical Inspection by Replicas Without Performance Degradation

    SciTech Connect

    Ge, M.; Burk, D.; Hicks, D.; Wu, G.; Thompson, C.; Cooley, L.D.; /Fermilab

    2009-01-01

    Although cavity optical inspection systems provide a huge amount of qualitative information about surface features, the amount of quantitative topographic informa-tion is limited. Here, we report the use of silicone-based RTV for replicas and moldings that provide increased details of topographic data associated with the optical cavity images. Profilometry scans of the molds yield mi-crometer-scale details associated with equator weld struc-tures and weld pits. This confirms at least two different types of pits, one which is bowl-shaped, and one which has a small peak at the bottom. The contour information extracted from profilometry can be used to evaluate mechanisms by which pits and other features limit RF performance. We present calculations based on a con-formal transformation of the profiles above. We also show that application of the replica followed by rinsing does not adversely affect the cavity performance.

  6. Laser Pulse-Stretching Using Multiple Optical Ring-Cavities

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet; Lee, Chi-Ming (Technical Monitor)

    2002-01-01

    We describe a simple and passive nanosecond-long (ns-long) laser 'pulse-stretcher' using multiple optical ring-cavities. We present a model of the pulse-stretching process for an arbitrary number of optical ring-cavities. Using the model, we optimize the design of a pulse-stretcher for use in a spontaneous Raman scattering excitation system that avoids laser-induced plasma spark problems. From the optimized design, we then experimentally demonstrate and verify the model with a 3-cavity pulse-stretcher system that converts a 1000 mJ, 8.4 ns-long input laser pulse into an approximately 75 ns-long (FWHM) output laser pulse with a peak power reduction of 0.10X, and an 83% efficiency.

  7. Measurement of aerosol optical properties by cw cavity enhanced spectroscopy

    NASA Astrophysics Data System (ADS)

    Jie, Guo; Ye, Shan-Shan; Yang, Xiao; Han, Ye-Xing; Tang, Huai-Wu; Yu, Zhi-Wei

    2016-10-01

    The CAPS (Cavity Attenuated Phase shift Spectroscopy) system, which detects the extinction coefficients within a 10 nm bandpass centered at 532 nm, comprises a green LED with center wavelength in 532nm, a resonant optical cavity (36 cm length), a Photo Multiplier Tube detector, and a lock in amplifier. The square wave modulated light from the LED passes through the optical cavity and is detected as a distorted waveform which is characterized by a phase shift with respect to the initial modulation. Extinction coefficients are determined from changes in the phase shift of the distorted waveform of the square wave modulated LED light that is transmitted through the optical cavity. The performance of the CAPS system was evaluated by using measurements of the stability and response of the system. The minima ( 0.1 Mm-1) in the Allan plots show the optimum average time ( 100s) for optimum detection performance of the CAPS system. In the paper, it illustrates that extinction coefficient was correlated with PM2.5 mass (0.91). These figures indicate that this method has the potential to become one of the most sensitive on-line analytical techniques for extinction coefficient detection. This work aims to provide an initial validation of the CAPS extinction monitor in laboratory and field environments. Our initial results presented in this paper show that the CAPS extinction monitor is capable of providing state-of-the-art performance while dramatically reducing the complexity of optical instrumentation for directly measuring the extinction coefficients.

  8. Superradiant Topological Peierls Insulator inside an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Mivehvar, Farokh; Ritsch, Helmut; Piazza, Francesco

    2017-02-01

    We consider a spinless ultracold Fermi gas tightly trapped along the axis of an optical resonator and transversely illuminated by a laser closely tuned to a resonator mode. At a certain threshold pump intensity, the homogeneous gas density breaks a Z2 symmetry towards a spatially periodic order, which collectively scatters pump photons into the cavity. We show that this known self-ordering transition also occurs for low field seeking fermionic particles when the laser light is blue detuned to an atomic transition. The emergent superradiant optical lattice in this case is homopolar and possesses two distinct dimerizations. Depending on the spontaneously chosen dimerization, the resulting Bloch bands can have a nontrivial topological structure characterized by a nonvanishing Zak phase. In the case where the Fermi momentum is close to half of the cavity-mode wave number, a Peierls-like instability here creates a topological insulator with a gap at the Fermi surface, which hosts a pair of edge states. The topological features of the system can be nondestructively observed via the cavity output: the Zak phase of the bulk coincides with the relative phase between laser and cavity field, while the fingerprint of edge states can be observed as additional broadening in a well-defined frequency window of the cavity spectrum.

  9. Superradiant Topological Peierls Insulator inside an Optical Cavity.

    PubMed

    Mivehvar, Farokh; Ritsch, Helmut; Piazza, Francesco

    2017-02-17

    We consider a spinless ultracold Fermi gas tightly trapped along the axis of an optical resonator and transversely illuminated by a laser closely tuned to a resonator mode. At a certain threshold pump intensity, the homogeneous gas density breaks a Z_{2} symmetry towards a spatially periodic order, which collectively scatters pump photons into the cavity. We show that this known self-ordering transition also occurs for low field seeking fermionic particles when the laser light is blue detuned to an atomic transition. The emergent superradiant optical lattice in this case is homopolar and possesses two distinct dimerizations. Depending on the spontaneously chosen dimerization, the resulting Bloch bands can have a nontrivial topological structure characterized by a nonvanishing Zak phase. In the case where the Fermi momentum is close to half of the cavity-mode wave number, a Peierls-like instability here creates a topological insulator with a gap at the Fermi surface, which hosts a pair of edge states. The topological features of the system can be nondestructively observed via the cavity output: the Zak phase of the bulk coincides with the relative phase between laser and cavity field, while the fingerprint of edge states can be observed as additional broadening in a well-defined frequency window of the cavity spectrum.

  10. Optical complexity in external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Rondoni, Lamberto; Ariffin, M. R. K.; Varatharajoo, Renuganth; Mukherjee, Sayan; Palit, Sanjay K.; Banerjee, Santo

    2017-03-01

    In this article, the window based complexity and output modulation of a time delayed chaotic semiconductor laser (SL) model has been investigated. The window based optical complexity (OC), is measured by introducing the recurrence sample entropy (SampEn). The analysis has been done without and in the presence of external noise. The significant changes in the dynamics can be observed under induced noise with weak strength. It has also been found that there is a strong positive correlation between the output power and the complexity of the system with various sets of parameters. The laser intensity, as well as the OC can be increased with the incremental noise strength and the associated system parameters. Thus, optical complexity quantifies the system dynamics and its instabilities, since is strongly correlated with the laser outputs. This analysis can be applied to measure the laser instabilities and modulation of output power.

  11. Double diffusion in arbitrary porous cavity: Part II

    NASA Astrophysics Data System (ADS)

    Ahamad, N. Ameer; Kamangar, Sarfaraz; Salman Ahmed N., J.; Soudagar, Manzoor Elahi M.; Khan, T. M. Yunus

    2017-07-01

    Heat and mass transfer in porous medium is one of the fundamental topics of interest. The present article is dedicated to study the effect of a small block placed at center of left vertical surface of the cavity. The block is maintained at isothermal temperature That three of its edges attached with porous medium. The left surface of cavity is maintained at highest concentration and right surface at lowest concentration. The right surface of cavity is at cold isothermal temperature Tc. Governing equations are converted into matrix form of equations with the help of finite element method and solved iteratively by using a computer code generated in MATLAB.

  12. Noise-Immune Cavity-Enhanced Optical Frequency Comb Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rutkowski, Lucile; Khodabakhsh, Amir; Johanssson, Alexandra C.; Foltynowicz, Aleksandra

    2015-06-01

    We present noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), a recently developed technique for sensitive, broadband, and high resolution spectroscopy. In NICE-OFCS an optical frequency comb (OFC) is locked to a high finesse cavity and phase-modulated at a frequency precisely equal to (a multiple of) the cavity free spectral range. Since each comb line and sideband is transmitted through a separate cavity mode in exactly the same way, any residual frequency noise on the OFC relative to the cavity affects each component in an identical manner. The transmitted intensity contains a beat signal at the modulation frequency that is immune to frequency-to-amplitude noise conversion by the cavity, in a way similar to continuous wave noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS). The light transmitted through the cavity is detected with a fast-scanning Fourier-transform spectrometer (FTS) and the NICE-OFCS signal is obtained by fast Fourier transform of the synchronously demodulated interferogram. Our NICE-OFCS system is based on an Er:fiber femtosecond laser locked to a cavity with a finesse of ˜9000 and a fast-scanning FTS equipped with a high-bandwidth commercial detector. We measured NICE-OFCS signals from the 3νb{1}+νb{3} overtone band of CO_2 around 1.57 μm and achieved absorption sensitivity 6.4×10-11cm-1 Hz-1/2 per spectral element, corresponding to a minimum detectable CO_2 concentration of 25 ppb after 330 s integration time. We will describe the principles of the technique and its technical implementation, and discuss the spectral lineshapes of the NICE-OFCS signals. A. Khodabakhsh, C. Abd Alrahman, and A. Foltynowicz, Opt. Lett. 39, 5034-5037 (2014). J. Ye, L. S. Ma, and J. L. Hall, J. Opt. Soc. Am. B 15, 6-15 (1998). A. Khodabakhsh, A. C. Johansson, and A. Foltynowicz, Appl. Phys. B (2015) doi:10.1007/s00340-015-6010-7.

  13. Investigations of a Coherently Driven Semiconductor Optical Cavity QED System

    DTIC Science & Technology

    2008-09-30

    is performed through use of a 980 nm band external cavity tunable diode laser as a pump source Fig. 2a. The pump laser emission is directed into...coherent optical probing with a 1300 nm tunable laser solid lines and optical pumping with a 980 nm pump laser dashed lines. Optical component acronyms...recording the transmitted signal with an InGaAs avalanche photodiode APD. The pump laser is fixed on-resonance with a WGM which typically has a Q limited

  14. Modes of a twisted optical cavity

    SciTech Connect

    Habraken, Steven J. M.; Nienhuis, Gerard

    2007-03-15

    An astigmatic optical resonator consists of two astigmatic mirrors facing each other. The resonator is twisted when the symmetry axes of the mirrors are nonparallel. We present an algebraic method to obtain the complete set of the paraxial eigenmodes of such a resonator. Basic ingredients are the complex eigenvectors of the four-dimensional transfer matrix that describes the transformation of a ray of light over a roundtrip of the resonator. The relation between the fundamental mode and the higher-order modes is expressed in terms of raising operators in the spirit of the ladder operators of the quantum harmonic oscillator.

  15. Time-domain diffuse optics: towards next generation devices

    NASA Astrophysics Data System (ADS)

    Contini, Davide; Dalla Mora, Alberto; Arridge, Simon; Martelli, Fabrizio; Tosi, Alberto; Boso, Gianluca; Farina, Andrea; Durduran, Turgut; Martinenghi, Edoardo; Torricelli, Alessandro; Pifferi, Antonio

    2015-07-01

    Diffuse optics is a powerful tool for clinical applications ranging from oncology to neurology, but also for molecular imaging, and quality assessment of food, wood and pharmaceuticals. We show that ideally time-domain diffuse optics can give higher contrast and a higher penetration depth with respect to standard technology. In order to completely exploit the advantages of a time-domain system a distribution of sources and detectors with fast gating capabilities covering all the sample surface is needed. Here, we present the building block to build up such system. This basic component is made of a miniaturised source-detector pair embedded into the probe based on pulsed Vertical-Cavity Surface-Emitting Lasers (VCSEL) as sources and Single-Photon Avalanche Diodes (SPAD) or Silicon Photomultipliers (SiPM) as detectors. The possibility to miniaturized and dramatically increase the number of source detectors pairs open the way to an advancement of diffuse optics in terms of improvement of performances and exploration of new applications. Furthermore, availability of compact devices with reduction in size and cost can boost the application of this technique.

  16. Suppressing spectral diffusion of emitted photons with optical pulses

    SciTech Connect

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; Dobrovitski, V. V.

    2016-01-22

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1 ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.

  17. Fiber Optic Based Thermometry System for Superconducting RF Cavities

    SciTech Connect

    Kochergin, Vladimir

    2013-05-06

    Thermometry is recognized as the best technique to identify and characterize losses in SRF cavities. The most widely used and reliable apparatus for temperature mapping at cryogenic temperatures is based on carbon resistors (RTDs). The use of this technology on multi-cell cavities is inconvenient due to the very large number of sensors required to obtain sufficient spatial resolution. Recent developments make feasible the use of multiplexible fiber optic sensors for highly distributed temperature measurements. However, sensitivity of multiplexible cryogenic temperature sensors was found extending only to 12K at best and thus was not sufficient for SRF cavity thermometry. During the course of the project the team of MicroXact, JLab and Virginia Tech developed and demonstrated the multiplexible fiber optic sensor with adequate response below 20K. The demonstrated temperature resolution is by at least a factor of 60 better than that of the best multiplexible fiber optic temperature sensors reported to date. The clear path toward at least 10times better temperature resolution is shown. The first to date temperature distribution measurements with ~2.5mm spatial resolution was done with fiber optic sensors at 2K to4K temperatures. The repeatability and accuracy of the sensors were verified only at 183K, but at this temperature both parameters significantly exceeded the state of the art. The results of this work are expected to find a wide range of applications, since the results are enabling the whole new testing capabilities, not accessible before.

  18. Microfabricated Optical Cavities and Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Lončar, Marko; Scherer, Axel

    Microfabricated periodic structures with a high refractive index contrast have recently become very interesting geometries for the manipulation of light. The existence of a photonic bandgap, a frequency range within which propagation of light is prevented in all directions, is very useful where spatial localization of light is required. Ideally, by constructing three-dimensional confinement geometries, light propagation can be controlled in all three dimensions. However, since the fabrication of 3D photonic crystals is difficult, a more manufacturable approach is based on the use of one- or two-dimensional geometries. Here we describe the evolution of microcavities from 1D Bragg reflectors to 2D photonic crystals. The 1D microcavity laser (VCSEL) has already found widespread commercial use in data communications, and the equivalent 2D geometry has recently attracted a lot of research attention. 2D photonic crystal lasers, fabricated within a thin dielectric membrane and perforated with a two-dimensional lattice of holes, are very appealing for dense integration of photonic devices in telecommunications and optical sensing systems. In this chapter, we describe theory and experiments of planar photonic crystals as well as their applications towards lasers and super-dispersive elements. Low-threshold 2D photonic crystal lasers were recently demonstrated both in air and in different chemical solutions and can now be used to perform spectroscopic tests on ultra-small volumes of analyte.

  19. Optomechanical damping of a nanomembrane inside an optical ring cavity

    NASA Astrophysics Data System (ADS)

    Yilmaz, Arzu; Schuster, Simon; Wolf, Philip; Schmidt, Dag; Eisele, Max; Zimmermann, Claus; Slama, Sebastian

    2017-01-01

    We experimentally and theoretically investigate mechanical nanooscillators coupled to the light in an optical ring resonator made of dielectric mirrors. We identify an optomechanical damping mechanism that is fundamentally different to the well known cooling in standing wave cavities. While in a standing wave cavity the mechanical oscillation shifts the resonance frequency of the cavity, in a ring resonator the frequency does not change. Instead the position of the nodes is shifted with the mechanical excursion. We derive the damping rates and test the results experimentally with a silicon-nitride nanomembrane. It turns out that scattering from small imperfections of the dielectric mirror coatings has to be taken into account to explain the value of the measured damping rate. We extend our theoretical model and consider a second reflector in the cavity that captures the effects of mirror back scattering. This model can be used to also describe the situation of two membranes that both interact with the cavity fields. This may be interesting for future work on synchronization of distant oscillators that are coupled by intracavity light fields.

  20. Biosensors based on GaN nanoring optical cavities

    NASA Astrophysics Data System (ADS)

    Kouno, Tetsuya; Takeshima, Hoshi; Kishino, Katsumi; Sakai, Masaru; Hara, Kazuhiko

    2016-05-01

    Biosensors based on GaN nanoring optical cavities were demonstrated using room-temperature photoluminescence measurements. The outer diameter, height, and thickness of the GaN nanorings were approximately 750-800, 900, and 130-180 nm, respectively. The nanorings functioned as whispering-gallery-mode (WGM)-type optical cavities and exhibited sharp resonant peaks like lasing actions. The evanescent component of the WGM was strongly affected by the refractive index of the ambient environment, the type of liquid, and the sucrose concentration of the analyzed solution, resulting in shifts of the resonant wavelengths. The results indicate that the GaN nanorings can potentially be used in sugar sensors of the biosensors.

  1. Weyl semimetal phases and implementation in degenerate optical cavities

    NASA Astrophysics Data System (ADS)

    Sun, Bo Ye; Luo, Xi Wang; Gong, Ming; Guo, Guang Can; Zhou, Zheng Wei

    2017-07-01

    We propose a scheme for simulating the behaviors of Weyl semimetals by using a two-dimensional array of degenerate optical cavities. To simplify such a three-dimensional system to a two-dimension system, the orbital angular momentum of the light is used to support an extra synthetic dimension. We find that this system is quite suitable for the purpose of investigating the features of the Weyl point by taking advantage of the input-output relation of the optical cavity system. We show that the transport properties of our system are determined by the number of sites along the constrained direction and the spin texture of the system makes the transport momentum dependent and spin dependent.

  2. Surface diffusion studies by optical diffraction techniques

    SciTech Connect

    Xiao, X.D.

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect.

  3. Surface diffusion studies by optical diffraction techniques

    SciTech Connect

    Xiao, Xu -Dong

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect.

  4. Double diffusion in arbitrary porous cavity: Part III

    NASA Astrophysics Data System (ADS)

    Ahamad, N. Ameer; Salman Ahmed N., J.; Kamangar, Sarfaraz; Khan, T. M. Yunus; Soudagar, Manzoor Elahi M.

    2017-07-01

    Investigation of heat and mass transfer in a porous cavity is carried out with respect to a small block placed at top corner of cavity along its left vertical surface. The block is heated isothermally to temperature Th and right vertical surface is maintained at isothermal temperature Tc. The left vertical surface is maintained at constant concentration Ch and right vertical surface at Cc such that Ch>Cc. The governing equations are non-dimensionalised and converted into simpler form of algebraic equations to facilitate its solution. It is found that the heat and mass transfer behaviour is substantially different from the case of block placed at bottom or at the center of left vertical surface.

  5. Nonlinear optics in organic cavity polaritons (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Singer, Kenneth D.; Liu, Bin; Crescimanno, Michael; Twieg, Robert J.

    2017-02-01

    Coupling between excitons belonging to organic dyes and photons in a microcavities forming cavity polaritons have been receiving attention for their fundamental interest as well as potential applications in coherent light sources. Organic materials are of particular interest as the coupling is particularly strong due to the large oscillator strength of conjugated organic molecules. The resulting coupling in organic materials is routinely in the strong regime. Ultrastrong coupling between photons and excitons in microcavities containing organic dyes and semiconductors has been recently observed in room temperature. We have studied the coupling between cavity pairs in the ultrastrong regime and found that the high order terms in the modified Jaynes-Cummings model result in broken degeneracy between the symmetric and antisymmetric modes. The unusually strong coupling between cavity photons and organic excitons dovetail with the robust nonlinear optical responses of the same materials. This provides a new and promising hybrid material for photonics. We report on measurements of photorefraction in organic cavities containing a derivative of the photorefractive organic glass based on 2-dicyanomethylene-3-cyano-2,5-dihydrofuran (DCDHF).

  6. Mode-by-mode optical feedback: cavity ringdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Motto-Ros, V.; Morville, J.; Rairoux, P.

    2007-05-01

    We describe a new continuous wave cavity ringdown spectroscopy (cw-CRDS) approach using an extended cavity diode laser (ECDL) optically self-locked to a high finesse cavity including an intracavity glass plate under the Brewster angle. Low noise, mode-by-mode absorption spectra are recorded at a high acquisition rate (laser frequency scan greater than 400 GHz/s) and covering four orders of magnitude in absorption coefficient. Sampling spectra with the fixed high finesse cavity frequency comb provides high precision frequency markers. An original scheme for the laser beam shut-down, based on signal shape analysis and the diode laser injection current control, is presented. This scheme avoids any supplementary switching device. To retrieve ringdown processing at a kilohertz rate several exponential decay fit algorithms are compared. Performances of this new scheme are demonstrated with the observation of very weak lines of the oxygen B-band around 680 nm. Atmospheric spectra of isolated lines averaged for less than 10 s show a baseline noise of 5×10-10 cm-1 and a single point minimum detectable absorption loss over a one-second measurement interval of 2×10-10 cm/sqrt{text{Hz}} is obtained.

  7. Nonperturbative atom-photon interactions in an optical cavity

    SciTech Connect

    Carmichael, H.J.; Tian, L.; Ren, W.

    1994-12-31

    One of the principal developments in cavity quantum electrodynamics in the last few years has been the extension of the ideas originally applied to systems of Rydberg atoms in microwave cavities to optical frequencies. As a corollary of this, more attention is being paid to quantum fluctuations and photon statistics. Another development, still in its infancy, is a move toward experiments using slowed or trapped atoms, or velocity selected beams; these methods are needed to enter the nonperturbative (strong dipole coupling) regime for one atom where there are experiments on subtle quantum-statistical effects go carry out. In this chapter we solve a number of theoretical problems related to these themes. Although the focus of the work is on optical systems, most of what we do is also relevant at microwave frequencies. We emphasize quantum fluctuations and photon statistics, and we try always to separate the quantum physics from those aspects of the physics that are understandable in classical terms. On the whole we only pay attention to the nonperturbative regime of cavity quantum electrodynamics where the dipole coupling strength is larger than the dissipation rates. 59 refs., 14 figs.

  8. External folded cavity optical feedback diode laser with megahertz relative linewidth

    NASA Astrophysics Data System (ADS)

    Luo, Zhifu; Long, Xingwu; Tan, Zhongqi

    2014-12-01

    We present a extended-cavity diode laser (ECDL) with megahertz linewidth by optical feedback from a folded Fabry-Perot cavity, and demonstrate the efficient laser linewidth reduction and frequency stabilization of the optical feedback technique. In our experiments, a folded Fabry-Perot cavity with a finesse of 4750 replaces the reflecting mirror in the traditional ECDL configuration, the folded Fabry-Perot cavity can serve as an optical feedback element, which forces the semiconductor laser automatically to lock its frequency optically to the cavity resonance frequency. The laser's phase noise is significantly suppressed, and The laser's linewidth is reduced from about 20GHz to 15MHz.

  9. Nonlinear Optics and Wavelength Translation Via Cavity-Optomechanics

    NASA Astrophysics Data System (ADS)

    Hill, Jeffrey Thomas

    The field of cavity-optomechanics explores the interaction of light with sound in an ever increasing array of devices. This interaction allows the mechanical system to be both sensed and controlled by the optical system, opening up a wide variety of experiments including the cooling of the mechanical resonator to its quantum mechanical ground state and the squeezing of the optical field upon interaction with the mechanical resonator, to name two. In this work we explore two very different systems with different types of optomechanical coupling. The first system consists of two microdisk optical resonators stacked on top of each other and separated by a very small slot. The interaction of the disks causes their optical resonance frequencies to be extremely sensitive to the gap between the disks. By careful control of the gap between the disks, the optomechanical coupling can be made to be quadratic to first order which is uncommon in optomechanical systems. With this quadratic coupling the light field is now sensitive to the energy of the mechanical resonator and can directly control the potential energy trapping the mechanical motion. This ability to directly control the spring constant without modifying the energy of the mechanical system, unlike in linear optomechanical coupling, is explored. Next, the bulk of this thesis deals with a high mechanical frequency optomechanical crystal which is used to coherently convert photons between different frequencies. This is accomplished via the engineered linear optomechanical coupling in these devices. Both classical and quantum systems utilize the interaction of light and matter across a wide range of energies. These systems are often not naturally compatible with one another and require a means of converting photons of dissimilar wavelengths to combine and exploit their different strengths. Here we theoretically propose and experimentally demonstrate coherent wavelength conversion of optical photons using photon

  10. Cavity quantum electro-optics. II. Input-output relations between traveling optical and microwave fields

    NASA Astrophysics Data System (ADS)

    Tsang, Mankei

    2011-10-01

    In a previous paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.81.063837 81, 063837 (2010)], I proposed a quantum model of the cavity electro-optic modulator, which can coherently couple an optical cavity mode to a microwave resonator mode and enable quantum operations on the two modes, including laser cooling of the microwave resonator, electro-optic entanglement, and backaction-evading optical measurement of a microwave quadrature. In this sequel, I focus on the quantum input-output relations between traveling optical and microwave fields coupled to the cavity electro-optic modulator. With red-sideband optical pumping, the relations are shown to resemble those of a beam splitter for the traveling fields, so that in the ideal case of zero parasitic loss and critical coupling, microwave photons can be coherently up converted to “flying” optical photons with unit efficiency, and vice versa. With blue-sideband pumping, the modulator acts as a nondegenerate parametric amplifier, which can generate two-mode squeezing and hybrid entangled photon pairs at optical and microwave frequencies. These fundamental operations provide a potential bridge between circuit quantum electrodynamics and quantum optics.

  11. Cavity quantum electro-optics. II. Input-output relations between traveling optical and microwave fields

    SciTech Connect

    Tsang, Mankei

    2011-10-15

    In a previous paper [Phys. Rev. A 81, 063837 (2010)], I proposed a quantum model of the cavity electro-optic modulator, which can coherently couple an optical cavity mode to a microwave resonator mode and enable quantum operations on the two modes, including laser cooling of the microwave resonator, electro-optic entanglement, and backaction-evading optical measurement of a microwave quadrature. In this sequel, I focus on the quantum input-output relations between traveling optical and microwave fields coupled to the cavity electro-optic modulator. With red-sideband optical pumping, the relations are shown to resemble those of a beam splitter for the traveling fields, so that in the ideal case of zero parasitic loss and critical coupling, microwave photons can be coherently up converted to ''flying'' optical photons with unit efficiency, and vice versa. With blue-sideband pumping, the modulator acts as a nondegenerate parametric amplifier, which can generate two-mode squeezing and hybrid entangled photon pairs at optical and microwave frequencies. These fundamental operations provide a potential bridge between circuit quantum electrodynamics and quantum optics.

  12. Enhancement in Quality Factor of SRF Niobium Cavities by Material Diffusion

    SciTech Connect

    Dhakal, Pashupati; Ciovati, Gianluigi; Kneisel, Peter K.; Myneni, Ganapati Rao

    2015-06-01

    An increase in the quality factor of superconducting radiofrequency cavities is achieved by minimizing the surface resistance during processing steps. The surface resistance is the sum of temperature independent residual resistance and temperature/material dependent Bardeen-Cooper-Schrieffer (BCS) resistance. High temperature heat treatment usually reduces the impurities concentration from the bulk niobium, lowering the residual resistance. The BCS part can be reduced by selectively doping non-magnetic impurities. The increase in quality factor, termed as Q-rise, was observed in cavities when titanium or nitrogen thermally diffused in the inner cavity surface.

  13. Optical and electrical mappings of surface plasmon cavity modes

    NASA Astrophysics Data System (ADS)

    Ye, Fan; Merlo, Juan M.; Burns, Michael J.; Naughton, Michael J.

    2014-04-01

    Plasmonics is a rapidly expanding field, founded in physics but now with a growing number of applications in biology (biosensing), nanophotonics, photovoltaics, optical engineering and advanced information technology. Appearing as charge density oscillations along a metal surface, excited by electromagnetic radiation (e.g., light), plasmons can propagate as surface plasmon polaritons, or can be confined as standing waves along an appropriately-prepared surface. Here, we review the latter manifestation, both their origins and the manners in which they are detected, the latter dominated by near field scanning optical microscopy (NSOM/SNOM). We include discussion of the "plasmonic halo" effect recently observed by the authors, wherein cavity-confined plasmons are able to modulate optical transmission through step-gap nanostructures, yielding a novel form of color (wavelength) selection.

  14. Coupling a single trapped atom to a nanoscale optical cavity.

    PubMed

    Thompson, J D; Tiecke, T G; de Leon, N P; Feist, J; Akimov, A V; Gullans, M; Zibrov, A S; Vuletić, V; Lukin, M D

    2013-06-07

    Hybrid quantum devices, in which dissimilar quantum systems are combined in order to attain qualities not available with either system alone, may enable far-reaching control in quantum measurement, sensing, and information processing. A paradigmatic example is trapped ultracold atoms, which offer excellent quantum coherent properties, coupled to nanoscale solid-state systems, which allow for strong interactions. We demonstrate a deterministic interface between a single trapped rubidium atom and a nanoscale photonic crystal cavity. Precise control over the atom's position allows us to probe the cavity near-field with a resolution below the diffraction limit and to observe large atom-photon coupling. This approach may enable the realization of integrated, strongly coupled quantum nano-optical circuits.

  15. Three-dimensional nanometer-scale optical cavities of indefinite medium

    PubMed Central

    Yao, Jie; Yang, Xiaodong; Yin, Xiaobo; Bartal, Guy; Zhang, Xiang

    2011-01-01

    Miniaturization of optical cavities has numerous advantages for enhancing light–matter interaction in quantum optical devices, low-threshold lasers with minimal power consumption, and efficient integration of optoelectronic devices at large scale. However, the realization of a truly nanometer-scale optical cavity is hindered by the diffraction limit of the nature materials. In addition, the scaling of the photon life time with the cavity size significantly reduces the quality factor of small cavities. Here we theoretically present an approach to achieve ultrasmall optical cavities using indefinite medium with hyperbolic dispersion, which allows propagation of electromagnetic waves with wave vectors much larger than those in vacuum enabling extremely small 3D cavity down to (λ/20)3. These cavities exhibit size-independent resonance frequencies and anomalous scaling of quality factors in contrast to the conventional cavities, resulting in nanocavities with both high Q/Vm ratio and broad bandwidth. PMID:21709266

  16. Thermal Wave Resonator Cavity Applied to the Study of the Thermal Diffusivity of Coffee Infusions

    NASA Astrophysics Data System (ADS)

    Tepepa, B. Briseño; Marín, E.; Martín-Martínez, E. San; Orea, A. Cruz

    2009-10-01

    Among the photothermal methods, the photopyroelectric technique, in its several experimental configurations, has been extensively used to measure the thermal properties of liquids, mainly the thermal effusivity and diffusivity. In this paper, the use of the so-called thermal wave resonator cavity method, in the cavity-length-scan mode, to measure the thermal diffusivity of commercial coffee infusions with samples at different concentrations and degrees of degradation induced by heating cycles is reported. A linear relationship between the logarithm of the pyroelectric signal amplitude and the sample thickness was observed, in agreement with the basic theory for the experimental configuration used here, from which the thermal diffusivity values of the samples were obtained. The thermal diffusivity was found to be almost independent of the coffee concentration in water but that this parameter is sensitive to sample modifications induced by degradation. This work represents another step to demonstrate the capability of the used method for characterization of the thermal properties of liquids.

  17. Compact carbon monoxide sensor utilizing a confocal optical cavity.

    NASA Technical Reports Server (NTRS)

    Scott, B.; Magyar, J.; Weyant, R.; Hall, J.

    1973-01-01

    The carbon monoxide sensor discussed in this paper utilizes a unique confocal cavity which allows the complete system to be packaged in a small volume suitable for hand-held use. The optical system is the heart of the instrument with equal emphasis placed on the electronics support circuitry, consisting essentially of a thermal infrared pyroelectric detector and lock-in amplifier. The pyroelectric detector offers a major advantage over other thermal detectors, providing a signal-to-noise ratio and detectivity that remain nearly constant over the frequency range from dc to 2000 Hz. Since bias voltage is not required, low frequency noise is not generated in the detector.

  18. Compact carbon monoxide sensor utilizing a confocal optical cavity.

    NASA Technical Reports Server (NTRS)

    Scott, B.; Magyar, J.; Weyant, R.; Hall, J.

    1973-01-01

    The carbon monoxide sensor discussed in this paper utilizes a unique confocal cavity which allows the complete system to be packaged in a small volume suitable for hand-held use. The optical system is the heart of the instrument with equal emphasis placed on the electronics support circuitry, consisting essentially of a thermal infrared pyroelectric detector and lock-in amplifier. The pyroelectric detector offers a major advantage over other thermal detectors, providing a signal-to-noise ratio and detectivity that remain nearly constant over the frequency range from dc to 2000 Hz. Since bias voltage is not required, low frequency noise is not generated in the detector.

  19. Bloch FDTD simulation of slow optical wave resonance cavity in optical storage technology

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Lin, Zhaohua; Cai, Lihua

    2013-08-01

    Long chain series resonance cavity is suitable for transferring slow optical wave, which can be served as the basic device for optical storage technology. Micro-ring resonator is one kind of such a long chain structure, which is considered to be the basic component of optical integrated circuit and optical computer in the future. The discrete energy level has the potential to distinguish digital optical data. The optical delay characteristics make such a device possible to store the information for some time. The advantage of this device is that it has the potential to construct an optical storage device in small geometrical dimension and could use mature semiconductor manufacture capability to lower the design and manufacturing expenses. Many experimental results have proved a lot of material and geometrical coefficients are very important for such an optical delay device. New theory method is needed to calculate the periodical energy transfer and time delay characteristics, which can be compared with experimental result. The Bloch FDTD is presented for analysis of such a new optical device, based on the optical Bloch energy band theory. The energy band characteristics of micro-ring periodical optical waveguide device is discussed used that analytical method. This precise calculated method could be served as a useful tool for design the structure of such resonance cavity to achieve desired slow optical wave transfer performance.

  20. Blood oxygenation monitoring by diffuse optical tomography

    SciTech Connect

    Patachia, M; Dutu, D.C.A.; Dumitras, D.C.

    2011-01-24

    Diffuse optical tomography (DOT) makes it possible to reconstruct, in two or three dimensions, the internal structure of the biological tissues based on the distribution of the absorption coefficient and the reduced scattering coefficient, using optical measurements at multiple source - detector positions on the tissue surface. The measurement of the light intensity transmitted through the tissue can be also used to compute the haemoglobin and oxyhaemoglobin concentrations, measuring the selective absorption of the main blood chromophores by near infrared spectroscopy (NIRS). The spectral selectivity of the system and the evaluation of the blood volume and blood oxygenation (BV and OXY distributions), together with the reconstruction of the inner structure of the tissue, can improve the accuracy of early cancer diagnosis, based on the tissue angiogenesis characterisation. (application of lasers and laser-optical methods in life sciences)

  1. Mammogram-based diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Chiang, Hung-Chih; Yu, Jhao-Ming; Chen, Liang-Yu; Pan, Min-Cheng; Sun, Sheng-Yih; Chou, Chia-Cheng; Pan, Min-Chun

    2012-03-01

    The study aims at developing an optical measurement module incorporated with an X-ray mammographic system to obtain diffuse optical images (DOI) for the detection of breast tumors. Two goals steer the study: (1) to enhance sensitivity and specificity of tumor detection through the use of functional DOI; and (2) to reduce radiation exposure by using only one mammogram, instead of two, as structure information to compute optical-coefficient images. A dual-direction (downward and upward) scanning device to project illuminated near infrared light with multiple-channel switching for both sources and detectors was designed and constructed to obtain double information. The designed and constructed NIR scanning module incorporates with GE Senographe 2000D to assist breast tumor detection.

  2. Optical heterodyne detection for cavity ring-down spectroscopy

    DOEpatents

    Levenson, Marc D.; Paldus, Barbara A.; Zare, Richard N.

    2000-07-25

    A cavity ring-down system for performing cavity ring-down spectroscopy (CRDS) using optical heterodyne detection of a ring-down wave E.sub.RD during a ring-down phase or a ring-up wave E.sub.RU during a ring up phase. The system sends a local oscillator wave E.sub.LO and a signal wave E.sub.SIGNAL to the cavity, preferably a ring resonator, and derives an interference signal from the combined local oscillator wave E.sub.LO and the ring-down wave E.sub.RD (or ring-up wave E.sub.RU). The local oscillator wave E.sub.LO has a first polarization and the ring-down wave E.sub.RD has a second polarization different from the first polarization. The system has a combining arrangement for combining or overlapping local oscillator wave E.sub.LO and the ring-down wave E.sub.RD at a photodetector, which receives the interference signal and generates a heterodyne current I.sub.H therefrom. Frequency and phase differences between the waves are adjustable.

  3. Observation of optically induced transparency in a micro-cavity

    NASA Astrophysics Data System (ADS)

    Zheng, Yuanlin; Cao, Jianjun; Wan, Wenjie

    2016-03-01

    We report on the observation of optically induced transparency (OIT) in a compact microresonator in an ambient environment by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity. Its optical-controlling capacity and non-reciprocity characteristics at the transparency windows are also demonstrated. Active-controlling of the OIT can be achieved by varying a strong pump beam, while a small frequency-detuning of the pump can lead to a Fano-like asymmetric resonance justifying the interference nature of OIT. Furthermore, OIT observed here is a non-reciprocal one, since FWM gain is a unidirectional one owing to the conservation law of momentum.

  4. Cavity opto-mechanics using an optically levitated nanosphere

    PubMed Central

    Chang, D. E.; Regal, C. A.; Papp, S. B.; Wilson, D. J.; Ye, J.; Painter, O.; Kimble, H. J.; Zoller, P.

    2010-01-01

    Recently, remarkable advances have been made in coupling a number of high-Q modes of nano-mechanical systems to high-finesse optical cavities, with the goal of reaching regimes in which quantum behavior can be observed and leveraged toward new applications. To reach this regime, the coupling between these systems and their thermal environments must be minimized. Here we propose a novel approach to this problem, in which optically levitating a nano-mechanical system can greatly reduce its thermal contact, while simultaneously eliminating dissipation arising from clamping. Through the long coherence times allowed, this approach potentially opens the door to ground-state cooling and coherent manipulation of a single mesoscopic mechanical system or entanglement generation between spatially separate systems, even in room-temperature environments. As an example, we show that these goals should be achievable when the mechanical mode consists of the center-of-mass motion of a levitated nanosphere. PMID:20080573

  5. [APPROACH TO ESTABLISHMENT OF INDICATIONS FOR PROGRAMMED SANATION OF ABDOMINAL CAVITY IN DIFFUSE PERITONITIS].

    PubMed

    Joffe, I V; Lesnoy, V V

    2016-01-01

    The results of treatment of 33 patients, suffering diffuse peritonitis, with postoperatively applied tactics of the programmed surgical sanation of abdominal cavity were analyzed. Indications for relaparotomy were established, based on the estimation scale for the enteral insufficiency severity. The patients death and the complications causes were analyzed, depending on terms and rates of relaparotomy conduction.

  6. Models for coupled diffusive/strain controlled growth of creep cavities

    SciTech Connect

    Lu, H.M.; Delph, T.J. )

    1993-08-01

    The importance of intergranular creep cavitation to high-temperature failure processes in metals and ceramics has been well-recognized for some time now. In general, creep cavity growth at elevated temperature is thought to occur by one of two processes. The first of these is diffusive growth, whereby matter is transported from the cavity surface and is deposited on the grain boundary. The second is strain-controlled growth, in which the cavity grows entirely as a consequence of creep deformation of the surrounding material under the action of an applied stress. Several models of cavity growth have been proposed in which these processes are coupled to each other and occur simultaneously. These models have attained some currency and have been used in several studies involving the growth of creep cavitation. The purpose of the present note is to investigate in some detail one particular class of these models.

  7. Diffuse optical-MRI fusion and applications

    NASA Astrophysics Data System (ADS)

    Lesage, F.; Gagnon, L.; Dehaes, M.

    2008-02-01

    Diffuse optical imaging (DOI) is a relatively new functional imaging modality offering the possibility to record changes in hemoglobin concentrations. It is based on the propagation of near-infrared light through biological tissues. By measuring the optical absorption of the blood in the cortex, DOI enables the estimation of changes of deoxy-hemoglobin (HbR) and oxy-hemoglobin (HbO II) concentrations. It thus provides indirect information on neuronal activity. Drawbacks of optical imaging are its lack of quantification abilities as well as poor spatial resolution. Although not much can be done concerning the second issue, diffusion being the limiting factor, one can aim at more quantitative data by the use of extra information. As an example, the determination of baseline concentrations done by fitting a temporal or frequency curve to recover background concentrations is not expected to be accurate due to the heterogeneity of the underlying tissues. The vascular architecture, unknown when doing DOI alone, also plays a significant role in the signal detected. Partial volume effects due to an optode pair overlapping a large vein will lead to confounding data and create difficulties in analyzing the neuronal activation. Here we show that fusion with MRI, but done outside the scanner, may help solving some of these issues.

  8. Optical cavity temperature measurement based on the first overtones spontaneous emission spectra for HF chemical laser

    NASA Astrophysics Data System (ADS)

    Tang, Shukai; Li, Liucheng; Duo, Liping; Wang, Yuanhu; Yu, Haijun; Jin, Yuqi; Sang, Fengting

    2015-02-01

    An optical cavity temperature test method has been established for the HF chemical laser. This method assumes that in HF optical cavity the rotational distribution of vibrationally excited HF molecules meets the statistical thermodynamic distribution, the first overtones (v = 3-1 and 2-0) spontaneous emission spectral intensity distribution is obtained by using OMA V, the optical cavity temperature is calculated by linear fitting the rotational thermal equilibrium distribution formula for each HF vibrationally excited state. This method is simple, reliable, and repeatable. This method can be used to test the optical cavity temperature not only without lasing, but also with lasing.

  9. Assessing PDT response with diffuse optical spectroscopies

    NASA Astrophysics Data System (ADS)

    Rohrbach, Daniel J.

    Photodynamic therapy (PDT) is used to treat a variety of conditions including cancer. Effective PDT requires three components: a photosensitizer (PS), light of a specific wavelength to activate the PS and oxygen. When all three are present in a lesion it leads to cell death and vascular destruction. Optical techniques such as diffuse reflectance spectroscopy (DRS), diffuse fluorescence spectroscopy (DFS) and diffuse correlation spectroscopy (DCS) can be used to quantify vascular parameters and photosensitizer content before and after PDT, providing valuable information for assessing response. For the quantification of vascular parameters, a probe-specific empirical light transport model was developed. A look-up-table was constructed using tissue simulating phantoms made of Intralipid to control the scattering, India Ink to control the absorption and water. The empirical model allowed the quantification of optical properties as well as the vascular parameters blood volume fraction (BVf) and blood oxygen saturation (SO2) with DRS. Blood flow was measured using DCS. For the quantification of PS content two techniques were used. DRS was used to fit the absorption of the PS and DFS measured the fluorescence of the PS. For quantification of PS content from measured fluorescence, a correction factor was developed using Monte Carlo simulations to account for the optical properties at the excitation and emission wavelengths. The three techniques were used to assess PDT response in pre-clinical and clinical studies. For the preclinical study, mice were treated with HPPH-PDT and blood flow was measured continuously with DCS. Blood flow variables were compared to STAT3 crosslinking (a molecular marker for PDT photoreaction) and CD31 staining (to visualize intact endothelial cells after PDT). For the clinical study, patients in a clinical trial for HPPH-PDT were measured with DRS, DFS and DCS before and after treatment. Multiple parameters were compared to the clinical response

  10. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1996-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy.

  11. Coupling of Solute Vibrational Modes with a Fabry-Perot Optical Cavity Mode

    NASA Astrophysics Data System (ADS)

    Dunkelberger, Adam; Compton, Ryan; Fears, Kenan; Spann, Bryan; Long, James; Simpkins, Blake; Owrutsky, Jeffrey

    2015-03-01

    Electronic transitions of systems confined in optical microcavities can strongly couple to cavity modes, giving rise to new, mixed-character modes. Recent studies have demonstrated similar coherent coupling between the vibrational modes of a thin polymer film and a Fabry-Perot optical cavity mode. This coupling manifests experimentally as a splitting of the transmissive cavity mode into two dispersive branches separated by the vacuum Rabi splitting. Here we present recent experimental results for the coupling of solution-phase compounds with an optical cavity. Solutions of W(CO)6, Mo(CO)6, and NCS- contained in cavities show strong coupling between the solute chromophores in the mid-infrared and cavity modes. We show that the methodology established with polymer-filled cavities is generally applicable to liquids but that the fluidity of the sample complicates the cavity construction. Varied cavity thicknesses can give rise to spatial gradients in coupling strength and difficulty in targeting a specific cavity-mode order. We also compare the transmission of the mixed vibrational-cavity modes in cavities constructed from either metallic or dielectric reflectors which impacts the cavity resonance line width. NRC Postdoctoral Fellow.

  12. Silicon resonant cavity enhanced photodetector arrays for optical interconnects

    NASA Astrophysics Data System (ADS)

    Emsley, Matthew Kent

    High bandwidth short distance communications standards are being developed based on parallel optical interconnect fiber arrays to meet the needs of increasing data rates of inter-chip communication in modern computer architecture. To ensure that this standard becomes an attractive option for computer systems, low cost components must be implemented on both the transmitting and receiving end of the fibers. To meet this low cost requirement silicon based receiver circuits are the most viable option, however, manufacturing high speed, high efficiency silicon photodetectors presents a technical challenge. Resonant cavity enhanced photodetectors have been shown to provide the required bandwidth-efficiency product but have remained a challenge to reproduce through commercially available fabrication techniques. In this work, commercially reproducible silicon wafers with a high reflectance buried distributed Bragg reflector (DBR) have been designed and fabricated. The substrates consist of a two-period, 90% reflecting, DBR fabricated using a double silicon-on-insulator (SOI) process. Resonant-cavity-enhanced (RCE) Si photodetectors have been fabricated with 40% quantum efficiency at 860 nm, a FWHM of 25 ps, and a 3dB bandwidth in excess of 10 GHz. Si RCE 12 x 1 photodetector arrays have been fabricated and packaged with silicon based amplifiers to demonstrate the feasibility of a low cost monolithic silicon photoreceiver array.

  13. Long distance measurement using optical sampling by cavity tuning.

    PubMed

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Balling, Petr; Li, Jianshuang; Qu, Xinghua

    2016-05-15

    We experimentally demonstrate a method enabling absolute distance measurement based on optical sampling by cavity tuning. The cross-correlation patterns can be obtained by sweeping the repetition frequency of the frequency comb. The 114 m long fiber delay line, working as the reference arm, is actively stabilized by using a feedback servo loop with 10-10 level stability. The unknown distance can be measured via the instantaneous repetition frequency corresponding to the peak of the fringe packet. We compare the present technique with the reference incremental interferometer, and the experimental results show an agreement within 3 μm over 60 m distance, corresponding to 10-8 level in relative.

  14. Logically combined photonic crystal - A Fabry Perot optical cavity

    NASA Astrophysics Data System (ADS)

    Alagappan, G.; Png, C. E.

    2016-11-01

    We address the logical combination, as opposed to the linear superposition, of two one - dimensional photonic crystals of slightly different periodicities. The original short range translational symmetry is destroyed in these quasi - periodic system. This induces a strong coupling between Bloch modes of different translational wavevectors, and results in a large number of slow modes in such logically combined photonic crystal. In this article, we show by exploiting the beating feature characteristics of the topology of our system, that these slow modes can be effectively described as modes of a Fabry Perot optical cavity made of a homogenous metamaterial with a dispersive refractive index. The homogenized refractive index of the equivalent metamaterial can be obtained from the band structure calculations, using an extended zone scheme. The density of the slow modes in the logically combined photonic crystal is inversely proportional to the group index of the equivalent metamaterial.

  15. Measurements of optical loss in transparent solids using a novel spectrometer based on optical cavity decay

    SciTech Connect

    Milanovich, F.P.; Hunt, J.T.; Roe, J.N.

    1988-12-14

    Recent advances in High Average Power (HAP) solid state lasers and the development of new concept lasers with the potential of ultra- high average power output have put increasing demands on the transparency of optical window materials. To gain a better understanding of the current status of window materials and to direct research toward more nearly transparent materials, we have constructed an optical characterization facility with the purpose of making quantitative optical loss measurements in the sensitivity range of 10/sup /minus/3/ to 10/sup /minus/6/ cm/sup /minus/1/. The cornerstone of this facility is a scanning optical lossmeter in which loss is determined by comparing the decay time of an optical cavity with and without a transparent solid present. The lossmeter has been successfully applied to measurements of the optical loss of witness samples of highly transparent fused silica. A description of the lossmeter and a compilation of preliminary loss measurements are presented here. 3 refs.

  16. A 100 Mbps resonant cavity phase modulator for coherent optical communications

    NASA Technical Reports Server (NTRS)

    Chen, Chien-Chung; Robinson, Deborah L.; Hemmati, Hamid

    1992-01-01

    A resonant cavity electro-optic phase modulator has been designed and implemented to operate at a data rate of 100 Mbps. The modulator consists of an electro-optic crystal located in a highly resonant cavity. The cavity is electro-optically tuned on and off resonance, and the phase dispersion near the cavity resonance provides the output phase modulation. The performance of the modulator was measured by first heterodyne detecting the signal to an intermediate frequency and then measuring the spectral characteristics using an RF spectrum analyzer. The measured phase shift is shown to be in good agreement with the theoretical predictions.

  17. Suppressing spectral diffusion of emitted photons with optical pulses

    DOE PAGES

    Fotso, H. F.; Feiguin, A. E.; Awschalom, D. D.; ...

    2016-01-22

    In many quantum architectures the solid-state qubits, such as quantum dots or color centers, are interfaced via emitted photons. However, the frequency of photons emitted by solid-state systems exhibits slow uncontrollable fluctuations over time (spectral diffusion), creating a serious problem for implementation of the photon-mediated protocols. Here we show that a sequence of optical pulses applied to the solid-state emitter can stabilize the emission line at the desired frequency. We demonstrate efficiency, robustness, and feasibility of the method analytically and numerically. Taking nitrogen-vacancy center in diamond as an example, we show that only several pulses, with the width of 1more » ns, separated by few ns (which is not difficult to achieve) can suppress spectral diffusion. As a result, our method provides a simple and robust way to greatly improve the efficiency of photon-mediated entanglement and/or coupling to photonic cavities for solid-state qubits.« less

  18. Optical-Fiber Thermal-Wave-Cavity Technique to Study Thermal Properties of Silver/Clay Nanofliuds

    NASA Astrophysics Data System (ADS)

    Noroozi, M.; Radiman, S.; Zakaria, A.; Shameli, K.; Deraman, M.; Soltaninejad, S.; Abedini, A.

    2014-10-01

    Thermal properties enhancement of nanofluids have varied strongly with synthesis technique, particle size and type, concentration and agglomeration with time. This study explores the possibility of changing the thermal wave signal of Ag/clay nanofluids into a thermal diffusivity measurement at well dispersion or aggregation of nanoparticles in the base fluid. Optical-Fiber Thermal-Wave-Cavity (OF-TWC) technique was achieved by using a small amount of nanofluid (only 0.2 mL) between fiber optic tip and the Pyroelectric detector and the cavity-length scan was performed. We established the accuracy and precision of this technique by comparing the thermal diffusivity of distilled water to values reported in the literature. Assuming a linear Pyroelectric signal response, the results show that adding clay reduced the thermal diffusivity of water, while increasing the Ag concentration from 1 to 5 wt.% increased the thermal diffusivity of the Ag nanofluid from 1.524×10-3 to 1.789×10-3 cm2/s. However, in particular, nanoparticles show the tendency to form aggregates over time that correlated with the performance change of thermal properties of nanofluid. Our results confirm the high sensitivity of OF-TWC technique raises the potential to be applied to measuring the optical and thermal properties of nanofluids. Furthermore, this technique allows the extraction of information not obtained using other traditional techniques.

  19. Information theoretic regularization in diffuse optical tomography.

    PubMed

    Panagiotou, Christos; Somayajula, Sangeetha; Gibson, Adam P; Schweiger, Martin; Leahy, Richard M; Arridge, Simon R

    2009-05-01

    Diffuse optical tomography (DOT) retrieves the spatially distributed optical characteristics of a medium from external measurements. Recovering the parameters of interest involves solving a nonlinear and highly ill-posed inverse problem. This paper examines the possibility of regularizing DOT via the introduction of a priori information from alternative high-resolution anatomical modalities, using the information theory concepts of mutual information (MI) and joint entropy (JE). Such functionals evaluate the similarity between the reconstructed optical image and the prior image while bypassing the multimodality barrier manifested as the incommensurate relation between the gray value representations of corresponding anatomical features in the two modalities. By introducing structural information, we aim to improve the spatial resolution and quantitative accuracy of the solution. We provide a thorough explanation of the theory from an imaging perspective, accompanied by preliminary results using numerical simulations. In addition we compare the performance of MI and JE. Finally, we have adopted a method for fast marginal entropy evaluation and optimization by modifying the objective function and extending it to the JE case. We demonstrate its use on an image reconstruction framework and show significant computational savings.

  20. A simplified model for thermal-wave cavity self-consistent measurement of thermal diffusivity

    SciTech Connect

    Shen, Jun Zhou, Jianqin; Gu, Caikang; Neill, Stuart; Michaelian, Kirk H.; Fairbridge, Craig; Astrath, Nelson G. C.; Baesso, Mauro L.

    2013-12-15

    A simplified theoretical model was developed for the thermal-wave cavity (TWC) technique in this study. This model takes thermal radiation into account and can be employed for absolute measurements of the thermal diffusivity of gas and liquid samples without any knowledge of geometrical and thermal parameters of the components of the TWC. Using this model and cavity-length scans, thermal diffusivities of air and distilled water were accurately and precisely measured as (2.191 ± 0.004) × 10{sup −5} and (1.427 ± 0.009) × 10{sup −7} m{sup 2} s{sup −1}, respectively, in very good agreement with accepted literature values.

  1. Double-diffusive natural convection in a fluid saturated porous cavity with a freely convecting wall

    SciTech Connect

    Nithiarasu, P.; Sundararajan, T.; Seetharamu, K.N.

    1997-12-01

    Double-diffusive natural convection in fluid saturated porous medium has been investigated using a generalized porous medium model. One of the vertical walls of the porous cavity considered is subjected to convective heat and mass transfer conditions. The results show that the flow, heat and mass transfer become sensitive to applied mass transfer coefficient in both the Darcy and non-Darcy flow regimes. It is also observed that the Sherwood number approaches a constant value as the solutal Biot number increases. Double-diffusive natural convection in fluid saturated porous medium is encountered in applications such as food processing, contaminant transport in ground water, and others.

  2. Diffusion and rheology in a suspension of hydrodynamically interacting colloids enclosed by a spherical cavity

    NASA Astrophysics Data System (ADS)

    Aponte-Rivera, Christian; Zia, Roseanna

    2014-11-01

    We study diffusion and rheology of a suspension of hydrodynamically interacting colloidal spheres enclosed by a spherical cavity, utilizing the Stokesian Dynamics framework to account for long-range many-body and pairwise lubrication interactions between the particles and between particle and enclosure. Previous studies of 1D- and 2D-confined suspensions have revealed that boundaries exert a pronounced qualitative influence on microstructure, dynamics, and rheology. While studies of the motion of a point particle in a cavity have been reported, the neglect of finite size sacrifices significant qualitative information, resulting in an incorrect coupling between torque and velocity, among others. We have derived new hydrodynamic mobility functions for finite-size particles confined by a spherical boundary that faithfully capture the physics of the boundary and its influence on particle dynamics. We obtain the full grand-mobility matrix and, from these, the position-dependent short-time self-diffusivity for an isolated particle and the dynamics of a hydrodynamically interacting pair suspended in the cavity. Both of these are studied over a range of particle-to-cavity size ratios. This material is based upon work supported by the NSF GRFP under Grant No. DGE-0707428. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.

  3. Open Quantum System Studies of Optical Lattices and Nonlinear Optical Cavities: A Comprehensive Development of Atomtronics

    NASA Astrophysics Data System (ADS)

    Pepino, Ronald A.

    2011-12-01

    A generalized open quantum theory that models the transport properties of bosonic systems is derived from first principles. This theory is shown to correctly describe the long-time behavior of a specific class of non-Markovian system-reservoir interactions. Starting with strongly-interacting bosons in optical lattices, we use this theory to construct a novel, one-to-one analogy with electronic systems, components, and devices. Beginning with the concept of a wire, we demonstrate theoretically the ultracold boson analog of a semiconductor diode, a field-effect transistor, and a bipolar junction transistor. In a manner directly analogous to electronics, we show that it is possible to construct combinatorial logic structures from the fundamental electronic-emulating devices just described. In this sense, our proposal for atomtronic devices is a useful starting point for arrangements with more complex functionality. In addition we show that the behavior of the proposed diode should also be possible utilizing a weakly-interacting, coherent bosonic drive. After demonstrating the formal equivalence between systems comprised of bosons in optical lattices and photons in nonlinear cavity networks, we use the formalism to extend the ideas and concepts developed earlier in ultracold boson systems to nonlinear optical systems. We adapt the open quantum system theory to this new physical environment, and demonstrate theoretically how a few-photon optical diode can be realized in a coupled nonlinear cavity system. An analysis of different practical cavity quantum electrodynamics systems is presented and experimentally-viable candidates are evaluated.

  4. Hyperspectral image reconstruction for diffuse optical tomography

    PubMed Central

    Larusson, Fridrik; Fantini, Sergio; Miller, Eric L.

    2011-01-01

    We explore the development and performance of algorithms for hyperspectral diffuse optical tomography (DOT) for which data from hundreds of wavelengths are collected and used to determine the concentration distribution of chromophores in the medium under investigation. An efficient method is detailed for forming the images using iterative algorithms applied to a linearized Born approximation model assuming the scattering coefficient is spatially constant and known. The L-surface framework is employed to select optimal regularization parameters for the inverse problem. We report image reconstructions using 126 wavelengths with estimation error in simulations as low as 0.05 and mean square error of experimental data of 0.18 and 0.29 for ink and dye concentrations, respectively, an improvement over reconstructions using fewer specifically chosen wavelengths. PMID:21483616

  5. Direct Measurement of Large, Diffuse, Optical Structures

    NASA Technical Reports Server (NTRS)

    Saif, Babak N.; Keski-Kuha, Ritva; Feinberg, Lee; Wyant, J. C.; Atkinson, C.

    2004-01-01

    Digital Speckle Pattern Interferometry (DSPI) is a well-established method for the measurement of diffuse objects in experimental mechanics. DSPIs are phase shifting interferometers. Three or four bucket temporal phase shifting algorithms are commonly used to provide phase shifting. These algorithms are sensitive to vibrations and can not be used to measure large optical structures far away from the interferometer. In this research a simultaneous phase shifted interferometer, PhaseCam product of 4D Technology Corporation in Tucson Arizona, is modified to be a Simultaneous phase shifted Digital Speckle Pattern Interferometer (SDSPI). Repeatability, dynamic range, and accuracy of the SDSPI are characterized by measuring a 5 cm x 5 cm carbon fiber coupon.

  6. Cascadable all-optical inverter based on a nonlinear vertical-cavity semiconductor optical amplifier.

    PubMed

    Zhang, Haijiang; Wen, Pengyue; Esener, Sadik

    2007-07-01

    We report, for the first time to our knowledge, the operation of a cascadable, low-optical-switching-power(~10 microW) small-area (~100 microm(2)) high-speed (80 ps fall time) all-optical inverter. This inverter employs cross-gain modulation, polarization gain anisotropy, and highly nonlinear gain characteristics of an electrically pumped vertical-cavity semiconductor optical amplifier (VCSOA). The measured transfer characteristics of such an optical inverter resemble those of standard electronic metal-oxide semiconductor field-effect transistor-based inverters exhibiting high noise margin and high extinction ratio (~9.3 dB), making VCSOAs an ideal building block for all-optical logic and memory.

  7. All-optical flip-flop based on vertical cavity semiconductor optical amplifiers.

    PubMed

    Song, Deqiang; Gauss, Veronica; Zhang, Haijiang; Gross, Matthias; Wen, Pengyue; Esener, Sadik

    2007-10-15

    We report the operation of an all-optical set-reset (SR) flip-flop based on vertical cavity semiconductor optical amplifiers (VCSOAs). This flip-flop is cascadable, has low optical switching power (~10 microW), and has the potential to be integrated on a small footprint (~100 microm(2)). The flip-flop is composed of two cross-coupled electrically pumped VCSOA inverters and uses the principles of cross-gain modulation, polarization gain anisotropy, and highly nonlinear gain characteristics to achieve flip-flop functionality. We believe that, when integrated on chip, this type of all-optical flip-flop opens new prospects for implementing all-optical fast memories and timing regeneration circuits.

  8. Lasing optical cavities based on macroscopic scattering elements.

    PubMed

    Consoli, Antonio; López, Cefe

    2017-01-10

    Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials.

  9. Lasing optical cavities based on macroscopic scattering elements

    PubMed Central

    Consoli, Antonio; López, Cefe

    2017-01-01

    Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials. PMID:28071675

  10. Silicon resonant-cavity-enhanced photodetector arrays for optical interconnects

    NASA Astrophysics Data System (ADS)

    Emsley, Matthew K.; Dosunmu, Olufemi I.; Muller, Paul; Unlu, M. Selim; Leblebici, Yusuf

    2003-08-01

    High bandwidth short distance communications standards are being developed based on parallel optical interconnect fiber arrays to meet the needs of increasing data rates of inter-chip communication in modern computer architecture. To ensure that this standard becomes an attractive option for computer systems, low cost components must be implemented on both the transmitting and receiving end of the fibers. To meet this low cost requirement silicon based receiver circuits are the most viable option, however, manufacturing high speed, high efficiency silicon photodetectors presents a technical challenge. Resonant cavity enhanced (RCE) Si photodetectors have been shown to provide the required bandwidth-efficiency product and we have recently developed a method to reproduce them through commercially available fabrication techniques. In this work, commercially reproducible silicon wafers with a 90% reflectance buried distributed Bragg reflector (DBR) are used to create Si-RCE photodetector arrays for optical interconnects. The Si-RCE photodetectors have 40% quantum efficiency at 860 nm, a FWHM of 25 ps, and a 3dB bandwidth in excess of 10 GHz. We also demonstrate Si-RCE 12×1 photodetector arrays that have been fabricated and packaged with silicon based amplifiers to demonstrate the feasibility of a low cost monolithic silicon photoreceiver array.

  11. Lasing optical cavities based on macroscopic scattering elements

    NASA Astrophysics Data System (ADS)

    Consoli, Antonio; López, Cefe

    2017-01-01

    Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials.

  12. Innovative spectroscopy of liquids: a fiber optic supercontinuum source and an integrating cavity for scattering-free absorption measurements

    NASA Astrophysics Data System (ADS)

    Mignani, A. G.; Ottevaere, H.; Ciaccheri, L.; Thienpont, H.; Cacciari, I.; Parriaux, O.; Johnson, M.

    2009-10-01

    An innovative fiber optic setup for the scattering-free absorption spectroscopy of liquids is presented. It makes use of an integrating sphere that contains the sample under test, coupled to a fiber optic supercontinuum source and to a fiber optic spectrometer. The highly-bright broadband light shining on the sphere's surface is diffusely reflected and collected by the fiber-coupled spectrometric detector. When an absorbing medium is placed in the cavity, a reduction occurs in the radiance of the sphere. The reduction is related to the absorption and volume of the medium, and is independent of nonabsorbing objects, such as scattering particles, within it. A collection of turbid lubricant oils was considered as a test case for verifying and validating the innovative scheme of diffuse-light absorption spectroscopy. Scattering-free spectra were successfully measured and processed as product fingerprints for the prediction of turbine types and other parameters that indicate oil quality.

  13. Improving diffuse optical tomography with structural a priori from fluorescence diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Ma, Wenjuan; Gao, Feng; Duan, Linjing; Zhu, Qingzhen; Wang, Xin; Zhang, Wei; Wu, Linhui; Yi, Xi; Zhao, Huijuan

    2012-03-01

    We obtain absorption and scattering reconstructed images by incorporating a priori information of target location obtained from fluorescence diffuse optical tomography (FDOT) into the diffuse optical tomography (DOT). The main disadvantage of DOT lies in the low spatial resolution resulting from highly scattering nature of tissue in the near-infrared (NIR), but one can use it to monitor hemoglobin concentration and oxygen saturation simultaneously, as well as several other cheomphores such as water, lipids, and cytochrome-c-oxidase. Up to date, extensive effort has been made to integrate DOT with other imaging modalities such as MRI, CT, to obtain accurate optical property maps of the tissue. However, the experimental apparatus is intricate. In this study, DOT image reconstruction algorithm that incorporates a prior structural information provided by FDOT is investigated in an attempt to optimize recovery of a simulated optical property distribution. By use of a specifically designed multi-channel time-correlated single photon counting system, the proposed scheme in a transmission mode is experimentally validated to achieve simultaneous reconstruction of the fluorescent yield, lifetime, absorption and scattering coefficient. The experimental results demonstrate that the quantitative recovery of the tumor optical properties has doubled and the spatial resolution improves as well by applying the new improved method.

  14. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew Charles Rule

    1999-11-16

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  15. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    DOEpatents

    Pipino, Andrew C. R.; Hudgens, Jeffrey W.

    1999-08-24

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  16. Near-Infrared Diffuse Optical Tomography

    PubMed Central

    Hielscher, A. H.; Bluestone, A. Y.; Abdoulaev, G. S.; Klose, A. D.; Lasker, J.; Stewart, M.; Netz, U.; Beuthan, J.

    2002-01-01

    Diffuse optical tomography (DOT) is emerging as a viable new biomedical imaging modality. Using near-infrared (NIR) light, this technique probes absorption as well as scattering properties of biological tissues. First commercial instruments are now available that allow users to obtain cross-sectional and volumetric views of various body parts. Currently, the main applications are brain, breast, limb, joint, and fluorescence/bioluminescence imaging. Although the spatial resolution is limited when compared with other imaging modalities, such as magnetic resonance imaging (MRI) or X-ray computerized tomography (CT), DOT provides access to a variety of physiological parameters that otherwise are not accessible, including sub-second imaging of hemodynamics and other fast-changing processes. Furthermore, DOT can be realized in compact, portable instrumentation that allows for bedside monitoring at relatively low cost. In this paper, we present an overview of current state-of-the -art technology, including hardware and image-reconstruction algorithms, and focus on applications in brain and joint imaging. In addition, we present recent results of work on optical tomographic imaging in small animals. PMID:14646043

  17. Optical extinction monitor using cw cavity enhanced detection.

    PubMed

    Kebabian, Paul L; Robinson, Wade A; Freedman, Andrew

    2007-06-01

    We present details of an apparatus capable of measuring optical extinction (i.e., scattering and/or absorption) with high precision and sensitivity. The apparatus employs one variant of cavity enhanced detection, specifically cavity attenuated phase shift spectroscopy, using a near-confocal arrangement of two high reflectivity (R approximately 0.9999) mirrors in tandem with an enclosed cell 26 cm in length, a light emitting diode (LED), and a vacuum photodiode detector. The square wave modulated light from the LED passes through the absorption cell and is detected as a distorted wave form which is characterized by a phase shift with respect to the initial modulation. The amount of that phase shift is a function of fixed instrument properties-cell length, mirror reflectivity, and modulation frequency-and of the presence of a scatterer or absorber (air, particles, trace gases, etc.) within the cell. The specific implementation reported here employs a blue LED; the wavelength and spectral bandpass of the measurement are defined by the use of an interference filter centered at 440 nm with a 20 nm wide bandpass. The monitor is enclosed within a standard 19 in. rack-mounted instrumentation box, weighs 10 kg, and uses 70 W of electrical power including a vacuum pump. Measurements of the phase shift induced by Rayleigh scattering from several gases (which range in extinction coefficient from 0.4-32 Mm(-1)) exhibit a highly linear dependence (r(2)=0.999 97) when plotted as the co-tangent of the phase shift versus the expected extinction. Using heterodyne demodulation techniques, we demonstrate a detection limit of 0.04 Mm(-1) (4 x 10(-10) cm(-1)) (2sigma) in 10 s integration time and a base line drift of less than +/-0.1 Mm(-1) over a 24 h period. Detection limits decrease as the square root of integration time out to approximately 150 s.

  18. Energy Pooling Upconversion in Free Space and Optical Cavities

    NASA Astrophysics Data System (ADS)

    LaCount, Michael D.

    energy pooling rate efficiency of 99%. This demonstrates that the energy pooling rate can be made faster than its competing processes. Based on the results of this study, a set of design rules was developed to optimize the rate efficiency of energy pooling. Prior to this research, no attempt had been made to determine if energy pooling could be made to out-pace competing processes--i.e. whether or not a molecular system could be designed to utilize energy pooling as an efficient means of upconversion. This initial investigation was part of a larger effort involving a team of researchers at the University of Colorado, Boulder and at the National Renewable Energy Laboratory. After establishing our computational proof-of-concept, we collectively used the new design rules to select an improved system for energy pooling. This consisted of rhodamine 6G and stilbene-420. These molecules were fabricated into a thin film, and the maximum internal quantum yield was measured to be 36% under sufficiently high intensity light. To further increase the efficiency of energy pooling, encapsulation within optical cavities was considered as a way of changing the rate of processes characterized by electric dipole-dipole coupling. This was carried out using a combination of classical electromagnetism, quantum electrodynamics, and perturbation theory. It was found that, in the near field, if the distance of the energy transfer is smaller than the distance from the energy transfer site and the cavity wall, then the electric dipole-dipole coupling tensor is not influenced by the cavity environment and the rates of energy transfer processes are the same as those in free space. Any increase in energy transfer efficiencies that are experimentally measured must therefore be caused by changing the rate of light absorption and emission. This is an important finding because earlier, less rigorous studies had concluded otherwise. It has been previously demonstrated that an optical cavity can be used to

  19. Duality relation between nonspherical mirror optical cavities and its application to gravitational-wave detectors.

    PubMed

    Agresti, Juri; Chen, Yanbei; D'Ambrosio, Erika; Savov, Pavlin

    2012-09-01

    In this paper, we analytically prove a unique duality relation between the eigenspectra of paraxial optical cavities with nonspherical mirrors: a one-to-one mapping between eigenmodes and eigenvalues of cavities deviating from flat mirrors by h(r) and cavities deviating from concentric mirrors by -h(r), where h need not be a small perturbation. We then illustrate its application to optical cavities, proposed for advanced interferometric gravitational-wave detectors, where the mirrors are designed to support beams with rather flat intensity profiles over the mirror surfaces. This unique mapping might be very useful in future studies of alternative optical designs for advanced gravitational wave interferometers or experiments employing optical cavities with nonstandard mirrors.

  20. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, Bhushan L.

    1995-01-01

    An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

  1. Proposal of using slot-waveguide cavity to reduce noises in resonant integrated optical gyroscopes

    NASA Astrophysics Data System (ADS)

    Jiang, Yi; Kong, Mei; Xu, Yameng

    2016-10-01

    Resonant optical gyroscopes suffer serious performance degradation induced by noises. We propose using an air-gap silicon-on-silica slot waveguide ring resonator as the resonant cavity of a resonant integrated optical gyroscope. We estimate possible backscattering, Kerr effect, polarization fluctuation, and thermal drift in the air-gap slot waveguide. It is shown that the backscattering, Kerr nonlinearity, and thermal instabilities can decrease significantly compared to those in a common solid-core silicon waveguide cavity, and perturbations of the polarization fluctuation may be eliminated. In addition, a slot-waveguide cavity is more beneficial for integration than a photonic bandgap fiber cavity.

  2. Deterministic Loading of Individual Atoms to a High-Finesse Optical Cavity

    SciTech Connect

    Fortier, Kevin M.; Kim, Soo Y.; Gibbons, Michael J.; Ahmadi, Peyman; Chapman, Michael S.

    2007-06-08

    Individual laser-cooled atoms are delivered on demand from a single atom magneto-optic trap to a high-finesse optical cavity using an atom conveyor. Strong coupling of the atom with the cavity field allows simultaneous cooling and detection of individual atoms for time scales exceeding 15 s. The single atom scatter rate is studied as a function of probe-cavity detuning and probe Rabi frequency, and the experimental results are in qualitative agreement with theoretical predictions. We demonstrate the ability to manipulate the position of a single atom relative to the cavity mode with excellent control and reproducibility.

  3. Optical cavity-assisted broadband optical transparency of a plasmonic metal film

    NASA Astrophysics Data System (ADS)

    Liu, Zhengqi; Nie, Yiyou; Yuan, Wen; Liu, Xiaoshan; Huang, Shan; Chen, Jing; Gao, Huogui; Gu, Gang; Liu, Guiqiang

    2015-05-01

    We theoretically present a powerful method to achieve a continuous metal film structure with broadband optical transparency via introducing a dielectric Fabry-Pérot (FP) cavity. An incident optical field could be efficiently coupled and confined with the strong localized plasmons by the non-close-packed plasmonic crystal at the input part and could then become re-radiated output via the transmission channel supported by the dielectric cavity. The formed photonic-plasmonic system could therefore make the seamless metal film structure have a superior near-unity transparency (up to 97%) response and a broadband transparent spectrum with bandwidth >245 nm (with transmittance >90%) in the optical regime. The observed optical properties of the proposed structure can be highly tuned via varying the structural parameters. Based on the colloidal assembly method, the proposed plasmonic crystal can be fabricated in a large area. In addition, the achieved optical transparency can be retained in the extremely roughed metal film structure. Thereby, the findings could offer a feasible way to achieve a broadband transparent metal film structure and hold potential applications in transparent electrodes, touch screens and interactive electronics.

  4. Optical cavity-assisted broadband optical transparency of a plasmonic metal film.

    PubMed

    Liu, Zhengqi; Nie, Yiyou; Yuan, Wen; Liu, Xiaoshan; Huang, Shan; Chen, Jing; Gao, Huogui; Gu, Gang; Liu, Guiqiang

    2015-05-08

    We theoretically present a powerful method to achieve a continuous metal film structure with broadband optical transparency via introducing a dielectric Fabry-Pérot (FP) cavity. An incident optical field could be efficiently coupled and confined with the strong localized plasmons by the non-close-packed plasmonic crystal at the input part and could then become re-radiated output via the transmission channel supported by the dielectric cavity. The formed photonic-plasmonic system could therefore make the seamless metal film structure have a superior near-unity transparency (up to 97%) response and a broadband transparent spectrum with bandwidth >245 nm (with transmittance >90%) in the optical regime. The observed optical properties of the proposed structure can be highly tuned via varying the structural parameters. Based on the colloidal assembly method, the proposed plasmonic crystal can be fabricated in a large area. In addition, the achieved optical transparency can be retained in the extremely roughed metal film structure. Thereby, the findings could offer a feasible way to achieve a broadband transparent metal film structure and hold potential applications in transparent electrodes, touch screens and interactive electronics.

  5. Optical detection of disordered water within a protein cavity.

    PubMed

    Goldbeck, Robert A; Pillsbury, Marlisa L; Jensen, Russell A; Mendoza, Juan L; Nguyen, Rosa L; Olson, John S; Soman, Jayashree; Kliger, David S; Esquerra, Raymond M

    2009-09-02

    Internal water molecules are important to protein structure and function, but positional disorder and low occupancies can obscure their detection by X-ray crystallography. Here, we show that water can be detected within the distal cavities of myoglobin mutants by subtle changes in the absorbance spectrum of pentacoordinate heme, even when the presence of solvent is not readily observed in the corresponding crystal structures. A well-defined, noncoordinated water molecule hydrogen bonded to the distal histidine (His64) is seen within the distal heme pocket in the crystal structure of wild type (wt) deoxymyoglobin. Displacement of this water decreases the rate of ligand entry into wt Mb, and we have shown previously that the entry of this water is readily detected optically after laser photolysis of MbCO complexes. However, for L29F and V68L Mb no discrete positions for solvent molecules are seen in the electron density maps of the crystal structures even though His64 is still present and slow rates of ligand binding indicative of internal water are observed. In contrast, time-resolved perturbations of the visible absorption bands of L29F and V68L deoxyMb generated after laser photolysis detect the entry and significant occupancy of water within the distal pockets of these variants. Thus, the spectral perturbation of pentacoordinate heme offers a potentially robust system for measuring nonspecific hydration of the active sites of heme proteins.

  6. On The Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes

    SciTech Connect

    N.N. Gorelenkov, N.J. Fisch and E. Fredrickson

    2010-03-09

    An enormous wave-particle diffusion coefficient along paths suitable for alpha channeling had been deduced in mode converted ion Bernstein wave experiments on Tokamak Fusion Test Reactor (TFTR) the only plausible explanation advanced for such a large diffusion coefficient was the excitation of internal cavity modes which induce particle diffusion along identical diffusion paths, but at much higher rates. Although such a mode was conjectured, it was never observed. However, recent detailed observations of high frequency compressional Alfven eigenmodes (CAEs) on the National Spherical torus Experiment (NSTX) indirectly support the existence of the related conjectured modes on TFTR. The eigenmodes responsible for the high frequency magnetic activity can be identified as CAEs through the polarization of the observed magnetic field oscillations in NSTX and through a comparison with the theoretically derived freuency dispersion relation. Here, we show how these recent observations of high frequency CAEs lend support to this explanation of the long-standing puzzle of anomalous fast ion energy diffusion on TFTR. The support of the conjecure that these internal modes could have caused the remarkable ion energy diffusion on TFTR carries significant and favorable implications for the possibilities in achieving the alpha channeling effect with small injected power in a tokamak reactor.

  7. A hemispherical, high-solid-angle optical micro-cavity for cavity-QED studies

    NASA Astrophysics Data System (ADS)

    Cui, Guoqiang; Hannigan, J. M.; Loeckenhoff, R.; Matinaga, F. M.; Raymer, M. G.; Bhongale, S.; Holland, M.; Mosor, S.; Chatterjee, S.; Gibbs, H. M.; Khitrova, G.

    2006-03-01

    We report a novel hemispherical micro-cavity that is comprised of a planar integrated semiconductor distributed Bragg reflector (DBR) mirror, and an external, concave micro-mirror having a radius of curvature 50 µm. The integrated DBR mirror containing quantum dots (QD), is designed to locate the QDs at an antinode of the field in order to maximize the interaction between the QD and cavity. The concave micro-mirror, with high-reflectivity over a large solid-angle, creates a diffraction-limited (sub-micron) mode-waist at the planar mirror, leading to a large coupling constant between the cavity mode and QD. The half-monolithic design gives more spatial and spectral tuning abilities, relatively to fully monolithic structures. This unique micro-cavity design will potentially enable us to both reach the cavity quantum electrodynamics (QED) strong coupling regime and realize the deterministic generation of single photons on demand.

  8. A hemispherical, high-solid-angle optical micro-cavity for cavity-QED studies.

    PubMed

    Cui, Guoqiang; Hannigan, J M; Loeckenhoff, R; Matinaga, F M; Raymer, M G; Bhongale, S; Holland, M; Mosor, S; Chatterjee, S; Gibbs, H M; Khitrova, G

    2006-03-20

    We report a novel hemispherical micro-cavity that is comprised of a planar integrated semiconductor distributed Bragg reflector (DBR) mirror, and an external, concave micro-mirror having a radius of curvature 50 microm. The integrated DBR mirror containing quantum dots (QD), is designed to locate the QDs at an antinode of the field in order to maximize the interaction between the QD and cavity. The concave micro-mirror, with high-reflectivity over a large solid-angle, creates a diffraction-limited (sub-micron) mode-waist at the planar mirror, leading to a large coupling constant between the cavity mode and QD. The half-monolithic design gives more spatial and spectral tuning abilities, relatively to fully monolithic structures. This unique micro-cavity design will potentially enable us to both reach the cavity quantum electrodynamics (QED) strong coupling regime and realize the deterministic generation of single photons on demand.

  9. Optical processing furnace with quartz muffle and diffuser plate

    DOEpatents

    Sopori, B.L.

    1996-11-19

    An optical furnace for annealing a process wafer is disclosed comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the wall of the muffle is also provided for controlling the source of optical energy. 5 figs.

  10. Cavity Optical Pulse Extraction: ultra-short pulse generation as seeded Hawking radiation.

    PubMed

    Eilenberger, Falk; Kabakova, Irina V; de Sterke, C Martijn; Eggleton, Benjamin J; Pertsch, Thomas

    2013-01-01

    We show that light trapped in an optical cavity can be extracted from that cavity in an ultrashort burst by means of a trigger pulse. We find a simple analytic description of this process and show that while the extracted pulse inherits its pulse length from that of the trigger pulse, its wavelength can be completely different. Cavity Optical Pulse Extraction is thus well suited for the development of ultrashort laser sources in new wavelength ranges. We discuss similarities between this process and the generation of Hawking radiation at the optical analogue of an event horizon with extremely high Hawking temperature. Our analytic predictions are confirmed by thorough numerical simulations.

  11. A photonic crystal cavity-optical fiber tip nanoparticle sensor for biomedical applications

    NASA Astrophysics Data System (ADS)

    Shambat, Gary; Rajasekhar Kothapalli, Sri; Khurana, Aman; Provine, J.; Sarmiento, Tomas; Cheng, Kai; Cheng, Zhen; Harris, James; Daldrup-Link, Heike; Sam Gambhir, Sanjiv; Vučković, Jelena

    2012-05-01

    We present a sensor capable of detecting solution-based nanoparticles using an optical fiber tip functionalized with a photonic crystal cavity. When sensor tips are retracted from a nanoparticle solution after being submerged, we find that a combination of convective fluid forces and optically induced trapping cause an aggregation of nanoparticles to form directly on cavity surfaces. A simple readout of quantum dot photoluminescence coupled to the optical fiber shows that nanoparticle presence and concentration can be detected through modified cavity properties. Our sensor can detect both gold and iron oxide nanoparticles and can be utilized for molecular sensing applications in biomedicine.

  12. Bose-Einstein condensates in an optical cavity with sub-recoil bandwidth

    NASA Astrophysics Data System (ADS)

    Klinder, J.; Keßler, H.; Georges, Ch.; Vargas, J.; Hemmerich, A.

    2016-12-01

    This article provides a brief synopsis of our recent work on the interaction of Bose-Einstein condensates with the light field inside an optical cavity exhibiting a bandwidth on the order of the recoil frequency. Three different coupling scenarios are discussed giving rise to different physical phenomena at the borderline between the fields of quantum optics and many-body physics. This includes sub-recoil opto-mechanical cooling, cavity-controlled matter wave superradiance and the emergence of a superradiant superfluid or a superradiant Mott insulating many-body phase in a self-organized intra-cavity optical lattice with retarded infinite range interactions.

  13. External cavity diode laser with kilohertz linewidth by a monolithic folded Fabry-Perot cavity optical feedback.

    PubMed

    Zhao, Yang; Peng, Yu; Yang, Tao; Li, Ye; Wang, Qiang; Meng, Fei; Cao, Jianping; Fang, Zhanjun; Li, Tianchu; Zang, Erjun

    2011-01-01

    We present a extended-cavity diode laser (ECDL) with kilohertz linewidth by optical feedback from a monolithic folded Fabry-Perot cavity (MFC). In our experiments, an MFC replaces the retroreflecting mirror in the traditional ECDL configuration. Beat-note measurements between this MFC-ECDL and a narrow-linewidth reference laser are performed and demonstrate that the linewidth of this MFC-ECDL is about 6.8 kHz. Phase locking of this MFC-ECDL to the reference laser is achieved with a unity gain as small as 10.2 kHz.

  14. A tunable fiber-coupled optical cavity for agile enhancement of detector absorption

    NASA Astrophysics Data System (ADS)

    Heath, Robert M.; Tanner, Michael G.; Kirkwood, Robert A.; Miki, Shigehito; Warburton, Richard J.; Hadfield, Robert H.

    2016-09-01

    Maximizing photon absorption into thin active structures can be the limiting factor for photodetector efficiency. In this work, a fiber-coupled tunable cavity is demonstrated, designed to achieve close to unity absorption of photons into a thin film superconducting nanowire single photon detector (SNSPD). A technique for defining a stable cavity between the end of a telecommunications optical fiber and a reflective substrate is described and realized. Cavity resonances are demonstrated both through the tuning of input wavelength and cavity length. The resulting optical cavity can tune the resonant absorption in situ over a wavelength range of 100 nm. This technique is used to maximize the single photon absorption into both a back-side-coupled Au mirror SNSPD and a front-side-coupled distributed Bragg reflector cavity SNSPD. The system detection efficiency (SDE) is limited by imperfections in the thin films, but in both cases we demonstrate an improvement of the SDE by 40% over bare fiber illumination.

  15. Selective engineering of cavity resonance for frequency matching in optical parametric processes

    SciTech Connect

    Lu, Xiyuan; Rogers, Steven; Jiang, Wei C.; Lin, Qiang

    2014-10-13

    We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.

  16. Non-Gaussian statistics and extreme waves in a nonlinear optical cavity.

    PubMed

    Montina, A; Bortolozzo, U; Residori, S; Arecchi, F T

    2009-10-23

    A unidirectional optical oscillator is built by using a liquid crystal light valve that couples a pump beam with the modes of a nearly spherical cavity. For sufficiently high pump intensity, the cavity field presents complex spatiotemporal dynamics, accompanied by the emission of extreme waves and large deviations from the Gaussian statistics. We identify a mechanism of spatial symmetry breaking, due to a hypercycle-type amplification through the nonlocal coupling of the cavity field.

  17. Proposed coupling of an electron spin in a semiconductor quantum dot to a nanosize optical cavity.

    PubMed

    Majumdar, Arka; Kaer, Per; Bajcsy, Michal; Kim, Erik D; Lagoudakis, Konstantinos G; Rundquist, Armand; Vučković, Jelena

    2013-07-12

    We propose a scheme to efficiently couple a single quantum dot electron spin to an optical nano-cavity, which enables us to simultaneously benefit from a cavity as an efficient photonic interface, as well as to perform high fidelity (nearly 100%) spin initialization and manipulation achievable in bulk semiconductors. Moreover, the presence of the cavity speeds up the spin initialization process beyond the GHz range.

  18. Non-local model for diffusion-mediated dislocation climb and cavity growth

    NASA Astrophysics Data System (ADS)

    Rovelli, I.; Dudarev, S. L.; Sutton, A. P.

    2017-06-01

    To design efficient thermal recovery procedures for structural materials in fusion energy applications it is important to characterise quantitatively the annealing timescales of radiation-induced defect clusters. With this goal in mind, we present an extension of the Green's function formulation of Gu et al. (2015). for the climb of curved dislocations, to include in the same framework the evaporation and growth of cavities and the effects of free surfaces. This paper focuses on the mathematical foundations of the model, which makes use of boundary integral equations (París and Cañas, 1997) to solve the steady-state vacancy diffusion problem. Numerical results are also presented in the simplified case of a dilute configuration of prismatic dislocation loops and spherical cavities in a finite-size medium, which show good agreement with experimental data on high temperature annealing in ion-irradiated tungsten (Ferroni et al., 2015).

  19. Performance of resonator fiber optic gyroscope using external-cavity laser stabilization and optical filtering

    NASA Astrophysics Data System (ADS)

    Qiu, Tiequn; Wu, Jianfeng; Strandjord, Lee K.; Sanders, Glen A.

    2014-05-01

    A bench-top resonator fiber optic gyroscope (RFOG) was assembled and tested, showing encouraging progress toward navigation grade performance. The gyro employed a fiber length of 19 meters of polarizing fiber for the sensing coil which was wound on an 11.5 cm diameter PZT cylinder. A bias stability of approximately 0.1 deg/hr was observed over a 2 hour timeframe, which is the best bias stability reported to date in an RFOG to our knowledge. Special care was taken to minimize laser phase noise, including stabilization to an optical cavity which was also used for optical filtering, giving angle random walk (ARW) values in the range of 0.008 deg/rt-hr. The ARW performance and bias stability are within 2x and 10x, respectively, of many civil inertial navigation grade requirements.

  20. Hyperparallel optical quantum computation assisted by atomic ensembles embedded in double-sided optical cavities

    NASA Astrophysics Data System (ADS)

    Li, Tao; Long, Gui-Lu

    2016-08-01

    We propose an effective, scalable, hyperparallel photonic quantum computation scheme in which photonic qubits are hyperencoded both in the spatial degrees of freedom (DOF) and the polarization DOF of each photon. The deterministic hyper-controlled-not (hyper-cnot) gate on a two-photon system is attainable with our interesting interface between the polarized photon and the collective spin wave (magnon) of an atomic ensemble embedded in a double-sided optical cavity, and it doubles the operations in the conventional quantum cnot gate. Moreover, we present a compact hyper-cnotN gate on N +1 hyperencoded photons with only two auxiliary cavity-magnon systems, not more, and it can be faithfully constituted with current experimental techniques. Our proposal enables various applications with the hyperencoded photons in quantum computing and quantum networks.

  1. Excess Noise Depletion of a Bose-Einstein Condensate in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Szirmai, G.; Nagy, D.; Domokos, P.

    2009-02-01

    Quantum fluctuations of a cavity field coupled into the motion of ultracold bosons can be strongly amplified by a mechanism analogous to the Petermann excess noise factor in lasers with unstable cavities. For a Bose-Einstein condensate in a stable optical resonator, the excess noise effect amounts to a significant depletion on long time scales.

  2. Normal Mode Splitting and Mechanical Effects of an Optical Lattice in a Ring Cavity

    NASA Astrophysics Data System (ADS)

    Klinner, Julian; Lindholdt, Malik; Nagorny, Boris; Hemmerich, Andreas

    2006-01-01

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far-detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detuned by about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  3. Normal mode splitting and mechanical effects of an optical lattice in a ring cavity.

    PubMed

    Klinner, Julian; Lindholdt, Malik; Nagorny, Boris; Hemmerich, Andreas

    2006-01-20

    A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far-detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detuned by about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.

  4. All-optical switching in a continuously operated and strongly coupled atom-cavity system

    NASA Astrophysics Data System (ADS)

    Dutta, Sourav; Rangwala, S. A.

    2017-03-01

    We experimentally demonstrate collective strong coupling, optical bi-stability (OB), and all-optical switching in a system consisting of ultracold 85Rb atoms, trapped in a dark magneto-optical trap (DMOT), and coupled to an optical Fabry-Perot cavity. The strong coupling is established by measuring the vacuum Rabi splitting (VRS) of a weak on-axis probe beam. The dependence of VRS on the probe beam power is measured, and bi-stability in the cavity transmission is observed. We demonstrate control over the transmission of the probe beam through the atom-cavity system using a free-space off-axis control beam and show that the cavity transmission can be switched on and off in micro-second timescales using micro-Watt control powers. The utility of the system as a tool for sensitive, in-situ and rapid measurements is envisaged.

  5. History of Diffuse Optical Spectroscopy of Human Tissue

    NASA Astrophysics Data System (ADS)

    Huppert, Theodore J.

    Diffuse optical spectroscopy is a noninvasive method that uses low levels of near-infrared light to measure blood oxygenation in the brain. Over the last 35 years, the number of diffuse optical studies and the range of clinical and research applications have grown steadily. Compared to other neuroimaging methods to measure cerebral blood oxygenation, such as magnetic resonance imaging or positron emission tomography, diffuse optical imaging (DOI) is more cost effective and often uses small portable instrumentation. Wireless and bedside optical systems are currently produced commercially. The portability of these instruments has extended the use of optical methods into several unique applications including brain imaging in infants and children, studies of the brain during ambulatory tasks such as walking or balance, and interoperative brain assessments. This chapter will introduce the history and basic principles of DOI including discussion of the factors contributing to the optical properties of tissue, instrumentation, and an overview of applications of the technology.

  6. Optically tunable chromatic dispersion controller with coupled-cavity etalon structure.

    PubMed

    Shu, Xuewen; Sugden, Kate; Bennion, Ian

    2005-06-15

    We propose and demonstrate a novel optically tunable dynamic dispersion-compensation device with coupled-cavity etalon structure. Experimentally, it was achieved with an all-fiber coupled-cavity etalon made in an Er/Yb codoped fiber pumped by a 980-nm laser diode. The dispersion was tuned from -300 to +400 ps/nm in the experiment. The potential advantages of such optically tunable dispersion compensators include fast response time and remotely controllable operation.

  7. Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers

    DTIC Science & Technology

    1992-12-01

    01 Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers THESIS Presented to the Faculty of the School of Engineering...VCSELs ............................ 3-11 3.4 Injection Lasers : Electrical Pumping .................... 3-12 3.4.1 Active Region Design... lasers on the wafer. x Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers L. Introduction This thesis investigates

  8. Quantum dynamics of an optical cavity coupled to a thin semitransparent membrane: Effect of membrane absorption

    SciTech Connect

    Biancofiore, C.; Karuza, M.; Galassi, M.; Natali, R.; Vitali, D.; Tombesi, P.; Di Giuseppe, G.

    2011-09-15

    We study the quantum dynamics of the cavity optomechanical system formed by a Fabry-Perot cavity with a thin vibrating membrane at its center. We determine in particular to what extent optical absorption by the membrane hinders reaching a quantum regime for the cavity-membrane system. We show that even though membrane absorption may significantly lower the cavity finesse and also heat the membrane, one can still simultaneously achieve ground state cooling of a vibrational mode of the membrane and stationary optomechanical entanglement with state-of-the-art apparatuses.

  9. Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator.

    PubMed

    Shambat, Gary; Ellis, Bryan; Mayer, Marie A; Majumdar, Arka; Haller, Eugene E; Vučković, Jelena

    2011-04-11

    We demonstrate a gallium arsenide photonic crystal cavity injection-based electro-optic modulator coupled to a fiber taper waveguide. The fiber taper serves as a convenient and tunable waveguide for cavity coupling with minimal loss. Localized electrical injection of carriers into the cavity region via a laterally doped p-i-n diode combined with the small mode volume of the cavity enable ultra-low energy modulation at sub-fJ/bit levels. Speeds of up to 1 GHz are demonstrated with photoluminescence lifetime measurements revealing that the ultimate limit goes well into the tens of GHz.

  10. Cooperative effects of two optical dipole antennas coupled to plasmonic Fabry-Pérot cavity.

    PubMed

    Yang, Zhong-Jian; Wang, Qu-Quan; Lin, Hai-Qing

    2012-09-07

    We investigate the cooperative effects of two optical dipole antennas that are coupled to a finite Au nanowire acting as plasmonic Fabry-Pérot (F-P) cavity. The coherent coupling between one single antenna and the F-P cavity can result in Fano resonance, and the coupling strength is antenna position dependent. For two antennas coupled to the F-P cavity, constructive or destructive interference between antennas could be achieved by adjusting their positions along the F-P cavity. Consequently, the Fano resonance will become stronger or weaker correspondingly.

  11. External cavity diode laser based upon an FBG in an integrated optical fiber platform.

    PubMed

    Lynch, Stephen G; Holmes, Christopher; Berry, Sam A; Gates, James C; Jantzen, Alexander; Ferreiro, Teresa I; Smith, Peter G R

    2016-04-18

    An external cavity diode laser is demonstrated using a Bragg grating written into a novel integrated optical fiber platform as the external cavity. The cavity is fabricated using flame-hydrolysis deposition to bond a photosensitive fiber to a silica-on-silicon wafer, and a grating written using direct UV-writing. The laser operates on a single mode at the acetylene P13 line (1532.83 nm) with 9 mW output power. The noise properties of the laser are characterized demonstrating low linewidth operation (< 14 kHz) and superior relative intensity noise characteristics when compared to a commercial tunable external cavity diode laser.

  12. Intra-cavity cryogenic optical refrigeration using high power vertical external-cavity surface-emitting lasers (VECSELs).

    PubMed

    Ghasemkhani, Mohammadreza; Albrecht, Alexander R; Melgaard, Seth D; Seletskiy, Denis V; Cederberg, Jeffrey G; Sheik-Bahae, Mansoor

    2014-06-30

    A 7% Yb:YLF crystal is laser cooled to 131 ± 1 K from room temperature by placing it inside the external cavity of a high power InGaAs/GaAs VECSEL operating at 1020 nm with 0.15 nm linewidth. This is the lowest temperature achieved in the intracavity geometry to date and presents major progress towards realizing an all-solid-state compact optical cryocooler.

  13. Towards a monolithic optical cavity for atom detection and manipulation

    NASA Astrophysics Data System (ADS)

    Gleyzes, S.; El Amili, A.; Cornelussen, R. A.; Lalanne, P.; Westbrook, C. I.; Aspect, A.; Estève, J.; Moreau, G.; Martinez, A.; Lafosse, X.; Ferlazzo, L.; Harmand, J. C.; Mailly, D.; Ramdane, A.

    2009-05-01

    We study a Fabry-Perot cavity formed from a ridge waveguide on a AlGaAs substrate. We experimentally determined the propagation losses in the waveguide at 780 nm, the wavelength of Rb atoms. We have also made a numerical and analytical estimate of the losses induced by the presence of the gap which would allow the interaction of cold atoms with the cavity field. We found that the intrinsic finesse of the gapped cavity can be on the order of F˜30, which, when one takes into account the losses due to mirror transmission, corresponds to a cooperativity parameter for our system C˜1.

  14. Ultrafast Optics: Vector Cavity Laser - Physics and Technology

    DTIC Science & Technology

    2016-06-14

    4142 (1997). 11. D. Y. Tang, J. Guo, Y. F. Song , L. Li, L. M. Zhao, and D. Y. Shen, "GHz pulse train generation in fiber lasers by cavity induced...polarization coupling in a birefringent cavity fiber laser," Opt. Lett. 33, 2317-2319(2008). 21. D. Y. Tang, Y. F. Song , J. Guo, Y. J. Xiang, and D...1051-1053(2005). 28. D. Y. Tang, J. Guo, Y. F. Song , G. D. Shao, L. M. Zhao, and D. Y. Shen, "Temporal cavity soliton formation in an anomalous

  15. Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity

    SciTech Connect

    Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun

    2015-11-24

    We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate.

  16. Power enhancement of burst-mode ultraviolet pulses using a doubly resonant optical cavity.

    PubMed

    Rakhman, Abdurahim; Notcutt, Mark; Liu, Yun

    2015-12-01

    We report a doubly resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed, and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (1064 nm) and its frequency-tripled ultraviolet (355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber-optic frequency shifter. The DREC technique enables novel applications of optical cavities to power enhancement of burst-mode lasers with arbitrary macropulse width and repetition rate.

  17. Tuning the Sensitivity of an Optical Cavity with Slow and Fast Light

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Myneni, Krishna; Chang, H.; Toftul, A.; Schambeau, C.; Odutola, J. A.; Diels, J. C.

    2012-01-01

    We have measured mode pushing by the dispersion of a rubidium vapor in a Fabry-Perot cavity and have shown that the scale factor and sensitivity of a passive cavity can be strongly enhanced by the presence of such an anomalous dispersion medium. The enhancement is the result of the atom-cavity coupling, which provides a positive feedback to the cavity response. The cavity sensitivity can also be controlled and tuned through a pole by a second, optical pumping, beam applied transverse to the cavity. Alternatively, the sensitivity can be controlled by the introduction of a second counter-propagating input beam that interferes with the first beam, coherently increasing the cavity absorptance. We show that the pole in the sensitivity occurs when the sum of the effective group index and an additional cavity delay factor that accounts for mode reshaping goes to zero, and is an example of an exceptional point, commonly associated with coupled non-Hermitian Hamiltonian systems. Additionally we show that a normal dispersion feature can decrease the cavity scale factor and can be generated through velocity selective optical pumping

  18. Measurement-based generation of shaped single photons and coherent state superpositions in optical cavities

    NASA Astrophysics Data System (ADS)

    Lecamwasam, Ruvindha L.; Hush, Michael R.; James, Matthew R.; Carvalho, André R. R.

    2017-01-01

    We propose related schemes to generate arbitrarily shaped single photons, i.e., photons with an arbitrary temporal profile, and coherent state superpositions using simple optical elements. The first system consists of two coupled cavities, a memory cavity and a shutter cavity, containing a second-order optical nonlinearity and electro-optic modulator (EOM), respectively. Photodetection events of the shutter cavity output herald preparation of a single photon in the memory cavity, which may be stored by immediately changing the optical length of the shutter cavity with the EOM after detection. On-demand readout of the photon, with arbitrary shaping, can be achieved through modulation of the EOM. The second scheme consists of a memory cavity with two outputs, which are interfered, phase shifted, and measured. States that closely approximate a coherent state superposition can be produced through postselection for sequences of detection events, with more photon detection events leading to a larger superposition. We furthermore demonstrate that no-knowledge feedback can be easily implemented in this system and used to preserve the superposition state, as well as provide an extra control mechanism for state generation.

  19. Coupled-Cavity Interferometer for the Optics Laboratory

    ERIC Educational Resources Information Center

    Peterson, R. W.

    1975-01-01

    Describes the construction of a flexible coupled-cavity interferometer for student use. A helium-neon laser and phonograph turntable are the main components. Lists activities which may be performed with the apparatus. (Author/CP)

  20. Coupled-Cavity Interferometer for the Optics Laboratory

    ERIC Educational Resources Information Center

    Peterson, R. W.

    1975-01-01

    Describes the construction of a flexible coupled-cavity interferometer for student use. A helium-neon laser and phonograph turntable are the main components. Lists activities which may be performed with the apparatus. (Author/CP)

  1. Clinical measurements of tissue optical properties in the esophagus and in the oral cavity

    NASA Astrophysics Data System (ADS)

    Bays, Roland; Wagnieres, Georges A.; Robert, D.; Mizeret, Jerome C.; Braichotte, Daniel; Savary, Jean-Francois; Monnier, Philippe; van den Bergh, Hubert

    1995-03-01

    A non-invasive probe has been devised and clinically used to perform in vivo measurements of the optical properties of the esophageal wall and oral cavity. The absorption and reduced scattering coefficients are determined from the observation of the spatial distribution of the diffuse reflectance at the tissue surface under a narrow beam illumination of the tissue. The determination of these two coefficients enables us to evaluate the value of the effective attenuation coefficient which is of major interest in the field of light dosimetry for photodynamic therapy (PDT). An invasive isotropic micro-probe has also been designed and clinically used to directly measure in vivo the value of the fluence rate in tissues. The principle of this probe is based on the fluorescence generated in a ruby sphere by the light which propagates in the tissue. This fluorescence which can be excited between 350 and 680 nm is isotropically emitted and in part collected by an optical fiber glued against the ruby sphere. Results, obtained with both probes at 514 and 630 nm, i.e., wavelengths of interest in photodynamic therapy, with actual clinically used photosensitizers are summarized and compared. The agreement obtained between these two techniques validates the principle of these measurements.

  2. Entanglement preparation and quantum communication with atoms in optical cavities

    SciTech Connect

    Xue Peng; Han Chao; Yu Bo; Lin Xiumin; Guo Guangcan

    2004-05-01

    We propose an experimentally feasible scheme to generate general entangled states between atoms in spatially separate cavities, and then show one of the applications--a secure communication allowing asymptotically key distribution and quasisecure direct communication. The scheme involves laser manipulation of atoms in a high-Q cavity, adjustable quarter- and half-wave plates, beam splitter, polarizing beam splitters, and single-photon detectors, and well fits the status of the current experimental technology.

  3. High finesse optical fiber cavities: optimal alignment and robust stabilization (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ratschbacher, Lothar; Gallego, Jose; Ghosh, Sutapa; Alavi, Seyed; Alt, Wolfgang; Martinez-Dorantes, Miguel; Meschede, Dieter

    2016-04-01

    Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications. Some of the most promising areas of application of these optical micro-resonators with high finesse and small mode volume are in the field of quantum communication and information. The resonator-enhanced light-matter interaction, for instance, provide basis for the realization of efficient optical interfaces between stationary matter-based quantum nodes and flying single-photon qubits. To date fiber Fabry-Perot cavities have been successfully applied in experiments interfacing single photons with a wide range of quantum systems, including cold atoms, ions and solid state emitters as well as quantum optomechanical experiments. Here we address some important practical questions that arise during the experimental implementation of high finesse fiber Fabry-Perot cavities: How can optimal fiber cavity alignment be achieved and how can the efficiency of coupling light from the optical fibers to the cavity mode and vice versa be characterized? How should optical fiber cavities be constructed and stabilized to fulfill their potential for miniaturization and integration into robust scientific and technological devices that can operate outside of dedicated laboratory environments in the future? The first two questions we answer with an analytic mode matching calculation that relates the alignment dependent fiber-to-cavity mode-matching efficiency to the easily measurable dip in the reflected light power at the cavity resonance. Our general analysis provides a simple recipe for the optimal alignment of fiber Fabry-Perot cavities and moreover for the first time explains the asymmetry in their reflective line shapes. The latter question we explore by investigating a novel, intrinsically rigid fiber cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal

  4. Dynamic model of hydrogen peroxide diffusion kinetics into the pulp cavity.

    PubMed

    Kwon, So Ran; Li, Yiming; Oyoyo, Udochukwu; Aprecio, Raydolfo M

    2012-07-01

    To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate short-term tooth color changes after bleaching. Twenty extracted human canines were sectioned, pulp tissue removed and the cavity enlarged. Teeth were painted with nail varnish to leave a 6-mm diameter circle on the buccal surface. Baseline color was measured spectrophotometrically. Teeth were randomized into a control group (n = 10) treated with 30 µl of glycerin base and a bleaching group (n = 10) exposed to 30 µl of 40% hydrogen peroxide for 1 hour. A linear low density polyethylene wrap was placed to prevent evaporation of the material. Acetate buffer was placed into the cavity and replenished every 10 minutes and placed into plastic tubes. Hydrogen peroxide amount was estimated spectrophotometrically using leukocrystal violet and horseradish peroxidase. Specimen color was remeasured immediately after bleaching, 1 hour, 1 day 1, 2 and 6 weeks postbleaching. Color change was measured per Commission Internationale de l'Eclairage methodology. Mann-Whitney procedure was used to assess baseline color measurements and total hydrogen peroxide penetration amount. Friedman's test was used to assess within group differences for color change and hydrogen peroxide penetration. There was significantly greater hydrogen peroxide penetration in the bleaching group (p < 0.05). Hydrogen peroxide penetration levels were constant throughout the 1-hour evaluation period in the bleaching group. The groups showed no difference at baseline with respect to any of L*a*b color measurements (p > 0.05). The postbleaching color measurement showed an increase of change in overall color (ΔE) and lightness (ΔL) up to 1 week followed by a gradual stabilization up to 6 weeks. This dynamic model provided information about the time course diffusion kinetics into the pulp cavity, demonstrating constant penetration of hydrogen peroxide into the pulp cavity during a 1-hour bleaching session. A prolonged

  5. A method for cleaning optical precision surface of laser gyro cavity

    NASA Astrophysics Data System (ADS)

    Cui, Ying; Jiao, Ling Yan; Lin, Na Na; Zhang, Dong

    2016-10-01

    Laser gyro is the only one non-electromechanical high-precision inertial sensitive instruments in aircraft inertial guidance systems. Ultra high vacuum acquisition is a key segment during the manufacturing process of laser gyro. The surface cleanliness and integrity have decisive influence on the sealing performance of ultra-high vacuum. A cleaning technology for the optical surface of laser gyro cavity was found by experiment. Meanwhile, the analysis of the adsorption mechanism of contaminant on the laser gyro cavity surface and overview of common optical element cleaning technology were given. The result showed that the new cleaning technology improved the cleanliness of the cavity optical surface without any damage and provided a reliable solution for chronic leak of high precision laser gyro cavity.

  6. Feasibility of a feedback control of atomic self-organization in an optical cavity

    SciTech Connect

    Ivanov, D. A. Ivanova, T. Yu.

    2015-08-15

    Many interesting nonlinear effects are based on the strong interaction of motional degrees of freedom of atoms with an optical cavity field. Among them is the spatial self-organization of atoms in a pattern where the atoms group in either odd or even sites of the cavity-induced optical potential. An experimental observation of this effect can be simplified by using, along with the original cavity-induced feedback, an additional electronic feedback based on the detection of light leaking the cavity and the control of the optical potential for the atoms. Following our previous study, we show that this approach is more efficient from the laser power perspective than the original scheme without the electronic feedback.

  7. Feasibility of a feedback control of atomic self-organization in an optical cavity

    NASA Astrophysics Data System (ADS)

    Ivanov, D. A.; Ivanova, T. Yu.

    2015-08-01

    Many interesting nonlinear effects are based on the strong interaction of motional degrees of freedom of atoms with an optical cavity field. Among them is the spatial self-organization of atoms in a pattern where the atoms group in either odd or even sites of the cavity-induced optical potential. An experimental observation of this effect can be simplified by using, along with the original cavity-induced feedback, an additional electronic feedback based on the detection of light leaking the cavity and the control of the optical potential for the atoms. Following our previous study, we show that this approach is more efficient from the laser power perspective than the original scheme without the electronic feedback.

  8. Cavity modes with optical orbital angular momentum in a metamaterial ring based on transformation optics.

    PubMed

    Wu, H W; Wang, F; Dong, Y Q; Shu, F Z; Zhang, K; Peng, R W; Xiong, X; Wang, Mu

    2015-12-14

    In this work, we theoretically study the cavity modes with transverse orbital angular momentum in metamaterial ring based on transformation optics. The metamaterial ring is designed to transform the straight trajectory of light into the circulating one by enlarging the azimuthal angle, effectively presenting the modes with transverse orbital angular momentum. The simulation results confirm the theoretical predictions, which state that the transverse orbital angular momentum of the mode not only depends on the frequency of the incident light, but also depends on the transformation scale of the azimuthal angle. Because energy dissipation inevitably reduces the field amplitude of the modes, the confined electromagnetic energy and the quality factor of the modes inside the ring are also studied in order to evaluate the stability of those cavity modes. The results show that the metamaterial ring can effectively confine light with a high quality factor and maintain steady modes with the orbital angular momentum, even if the dimension of the ring is much smaller than the wavelength of the incident light. This technique for exploiting the modes with optical transverse orbital angular momentum may provides a unique platform for applications related to micromanipulation.

  9. Scheme for a compact cold-atom clock based on diffuse laser cooling in a cylindrical cavity

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Meng, Yanling; Wan, Jinyin; Wang, Xiumei; Wang, Yaning; Xiao, Ling; Cheng, Huadong; Liu, Liang

    2015-12-01

    We present a scheme for a compact rubidium cold-atom clock which performs diffuse light cooling, microwave interrogation, and detection of the clock signal in a cylindrical microwave cavity. The diffuse light is produced by laser light reflection at the inner surface of the microwave cavity. The pattern of the injected laser beams is specially designed to accumulate the majority of the cold atoms in the center of the microwave cavity. Microwave interrogation of the cold atoms in the cavity leads to Ramsey fringes, which have a linewidth of 24.5 Hz with a contrast of 95.6 % when the free evolution time is 20 ms. Recently, a frequency stability of 7.3 ×10-13τ-1 /2 has been achieved. The scheme of this physical package can largely reduce the cold-atom clock complexity and increase clock performance.

  10. Length measurement in absolute scale via low-dispersion optical cavity

    NASA Astrophysics Data System (ADS)

    Pravdova, Lenka; Lesundak, Adam; Smid, Radek; Hrabina, Jan; Rerucha, Simon; Cip, Ondrej

    2016-12-01

    We report on the length measuring instrument with the absolute scale that was based on the combination of an optical frequency comb and a passive optical cavity. The time spacing of short femtosecond pulses, generated by the optical frequency comb, is optically phase locked onto the cavity free spectral range with a derivative spectroscopy technique so that the value of the repetition frequency of the femtosecond laser is tied to and determines the measured displacement. The instantaneous value of the femtosecond pulse train frequency is counted by a frequency counter. This counted value corresponds to the length given by the spacing between the two mirrors of the passive cavity. The phase lock between the femtosecond pulsed beam and the passive cavity is possible due to the low-dispersion of the cavity mirrors, where the silver coating on the mirrors was used to provide the low dispersion for the broadband radiation of the comb. Every reflection on the output mirror feeds a portion of the beam back to the cavity so that the output beam is a result of multiple interfering components. The parameters of the output beam are given not only by the parameters of the mirrors but mainly by the absolute distance between the mirror surfaces. Thus, one cavity mirror can be considered as the reference starting point of the distance to be measured and the other mirror is the measuring probe surveying the unknown distance. The measuring mirror of the experimental setup of the low-dispersion cavity is mounted on a piezoelectric actuator which provides small changes in the cavity length we used to test the length measurement method. For the verification of the measurement accuracy a reference incremental interferometer was integrated into our system so that the displacement of the piezoelectric actuator could be obtained with both measuring methods simultaneously.

  11. Fluorescence of semiconductor nanocrystals coupled to optical Tamm cavities

    NASA Astrophysics Data System (ADS)

    Feng, Fu; Pascale Senellart Team; Benoit Dubertret Team; Agnes Maitre Team

    We describe here the photoluminescence properties of a layer of colloidal CdSe/CdS fluorescent nanocrystals embedded in such a Tamm cavity. Spectral and angular analysis of fluorescence shows that the nanocrystals emission is into the Tamm states ; the emission dispersion relation for disks of various diameters shows the effect of the Tamm states lateral confinement. We also combined spatial and angular emission analysis and showed that the direction of emission is not the same for different points on a disk: emission from the left (resp. right) portion of the cavity is directed mostly in the left (resp. right) direction, in agreement with our numerical simulations. Our measurement scheme constitutes a probe of the Tamm state electric field phase gradient inside the cavity. Spatial and K space resolved spectroscopy.

  12. Flight-Like Optical Reference Cavity for GRACE Follow-On Laser Frequency Stabilization

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; deVine, G.; Klipstein, W. M.; McKenzie, K.; Spero, R.; Thompson, R.; Yu, N.; Stephens, M.; Leitch, J.; Pierce, R.; Shaddock, D.; Lam, T.

    2011-01-01

    We describe a prototype optical cavity and associated optics that has been developed to provide a stable frequency reference for a future space-based laser ranging system. This instrument is being considered for inclusion as a technology demonstration on the recently announced GRACE follow-on mission, which will monitor variations in the Earth's gravity field.

  13. Thermo-optical response of photonic crystal cavities operating in the visible spectral range.

    PubMed

    Wolters, Janik; Nikolay, Niko; Schoengen, Max; Schell, Andreas W; Probst, Jürgen; Löchel, Bernd; Benson, Oliver

    2013-08-09

    In this paper we study thermo-optical effects in gallium phosphite photonic crystal cavities in the visible range. By measuring the shift of narrow resonances, we derive the temperature dependency of the local refractive index of gallium phosphide in an attoliter volume over a temperature range between 5 and 300 K at a wavelength of about 605 nm. Additionally, the potential of photonic crystal cavities for thermo-optical switching of visible light is investigated. As an example we demonstrate thermo-optical switching with 13 dB contrast.

  14. Active disturbance rejection control of temperature for ultrastable optical cavities.

    PubMed

    Pizzocaro, Marco; Calonico, Davide; Calosso, Claudio; Clivati, Cecilia; Costanzo, Giovanni A; Levi, Filippo; Mura, Alberto

    2013-02-01

    This paper describes the application of a novel active disturbance rejection control (ADRC) to the stabilization of the temperature of two ultra-stable Fabry-Perot cavities. The cavities are 10 cm long and entirely made of ultralow- expansion glass. The control is based on a linear extended state observer that estimates and compensates the disturbance in the system in real time. The resulting control is inherently robust and easy to tune. A digital implementation of ADRC gives a temperature instability of 200 μK at one day of integration time.

  15. Lateral shearing optical gradient force in coupled nanobeam photonic crystal cavities

    SciTech Connect

    Du, Han; Zhang, Xingwang; Chau, Fook Siong; Zhou, Guangya; Deng, Jie; Zhao, Yunshan

    2016-04-25

    We report the experimental observation of lateral shearing optical gradient forces in nanoelectromechanical systems (NEMS) controlled dual-coupled photonic crystal (PhC) nanobeam cavities. With an on-chip integrated NEMS actuator, the coupled cavities can be mechanically reconfigured in the lateral direction while maintaining a constant coupling gap. Shearing optical gradient forces are generated when the two cavity centers are laterally displaced. In our experiments, positive and negative lateral shearing optical forces of 0.42 nN and 0.29 nN are observed with different pumping modes. This study may broaden the potential applications of the optical gradient force in nanophotonic devices and benefit the future nanooptoelectromechanical systems.

  16. Lateral shearing optical gradient force in coupled nanobeam photonic crystal cavities

    NASA Astrophysics Data System (ADS)

    Du, Han; Zhang, Xingwang; Deng, Jie; Zhao, Yunshan; Chau, Fook Siong; Zhou, Guangya

    2016-04-01

    We report the experimental observation of lateral shearing optical gradient forces in nanoelectromechanical systems (NEMS) controlled dual-coupled photonic crystal (PhC) nanobeam cavities. With an on-chip integrated NEMS actuator, the coupled cavities can be mechanically reconfigured in the lateral direction while maintaining a constant coupling gap. Shearing optical gradient forces are generated when the two cavity centers are laterally displaced. In our experiments, positive and negative lateral shearing optical forces of 0.42 nN and 0.29 nN are observed with different pumping modes. This study may broaden the potential applications of the optical gradient force in nanophotonic devices and benefit the future nanooptoelectromechanical systems.

  17. Three-dimensional Gradient Index Optics Fabricated in Diffusive Photopolymers

    NASA Astrophysics Data System (ADS)

    Ye, Chunfang

    This thesis demonstrates three-dimensional gradient index (GRIN) optics fabricated in two diffusive photopolymers. These polymer optical components have localized gradient index structures, which are self-developed in diffusive photopolymers by introducing localized illuminations. Based on the sizes of the formed index structures, the photopolymer optics studied in this thesis fall into two categories: GRIN lens based optics and waveguide based optics. GRIN lenses and lens arrays with parabolic index profiles are created through Gaussian beam exposure, while GRIN lenses with arbitrary index profiles are created through a dual-axis galvo scanning system. Waveguide based optics, which include uniform waveguides, waveguide tapers, waveguides through thin optics and 900 sharp waveguide bends, are fabricated through direct-write lithography. Several quantitative characterization methods for the fabricated polymer optics are described. The index profiles of the GRIN lens based optics are quantitatively measured by a modified scanning transmission phase microscope and a Shack-Hartmann wavefront sensor. Three-dimensional mode profile characterization of the polymer waveguides is carried out through a novel polymer sample preparation procedure and an active mode imaging system. A single mode performance is confirmed for the fabricated waveguides. A loss measurement for the waveguides is also accomplished. An index formation model is developed for a diffusive polymer developed by Dr. McLeod's group, which provides a fundamental guidance for fabricating custom-design index structures in the polymer. A hybrid GRIN axicon lens is fabricated to significantly extend the depth of focus in an endoscopy OCT application. Potential applications of the fabricated polymer optics include hybrid integrated optical circuits. The diffusive photopolymer with self-development characteristics provides a platform to integrate various optoelectronic subcomponents in integrated optical circuits.

  18. Comparison of diffusion approximation and higher order diffusion equations for optical tomography of osteoarthritis

    NASA Astrophysics Data System (ADS)

    Yuan, Zhen; Zhang, Qizhi; Sobel, Eric; Jiang, Huabei

    2009-09-01

    In this study, a simplified spherical harmonics approximated higher order diffusion model is employed for 3-D diffuse optical tomography of osteoarthritis in the finger joints. We find that the use of a higher-order diffusion model in a stand-alone framework provides significant improvement in reconstruction accuracy over the diffusion approximation model. However, we also find that this is not the case in the image-guided setting when spatial prior knowledge from x-rays is incorporated. The results show that the reconstruction error between these two models is about 15 and 4%, respectively, for stand-alone and image-guided frameworks.

  19. Modeling of multi-cavity Fabry-Perot optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Wierzba, Paweł

    2015-12-01

    Reflectance characteristics of a two-cavity extrinsic Fabry-Perot optical fiber sensor were investigated using computer modeling. Calculations were performed using a plane wave-based approach, selected for clarity of results. Based on the modeling results, it can be concluded that the two-cavity Fabry-Perot interferometer can be used to measure two different quantities, such as refractive index and temperature, independently. It is also possible to use one of its cavities as a wavelength or optical path length reference, especially when a tunable laser is used as a light source. Spectral signal processing needed in such sensor is not substantially more complicated than that used in single cavity sensors.

  20. Demonstration of the stabilization technique for nonplanar optical resonant cavities utilizing polarization

    SciTech Connect

    Akagi, T.; Araki, S.; Funahashi, Y.; Honda, Y.; Okugi, T.; Omori, T.; Shimizu, H.; Terunuma, N.; Urakawa, J.; Miyoshi, S.; Takahashi, T. Tanaka, R.; Uesugi, Y.; Yoshitama, H.; Sakaue, K.; Washio, M.

    2015-04-15

    Based on our previously developed scheme to stabilize nonplanar optical resonant cavities utilizing polarization caused by a geometric phase in electromagnetic waves traveling along a twisted path, we report an application of the technique for a cavity installed in the Accelerator Test Facility, a 1.3-GeV electron beam accelerator at KEK, in which photons are generated by laser-Compton scattering. We successfully achieved a power enhancement of 1200 with 1.4% fluctuation, which means that the optical path length of the cavity has been controlled with a precision of 14 pm under an accelerator environment. In addition, polarization switching utilizing a geometric phase of the nonplanar cavity was demonstrated.

  1. High-Q silica zipper cavity for optical radiation pressure driven MOMS switch

    SciTech Connect

    Tetsumoto, Tomohiro; Tanabe, Takasumi

    2014-07-15

    We design a silica zipper cavity that has high optical and mechanical Q (quality factor) values and demonstrate numerically the feasibility of a radiation pressure driven micro opto-mechanical system (MOMS) directional switch. The silica zipper cavity has an optical Q of 4.0 × 10{sup 4} and an effective mode volume V{sub mode} of 0.67λ{sup 3} when the gap between two cavities is 34 nm. The mechanical Q (Q{sub m}) is determined by thermo-elastic damping and is 2.0 × 10{sup 6} in a vacuum at room temperature. The opto-mechanical coupling rate g{sub OM} is as high as 100 GHz/nm, which allows us to move the directional cavity-waveguide system and switch 1550-nm light with 770-nm light by controlling the radiation pressure.

  2. Optical nanofiber-based cavity induced by periodic air-nanohole arrays

    NASA Astrophysics Data System (ADS)

    Li, Wenfang; Du, Jinjin; Truong, Viet Giang; Nic Chormaic, Síle

    2017-06-01

    We experimentally realized an optical nanofiber-based cavity by combining a 1-D photonic crystal and Bragg grating structures. The cavity morphology comprises a periodic, triplex air-cube introduced at the waist of the nanofiber. The cavity has been theoretically characterized using finite-difference time-domain simulations to obtain the reflection and transmission spectra. We have also experimentally measured the transmission spectra, and a Q-factor of ˜784 ± 87 for a very short periodic structure has been observed. The structure provides strong confinement of the cavity field, and its potential for optical network integration makes it an ideal candidate for use in nanophotonic and quantum information systems.

  3. Magnetically Induced Optical Transparency on a Forbidden Transition in Strontium for Cavity-Enhanced Spectroscopy

    NASA Astrophysics Data System (ADS)

    Winchester, Matthew N.; Norcia, Matthew A.; Cline, Julia R. K.; Thompson, James K.

    2017-06-01

    In this Letter we realize a narrow spectroscopic feature using a technique that we refer to as magnetically induced optical transparency. A cold ensemble of 88Sr atoms interacts with a single mode of a high-finesse optical cavity via the 7.5 kHz linewidth, spin forbidden 1S0 to 3P1 transition. By applying a magnetic field that shifts two excited state Zeeman levels, we open a transmission window through the cavity where the collective vacuum Rabi splitting due to a single level would create destructive interference for probe transmission. The spectroscopic feature approaches the atomic transition linewidth, which is much narrower than the cavity linewidth, and is highly immune to the reference cavity length fluctuations that limit current state-of-the-art laser frequency stability.

  4. In situ characterization of an optically thick atom-filled cavity

    NASA Astrophysics Data System (ADS)

    Munns, J. H. D.; Qiu, C.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.; Saunders, D. J.

    2016-01-01

    A means for precise experimental characterization of the dielectric susceptibility of an atomic gas inside an optical cavity is important for the design and operation of quantum light-matter interfaces, particularly in the context of quantum information processing. Here we present a numerically optimized theoretical model to predict the spectral response of an atom-filled cavity, accounting for both homogeneous and inhomogeneous broadening at high optical densities. We investigate the regime where the two broadening mechanisms are of similar magnitude, which makes the use of common approximations invalid. Our model agrees with an experimental implementation with warm caesium vapor in a ring cavity. From the cavity response, we are able to extract important experimental parameters, for instance the ground-state populations, total number density, and the magnitudes of both homogeneous and inhomogeneous broadening.

  5. New limit on Lorentz violation using a double-pass optical ring cavity.

    PubMed

    Michimura, Yuta; Matsumoto, Nobuyuki; Ohmae, Noriaki; Kokuyama, Wataru; Aso, Yoichi; Ando, Masaki; Tsubono, Kimio

    2013-05-17

    A search for Lorentz violation in electrodynamics was performed by measuring the resonant frequency difference between two counterpropagating directions of an optical ring cavity. Our cavity contains a dielectric element, which makes our cavity sensitive to the violation. The laser frequency is stabilized to the counterclockwise resonance of the cavity, and the transmitted light is reflected back into the cavity for resonant frequency comparison with the clockwise resonance. This double-pass configuration enables a null experiment and gives high common mode rejection of environmental disturbances. We found no evidence for odd-parity anisotropy at the level of δc/c ≲ 10(-14). Within the framework of the standard model extension, our result put more than 5 times better limits on three odd-parity parameters κ(o+)(JK) and a 12 times better limit on the scalar parameter κ(tr) compared with the previous best limits.

  6. [The videoendoscopic sanation of the abdominal cavity by the diffuse septic peritonitis].

    PubMed

    Sukovatykh, B S; Blinkov, Iu Iu; Ivanov, P A

    2012-01-01

    The 1st group consisted of 68 patients with the diffuse peritonitis, who were treated with the use of traditional approach, i.e., laparotomy, elimination of the peritonitis source, nasointestinal intubation, abdominal cavity sanation and drainage. Within 24--48 hours all these patients had videoendoscopic abdominal sanation with the injection of 200 ml 0.03% water solution of sodium hypochlorite. The 2nd group, consisted of 41 patients. The first treatment stage was the same, but during the videoendoscopic stage the pulsing stream of the antiseptic was used and the procedure ended with intraabdominal injection of 200 ml 0.03% water solution of sodium hypochlorite immobilized in gel. All patients of the 2nd group showed better recovery results.

  7. Development of Nb{sub 3}Sn Cavity Vapor Diffusion Deposition System

    SciTech Connect

    Eremeev, Grigory V.; Macha, Kurt M.; Clemens, William A.; Park, HyeKyoung; Williams, R. Scott

    2014-02-01

    Nb{sub 3}Sn is a BCS superconductors with the superconducting critical temperature higher than that of niobium, so theoretically it surpasses the limitations of niobium in RF fields. The feasibility of technology has been demonstrated at 1.5 GHz with Nb{sub 3}Sn vapor deposition technique at Wuppertal University. The benefit at these frequencies is more pronounced at 4.2 K, where Nb{sub 3}Sn coated cavities show RF resistances an order of magnitude lower than that of niobium. At Jefferson Lab we started the development of Nb{sub 3}Sn vapor diffusion deposition system within an R\\&D development program towards compact light sources. Here we present the current progress of the system development.

  8. Hybrid radiative-transfer-diffusion model for optical tomography

    NASA Astrophysics Data System (ADS)

    Tarvainen, Tanja; Vauhkonen, Marko; Kolehmainen, Ville; Kaipio, Jari P.

    2005-02-01

    A hybrid radiative-transfer-diffusion model for optical tomography is proposed. The light propagation is modeled with the radiative-transfer equation in the vicinity of the laser sources, and the diffusion approximation is used elsewhere in the domain. The solution of the radiative-transfer equation is used to construct a Dirichlet boundary condition for the diffusion approximation on a fictitious interface within the object. This boundary condition constitutes an approximative distributed source model for the diffusion approximation in the remaining area. The results from the proposed approach are compared with finite-element solutions of the radiative-transfer equation and the diffusion approximation and Monte Carlo simulation. The results show that the method improves the accuracy of the forward model compared with the conventional diffusion model.

  9. XTREME OPTICS: the behavior of cavity optics for the Jefferson Lab free-electron laser

    SciTech Connect

    Michelle D. Shinn; Christopher Behre; Stephen Benson; David Douglas; Fred Dylla; Christopher Gould; Joseph Gubeli; David Hardy; Kevin Jordan; George Neil; and Shukui Zhanga

    2006-09-25

    The cavity optics within high power free-electron lasers based on energy-recovering accelerators are subjected to extreme conditions associated with illumination from a broad spectrum of radiation, often at high irradiances. This is especially true for the output coupler, where absorption of radiation by both the mirror substrate and coating places significant design restrictions to properly manage heat load and prevent mirror distortion. Besides the fundamental lasing wavelength, the mirrors are irradiated with light at harmonics of the fundamental, THz radiation generated by the bending magnets downstream of the wiggler, and x-rays produced when the electron beam strikes accelerator diagnostic components (e.g., wire scanners and view screens) or from inadvertent beam loss. The optics must reside within high vacuum at ~ 10-8 Torr and this requirement introduces its own set of complications. This talk discusses the performance of numerous high reflector and output coupler optics assemblies and provides a detailed list of lessons learned gleaned from years of experience operating the Upgrade IR FEL, a 10 kW-class, sub-ps laser with output wavelength from 1 to 6 microns.

  10. Generation and purification of maximally entangled atomic states in optical cavities

    SciTech Connect

    Lougovski, P.; Walther, H.; Solano, E.

    2005-01-01

    We present a probabilistic scheme for generating and purifying maximally entangled states of two atoms inside an optical cavity via no-photon detection at the cavity output, where ideal detectors are not required. The intermediate mixed states can be continuously purified so as to violate Bell inequalities in a parametrized manner. The scheme relies on an additional strong-driving field that realizes, atypically, simultaneous Jaynes-Cummings and anti-Jaynes-Cummings interactions.

  11. In situ observation of optomechanical Bloch oscillations in an optical cavity

    NASA Astrophysics Data System (ADS)

    Keßler, H.; Klinder, J.; Prasanna Venkatesh, B.; Georges, Ch; Hemmerich, A.

    2016-10-01

    It is shown experimentally that a Bose-Einstein condensate inside an optical cavity, operating in the regime of strong cooperative coupling, responds to an external force by an optomechanical Bloch oscillation, which can be directly observed in the light leaking out of the cavity. Previous theoretical work predicts that the frequency of this oscillation matches with that of conventional Bloch oscillations such that its in situ monitoring may help to increase the data acquisition speed in precision force measurements.

  12. Enhanced photocoagulation with catheter-based diffusing optical device

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Kim, Jeehyun; Oh, Jungwhan

    2012-11-01

    A novel balloon catheter-based diffusing optical device was designed and evaluated to assist in treating excessive menstrual bleeding. A synthetic fused-silica fiber was micro-machined precisely to create scattering segments on a 25 mm long fiber tip for uniform light distribution. A visible wavelength (λ=532 nm) was used to specifically target the endometrium due to the high vascularity of the uterine wall. Optical simulation presented 30% wider distribution of photons along with approximately 40% higher irradiance induced by addition of a glass cap to the diffuser tip. Incorporation of the optical diffuser with a polyurethane balloon catheter considerably enhanced coagulation depth and area (i.e., 3.5 mm and 18.9 cm2 at 1 min irradiation) in tissue in vitro. The prototype device demonstrated the coagulation necrosis of 2.8±1.2 mm (n=18) and no thermal damage to myometrium in in vivo caprine models. A prototype 5 cm long balloon catheter-assisted optical diffuser was also evaluated with a cadaveric human uterus to confirm the coagulative response of the uterine tissue as well as to identify the further design improvement and clinical applicability. The proposed catheter-based diffusing optical device can be a feasible therapeutic tool to photocoagulate endometrial cell layers in an efficient and safe manner.

  13. Collective atomic motion and spin dynamics in a driven optical cavity

    NASA Astrophysics Data System (ADS)

    Stamper-Kurn, Dan

    2016-05-01

    Cavity quantum electrodynamics generally highlights the interchange of quantum noise and information between light and matter. I will discuss experiments in which the collective motion and spin of a trapped gas of ultracold atoms interact with and are detected by light in a single mode of a high-finesse optical cavity. I will present recent results on quantum-limited force detection, on the damping and amplification of Larmor precession through dynamical backaction, and on cavity-induced coupling between mechanical oscillators and between spin and motional degrees of freedom.

  14. Adiabatic transfer of energy fluctuations between membranes inside an optical cavity

    NASA Astrophysics Data System (ADS)

    Garg, Devender; Chauhan, Anil K.; Biswas, Asoka

    2017-08-01

    A scheme is presented for the adiabatic transfer of average fluctuations in the phonon number between two membranes in an optical cavity. We show that by driving the cavity modes with external time-delayed pulses, one can obtain an effect analogous to stimulated Raman adiabatic passage in the atomic systems. The adiabatic transfer of fluctuations from one membrane to the other is attained through a "dark" mode, which is robust against decay of the mediating cavity mode. The results are supported with analytical and numerical calculations with experimentally feasible parameters.

  15. Photon Emission and Absorption of a Single Ion Coupled to an Optical-Fiber Cavity

    NASA Astrophysics Data System (ADS)

    Steiner, M.; Meyer, H. M.; Reichel, J.; Köhl, M.

    2014-12-01

    We present a light-matter interface which consists of a single 174Yb+ ion coupled to an optical fiber cavity. We observe that photons at 935 nm are mainly emitted into the cavity mode and that correlations between the polarization of the photon and the spin state of the ion are preserved despite the intrinsic coupling into a single-mode fiber. Complementary, when a faint coherent light field is injected into the cavity mode, we find enhanced and polarization dependent absorption by the ion.

  16. Dynamically Manipulating Topological Physics and Edge Modes in a Single Degenerate Optical Cavity.

    PubMed

    Zhou, Xiang-Fa; Luo, Xi-Wang; Wang, Su; Guo, Guang-Can; Zhou, Xingxiang; Pu, Han; Zhou, Zheng-Wei

    2017-02-24

    We propose a scheme to simulate topological physics within a single degenerate cavity, whose modes are mapped to lattice sites. A crucial ingredient of the scheme is to construct a sharp boundary so that the open boundary condition can be implemented for this effective lattice system. In doing so, the topological properties of the system can manifest themselves on the edge states, which can be probed from the spectrum of an output cavity field. We demonstrate this with two examples: a static Su-Schrieffer-Heeger chain and a periodically driven Floquet topological insulator. Our work opens up new avenues to explore exotic photonic topological phases inside a single optical cavity.

  17. Dynamically Manipulating Topological Physics and Edge Modes in a Single Degenerate Optical Cavity

    NASA Astrophysics Data System (ADS)

    Zhou, Xiang-Fa; Luo, Xi-Wang; Wang, Su; Guo, Guang-Can; Zhou, Xingxiang; Pu, Han; Zhou, Zheng-Wei

    2017-02-01

    We propose a scheme to simulate topological physics within a single degenerate cavity, whose modes are mapped to lattice sites. A crucial ingredient of the scheme is to construct a sharp boundary so that the open boundary condition can be implemented for this effective lattice system. In doing so, the topological properties of the system can manifest themselves on the edge states, which can be probed from the spectrum of an output cavity field. We demonstrate this with two examples: a static Su-Schrieffer-Heeger chain and a periodically driven Floquet topological insulator. Our work opens up new avenues to explore exotic photonic topological phases inside a single optical cavity.

  18. Polymer-based Photonic Crystal Cavity Sensor for Optical Detection in the Visible Wavelength Region.

    PubMed

    Maeno, Kenichi; Aki, Shoma; Sueyoshi, Kenji; Hisamoto, Hideaki; Endo, Tatsuro

    2016-01-01

    In this study, a polymer-based two-dimensional photonic crystal (PhC) cavity for visible-light-based optical-sensing applications was designed and fabricated for the first time. The PhC cavity configuration was designed to operate at 650 nm, and fabricated with a polymer (resist) on a silicon substrate using electron-beam lithography. For investigating sensing applications based on shifting of condition exhibiting a photonic bandgap (PBG), the polymer monolayer deposition (layer-by-layer method) was monitored as the light-intensity change at the cavity position. Consequently, the monolayer-level detection of polyions was achieved.

  19. Modeling of optically controlled reflective bistability in a vertical cavity semiconductor saturable absorber

    NASA Astrophysics Data System (ADS)

    Mishra, L.

    2015-05-01

    Bistability switching between two optical signals has been studied theoretically utilizing the concept of cross absorption modulation in a vertical cavity semiconductor saturable absorber (VCSSA). The probe beam is fixed at a wavelength other than the low power cavity resonance wavelength, which exhibits bistable characteristic by controlling the power of a pump beam (λpump≠λprobe). The cavity nonlinear effects that arises simultaneously from the excitonic absorption bleaching, and the carrier induced nonlinear index change has been considered in the model. The high power absorption in the active region introduces thermal effects within the nonlinear cavity due to which the effective cavity length changes. This leads to a red-shift of the cavity resonance wavelength, which results a change in phase of the optical fields within the cavity. In the simulation, the phase-change due to this resonance shifting is considered to be constant over time, and it assumes the value corresponding to the maximum input power. Further, an initial phase detuning of the probe beam has been considered to investigate its effect on switching. It is observed from the simulated results that, the output of the probe beam exhibits either clockwise or counter-clockwise bistability, depending on its initial phase detuning.

  20. Non-adiabatic dynamics of molecules in optical cavities

    SciTech Connect

    Kowalewski, Markus Bennett, Kochise; Mukamel, Shaul

    2016-02-07

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  1. Non-adiabatic dynamics of molecules in optical cavities

    NASA Astrophysics Data System (ADS)

    Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul

    2016-02-01

    Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.

  2. Two-Photon Cavity Solitons in Active Optical Media

    SciTech Connect

    Vilaseca, R.; Torrent, M. C.; Garcia-Ojalvo, J.; Brambilla, M.; San Miguel, M.

    2001-08-20

    We show that broad-area cascade lasers with no absorbing intracavity elements support the spontaneous formation of two-dimensional bright localized structures in a dark background. These cavity solitons consist of islands of two-photon emission embedded in a background of single-photon emission. We discuss the mechanisms through which these structures are formed and interact, along with their properties and stability.

  3. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    NASA Astrophysics Data System (ADS)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  4. Negative response with an optical cavity and traveling wave fields

    NASA Astrophysics Data System (ADS)

    de Assis, R. J.; Villas-Boas, C. J.; de Almeida, N. G.

    2017-07-01

    We present a feasible protocol using a traveling wave field to experimentally observe a negative response, i.e., to obtain a decrease in the output field intensity when the input field intensity is increased. Our protocol uses one beam splitter and two mirrors to direct the traveling wave field into a lossy cavity in which there is a three-level atom in a Λ configuration. In our scheme, the input field impinges on a beam splitter and, while the transmitted part is used to drive the cavity mode, the reflected part is used as the control field to obtain a negative response of the output field. We show that the greater the cooperativity of the atom-cavity system, the more pronounced the negative response. The system we are proposing can be used to protect devices sensitive to intense fields, since the intensity of the output field, which should be directed to the device to be protected, is diminished when the intensity of the input field increases.

  5. Single-shot optical readout of a quantum bit using cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Sun, Shuo; Waks, Edo

    2016-07-01

    We propose a method to perform single-shot optical readout of a quantum bit (qubit) using cavity quantum electrodynamics. We selectively couple the optical transitions associated with different qubit basis states to the cavity and utilize the change in cavity transmissivity to generate a qubit readout signal composed of many photons. We show that this approach enables single-shot optical readout even when the qubit does not have a good cycling transition, which is required for standard resonance fluorescence measurements. We calculate the probability that the measurement detects the correct qubit state using the example of a quantum-dot spin under various experimental conditions and demonstrate that it can exceed 0.99.

  6. Alignment sensing for optical cavities using radio-frequency jitter modulation.

    PubMed

    Fulda, P; Voss, D; Mueller, C; Ortega, L F; Ciani, G; Mueller, G; Tanner, D B

    2017-05-01

    Alignment sensing is often required in precision interferometry applications such as Advanced LIGO in order to achieve the optimum performance. Currently favored sensing schemes rely on the use of two separate radio-frequency (RF) quadrant photodetectors and Gouy phase telescopes to determine the alignment of a beam relative to an optical cavity axis. In this paper, we demonstrate an alternative sensing scheme that has potential advantages over the current standard schemes. We show that by using electro-optic beam deflectors to impose RF jitter sidebands on a beam, it is possible to extract full alignment signals for two in-line optical cavities from just one single-element photodetector in reflection of each cavity.

  7. Extreme nonlinear response of ultranarrow optical transitions in cavity QED for laser stabilization

    SciTech Connect

    Martin, M. J.; Meiser, D.; Ye Jun; Holland, M. J.; Thomsen, J. W.

    2011-12-15

    We explore the potential of direct spectroscopy of ultranarrow optical transitions of atoms localized in an optical cavity. In contrast to stabilization against a reference cavity, which is the approach currently used for the most highly stabilized lasers, stabilization against an atomic transition does not suffer from Brownian thermal noise. Spectroscopy of ultranarrow optical transitions in a cavity operates in a very highly saturated regime in which nonlinear effects such as bistability play an important role. From the universal behavior of the Jaynes-Cummings model with dissipation, we derive the fundamental limits for laser stabilization using direct spectroscopy of ultranarrow atomic lines. We find that, with current lattice clock experiments, laser linewidths of about 1 mHz can be achieved in principle, and the ultimate limitations of this technique are at the 1 {mu}Hz level.

  8. Thermal analysis of optical reference cavities for low sensitivity to environmental temperature fluctuations.

    PubMed

    Dai, Xiaojiao; Jiang, Yanyi; Hang, Chao; Bi, Zhiyi; Ma, Longsheng

    2015-02-23

    The temperature stability of optical reference cavities is significant in state-of-the-art ultra-stable narrow-linewidth laser systems. In this paper, the thermal time constant and thermal sensitivity of reference cavities are analyzed when reference cavities respond to environmental perturbations via heat transfer of thermal conduction and thermal radiation separately. The analysis as well as simulation results indicate that a reference cavity enclosed in multiple layers of thermal shields with larger mass, higher thermal capacity and lower emissivity is found to have a larger thermal time constant and thus a smaller sensitivity to environmental temperature perturbations. The design of thermal shields for reference cavities may vary according to experimentally achievable temperature stability and the coefficient of thermal expansion of reference cavities. A temperature fluctuation-induced length instability of reference cavities as low as 6 × 10(-16) on a day timescale can be achieved if a two-layer thermal shield is inserted between a cavity with the coefficient of thermal expansion of 1 × 10(-10) /K and an outer vacuum chamber with temperature fluctuation amplitude of 1 mK and period of 24 hours.

  9. Optical-bistability-enabled control of resonant light transmission for an atom-cavity system

    NASA Astrophysics Data System (ADS)

    Sawant, Rahul; Rangwala, S. A.

    2016-02-01

    The control of light transmission through a standing-wave Fabry-Pérot cavity containing atoms is theoretically and numerically investigated, when the cavity mode beam and an intersecting control beam are both close to specific atomic resonances. A four-level atomic system is considered and its interaction with the cavity mode is studied by solving for the cavity field and atomic state populations. The conditions for optical bistability of the atom-cavity system are obtained. The response of the intracavity intensity to an intersecting beam on atomic resonance is understood in the presence of stationary atoms (closed system) and nonstatic atoms (open system) in the cavity. The nonstatic system of atoms is modelled by adjusting the atomic state populations to represent the exchange of atoms in the cavity mode, which corresponds to a thermal environment where atoms are moving in and out of the cavity mode volume. The control behavior with three- and two-level atomic systems is also studied, and the rich physics arising out of these systems for closed and open atomic systems is discussed. The solutions to the models are used to interpret the steady-state and transient behavior observed by Sharma et al. [Phys. Rev. A 91, 043824 (2015)], 10.1103/PhysRevA.91.043824.

  10. Novel laser machining of optical fibers for long cavities with low birefringence.

    PubMed

    Takahashi, Hiroki; Morphew, Jack; Oručević, Fedja; Noguchi, Atsushi; Kassa, Ezra; Keller, Matthias

    2014-12-15

    We present a novel method of machining optical fiber surfaces with a CO₂ laser for use in Fiber-based Fabry-Perot Cavities (FFPCs). Previously FFPCs were prone to large birefringence and limited to relatively short cavity lengths (≤ 200 μm). These characteristics hinder their use in some applications such as cavity quantum electrodynamics with trapped ions. We optimized the laser machining process to produce large, uniform surface structures. This enables the cavities to achieve high finesse even for long cavity lengths. By rotating the fibers around their axis during the laser machining process the asymmetry resulting from the laser's transverse mode profile is eliminated. Consequently we are able to fabricate fiber mirrors with a high degree of rotational symmetry, leading to remarkably low birefringence. Through measurements of the cavity finesse over a range of cavity lengths and the polarization dependence of the cavity linewidth, we confirmed the quality of the produced fiber mirrors for use in low-birefringence FFPCs.

  11. The relevance of light diffusion profiles for interstitial PDT using light-diffusing optical fibers

    NASA Astrophysics Data System (ADS)

    Stringasci, Mirian D.; Fortunato, Thereza C.; Moriyama, Lilian T.; Vollet Filho, José Dirceu; Bagnato, Vanderlei S.; Kurachi, Cristina

    2017-02-01

    Photodynamic therapy (PDT) is a technique used for several tumor types treatment. Light penetration on biological tissue is one limiting factor for PDT applied to large tumors. An alternative is using interstitial PDT, in which optical fibers are inserted into tumors. Cylindrical diffusers have been used in interstitial PDT. Light emission of different diffusers depends on the manufacturing process, size and optical properties of fibers, which make difficult to establish an adequate light dosimetry, since usually light profile is not designed for direct tissue-fiber contact. This study discusses the relevance of light distribution by a cylindrical diffuser into a turbid lipid emulsion solution, and how parts of a single diffuser contribute to illumination. A 2 cm-long cylindrical diffuser optical fiber was connected to a diode laser (630 nm), and the light spatial distribution was measured by scanning the solution with a collection probe. From the light field profile generated by a 1 mm-long intermediary element of a 20 mm-long cylindrical diffuser, recovery of light distribution for the entire diffuser was obtained. PDT was performed in rat healthy liver for a real treatment outcome analysis. By using computational tools, a typical necrosis profile generated by the irradiation with such a diffuser fiber was reconstructed. The results showed that it was possible predicting theoretically the shape of a necrosis profile in a healthy, homogeneous tissue with reasonable accuracy. The ability to predict the necrosis profile obtained from an interstitial illumination by optical diffusers has the potential improve light dosimetry for interstitial PDT.

  12. Thermal-wave resonator cavity design and measurements of the thermal diffusivity of liquids

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.; Mandelis, A.; Garcia, J. A.

    2000-07-01

    A liquid-ambient-compatible thermal wave resonant cavity (TWRC) has been constructed for the measurement of the thermal diffusivity of liquids. The thermal diffusivities of distilled water, glycerol, ethylene glycol, and olive oil were determined at room temperature (25 °C), with four-significant-figure precision as follows: (0.1445±0.0002)×10-2 cm2/s (distilled water); (0.0922±0.0002)×10-2 cm2/s (glycerol); (0.0918±0.0002)×10-2 cm2/s (ethylene glycol); and (0.0881±0.0004)×10-2 cm2/s (olive oil). The liquid-state TWRC sensor was found to be highly sensitive to various mixtures of methanol and salt in distilled water with sensitivity limits 0.5% (v/v) and 0.03% (w/v), respectively. The use of the TWRC to measure gas evolution from liquids and its potential for environmental applications has also been demonstrated.

  13. All-dielectric resonant cavity-enabled metals with broadband optical transparency

    NASA Astrophysics Data System (ADS)

    Liu, Zhengqi; Zhang, Houjiao; Liu, Xiaoshan; Pan, Pingping; Liu, Yi; Tang, Li; Liu, Guiqiang

    2017-06-01

    Metal films with broadband optical transparency are desirable in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and infrared detectors. As bare metal is opaque to light, this issue of transparency attracts great scientific interest. In this work, we proposed and demonstrated a feasible and universal approach for achieving broadband optical transparent (BOT) metals by utilizing all-dielectric resonant cavities. Resonant dielectrics provide optical cavity modes and couple strongly with the surface plasmons of the metal film, and therefore produce a broadband near-unity optical transparent window. The relative enhancement factor (EF) of light transmission exceeds 3400% in comparison with that of pure metal film. Moreover, the transparent metal motif can be realized by other common metals including gold (Au), silver (Ag) and copper (Cu). These optical features together with the fully retained electric and mechanical properties of a natural metal suggest that it will have wide applications in optoelectronic devices.

  14. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    SciTech Connect

    Frougier, J. Jaffrès, H.; Deranlot, C.; George, J.-M.; Baili, G.; Dolfi, D.; Alouini, M.; Sagnes, I.; Garnache, A.

    2013-12-16

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

  15. Computational analysis of endometrial photocoagulation with diffusing optical device.

    PubMed

    Kwon, Jinhee; Lee, Chang-Yong; Oh, Junghwan; Kang, Hyun Wook

    2013-01-01

    A balloon-catheter optical diffuser for endometrial treatment was evaluated with computational thermal analysis. Various catheter materials and dimensions were implemented to identify the optimal design for the device. Spatial and temporal development of temperature during 30-sec irradiation of 532-nm light demonstrated thermal insulation effects of polyurethane on temperature increase up to 384 K, facilitating the irreversible denaturation. The current model revealed the degree of thermal coagulation 13% thicker than experimental results possibly due to lack of tissue dynamics and light intensity distribution. In combination with photon distribution, the analytical simulation can be a feasible tool to optimize the new optical diffuser for efficient and safe endometrial treatment.

  16. Depth selective diffuse optical computed topography: simulations and phantom experiments

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Kawanaka, A.; Nakayama, K.

    2007-07-01

    Diffuse optical topography has excellent features as a noninvasive method that provides 2D location information of cortical activity. However, it cannot distinguish the activation depth. We propose an image reconstruction algorithm that suppresses undesirable effects of skin circulation. It comprises a filtering algorithm that extracts target signals from observation data contaminated by disturbing signals and a 2D visualizing process. Computer simulations revealed its excellent performance. We developed a depth selective diffuse optical topography system prototype and performed phantom experiments. Our algorithm significantly suppressed the influence of the disturbing body in the shallow plane with minimal degradation of the target signal.

  17. Normal-mode coupling of rare-earth-metal ions in a crystal to a macroscopic optical cavity mode

    NASA Astrophysics Data System (ADS)

    Ichimura, Kouichi; Goto, Hayato

    2006-09-01

    We demonstrated coupling of rare-earth-metal ions in a crystal to a macroscopic cavity mode by observing optical bistability and normal-mode peaks due to sweeping-laser-induced population redistribution of the ions. The experimentally evaluated coupling constant between the individual ions and the single cavity mode is 15kHz , which is comparable with or larger than the dissipation of the ions and will exceed the cavity dissipation with a narrowing of the mode waist of the cavity to the wavelength. The results advance the application of a coupled system of rare-earth-metal ions in a crystal and an optical cavity for quantum information processing.

  18. Whispering Gallery Mode Resonators as Optical Reference Cavities

    NASA Technical Reports Server (NTRS)

    Baumgartel, Lukas; Thompson, Rob; Strekalov, Dmitry; Grudinin, Ivan; Yu, Nan

    2011-01-01

    Highly stabilized lasers are an increasingly valuable tool for metrology. For many applications, however, existing Fabry Perot systems are too bulky and cumbersome. We are investigating the use of miniature monolithic whispering gallery mode resonators as reference cavities for laser stabilization. We seek to exploit the benefit of small size and vibration resistance by suppressing thermally induced frequency fluctuations. We have theoretically investigated the viability of using a thin-film coating to achieve temperature compensation. We have experimentally investigated an active temperature stabilization scheme based on birefringence in a crystalline resonator. We also report progress of laser locking to the resonators.

  19. Optical glucose monitoring using vertical cavity surface emitting lasers (VCSELs)

    NASA Astrophysics Data System (ADS)

    Talebi Fard, Sahba; Hofmann, Werner; Talebi Fard, Pouria; Kwok, Ezra; Amann, Markus-Christian; Chrostowski, Lukas

    2009-08-01

    Diabetes Mellitus is a common chronic disease that has become a public health issue. Continuous glucose monitoring improves patient health by stabilizing the glucose levels. Optical methods are one of the painless and promising methods that can be used for blood glucose predictions. However, having accuracies lower than what is acceptable clinically has been a major concern. Using lasers along with multivariate techniques such as Partial Least Square (PLS) can improve glucose predictions. This research involves investigations for developing a novel optical system for accurate glucose predictions, which leads to the development of a small, low power, implantable optical sensor for diabetes patients.

  20. Monolithically integrated vertical-cavity lasers and resonant detectors for free-space optical interconnects

    NASA Astrophysics Data System (ADS)

    Louderback, Duane Alan

    In this dissertation, a new technique for integrating vertical cavity lasers and resonant-cavity photodetectors for free-space optical interconnects is explored. The work starts with an overview of the device requirements for free-space optical interconnects, specifically the need for integrated VCLs and detectors that are compatible with flip-chip bonding and microlens integration. The lack of a suitable integration technique lead to the development of a new method of integrating VCLs and detectors. Part of the VCL bottom mirror is oxidized, while the detector structure is left unoxidized, enabling different bottom mirror reflectivities to be achieved. This difference in bottom mirror reflectivity allows individually designed VCLs and resonant-cavity detectors to be monolithically integrated. Since the reflectivity difference is realized in the bottom mirror, the devices have through-the substrate emission and detection, making flip-chip bonding and microlens integration straightforward. High performance VCLs and resonant-cavity detectors were fabricated using this integration technique. A comprehensive analysis of the devices is performed with the goal of broadening the detector optical bandwidth without causing adverse effects on other device parameters. DC and high-speed device characteristics are presented, including the results of a free-space optical link where the operating temperature of the VCL and detector were independently varied over a wide range. These results demonstrate the potential of this integration technique for meeting the device requirements of free-space optical interconnect systems.

  1. Transportable cavity-stabilized laser system for optical carrier frequency transmission experiments.

    PubMed

    Parker, B; Marra, G; Johnson, L A M; Margolis, H S; Webster, S A; Wright, L; Lea, S N; Gill, P; Bayvel, P

    2014-12-10

    We report the design and performance of a transportable laser system at 1543 nm, together with its application as the source for a demonstration of optical carrier frequency transmission over 118 km of an installed dark fiber network. The laser system is based around an optical reference cavity featuring an elastic mounting that bonds the cavity to its support, enabling the cavity to be transported without additional clamping. The cavity exhibits passive fractional frequency insensitivity to vibration along the optical axis of 2.0×10(-11)  m(-1) s(2). With active fiber noise cancellation, the optical carrier frequency transmission achieves a fractional frequency instability, measured at the user end, of 2.6×10(-16) at 1 s, averaging down to below 3×10(-18) after 20,000 s. The fractional frequency accuracy of the transfer is better than 3×10(-18). This level of performance is sufficient for comparison of state-of-the-art optical frequency standards and is achieved in an urban fiber environment.

  2. Quantum memory and phase gate in Optical cavities based on EIT

    NASA Astrophysics Data System (ADS)

    Borges, Halyne; Villas-Bôas, Celso

    In this work we investigate theoretically the implementation of an optical quantum memory in a system composed by a single atom, trapped in a high finesse optical cavity. In order to analyse the feasibility of implementing a quantum memory in the atom-cavity system based on the EIT phenomenon, we investigated in detail which parameter configuration the memory efficiency is optimized considering the two different setups. Our results shows that for a asymmetric one-sided cavity, which is the experimental setup commonly used to observe the EIT effect, the memory efficiency value saturates at about 8 . 5 % . Meanwhile, for an one-sided cavity, we observe for a sufficiently high value of the coupling constant g, the efficiency has its maximum value increased considerably, close to 100 % . However, this experimental setup is not suitable to observe cavity-EIT in the transmission spectrum, being necessary another kind of experiment, such as measurements phase difference field that leaves the cavity induced by the control field. Considering this configuration we also showed the implementation of a quantum phase gate based on the same nonlinear effect, where the pulse probe can experience a phase shift on the order of π, due to the presence or absence of a control pulse. Supported by FAPESP (Proc. 2014/12740-1) and INCT-IQ.

  3. Molecular simulation and experimental study of substituted polyacetylenes: fractional free volume, cavity size distributions and diffusion coefficients.

    PubMed

    Wang, Xiao-Yan; Raharjo, Roy D; Lee, Hyuck J; Lu, Ying; Freeman, B D; Sanchez, I C

    2006-06-29

    Glassy, disubstituted acetylene-based polymers exhibit extremely high gas permeabilities and high vapor/gas selectivities, which is quite unusual for conventional glassy polymers such as polysulfone. Diffusion coefficients of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA) and poly[diphenylacetylene] (PDPA) were obtained using both molecular simulation and experimental techniques. PTMSDPA, a disubstituted glassy acetylene-based polymer, exhibits higher diffusivity than its desilylated analogue, PDPA. Simulation results are in good agreement with experimental data. Cavity size (free volume) distributions of both polymers are also obtained using an energetic-based algorithm (in't Veld et al., J. Phys. Chem. B 2000, 104, 12028) developed recently. Larger cavities in PTMSDPA contribute to its higher diffusivity, and higher permeability.

  4. Magnetic microtraps for cavity QED, Bose-Einstein condensates, and atom optics

    NASA Astrophysics Data System (ADS)

    Lev, Benjamin L.

    The system comprised of an atom strongly coupled to photons, known as cavity quantum electrodynamics (QED), provides a rich experimental setting for quantum information processing, both in the implementation of quantum logic gates and in the development of quantum networks. Moreover, studies of cavity QED will help elucidate the dynamics of continuously observed open quantum systems with quantum-limited feedback. To achieve these goals in cavity QED, a neutral atom must be tightly confined inside a high-finesse cavity with small mode volume for long periods of time. Microfabricated wires on a substrate---known as an atom chip---can create a sufficiently high-curvature magnetic potential to trap atoms in the Lamb-Dicke regime. We have recently integrated an optical fiber Fabry-Perot cavity with such a device. The microwires allow the on-chip collection and laser cooling of neutral atoms, and allow the magnetic waveguiding of these atoms to an Ioffe trap inside the cavity mode. Magnetically trapped intracavity atoms have been detected with this cavity QED system. A similar experiment employing microdisks and photonic bandgap cavities is nearing completion. With these more exotic cavities, a robust and scalable atom-cavity chip system will deeply probe the strong coupling regime of cavity QED with magnetically trapped atoms. Atom chips have found great success in producing and manipulating Bose-Einstein condensates and in creating novel atom optical elements. An on-chip BEC has been attained in a miniaturized system incorporating an atom chip designed for atom interferometry and for studies of Josephson effects of a BEC in a double-well potential. Using similar microfabrication techniques, we created and demonstrated a specular magnetic atom mirror formed from a standard computer hard drive. This device, in conjunction with micron-sized charged circular pads, can produce a 1-D ring trap which may prove useful for studying Tonks gases in a ring geometry and for

  5. An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

    NASA Astrophysics Data System (ADS)

    Uphoff, Manuel; Brekenfeld, Manuel; Rempe, Gerhard; Ritter, Stephan

    2016-03-01

    Quantum repeaters promise to enable quantum networks over global distances by circumventing the exponential decrease in success probability inherent in direct photon transmission. We propose a realistic, functionally integrated quantum-repeater implementation based on single atoms in optical cavities. Entanglement is directly generated between the single-atom quantum memory and a photon at telecom wavelength. The latter is collected with high efficiency and adjustable temporal and spectral properties into a spatially well-defined cavity mode. It is heralded by a near-infrared photon emitted from a second, orthogonal cavity. Entanglement between two remote quantum memories can be generated via an optical Bell-state measurement, while we propose entanglement swapping based on a highly efficient, cavity-assisted atom-atom gate. Our quantum-repeater scheme eliminates any requirement for wavelength conversion such that only a single system is needed at each node. We investigate a particular implementation with rubidium and realistic parameters for Fabry-Perot cavities based on hbox {CO}_2 laser-machined optical fibers. We show that the scheme enables the implementation of a rather simple quantum repeater that outperforms direct entanglement generation over large distances and does not require any improvements in technology beyond the state of the art.

  6. Off-Axis Cavity Ring Down Spectroscopy Based on a Continuous-Wave Optical Parametric Oscillator

    NASA Astrophysics Data System (ADS)

    Peltola, Jari; Siltanen, Mikael; Halonen, Lauri; Vainio, Markku

    2011-06-01

    Continuous-wave cavity ring down spectroscopy (cw-CRDS) is a sensitive absorption technique for trace gas analysis. Although it is highly sensitivity and relatively fast, ring down repetition rate and spectral resolution are limited by the cavity free spectral range (FSR). Normally, the injected beam is mode matched to the lowest transverse electro-magnetic mode (TEM00) of the cavity. Light is coupled into the cavity only when standing wave condition is fulfilled. Scanning of the laser without variation of the cavity length leads to transmission comb where recorded ring down times are separated in frequency by the FSR. Recently Romanini et. al. reported an off-axis (OA) CRDS spectrometer operating in the 766 nm region where the FSR of the cavity was reduced by N = 4 times from the original. In this re-entrant condition the cavity length is chosen to provide degeneracy of transverse modes. If the injection is adequately off-axis the beam returns to the starting point after N round trips. This divides the FSR to N group of degenerated modes which are equally frequency-spaced. We present an OA-CRDS spectrometer (N = 4) based on a continuous-wave optical parametric oscillator (cw-OPO) operating in the mid-infrared region (2.75 - 3.45 μm). The measurement of formaldehyde (H_2CO) using an OA-CRDS spectrometer will be presented. J. Courtois, A. K. Mohamed and D. Romanini Opt. Express 18, (5), 1 March 2010.

  7. Design and test of the microwave cavity in an optically-pumped Rubidium beam frequency standard

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Wang, Yan-Hui

    2015-01-01

    We are developing a compact rubidium atomic beam frequency standard with optical pumping and detection. The cavity for microwave interrogation is an important part of the clock. The cavity in our design is a Ramsey-type, E-bend one, which is the same as the conventional method in most cesium beam clocks. Requirements for the design are proposed based on the frequency shift associated with the cavity. The basic structure of the cavity is given by theoretical analysis and detailed dimensions are determined by means of electromagnetic field simulation with the help of commercial software. The cavity is manufactured and fabricated successfully. The preliminary test result of the cavity is given, which is in good agreement with the simulation. The resonant frequency is 6.835 GHz, equal to the clock transition frequency of 87Rb, and the loaded quality factor is 500. These values are adjustable with posts outside the cavity. Estimations on the Ramsey line width and several frequency shifts are made. Project supported by the National Natural Science Foundation of China (Grant No. 11174015).

  8. Towards Many-Body Quantum Engineering in a Near-Concentric Optical Cavity

    NASA Astrophysics Data System (ADS)

    Davis, Emily; Bentsen, Gregory; Schleier-Smith, Monika

    2016-05-01

    Light-mediated interactions between atoms coupled to an optical cavity offer a powerful approach to engineering Hamiltonians giving rise to many-body entanglement. The interactions are non-local, and both their strength and sign can be dynamically controlled. We present an experiment optimized for generating coherent and controllable light-mediated interactions by trapping atoms in the waist of a near-concentric cavity. The unique near-concentric geometry provides strong atom-light coupling and furthermore allows high spatial resolution for local addressing and imaging from the side of the cavity. The latter capability will enable entanglement of atomic sub-ensembles and detection of spatial correlations. We report here on the completed construction and characterization of the near-concentric cavity, as well as progress towards many-particle quantum control.

  9. Self-cavity lasing in optically pumped single crystals of p-sexiphenyl

    SciTech Connect

    Yanagi, Hisao Tamura, Kenji; Sasaki, Fumio

    2016-08-15

    Organic single-crystal self-cavities are prepared by solution growth of p-sexiphenyl (p-6P). Based on Fabry-Pérot feedback inside a quasi-lozenge-shaped platelet crystal, edge-emitting laser is obtained under optical pumping. The multimode lasing band appears at the 0-1 or 0-2 vibronic progressions depending on the excitation conditions which affect the self-absorption effect. Cavity-size dependence of amplified spontaneous emission (ASE) is investigated with laser-etched single crystals of p-6P. As the cavity length of square-shaped crystal is reduced from 100 to 10 μm, ASE threshold fluence is decreased probably due to size-dependent light confinement in the crystal cavity.

  10. Self-amplified lock of an ultra-narrow linewidth optical cavity.

    PubMed

    Izumi, Kiwamu; Sigg, Daniel; Barsotti, Lisa

    2014-09-15

    High finesse optical cavities are an essential tool in modern precision laser interferometry. The incident laser field is often controlled and stabilized with an active feedback system such that the field resonates in the cavity. The Pound-Drever-Hall reflection locking technique is a convenient way to derive a suitable error signal. However, it only gives a strong signal within the cavity linewidth. This poses a problem for locking an ultra-narrow linewidth cavity. We present a novel technique for acquiring lock by utilizing an additional weak control signal, but with a much larger capture range. We numerically show that this technique can be applied to the laser frequency stabilization system used in the Laser Interferometric Gravitational-wave Observatory (LIGO), which has a linewidth of 0.8 Hz. This new technique will allow us to robustly and repeatedly lock the LIGO laser frequency to the common mode of the interferometer.

  11. All-optical transistor based on a cavity optomechanical system with a Bose-Einstein condensate

    SciTech Connect

    Chen, Bin; Jiang, Cheng; Li, Jin-Jin; Zhu, Ka-Di

    2011-11-15

    We propose a scheme of an all-optical transistor based on a coupled Bose-Einstein condensate cavity system. The calculated results show that, in such an optomechanical system, the transmission of the probe beam is strongly dependent on the optical pump power. Therefore, the optical pump field can serve as a ''gate'' field of the transistor, effectively controlling the propagation of the probe field (the ''signal'' field). The scheme proposed here may have potential applications in optical communication and quantum information processing.

  12. Efficient phase noise suppression of an external-cavity diode-laser by optical filtering and resonant optical feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Miyakawa, S.; Kasai, K.; Okada-Shudo, Y.; Watanabe, M.

    2012-07-01

    We experimentally demonstrated that the excess phase noise of an external cavity diode laser (ECDL) can be efficiently suppressed by optical filtering and resonant optical feedback techniques. A suppression of more than 40 dB phase noise was obtained for the first time using these methods. It made that the phase noise of the ECDL reached shot noise level from 15 MHz. This opens a new way to reduce the phase noise of diode lasers.

  13. Coupling librational and translational motion of a levitated nanoparticle in an optical cavity

    NASA Astrophysics Data System (ADS)

    Liu, Shengyan; Li, Tongcang; Yin, Zhang-qi

    2017-06-01

    An optically levitated nonspherical nanoparticle can exhibit both librational and translational vibrations due to orientational and translational confinements of the optical tweezer, respectively. Usually, the frequency of its librational mode in a linearly-polarized optical tweezer is much larger than the frequency of its translational mode. Because of the frequency mismatch, the intrinsic coupling between librational and translational modes is very weak in vacuum. Here we propose a scheme to couple its librational and center-of-mass modes with an optical cavity mode. By adiabatically eliminating the cavity mode, the beam splitter Hamiltonian between librational and center-of-mass modes can be realized. We find that high-fidelity quantum state transfer between the librational and translational modes can be achieved with practical parameters. Our work may find applications in sympathetic cooling of multiple modes and quantum information processing.

  14. Variation of optical sideband intensity with current tuning in an extended cavity diode laser

    NASA Astrophysics Data System (ADS)

    Roach, Timothy; Ryor, Josh

    2010-03-01

    We have observed large, systematic changes in the intensity of optical sidebands of an extended cavity diode laser (ECDL) as the DC injection current is changed. These sidebands have applications for Raman spectroscopy and optical pumping (in our case, repumping of a laser cooling transition). The sidebands are produced by microwave modulation of the injection current (f ˜ 3GHz) and the optical intensity is about 2% of the total. Changing the DC current of the grating feedback ECDL produces optical frequency tuning in smooth stretches separated by mode hops several mA apart. Within each smooth-tuning cycle the intensity of the sidebands changes by a factor of 5 or more. We compare this behavior to a model of the competition between the laser chip and ECDL cavity modes.

  15. Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity

    DOE PAGES

    Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun

    2015-11-24

    We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrarymore » macropulse width and repetition rate.« less

  16. A 0.4-THz Second Harmonic Gyrotron with Quasi-Optical Confocal Cavity

    NASA Astrophysics Data System (ADS)

    Guan, Xiaotong; Fu, Wenjie; Yan, Yang

    2017-09-01

    Mode density is very relevant for harmonic gyrotron cavity. Theoretical investigations suggest that quasi-optical confocal waveguide performs low mode density and good mode-selective character. By selecting the appropriate mode and optimizing the cavity parameters, the quasi-optical confocal cavity is suitable for high-harmonic terahertz gyrotron without mode competition. In order to verify the theoretical analysis, a 0.4-THz second harmonic gyrotron has been designed and experimented. Driven by a 40-kV, 4.75-A electron beam and 7.51-T magnetic field, the gyrotron prototype could generate 6.44 kW of output power at 395.35 GHz, which corresponds to an electron efficiency of 3.4%. There is no mode competition between the second harmonic and fundamental observed in the experiments.

  17. Entanglement of movable mirror and cavity field enhanced by an optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Cai-yun, Zhang; Hu, Li; Gui-xia, Pan; Zong-qiang, Sheng

    2016-07-01

    A scheme to generate entanglement in a cavity optomechanical system filled with an optical parametric amplifier is proposed. With the help of the optical parametric amplifier, the stationary macroscopic entanglement between the movable mirror and the cavity field can be notably enhanced, and the entanglement increases when the parametric gain increases. Moreover, for a given parametric gain, the degree of entanglement of the cavity optomechanical system increases with increasing input laser power. Project supported by the National Natural Science Foundation of China (Grant No. 11247001), the Scientific Research Foundation of the Higher Education Institutions of Anhui Province, China (Grant No. KJ2012A083), and the Doctor (Master) Fund of Anhui University of Science and Technology, China.

  18. Optical response of a misaligned and suspended Fabry-Perot cavity

    SciTech Connect

    Cella, G.; Di Virgilio, A.; La Penna, P.; D'Auria, V.; Porzio, A.; Ricciardi, I.; Solimeno, S.

    2006-07-15

    The response to a probe laser beam of a suspended, misaligned, and detuned optical cavity is examined. A five degree of freedom dynamical model of the fluctuations of the longitudinal and transverse mirror coordinates is presented. Classical and quantum mechanical effects of radiation pressure are studied with the help of the optical stiffness coefficients and the signals provided by an FM sideband technique and a quadrant detector, for generic values of the product {tau} of the fluctuation frequency times the cavity round trip. A simplified version is presented for the case of small misalignments. Mechanical stability, mirror position entanglement, and ponderomotive squeezing are accommodated in this model. Numerical plots refer to cavities under test at the so-called Pisa LF facility. The presented model can describe radiation pressure effects recently appeared in the VIRGO antenna and give a framework for designing the next generation of gravitational wave antennas where such effects would be of critical relevance.

  19. Photoacoustic-guided convergence of light through optically diffusive media.

    PubMed

    Kong, Fanting; Silverman, Ronald H; Liu, Liping; Chitnis, Parag V; Lee, Kotik K; Chen, Y C

    2011-06-01

    We demonstrate that laser beams can be converged toward a light-absorbing target through optically diffusive media by using photoacoustic-guided interferometric focusing. The convergence of light is achieved by shaping the wavefront of the incident light with a deformable mirror to maximize the photoacoustic signal, which is proportional to the scattered light intensity at the light absorber.

  20. Photoacoustic-guided convergence of light through optically diffusive media

    PubMed Central

    Kong, Fanting; Silverman, Ronald H.; Liu, Liping; Chitnis, Parag V.; Lee, Kotik K.; Chen, Y. C.

    2012-01-01

    We demonstrate that laser beams can be converged toward a light-absorbing target through optically diffusive media by using photoacoustic-guided interferometric focusing. The convergence of light is achieved by shaping the wavefront of the incident light with a deformable mirror to maximize the photoacoustic signal, which is propor tional to the scattered light intensity at the light absorber. PMID:21633446

  1. Detecting quantum coherence of Bose gases in optical lattices by scattering light intensity in cavity.

    PubMed

    Zhou, Xiaoji; Xu, Xu; Yin, Lan; Liu, W M; Chen, Xuzong

    2010-07-19

    We propose a new method of detecting quantum coherence of a Bose gas trapped in a one-dimensional optical lattice by measuring the light intensity from Raman scattering in cavity. After pump and displacement process, the intensity or amplitude of scattering light is different for different quantum states of a Bose gas, such as superfluid and Mott-Insulator states. This method can also be useful to detect quantum states of atoms with two components in an optical lattice.

  2. Photonic crystal cavity on optical fiber facet for refractive index sensing.

    PubMed

    Wang, Bowen; Siahaan, Timothy; Dündar, Mehmet A; Nötzel, Richard; van der Hoek, Marinus J; He, Sailing; van der Heijden, Rob W

    2012-03-01

    Using a micromanipulation technique, a planar photonic crystal nanocavity made from a thin semiconductor membrane is released from the host semiconductor and attached to the end facet of a standard single-mode optical fiber. The cavity spectrum can be read out through the fiber by detecting the photoluminescence of embedded quantum dots. The modified fiber end serves as a fiber-optic refractive index sensor.

  3. Chiral optical local density of states in a spiral plasmonic cavity

    NASA Astrophysics Data System (ADS)

    Pham, Aline; Berthel, Martin; Jiang, Quanbo; Bellessa, Joel; Huant, Serge; Genet, Cyriaque; Drezet, Aurélien

    2016-11-01

    We discuss an alternate paradigm: the chiral electromagnetic local density of states (LDOS) in a spiral plasmonic nanostructure. In both classical and quantum regimes, we reveal using near-field scanning optical microscopy (NSOM) in combination with spin analysis that a spiral cavity possesses spin-dependent local optical modes. We expect this work to lead to promising directions for future quantum plasmonic device development, highlighting the potentials of chirality in quantum information processing.

  4. Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction

    NASA Astrophysics Data System (ADS)

    Wang, Lihong

    2014-03-01

    A decade of research has pushed photoacoustic computed tomography to the forefront of molecular-level imaging, notes SPIE Fellow Lihong Wang (Washington University, St. Louis) in his plenary talk, "Photoacoustic Tomography: Ultrasonically Beating Optical Diffusion and Diffraction." Modern optical microscopy has resolution and diffraction limitations. But noninvasive functional photoacoustic computed tomography has overcome this limit, offering deep penetration with optical contrast and ultrasonic resolution of 1 cm depth or more -- up to 7 cm of penetration in some cases, such as evaluating sentinel lymph nodes for breast cancer staging. This opens up applications in whole body imaging, brain function, oxygen saturation, label-free cell analysis, and noninvasive cancer biopsies.

  5. Arbitrary GRIN component fabrication in optically driven diffusive photopolymers.

    PubMed

    Urness, Adam C; Anderson, Ken; Ye, Chungfang; Wilson, William L; McLeod, Robert R

    2015-01-12

    We introduce a maskless lithography tool and optically-initiated diffusive photopolymer that enable arbitrary two-dimensional gradient index (GRIN) polymer lens profiles. The lithography tool uses a pulse-width modulated deformable mirror device (DMD) to control the 8-bit gray-scale intensity pattern on the material. The custom polymer responds with a self-developing refractive index profile that is non-linear with optical dose. We show that this nonlinear material response can be corrected with pre-compensation of the intensity pattern to yield high fidelity, optically induced index profiles. The process is demonstrated with quadratic, millimeter aperture GRIN lenses, Zernike polynomials and GRIN Fresnel lenses.

  6. Benchmark calculations of excess electrons in water cluster cavities: balancing the addition of atom-centered diffuse functions versus floating diffuse functions.

    PubMed

    Zhang, Changzhe; Bu, Yuxiang

    2016-09-14

    Diffuse functions have been proved to be especially crucial for the accurate characterization of excess electrons which are usually bound weakly in intermolecular zones far away from the nuclei. To examine the effects of diffuse functions on the nature of the cavity-shaped excess electrons in water cluster surroundings, both the HOMO and LUMO distributions, vertical detachment energies (VDEs) and visible absorption spectra of two selected (H2O)24(-) isomers are investigated in the present work. Two main types of diffuse functions are considered in calculations including the Pople-style atom-centered diffuse functions and the ghost-atom-based floating diffuse functions. It is found that augmentation of atom-centered diffuse functions contributes to a better description of the HOMO (corresponding to the VDE convergence), in agreement with previous studies, but also leads to unreasonable diffuse characters of the LUMO with significant red-shifts in the visible spectra, which is against the conventional point of view that the more the diffuse functions, the better the results. The issue of designing extra floating functions for excess electrons has also been systematically discussed, which indicates that the floating diffuse functions are necessary not only for reducing the computational cost but also for improving both the HOMO and LUMO accuracy. Thus, the basis sets with a combination of partial atom-centered diffuse functions and floating diffuse functions are recommended for a reliable description of the weakly bound electrons. This work presents an efficient way for characterizing the electronic properties of weakly bound electrons accurately by balancing the addition of atom-centered diffuse functions and floating diffuse functions and also by balancing the computational cost and accuracy of the calculated results, and thus is very useful in the relevant calculations of various solvated electron systems and weakly bound anionic systems.

  7. Diffusion tensor imaging of occult injury of optic radiation following optic neuritis in multiple sclerosis

    PubMed Central

    Chen, Jiafeng; Zhu, Lijun; Li, He; Lu, Ziwen; Chen, Xin; Fang, Shaokuan

    2016-01-01

    Multiple sclerosis (MS) is easily detected by routine magnetic resonance imaging (MRI). However, it is not possible to detect early or occult lesions in MS by routine MRI, and this may explain the inconsistency between the severity of the lesions found by MRI and the degree of clinical disability of patients with MS. The present study included 10 patients with relapsing-remitting MS and 10 healthy volunteers. Each patient underwent routine 3.0 T MRI, diffusion tensor imaging (DTI), and diffusion tensor tractography (DTT). Optic nerve and optic radiation were analyzed by DTI and DTT. The fractional anisotropy (FA), mean diffusivity (MD), λ//, and λ┴ values were measured. In the 10 patients with MS, 7 optic nerves were affected, and 13 optic nerves were not affected. Cranial MRI showed that optic nerve thickening and hyperintensity occurred in 2 patients with MS. In the directionally encoded color maps, a hypointensive green signal in the optic nerve was observed in 3 patients with MS. The FA values were significantly lower and the MD, λ//, and λ┴ values were significantly higher in the affected and unaffected optic nerves and optic radiations in patients with MS in comparison with controls (P<0.05). There were no significant differences in these values between the affected and unaffected optic nerves and optic radiation in patients with MS (P>0.05). Diffusion tensor imaging is sensitive in the detection of occult injury of the optic nerve and optic radiation following optic neuritis. Diffusion tensor imaging may be a useful tool for the early diagnosis, treatment and management of MS. PMID:27703508

  8. Development of a 4-mirror optical cavity for an inverse Compton scattering experiment in the STF

    NASA Astrophysics Data System (ADS)

    Shimizu, Hirotaka; Aryshev, Alexander; Higashi, Yasuo; Honda, Yosuke; Urakawa, Junji

    2014-05-01

    To obtain high-brightness quasi-monochromatic X-rays via inverse Compton scattering (ICS), an optical cavity for intensifying laser beams was designed and implemented in a new beam line at the KEK Superconducting RF Test Facility (STF) accelerator. The optical cavity adopts a planar configuration consisting of 4 mirrors. This confocal type resonator provides stable laser storage even with a long mirror distance, enabling head-on collision with the electron beams. To overcome the well-known astigmatism problems of the planar-type optical cavity, two forcibly bendable cylindrical mirrors were introduced instead of flat mirrors. With this new function for laser profile adjustment, an almost round laser profile at the waist point in the accelerator environment was successfully achieved. Estimated waist sizes were 43.7 μm for the horizontal and 50.8 μm for the vertical dimensions. The feedback control of this 4-mirror optical cavity worked with a stiff plate supporting all 4 mirrors. 1.7×103 finesse and 2.8-kW stored power for a 1-ms duration with 5 Hz were achieved.

  9. Homoclinic orbits and chaos in a second-harmonic generating optical cavity

    SciTech Connect

    Holm, D.; Kovacic, G., Timofeyev, I.

    1997-04-01

    We present two large families of Silnikov-type homoclinic orbits in a two mode-model that describes second-harmonic generation in a passive optical cavity. These families of homoclinic orbits give rise to chaotic dynamics in the model. 4 refs., 1 fig.

  10. Single orbital angular momentum mode emission from vertical cavity surface emitting laser by optical feedback

    NASA Astrophysics Data System (ADS)

    Toda, Y.; Moriya, H.; Shigematsu, K.; Yamane, K.; Morita, R.; Awaji, Y.

    2017-04-01

    Single angular momentum (OAM) mode emissions from a vertical cavity surface emitting laser (VCSEL) were demonstrated by an external optical feedback using computer generated holograms, which are optimized on the OAM modal gain of the free-running VCSEL. Side-mode suppression ratio of more than 23 dB was achieved for the OAM modes with l = +/-1.

  11. Note: A compact external-cavity diode laser, using feedback from an optical fiber.

    PubMed

    Potnis, S; Edge, G J A; Jackson, S; Verma, M; Vutha, A C

    2017-09-01

    We demonstrate a simple and compact external cavity diode laser (ECDL), where light reflected from the tip of an optical fiber provides feedback, and an interference filter provides frequency selection. The ECDL combines ease of construction with robust operation and exhibits a linewidth of 50 kHz.

  12. Note: A compact external-cavity diode laser, using feedback from an optical fiber

    NASA Astrophysics Data System (ADS)

    Potnis, S.; Edge, G. J. A.; Jackson, S.; Verma, M.; Vutha, A. C.

    2017-09-01

    We demonstrate a simple and compact external cavity diode laser (ECDL), where light reflected from the tip of an optical fiber provides feedback, and an interference filter provides frequency selection. The ECDL combines ease of construction with robust operation and exhibits a linewidth of 50 kHz.

  13. Operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser

    SciTech Connect

    Zhang Wei; Ackemann, Thorsten; McGinily, Stephen; Schmid, Marc; Riis, Erling; Ferguson, Allister I

    2006-10-10

    We report the operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser. The laser delivers 1 W at 855 nm and is pumped with a cost-effective fiber-coupled laser diode emitting at 806 nm. The laser modal gain is examined and ways of optimizing the system are investigated and discussed.

  14. Observation of motion-dependent nonlinear dispersion with narrow-linewidth atoms in an optical cavity.

    PubMed

    Westergaard, Philip G; Christensen, Bjarke T R; Tieri, David; Matin, Rastin; Cooper, John; Holland, Murray; Ye, Jun; Thomsen, Jan W

    2015-03-06

    As an alternative to state-of-the-art laser frequency stabilization using ultrastable cavities, it has been proposed to exploit the nonlinear effects from coupling of atoms with a narrow transition to an optical cavity. Here, we have constructed such a system and observed nonlinear phase shifts of a narrow optical line by a strong coupling of a sample of strontium-88 atoms to an optical cavity. The sample temperature of a few mK provides a domain where the Doppler energy scale is several orders of magnitude larger than the narrow linewidth of the optical transition. This makes the system sensitive to velocity dependent multiphoton scattering events (Dopplerons) that affect the cavity field transmission and phase. By varying the number of atoms and the intracavity power, we systematically study this nonlinear phase signature which displays roughly the same features as for much lower temperature samples. This demonstration in a relatively simple system opens new possibilities for alternative routes to laser stabilization at the sub-100 mHz level and superradiant laser sources involving narrow-line atoms. The understanding of relevant motional effects obtained here has direct implications for other atomic clocks when used in relation to ultranarrow clock transitions.

  15. Three-dimensional spatial diffusion in optical molasses

    NASA Astrophysics Data System (ADS)

    Hodapp, T. W.; Gerz, C.; Furtlehner, C.; Westbrook, C. I.; Phillips, W. D.; Dalibard, J.

    1995-02-01

    We have studied the expansion of a small cloud of85Rb atoms in three-dimensional optical molasses (lin ⊥ lin and σ+ - σ- configurations) and observed diffusive motion. We determined the spatial-diffusion coefficients for various laser intensities and detunings, and compared them (in the case of lin ⊥ lin molasses) to values calculated from friction and momentum-diffusion coefficients of a one-dimensional (1D) theory of laser cooling. The predicted variations of the spatial-diffusion coefficient with laser intensity and detuning are in good qualitative agreement with the experimental data. We found that the minimal value observed experimentally, ≈ 6 × 10-4 cm2/s, lies within a factor of 3 of the 1D theoretical minimum, ≈, 26ħ/ M, where M is the atomic mass.

  16. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

    PubMed Central

    van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F.; Kilpatrick, Trevor J.

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = −0.428, p = 0.009; MD: R = −0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage. PMID:27555964

  17. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis.

    PubMed

    Kolbe, Scott C; van der Walt, Anneke; Butzkueven, Helmut; Klistorner, Alexander; Egan, Gary F; Kilpatrick, Trevor J

    2016-01-01

    Previous studies have reported diffusion tensor imaging (DTI) changes within the optic radiations of patients after optic neuritis (ON). We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1). We measured DTI parameters [fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD)] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of -2.6% per annum (control = -0.51%; p = 0.006). Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R = 0.450, p = 0.006; RD: R = -0.428, p = 0.009; MD: R = -0.365, p = 0.029). In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R = 0.489, p = 0.039). In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

  18. Measurements of Extinction by Aerosol Particles Using Cavity Ring-Down Spectroscopy and Optical Feedback Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mellon, Daniel; Kim, Jin; Orr-Ewing, Andrew J.

    2009-06-01

    Cavity ring-down spectroscopy and optical feedback cavity ring-down spectroscopy using continuous-wave distributed-feedback diode lasers around 1.6 μm and 400 nm have been used to measure the extinction of light by samples of monodisperse spherical aerosol particles < 1 μm in diameter. A statistical model is proposed to describe the linear relationship between the extinction coefficient (α) and its variance Var(α). Application of this model to experimental measurements of Var(α) for a range of (α) values typically below 2 × 10^{-6} cm^{-1} allows extinction cross sections for the aerosol particles to be obtained without need for knowledge of the particle number density. Samples of polystyrene spheres with diameters of 400 nm, 500 nm, 600 nm, 700 nm and 900 nm were used to test the model, by comparing extinction cross sections determined from the experiment with the predictions of Mie theory calculations. The fitting method used to extract decay constants, aggregation of particles and their cloud-like motion can all provide extra contributions to Var(α) and are understood with the aid of computer simulations. T.J.A. Butler, D. Mellon, J. Kim, J. Litman and A.J. Orr-Ewing J. Chem. Phys. A in press (2009)

  19. Quantum phase gate based on electromagnetically induced transparency in optical cavities

    NASA Astrophysics Data System (ADS)

    Borges, Halyne S.; Villas-Bôas, Celso J.

    2016-11-01

    We theoretically investigate the implementation of a quantum controlled-phase gate in a system constituted by a single atom inside an optical cavity, based on the electromagnetically induced transparency effect. First we show that a probe pulse can experience a π phase shift due to the presence or absence of a classical control field. Considering the interplay of the cavity-EIT effect and the quantum memory process, we demonstrated a controlled-phase gate between two single photons. To this end, first one needs to store a (control) photon in the ground atomic states. In the following, a second (target) photon must impinge on the atom-cavity system. Depending on the atomic state, this second photon will be either transmitted or reflected, acquiring different phase shifts. This protocol can then be easily extended to multiphoton systems, i.e., keeping the control photon stored, it may induce phase shifts in several single photons, thus enabling the generation of multipartite entangled states. We explore the relevant parameter space in the atom-cavity system that allows the implementation of quantum controlled-phase gates using the recent technologies. In particular, we have found a lower bound for the cooperativity of the atom-cavity system which enables the implementation of phase shift on single photons. The induced shift on the phase of a photonic qubit and the controlled-phase gate between single photons, combined with optical devices, enable one to perform universal quantum computation.

  20. Automated optical inspection and image analysis of superconducting radio-frequency cavities

    NASA Astrophysics Data System (ADS)

    Wenskat, M.

    2017-05-01

    The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. For an investigation of this inner surface of more than 100 cavities within the cavity fabrication for the European XFEL and the ILC HiGrade Research Project, an optical inspection robot OBACHT was constructed. To analyze up to 2325 images per cavity, an image processing and analysis code was developed and new variables to describe the cavity surface were obtained. The accuracy of this code is up to 97 % and the positive predictive value (PPV) 99 % within the resolution of 15.63 μm. The optical obtained surface roughness is in agreement with standard profilometric methods. The image analysis algorithm identified and quantified vendor specific fabrication properties as the electron beam welding speed and the different surface roughness due to the different chemical treatments. In addition, a correlation of ρ = -0.93 with a significance of 6 σ between an obtained surface variable and the maximal accelerating field was found.

  1. Water-walled microfluidics for high-optical finesse cavities

    NASA Astrophysics Data System (ADS)

    Maayani, Shai; Martin, Leopoldo L.; Carmon, Tal

    2016-01-01

    In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation. More than enabling a nearly-perfect optical overlap with water, atomic-level surface smoothness that minimizes scattering loss, and ~99% coupling efficiency from a standard fibre. Surface tension in our droplet is 8,000 times stronger than gravity, suggesting a new class of devices with water-made walls, for new fields of study including opto-capillaries.

  2. Water-walled microfluidics for high-optical finesse cavities.

    PubMed

    Maayani, Shai; Martin, Leopoldo L; Carmon, Tal

    2016-01-22

    In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation. More than enabling a nearly-perfect optical overlap with water, atomic-level surface smoothness that minimizes scattering loss, and ∼99% coupling efficiency from a standard fibre. Surface tension in our droplet is 8,000 times stronger than gravity, suggesting a new class of devices with water-made walls, for new fields of study including opto-capillaries.

  3. Water-walled microfluidics for high-optical finesse cavities

    PubMed Central

    Maayani, Shai; Martin, Leopoldo L.; Carmon, Tal

    2016-01-01

    In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation. More than enabling a nearly-perfect optical overlap with water, atomic-level surface smoothness that minimizes scattering loss, and ∼99% coupling efficiency from a standard fibre. Surface tension in our droplet is 8,000 times stronger than gravity, suggesting a new class of devices with water-made walls, for new fields of study including opto-capillaries. PMID:26794271

  4. Cavity Opto-Mechanics using an Optically Levitated Nanosphere

    DTIC Science & Technology

    2010-01-19

    Phys Rev Lett, 100:033602. 21. Yonezawa H, Braunstein SL, Furusawa A (2007) Experimental demonstration of quantum teleportation of broadband squeezing...Kimbleb,1, and P. Zollerb,e aInstitute for Quantum Information and Center for the Physics of Information, California Institute of Technology, Pasadena...Pasadena, CA 91125; and eInstitute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria

  5. Fabrication of optical cavities with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jintian; Song, Jiangxin; Tang, Jialei; Fang, Wei; Sugioka, Koji; Cheng, Ya

    2014-03-01

    We report on fabrication of three-dimensional (3D) high-quality (Q) whispering-gallery-mode microcavities by femtosecond laser micromachining. The main fabrication procedures include the formation of on-chip freestanding microdisk through selective material removal by femtosecond laser pulses, followed by surface smoothing processes (CO2 laser reflow for amorphous glass and focused ion beam (FIB) sidewall milling for crystalline materials) to improve the Q factors. Fused silica microcavities with 3D geometries are demonstrated with Q factors exceeding 106. A microcavity laser based on Nd:glass has been fabricated, showing a threshold as low as 69μW via free space continuous-wave optical excitation at the room temperature. CaF2 crystalline microcavities with Q factor of ~4.2×104 have also been demonstrated. This technique allows us to fabricate 3D high-Q microcavities in various transparent materials such as glass and crystals, which will benefit a broad spectrum of applications such as nonlinear optics, quantum optics, and bio-sensing.

  6. Constructions of secure entanglement channels assisted by quantum dots inside single-sided optical cavities

    NASA Astrophysics Data System (ADS)

    Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Choi, Seong-Gon; Hong, Jong-Phil

    2017-08-01

    We propose quantum information processing schemes to generate and swap entangled states based on the interactions between flying photons and quantum dots (QDs) confined within optical cavities for quantum communication. To produce and distribute entangled states (Bell and Greenberger-Horne-Zeilinger [GHZ] states) between the photonic qubits of flying photons of consumers (Alice and Bob) and electron-spin qubits of a provider (trust center, or TC), the TC employs the interactions of the QD-cavity system, which is composed of a charged QD (negatively charged exciton) inside a single-sided cavity. Subsequently, the TC constructs an entanglement channel (Bell state and 4-qubit GHZ state) to link one consumer with another through entanglement swapping, which can be realized to exploit a probe photon with interactions of the QD-cavity systems and single-qubit measurements without Bell state measurement, for quantum communication between consumers. Consequently, the TC, which has quantum nodes (QD-cavity systems), can accomplish constructing the entanglement channel (authenticated channel) between two separated consumers from the distributions of entangled states and entanglement swapping. Furthermore, our schemes using QD-cavity systems, which are feasible with a certain probability of success and high fidelity, can be experimentally implemented with technology currently in use.

  7. Resonance-free optical response of a vertical cavity transistor laser

    NASA Astrophysics Data System (ADS)

    Feng, M.; Wu, Cheng-Han; Wu, M. K.; Wu, Chao-Hsin; Holonyak, N.

    2017-09-01

    Optical resonance in a semiconductor laser is a major limitation in high speed data communications, resulting in bit error rate degradation and requiring additional power consuming error-correction circuits to counter these effects. In this work, we report the microwave bandwidth measurement of a vertical cavity transistor laser with an oxide-confined aperture of 4.7 × 5.4 μm2 and demonstrate a 3 dB bandwidth of 11 GHz resonance-free optical response via base-current or collector-voltage modulation. The emission spectra exhibit single-mode operation around 970 nm with a narrow linewidth of Δλ ˜ 0.23 Å (cavity Q of 42 216). The resonance-free optical response is explained by the absence of carrier "accumulating" due to the fast base electron-hole recombination lifetimes and a gradient in the minority carrier charge in the transistor active mode.

  8. Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing

    PubMed Central

    Wang, Weiqiang; Chu, Sai T.; Little, Brent E.; Pasquazi, Alessia; Wang, Yishan; Wang, Leiran; Zhang, Wenfu; Wang, Lei; Hu, Xiaohong; Wang, Guoxi; Hu, Hui; Su, Yulong; Li, Feitao; Liu, Yuanshan; Zhao, Wei

    2016-01-01

    In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness. PMID:27338250

  9. Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing.

    PubMed

    Wang, Weiqiang; Chu, Sai T; Little, Brent E; Pasquazi, Alessia; Wang, Yishan; Wang, Leiran; Zhang, Wenfu; Wang, Lei; Hu, Xiaohong; Wang, Guoxi; Hu, Hui; Su, Yulong; Li, Feitao; Liu, Yuanshan; Zhao, Wei

    2016-06-24

    In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness.

  10. Ultra-small Fabry-Perot cavities in tapered optical fibers

    NASA Astrophysics Data System (ADS)

    Warren-Smith, Stephen C.; André, Ricardo M.; Dellith, Jan; Bartelt, Hartmut

    2016-11-01

    The small dimensions of optical fiber sensors are of interest to biological applications, given the ability to penetrate relatively inaccessible regions. However, conventional optical fibers are larger than biological material such as cells, and thus there is a need for further miniaturization. Here we present the fabrication of ultra-small Fabry-Perot cavities written into optical micro-fibers using focused ion beam (FIB) milling. We have fabricated cavities as small as 2.8 μm and demonstrated their use for measuring refractive index. In order to achieve sensitive measurements we interrogate at visible wavelengths, thereby reducing the free spectral range of the interferometer (relative to infra-red interrogation), increasing the number of interference fringes, and allowing for the implementation of the Fourier shift method.

  11. Computational model and simulation for the whispering gallery modes inside micro-optical cavity

    NASA Astrophysics Data System (ADS)

    Ali, Amir R.; Erian, Abanoub M.; Shokry, Kirelloss

    2017-05-01

    A computational model for the whispering gallery modes inside a microsphere resonator is presented. In the archetypical microsphere resonator sensor, a tunable laser light beam is injected into an optical fiber and coupled with the resonator's cavity. The resonant optical coupling is achieved by bringing the fiber in the vicinity of the cavity's evanescent field. The transmission spectrum is then observed to detect the WGM shifts. In this paper, two-dimensional models of a single laser source put near the equator of a microsphere are simulated using COMSOL Multi-physics 5.1 electromagnetic waves, beam envelopes library. Afterwards, a three-dimensional model of two laser sources put near the horizontal and vertical equators of a microsphere is computed. The transmission spectrum of both simulations was taken and cross correlation was performed on them. Results show a big similarity between both simulations and could bring a breakthrough in the area of optical sensors.

  12. Size-dependent waveguide dispersion in nanowire optical cavities: slowed light and dispersionless guiding.

    PubMed

    van Vugt, Lambert K; Zhang, Bin; Piccione, Brian; Spector, Arthur A; Agarwal, Ritesh

    2009-04-01

    Fundamental understanding of the size dependence of nanoscale optical confinement in semiconductor nanowire waveguides, as expressed by changes in the dispersion of light, is crucial for the optimal design of nanophotonic devices. Measurements of the dispersion are particularly challenging for nanoscale cavities due to difficulties associated with the in- and out-coupling of light resulting from diffraction effects. We report the strong size dependence of optical dispersion and associated group velocities in subwavelength width ZnSe nanowire waveguide cavities, using a technique based on Fabry-Perot resonator modes as probes over a wide energy range. Furthermore, we observed subwavelength (lambda/9) dispersionless waveguiding and significant slowing of the propagating light by 90% (c/8). These results, in addition to providing insights into nanoscale optical transport, will facilitate the rational design of nanowire photonic devices with tailored dispersion and group velocities.

  13. Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing

    NASA Astrophysics Data System (ADS)

    Wang, Weiqiang; Chu, Sai T.; Little, Brent E.; Pasquazi, Alessia; Wang, Yishan; Wang, Leiran; Zhang, Wenfu; Wang, Lei; Hu, Xiaohong; Wang, Guoxi; Hu, Hui; Su, Yulong; Li, Feitao; Liu, Yuanshan; Zhao, Wei

    2016-06-01

    In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness.

  14. Realizing mode conversion and optical diode effect by coupling photonic crystal waveguides with cavity

    NASA Astrophysics Data System (ADS)

    Ye, Han; Zhang, Jin-Qian-Nan; Yu, Zhong-Yuan; Wang, Dong-Lin; Chen, Zhi-Hui

    2015-09-01

    We propose a novel two-dimensional photonic crystal structure consisting of two line defect waveguides and a cavity to realize mode conversion based on the coupling effect. The W1/cavity/W2 structure breaks the spatial symmetry and successfully converts the even (odd) mode to the odd (even) mode in the W2 waveguide during the forward (backward) transmission. When considering the incidence of only the even mode, the optical diode effect emerges and achieves approximate 35 dB unidirectionality at the resonant frequency. Moreover, owing to the narrow bandpass feature and the flexibility of the tuning cavity, utilization of the proposed structure as a wavelength filter is demonstrated in a device with a Y-branch splitter. Here, we provide a heuristic design for a mode converter, optical diode, and wavelength filter derived from the coupling effect between a cavity and adjacent waveguides, and expect that the proposed structure can be applied as a building block in future all-optical integrated circuits. Project supported by the National Natural Science Foundation of China (Grant Nos. 61372037 and 61307069), Beijing Excellent Ph. D. Thesis Guidance Foundation, China (Grant No. 20131001301), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2013021017-3).

  15. A simple-versatile approach to achieve all-Si-based optical micro-cavities

    NASA Astrophysics Data System (ADS)

    Gallo, I. B.; Zanatta, A. R.

    2013-02-01

    At present, solid thin films are recognized by their well established and mature processing technology that is able to produce components which, depending on their main characteristics, can perform either passive or active functions. Additionally, Si-based materials in the form of thin films perfectly match the concept of miniaturized and low-consumption devices—as required in various modern technological applications. Part of these aspects was considered in the present work that was concerned with the study of optical micro-cavities entirely based on silicon and silicon nitride thin films. The structures were prepared by the sputtering deposition method which, due to the adopted conditions (atmosphere and deposition rate) and arrangement of layers, provided cavities operating either in the visible (at ˜670 nm) or in the near-infrared (at ˜1560 nm) wavelength ranges. The main differential of the work relies on the construction of optical micro-cavities with a reduced number of periods whose main properties can be changed by thermal annealing treatments. The work also discusses the angle-dependent behavior of the optical transmission profiles as well as the use of the comsol software package to simulate the micro-cavities.

  16. Optical modes within III-nitride multiple quantum well microdisk cavities

    NASA Astrophysics Data System (ADS)

    Mair, R. A.; Zeng, K. C.; Lin, J. Y.; Jiang, H. X.; Zhang, B.; Dai, L.; Botchkarev, A.; Kim, W.; Morkoç, H.; Khan, M. A.

    1998-03-01

    Optical resonance modes have been observed in optically pumped microdisk cavities fabricated from 50 Å/50 Å GaN/AlxGa1-xN(x˜0.07) and 45 Å/45 Å InxGa1-xN/GaN(x˜0.15) multiple quantum well structures. Microdisks, approximately 9 μm in diameter and regularly spaced every 50 μm, were formed by an ion beam etch process. Individual disks were pumped at 300 and 10 K with 290 nm laser pulses focused to a spot size much smaller than the disk diameter. Optical modes corresponding to (i) the radial mode type with a spacing of 49-51 meV (both TE and TM) and (ii) the Whispering Gallery mode with a spacing of 15-16 meV were observed in the GaN microdisk cavities. The spacings of these modes are consistent with those expected for modes within a resonant cavity of cylindrical symmetry, refractive index, and dimensions of the microdisks under investigation. The GaN-based microdisk cavity is compared with its GaAs counterpart and implications regarding future GaN-based microdisk lasers are discussed.

  17. Towards diffuse optical tomography of arbitrarily heterogeneous turbid medium using GPU-accelerated Monte-Carlo forward calculation

    NASA Astrophysics Data System (ADS)

    Yi, Xi; Chen, Weiting; Wu, Linhui; Zhang, Wei; Li, Jiao; Wang, Xin; Zhang, Limin; Zhao, Huijuan; Gao, Feng

    2013-03-01

    At present, the most widely accepted forward model in diffuse optical tomography (DOT) is the diffusion equation, which is derived from the radiative transfer equation by employing the P1 approximation. However, due to its validity restricted to highly scattering regions, this model has several limitations for the whole-body imaging of small-animals, where some cavity and low scattering areas exist. To overcome the difficulty, we presented a Graphic-Processing- Unit(GPU) implementation of Monte-Carlo (MC) modeling for photon migration in arbitrarily heterogeneous turbid medium, and, based on this GPU-accelerated MC forward calculation, developed a fast, universal DOT image reconstruction algorithm. We experimentally validated the proposed method using a continuous-wave DOT system in the photon-counting mode and a cylindrical phantom with a cavity inclusion.

  18. Nanofiber Fabry-Perot microresonator for nonlinear optics and cavity quantum electrodynamics.

    PubMed

    Wuttke, C; Becker, M; Brückner, S; Rothhardt, M; Rauschenbeutel, A

    2012-06-01

    We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and cavity quantum electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications.

  19. Vertical-cavity surface-emitting lasers for flip-chip packaged vertical optical interconnects

    NASA Astrophysics Data System (ADS)

    O'Keefe, Sean S.; Schaff, William J.; Eastman, Lester F.

    1994-06-01

    Vertical cavity surface emitting lasers (VCSELs) have been fabricated and studied as the optical sources in a vertical optical interconnect application. The VCSELs are to replace LEDs that are currently used in a proof-of-concept demonstration. The advantages of VCSELs ares better power efficiency as sources, higher optical powers, focused beam output, monochromatic operation, and higher modulation bandwidth. The VCSELs used in this project are the first to implement continuously sinusoidally graded interface mirrors grown by molecular beam epitaxy. material parameters, device results, and interconnect implications are presented.

  20. 1300 nm optically pumped quantum dot spin vertical external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Alharthi, S. S.; Orchard, J.; Clarke, E.; Henning, I. D.; Adams, M. J.

    2015-10-01

    We report a room temperature optically pumped Quantum Dot-based Spin-Vertical-External-Cavity Surface-Emitting laser (QD Spin-VECSEL) operating at the telecom wavelength of 1.3 μm. The active medium was composed of 5 × 3 QD layers; each threefold group was positioned at an antinode of the standing wave of the optical field. Circularly polarized lasing in the QD-VECSEL under Continuous-Wave optical pumping has been realized with a threshold pump power of 11 mW. We further demonstrate at room temperature control of the QD-VECSEL output polarization ellipticity via the pump polarization.

  1. Overview of diffuse optical tomography and its clinical applications.

    PubMed

    Hoshi, Yoko; Yamada, Yukio

    2016-09-01

    Near-infrared diffuse optical tomography (DOT), one of the most sophisticated optical imaging techniques for observations through biological tissue, allows 3-D quantitative imaging of optical properties, which include functional and anatomical information. With DOT, it is expected to be possible to overcome the limitations of conventional near-infrared spectroscopy (NIRS) as well as offering the potential for diagnostic optical imaging. However, DOT has been under development for more than 30 years, and the difficulties in development are attributed to the fact that light is strongly scattered and that diffusive photons are used for the image reconstruction. The DOT algorithm is based on the techniques of inverse problems. The radiative transfer equation accurately describes photon propagation in biological tissue, while, because of its high computation load, the diffusion equation (DE) is often used as the forward model. However, the DE is invalid in low-scattering and/or highly absorbing regions and in the vicinity of light sources. The inverse problem is inherently ill-posed and highly undetermined. Here, we first summarize NIRS and then describe various approaches in the efforts to develop accurate and efficient DOT algorithms and present some examples of clinical applications. Finally, we discuss the future prospects of DOT.

  2. Overview of diffuse optical tomography and its clinical applications

    NASA Astrophysics Data System (ADS)

    Hoshi, Yoko; Yamada, Yukio

    2016-09-01

    Near-infrared diffuse optical tomography (DOT), one of the most sophisticated optical imaging techniques for observations through biological tissue, allows 3-D quantitative imaging of optical properties, which include functional and anatomical information. With DOT, it is expected to be possible to overcome the limitations of conventional near-infrared spectroscopy (NIRS) as well as offering the potential for diagnostic optical imaging. However, DOT has been under development for more than 30 years, and the difficulties in development are attributed to the fact that light is strongly scattered and that diffusive photons are used for the image reconstruction. The DOT algorithm is based on the techniques of inverse problems. The radiative transfer equation accurately describes photon propagation in biological tissue, while, because of its high computation load, the diffusion equation (DE) is often used as the forward model. However, the DE is invalid in low-scattering and/or highly absorbing regions and in the vicinity of light sources. The inverse problem is inherently ill-posed and highly undetermined. Here, we first summarize NIRS and then describe various approaches in the efforts to develop accurate and efficient DOT algorithms and present some examples of clinical applications. Finally, we discuss the future prospects of DOT.

  3. Diffusion model of the optical absorbance of whole blood.

    PubMed

    Steinke, J M; Shepherd, A P

    1988-06-01

    Photon-diffusion theory has had limited success in modeling the optical transmittance of whole blood. Therefore we have developed a new photon-diffusion model of the optical absorbance of blood. The model has benefited from experiments designed to test its fundamental assumptions, and it has been compared extensively with transmittance data from whole blood. The model is consistent with both experimental and theoretical notions. Furthermore, when all parameters associated with a given optical geometry are known, the model needs no variational parameters to predict the absolute transmittance of whole blood. However, even if the exact value of the incident light intensity is unknown (which is the case in many situations), only a single additive constant is required to scale experiment to theory. Finally, the model is shown to be useful for simulating scattering effects and for delineating the relative contributions of the diffuse transmittance and the collimated transmittance to the total optical density of whole blood. Applications of the model include oximetry and measurements of the arteriovenous oxygen difference in whole, undiluted blood.

  4. All-optical logic gates in plasmonic metal-insulator-metal nanowaveguide with slot cavity resonator

    NASA Astrophysics Data System (ADS)

    Dolatabady, Alireza; Granpayeh, Nosrat

    2017-04-01

    We demonstrate the compact all-optical logic XOR and OR gates in subwavelength plasmonic metal-insulator-metal waveguides with slot cavity resonators, especially for telecommunication wavelengths, with an extinction ratio of 25 dB, which can provide nanoscale logic integrated circuits. The gates behavior is based on suppression or enhancement of resonant modes in a slot cavity resonator induced by a change in position of input ports. The performance of the gates is discussed analytically and verified by the numerical method of finite-difference time-domain (FDTD).

  5. Intermodal beat length measurement with Fabry-Perot optical fiber cavities.

    PubMed

    Vaziri, M; Chen, C L

    1997-05-20

    We present a new technique for measuring the intermodal beat length of a two-mode optical fiber. We formed a Fabry-Perot fiber cavity by depositing reflective mirrors on the fiber tips. As the fiber is stretched, two series of resonance peaks are observed. One series is due to the resonance of LP(01 q) modes and the other is due to the LP(11 q) modes. From the separation of resonance peaks as a function of cavity length, we deduce the intermodal beat length of the fiber. The measurement principle and the experimental confirmation are discussed.

  6. Organic Fabry-Perot micro-cavity for electro-optic sampling by amplitude modulation

    NASA Astrophysics Data System (ADS)

    Gaborit, G.; Martin, G.; Duvillaret, L.; Coutaz, J.-L.; Nguyen, C.; Hierle, R.; Zyss, J.

    2006-02-01

    We present herein a original concept of electro-optic (EO) probe for high frequency electric field measurements. This sensors is based on a thin organic layer of DR1-PMMA embedded in a high finesse Fabry-Perot cavity. The optimal orientation of DRl molecules, parallel to the face of the micro-cavity, has been obtained thanks to a lateral poling method. A r 33 of 2.5 pm/V has been reached for a 16 μm thick polymer layer. The final probe exhibits high sensitivity of 2V.cm -1.Hz -1/2.

  7. Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser.

    PubMed

    Wu, Jia-Gui; Xia, Guang-Qiong; Tang, Xi; Lin, Xiao-Dong; Deng, Tao; Fan, Li; Wu, Zheng-Mao

    2010-03-29

    The time delay (TD) signature concealment of optical feedback induced chaos in an external cavity semiconductor laser is experimentally demonstrated. Both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current. The optimum parameter scope of the TD signature concealment is also specified. Furthermore, the approximately periodic evolution relation between TD signature and external cavity length is observed and indicates that the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression.

  8. Optical strain sensor based on FPI micro-cavities produced by the fiber fuse effect

    NASA Astrophysics Data System (ADS)

    Domingues, M. Fátima; Antunes, Paulo; Alberto, Nélia; Frias, Rita; Ferreira, Rute A. S.; André, Paulo

    2014-05-01

    In this work we present a cost effective strain sensor based on micro-cavities produced through the re-use of optical fibers destroyed by the catastrophic fuse effect. The strain sensor estimated sensitivity is 2.22 +/-0.08 pm/μƐ. After the fuse effect, the damaged fiber becomes useless and, consequently, it is an economical solution for sensing proposes, when compared with the cavities produced using other complex methods. Also, the low thermal sensitivity is of great interest in several practical applications, allowing eluding cross-sensitivity with less instrumentation, and consequently less cost.

  9. Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter

    SciTech Connect

    Dantan, A.; Albert, M.; Marler, J. P.; Herskind, P. F.; Drewsen, M.

    2009-10-15

    We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation and storage of single-photon qubits encoded in different transverse modes.

  10. Electro-optic harmonic conversion to switch a laser beam out of a cavity

    DOEpatents

    Haas, Roger A.; Henesian, Mark A.

    1987-01-01

    The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

  11. Optical Tracking of Anomalous Diffusion Kinetics in Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Foreman, Matthew R.; Vollmer, Frank

    2015-03-01

    In this Letter we propose the use of whispering gallery mode resonance tracking as a label-free optical means to monitor diffusion kinetics in glassy polymer microspheres. Approximate solutions to the governing diffusion equations are derived for the case of slow relaxation and small Stefan number. Transduction of physical changes in the polymer, including formation of a rubbery layer, swelling, and dissolution, into detectable resonance shifts are described using a perturbative approach. Concrete examples of poly(methyl methacrylate) and polystyrene spheres in water are considered.

  12. Fiber-coupled nanophotonic devices for nonlinear optics and cavity QED

    NASA Astrophysics Data System (ADS)

    Barclay, Paul Edward

    2007-10-01

    The sub-wavelength optical confinement and low optical loss of nanophotonic devices dramatically enhances the interaction between light and matter within these structures. When nanophotonic devices are combined with an efficient optical coupling channel, nonlinear optical behavior can be observed at low power levels in weakly-nonlinear materials. In a similar vein, when resonant atomic systems interact with nanophotonic devices, atom-photon coupling effects can be observed at a single quanta level. Crucially, the chip based nature of nanophotonics provides a scalable platform from which to study these effects. This thesis addresses the use of nanophotonic devices in nonlinear and quantum optics, including device design, optical coupling, fabrication and testing, modeling, and integration with more complex systems. We present a fiber taper coupling technique that allows efficient power transfer from an optical fiber into a photonic crystal waveguide. Greater than 97% power transfer into a silicon photonic crystal waveguide is demonstrated. This optical channel is then connected to a high-Q (> 40,000), ultra-small mode volume (V < (lambda/n)3) photonic crystal cavity, into which we couple > 44% of the photons input to a fiber. This permits the observation of optical bistability in silicon for sub-mW input powers at telecommunication wavelengths. To port this technology to cavity QED experiments at near-visible wavelengths, we also study silicon nitride microdisk cavities at wavelengths near 852 nm, and observe resonances with Q > 3 million and V < 15 (lambda/n)3). This Q/V ratio is sufficiently high to reach the strong coupling regime with cesium atoms. We then permanently align and mount a fiber taper within the near-field an array of microdisks, and integrate this device with an atom chip, creating an "atom-cavity chip" which can magnetically trap laser cooled atoms above the microcavity. Calculations of the microcavity single atom sensitivity as a function of Q

  13. Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime.

    PubMed

    Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V

    2012-06-01

    Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.

  14. Energy-efficient utilization of bipolar optical forces in nano-optomechanical cavities.

    PubMed

    Tian, Feng; Zhou, Guangya; Du, Yu; Chau, Fook Siong; Deng, Jie; Tang, Xiaosong; Akkipeddi, Ramam

    2013-07-29

    Nanoscale all-optical circuits driven by optical forces have broad applications in future communication, computation, and sensing systems. Because human society faces huge challenges of energy saving and emission reduction, it is very important to develop energy-efficient nano-optomechanical devices. Due to their high quality (Q) factors, resonance modes of cavities are capable of generating much larger forces than waveguide modes. Here we experimentally demonstrate the use of resonance modes of double-coupled one-dimensional photonic crystal cavities to generate bipolar optical forces. Attractive and repulsive forces of -6.2 nN and 1.9 nN were obtained with respective launching powers of 0.81 mW and 0.87 mW in the waveguide just before cavities. Supported by flexible nanosprings (spring constant 0.166 N/m), one cavity is pulled to (pushed away from) the other cavity by 37.1 nm (11.4 nm). The shifts of the selected resonance modes of the device are mechanically and thermally calibrated with an integrated nanoelectromechanical system actuator and a temperature-controlled testing platform respectively. Based on these experimentally-obtained relations, probe mode shifts due to the optomechanical effect are decoupled from those due to the thermo-optic effect. Actuated by the third-order even pump mode, the optomechanical shift of the second-order even probe mode is found to be about 2.5 times its thermal shift, indicating a highly efficient conversion of light energy to mechanical energy.

  15. Temporal characterization of FEL micropulses as function of cavity length detuning using frequency-resolved optical gating

    SciTech Connect

    Richman, B.A.; DeLong, K.W.; Trebino, R.

    1995-12-31

    Results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL system show the effect of FEL cavity length detuning on the micropulse temporal structure. The FROG technique enables the acquisition of complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. The optical pulses are nearly transform limited, and the pulse length increases with cavity length detuning.

  16. Ex vivo laser lipolysis assisted with radially diffusing optical applicator

    NASA Astrophysics Data System (ADS)

    Hwang, Jieun; Hau, Nguyen Trung; Park, Sung Yeon; Rhee, Yun-Hee; Ahn, Jin-Chul; Kang, Hyun Wook

    2016-05-01

    Laser-assisted lipolysis has been implemented to reduce body fat in light of thermal interactions with adipose tissue. However, using a flat fiber with high irradiance often needs rapid cannula movements and even undesirable thermal injury due to direct tissue contact. The aim of the current study was to explore the feasibility of a radially diffusing optical applicator to liquefy the adipose tissue for effective laser lipolysis. The proposed diffuser was evaluated with a flat fiber in terms of temperature elevation and tissue liquefaction after laser lipolysis with a 980-nm wavelength. Given the same power (20 W), the diffusing applicator generated a 30% slower temperature increase with a 25% lower maximum temperature (84±3.2°C in 1 min p<0.001) in the tissue, compared with the flat fiber. Under the equivalent temperature development, the diffuser induced up to fivefold larger area of the adipose liquefaction due to radial light emission than the flat fiber. Ex vivo tissue tests for 5-min irradiation demonstrated that the diffuser (1.24±0.15 g) liquefied 66% more adipose tissue than the flat fiber (0.75±0.05 g). The proposed diffusing applicator can be a feasible therapeutic device for laser lipolysis due to low temperature development and wide coverage of thermal treatment.

  17. Cavity Quantum Electrodynamics: A Universal Quantum Optics Toolbox

    NASA Astrophysics Data System (ADS)

    Rempe, Gerhard

    2016-05-01

    Electromagnetic resonators provide unparalleled capabilities in controlling the interaction between light and matter. The recently developed techniques for trapping and cooling atoms between closely spaced mirrors now open up new experimental avenues for genuine quantum-mechanical experiments. Particularly exciting possibilities concern long-distance quantum networking and scalable quantum computation. Recent achievements like the nondestructive detection of an optical photon, the realization of a quantum gate between a single atom and a single photon, and the heralded and efficient conversion of a flying qubit into a stationary qubit are past highlights. The longstanding dream of a quantum gate between individually addressable photonic qubits might become reality in the future. The talk will summarize recent experiments and give an outlook onto future directions.

  18. Relaxation of crack tip stresses by diffusive growth of grain boundary cavities at a steadily growing creep crack

    SciTech Connect

    Jeon, J.Y. . Dept. of Electronic Materials Engineering)

    1994-02-15

    In this study, the analytic solution of the stress field for the steadily growing crack with Gb cavitation is to be found. The effect of Gb cavitation is simultaneously incorporated in the stress analysis. The macroscopic material behavior is assumed to be elastic, thus, the original stress distribution is determined by the K field of linear elastic fracture mechanics (LEFM). Also, the non-elastic deformation by Gb cavitation relaxes the stress singularity at the crack tip. The stress relaxation by local cavitation is calculated using the dislocation model. For modeling of the cavitation as distributed dislocations, several assumptions can be made: (1) the Gb cavities are nucleated instantaneously at uniformly distributed precipitates when the applied stress reaches the nucleation stress; (2) the quasi-equilibrium type cavity shape is maintained throughout cavity growth because of a sufficiently large surface diffusivity compared to that of Gb diffusivity; (3) the matter flux by diffusion is deposited uniformly at Gb and thus causes rigid body motion which relaxes the elastic stress field.

  19. Diagnosis of cardiovascular diseases based on diffuse optical tomography system

    NASA Astrophysics Data System (ADS)

    Yu, Zong-Han; Wu, Chun-Ming; Lin, Yo-Wei; Chuang, Ming-Lung; Tsai, Jui-che; Sun, Chia-Wei

    2008-02-01

    Diffuse optical tomography (DOT) is a technique to assess the spatial variation in absorption and scattering properties of the biological tissues. DOT provides the measurement of changes in concentrations of oxy-hemoglobin and deoxy-hemoglobin. The oxygenation images are reconstructed by the measured optical signals with nearest-neighbor pairs of sources and detectors. In our study, a portable DOT system is built with optode design on a flexible print circuit board (FPCB). In experiments, the hemodynamics temporal evolution of exercises and vessel occlusions are observed with in vivo measurements form normal subjects and some patients in intensive care unit.

  20. Nonequilibrium phase transition of interacting bosons in an intra-cavity optical lattice.

    PubMed

    Bakhtiari, M Reza; Hemmerich, A; Ritsch, H; Thorwart, M

    2015-03-27

    We investigate the nonlinear light-matter interaction of a Bose-Einstein condensate trapped in an external periodic potential inside an optical cavity which is weakly coupled to vacuum radiation modes and driven by a transverse pump field. Based on a generalized Bose-Hubbard model which incorporates a single cavity mode, we include the collective backaction of the atoms on the cavity light field and determine the nonequilibrium quantum phases within the nonperturbative bosonic dynamical mean-field theory. With the system parameters adapted to recent experiments, we find a quantum phase transition from a normal phase to a self-organized superfluid phase, which is related to the Hepp-Lieb-Dicke superradiance phase transition. For even stronger pumping, a self-organized Mott insulator phase arises.

  1. Low noise planar external cavity laser for interferometric fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Alalusi, Mazin; Brasil, Paul; Lee, Sanggeon; Mols, Peter; Stolpner, Lew; Mehnert, Axel; Li, Steve

    2009-05-01

    A 1550 nm DWDM planar external cavity laser (ECL) is demonstrated to provide low phase/frequency noise, narrow linewidth, and low RIN. The cavity includes a semiconductor gain chip and a planar lightwave circuit waveguide with Bragg grating, packaged in a 14-pin butterfly package. This planar ECL laser is designed to operate under vibration and in harsh environmental conditions. The laser shows linewidth <= 2.6 kHz, phase/frequency noise comparable with that of long cavity fiber lasers, RIN <= -147dB/Hz at 1kHz, and power >= 10mW. Performance is suitable for various high performance fiber optic sensing systems, including interferometric sensing in Oil and Gas, military/security and other applications, currently served mostly by costly and less reliable laser sources.

  2. A crossed optical cavities apparatus for a precision test of the isotropy of light propagation

    NASA Astrophysics Data System (ADS)

    Eisele, Ch.; Okhapkin, M.; Nevsky, A. Yu.; Schiller, S.

    2008-03-01

    A novel apparatus for a sensitive test of the independence of the speed of optical waves from the propagation direction has been developed. It employs a monolithic ULE glass structure containing two orthogonal, crossing Fabry-Perot cavities which enable common mode rejection of certain disturbances. Highly accurate locking and cavity frequency read-out are achieved using laser frequency modulation at audio frequencies. Several systematic effects were characterized. Without rotation the root Allan variance (RAV) of the beat frequency reaches a minimum of 0.5 Hz (2 × 10-15) close to the thermal noise floor of the cavities. The performance of the apparatus under rotation is demonstrated by determining with improved accuracy one parameter of the standard model extension test theory, (κ˜e-)ZZ = (-1.0 ± 2.3) × 10-15, under simplifying assumptions.

  3. An Optically Pumped Far-Infrared Folded Mirror-Less Cavity

    NASA Astrophysics Data System (ADS)

    Liu, Chuang; Wang, Dashuai; Zhang, Peng; Qu, Yanchen

    2017-08-01

    A compact and efficient mirror-less cavity is presented for an optically pumped 192-μm far-infrared laser. With a gold-coated mirror and 30°-inclined anti-reflection coated Ge plate serving as highly reflective mirrors, a folded mirror-less CH3F cavity is achieved. Maximum energy of 0.72 mJ is obtained with the pump energy of 600 mJ, which gives an energy increment of 75% in comparison with the previous 1.85-m mirror-less system. The beam divergence angle of the FIR radiation from this folded mirror-less cavity is measured to be 14.2 mrad.

  4. Commissioning results of Nb3Sn cavity vapor diffusion deposition system at JLab

    SciTech Connect

    Eremeev, Grigory; Clemens, William A.; Macha, Kurt M.; Park, HyeKyoung; Williams, R.

    2015-09-01

    Nb3Sn as a BCS superconductor with a superconducting critical temperature higher than that of niobium offers potential benefit for SRF cavities via a lower-than-niobium surface resistance at the same temperature and frequency. A Nb3Sn vapor diffusion deposition system designed for coating of 1.5 and 1.3 GHz single-cell cavities was built and commissioned at JLab. As the part of the commissioning, RF performance at 2.0 K of a single-cell 1.5 GHz CEBAF-shaped cavity was measured before and after coating in the system. Before Nb3Sn coating the cavity had a Q0 of about 1010 and was limited by the high field Q-slope at Eacc ≅ 27 MV/m. Coated cavity exhibited the superconducting transition at about 17.9 K. The low-field quality factor was about 5∙109 at 4.3 K and 7∙109 at 2.0 K decreasing with field to about 1∙109 at Eacc ≅ 8 MV/m at both temperatures. The highest field was limited by the available RF power.

  5. Use of diffusive optical fibers for plant lighting

    NASA Technical Reports Server (NTRS)

    Kozai, T.; Kitaya, Y.; Fujiwara, K.; Kino, S.; Kinowaki, M.

    1994-01-01

    Lighting is one of the most critical aspects in plant production and environmental research with plants. Much research has been repeated on the effect of light intensity, spectral distribution of light and lighting cycle, but comparatively little research done on the effect of lighting direction on the growth, development and morphology of plants. When plants are grown with lamps above, light is directed downward to the plants. Downward or overhead lighting is utilized in almost all cases. However, downward lighting does not always give the best result in terms of lighting efficiency, growth, development and morphology of plants. In the present study, a sideward lighting system was developed using diffusive optical fiber belts. More higher quality tissue-cultured transplants could be produced in a reduced space with the sideward lighting system than with a downward lighting system. An application of the sideward lighting system using diffusive optical fiber belts is described and the advantages and disadvantages are discussed.

  6. Use of diffusive optical fibers for plant lighting

    NASA Astrophysics Data System (ADS)

    Kozai, T.; Kitaya, Y.; Fujiwara, K.; Kino, S.; Kinowaki, M.

    1994-03-01

    Lighting is one of the most critical aspects in plant production and environmental research with plants. Much research has been repeated on the effect of light intensity, spectral distribution of light and lighting cycle, but comparatively little research done on the effect of lighting direction on the growth, development and morphology of plants. When plants are grown with lamps above, light is directed downward to the plants. Downward or overhead lighting is utilized in almost all cases. However, downward lighting does not always give the best result in terms of lighting efficiency, growth, development and morphology of plants. In the present study, a sideward lighting system was developed using diffusive optical fiber belts. More higher quality tissue-cultured transplants could be produced in a reduced space with the sideward lighting system than with a downward lighting system. An application of the sideward lighting system using diffusive optical fiber belts is described and the advantages and disadvantages are discussed.

  7. An extended analytical approach for diffuse optical imaging.

    PubMed

    Erkol, H; Nouizi, F; Unlu, M B; Gulsen, G

    2015-07-07

    In this work, we introduce an analytical method to solve the diffusion equation in a cylindrical geometry. This method is based on an integral approach to derive the Green's function for specific boundary conditions. Using our approach, we obtain comprehensive analytical solutions with the Robin boundary condition for diffuse optical imaging in both two and three dimensions. The solutions are expressed in terms of the optical properties of tissue and the amplitude and position of the light source. Our method not only works well inside the tissue but provides very accurate results near the tissue boundaries as well. The results obtained by our method are first compared with those obtained by a conventional analytical method then validated using numerical simulations. Our new analytical method allows not only implementation of any boundary condition for a specific problem but also fast simulation of light propagation making it very suitable for iterative image reconstruction algorithms.

  8. Diffuse optical tomography based on multiple access coding

    NASA Astrophysics Data System (ADS)

    Wang, Xuefeng; Wang, Yuanqing; Su, Jinshan; Xu, Fan

    2016-04-01

    Diffuse optical tomography (DOT) has the advantages of being a non-invasive, non-radiation emitting and low-cost biological tissue imaging method, and many recent studies have employed this technology. By improving the spatial resolution and developing a new method for constantly improving the flexibility of the experimental device, the system can perform data acquisition rapidly and conveniently. We propose a method for rapid data acquisition based on multiple access coding; it can acquire data in parallel, and the system can greatly improve the temporal resolution of the data acquisition step in diffuse optical tomography thereafter. We simulate the encoding and decoding process of the source-detector pair and successfully isolate the source signal from mixed signals. The DOT image reconstruction highlight the effectiveness of the system.

  9. Numerical modelling and image reconstruction in diffuse optical tomography

    PubMed Central

    Dehghani, Hamid; Srinivasan, Subhadra; Pogue, Brian W.; Gibson, Adam

    2009-01-01

    The development of diffuse optical tomography as a functional imaging modality has relied largely on the use of model-based image reconstruction. The recovery of optical parameters from boundary measurements of light propagation within tissue is inherently a difficult one, because the problem is nonlinear, ill-posed and ill-conditioned. Additionally, although the measured near-infrared signals of light transmission through tissue provide high imaging contrast, the reconstructed images suffer from poor spatial resolution due to the diffuse propagation of light in biological tissue. The application of model-based image reconstruction is reviewed in this paper, together with a numerical modelling approach to light propagation in tissue as well as generalized image reconstruction using boundary data. A comprehensive review and details of the basis for using spatial and structural prior information are also discussed, whereby the use of spectral and dual-modality systems can improve contrast and spatial resolution. PMID:19581256

  10. Signal filtering algorithm for depth-selective diffuse optical topography

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Nakayama, K.

    2009-03-01

    A compact filtered backprojection algorithm that suppresses the undesirable effects of skin circulation for near-infrared diffuse optical topography is proposed. Our approach centers around a depth-selective filtering algorithm that uses an inverse problem technique and extracts target signals from observation data contaminated by noise from a shallow region. The filtering algorithm is reduced to a compact matrix and is therefore easily incorporated into a real-time system. To demonstrate the validity of this method, we developed a demonstration prototype for depth-selective diffuse optical topography and performed both computer simulations and phantom experiments. The results show that the proposed method significantly suppresses the noise from the shallow region with a minimal degradation of the target signal.

  11. Monitoring the evaporation of fluids from fiber-optic micro-cell cavities.

    PubMed

    Preter, Eyal; Preloznik, Borut; Artel, Vlada; Sukenik, Chaim N; Donlagic, Denis; Zadok, Avi

    2013-11-07

    Fiber-optic sensors provide remote access, are readily embedded within structures, and can operate in harsh environments. Nevertheless, fiber-optic sensing of liquids has been largely restricted to measurements of refractive index and absorption spectroscopy. The temporal dynamics of fluid evaporation have potential applications in monitoring the quality of water, identification of fuel dilutions, mobile point-of-care diagnostics, climatography and more. In this work, the fiber-optic monitoring of fluids evaporation is proposed and demonstrated. Sub-nano-liter volumes of a liquid are applied to inline fiber-optic micro-cavities. As the liquid evaporates, light is refracted out of the cavity at the receding index boundary between the fluid and the ambient surroundings. A sharp transient attenuation in the transmission of light through the cavity, by as much as 50 dB and on a sub-second time scale, is observed. Numerical models for the transmission dynamics in terms of ray-tracing and wavefront propagation are provided. Experiments show that the temporal transmission profile can distinguish between different liquids.

  12. Monitoring the Evaporation of Fluids from Fiber-Optic Micro-Cell Cavities

    PubMed Central

    Preter, Eyal; Preloznik, Borut; Artel, Vlada; Sukenik, Chaim N.; Donlagic, Denis; Zadok, Avi

    2013-01-01

    Fiber-optic sensors provide remote access, are readily embedded within structures, and can operate in harsh environments. Nevertheless, fiber-optic sensing of liquids has been largely restricted to measurements of refractive index and absorption spectroscopy. The temporal dynamics of fluid evaporation have potential applications in monitoring the quality of water, identification of fuel dilutions, mobile point-of-care diagnostics, climatography and more. In this work, the fiber-optic monitoring of fluids evaporation is proposed and demonstrated. Sub-nano-liter volumes of a liquid are applied to inline fiber-optic micro-cavities. As the liquid evaporates, light is refracted out of the cavity at the receding index boundary between the fluid and the ambient surroundings. A sharp transient attenuation in the transmission of light through the cavity, by as much as 50 dB and on a sub-second time scale, is observed. Numerical models for the transmission dynamics in terms of ray-tracing and wavefront propagation are provided. Experiments show that the temporal transmission profile can distinguish between different liquids. PMID:24212122

  13. Real-time optical motion correction for diffusion tensor imaging.

    PubMed

    Aksoy, Murat; Forman, Christoph; Straka, Matus; Skare, Stefan; Holdsworth, Samantha; Hornegger, Joachim; Bammer, Roland

    2011-08-01

    Head motion is a fundamental problem in brain MRI. The problem is further compounded in diffusion tensor imaging because of long acquisition times, and the sensitivity of the tensor computation to even small misregistration. To combat motion artifacts in diffusion tensor imaging, a novel real-time prospective motion correction method was introduced using an in-bore monovision system. The system consists of a camera mounted on the head coil and a self-encoded checkerboard marker that is attached to the patient's forehead. Our experiments showed that optical prospective motion correction is more effective at removing motion artifacts compared to image-based retrospective motion correction. Statistical analysis revealed a significant improvement in similarity between diffusion data acquired at different time points when prospective correction was used compared to retrospective correction (P<0.001). Copyright © 2011 Wiley-Liss, Inc.

  14. Concentrating partially entangled W-class states on nonlocal atoms using low- Q optical cavity and linear optical elements

    NASA Astrophysics Data System (ADS)

    Cao, Cong; Chen, Xi; Duan, YuWen; Fan, Ling; Zhang, Ru; Wang, TieJun; Wang, Chuan

    2016-10-01

    Entanglement plays an important role in quantum information science, especially in quantum communications. Here we present an efficient entanglement concentration protocol (ECP) for nonlocal atom systems in the partially entangled W-class states, using the single-photon input-output process regarding low- Q cavity and linear optical elements. Compared with previously published ECPs for the concentration of non-maximally entangled atomic states, our protocol is much simpler and more efficient as it employs the Faraday rotation in cavity quantum electrodynamics (QED) and the parameter-splitting method. The Faraday rotation requires the cavity with low- Q factor and weak coupling to the atom, which makes the requirement for entanglement concentration much less stringent than the previous methods, and achievable with current cavity QED techniques. The parameter-splitting method resorts to linear-optical elements only. This ECP has high efficiency and fidelity in realistic experiments, and some imperfections during the experiment can be avoided efficiently with currently available techniques.

  15. Cavity Self-Stabilization and Enhancement of Laser Gyroscopes by (Coupled) Optical Resonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2006-01-01

    We analyze the effect of a highly dispersive element placed inside a modulated optical cavity on the frequency and amplitude of the modulation to determine the conditions for cavity self-stabilization and enhanced gyroscopic sensitivity. Hence, we model cavity rotation or instability by an arbitrary AM/FM modulation, and the dispersive element as a phase and amplitude filter. We find that anomalous dispersion may be used to self-stabilize a laser cavity, provided the magnitude of the group index of refraction is smaller than the phase index of refraction in the cavity. The optimal stabilization is found to occur when the group index is zero. Group indices with magnitudes larger than the phase index (both normal and anomalous dispersion) are found to enhance the sensitivity of a laser gyroscope to rotation. Furthermore, our results indicate that atomic media, even coherent superpositions in multilevel atoms, are not useful for these applications, because the amplitude and phase filters work against one another, i.e., decreasing the modulation frequency increases its amplitude and vice versa, with one exception: negative group indices whose magnitudes are larger than the phase index result in negative, but enhanced, beat frequencies. On the other hand, for optical resonators the dispersion reversal associated with critical coupling enables the amplitude and phase filters to work together under a greater variety of circumstances than for atomic media. We find that for single over-coupled resonators, or in the case of under-coupled coupled-resonator-induced absorption, the absorption and normal dispersion on-resonance increase the contrast and frequency of the beat-note, respectively, resulting in a substantial enhancement of the gyroscopic response. Moreover, for cavity self-stabilization, we propose the use of a variety of coupled-resonator induced transparency that is accompanied by anomalous dispersion.

  16. All-optical phase modulation in a cavity-polariton Mach–Zehnder interferometer

    PubMed Central

    Sturm, C.; Tanese, D.; Nguyen, H.S.; Flayac, H.; Galopin, E.; Lemaître, A.; Sagnes, I.; Solnyshkov, D.; Amo, A.; Malpuech, G.; Bloch, J.

    2014-01-01

    Quantum fluids based on light is a highly developing research field, since they provide a nonlinear platform for developing optical functionalities and quantum simulators. An important issue in this context is the ability to coherently control the properties of the fluid. Here we propose an all-optical approach for controlling the phase of a flow of cavity-polaritons, making use of their strong interactions with localized excitons. Here we illustrate the potential of this method by implementing a compact exciton–polariton interferometer, which output intensity and polarization can be optically controlled. This interferometer is cascadable with already reported polariton devices and is promising for future polaritonic quantum optic experiments. Complex phase patterns could be also engineered using this optical method, providing a key tool to build photonic artificial gauge fields. PMID:24513781

  17. Comprehensive vertical-cavity surface-emitting laser model for optical interconnect transceiver circuit design

    NASA Astrophysics Data System (ADS)

    Wang, Binhao; Sorin, Wayne V.; Palermo, Samuel; Tan, Michael R. T.

    2016-12-01

    Directly modulated vertical-cavity surface-emitting lasers (VCSELs) are commonly used in short-reach optical interconnect applications. To enable efficient optical interconnect transceiver systems operating at data rates up to 25 Gb/s and beyond, cosimulation environments, which allow for the optimization of driver circuitry with accurate compact VCSEL models, are necessary. A comprehensive VCSEL model, which captures thermally dependent electrical and optical dynamics and provides direct current, small-, and large-signal simulation capabilities with self-consistency, is presented. The device's electrical behavior is described with an equivalent circuit, which captures both large-signal operation and electrical parasitics, while the optical response is captured with a rate-equation-based model. Bias and temperature dependencies are incorporated into both key electrical and optical model parameters. Experimental verification of the model is performed at 25 Gb/s with a 990-nm VCSEL to study the impact of bias current level and substrate temperature.

  18. Functional imaging of small tissue volumes with diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Klose, Alexander D.; Hielscher, Andreas H.

    2006-03-01

    Imaging of dynamic changes in blood parameters, functional brain imaging, and tumor imaging are the most advanced application areas of diffuse optical tomography (DOT). When dealing with the image reconstruction problem one is faced with the fact that near-infrared photons, unlike X-rays, are highly scattered when they traverse biological tissue. Image reconstruction schemes are required that model the light propagation inside biological tissue and predict measurements on the tissue surface. By iteratively changing the tissue-parameters until the predictions agree with the real measurements, a spatial distribution of optical properties inside the tissue is found. The optical properties can be related to the tissue oxygenation, inflammation, or to the fluorophore concentration of a biochemical marker. If the model of light propagation is inaccurate, the reconstruction process will lead to an inaccurate result as well. Here, we focus on difficulties that are encountered when DOT is employed for functional imaging of small tissue volumes, for example, in cancer studies involving small animals, or human finger joints for early diagnosis of rheumatoid arthritis. Most of the currently employed image reconstruction methods rely on the diffusion theory that is an approximation to the equation of radiative transfer. But, in the cases of small tissue volumes and tissues that contain low scattering regions diffusion theory has been shown to be of limited applicability Therefore, we employ a light propagation model that is based on the equation of radiative transfer, which promises to overcome the limitations.

  19. Scheme for generating the singlet state of three atoms trapped in distant cavities coupled by optical fibers

    SciTech Connect

    Wang, Dong-Yang; Wen, Jing-Ji; Bai, Cheng-Hua; Hu, Shi; Cui, Wen-Xue; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2015-09-15

    An effective scheme is proposed to generate the singlet state with three four-level atoms trapped in three distant cavities connected with each other by three optical fibers, respectively. After a series of appropriate atom–cavity interactions, which can be arbitrarily controlled via the selective pairing of Raman transitions and corresponding optical switches, a three-atom singlet state can be successfully generated. The influence of atomic spontaneous decay, photon leakage of cavities and optical fibers on the fidelity of the state is numerically simulated showing that the three-atom singlet state can be generated with high fidelity by choosing the experimental parameters appropriately.

  20. Microstructured optical fiber-based micro-cavity sensor for chemical detection

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Ahn, Jin-Chul; Chung, Phil-Sang; Chung, Youngjoo

    2014-02-01

    The studies on microstructured optical fibers (MOF) have drawn considerable interest and played an important role in many applications. MOFs provide unique optical properties and controllable modal properties because of their flexibilities on manipulation of the transmission spectrum and the waveguide dispersion properties. MOFs are especially useful for optical sensing applications because the micro-structured air channels in MOF can host various types of analytes such as liquids, gases, and chemical molecules. Recently, many studies have focused on the development of MOF-based optical sensors for various gases and chemical molecules. We propose a compact, and highly sensitive optical micro-cavity chemical sensor using microstructured fiber. The sensor probe is composed of a hollow optical fiber and end cleaved microstructured fiber with a solid core. The interference spectrum resulting from the reflected light at the silica and air interfaces changes when the micro-cavity is infiltrated with external chemical molecules. This structure enables the direct detection of chemical molecules such as volatile organic compounds (VOCs) without the introduction of any permeable material.

  1. Optical surface properties and their RF limitations of European XFEL cavities

    NASA Astrophysics Data System (ADS)

    Wenskat, Marc

    2017-10-01

    The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. The industrial fabrication of cavities for the European X-ray Free Electron Laser and the International Linear Collider HiGrade Research Project allowed for an investigation of this interplay. For the serial inspection of the inner surface, the optical inspection robot ’optical bench for automated cavity inspection with high resolution on short timescales’ OBACHT was constructed and to analyze the large amount of data, represented in the images of the inner surface, an image processing and analysis code was developed and new variables to describe the cavity surface were obtained. This quantitative analysis identified vendor-specific surface properties which allow the performance of quality control and assurance during production. In addition, a strong negative correlation of ρ =-0.93 with a significance of 6 σ of the integrated grain boundary area \\sum {A} versus the maximal achievable accelerating field {{E}}{acc,\\max } has been found.

  2. Intracavity Rydberg-atom electromagnetically induced transparency using a high-finesse optical cavity

    NASA Astrophysics Data System (ADS)

    Sheng, Jiteng; Chao, Yuanxi; Kumar, Santosh; Fan, Haoquan; Sedlacek, Jonathon; Shaffer, James P.

    2017-09-01

    We present an experimental study of cavity-assisted Rydberg-atom electromagnetically induced transparency (EIT) using a high-finesse optical cavity (F ˜28 000 ). Rydberg atoms are excited via a two-photon transition in a ladder-type EIT configuration. A three-peak structure of the cavity transmission spectrum is observed when Rydberg EIT is generated inside the cavity. The two symmetrically spaced side peaks are caused by bright-state polaritons, while the central peak corresponds to a dark-state polariton. Anticrossing phenomena and the effects of mirror adsorbate electric fields are studied under different experimental conditions. We determine a lower bound on the coherence time for the system of 7.26 ±0.06 μ s , most likely limited by laser dephasing. The cavity-Rydberg EIT system can be useful for single-photon generation using the Rydberg blockade effect, studying many-body physics, and generating novel quantum states among many other applications.

  3. Model reduction of cavity nonlinear optics for photonic logic: a quasi-principal components approach

    NASA Astrophysics Data System (ADS)

    Shi, Zhan; Nurdin, Hendra I.

    2016-11-01

    Kerr nonlinear cavities displaying optical thresholding have been proposed for the realization of ultra-low power photonic logic gates. In the ultra-low photon number regime, corresponding to energy levels in the attojoule scale, quantum input-output models become important to study the effect of unavoidable quantum fluctuations on the performance of such logic gates. However, being a quantum anharmonic oscillator, a Kerr-cavity has an infinite dimensional Hilbert space spanned by the Fock states of the oscillator. This poses a challenge to simulate and analyze photonic logic gates and circuits composed of multiple Kerr nonlinearities. For simulation, the Hilbert of the oscillator is typically truncated to the span of only a finite number of Fock states. This paper develops a quasi-principal components approach to identify important subspaces of a Kerr-cavity Hilbert space and exploits it to construct an approximate reduced model of the Kerr-cavity on a smaller Hilbert space. Using this approach, we find a reduced dimension model with a Hilbert space dimension of 15 that can closely match the magnitudes of the mean transmitted and reflected output fields of a conventional truncated Fock state model of dimension 75, when driven by an input coherent field that switches between two levels. For the same input, the reduced model also closely matches the magnitudes of the mean output fields of Kerr-cavity-based AND and NOT gates and a NAND latch obtained from simulation of the full 75 dimension model.

  4. Feasibility of interstitial diffuse optical tomography using cylindrical diffusing fiber for prostate PDT

    PubMed Central

    Liang, Xing; Wang, Ken Kang-Hsin; Zhu, Timothy C.

    2013-01-01

    Interstitial diffuse optical tomography (DOT) has been used to characterize spatial distribution of optical properties for prostate photodynamic therapy (PDT) dosimetry. We have developed an interstitial DOT method using cylindrical diffuse fibers (CDFs) as light sources, so that the same light sources can be used for both DOT measurement and PDT treatment. In this novel interstitial CDF-DOT method, absolute light fluence per source strength (in unit of 1/cm2) is used to separate absorption and scattering coefficients. A mathematical phantom and a solid prostate phantom including anomalies with known optical properties were used, respectively, to test the feasibility of reconstructing optical properties using interstitial CDF-DOT. Three dimension spatial distributions of the optical properties were reconstructed for both scenarios. Our studies show that absorption coefficient can be reliably extrapolated while there are some cross talks between absorption and scattering properties. Even with the suboptimal reduced scattering coefficients, the reconstructed light fluence rate agreed with the measured values to within ±10%, thus the proposed CDF-DOT allows greatly improved light dosimetry calculation for interstitial PDT. PMID:23629149

  5. Molecular imaging of water binding state and diffusion in breast cancer using diffuse optical spectroscopy and diffusion weighted MRI

    NASA Astrophysics Data System (ADS)

    Chung, So Hyun; Yu, Hon; Su, Min-Ying; Cerussi, Albert E.; Tromberg, Bruce J.

    2012-07-01

    Tissue water content and molecular microenvironment can provide important intrinsic contrast for cancer imaging. In this work, we examine the relationship between water optical spectroscopic features related to binding state and magnetic resonance imaging (MRI)-measured water diffusion dynamics. Broadband diffuse optical spectroscopic imaging (DOSI) and MR images were obtained from eight patients with locally-advanced infiltrating ductal carcinomas (tumor size=5.5±3.2 cm). A DOSI-derived bound water index (BWI) was compared to the apparent diffusion coefficient (ADC) of diffusion weighted (DW) MRI. BWI and ADC were positively correlated (R=0.90, p-value=0.003) and BWI and ADC both decreased as the bulk water content increased (R=-0.81 and -0.89, respectively). BWI correlated inversely with tumor size (R=-0.85, p-value=0.008). Our results suggest underlying sensitivity differences between BWI and ADC to water in different tissue compartments (e.g., extracellular vs cellular). These data highlight the potential complementary role of DOSI and DW-MRI in providing detailed information on the molecular disposition of water in breast tumors. Because DOSI is a portable technology that can be used at the bedside, BWI may provide a low-cost measure of tissue water properties related to breast cancer biology.

  6. Quantum theory of spontaneous emission in a one-dimensional optical cavity with two-side output coupling

    NASA Astrophysics Data System (ADS)

    Feng, Xiao-Ping; Ujihara, Kikuo

    1990-03-01

    A quantum theory of spontaneous emission from an initially excited two-level atom in a one-dimensional optical cavity with output coupling from both sides is developed. Orthonormal mode functions with a continuous spectrum are employed, which are derived by imposing a periodic boundary condition on the whole space with a period much larger than the cavity length. The delay differential equation of the atomic state of Cook and Milonni [Phys. Rev. A 35, 5081 (1987)] is re-derived in a strict manner, where the reflectivity of the cavity mirrors is included naturally in the mode functions. An approximate solution at a single-resonant-mode limit shows the results of ``vacuum'' Rabi oscillation in an underdamped cavity and enhanced spontaneous emission rate in an overdamped cavity. For the latter case, it is found that in the optical range the spontaneous emission rate is enhanced by a factor F (finesse of the cavity).

  7. Optical cavity characterization of the Tor Vergata Fabry-Pérot interferometer

    NASA Astrophysics Data System (ADS)

    Giovannelli, Luca; Berrilli, Francesco; Del Moro, Dario; Greco, Vincenzo; Piazzesi, Roberto; Sordini, Andrea; Stangalini, Marco

    2014-08-01

    We report the first optical and control performances of the Tor Vergata Fabry-Ṕerot interferometer prototype designed and realized in the framework of the ADvanced Astronomy for HELIophysics (ADAHELI) solar mission project. The characterization of the the coated surfaces of the two plates defining the optical cavity has been carried out with a Zygo interferometer able to measure the microroughness and global curvature of the cavity. The peak-to-valley errors are compliant with the manufacturer specifications and correspond to λ/70 and λ/80 @632.8 nm respectively. In addition, we present a first estimate of the interferometer spectral stability in stable open-air condition. A spectral uncertainty equal to 0.95 pm is found as the typical RMS over one hour of the passband central wavelength position.

  8. Quantum mixed phases of a two-dimensional polarized degenerate Fermi gas in an optical cavity.

    PubMed

    Feng, Yanlin; Zhang, Kuang; Fan, Jingtao; Mei, Feng; Chen, Gang; Jia, Suotang

    2017-09-05

    The coupling of ultracold fermions to a high-finesse optical cavity can result in novel many-body phenomena, and has attracted significant interests at present. Here we consider a realization of the Fermi-Dicke model with controllable parameters, based on a two-dimensional polarized degenerate Fermi gas coupled to an optical cavity. We analytically investigate the ground-state properties of such system under the mean-field approximation. We find the system can exhibit a rich phase diagram depending on the fermion-photon coupling strength and the atomic resonant frequency. Contrasting to the bosonic counterpart, a first-order quantum phase transition between the superradiant phase and the normal phase featuring two Fermi surfaces can occur for the weak atomic resonant frequency, and there is a unique mixed phase where this normal phase and the superradiant phase coexist. The experimental detection of our results is also discussed.

  9. Surface plasmon polaritons in a topological insulator embedded in an optical cavity

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-03-17

    Very recently, the surface plasmons in a topological insulator (TI) have been experimentally observed by exciting these collective modes with polarized light [P. Di Pietro, M. Ortolani, O. Limaj, A. Di Gaspare, V. Giliberti, F. Giorgianni, M. Brahlek, N. Bansal, N. Koirala, S. Oh, P. Calvani, and S. Lupi, Nat. Nanotechnol. 8, 556 (2013)]. Motivated by this experimental work, here we present a theoretical study on the surface plasmon polaritons (SPPs) induced by plasmon-photon interactions in a TI thin film embedded in an optical cavity. It is found that the frequencies of SPP modes are within the terahertz (THz) bandwidth and can be tuned effectively by adjusting the surface electron density and/or the optical cavity length. Since the surface electron density can be well controlled by the gate-voltage applied perpendicular to the TI surface, our theoretical results indicate that gated TI thin films may have potential applications in the electrically tunable THz plasmonic devices.

  10. Feedback control of thermal lensing in a high optical power cavity.

    PubMed

    Fan, Y; Zhao, C; Degallaix, J; Ju, L; Blair, D G; Slagmolen, B J J; Hosken, D J; Brooks, A F; Veitch, P J; Munch, J

    2008-10-01

    This paper reports automatic compensation of strong thermal lensing in a suspended 80 m optical cavity with sapphire test mass mirrors. Variation of the transmitted beam spot size is used to obtain an error signal to control the heating power applied to the cylindrical surface of an intracavity compensation plate. The negative thermal lens created in the compensation plate compensates the positive thermal lens in the sapphire test mass, which was caused by the absorption of the high intracavity optical power. The results show that feedback control is feasible to compensate the strong thermal lensing expected to occur in advanced laser interferometric gravitational wave detectors. Compensation allows the cavity resonance to be maintained at the fundamental mode, but the long thermal time constant for thermal lensing control in fused silica could cause difficulties with the control of parametric instabilities.

  11. High-finesse cavity external optical feedback DFB laser with hertz relative linewidth.

    PubMed

    Zhao, Yang; Wang, Qiang; Meng, Fei; Lin, Yige; Wang, Shaokai; Li, Ye; Lin, Baike; Cao, Shiying; Cao, Jianping; Fang, Zhanjun; Li, Tianchu; Zang, Erjun

    2012-11-15

    We report hertz level relative linewidth distributed feedback diode lasers with external optical feedback from a high finesse F-P cavity, and demonstrate the efficient phase noise suppression and laser linewidth reduction of the optical feedback technique. The laser phase noise is dramatically suppressed throughout the measurement frequency range. Especially at the Fourier frequency of 17 kHz, approximately the linewidth of the F-P reference cavity, the laser phase noise is significantly suppressed by more than 92 dB. Above this Fourier frequency, the noise maintains a white phase noise plateau as low as -124.4 dBc/Hz. The laser's FWHM linewidth is reduced from 7 MHz to 4.4 Hz, and its instantaneous linewidth is 220 mHz in the Lorentzian fitting.

  12. Passive intrinsic-linewidth narrowing of ultraviolet extended-cavity diode laser by weak optical feedback.

    PubMed

    Samutpraphoot, Polnop; Weber, Sophie; Lin, Qian; Gangloff, Dorian; Bylinskii, Alexei; Braverman, Boris; Kawasaki, Akio; Raab, Christoph; Kaenders, Wilhelm; Vuletić, Vladan

    2014-05-19

    We present a simple method for narrowing the intrinsic Lorentzian linewidth of a commercial ultraviolet grating extended-cavity diode laser (TOPTICA DL Pro) using weak optical feedback from a long external cavity. We achieve a suppression in frequency noise spectral density of 20 dB measured at frequencies around 1 MHz, corresponding to the narrowing of the intrinsic Lorentzian linewidth from 200 kHz to 2 kHz. Provided additional active low-frequency noise suppression and long-term drift compensation, the system is suitable for experiments requiring a tunable ultraviolet laser with narrow linewidth and low high-frequency noise, such as precision spectroscopy, optical clocks, and quantum information science experiments.

  13. All-optical switching in silicon-on-insulator photonic wire nano-cavities.

    PubMed

    Belotti, Michele; Galli, Matteo; Gerace, Dario; Andreani, Lucio Claudio; Guizzetti, Giorgio; Md Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

    2010-01-18

    We report on experimental demonstration of all-optical switching in a silicon-on-insulator photonic wire nanocavity operating at telecom wavelengths. The switching is performed with a control pulse energy as low as approximately 0.1 pJ on a cavity device that presents very high signal transmission, an ultra-high quality-factor, almost diffraction-limited modal volume and a footprint of only 5 microm(2). High-speed modulation of the cavity mode is achieved by means of optical injection of free carriers using a nanosecond pulsed laser. Experimental results are interpreted by means of finite-difference time-domain simulations. The possibility of using this device as a logic gate is also demonstrated.

  14. Diffuse optical imaging of brain activation to joint attention experience.

    PubMed

    Zhu, Banghe; Yadav, Nitin; Rey, Gustavo; Godavarty, Anuradha

    2009-08-24

    In the early development of social cognition and language, infants tend to participate in face-to-face interactions engaging in joint attention exchanges. Joint attention is vital to social competence at all ages, lacking which is a primary feature to distinguish autistic from non-autistic population. In this study, diffuse optical imaging is used for the first time to investigate the joint attention experience in normal adults. Imaging studies were performed in the frontal regions of the brain (BA9 and BA10) in order to study the differences in the brain activation in response to video clips corresponding to joint attention based skills. The frontal regions of the brain were non-invasively imaged using a novel optical cap coupled to a frequency-domain optical imaging system. The statistical analysis from 11 normal adult subjects, with three repetitions from each subject, indicated that the averaged changes in the cerebral blood oxygenation levels were different under the joint and non-joint attention based stimulus. The preliminary studies demonstrate the feasibility of implementing diffuse optical imaging towards autism-related research to study the brain activation in response to socio-communication skills.

  15. Diffuse optical tomography using multichannel robotic platform for interstitial PDT

    PubMed Central

    Sharikova, Anna V.; Liang, Xing; Zhu, Timothy C.

    2015-01-01

    In the operating room, time is extremely precious, and the speed of one’s data acquisition system often determines whether the data will be taken or not. Our multichannel robotic platform addresses this issue by optimizing source and detector scanning procedures. Up to 16 fibers can be moved independently with resolution of 0.05 mm and speed of 50 mm/s using motors with position feedback. The initial fiber alignment employs a light beam/optical detector system for identical positioning of all motors. Peak and edge detection algorithms, for point and linear sources, are used with multiple fibers simultaneously for fast realignment of sources and detectors. The robotic platform is used to perform Diffuse Optical Tomography (DOT) measurements in solid prostate phantoms with both homogenous and inhomogeneous Optical Properties (OP). Correct positioning is critical for the accurate recovery of the OP. The light fluence rate distribution is determined by scanning multiple detector fibers simultaneously along lit linear sources placed throughout the phantom volume inside catheter needles. The scanning time for the entire DOT is about 10 seconds after the initial alignment. The OP distribution reconstruction is based on the steady-state light diffusion equation. The inverse interstitial DOT problem is solved using NIRFAST. The optical properties are recovered by iterative minimization of the difference between measured and calculated light fluence rates. Recovered OP agree with the actual values within 10%. The OP corrections are used to significantly improve light fluence accuracy for the entire volume of bulk tumor. PMID:25999650

  16. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    PubMed

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  17. Compact efficient eye-safe intracavity optical parametric oscillator with a shared cavity configuration

    SciTech Connect

    Chen, Y. F.; Su, K. W.; Chang, Y. T.; Yen, W. C

    2007-06-10

    We present a compact efficient eye-safe intracavity optical parametric oscillator pumpedby a passively Q-switched Nd:YAG laser in a shared cavity configuration. A signal pulse of 3.3 mJ energy at a 1573 nm wavelength with a peak power of150 kW was achieved. The effective conversion efficiency with respective to the optimized 1064 nm Q-switched pulse energy was as high as 51%.

  18. Cavity-enhanced optical trapping of bacteria using a silicon photonic crystal.

    PubMed

    van Leest, Thijs; Caro, Jacob

    2013-11-21

    On-chip optical trapping and manipulation of cells based on the evanescent field of photonic structures is emerging as a promising technique, both in research and for applications in broader context. Relying on mass fabrication techniques, the involved integration of photonics and microfluidics allows control of both the flow of light and water on the scale of interest in single cell microbiology. In this paper, we demonstrate for the first time optical trapping of single bacteria (B. subtilis and E. coli) using photonic crystal cavities for local enhancement of the evanescent field, as opposed to the synthetic particles used so far. Three types of cavities (H0, H1 and L3) are studied, embedded in a planar photonic crystal and optimized for coupling to two collinear photonic crystal waveguides. The photonic crystals are fabricated on a silicon-on-insulator chip, onto which a fluidic channel is created as well. For each of the cavities, when pumped at the resonance wavelength (around 1550 nm), we clearly demonstrate optical trapping of bacteria, in spite of their low index contrast w.r.t. water. By tracking the confined Brownian motion of B. subtilis spores in the traps using recorded microscope observations, we derive strong in-plane trap stiffnesses of about 7.6 pN nm(-1) W(-1). The values found agree very well with calculations based on the Maxwell stress tensor for the force and finite-difference time-domain simulations of the fields for the fabricated cavity geometries. We envision that our lab-on-a-chip with photonic crystal traps opens up new application directions, e.g. immobilization of single bio-objects such as mammalian cells and bacteria under controlled conditions for optical microscopy studies.

  19. Mapping distributed brain function and networks with diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Eggebrecht, Adam T.; Ferradal, Silvina L.; Robichaux-Viehoever, Amy; Hassanpour, Mahlega S.; Dehghani, Hamid; Snyder, Abraham Z.; Hershey, Tamara; Culver, Joseph P.

    2014-06-01

    Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted metal and electronic devices (for example, pacemakers). However, optical imaging technology has heretofore lacked the combination of spatial resolution and wide field of view sufficient to map distributed brain functions. Here, we present a high-density diffuse optical tomography imaging array that can map higher-order, distributed brain function. The system was tested by imaging four hierarchical language tasks and multiple resting-state networks including the dorsal attention and default mode networks. Finally, we imaged brain function in patients with Parkinson's disease and implanted deep brain stimulators that preclude functional magnetic resonance imaging.

  20. Temperature Sensitivity of an Atomic Vapor Cell-Based Dispersion-Enhanced Optical Cavity

    NASA Technical Reports Server (NTRS)

    Myneni, K.; Smith, D. D.; Chang, H.; Luckay, H. A.

    2015-01-01

    Enhancement of the response of an optical cavity to a change in optical path length, through the use of an intracavity fast-light medium, has previously been demonstrated experimentally and described theoretically for an atomic vapor cell as the intracavity resonant absorber. This phenomenon may be used to enhance both the scale factor and sensitivity of an optical cavity mode to the change in path length, e.g. in gyroscopic applications. We study the temperature sensitivity of the on-resonant scale factor enhancement, S(sub o), due to the thermal sensitivity of the lower-level atom density in an atomic vapor cell, specifically for the case of the Rb-87 D(sub 2) transition. A semi-empirical model of the temperature-dependence of the absorption profile, characterized by two parameters, a(sub o)(T) and gamma(sub a)(T) allows the temperature-dependence of the cavity response, S(sub o)(T) and dS(sub o)/dT to be predicted over a range of temperature. We compare the predictions to experiment. Our model will be useful in determining the useful range for S(sub o), given the practical constraints on temperature stability for an atomic vapor cell.

  1. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    DOE PAGES

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; ...

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength goldmore » disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.« less

  2. Direct measurement of optical force induced by near-field plasmonic cavity using dynamic mode AFM

    SciTech Connect

    Guan, Dongshi; Hang, Zhi Hong; Marset, Zsolt; Liu, Hui; Kravchenko, Ivan I.; Chan, Ho Bun; Chan, C. T.; Tong, Penger

    2015-11-20

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. Lastly, the experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures.

  3. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    PubMed Central

    Guan, Dongshi; Hang, Zhi Hong; Marcet, Zsolt; Liu, Hui; Kravchenko, I. I.; Chan, C. T.; Chan, H. B.; Tong, Penger

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optical force acting on a nano-structured plasmonic resonant cavity. The plasmonic cavity is made of an upper gold-coated glass sphere and a lower quartz substrate patterned with an array of subwavelength gold disks. In the near-field when the sphere is positioned close to the disk array, plasmonic resonance is excited in the cavity and the induced force by a 1550 nm infrared laser is found to be increased by an order of magnitude compared with the photon pressure generated by the same laser light. The experiment demonstrates that DM-AFM is a powerful tool for the study of light induced forces and their enhancement in plasmonic nanostructures. PMID:26586455

  4. Compact double optical feedback external-cavity diode laser system and its frequency stabilization

    NASA Astrophysics Data System (ADS)

    Doi, Kohei; Minabe, Yuta; Sato, Takashi; Maruyama, Takeo; Ohkawa, Masashi; Tsubokawa, Tsuneya

    2007-02-01

    External cavity diode laser (ECDL) systems are presently experiencing a surge in popularity as laser light-sources, in advanced optical communications- and measurement-systems. Because such systems require that their external reflectors be precisely controlled, to eliminate low frequency fluctuations (LFF) in optical output, we conducted experiments with a two-cavity version, which easily eliminated LFFs, as expected. The technique has the added advantage of a narrower oscillation-linewidth than would be achievable, using a single optical feedback. However, the ECDL's oscillation frequency is susceptible to the influences of the drive-current, as well as changes, both in the refractive index, and the overall length of the external reflector that results from fluctuations in atmospheric temperature. We made every effort to maintain the length of the ECDL cavity, while evaluating oscillation-frequency stability. We used a Super-Invar board as the platform for our compact ECDL system to minimize the influence of thermal expansion, because of its low expansion coefficient. We then compared the effect of atmospheric temperature variations between two experimental conditions, with the Super-invar board and without it, and finally took note of the improvement in performance, using the board.

  5. Mesoscale cavities in hollow-core waveguides for quantum optics with atomic ensembles

    NASA Astrophysics Data System (ADS)

    Haapamaki, C. M.; Flannery, J.; Bappi, G.; Al Maruf, R.; Bhaskara, S. V.; Alshehri, O.; Yoon, T.; Bajcsy, M.

    2016-08-01

    Single-mode hollow-core waveguides loaded with atomic ensembles offer an excellent platform for light-matter interactions and nonlinear optics at low photon levels. We review and discuss possible approaches for incorporating mirrors, cavities, and Bragg gratings into these waveguides without obstructing their hollow cores. With these additional features controlling the light propagation in the hollow-core waveguides, one could potentially achieve optical nonlinearities controllable by single photons in systems with small footprints that can be integrated on a chip. We propose possible applications such as single-photon transistors and superradiant lasers that could be implemented in these enhanced hollow-core waveguides.

  6. Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity

    PubMed Central

    Saeed, A.; Panaro, S.; Zaccaria, R. Proietti; Raja, W.; Liberale, C.; Dipalo, M.; Messina, G. C.; Wang, H.; De Angelis, F.; Toma, A.

    2015-01-01

    The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding. PMID:26057661

  7. Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity

    NASA Astrophysics Data System (ADS)

    Saeed, A.; Panaro, S.; Zaccaria, R. Proietti; Raja, W.; Liberale, C.; Dipalo, M.; Messina, G. C.; Wang, H.; de Angelis, F.; Toma, A.

    2015-06-01

    The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding.

  8. Imaging of hard- and soft-tissue structure in the oral cavity by optical coherence tomography

    SciTech Connect

    Colston, Bill W.; Everett, Mathew J.; Da Silva, Luiz B. Otis, Linda L. Stroeve, Pieter Nathel, Howard

    1998-06-01

    We have developed a prototype optical coherent tomography (OCT) system for the imaging of hard and soft tissue in the oral cavity. High-resolution images of {ital in vitro} porcine periodontal tissues have been obtained with this system. The images clearly show the enamel{endash}cementum and the gingiva{endash}tooth interfaces, indicating OCT is a potentially useful technique for diagnosis of periodontal diseases. To our knowledge, this is the first application of OCT for imaging biologic hard tissue. {copyright} 1998 Optical Society of America

  9. All-optical diode structure based on asymmetrical coupling by a micro-cavity and FP cavity at two sides of photonic crystal waveguide

    SciTech Connect

    Liu, Bin Liu, Yun-Feng; He, Xing-Dao; Jia, Chen

    2016-06-15

    A high efficiency all-optical diode based on photonic crystal (PC) waveguide has been proposed and numerically investigated by finite-difference time-domain (FDTD) method. The structure is asymmetrically coupled by a micro-cavity containing nonlinear Kerr medium and a FP cavity at sides of PC waveguide. Because of interference between two cavities, Fano peak and FP peak can both appear in transmission spectra and unidirectional transmission can be achieved. The working wavelength can set between two peaks and near to the Fano peak. For forward launch with suitable light intensity, nonlinear Kerr effect of micro-cavity can been excited. It will result in red shift of Fano peak and achieving forward transmission. But for backward launch, a stronger incidence light is needed to the excite Kerr effect due to the design of asymmetric structure. This design has many advantages, including high maximum transmittance, high transmittance contrast ratio, low power threshold, short response time, and ease of integration.

  10. Electro-thermo-optical simulation of vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Smagley, Vladimir Anatolievich

    Three-dimensional electro-thermal simulator based on the double-layer approximation for the active region was coupled to optical gain and optical field numerical simulators to provide a self-consistent steady-state solution of VCSEL current-voltage and current-output power characteristics. Methodology of VCSEL modeling had been established and applied to model a standard 850-nm VCSEL based on GaAs-active region and a novel intracavity-contacted 400-nm GaN-based VCSEL. Results of GaAs VCSEL simulation were in a good agreement with experiment. Correlations between current injection and radiative mode profiles have been observed. Physical sub-models of transport, optical gain and cavity optical field were developed. Carrier transport through DBRs was studied. Problem of optical fields in VCSEL cavity was treated numerically by the effective frequency method. All the sub-models were connected through spatially inhomogeneous rate equation system. It was shown that the conventional uncoupled analysis of every separate physical phenomenon would be insufficient to describe VCSEL operation.

  11. Bridging the Gap between RF and Optical Patch Antenna Analysis via the Cavity Model

    PubMed Central

    Unal, G. S.; Aksun, M. I.

    2015-01-01

    Although optical antennas with a variety of shapes and for a variety of applications have been proposed and studied, they are still in their infancy compared to their radio frequency (rf) counterparts. Optical antennas have mainly utilized the geometrical attributes of rf antennas rather than the analysis tools that have been the source of intuition for antenna engineers in rf. This study intends to narrow the gap of experience and intuition in the design of optical patch antennas by introducing an easy-to-understand and easy-to-implement analysis tool in rf, namely, the cavity model, into the optical regime. The importance of this approach is not only its simplicity in understanding and implementation but also its applicability to a broad class of patch antennas and, more importantly, its ability to provide the intuition needed to predict the outcome without going through the trial-and-error simulations with no or little intuitive guidance by the user. PMID:26522889

  12. Bridging the Gap between RF and Optical Patch Antenna Analysis via the Cavity Model

    NASA Astrophysics Data System (ADS)

    Unal, G. S.; Aksun, M. I.

    2015-11-01

    Although optical antennas with a variety of shapes and for a variety of applications have been proposed and studied, they are still in their infancy compared to their radio frequency (rf) counterparts. Optical antennas have mainly utilized the geometrical attributes of rf antennas rather than the analysis tools that have been the source of intuition for antenna engineers in rf. This study intends to narrow the gap of experience and intuition in the design of optical patch antennas by introducing an easy-to-understand and easy-to-implement analysis tool in rf, namely, the cavity model, into the optical regime. The importance of this approach is not only its simplicity in understanding and implementation but also its applicability to a broad class of patch antennas and, more importantly, its ability to provide the intuition needed to predict the outcome without going through the trial-and-error simulations with no or little intuitive guidance by the user.

  13. Bridging the Gap between RF and Optical Patch Antenna Analysis via the Cavity Model.

    PubMed

    Unal, G S; Aksun, M I

    2015-11-02

    Although optical antennas with a variety of shapes and for a variety of applications have been proposed and studied, they are still in their infancy compared to their radio frequency (rf) counterparts. Optical antennas have mainly utilized the geometrical attributes of rf antennas rather than the analysis tools that have been the source of intuition for antenna engineers in rf. This study intends to narrow the gap of experience and intuition in the design of optical patch antennas by introducing an easy-to-understand and easy-to-implement analysis tool in rf, namely, the cavity model, into the optical regime. The importance of this approach is not only its simplicity in understanding and implementation but also its applicability to a broad class of patch antennas and, more importantly, its ability to provide the intuition needed to predict the outcome without going through the trial-and-error simulations with no or little intuitive guidance by the user.

  14. Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode.

    PubMed

    Verhagen, E; Deléglise, S; Weis, S; Schliesser, A; Kippenberg, T J

    2012-02-01

    Optical laser fields have been widely used to achieve quantum control over the motional and internal degrees of freedom of atoms and ions, molecules and atomic gases. A route to controlling the quantum states of macroscopic mechanical oscillators in a similar fashion is to exploit the parametric coupling between optical and mechanical degrees of freedom through radiation pressure in suitably engineered optical cavities. If the optomechanical coupling is 'quantum coherent'--that is, if the coherent coupling rate exceeds both the optical and the mechanical decoherence rate--quantum states are transferred from the optical field to the mechanical oscillator and vice versa. This transfer allows control of the mechanical oscillator state using the wide range of available quantum optical techniques. So far, however, quantum-coherent coupling of micromechanical oscillators has only been achieved using microwave fields at millikelvin temperatures. Optical experiments have not attained this regime owing to the large mechanical decoherence rates and the difficulty of overcoming optical dissipation. Here we achieve quantum-coherent coupling between optical photons and a micromechanical oscillator. Simultaneously, coupling to the cold photon bath cools the mechanical oscillator to an average occupancy of 1.7 ± 0.1 motional quanta. Excitation with weak classical light pulses reveals the exchange of energy between the optical light field and the micromechanical oscillator in the time domain at the level of less than one quantum on average. This optomechanical system establishes an efficient quantum interface between mechanical oscillators and optical photons, which can provide decoherence-free transport of quantum states through optical fibres. Our results offer a route towards the use of mechanical oscillators as quantum transducers or in microwave-to-optical quantum links.

  15. Monitoring tumor therapeutic response with diffuse optical spectroscopies

    NASA Astrophysics Data System (ADS)

    Sunar, Ulas

    The diffuse optical technique using Near-Infrared (NIR) light provides a promising means for non-invasive imaging and clinical diagnosis of deep tissues. During the last few years, we have developed a multi-modal diffuse optical technique combining two qualitatively different methodologies: Diffuse Reflectance Spectroscopy (DRS) and Diffuse Correlation Spectroscopy (DCS). This approach permits real-time, non-invasive and simultaneous quantification of tissue hemoglobin concentration, blood oxygen saturation and blood flow. The instrumentation is portable and rapid, and it has enabled us to study tissue responses in a variety of physiological contexts from cancer treatment monitoring to functional imaging of brain. In this thesis I focus on monitoring of tumor responses to therapies in preclinical and clinical contexts. In preclinical applications, I investigate an antivascular therapy in animal models. The effects of an antivascular drug, Combretastatin, were monitored continuously and were found to induce substantial reduction of blood flow and tissue oxygen. The observations of blood flow and oxygenation were then correlated with power Doppler Ultrasound and EF5 (hypoxia biomarker) techniques, respectively. In another animal model application, the chemotherapy drug, Onconase (Onc), was tested. Onc enhances the therapeutic effects of the drug Cisplatin, which is currently used as a chemotherapeutic agent for head and neck patients during chemoradiation therapy. Our observations demonstrated that Onc increased both tissue blood flow and tissue blood oxygenation; we also compared our results with those from MRI/MRS measurements. The diffuse optical technique was then translated to the clinic, i.e. head and neck patients during chemo-radiation therapy. Our pilot study with eight patients revealed significant early changes in hemodynamic parameters suggesting that daily optics-based therapy monitoring during the first two weeks of chemo-radiation therapy may have

  16. Primary diffuse large B-cell lymphoma of the oral cavity: germinal center classification.

    PubMed

    Bhattacharyya, Indraneel; Chehal, Hardeep K; Cohen, Donald M; Al-Quran, Samer Z

    2010-09-01

    Primary lymphomas of the oral cavity are rare and the most frequent type is diffuse large B-cell lymphoma (DLBCL). Recently, several reports have highlighted the value of classifying DLBCL into prognostically important subgroups, namely germinal center B-cell like (GCB) and non-germinal center B-cell like (non-GCB) lymphomas based on gene expression profiles and by immunohistochemical expression of CD10, BCL6 and MUM-1. GCB lymphomas tend to exhibit a better prognosis than non-GCB lymphomas. Studies validating this classification have been done for DLBCL of the breast, CNS, testes and GI tract. Therefore we undertook this study to examine if primary oral DLBCLs reflect this trend. We identified 13 cases (age range 38-91 years) from our archives dating from 2003-09. IHC was performed using antibodies against germinal center markers (CD10, BCL6), activated B-cell markers (MUM1, BCL2) and Ki-67 (proliferation marker). Cases were sub-classified as GCB subgroup if CD10 and/or BCL6 were positive and MUM-1, was negative and as non-GCB subgroup if CD10 was negative and MUM-1 was positive. Immunoreactivity was noted in 2/13 cases for CD10, in 12/13 for BCL6, in 8/13 for MUM-1, and in 6/13 for BCL2. Therefore, 8/13 (58%) were sub-classified as non-GCB DLBCLs and 5/13 (42%) as GCB subgroup. All tumors showed frequent labeling with Ki-67 (range 40-95%). Four of the 8 patients with non-GCB subgroup succumbed to their disease, with the mean survival rate of 16 months. Two patients in this group are alive, one with no evidence of disease and another with disease. No information was available for the other 3 patients in this group. Four of the 5 patients in the GCB subgroup were alive with no evidence of disease and one patient succumbed to complications of therapy and recurrent disease after 18 months. In conclusion, our analysis shows that primary oral DLBCL predominantly belongs to the non-GCB subgroup, which tends to exhibit a poorer prognosis. These findings could allow

  17. Optical gain from vertical Ge-on-Si resonant-cavity light emitting diodes with dual active regions

    NASA Astrophysics Data System (ADS)

    Lin, Guangyang; Wang, Jiaqi; Huang, Zhiwei; Mao, Yichen; Li, Cheng; Huang, Wei; Chen, Songyan; Lai, Hongkai; Huang, Shihao

    2017-09-01

    Vertical resonant-cavity light emitting diodes with dual active regions consisting of highly n-doped Ge/GeSi multiple quantum wells (MQWs) and a Ge epilayer are proposed to improve the light emitting efficiency. The MQWs are designed to optically pump the underlying Ge epilayer under electric injection. Abundant excess carriers can be optically pumped into the Γ valley of the Ge epilayer apart from electric pumping. With the combination of a vertical cavity, the efficiency of the optical-pumping process was effectively improved due to the elongation of the optical length in the cavity. With the unique feature, optical gain from the Ge epilayer is observed between 1625 and 1700 nm at injection current densities of >1.528 kA/cm2. The demonstration of optical gain from the Ge epilayer indicates that this strategy can be generally useful for Si-based light sources with indirect band materials.

  18. Aerosol optical properties measurement by recently developed cavity-enhanced aerosol single scattering albedometer

    NASA Astrophysics Data System (ADS)

    Zhao, Weixiong; Xu, Xuezhe; Zhang, Qilei; Fang, Bo; Qian, Xiaodong; Chen, Weidong; Gao, Xiaoming; Zhang, Weijun

    2015-04-01

    Development of appropriate and well-adapted measurement technologies for real-time in-situ measurement of aerosol optical properties is an important step towards a more accurate and quantitative understanding of aerosol impacts on climate and the environment. Aerosol single scattering albedo (SSA, ω), the ratio between the scattering (αscat) and extinction (αext) coefficients, is an important optical parameter that governs the relative strength of the aerosol scattering and absorption capacity. Since the aerosol extinction coefficient is the sum of the absorption and scattering coefficients, a commonly used method for the determination of SSA is to separately measure two of the three optical parameters - absorption, scattering and extinction coefficients - with different instruments. However, as this method involves still different instruments for separate measurements of extinction and absorption coefficients under different sampling conditions, it might cause potential errors in the determination of SSA value, because aerosol optical properties are very sensitive to the sampling conditions such as temperature and relative humidity (RH). In this paper, we report on the development of a cavity-enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) and an integrating sphere (IS) for direct in-situ measurement of aerosol scattering and extinction coefficients on the exact same sample volume. The cavity-enhanced albedometer holds great promise for high-sensitivity and high-precision measurement of ambient aerosol scattering and extinction coefficients (hence absorption coefficient and SSA determination) and for absorbing trace gas concentration. In addition, simultaneous measurements of aerosol scattering and extinction coefficients enable a potential application for the retrieval of particle number size distribution and for faster retrieval of aerosols' complex RI. The albedometer was deployed to

  19. Method of varying a characteristic of an optical vertical cavity structure formed by metalorganic vapor phase epitaxy

    DOEpatents

    Hou, Hong Q.; Coltrin, Michael E.; Choquette, Kent D.

    2001-01-01

    A process for forming an array of vertical cavity optical resonant structures wherein the structures in the array have different detection or emission wavelengths. The process uses selective area growth (SAG) in conjunction with annular masks of differing dimensions to control the thickness and chemical composition of the materials in the optical cavities in conjunction with a metalorganic vapor phase epitaxy (MOVPE) process to build these arrays.

  20. Strong atom-field coupling for Bose-Einstein condensates in an optical cavity on a chip.

    PubMed

    Colombe, Yves; Steinmetz, Tilo; Dubois, Guilhem; Linke, Felix; Hunger, David; Reichel, Jakob

    2007-11-08

    An optical cavity enhances the interaction between atoms and light, and the rate of coherent atom-photon coupling can be made larger than all decoherence rates of the system. For single atoms, this 'strong coupling regime' of cavity quantum electrodynamics has been the subject of many experimental advances. Efforts have been made to control the coupling rate by trapping the atom and cooling it towards the motional ground state; the latter has been achieved in one dimension so far. For systems of many atoms, the three-dimensional ground state of motion is routinely achieved in atomic Bose-Einstein condensates (BECs). Although experiments combining BECs and optical cavities have been reported recently, coupling BECs to cavities that are in the strong-coupling regime for single atoms has remained an elusive goal. Here we report such an experiment, made possible by combining a fibre-based cavity with atom-chip technology. This enables single-atom cavity quantum electrodynamics experiments with a simplified set-up and realizes the situation of many atoms in a cavity, each of which is identically and strongly coupled to the cavity mode. Moreover, the BEC can be positioned deterministically anywhere within the cavity and localized entirely within a single antinode of the standing-wave cavity field; we demonstrate that this gives rise to a controlled, tunable coupling rate. We study the heating rate caused by a cavity transmission measurement as a function of the coupling rate and find no measurable heating for strongly coupled BECs. The spectrum of the coupled atoms-cavity system, which we map out over a wide range of atom numbers and cavity-atom detunings, shows vacuum Rabi splittings exceeding 20 gigahertz, as well as an unpredicted additional splitting, which we attribute to the atomic hyperfine structure. We anticipate that the system will be suitable as a light-matter quantum interface for quantum information.

  1. Application of optical diffusion theory to transcutaneous bilirubinometry

    NASA Astrophysics Data System (ADS)

    Spott, Thorsten; Svaasand, Lars O.; Anderson, R. E.; Schmedling, P. F.

    1998-01-01

    Neonatal hyperbilirubinemia affects more than half of the newborns and represents a potentially serious condition due to the toxicity of bilirubin to the central nervous system. A precise non-invasive technique for the monitoring of bilirubin concentration is desirable for the treatment of icteric babies. Transcutaneous bilirubinometry based on optical reflectance spectra is complicated by the superposition of the spectral absorption properties of melanin and haemoglobin with those of bilirubin. Diffusion theory forms a suitable model for the description of light propagation in tissue. In this treatment, an inverse diffusion approach is developed to measure bilirubin concentration in tissue by means of the reflectance spectrum. First results of its application to in vivo measurements are encouraging.

  2. Real-time Optical Motion Correction for Diffusion Tensor Imaging

    PubMed Central

    Aksoy, Murat; Forman, Christoph; Straka, Matus; Skare, Stefan; Holdsworth, Samantha; Hornegger, Joachim; Bammer, Roland

    2011-01-01

    Head motion is a fundamental problem in brain MRI. The problem is further compounded in diffusion tensor imaging (DTI) because of long acquisition times, and the sensitivity of the tensor computation to even small misregistration. To combat motion artifacts in DTI, a novel real-time prospective motion correction method was introduced using an in-bore monovision system. The system consists of a camera mounted on the head coil and a self-encoded checkerboard marker that is attached to the patient’s forehead. Our experiments showed that optical prospective motion correction is more effective at removing motion artifacts compared to image-based retrospective motion correction. Statistical analysis revealed a significant improvement in similarity between diffusion data acquired at different time points when prospective correction was used compared to retrospective correction (p<0.001). PMID:21432898

  3. Pre-seizure state identified by diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Zhou, Junli; Jiang, Ruixin; Yang, Hao; Carney, Paul R.; Jiang, Huabei

    2014-01-01

    In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a ``pre-seizure'' state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.

  4. Pre-seizure state identified by diffuse optical tomography

    PubMed Central

    Zhang, Tao; Zhou, Junli; Jiang, Ruixin; Yang, Hao; Carney, Paul R.; Jiang, Huabei

    2014-01-01

    In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a “pre-seizure” state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways. PMID:24445927

  5. Characterization of tissue optical properties for prostate PDT using interstitial diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Liang, Xing; Wang, Ken Kang-hsin; Zhu, Timothy C.

    2012-02-01

    Photodynamic therapy (PDT) is an important treatment modality for localized diseases such as prostate cancer. In prostate PDT, light distribution is an important factor because it is directly related to treatment efficacy. During PDT, light distribution is determined by tissue optical property distributions (or heterogeneity). In this study, an interstitial diffuse optical tomography (iDOT) method was used to characterize optical properties in tissues. Optical properties (absorption and reduced scattering coefficients) of the prostate gland were reconstructed by solving the inverse problem using an adjoint model based on diffusion equation using a modified matlab public user code NIRFAST. In the modified NIRFAST method, linear sources were modeled for the reconstruction. Cross talking between absorption coefficients and reduced scattering coefficients were studied to have minimal effect, and a constrained optical property method (set either absorption coefficient or reduced scattering coefficient to be homogeneous) is also studied. A prostate phantom with optical anomalies was used to verify the iDOT method. The reconstructed results were compared with the known optical properties, and the spatial distribution of optical properties for this phantom was successfully reconstructed.

  6. The effect of nonadiabaticity on the efficiency of quantum memory based on an optical cavity

    NASA Astrophysics Data System (ADS)

    Veselkova, N. G.; Sokolov, I. V.

    2017-07-01

    Quantum efficiency is an important characteristic of quantum memory devices that are aimed at recording the quantum state of light signals and its storing and reading. In the case of memory based on an ensemble of cold atoms placed in an optical cavity, the efficiency is restricted, in particular, by relaxation processes in the system of active atomic levels. We show how the effect of the relaxation on the quantum efficiency can be determined in a regime of the memory usage in which the evolution of signals in time is not arbitrarily slow on the scale of the field lifetime in the cavity and when the frequently used approximation of the adiabatic elimination of the quantized cavity mode field cannot be applied. Taking into account the effect of the nonadiabaticity on the memory quality is of interest in view of the fact that, in order to increase the field-medium coupling parameter, a higher cavity quality factor is required, whereas storing and processing of sequences of many signals in the memory implies that their duration is reduced. We consider the applicability of the well-known efficiency estimates via the system cooperativity parameter and estimate a more general form. In connection with the theoretical description of the memory of the given type, we also discuss qualitative differences in the behavior of a random source introduced into the Heisenberg-Langevin equations for atomic variables in the cases of a large and a small number of atoms.

  7. Feasibility of fiber optic displacement sensor scanning system for imaging of dental cavity

    NASA Astrophysics Data System (ADS)

    Rahman, Husna Abdul; Che Ani, Adi Izhar; Harun, Sulaiman Wadi; Yasin, Moh.; Apsari, Retna; Ahmad, Harith

    2012-07-01

    The purpose of this study is to investigate the potential of intensity modulated fiber optic displacement sensor scanning system for the imaging of dental cavity. Here, we discuss our preliminary results in the imaging of cavities on various teeth surfaces, as well as measurement of the diameter of the cavities which are represented by drilled holes on the teeth surfaces. Based on the analysis of displacement measurement, the sensitivities and linear range for the molar, canine, hybrid composite resin, and acrylic surfaces are obtained at 0.09667 mV/mm and 0.45 mm 0.775 mV/mm and 0.4 mm 0.5109 mV/mm and 0.5 mm and 0.25 mV/mm and 0.5 mm, respectively, with a good linearity of more than 99%. The results also show a clear distinction between the cavity and surrounding tooth region. The stability, simplicity of design, and low cost of fabrication make it suitable for restorative dentistry.

  8. Photon bunching and anti-bunching with two dipole-coupled atoms in an optical cavity

    NASA Astrophysics Data System (ADS)

    Zheng, Ya-Mei; Hu, Chang-Sheng; Yang, Zhen-Biao; Wu, Huai-Zhi

    2016-10-01

    We investigate the effect of the dipole-dipole interaction (DDI) on the photon statistics with two atoms trapped in an optical cavity driven by a laser field and subjected to cooperative emission. By means of the quantum trajectory analysis and the second-order correlation functions, we show that the photon statistics of the cavity transmission can be flexibly modulated by the DDI while the incoming coherent laser selectively excites the atom-cavity system’s nonlinear Jaynes-Cummings ladder of excited states. Finally, we find that the effect of the cooperatively atomic emission can also be revealed by the numerical simulations and can be explained with a simplified picture. The DDI induced nonlinearity gives rise to highly nonclassical photon emission from the cavity that is significant for quantum information processing and quantum communication. Project supported by the National Natural Science Foundation of China (Grant Nos. 11305037, 11347114, and 11374054) and the Natural Science Foundation of Fujian Province, China (Grant No. 2013J01012).

  9. Measurement of epithelial thickness within the oral cavity using optical coherence tomography (OCT)

    NASA Astrophysics Data System (ADS)

    Prestin, S.; Betz, C.; Kraft, M.

    2010-02-01

    Optical coherence tomography (OCT) is a promising method in the early diagnosis of oral cavity cancer. The objective of the present study is to determine normal values of epithelial thickness in the oral cavity, as no such data are to be found in the literature. In healthy test persons, epithelial thickness of the oral mucosa was determined with the help of OCT separately for each side at nine different locations. Special attention was directed to those sites having the highest incidence for the development of dysplasias and carcinomas. Depending on the location within the oral cavity, the epithelium demonstrated a varying thickness. The highest values were found in the region of the tongue and the cheek, whereas the floor of the mouth showed the thinnest epithelium. Our data serve as reference values for detecting oral malignancy and determining the approximate grade of dysplasia. In this circumstance, a differentiated view of the different regions is important due to the variation in thickness of the epithelium within the normal oral cavity.

  10. Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

    SciTech Connect

    Khandekar, Chinmay; Rodriguez, Alejandro W.; Lin, Zin

    2015-04-13

    We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.

  11. Solar tower cavity receiver aperture optimization based on transient optical and thermo-hydraulic modeling

    NASA Astrophysics Data System (ADS)

    Schöttl, Peter; Bern, Gregor; van Rooyen, De Wet; Heimsath, Anna; Fluri, Thomas; Nitz, Peter

    2017-06-01

    A transient simulation methodology for cavity receivers for Solar Tower Central Receiver Systems with molten salt as heat transfer fluid is described. Absorbed solar radiation is modeled with ray tracing and a sky discretization approach to reduce computational effort. Solar radiation re-distribution in the cavity as well as thermal radiation exchange are modeled based on view factors, which are also calculated with ray tracing. An analytical approach is used to represent convective heat transfer in the cavity. Heat transfer fluid flow is simulated with a discrete tube model, where the boundary conditions at the outer tube surface mainly depend on inputs from the previously mentioned modeling aspects. A specific focus is put on the integration of optical and thermo-hydraulic models. Furthermore, aiming point and control strategies are described, which are used during the transient performance assessment. Eventually, the developed simulation methodology is used for the optimization of the aperture opening size of a PS10-like reference scenario with cavity receiver and heliostat field. The objective function is based on the cumulative gain of one representative day. Results include optimized aperture opening size, transient receiver characteristics and benefits of the implemented aiming point strategy compared to a single aiming point approach. Future work will include annual simulations, cost assessment and optimization of a larger range of receiver parameters.

  12. Bose–Einstein condensation versus Dicke–Hepp–Lieb transition in an optical cavity

    SciTech Connect

    Piazza, Francesco; Strack, Philipp; Zwerger, Wilhelm

    2013-12-15

    We provide an exact solution for the interplay between Bose–Einstein condensation and the Dicke–Hepp–Lieb self-organization transition of an ideal Bose gas trapped inside a single-mode optical cavity and subject to a transverse laser drive. Based on an effective action approach, we determine the full phase diagram at arbitrary temperature, which features a bi-critical point where the transitions cross. We calculate the dynamically generated band structure of the atoms and the associated suppression of the critical temperature for Bose–Einstein condensation in the phase with a spontaneous periodic density modulation. Moreover, we determine the evolution of the polariton spectrum due to the coupling of the cavity photons and the atomic field near the self-organization transition, which is quite different above or below the Bose–Einstein condensation temperature. At low temperatures, the critical value of the Dicke–Hepp–Lieb transition decreases with temperature and thus thermal fluctuations can enhance the tendency to a periodic arrangement of the atoms. -- Highlights: •Atoms inside a driven cavity can undergo two transitions: self-organization and BEC. •The phase diagram has four phases which coexist at a bi-critical point. •Atom–cavity coupling creates a dynamical lattice for the atoms. •Finite temperature can enhance the tendency towards self-organization. •We calculate the detailed spectrum of the polaritonic excitations.

  13. Pulsed semiconductor lasers with higher optical strength of cavity output mirrors

    SciTech Connect

    Petrunov, A. N.; Podoskin, A. A.; Shashkin, I. S.; Slipchenko, S. O.; Pikhtin, N. A. Nalet, T. A.; Fetisova, N. V.; Vavilova, L. S.; Lyutetskiy, A. V.; Alekseev, P. A.; Titkov, A. N.; Tarasov, I. S.

    2010-06-15

    Asymmetric heterostructures with an ultrathick waveguide based on an AlGaAs/GaAs alloy system that allow lasing at a wavelength of 905 nm have been developed and fabricated by hydride metalorganic vapor-phase epitaxy. The internal optical loss and internal quantum efficiency of semiconductor lasers based on such structures were 0.7 cm{sup -1} and 97%, respectively. It is shown that the highest output optical power of laser diodes with antireflecting (SiO{sub 2}) and reflecting (Si/SiO{sub 2}) coatings deposited on untreated Fabry-Perot cavity facets obtained by cleaving in an oxygen atmosphere reached 67 W in the pulsed mode and is limited by mirror damage. Treatment of Fabry-Perot cavity facets by etching in argon plasma and the formation of coatings with passivating and oxygen-blocking GaN and Si{sub 3}N{sub 4} layers allowed an increase in the maximum output optical power to 120 W. Mirror damage was not observed at the attained output optical power.

  14. Multi-spectral terahertz sensing: proposal for a coupled-cavity quantum cascade laser based optical feedback interferometer.

    PubMed

    Qi, Xiaoqiong; Agnew, Gary; Kundu, Iman; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Dean, Paul; Grier, Andrew; Valavanis, Alexander; Linfield, Edmund H; Giles Davies, A; Indjin, Dragan; Rakić, Aleksandar D

    2017-05-01

    We propose a laser feedback interferometer operating at multiple terahertz (THz) frequency bands by using a pulsed coupled-cavity THz quantum cascade laser (QCL) under optical feedback. A theoretical model that contains multi-mode reduced rate equations and thermal equations is presented, which captures the interplay between electro-optical, thermal, and feedback effects. By using the self-heating effect in both active and passive cavities, self-mixing signal responses at three different THz frequency bands are predicted. A multi-spectral laser feedback interferometry system based on such a coupled-cavity THz QCL will permit ultra-high-speed sensing and spectroscopic applications including material identification.

  15. Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

    PubMed

    Hippler, Michael

    2015-08-04

    We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

  16. Four-wave mixing and optical phase conjugation in vertical-cavity surface-emitting devices

    NASA Astrophysics Data System (ADS)

    Vansuch, Gregory Joseph

    1997-08-01

    Four-wave mixing (FWM), a nonlinear optical process, was investigated in resonant cavity light emitting diodes (RCLEDs) and vertical cavity surface emitting lasers (VCSELs) below lasing threshold. These semiconductor photonic devices consisted of an optical gain region of quantum wells sandwiched between two distributed Bragg reflector (DBR) mirrors. Pump and probe lasers were injected into the devices to generate FWM. The dependence of FWM on bias current, pump laser power, and spectral and spatial separation between pump and probe lasers was investigated experimentally. A computer model of FWM based on the wave and carrier density equations was developed and agreed well with experimental results. Conjugate reflectivities of 1.0 were obtained in the VCSEL when bias current was below threshold but above transparency. Reasonable conjugate reflectivities were obtained for pump-probe detunings up to 2 GHz in both devices. Noncollinear FWM was performed for the first time in VCSELs or RCLEDs at angles up to 10o. Both experiment and model showed the possibility of generating a strong reflected conjugate signal while minimizing the reflected pump signal. The noncollinear FWM demonstrated the possibility of phase front conjugation for correcting aberrated signals in vertical cavity devices.

  17. Hybridization of plasmonic antenna and cavity modes: Extreme optics of nanoparticle-on-mirror nanogaps

    NASA Astrophysics Data System (ADS)

    Tserkezis, C.; Esteban, R.; Sigle, D. O.; Mertens, J.; Herrmann, L. O.; Baumberg, J. J.; Aizpurua, J.

    2015-11-01

    The precise structural details of metallic nanogaps within optical antennae are found to dramatically modify the plasmonic response, producing a complex pattern of electromagnetic modes that can be directly observed in scattering experiments. We analyze this situation theoretically in the nanoparticle-on-mirror construct, which forms a plasmonic nanogap sensitive to even atomic-scale restructuring of nanoparticle morphology. We focus on the effect of nanoparticle faceting, which allows the formation of ultrathin cavities between the particle and the underlying metallic film in the nanoparticle-on-mirror geometry. Two different sets of modes are identified: longitudinal antenna modes, which are strongly radiative and excited for all facet width ranges, and transverse cavity modes produced at large facets and exhibiting extreme confinement. The interaction and hybridization of antenna and cavity modes is determined by their symmetry and the precise morphology of the nanogap edges. Understanding such complex optics from nanoparticle-on-mirror structures is important to elucidate a wide variety of emerging photochemical and optoelectronic processes.

  18. Optical feedback cavity enhanced absorption spectroscopy: effective adjustment of the feedback-phase

    NASA Astrophysics Data System (ADS)

    Habig, J. C.; Nadolny, J.; Meinen, J.; Saathoff, H.; Leisner, T.

    2012-02-01

    Optical-feedback cavity enhanced absorption spectroscopy (OF-CEAS) is a very sensitive technique for the detection of trace amounts of gaseous absorbers. The most crucial parameter in an OF-CEAS setup is the optical phase of the light fed back into the laser source, which is usually controlled by the position of a piezo driven mirror. Various approaches for the analysis of the cavity transmitted light with respect to feedback-phase are presented, and tested on simulated phase and frequency dependent cavity transmission. Finally, we present the performance of a digital signal processor based regulator—employing one of these approaches—in a real OF-CEAS experiment. The results of the simulation show that several algorithms are well suited for the task of control signal generation. They confirm also that with the presented approach, a mode by mode correction of the feedback-phase is possible. Consequently, a regulatory bandwidth of 37 Hz was achieved. This maximum control frequency was limited by the piezo system.

  19. Nonlinear optical effects and Hong-Ou-Mandel interference in cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Mirza, Imran M.; van Enk, Steven J.

    Pure quantum interference among single photons is one of the key ingredients to perform linear optics quantum computation (LOQC). The Hong-Ou-Mandel interference (HOMI) [C. K. Hong, Z. Y. Ou and L. Mandel, Phys. Rev. Lett. 59, (18), 2044-2046 (1987)] i.e. complete destructive interference between two identical and indistinguishable photons simultaneously entering input ports of a 50/50 beam splitter, is a well-known example in this context. In this talk, I'll present our theoretical study of HOMI in a coupled Jaynes-Cummings array. In particular and by applying quantum jump/trajectory formalism, I'll focus on how partial quantum interference between two photons survive both non-linearities produced by two-level emitter and spectral filtering due to optical cavities in our coupled cavity array setup [Imran M. Mirza and Steven J. van Enk, Opt. Comm. 343, 172-177 (2015)]. Along with LOQC, this work is crucial from the perspective of exploiting coupled cavity arrays to store single photons reliably (without altering their temporal and spectral traits) [Imran M. Mirza, Steven J. van Enk and Jeff Kimble, JOSA B, 10, 2640-2649, (2013)].

  20. T-shaped cavity dual-frequency Nd:YAG laser with electro-optical modulation

    NASA Astrophysics Data System (ADS)

    Xing, Junhong; Jiao, Mingxing; Liu, Yun

    2016-05-01

    A T-shaped cavity dual-frequency Nd:YAG laser with electro-optical modulation is proposed, which consists of both p- and s-cavities sharing the same gain medium of Nd:YAG. Each cavity was not only able to select longitudinal mode but also tune frequency using an electro-optic birefringent filter polarization beam splitter + lithium niobate. The frequency difference of dual frequency was tuned through the whole gain bandwidth of Nd:YAG, which is far above the usually accepted free spectral range value in the case of a single-axis laser. As a result, the simultaneous operation of orthogonally and linearly polarized dual-frequency laser was obtained, which coincides with the theoretical analysis based on Jones matrices. The obtained frequency difference ranges from 0 to 132 GHz. This offers a simple and widely tunable source with potential for portable frequency reference applications in terahertz-wave generation and absolute-distance interferometry measurement areas.

  1. TOPICAL REVIEW: Recent advances in diffuse optical imaging

    NASA Astrophysics Data System (ADS)

    Gibson, A. P.; Hebden, J. C.; Arridge, S. R.

    2005-02-01

    We review the current state-of-the-art of diffuse optical imaging, which is an emerging technique for functional imaging of biological tissue. It involves generating images using measurements of visible or near-infrared light scattered across large (greater than several centimetres) thicknesses of tissue. We discuss recent advances in experimental methods and instrumentation, and examine new theoretical techniques applied to modelling and image reconstruction. We review recent work on in vivo applications including imaging the breast and brain, and examine future challenges.

  2. Mapping the human brain at rest with diffuse optical tomography

    PubMed Central

    White, Brian R.; Snyder, Abraham Z.; Cohen, Alexander L.; Petersen, Steven E.; Raichle, Marcus E.; Schlaggar, Bradley L.; Culver, Joseph P.

    2014-01-01

    Diffuse optical tomography (DOT) is a portable functional neuroimaging technique that is able to simultaneously measure both oxy- and deoxyhemoglobin responses to brain activity. Herein, we demonstrate a technique for mapping functional connections in the brain by measuring the spatial distribution of temporal correlations in resting brain activity. Simultaneous DOT imaging over the motor and visual cortices yielded robust correlation maps reproducing the expected functional neural architecture. These functional connectivity methods will have utility in certain populations, such as those who are unconscious or very young, who have difficulty performing the behaviors required in traditional task-based functional neuroimaging paradigms. PMID:19964102

  3. Diffuse optical imaging using spatially and temporally modulated light

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Thomas D.; Cerussi, Albert E.; Cuccia, David J.; Tromberg, Bruce J.

    2012-07-01

    The authors describe the development of diffuse optical imaging (DOI) technologies, specifically the use of spatial and temporal modulation to control near infrared light propagation in thick tissues. We present theory and methods of DOI focusing on model-based techniques for quantitative, in vivo measurements of endogenous tissue absorption and scattering properties. We specifically emphasize the common conceptual framework of the scalar photon density wave for both temporal and spatial frequency-domain approaches. After presenting the history, theoretical foundation, and instrumentation related to these methods, we provide a brief review of clinical and preclinical applications from our research as well as our outlook on the future of DOI technology.

  4. Reflectance Diffuse Optical Tomography: Its Application to Human Brain Mapping

    NASA Astrophysics Data System (ADS)

    Ueda, Yukio; Yamanaka, Takeshi; Yamashita, Daisuke; Suzuki, Toshihiko; Ohmae, Etsuko; Oda, Motoki; Yamashita, Yutaka

    2005-09-01

    We report the successful application of reflectance diffuse optical tomography (DOT) using near-infrared light with the new reconstruction algorithm that we developed to the observation of regional hemodynamic changes in the brain under specific mental tasks. Our results reveal the heterogeneous distribution of oxyhemoglobin and deoxyhemoglobin in the brain, showing complementary images of oxyhemoglobin and deoxyhemoglobin changes in certain regions. We conclude that our reflectance DOT has practical potential for human brain mapping, as well as in the diagnostic imaging of brain diseases.

  5. Estimation of kinetic model parameters in fluorescence optical diffusion tomography.

    PubMed

    Milstein, Adam B; Webb, Kevin J; Bouman, Charles A

    2005-07-01

    We present a technique for reconstructing the spatially dependent dynamics of a fluorescent contrast agent in turbid media. The dynamic behavior is described by linear and nonlinear parameters of a compartmental model or some other model with a deterministic functional form. The method extends our previous work in fluorescence optical diffusion tomography by parametrically reconstructing the time-dependent fluorescent yield. The reconstruction uses a Bayesian framework and parametric iterative coordinate descent optimization, which is closely related to Gauss-Seidel methods. We demonstrate the method with a simulation study.

  6. Diffuse optical tomography based on time-resolved compressive sensing

    NASA Astrophysics Data System (ADS)

    Farina, A.; Betcke, M.; Di Sieno, L.; Bassi, A.; Ducros, N.; Pifferi, A.; Valentini, G.; Arridge, S.; D'Andrea, C.

    2017-02-01

    Diffuse Optical Tomography (DOT) can be described as a highly multidimensional problem generating a huge data set with long acquisition/computational times. Biological tissue behaves as a low pass filter in the spatial frequency domain, hence compressive sensing approaches, based on both patterned illumination and detection, are useful to reduce the data set while preserving the information content. In this work, a multiple-view time-domain compressed sensing DOT system is presented and experimentally validated on non-planar tissue-mimicking phantoms containing absorbing inclusions.

  7. Diffuse optical tomography to investigate the newborn brain.

    PubMed

    Lee, Chuen Wai; Cooper, Robert J; Austin, Topun

    2017-09-01

    Over the past 15 years, functional near-infrared spectroscopy (fNIRS) has emerged as a powerful technology for studying the developing brain. Diffuse optical tomography (DOT) is an extension of fNIRS that combines hemodynamic information from dense optical sensor arrays over a wide field of view. Using image reconstruction techniques, DOT can provide images of the hemodynamic correlates to neural function that are comparable to those produced by functional magnetic resonance imaging. This review article explains the principles of DOT, and highlights the growing literature on the use of DOT in the study of healthy development of the infant brain, and the study of novel pathophysiology in infants with brain injury. Current challenges, particularly around instrumentation and image reconstruction, will be discussed, as will the future of this growing field, with particular focus on whole-brain, time-resolved DOT.

  8. Recipes to make organic phantoms for diffusive optical spectroscopy.

    PubMed

    Quarto, Giovanna; Pifferi, Antonio; Bargigia, Ilaria; Farina, Andrea; Cubeddu, Rinaldo; Taroni, Paola

    2013-04-10

    Three recipes are presented to make tissue constituent-equivalent phantoms of water and lipids. Different approaches to prepare the emulsion are proposed. Nature phantoms are made using no emulsifying agent, but just a professional disperser; instead Agar and Triton phantoms are made using agar or Triton X-100, respectively, as agents to emulsify water and lipids. Different water-to-lipid ratios ranging from 30% to 70% by mass were tested. A broadband time-resolved diffuse optical spectroscopy system was used to characterize the phantoms in terms of optical properties and composition. For some water/lipid ratios the emulsion fails or the phantom has limited lifetime, but in most cases the recipes provide phantoms with a high degree of homogeneity [coefficient of variation (CV) of 4.6% and 1.5% for the absorption and reduced scattering coefficient, respectively] and good reproducibility (CV of 8.3% and 12.4% for absorption and reduced scattering coefficient, respectively).

  9. Broadband diffuse optical characterization of elastin for biomedical applications.

    PubMed

    Konugolu Venkata Sekar, Sanathana; Beh, Joo Sin; Farina, Andrea; Dalla Mora, Alberto; Pifferi, Antonio; Taroni, Paola

    2017-10-01

    Elastin is a key structural protein of dynamic connective tissues widely found in the extracellular matrix of skin, arteries, lungs and ligaments. It is responsible for a range of diseases related to aging of biological tissues. The optical characterization of elastin can open new opportunities for its investigation in biomedical studies. In this work, we present the absorption spectra of elastin using a broadband (550-1350nm) diffuse optical spectrometer. Distortions caused by fluorescence and finite bandwidth of the laser source on estimated absorption were effectively accounted for in measurements and data analysis and compensated. A comprehensive summary and comparison between collagen and elastin is presented, highlighting distinct features for its accurate quantification in biological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Split operator method for fluorescence diffuse optical tomography using anisotropic diffusion regularisation with prior anatomical information

    PubMed Central

    Correia, Teresa; Aguirre, Juan; Sisniega, Alejandro; Chamorro-Servent, Judit; Abascal, Juan; Vaquero, Juan J.; Desco, Manuel; Kolehmainen, Ville; Arridge, Simon

    2011-01-01

    Fluorescence diffuse optical tomography (fDOT) is an imaging modality that provides images of the fluorochrome distribution within the object of study. The image reconstruction problem is ill-posed and highly underdetermined and, therefore, regularisation techniques need to be used. In this paper we use a nonlinear anisotropic diffusion regularisation term that incorporates anatomical prior information. We introduce a split operator method that reduces the nonlinear inverse problem to two simpler problems, allowing fast and efficient solution of the fDOT problem. We tested our method using simulated, phantom and ex-vivo mouse data, and found that it provides reconstructions with better spatial localisation and size of fluorochrome inclusions than using the standard Tikhonov penalty term. PMID:22091447

  11. Scanning, non-contact, hybrid broadband diffuse optical spectroscopy and diffuse correlation spectroscopy system

    PubMed Central

    Johansson, Johannes D.; Mireles, Miguel; Morales-Dalmau, Jordi; Farzam, Parisa; Martínez-Lozano, Mar; Casanovas, Oriol; Durduran, Turgut

    2016-01-01

    A scanning system for small animal imaging using non-contact, hybrid broadband diffuse optical spectroscopy (ncDOS) and diffuse correlation spectroscopy (ncDCS) is presented. The ncDOS uses a two-dimensional spectrophotometer retrieving broadband (610-900 nm) spectral information from up to fifty-seven source-detector distances between 2 and 5 mm. The ncDCS data is simultaneously acquired from four source-detector pairs. The sample is scanned in two dimensions while tracking variations in height. The system has been validated with liquid phantoms, demonstrated in vivo on a human fingertip during an arm cuff occlusion and on a group of mice with xenoimplanted renal cell carcinoma. PMID:26977357

  12. Cavity-enhanced optical Hall effect in two-dimensional free charge carrier gases detected at terahertz frequencies.

    PubMed

    Knight, S; Schöche, S; Darakchieva, V; Kühne, P; Carlin, J-F; Grandjean, N; Herzinger, C M; Schubert, M; Hofmann, T

    2015-06-15

    The effect of a tunable, externally coupled Fabry-Perot cavity to resonantly enhance the optical Hall effect signatures at terahertz frequencies produced by a traditional Drude-like two-dimensional electron gas is shown and discussed in this Letter. As a result, the detection of optical Hall effect signatures at conveniently obtainable magnetic fields, for example, by neodymium permanent magnets, is demonstrated. An AlInN/GaN-based high-electron mobility transistor structure grown on a sapphire substrate is used for the experiment. The optical Hall effect signatures and their dispersions, which are governed by the frequency and the reflectance minima and maxima of the externally coupled Fabry-Perot cavity, are presented and discussed. Tuning the externally coupled Fabry-Perot cavity strongly modifies the optical Hall effect signatures, which provides a new degree of freedom for optical Hall effect experiments in addition to frequency, angle of incidence, and magnetic field direction and strength.

  13. Diffused holographic information storage and retrieval using photorefractive optical materials

    NASA Astrophysics Data System (ADS)

    McMillen, Deanna Kay

    Holography offers a tremendous opportunity for dense information storage, theoretically one bit per cubic wavelength of material volume, with rapid retrieval, of up to thousands of pages of information simultaneously. However, many factors prevent the theoretical storage limit from being reached, including dynamic range problems and imperfections in recording materials. This research explores new ways of moving closer to practical holographic information storage and retrieval by altering the recording materials, in this case, photorefractive crystals, and by increasing the current storage capacity while improving the information retrieved. As an experimental example of the techniques developed, the information retrieved is the correlation peak from an optical recognition architecture, but the materials and methods developed are applicable to many other holographic information storage systems. Optical correlators can potentially solve any signal or image recognition problem. Military surveillance, fingerprint identification for law enforcement or employee identification, and video games are but a few examples of applications. A major obstacle keeping optical correlators from being universally accepted is the lack of a high quality, thick (high capacity) holographic recording material that operates with red or infrared wavelengths which are available from inexpensive diode lasers. This research addresses the problems from two positions: find a better material for use with diode lasers, and reduce the requirements placed on the material while maintaining an efficient and effective system. This research found that the solutions are new dopants introduced into photorefractive lithium niobate to improve wavelength sensitivities and the use of a novel inexpensive diffuser that reduces the dynamic range and optical element quality requirements (which reduces the cost) while improving performance. A uniquely doped set of 12 lithium niobate crystals was specified and

  14. Optical Oscillation Established Using Acousto-Optic Bragg Angle Defraction In Conjunction With Closed Cavity Feedback

    NASA Astrophysics Data System (ADS)

    Vezzoli, G. C.; Cadwallender, W.; Megargel, L. R.; Mentzer, M. A.; Craley, D. E.

    1987-03-01

    An optical oscillator has been designed, constructed, and operated by using a HeNe laser and acousto-optic modulator in conjunction with two opposed fiber optic feedback circuits. Depending on round-trip feedback time, a low frequency ( 1Hz) sinusoidal oscillator or a high frequency (100KHz) square wave (,..%,1 us rise time) is obtained.

  15. Dynamics of a low-threshold optically pumped organic vertical-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Shayesteh, Mohammad Reza; Darvish, Ghafar

    2016-06-01

    We propose a low-threshold optically pumped organic vertical-cavity surface-emitting laser (OVCSEL). This device has the capability to apply both electrical and optical excitation. The microcavity structure consists of an organic light emitting diode with field-effect electron transport inserted in a high-quality factor double distributed Bragg reflector. The simulated quality factor of the microcavity is shown to be as high as 16,000. Also, we investigate threshold behaviour and the dynamics of the optically pumped OVCSEL with sub-picosecond pulses. Results from numerical simulation show that lasing threshold is 12.8 pJ/0.64 µJ cm-2 when pumped by sub-picosecond pulses of λ = 400 nm wavelength light.

  16. Quantum simulation of 2D topological physics in a 1D array of optical cavities.

    PubMed

    Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

    2015-07-06

    Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration.

  17. Quantum simulation of 2D topological physics in a 1D array of optical cavities

    PubMed Central

    Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

    2015-01-01

    Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration. PMID:26145177

  18. Strong coupling between chlorosomes of photosynthetic bacteria and a confined optical cavity mode.

    PubMed

    Coles, David M; Yang, Yanshen; Wang, Yaya; Grant, Richard T; Taylor, Robert A; Saikin, Semion K; Aspuru-Guzik, Alán; Lidzey, David G; Tang, Joseph Kuo-Hsiang; Smith, Jason M

    2014-11-28

    Strong exciton-photon coupling is the result of a reversible exchange of energy between an excited state and a confined optical field. This results in the formation of polariton states that have energies different from the exciton and photon. We demonstrate strong exciton-photon coupling between light-harvesting complexes and a confined optical mode within a metallic optical microcavity. The energetic anti-crossing between the exciton and photon dispersions characteristic of strong coupling is observed in reflectivity and transmission with a Rabi splitting energy on the order of 150 meV, which corresponds to about 1,000 chlorosomes coherently coupled to the cavity mode. We believe that the strong coupling regime presents an opportunity to modify the energy transfer pathways within photosynthetic organisms without modification of the molecular structure.

  19. High-Q silicon photonic crystal cavity for enhanced optical nonlinearities

    SciTech Connect

    Dharanipathy, Ulagalandha Perumal; Tonin, Mario; Houdré, Romuald; Minkov, Momchil Savona, Vincenzo

    2014-09-08

    We fabricate and experimentally characterize an H0 photonic crystal slab nanocavity with a design optimized for maximal quality factor, Q = 1.7 × 10{sup 6}. The cavity, fabricated from a silicon slab, has a resonant mode at λ = 1.59 μm and a measured Q-factor of 400 000. It displays nonlinear effects, including high-contrast optical bistability, at a threshold power among the lowest ever reported for a silicon device. With a theoretical modal volume as small as V = 0.34(λ/n){sup 3}, this cavity ranks among those with the highest Q/V ratios ever demonstrated, while having a small footprint suited for integration in photonic circuits.

  20. Design and analysis of photonic crystal micro-cavity based optical sensor platform

    SciTech Connect

    Goyal, Amit Kumar Dutta, Hemant Sankar Pal, Suchandan

    2016-04-13

    In this paper, the design of a two-dimensional photonic crystal micro-cavity based integrated-optic sensor platform is proposed. The behaviour of designed cavity is analyzed using two-dimensional Finite Difference Time Domain (FDTD) method. The structure is designed by deliberately inserting some defects in a photonic crystal waveguide structure. Proposed structure shows a quality factor (Q) of about 1e5 and the average sensitivity of 500nm/RIU in the wavelength range of 1450 – 1580 nm. Sensing technique is based on the detection of shift in upper-edge cut-off wavelength for a reference signal strength of –10 dB in accordance with the change in refractive index of analyte.

  1. Tunable Optical Performances on a Periodic Array of Plasmonic Bowtie Nanoantennas with Hollow Cavities

    NASA Astrophysics Data System (ADS)

    Chou Chau, Yuan-Fong; Chou Chao, Chung-Ting; Rao, Jhin-Yu; Chiang, Hai-Pang; Lim, Chee Ming; Lim, Ren Chong; Voo, Nyuk Yoong

    2016-09-01

    We propose a design method to tune the near-field intensities and absorption spectra of a periodic array of plasmonic bowtie nanoantennas (PBNAs) by introducing the hollow cavities inside the metal nanostructures. The numerical method is performed by finite element method that demonstrates the engineered hollow PBNAs can tune the optical spectrum in the range of 400-3000 nm. Simulation results show the hollow number is a key factor for enhancing the cavity plasmon resonance with respect to the hotspot region in PBNAs. The design efforts primarily concentrate on shifting the operation wavelength and enhancing the local fields by manipulating the filling dielectric medium, outline film thickness, and hollow number in PBNAs. Such characteristics indicate that the proposed hollow PBNAs can be a potential candidate for plasmonic enhancers and absorbers in multifunctional opto-electronic biosensors.

  2. Tuning all-Optical Analog to Electromagnetically Induced Transparency in nanobeam cavities using nanoelectromechanical system

    PubMed Central

    Shi, Peng; Zhou, Guangya; deng, Jie; Tian, Feng; Chau, Fook Siong

    2015-01-01

    We report the observations of all-optical electromagnetically induced transparency in nanostructures using waveguide side-coupled with photonic crystal nanobeam cavities, which has measured linewidths much narrower than individual resonances. The quality factor of transparency resonance can be 30 times larger than those of measured individual resonances. When the gap between cavity and waveguide is reduced to 10 nm, the bandwidth of destructive interference region can reach 10 nm while the width of transparency resonance is 0.3 nm. Subsequently, a comb-drive actuator is introduced to tune the line shape of the transparency resonance. The width of the peak is reduced to 15 pm and the resulting quality factor exceeds 105. PMID:26415907

  3. Electro-optically cavity-dumped 3  ns Tm:LuAG laser.

    PubMed

    Zhang, Ye; Yao, Baoquan; Dai, Tongyu; Shi, Hongwei; Han, Liu; Shen, Yingjie; Ju, Youlun

    2016-04-10

    It is reported in this paper that a cavity-dumped electro-optically Q-switched Tm:LuAG oscillator offers a unique combination of high power, constant short pulse duration, and high repetition rate at a wavelength of 2012.7 nm. The constant short pulse durations of 3 ns were achieved by the cavity-dumped technology at different repetition rates from 60 to 100 kHz. An average power of 1.22 W and a peak power of 4.1 kW were obtained at a repetition rate of 100 kHz and an incident pump power of 42.3 W, corresponding to the slope efficiency of 6% and beam quality factor of M2∼1.4. In addition, the accumulation time of intracavity photons from 500 to 1000 ns was studied for the performance of the output characteristic.

  4. A tunable optical cavity for an x-ray free-electron laser oscillator.

    SciTech Connect

    Kim, K.-J.; Shvyd'ko, Y.

    2009-03-01

    An x-ray free-electron laser oscillator proposed recently for hard x rays [K. Kim, Y. Shvydko, and S. Reiche, Phys. Rev. Lett. 100, 244802 (2008)] can be made tunable by using an x-ray cavity composed of four crystals, instead of two. The tunability of x-ray energy will significantly enhance the usefulness of an x-ray free-electron laser oscillator. We present a detailed analysis of the four-crystal optical cavity and choice of crystals for several applications: inelastic x-ray scattering, nuclear resonant scattering, bulk-sensitive hard x-ray photoemission spectroscopy, other high-energy-resolution ({le} 1 meV) spectroscopic probes, and for imaging with hard x rays at near-atomic resolution ({approx} 1 nm).

  5. Tuning all-Optical Analog to Electromagnetically Induced Transparency in nanobeam cavities using nanoelectromechanical system.

    PubMed

    Shi, Peng; Zhou, Guangya; Deng, Jie; Tian, Feng; Chau, Fook Siong

    2015-09-29

    We report the observations of all-optical electromagnetically induced transparency in nanostructures using waveguide side-coupled with photonic crystal nanobeam cavities, which has measured linewidths much narrower than individual resonances. The quality factor of transparency resonance can be 30 times larger than those of measured individual resonances. When the gap between cavity and waveguide is reduced to 10 nm, the bandwidth of destructive interference region can reach 10 nm while the width of transparency resonance is 0.3 nm. Subsequently, a comb-drive actuator is introduced to tune the line shape of the transparency resonance. The width of the peak is reduced to 15 pm and the resulting quality factor exceeds 10(5).

  6. Developing High-Density Diffuse Optical Tomography for Neuroimaging

    NASA Astrophysics Data System (ADS)

    White, Brian Richard

    Clinicians who care for brain-injured patients and premature infants desire a bedside monitor of brain function. A decade ago, there was hope that optical imaging would be able to fill this role, as it combined fMRI's ability to construct cortical maps with EEG's portable, cap-based systems. However, early optical systems had poor imaging performance, and the momentum for the technique slowed. In our lab, we develop diffuse optical tomography (DOT), which is a more advanced method of performing optical imaging. My research has been to pioneer the in vivo use of DOT for advanced neuroimaging by (1) quantifying the advantages of DOT through both in silico simulation and in vivo performance metrics, (2) restoring confidence in the technique with the first retinotopic mapping of the visual cortex (a benchmark for fMRI and PET), and (3) creating concepts and methods for the clinical translation of DOT. Hospitalized patients are unable to perform complicated neurological tasks, which has motivated us to develop the first DOT methods for resting-state brain mapping with functional connectivity. Finally, in collaboration with neonatologists, I have extended these methods with proof-of-principle imaging of brain-injured premature infants. This work establishes DOT's improvements in imaging performance and readies it for multiple clinical and research roles.

  7. Influence of radiation on double conjugate diffusion in a porous cavity

    SciTech Connect

    Azeem,; Idris, Mohd Yamani Idna; Khan, T. M. Yunus; Badruddin, Irfan Anjum Nik-Ghazali, N.

    2016-05-06

    The current work highlights the effect of radiation on the conjugate heat and mass transfer in a square porous cavity having a solid wall. The solid wall is placed at the center of cavity. The left surface of cavity is maintained at higher temperature T{sub w} and concentration C{sub w} whereas the right surface is maintained at T{sub c} and C{sub c} such that T{sub w}>T{sub c} and Cw>Cc. The top and bottom surfaces are adiabatic. The governing equations are solved with the help of finite element method by making use of triangular elements. The results are discussed with respect to two different heights of solid wall inside the porous medium along with the radiation parameter.

  8. Influence of radiation on double conjugate diffusion in a porous cavity

    NASA Astrophysics Data System (ADS)

    Azeem, Khan, T. M. Yunus; Badruddin, Irfan Anjum; Nik-Ghazali, N.; Idris, Mohd Yamani Idna

    2016-05-01

    The current work highlights the effect of radiation on the conjugate heat and mass transfer in a square porous cavity having a solid wall. The solid wall is placed at the center of cavity. The left surface of cavity is maintained at higher temperature Tw and concentration Cw whereas the right surface is maintained at Tc and Cc such that Tw>Tc and Cw>Cc. The top and bottom surfaces are adiabatic. The governing equations are solved with the help of finite element method by making use of triangular elements. The results are discussed with respect to two different heights of solid wall inside the porous medium along with the radiation parameter.

  9. Super-diffusion in optical realizations of Anderson localization

    NASA Astrophysics Data System (ADS)

    Krivolapov, Yevgeny; Levi, Liad; Fishman, Shmuel; Segev, Mordechai; Wilkinson, Michael

    2012-04-01

    We discuss the dynamics of particles in one dimension in potentials that are random in both space and time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is suppressed by random fluctuations in the refractive index. If the refractive index fluctuates along the direction of the paraxial propagation of the beam, the localization is destroyed. We analyze this broken localization in terms of the spectral decomposition of the potential. When the potential has a discrete spectrum, the spread is controlled by the overlap of Chirikov resonances in phase space. As the number of Fourier components is increased, the resonances merge into a continuum, which is described by a Fokker-Planck equation. We express the diffusion coefficient in terms of the spectral intensity of the potential. For a general class of potentials that are commonly used in optics, the solutions to the Fokker-Planck equation exhibit anomalous diffusion in phase space, implying that when Anderson localization is broken by temporal fluctuations of the potential, the result is transport at a rate similar to a ballistic one or even faster. For a class of potentials which arise in some existing realizations of Anderson localization, atypical behavior is found.

  10. Bulk diffusive relaxation mechanisms in optically excited topological insulators

    NASA Astrophysics Data System (ADS)

    Sterzi, A.; Manzoni, G.; Sbuelz, L.; Cilento, F.; Zacchigna, M.; Bugnon, Ph.; Magrez, A.; Berger, H.; Crepaldi, A.; Parmigiani, F.

    2017-03-01

    The possibility to inject spin currents in topological insulators (TIs) by ultrashort optical pulses has stimulated intense studies of their out-of-equilibrium electronic properties. However, a comprehensive description of the electronic relaxation dynamics has been elusive, so far. In order to reveal the role of the bulk and surface states in the microscopic scattering mechanisms, we have investigated, by means of time- and angle-resolved photoemission spectroscopy, a wide set of TIs. These have been selected in order to display different positions of the Fermi energy (EF) within the bulk band structure. When three-dimensional bulk states lie at EF, we observe a fast relaxation dynamics with a characteristic time scale of a few picoseconds (ps). On the contrary, a long lasting excited state is recorded when only the two-dimensional surface state crosses EF. These findings suggest the important role played by spatial diffusion in the direction orthogonal to the surface in governing the relaxation mechanisms. We propose that this electron diffusive mechanism is driven by the optically induced temperature gradient that is at play only for electrons residing in bulk states.

  11. Spectralon diffusers used as in-flight optical calibration hardware

    NASA Astrophysics Data System (ADS)

    Chommeloux, Beatrice; Baudin, Gilles; Gourmelon, Georges; Bezy, Jean-Loup; van Eijk-Olij, Carina; Schaarsberg, Jos G.; Werij, Henri G.; Zoutman, Erik

    1998-10-01

    The medium resolution imaging spectrometer (MERIS), developed under European Space Agency (ESA) contract, for the Envisat 1 Polar Orbit Earth Mission belongs to a new generation of Ocean Color sensors which aim to improve the knowledge of some crucial processes of our planet. The instrument currently in the final stages of development is built by an international team led by AEROSPATIALE under ENVISAT prime contractor-ship of DORNIER. MERIS is a 'pushbroom' type instrument which measures the radiance of the Earth in 15 programmable spectral bands between 390 nm and 1040 nm over a 1150 km swath width. During the duration of the MERIS mission, radiometric in-flight calibration sequences are carried on a regular basis by the observation of Spectralon diffusers illuminated by the sun. The high accuracy required over the 4 years mission duration necessitates the precise knowledge of the calibration reference and the stability of the reference over the mission has to be controlled. This presentation details the influence of cleaning procedures on optical stability of the Spectralon flat plate diffusers calibration reference under space conditions and sun illumination. This paper will also define the BRDF characterization performances achieved with the Flight Model flat plate diffusers following implementation of the selected cleaning procedure.

  12. Detection of early seizures by diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Hajihashemi, M. Reza; Zhou, Junli; Carney, Paul R.; Jiang, Huabei

    2015-03-01

    In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Besides, preclinical seizure experiments need to be conducted in awake animals with images reconstructed and displayed in real-time. We demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking brain activities with high spatiotemporal resolution. We developed methods to conduct seizure experiments in fully awake rats using a subject-specific helmet and a restraining mechanism. For the first time, we detected early hemodynamic responses with heterogeneous patterns several minutes preceding the electroencephalographic seizure onset, supporting the presence of a "pre-seizure" state both in anesthetized and awake rats. Using a novel time-series analysis of scattering images, we show that the analysis of scattered diffuse light is a sensitive and reliable modality for detecting changes in neural activity associated with generalized seizure. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.

  13. Optical Phased Array Antennas using Coupled Vertical Cavity Surface Emitting Lasers

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; Rojas, Roberto A.; Nessel, James A.; Miranda, Felix A.

    2007-01-01

    High data rate communication links are needed to meet the needs of NASA as well as other organizations to develop space-based optical communication systems. These systems must be robust to high radiation environments, reliable, and operate over a wide temperature range. Highly desirable features include beam steering capability, reconfigurability, low power consumption, and small aperture size. Optical communication links, using coupled vertical cavity surface emitting laser radiating elements are promising candidates for the transmit portion of these communication links. In this talk we describe a mission scenario, and how the antenna requirements are derived from the mission needs. We describe a potential architecture for this type of antenna, and outline the advantages and drawbacks of this approach relative to competing technologies. The technology we are proposing used coupled arrays of 1550 nm vertical cavity surface emitting lasers for transmission. The feasibility of coupling these arrays together, to form coherent high-power beams that can be modulated at data rates exceeding 1 Gbps, will be explored. We will propose an architecture that enables electronic beam steering, thus mitigating the need for ancillary acquisition, tracking and beam pointing equipment such as needed for current optical communicatin systems. The beam-steering capability we are proposing also opens the possibility of using this technology for inter-satellite communicatin links, and satellite-to-surface links.

  14. Region-of-interest diffuse optical tomography system

    SciTech Connect

    Saikia, Manob Jyoti; Kanhirodan, Rajan

    2016-01-15

    Diffuse optical tomography (DOT) using near-infrared light is a promising tool for non-invasive imaging of deep tissue. This technique is capable of quantitative reconstruction of absorption (μ{sub a}) and scattering coefficient (μ{sub s}) inhomogeneities in the tissue. The rationale for reconstructing the optical property map is that the absorption coefficient variation provides diagnostic information about metabolic and disease states of the tissue. The aim of DOT is to reconstruct the internal tissue cross section with good spatial resolution and contrast from noisy measurements non-invasively. We develop a region-of-interest scanning system based on DOT principles. Modulated light is injected into the phantom/tissue through one of the four light emitting diode sources. The light traversing through the tissue gets partially absorbed and scattered multiple times. The intensity and phase of the exiting light are measured using a set of photodetectors. The light transport through a tissue is diffusive in nature and is modeled using radiative transfer equation. However, a simplified model based on diffusion equation (DE) can be used if the system satisfies following conditions: (a) the optical parameter of the inhomogeneity is close to the optical property of the background, and (b) μ{sub s} of the medium is much greater than μ{sub a} (μ{sub s} > > μ{sub a}). The light transport through a highly scattering tissue satisfies both of these conditions. A discrete version of DE based on finite element method is used for solving the inverse problem. The depth of probing light inside the tissue depends on the wavelength of light, absorption, and scattering coefficients of the medium and the separation between the source and detector locations. Extensive simulation studies have been carried out and the results are validated using two sets of experimental measurements. The utility of the system can be further improved by using multiple wavelength light sources. In such

  15. Quantum Popov robust stability analysis of an optical cavity containing a saturated Kerr medium

    NASA Astrophysics Data System (ADS)

    Petersen, Ian R.

    2017-09-01

    This paper applies results of the robust stability of nonlinear quantum systems to a system consisting of an optical cavity containing a saturated Kerr medium. The system is characterised by a Hamiltonian operator that contains a non-quadratic term involving a quartic function of the annihilation and creation operators. A saturated version of the Kerr nonlinearity leads to a sector-bounded nonlinearity that enables a quantum small gain theorem to be applied to this system in order to analyse its stability. Also, a non-quadratic version of a quantum Popov stability criterion is presented and applied to analyse the stability of this system.

  16. Study of the interference effects in an optical cavity for organic light-emitting diode applications.

    PubMed

    Villani, Fulvia; Grimaldi, Immacolata Angelica; Nenna, Giuseppe; Del Mauro, Anna De Girolamo; Loffredo, Fausta; Minarini, Carla

    2010-10-15

    The interference effects generated in a bottom-emitting electroluminescent device fabricated on a polymer underlayer introduced with the aim of improving the anode roughness have been studied. The analysis of the interference fringes at different detection angles and the spatial coherence demonstrates that this phenomenon is due to multiple internal reflections that propagate in the polymer layer. This effect can be eliminated by modifying the polymer thickness and the incidence angle of the electromagnetic radiation at the anode-polymer interface. Inkjet etching technology is adopted for microcavities-shaped polymer structuring to destroy the resonator effect of the optical cavity.

  17. External-cavity diode lasers with different devices and collimating optics.

    PubMed

    Kane, D M; Willis, A P

    1995-07-20

    Comparative operating characteristics of external-cavity diode lasers (ECDL's) with either a channel substrate planar device or a multi-quantum-well (MQW) device are presented. These include the output beam profile, which is significantly altered depending on the collimating lens used (either multielement or graded index), power versus injection-current characteristics, and the optical frequency and the rf spectra. The coherence lengths of the different laser diode-collimating-lens combinations in the ECDL are measured, and a new method for calculating the coupling coefficient and the coupled values of the internal quantum efficiency and the internal lumped loss is demonstrated for the MQW device.

  18. Tunable semiconductor laser with an acousto-optic filter in an external fibre cavity

    SciTech Connect

    Andreeva, E V; Mamedov, D S; Ruenkov, A A; Shramenko, M V; Magdich, L N; Yakubovich, S D

    2006-04-30

    A tunable semiconductor laser with a laser amplifier based on a double-pass superluminescent diode as an active element and an acousto-optic filter in an external fibre cavity as a selective element is investigated. A continuous spectral tuning is achieved in a band of width 60 nm centered at a wavelength of 845 nm and the 'instant' linewidth below 0.05 nm is obtained. The sweep frequency within the tuning range achieves 200 Hz. The cw power at the output of a single-mode fibre was automatically maintained constant at the level up to 1.5 mW. (lasers and amplifiers)

  19. Optical switching of cross intensity correlation in cavity electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Rao, Shi; Hu, Xiangming; Xu, Jun; Li, Lingchao

    2017-03-01

    We present optical switching of cross intensity correlation in the context of cavity electromagnetically induced transparency configuration. For symmetrical parameters, the cross intensity correlation switches from negative to positive as the atom–pump detunings change symmetrically from one case to the other. In terms of the dressed atomic states and the Bogoliubov modes we analyze the atom–photon interaction mechanism for the switching behavior, and present a numerical verification. As a by-product, we show noise squeezing of the sum or difference intensity in a limited region of parameters.

  20. Short cavity active mode locking fiber laser for optical sensing and imaging

    NASA Astrophysics Data System (ADS)

    Lee, Hwi Don; Han, Ga Hee; Jeong, Syung Won; Jeong, Myung Yung; Kim, Chang-Seok; Shin, Jun Geun; Lee, Byeong Ha; Eom, Tae Joong

    2014-05-01

    We demonstrate a highly linear wavenumber- swept active mode locking (AML) fiber laser for optical sensing and imaging without any wavenumber-space resampling process. In this all-electric AML wavenumber-swept mechanism, a conventional wavelength selection filter is eliminated and, instead, the suitable programmed electric modulation signal is directly applied to the gain medium. Various types of wavenumber (or wavelength) tunings can be implemented because of the filter-less cavity configuration. Therefore, we successfully demonstrate a linearly wavenumber-swept AML fiber laser with 26.5 mW of output power to obtain an in-vivo OCT image at the 100 kHz swept rate.

  1. Half-period Aharonov-Bohm oscillations in disordered rotating optical ring cavities

    NASA Astrophysics Data System (ADS)

    Li, Huanan; Kottos, Tsampikos; Shapiro, Boris

    2016-09-01

    There exists an analogy between Maxwell equations in a rotating frame and the Schrödinger equation for a charged particle in the presence of a magnetic field. We exploit this analogy to point out that electromagnetic phenomena in the rotating frame, under appropriate conditions, can exhibit periodicity with respect to the angular velocity of rotation. In particular, in disordered ring cavities one finds the optical analog of the Al'tshuler-Aronov-Spivak effect well known in mesoscopic physics of disordered metals.

  2. Spectral engineering by flexible tunings of optical Tamm states and Fabry-Perot cavity resonance.

    PubMed

    Zhang, Xu-Lin; Song, Jun-Feng; Feng, Jing; Sun, Hong-Bo

    2013-11-01

    We present a design for spectral engineering in a metal dual distributed Bragg reflector (DBR)-based structure. Optical Tamm states and Fabry-Perot cavity mode, dual windows for light-matter interaction enhancement, can be excited simultaneously and tuned flexibly, including their respective bandwidth and resonant wavelength, due to the variable reflection phase from the outer DBR's internal surface. The design can find applications in solar cells for light trappings. Via calculations of overall absorptivity, the proposed simpler dual-states-based scheme is demonstrated to be almost as effective as the coherent-light-trapping scheme, owing to the dual-states-induced broader-band absorption enhancement.

  3. Uncertainty analysis of optical components absorption coefficient measurement using an intra-cavity device

    NASA Astrophysics Data System (ADS)

    Yan, Baozhu; Liu, Wenguang; Zhou, Qiong; Du, Shaojun; Yang, Yi

    2017-06-01

    In order to measure the absorption coefficient and performance degradation characteristics of optical components which used in high power laser system, an intra-cavity device was established based on a discharge-drived CW chemical laser. Two pieces of 45 degree reflecting mirrors were tested. Each mirror was tested for more than twenty times, and high power laser irradiation on the testing mirrors lasted 100 seconds continuously in each test. The dependence of absorption coefficients on irradiation times was acquired. The testing results of both reflecting mirrors showed that, the differences between the experimental absorption coefficients and their fitting curve were up to 30.7% and 21.6% respectively, and the differences were independent of irradiation condition, such as irradiation energy, irradiation power and beam crosssectional area. The uncertainty of absorption coefficient was composed of two parts. For one thing, the uncertainty of the direct measurement results, such as the temperature rise of optical components, can cause the uncertainty of absorption coefficients. This part of uncertainty was about 11.3%. For another, the resonant cavity need to be adjusted again when other optical components were replaced, which lead to the change of the incident angle of the optical components to be measured. A typical film system of 24 layers (12 pairs) was calculated by Thin Film Design Software called TFCalc, which showed the absorption coefficients increased with the increase of incident angle. When the angle of incidence was 0.5 degree from the design value, there would be -60 71ppm difference of absorption coefficient from the original one, and the uncertainty was 14.5%. When there was a deviation of 1 degree, the difference of absorption coefficient and the uncertainty were -112 155ppm and 31.7% respectively. This results showed that, the deviation of incident angle was between 0.5 1 degree in the test. In order to reduce the testing uncertainty of absorption

  4. Acousto-optical interaction of surface acoustic and optical waves in a two-dimensional phoxonic crystal hetero-structure cavity.

    PubMed

    Ma, Tian-Xue; Zou, Kui; Wang, Yue-Sheng; Zhang, Chuanzeng; Su, Xiao-Xing

    2014-11-17

    Phoxonic crystal is a promising material for manipulating sound and light simultaneously. In this paper, we theoretically demonstrate the propagation of acoustic and optical waves along the truncated surface of a two-dimensional square-latticed phoxonic crystal. Further, a phoxonic crystal hetero-structure cavity is proposed, which can simultaneously confine surface acoustic and optical waves. The interface motion and photoelastic effects are taken into account in the acousto-optical coupling. The results show obvious shifts in eigenfrequencies of the photonic cavity modes induced by different phononic cavity modes. The symmetry of the phononic cavity modes plays a more important role in the single-phonon exchange process than in the case of the multi-phonon exchange. Under the same deformation, the frequency shift of the photonic transverse electric mode is larger than that of the transverse magnetic mode.

  5. Controlling frontal photopolymerization with optical attenuation and mass diffusion

    NASA Astrophysics Data System (ADS)

    Hennessy, Matthew G.; Vitale, Alessandra; Matar, Omar K.; Cabral, João T.

    2015-06-01

    Frontal photopolymerization (FPP) is a versatile directional solidification process that can be used to rapidly fabricate polymer network materials by selectively exposing a photosensitive monomer bath to light. A characteristic feature of FPP is that the monomer-to-polymer conversion profiles take on the form of traveling waves that propagate into the unpolymerized bulk from the illuminated surface. Practical implementations of FPP require detailed knowledge about the conversion profile and speed of these traveling waves. The purpose of this theoretical study is to (i) determine the conditions under which FPP occurs and (ii) explore how optical attenuation and mass transport can be used to finely tune the conversion profile and propagation kinetics. Our findings quantify the strong optical attenuation and slow mass transport relative to the rate of polymerization required for FPP. The shape of the traveling wave is primarily controlled by the magnitude of the optical attenuation coefficients of the neat and polymerized material. Unexpectedly, we find that mass diffusion can increase the net extent of polymerization and accelerate the growth of the solid network. The theoretical predictions are found to be in excellent agreement with experimental data acquired for representative systems.

  6. CT guided diffuse optical tomography for breast cancer imaging

    NASA Astrophysics Data System (ADS)

    Baikejiang, Reheman; Zhang, Wei; Zhu, Dianwen; Li, Changqing

    2016-03-01

    Diffuse optical tomography (DOT) has attracted attentions in the last two decades due to its intrinsic sensitivity in imaging chromophores of tissues such as blood, water, and lipid. However, DOT has not been clinically accepted yet due to its low spatial resolution caused by strong optical scattering in tissues. Structural guidance provided by an anatomical imaging modality enhances the DOT imaging substantially. Here, we propose a computed tomography (CT) guided multispectral DOT imaging system for breast cancer detection. To validate its feasibility, we have built a prototype DOT imaging system which consists of a laser at wavelengths of 650 and an electron multiplying charge coupled device (EMCCD) camera. We have validated the CT guided DOT reconstruction algorithms with numerical simulations and phantom experiments, in which different imaging setup parameters, such as projection number of measurements, the width of measurement patch, have been investigated. Our results indicate that an EMCCD camera with air cooling is good enough for the transmission mode DOT imaging. We have also found that measurements at six projections are sufficient for DOT to reconstruct the optical targets with 4 times absorption contrast when the CT guidance is applied. Finally, we report our effort and progress on the integration of the multispectral DOT imaging system into a breast CT scanner.

  7. New spherical optical cavities with non-degenerated whispering gallery modes

    NASA Astrophysics Data System (ADS)

    Kumagai, Tsutaru; Palma, Giuseppe; Prudenzano, Francesco; Kishi, Tetsuo; Yano, Tetsuji

    2017-02-01

    New spherical resonators with internal defects are introduced to show anomalous whispering gallery modes (WGMs). The defect induces a symmetry breaking spherical cavity and splits the WGMs. A couple of defects, a hollow sphere (bubble), and a hollow ring, have been studied. The hollow sphere was fabricated and the splitting of WGM was observed. In this paper, this "non-degenerated WGMs (non-DWGMs) resonance" in a microsphere with hollow defect structure is reviewed based on our research. The resonance of WGMs in a sphere is identified by three integer parameters: the angular mode number, l, azimuthal mode number m, and radial mode number, n. The placement of the defect such as a hollow ring or single bubble is shown to break symmetry and resolve the degeneracy concerning m. This induces a variety of resonant wavelengths of the spherical cavity. A couple of simulations using the eigenmode and transient analyses propose how the placed defects affect the WGM resonance in the spherical cavity. For the sphere with a single bubble defect, the experimentally observed resonances in Nd-doped tellurite glass microsphere with a single bubble are clarified to be due to the splitting of resonance modes, i.e., the existence of "non-DWGMs" in the sphere. The defect bubble plays a role of opening the optically wide gate to introduce excitation light for Nd3+ pumping using non-DWGMs in the sphere efficiently.

  8. Numerical studies of the fluid and optical fields associated with complex cavity flows

    NASA Technical Reports Server (NTRS)

    Atwood, Christopher A.

    1992-01-01

    Numerical solutions for the flowfield about several cavity configurations have been computed using the Reynolds averaged Navier-Stokes equations. Comparisons between numerical and experimental results are made in two dimensions for free shear layers and a rectangular cavity, and in three dimensions for the transonic aero-window problem of the Stratospheric Observatory for Infrared Astronomy (SOFIA). Results show that dominant acoustic frequencies and magnitudes of the self excited resonant cavity flows compare well with the experiment. In addition, solution sensitivity to artificial dissipation and grid resolution levels are determined. Optical path distortion due to the flow field is modelled geometrically and is found to match the experiment. The fluid field was computed using a diagonalized scheme within an overset mesh framework. An existing code, OVERFLOW, was utilized with the additions of characteristic boundary condition and output routines required for reduction of the unsteady data. The newly developed code is directly applicable to a generalized three dimensional structured grid zone. Details are provided in a paper included in Appendix A.

  9. NO_2 Trace Measurements by Optical-Feedback Cavity-Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ventrillard-Courtillot, I.; Desbois, Th.; Foldes, T.; Romanini, D.

    2009-06-01

    In order to reach the sub-ppb NO_2 detection level required for environmental applications in remote areas, we develop a spectrometer based on a technique introduced a few years ago, named Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) [1]. It allows very sensitive and selective measurements, together with the realization of compact and robust set-ups as was subsequently demonstrated during measurements campaigns in harsh environments [2]. OF-CEAS benefits from the optical feedback to efficiently inject a cw-laser in a V-shaped high finesse cavity (typically 10 000). Cavity-enhanced absorption spectra are acquired on a small spectral region (˜1 cm^{-1}) that enables selective and quantitative measurements at a fast acquisition rate with a detection limit of several 10^{-10} cm^{-1} as reported in this work. Spectra are obtained with high spectral definition (150 MHz highly precisely spaced data points) and are self calibrated by cavity rind-down measurements regularly performed (typically every second). NO_2 measurements are performed with a commercial extended cavity diode laser around 411 nm, spectral region where intense electronic transitions occur. We will describe the set-up developed for in-situ measurements allowing real time concentration measurements at typically 5 Hz; and then report on the measurements performed with calibrated NO_2 reference samples to evaluate the linearity of the apparatus. The minimum detectable absorption loss is estimated by considering the standard deviation of the residual of one spectrum. We achieved 2x10^{-10} cm^{-1} for a single spectrum recorded in less than 100 ms at 100 mbar. It leads to a potential detection limit of 3x10^8 molecules/cm^3, corresponding to about 150 pptv at this pressure. [1] J. Morville, S. Kassi, M. Chenevier, and D. Romanini, Appl. Phys. B, 80, 1027 (2005). [2] D. Romanini, M. Chenevrier, S. Kassi, M. Schmidt, C. Valant, M. Ramonet, J. Lopez, and H.-J. Jost, Appl. Phys. B, 83, 659

  10. Disorder and dephasing as control knobs for light transport in optical fiber cavity networks

    NASA Astrophysics Data System (ADS)

    Viciani, Silvia; Gherardini, Stefano; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2016-11-01

    Transport phenomena represent a very interdisciplinary topic with applications in many fields of science, such as physics, chemistry, and biology. In this context, the possibility to design a perfectly controllable experimental setup, where to tune and optimize its dynamics parameters, is a challenging but very relevant task to emulate, for instance, the transmission of energy in light harvesting processes. Here, we experimentally build a scalable and controllable transport emulator based on optical fiber cavity networks where the system noise parameters can be finely tuned while maximizing the transfer efficiency. In particular, we demonstrate that disorder and dephasing noise are two control knobs allowing one to play with constructive and destructive interference to optimize the transport paths towards an exit site. These optical setups, on one side, mimic the transport dynamics in natural photosynthetic organisms and, on the other, are very promising platforms to artificially design optimal nanoscale structures for novel, more efficient, clean energy technologies.

  11. Transverse mode tailoring in diode lasers based on coupled large optical cavities

    NASA Astrophysics Data System (ADS)

    Gordeev, N. Yu; Maximov, M. V.; E Zhukov, A.

    2017-08-01

    The key principles of transverse mode engineering in edge-emitting lasers with broadened waveguides based on coupled large optical cavity (CLOC) structures are presented. The CLOC laser design is shown to be an effective approach for reducing the optical loss, broadening the waveguide, and lowering the beam divergence. Having simulated the sensitivity of the CLOC design to variations in layer thicknesses and compositions we have shown its high robustness. Advanced versions of the CLOC laser structures having two extra passive waveguides have been treated and shown to effectively eliminate several transverse modes. We have considered an application of the CLOC concept for waveguides with shifted active regions aimed at reducing laser thermal and electric resistances.

  12. Optimal feedback in efficient ring double-cavity optical parametric oscillators

    SciTech Connect

    Petnikova, V M; Shuvalov, Vladimir V

    2010-09-10

    It is shown that the use of two feedback circuits with matched transfer constants and optimal phase incursions in a nondegenerate optical parametric oscillator (OPO) makes it possible to localise the extremes of intensity distributions of interacting waves on the output face of a nonlinear crystal, which provides maximum possible conversion efficiency of pump energy. The optimisation procedure in this case is rather flexible because it is reduced to ambiguous matching of the period and shift of the extremes of exact analytic solutions of the corresponding problem in the form of cnoidal waves with respect to the nonlinear crystal position. Unlike the single-cavity OPO scheme, both these parameters can substantially exceed the nonlinear crystal length and even tend to infinity, which corresponds to solitary soliton-like solutions. (optical parametric oscillators)

  13. Observation of Noise-Assisted Transport in an All-Optical Cavity-Based Network

    NASA Astrophysics Data System (ADS)

    Viciani, Silvia; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2015-08-01

    Recent theoretical and experimental efforts have shown the remarkable and counterintuitive role of noise in enhancing the transport efficiency of complex systems. Here, we realize simple, scalable, and controllable optical fiber cavity networks that allow us to analyze the performance of transport networks for different conditions of interference, dephasing, and disorder. In particular, we experimentally demonstrate that the transport efficiency reaches a maximum when varying the external dephasing noise, i.e., a bell-like shape behavior that had been predicted only theoretically. These optical platforms are very promising simulators of quantum transport phenomena and could be used, in particular, to design and test optimal topologies of artificial light-harvesting structures for future solar energy technologies.

  14. Dynamic optical sampling by cavity tuning and its application in lidar.

    PubMed

    Yang, Lin; Nie, Jinsong; Duan, Lingze

    2013-02-11

    Optical sampling by cavity tuning (OSCAT) enables cost-effective realization of fast tunable optical delay using a single femtosecond laser. We report here a dynamic model of OSCAT, taking into account the continuous modulation of laser repetition rates. This allows us to evaluate the delay scan depth under high interferometer imbalance and high scan rates, which cannot be described by the previous static model. We also report the demonstration of remote motion tracking based on fast OSCAT. Target vibration as small as 15 µm peak to peak and as fast as 50 Hz along line-of-sight has been successfully detected at an equivalent free-space distance of more than 2 km.

  15. Plasmonic crystal cavity on single-mode optical fiber end facet for label-free biosensing

    NASA Astrophysics Data System (ADS)

    He, Xiaolong; Yi, Hui; Long, Jing; Zhou, Xin; Yang, Jie; Yang, Tian

    2016-06-01

    Surface plasmon resonance (SPR) devices on single-mode optical fiber (SMF) end facets are desired for label-free biosensing, due to flexible light delivery, in vivo inspection capability, and seamless integration with fiber-optic communication techniques. We report a plasmonic crystal cavity structure that has a steep resonance near the plasmonic bandedge, a fabrication process to efficiently transfer and align the structure onto a bare SMF end facet, and characterization of its sensing performance. With a sensitivity of 571 nm RIU-1, a figure of merit of 68 RIU-1 and a real-time refractive index detection limit of 3.5 × 10-6 RIU, our sensors can be readily applied in common SPR biosensing experiments. They are over an order of magnitude more sensitive than reported modified-end multimode fiber SPR devices, while there are no reports on previous SMF end facet devices' detection limits which have very low figures of merit.

  16. Disorder and dephasing as control knobs for light transport in optical fiber cavity networks

    PubMed Central

    Viciani, Silvia; Gherardini, Stefano; Lima, Manuela; Bellini, Marco; Caruso, Filippo

    2016-01-01

    Transport phenomena represent a very interdisciplinary topic with applications in many fields of science, such as physics, chemistry, and biology. In this context, the possibility to design a perfectly controllable experimental setup, where to tune and optimize its dynamics parameters, is a challenging but very relevant task to emulate, for instance, the transmission of energy in light harvesting processes. Here, we experimentally build a scalable and controllable transport emulator based on optical fiber cavity networks where the system noise parameters can be finely tuned while maximizing the transfer efficiency. In particular, we demonstrate that disorder and dephasing noise are two control knobs allowing one to play with constructive and destructive interference to optimize the transport paths towards an exit site. These optical setups, on one side, mimic the transport dynamics in natural photosynthetic organisms and, on the other, are very promising platforms to artificially design optimal nanoscale structures for novel, more efficient, clean energy technologies. PMID:27886246

  17. Optical clearing of melanoma in vivo: characterization by diffuse reflectance spectroscopy and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Pires, Layla; Demidov, Valentin; Vitkin, I. Alex; Bagnato, Vanderlei; Kurachi, Cristina; Wilson, Brian C.

    2016-08-01

    Melanoma is the most aggressive type of skin cancer, with significant risk of fatality. Due to its pigmentation, light-based imaging and treatment techniques are limited to near the tumor surface, which is inadequate, for example, to evaluate the microvascular density that is associated with prognosis. White-light diffuse reflectance spectroscopy (DRS) and near-infrared optical coherence tomography (OCT) were used to evaluate the effect of a topically applied optical clearing agent (OCA) in melanoma in vivo and to image the microvascular network. DRS was performed using a contact fiber optic probe in the range from 450 to 650 nm. OCT imaging was performed using a swept-source system at 1310 nm. The OCT image data were processed using speckle variance and depth-encoded algorithms. Diffuse reflectance signals decreased with clearing, dropping by ˜90% after 45 min. OCT was able to image the microvasculature in the pigmented melanoma tissue with good spatial resolution up to a depth of ˜300 μm without the use of OCA; improved contrast resolution was achieved with optical clearing to a depth of ˜750 μm in tumor. These findings are relevant to potential clinical applications in melanoma, such as assessing prognosis and treatment responses. Optical clearing may also facilitate the use of light-based treatments such as photodynamic therapy.

  18. Optical clearing of melanoma in vivo: characterization by diffuse reflectance spectroscopy and optical coherence tomography.

    PubMed

    Pires, Layla; Demidov, Valentin; Vitkin, I Alex; Bagnato, Vanderlei; Kurachi, Cristina; Wilson, Brian C

    2016-08-01

    Melanoma is the most aggressive type of skin cancer, with significant risk of fatality. Due to its pigmentation, light-based imaging and treatment techniques are limited to near the tumor surface, which is inadequate, for example, to evaluate the microvascular density that is associated with prognosis. White-light diffuse reflectance spectroscopy (DRS) and near-infrared optical coherence tomography (OCT) were used to evaluate the effect of a topically applied optical clearing agent (OCA) in melanoma in vivo and to image the microvascular network. DRS was performed using a contact fiber optic probe in the range from 450 to 650 nm. OCT imaging was performed using a swept-source system at 1310 nm. The OCT image data were processed using speckle variance and depth-encoded algorithms. Diffuse reflectance signals decreased with clearing, dropping by ∼ 90% after 45 min. OCT was able to image the microvasculature in the pigmented melanoma tissue with good spatial resolution up to a depth of ∼ 300 μm without the use of OCA; improved contrast resolution was achieved with optical clearing to a depth of ∼ 750 μm in tumor. These findings are relevant to potential clinical applications in melanoma, such as assessing prognosis and treatment responses. Optical clearing may also facilitate the use of light-based treatments such as photodynamic therapy.

  19. Numerical analysis of an optical nanoscale particles trapping device based on a slotted nanobeam cavity

    PubMed Central

    Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing

    2016-01-01

    A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future. PMID:27786248

  20. Numerical analysis of an optical nanoscale particles trapping device based on a slotted nanobeam cavity

    NASA Astrophysics Data System (ADS)

    Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing

    2016-10-01

    A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future.

  1. Coupling of erbium dopants to yttrium orthosilicate photonic crystal cavities for on-chip optical quantum memories

    SciTech Connect

    Miyazono, Evan; Zhong, Tian; Craiciu, Ioana; Kindem, Jonathan M.; Faraon, Andrei

    2016-01-04

    Erbium dopants in crystals exhibit highly coherent optical transitions well suited for solid-state optical quantum memories operating in the telecom band. Here, we demonstrate coupling of erbium dopant ions in yttrium orthosilicate to a photonic crystal cavity fabricated directly in the host crystal using focused ion beam milling. The coupling leads to reduction of the photoluminescence lifetime and enhancement of the optical depth in microns-long devices, which will enable on-chip quantum memories.

  2. X-ray free-electron laser oscillator with nuclear-resonant cavity stabilization and quantum-optical applications

    SciTech Connect

    Adams, Bernhard W.; Kim, Kwang -Je

    2016-08-09

    Here, x-ray free-electron-laser oscillators with nuclear-resonant cavity stabilization (NRS-XFELO) hold the promise for providing x-rays with unprecedented coherence properties that will enable interesting quantum-optical and metrological applications. Among these are atom optics with x-ray-based optical elements providing high momentum transfer, or a frequency standard far surpassing the best state-of the-art atomic clocks.

  3. Diffuse optical tomography in the presence of a chest wall

    NASA Astrophysics Data System (ADS)

    Ban, Han Y.; Busch, David R.; Pathak, Saurav; Moscatelli, Frank A.; Machida, Manabu; Schotland, John C.; Markel, Vadim A.; Yodh, Arjun G.

    2013-02-01

    Diffuse optical tomography (DOT) has been employed to derive spatial maps of physiologically important chromophores in the human breast, but the fidelity of these images is often compromised by boundary effects such as those due to the chest wall. We explore the image quality in fast, data-intensive analytic and algebraic linear DOT reconstructions of phantoms with subcentimeter target features and large absorptive regions mimicking the chest wall. Experiments demonstrate that the chest wall phantom can introduce severe image artifacts. We then show how these artifacts can be mitigated by exclusion of data affected by the chest wall. We also introduce and demonstrate a linear algebraic reconstruction method well suited for very large data sets in the presence of a chest wall.

  4. Variational inference with ARD prior for NIRS diffuse optical tomography.

    PubMed

    Miyamoto, Atsushi; Watanabe, Kazuho; Ikeda, Kazushi; Sato, Masa-Aki

    2015-05-01

    Diffuse optical tomography (DOT) reconstructs 3-D tomographic images of brain activities from observations by near-infrared spectroscopy (NIRS) that is formulated as an ill-posed inverse problem. This brief presents a method for NIRS DOT based on a hierarchical Bayesian approach introducing the automatic relevance determination prior and the variational Bayes technique. Although the sparseness of the estimation strongly depends on the hyperparameters, in general, our method has less dependency on the hyperparameters. We confirm through numerical experiments that a schematic phase diagram of sparseness with respect to the hyperparameters has two regions: in one region hyperparameters give sparse solutions and in the other they give dense ones. The experimental results are supported by our theoretical analyses in simple cases.

  5. Diffuse optical tomography in the presence of a chest wall

    PubMed Central

    Busch, David R.; Pathak, Saurav; Moscatelli, Frank A.; Machida, Manabu; Schotland, John C.; Markel, Vadim A.; Yodh, Arjun G.

    2013-01-01

    Abstract. Diffuse optical tomography (DOT) has been employed to derive spatial maps of physiologically important chromophores in the human breast, but the fidelity of these images is often compromised by boundary effects such as those due to the chest wall. We explore the image quality in fast, data-intensive analytic and algebraic linear DOT reconstructions of phantoms with subcentimeter target features and large absorptive regions mimicking the chest wall. Experiments demonstrate that the chest wall phantom can introduce severe image artifacts. We then show how these artifacts can be mitigated by exclusion of data affected by the chest wall. We also introduce and demonstrate a linear algebraic reconstruction method well suited for very large data sets in the presence of a chest wall. PMID:23392384

  6. Photoluminescence and optical transmission of diffusion-pump oils.

    NASA Technical Reports Server (NTRS)

    Kroes, R. L.

    1973-01-01

    The photoluminescence and optical transmission of the four widely used diffusion-pump oils, DC-705, DC-704, Convalex-10, and Convoil-20, were measured. Each of the oils was found to be transparent throughout the visible region, showed some absorption in the near-UV region, and became very opaque below approximately 300 nm. Both Convalex-10 and Convoil-20 turned yellow after exposure to UV light. No such change was noted in DC-705 or DC-704. Photoluminescence was produced in each of the four oils when irradiated with UV light. Both DC-705 and DC-704 had a nearly identical luminescence spectra that peaked at 350 nm. The spectra of Convalex-10 and Convoil-20 were fairly complex, with several peaks in the visible region.

  7. Fast Bayesian inference of optical trap stiffness and particle diffusion

    PubMed Central

    Bera, Sudipta; Paul, Shuvojit; Singh, Rajesh; Ghosh, Dipanjan; Kundu, Avijit; Banerjee, Ayan; Adhikari, R.

    2017-01-01

    Bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time. The overdamped Brownian motion of a particle confined in an optical trap is generally modelled by the Ornstein-Uhlenbeck process and can be observed directly in experiment. Here we present Bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates. This obviates the need for Monte Carlo sampling and yields methods that are both fast and accurate. We apply these to experimental data and demonstrate their advantage over commonly used non-Bayesian fitting methods. PMID:28139705

  8. Fast Bayesian inference of optical trap stiffness and particle diffusion

    NASA Astrophysics Data System (ADS)

    Bera, Sudipta; Paul, Shuvojit; Singh, Rajesh; Ghosh, Dipanjan; Kundu, Avijit; Banerjee, Ayan; Adhikari, R.

    2017-01-01

    Bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time. The overdamped Brownian motion of a particle confined in an optical trap is generally modelled by the Ornstein-Uhlenbeck process and can be observed directly in experiment. Here we present Bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates. This obviates the need for Monte Carlo sampling and yields methods that are both fast and accurate. We apply these to experimental data and demonstrate their advantage over commonly used non-Bayesian fitting methods.

  9. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

    SciTech Connect

    Svenmarker, Pontus; Xu, Can T.; Liu, Haichun; Wu, Xia; Andersson-Engels, Stefan

    2014-02-17

    We report on improved image detectability for fluorescence diffuse optical tomography using upconverting nanoparticles doped with rare-earth elements. Core-shell NaYF{sub 4}:Yb{sup 3+}/Er{sup 3+}@NaYF{sub 4} upconverting nanoparticles were synthesized through a stoichiometric method. The Yb{sup 3+}/Er{sup 3+} sensitizer-activator pair yielded two anti-Stokes shifted fluorescence emission bands at 540 nm and 660 nm, here used to a priori estimate the fluorescence source depth with sub-millimeter precision. A spatially varying regularization incorporated the a priori fluorescence source depth estimation into the tomography reconstruction scheme. Tissue phantom experiments showed both an improved resolution and contrast in the reconstructed images as compared to not using any a priori information.

  10. Diffuse optical spectroscopy of breast tissue extended to 1100 nm

    NASA Astrophysics Data System (ADS)

    Taroni, Paola; Bassi, Andrea; Comelli, Daniela; Farina, Andrea; Cubeddu, Rinaldo; Pifferi, Antonio

    2009-09-01

    The feasibility of in vivo measurements in the range of 1000 to 1100 nm and the potential benefits of operation in that wavelength range for diagnostic applications are investigated. To this purpose, an existing system for time-resolved diffuse spectroscopy is modified to enable in vivo studies to be carried out continuously from 600 to 1100 nm. The optical characterization of collagen powder is extended to 1100 nm and an accurate measurement of the absorption properties of lipid is carried out over the entire spectral range. Finally, the first in vivo absorption and scattering spectra of breast tissue are measured from 10 healthy volunteers between 600 and 1100 nm and tissue composition is evaluated in terms of blood parameters and water, lipid, and collagen content using a spectrally constrained global fitting procedure.

  11. Dynamic diffuse optical tomography imaging of peripheral arterial disease.

    PubMed

    Khalil, Michael A; Kim, Hyun K; Kim, In-Kyong; Flexman, Molly; Dayal, Rajeev; Shrikhande, Gautam; Hielscher, Andreas H

    2012-09-01

    Peripheral arterial disease (PAD) is the narrowing of arteries due to plaque accumulation in the vascular walls. This leads to insufficient blood supply to the extremities and can ultimately cause cell death. Currently available methods are ineffective in diagnosing PAD in patients with calcified arteries, such as those with diabetes. In this paper we investigate the potential of dynamic diffuse optical tomography (DDOT) as an alternative way to assess PAD in the lower extremities. DDOT is a non-invasive, non-ionizing imaging modality that uses near-infrared light to create spatio-temporal maps of oxy- and deoxy-hemoglobin in tissue. We present three case studies in which we used DDOT to visualize vascular perfusion of a healthy volunteer, a PAD patient and a diabetic PAD patient with calcified arteries. These preliminary results show significant differences in DDOT time-traces and images between all three cases, underscoring the potential of DDOT as a new diagnostic tool.

  12. Multibeam fluorescence diffuse optical tomography using upconverting nanoparticles.

    PubMed

    Liu, Haichun; Xu, Can T; Andersson-Engels, Stefan

    2010-03-01

    Fluorescence diffuse optical tomography (FDOT) is a biomedical imaging modality that can be used for localization and quantification of fluorescent molecules inside turbid media. In this ill-posed problem, the reconstruction quality is directly determined by the amount and quality of the information obtained from the boundary measurements. Regularly, more information can be obtained by increasing the number of excitation positions in an FDOT system. However, the maximum number of excitation positions is limited by the finite size of the excitation beam. In the present work, we demonstrate a method in FDOT to exploit the unique nonlinear power dependence of upconverting nanoparticles to further increase the amount of information in a raster-scanning setup by including excitation with two beams simultaneously. We show that the additional information can be used to obtain more accurate reconstructions.

  13. Optical control of NMDA receptors with a diffusible photoswitch

    PubMed Central

    Laprell, Laura; Repak, Emilienne; Franckevicius, Vilius; Hartrampf, Felix; Terhag, Jan; Hollmann, Michael; Sumser, Martin; Rebola, Nelson; DiGregorio, David A.; Trauner, Dirk

    2015-01-01

    N-methyl-D-aspartate receptors (NMDARs) play a central role in synaptic plasticity, learning and memory, and are implicated in various neuronal disorders. We synthesized a diffusible photochromic glutamate analogue, azobenzene-triazole-glutamate (ATG), which is specific for NMDARs and functions as a photoswitchable agonist. ATG is inactive in its dark-adapted trans-isoform, but can be converted into its active cis-isoform using one-photon (near UV) or two-photon (740 nm) excitation. Irradiation with violet light photo-inactivates ATG within milliseconds, allowing agonist removal on the timescale of NMDAR deactivation. ATG is compatible with Ca2+ imaging and can be used to optically mimic synaptic coincidence detection protocols. Thus, ATG can be used like traditional caged glutamate compounds, but with the added advantages of NMDAR specificity, low antagonism of GABAR-mediated currents, and precise temporal control of agonist delivery. PMID:26311290

  14. Low-cost diffuse optical tomography for the classroom

    NASA Astrophysics Data System (ADS)

    Minagawa, Taisuke; Zirak, Peyman; Weigel, Udo M.; Kristoffersen, Anna K.; Mateos, Nicolas; Valencia, Alejandra; Durduran, Turgut

    2012-10-01

    Diffuse optical tomography (DOT) is an emerging imaging modality with potential applications in oncology, neurology, and other clinical areas. It allows the non-invasive probing of the tissue function using relatively inexpensive and safe instrumentation. An educational laboratory setup of a DOT system could be used to demonstrate how photons propagate through tissues, basics of medical tomography, and the concepts of multiple scattering and absorption. Here, we report a DOT setup that could be introduced to the advanced undergraduate or early graduate curriculum using inexpensive and readily available tools. The basis of the system is the LEGO Mindstorms NXT platform which controls the light sources, the detectors (photo-diodes), a mechanical 2D scanning platform, and the data acquisition. A basic tomographic reconstruction is implemented in standard numerical software, and 3D images are reconstructed. The concept was tested and developed in an educational environment that involved a high-school student and a group of post-doctoral fellows.

  15. Diffuse optical methods for assessing breast cancer chemotherapy

    NASA Astrophysics Data System (ADS)

    Tromberg, Bruce J.

    2014-03-01

    In his talk, "Diffuse Optical Methods for Assessing Breast Cancer Chemotherapy," SPIE Fellow Bruce Tromberg (Beckman Laser Institute and Medical Clinic) describes a method combining frequency domain photon migration, essentially a method of tracking photon motion in tissue, with a NIR spectroscopy technique using 850nm LEDs. The result is a scatter corrected absorption spectra. The technique takes advantage of elevated blood and water levels and decreased lipid levels in the presence of tumors to provide a more accurate mapping of the breast, allowing more effective treatment. Tromberg's team recently completed their first full mapping of the breast and have taken the instrument from a standalone unit to a portable one suitable for travel. In addition to providing feedback to enhance breast cancer treatment, Tromberg expects that this technique will be applicable in treating other forms of cancer as well.

  16. Diffuse optical tomography using multi-directional sources and detectors

    PubMed Central

    Shimokawa, Takeaki; Ishii, Toshihiro; Takahashi, Yoichiro; Sugawara, Satoru; Sato, Masa-aki; Yamashita, Okito

    2016-01-01

    Diffuse optical tomography (DOT) is an advanced imaging method used to visualize the internal state of biological tissues as 3D images. However, current continuous-wave DOT requires high-density probe arrays for measurement (less than 15-mm interval) to gather enough information for 3D image reconstruction, which makes the experiment time-consuming. In this paper, we propose a novel DOT measurement system using multi-directional light sources and multi-directional photodetectors instead of high-density probe arrays. We evaluated this system’s multi-directional DOT through computer simulation and a phantom experiment. From the results, we achieved DOT with less than 5-mm localization error up to a 15-mm depth with low-density probe arrays (30-mm interval), indicating that the multi-directional measurement approach allows DOT without requiring high-density measurement. PMID:27446694

  17. CLASSICAL AREAS OF PHENOMENOLOGY: Design of novel three port optical gates scheme for the integration of large optical cavity electroabsorption modulators and evanescently-coupled photodiodes

    NASA Astrophysics Data System (ADS)

    Liao, Zai-Yi; Yang, Hua; Wang, Wei

    2008-07-01

    This paper presents a novel scheme to monolithically integrate an evanescently-coupled uni-travelling carrier photodiode with a planar short multimode waveguide structure and a large optical cavity electroabsorption modulator based on a multimode waveguide structure. By simulation, both electroabsorption modulator and photodiode show excellent optical performances. The device can be fabricated with conventional photolithography, reactive ion etching, and chemical wet etching.

  18. Diffuse reflectance spectroscopy of epithelial tissue with a smart fiber-optic probe.

    PubMed

    Yu, Bing; Shah, Amy; Nagarajan, Vivek K; Ferris, Daron G

    2014-03-01

    Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, fast and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current DRS systems are susceptible to several sources of systematic and random errors, such as uncontrolled probe-to-tissue pressure and lack of a real-time calibration that can significantly impair the measurement accuracy, reliability and validity of this technology as well as its clinical utility. In addition, such systems use bulky, high power and expensive optical components which impede their widespread use in low- and middle-income countries (LMICs) where epithelial cancer related death is disproportionately high. In this paper we report a portable, easy-to-use and low cost, yet accurate and reliable DRS device that can aid in the screening and diagnosis of oral and cervical cancer. The device uses an innovative smart fiber-optic probe to eliminate operator bias, state-of-the-art photonics components to reduce size and power consumption, and automated software to reduce the need of operator training. The device showed a mean error of 1.4 ± 0.5% and 6.8 ± 1.7% for extraction of phantom absorption and reduced scattering coefficients, respectively. A clinical study on healthy volunteers indicated that a pressure below 1.0 psi is desired for oral mucosal tissues to minimize the probe effects on tissue physiology and morphology.

  19. Diffuse reflectance spectroscopy of epithelial tissue with a smart fiber-optic probe

    PubMed Central

    Yu, Bing; Shah, Amy; Nagarajan, Vivek K.; Ferris, Daron G.

    2014-01-01

    Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, fast and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current DRS systems are susceptible to several sources of systematic and random errors, such as uncontrolled probe-to-tissue pressure and lack of a real-time calibration that can significantly impair the measurement accuracy, reliability and validity of this technology as well as its clinical utility. In addition, such systems use bulky, high power and expensive optical components which impede their widespread use in low- and middle-income countries (LMICs) where epithelial cancer related death is disproportionately high. In this paper we report a portable, easy-to-use and low cost, yet accurate and reliable DRS device that can aid in the screening and diagnosis of oral and cervical cancer. The device uses an innovative smart fiber-optic probe to eliminate operator bias, state-of-the-art photonics components to reduce size and power consumption, and automated software to reduce the need of operator training. The device showed a mean error of 1.4 ± 0.5% and 6.8 ± 1.7% for extraction of phantom absorption and reduced scattering coefficients, respectively. A clinical study on healthy volunteers indicated that a pressure below 1.0 psi is desired for oral mucosal tissues to minimize the probe effects on tissue physiology and morphology. PMID:24688805

  20. Optic nerve diffusion tensor imaging after acute optic neuritis predicts axonal and visual outcomes.

    PubMed

    van der Walt, Anneke; Kolbe, Scott C; Wang, Yejun E; Klistorner, Alexander; Shuey, Neil; Ahmadi, Gelareh; Paine, Mark; Marriott, Mark; Mitchell, Peter; Egan, Gary F; Butzkueven, Helmut; Kilpatrick, Trevor J

    2013-01-01

    Early markers of axonal and clinical outcomes are required for early phase testing of putative neuroprotective therapies for multiple sclerosis (MS). To assess whether early measurement of diffusion tensor imaging (DTI) parameters (axial and radial diffusivity) within the optic nerve during and after acute demyelinating optic neuritis (ON) could predict axonal (retinal nerve fibre layer thinning and multi-focal visual evoked potential amplitude reduction) or clinical (visual acuity and visual field loss) outcomes at 6 or 12 months. Thirty-seven patients presenting with acute, unilateral ON were studied at baseline, one, three, six and 12 months using optic nerve DTI, clinical and paraclinical markers of axonal injury and clinical visual dysfunction. Affected nerve axial diffusivity (AD) was reduced at baseline, 1 and 3 months. Reduced 1-month AD correlated with retinal nerve fibre layer (RNFL) thinning at 6 (R=0.38, p=0.04) and 12 months (R=0.437, p=0.008) and VEP amplitude loss at 6 (R=0.414, p=0.019) and 12 months (R=0.484, p=0.003). AD reduction at three months correlated with high contrast visual acuity at 6 (ρ = -0.519, p = 0.001) and 12 months (ρ = -0.414, p=0.011). The time-course for AD reduction for each patient was modelled using a quadratic regression. AD normalised after a median of 18 weeks and longer normalisation times were associated with more pronounced RNFL thinning and mfVEP amplitude loss at 12 months. Affected nerve radial diffusivity (RD) was unchanged until three months, after which time it remained elevated. These results demonstrate that AD reduces during acute ON. One month AD reduction correlates with the extent of axonal loss and persistent AD reduction at 3 months predicts poorer visual outcomes. This suggests that acute ON therapies that normalise optic nerve AD by 3 months could also promote axon survival and improve visual outcomes.