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Sample records for all-solid photonic bandgap

  1. Refractive index sensing in an all-solid twin-core photonic bandgap fiber

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Town, Graham E.; Bang, Ole

    2010-01-01

    We describe a highly sensitive refractive index sensor based on a twin-core coupler in an all-solid photonic bandgap guiding optical fiber. A single hole acts as a microfluidic channel for the analyte, which modifies the coupling between the cores, and avoids the need for selective filling....... By operating in the bandgap guiding regime the proposed sensor is capable of measuring refractive indices around that of water, and because the analyte varies the coupling coefficient (i.e., instead of phase matching condition) the device is capable of both high sensitivity and a relatively large dynamic range....

  2. Photonic Bandgap Propagation in All-Solid Chalcogenide Microstructured Optical Fibers

    Directory of Open Access Journals (Sweden)

    Celine Caillaud

    2014-08-01

    Full Text Available An original way to obtain fibers with special chromatic dispersion and single-mode behavior is to consider microstructured optical fibers (MOFs. These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. In this study, the first all-solid all-chalcogenide MOFs exhibiting photonic bandgap transmission have been achieved and optically characterized. The fibers are made of an As38Se62 matrix, with inclusions of Te20As30Se50 glass that shows a higher refractive index (n = 2.9. In those fibers, several transmission bands have been observed in mid infrared depending on the geometry. In addition, for the first time, propagation by photonic bandgap effect in an all-chalcogenide MOF has been observed at 3.39 µm, 9.3 µm, and 10.6 µm. The numerical simulations based on the optogeometric properties of the fibers agree well with the experimental characterizations.

  3. Characteristics of Bragg Gratings in All-Solid Photonic Bandgap Fiber

    Institute of Scientific and Technical Information of China (English)

    Bai-Ou Guan; Zhi Wang; Yang Zhang; Da Chen

    2008-01-01

    We report on fiber Bragg gratings in all-solid photonie bandgap fiber that was composed of a triangular array of high-index Ge-doped rods in pure silica background with fluorine-doped index-depressed layer surrounding the Ge-doped rod. Fiber Bragg gratings were photowritten with 193 nm ArF excimer laser and characterized for their response to strain, temperature, bending, and torsion. These gratings couple light from the forward core mode to not only backward core mode but also backward rod modes. This results in multiple resonance peaks in the reflection spectrum. All resonance wavelengths exhibited the same temperature and strain response with coefficient similar to that of Bragg gratings in standard single-mode fiber. The strength of the resonance peaks corresponding to the backward rod modes showed high sensitivity to bending and torsion.

  4. A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings

    Institute of Scientific and Technical Information of China (English)

    Fang Hong; Lou Shu-Qin; Guo Tie-Ying; Yao Lei; Li nong-Lei; Jian ShuiSheng

    2008-01-01

    A simple model for approximate bandgap structure caculation of all-solid photonic bandgap fibre based on an array of rings is proposed.In this model calculated are only the potential modes of a unit cell,which is a high-index ring in the low-index background for this fibre,rather than the whole cladding periodic structure based on Bloch's theorem to find the bandgap.Its accuracy is proved by comparing its results with the results obtained by using the accurate full-vector plane-wave method.High speed in computation is its great advantage over the other exact methods,because it only needs to find the roots of one-dimensional analytical expressions.And the results of this model,mode plots,offer an ideal environment to explore the basic properties of photonic bandgap clearly.

  5. Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Barkou, Stig Eigil; Broeng, Jes; Bjarklev, Anders Overgaard

    1999-01-01

    Photonic bandgap fibers are describes using a new Kagomé cladding structure. These fibers may potentially guide light in low-index regions. Such fibers offer new dispersion properties, and large design flexibility.......Photonic bandgap fibers are describes using a new Kagomé cladding structure. These fibers may potentially guide light in low-index regions. Such fibers offer new dispersion properties, and large design flexibility....

  6. Photonic Bandgap (PBG) Shielding Technology

    Science.gov (United States)

    Bastin, Gary L.

    2007-01-01

    Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects

  7. Polarization properties of photonic bandgap fibers

    DEFF Research Database (Denmark)

    Broeng, Jes; Libori, Stig E. Barkou; Bjarklev, Anders Overgaard

    2000-01-01

    We present the first analysis of polarization properties of photonic bandgap fibers. Strong birefringence may be obtained for modest non-uniformities in and around the core region, suggesting the use of photonic bandgap fibers as polarization maintaining components.......We present the first analysis of polarization properties of photonic bandgap fibers. Strong birefringence may be obtained for modest non-uniformities in and around the core region, suggesting the use of photonic bandgap fibers as polarization maintaining components....

  8. Photonic bandgap structures

    CERN Document Server

    Marco, Pisco; Antonello, Cutolo

    2012-01-01

    This E-Book covers the research and the development of a novel generation of photonic devices for sensing applications. Key features of this book include a brief review of basic PhCs related design and fabrication concepts, a selection of crossover topics for the development of novel technological platforms for physical, chemical and biological sensing and a description of the main PhCs sensors to date by representing many of the exciting sensing applications that utilize photonic crystal structures.

  9. Surface state photonic bandgap cavities

    OpenAIRE

    Rahachou, A. I.; Zozoulenko, I. V.

    2005-01-01

    We propose and analyze a new type of a resonant high-Q cavity for lasing, sensing or filtering applications, which is based on a surface states of a finite photonic crystal. We demonstrate that such the cavity can have a Q factor comparable with that one of conventional photonic band-gap defect mode cavities. At the same time, the distinguished feature of the surface mode cavity is that it is situated directly at the surface of the photonic crystal. This might open up new possibilities for de...

  10. Photonic bandgap fiber bundle spectrometer

    CERN Document Server

    Hang, Qu; Syed, Imran; Guo, Ning; Skorobogatiy, Maksim

    2010-01-01

    We experimentally demonstrate an all-fiber spectrometer consisting of a photonic bandgap fiber bundle and a black and white CCD camera. Photonic crystal fibers used in this work are the large solid core all-plastic Bragg fibers designed for operation in the visible spectral range and featuring bandgaps of 60nm - 180nm-wide. 100 Bragg fibers were chosen to have complimentary and partially overlapping bandgaps covering a 400nm-840nm spectral range. The fiber bundle used in our work is equivalent in its function to a set of 100 optical filters densely packed in the area of ~1cm2. Black and white CCD camera is then used to capture spectrally "binned" image of the incoming light at the output facet of a fiber bundle. To reconstruct the test spectrum from a single CCD image we developed an algorithm based on pseudo-inversion of the spectrometer transmission matrix. We then study resolution limit of this spectroscopic system by testing its performance using spectrally narrow test peaks (FWHM 5nm-25nm) centered at va...

  11. High sensitivity high temperature sensor based on SMS structure with large-core all-solid bandgap fiber as the multimode section

    Science.gov (United States)

    Franco, Marcos A. R.; Cruz, Alice L. S.; Serrão, Valdir A.; Barbosa, Carmem L.

    2014-05-01

    A fiber optic interferometric device based on a singlemode-multimode-singlemode (SMS) structure is proposed as a high sensitive high temperature sensor. The multimode section (MMF) consists of a large-core all-solid photonic bandgap fiber (AS-PBF) with silica as the background material and germanium-doped silica at the high index regions. The numerical analyses were carried out by beam propagation method. The numerical results indicate a constant high temperature sensitivity of ~-35 pm/°C over a large temperature range from 20oC to 930°C.

  12. Actively doped solid core Photonic Bandgap Fiber

    DEFF Research Database (Denmark)

    Broeng, Jes; Olausson, Christina Bjarnal Thulin; Lyngsøe, Jens Kristian;

    2010-01-01

    Solid photonic bandgap fibers offer distributed spectral filtering with extraordinary high suppression. This opens new possibilities of artificially tailoring the gain spectrum of fibers. We present record-performance of such fibers and outline their future applications....

  13. Advances in photonic bandgap fiber functionality

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian

    In order to take advantage of the many intriguing optical properties of photonic bandgap fibers, there are some technological challenges that have to be addressed. Among other things this includes transmission loss and the fibers ability to maintain field polarization. The work presented in this ......In order to take advantage of the many intriguing optical properties of photonic bandgap fibers, there are some technological challenges that have to be addressed. Among other things this includes transmission loss and the fibers ability to maintain field polarization. The work presented...

  14. Gaussian Filtering with Tapered Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2006-01-01

    We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm......We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm...

  15. Air-guiding Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Hansen, Theis Peter

    2005-01-01

    Photonic bandgap fibers that guide light in an air core have attracted much interest since their first demonstration in 1999. The prospect of low-loss guiding of light in air has importance for a multitude of applications, such as data transmission, gas sensors, dispersion compensation and guiding...

  16. Ultrasensitive refractive index sensor based on twin-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Town, Graham E.; Bang, Ole

    We have theoretically investigated twin-core all-solid photonic bandgap fibers (PBGFs) for evanescent wave sensing of refractive index within one single microfluidic analyte channel centered between the two cores. The sensor can achieve ultrahigh sensitivity by detecting the change in transmission...

  17. Two-dimensional Kagome photonic bandgap waveguide

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou;

    2000-01-01

    The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

  18. Advances in Solid Core Photonic Bandgap Fiber Amplifiers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Petersen, Sidsel Rübner;

    2012-01-01

    We present recent development of photonic crystal fiber amplifiers containing photonic bandgap structures for enhanced spectral and modal filtering functionality.......We present recent development of photonic crystal fiber amplifiers containing photonic bandgap structures for enhanced spectral and modal filtering functionality....

  19. A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate

    Institute of Scientific and Technical Information of China (English)

    林青春; 朱方明; 何赛灵

    2004-01-01

    A new photonic bandgap (PBG) cover for a patch antenna with a photonic bandgap substrate is introduced. The plane wave expansion method and the FDTD method were used to calculate such an antenna system. Numerical results for the input return loss, radiation pattern, surface wave, and the directivity of the antennas are presented. A comparison between the conventional patch antenna and the new PBG antenna is given. It is shown that the new PBG cover is very efficient for improving the radiation directivity. The physical reasons for the improvement are also given.

  20. Hybrid photonic-bandgap accelerating cavities

    CERN Document Server

    Di Gennaro, E; Savo, S; Andreone, A; Masullo, M R; Castaldi, G; Gallina, I; Galdi, V

    2009-01-01

    In a recent investigation, we studied two-dimensional point-defected photonic bandgap cavities composed of dielectric rods arranged according to various representative periodic and aperiodic lattices, with special emphasis on possible applications to particle acceleration (along the longitudinal axis). In this paper, we present a new study aimed at highlighting the possible advantages of using hybrid structures based on the above dielectric configurations, but featuring metallic rods in the outermost regions, for the design of extremely-high quality factor, bandgap-based, accelerating resonators. In this framework, we consider diverse configurations, with different (periodic and aperiodic) lattice geometries, sizes, and dielectric/metal fractions. Moreover, we also explore possible improvements attainable via the use of superconducting plates to confine the electromagnetic field in the longitudinal direction. Results from our comparative studies, based on numerical full-wave simulations backed by experimental...

  1. Single-photon propagation through dielectric bandgaps.

    Science.gov (United States)

    Borjemscaia, Natalia; Polyakov, Sergey V; Lett, Paul D; Migdall, Alan

    2010-02-01

    Theoretical models of photon traversal through quarter-wave dielectric stack barriers that arise due to Bragg reflection predict the saturation of the propagation time with the barrier length, known as the Hartman effect. This saturation is sensitive to the addition of single dielectric layers, varying significantly from sub-luminal to apparently super-luminal and vice versa. Our research tests the suitability of photonic bandgaps as an optical model for the tunneling process. Of particular importance is our observation of subtle structural changes in dielectric stacks drastically affecting photon traversal times, allowing for apparent sub- and super-luminal effects. We also introduce a simple model to link HOM visibility to wavepacket distortion that allows us to exclude this as a possible cause of the loss of contrast in the barrier penetration process. PMID:20174056

  2. Modeling of realistic cladding structures for photonic bandgap fibers

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Nielsen, Martin Dybendal

    2004-01-01

    Cladding structures of photonic bandgap fibers often have airholes of noncircular shape, and, typically, close-to-hexagonal airholes with curved corners are observed. We study photonic bandgaps in such structures by aid of a two-parameter representation of the size and curvature. For the fundamen......Cladding structures of photonic bandgap fibers often have airholes of noncircular shape, and, typically, close-to-hexagonal airholes with curved corners are observed. We study photonic bandgaps in such structures by aid of a two-parameter representation of the size and curvature. For the...... fundamental bandgap we find that the bandgap edges (the intersections with the air line) shift toward shorter wavelengths when the air-filling fraction f is increased. The bandgap also broadens, and the relative bandwidth increases exponentially with f2. Compared with recent experiments [Nature 424, 657 (2003...

  3. Highly dispersive photonic band-gap prism

    International Nuclear Information System (INIS)

    We propose the concept of a photonic band-gap (PBG) prism based on two-dimensional PBG structures and realize it in the millimeter-wave spectral regime. We recognize the highly nonlinear dispersion of PBG materials near Brillouin zone edges and utilize the dispersion to achieve strong prism action. Such a PBG prism is very compact if operated in the optical regime, ∼20μm in size for λ∼700nm, and can serve as a dispersive element for building ultracompact miniature spectrometers. copyright 1996 Optical Society of America

  4. Highly dispersive photonic band-gap prism.

    Science.gov (United States)

    Lin, S Y; Hietala, V M; Wang, L; Jones, E D

    1996-11-01

    We propose the concept of a photonic band-gap (PBG) prism based on two-dimensional PBG structures and realize it in the millimeter-wave spectral regime. We recognize the highly nonlinear dispersion of PBG materials near Brillouin zone edges and utilize the dispersion to achieve strong prism action. Such a PBG prism is very compact if operated in the optical regime, ~20 mm in size for lambda ~ 700 nm, and can serve as a dispersive element for building ultracompact miniature spectrometers. PMID:19881796

  5. Extending of flat normal dispersion profile in all-solid soft glass nonlinear photonic crystal fibres

    Science.gov (United States)

    Siwicki, Bartłomiej; Kasztelanic, Rafał; Klimczak, Mariusz; Cimek, Jarosław; Pysz, Dariusz; Stępień, Ryszard; Buczyński, Ryszard

    2016-06-01

    The bandwidth of coherent supercontinuum generated in optical fibres is strongly determined by the all-normal dispersion characteristic of the fibre. We investigate all-normal dispersion limitations in all-solid oxide-based soft glass photonic crystal fibres with various relative inclusion sizes and lattice constants. The influence of material dispersion on fibre dispersion characteristics for a selected pair of glasses is also examined. A relation between the material dispersion of the glasses and the fibre dispersion has been described. We determined the parameters which limit the maximum range of flattened all-normal dispersion profile achievable for the considered pair of heavy-metal-oxide soft glasses.

  6. Electrically tunable liquid crystal photonic bandgap fiber laser

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei;

    2010-01-01

    We demonstrate electrical tunability of a fiber laser by using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all......-spliced laser cavity based on a liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065nm by applying...

  7. Hybrid photonic-bandgap accelerating cavities

    Science.gov (United States)

    Di Gennaro, E.; Zannini, C.; Savo, S.; Andreone, A.; Masullo, M. R.; Castaldi, G.; Gallina, I.; Galdi, V.

    2009-11-01

    In a recent investigation, we studied two-dimensional (2D) point-defected photonic bandgap cavities composed of dielectric rods arranged according to various representative periodic and aperiodic lattices, with special emphasis on possible applications to particle acceleration (along the longitudinal axis). In this paper, we present a new study aimed at highlighting the possible advantages of using hybrid structures based on the above dielectric configurations, but featuring metallic rods in the outermost regions, for the design of extremely high quality factor, bandgap-based, accelerating resonators. In this framework, we consider diverse configurations, with different (periodic and aperiodic) lattice geometries, sizes and dielectric/metal fractions. Moreover, we also explore possible improvements attainable via the use of superconducting plates to confine the electromagnetic field in the longitudinal direction. Results from our comparative studies, based on numerical full-wave simulations backed by experimental validations (at room and cryogenic temperatures) in the microwave region, identify the candidate parametric configurations capable of yielding the highest quality factor.

  8. Hybrid photonic-bandgap accelerating cavities

    Energy Technology Data Exchange (ETDEWEB)

    Di Gennaro, E [CNISM and Department of Physics, University of Naples ' Federico II' , Naples (Italy); Zannini, C; Savo, S; Andreone, A [CNR-INFM ' Coherentia' and Department of Physics, University of Naples ' Federico II' , Naples (Italy); Masullo, M R [INFN-Naples Unit, Naples (Italy); Castaldi, G; Gallina, I; Galdi, V [Waves Group, Department of Engineering, University of Sannio, Benevento (Italy)], E-mail: masullo@na.infn.it

    2009-11-15

    In a recent investigation, we studied two-dimensional (2D) point-defected photonic bandgap cavities composed of dielectric rods arranged according to various representative periodic and aperiodic lattices, with special emphasis on possible applications to particle acceleration (along the longitudinal axis). In this paper, we present a new study aimed at highlighting the possible advantages of using hybrid structures based on the above dielectric configurations, but featuring metallic rods in the outermost regions, for the design of extremely high quality factor, bandgap-based, accelerating resonators. In this framework, we consider diverse configurations, with different (periodic and aperiodic) lattice geometries, sizes and dielectric/metal fractions. Moreover, we also explore possible improvements attainable via the use of superconducting plates to confine the electromagnetic field in the longitudinal direction. Results from our comparative studies, based on numerical full-wave simulations backed by experimental validations (at room and cryogenic temperatures) in the microwave region, identify the candidate parametric configurations capable of yielding the highest quality factor.

  9. Novel 1-D Sandwich Photonic Bandgap Structure

    Institute of Scientific and Technical Information of China (English)

    庞云波; 高葆新

    2004-01-01

    A sandwich photonic bandgap (PBG) structure is a novel PBG structure whose periodic lattice is buried in the middle of a substrate. Neither drilling nor suspending the substrate is required, and the integrity of the ground plane is maintained. This paper presents several modification techniques for sandwich PBG structure fabrication. The forbidden gap can be improved by adopting the chirping technique, applying the tapering technique, enlarging the periodic elements, adjusting the location of the periodic lattice in the substrate, and using different dielectric media H-shape elements. A finite difference time domain method is applied to analyze the structures. Deep and wide stopbands can be obtained using the modified sandwich structures. Experimental measurement results agree well with the theoretical analysis.

  10. Main Factors for Affecting Photonic Bandgap of Photonic Crystals

    Institute of Scientific and Technical Information of China (English)

    LI Xia; XUE Wei; JIANG Yu-rong; YU Zhi-nong; WANG Hua-qing

    2007-01-01

    The factors affecting one dimensional (1D) and two dimensional (2D) photonic crystals (PhCs) are systemically analyzed in this paper by numerical simulation.Transfer matrix method (TMM) is employed for 1D PCs, both finite difference time domain method (FDTD) and plane wave expansion method (PWE) are employed for 2D PCs.The result shows that the photonic bandgaps (PBG) are directly affected by crystal type, crystal lattice constant, modulation of refractive index and periodicity, and it is should be useful for design of different type photonic crystals with the required PBG and functional devices.Finally, as an example, a near-IR 1D PCs narrow filter was designed.

  11. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.;

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  12. Large-area single-mode photonic bandgap vcsels

    DEFF Research Database (Denmark)

    Birkedal, Dan; Gregersen, N.; Bischoff, S.;

    2003-01-01

    We demonstrate that the photonic bandgap effect can be used to control the modes of large area vertical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a 10-micron area device.......We demonstrate that the photonic bandgap effect can be used to control the modes of large area vertical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a 10-micron area device....

  13. All-solid birefringent hybrid photonic crystal fiber based interferometric sensor for measurement of strain and temperature

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Scott Wu; Zhang, A. Ping;

    2011-01-01

    A highly sensitive fiber-optic interferometric sensor based on an all-solid birefringent hybrid photonic crystal fiber (PCF) is demonstrated for measuring strain and temperature. A strain sensitivity of similar to 23.8 pm/mu epsilon and a thermal sensitivity of similar to-1.12 nm/degrees C...

  14. Thermal tunability of photonic bandgaps in liquid crystal filled polymer photonic crystal fiber

    Science.gov (United States)

    Wang, Doudou; Chen, Guoxiang; Wang, Lili

    2016-05-01

    A highly tunable bandgap-guiding polymer photonic crystal fiber is designed by infiltrating the cladding air holes with liquid crystal 5CB. Structural parameter dependence and thermal tunability of the photonic bandgaps, mode properties and confinement losses of the designed fiber are investigated. Bandgaps red shift as the temperature goes up. Average thermal tuning sensitivity of 30.9 nm/°C and 20.6 nm/°C is achieved around room temperature for the first and second photonic bandgap, respectively. Our results provide theoretical references for applications of polymer photonic crystal fiber in sensing and tunable fiber-optic devices.

  15. Properties of photonic bandgap in one-dimensional multicomponent photonic crystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi; WANG Qi

    2006-01-01

    Properties of photonic band gap and light propagation in one-dimensional multicomponent photonic crystal have been studied with the optical transfer matrix method.We mainly analyze the relation of photonic band-gap property with the arrangement of components,the refractive index and the geometrical thickness.In this study,the methods to change the width and the location of the existing photonic band-gaps in multicomponent photonic crystal are proposed.

  16. Effect of Dielectric Constant Contrast and Filling Factor to Photonic Bandgap

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The effect of dielectric constant contrast and the filling factor to the photonic bandgap in a 2-D square lattice photonic crystal is discussed. The location, width and number of photonic bandgap can be modulated.

  17. Gas sensing using air-guiding photonic bandgap fibers

    DEFF Research Database (Denmark)

    Ritar, Tuomo; Tuominen, J.; Ludvigsen, Hanne;

    2004-01-01

    We demonstrate the high sensitivity of gas sensing using a novel air-guiding photonic bandgap fiber. The bandgap fiber is spliced to a standard single-mode fiber at the input end for easy coupling and filled with gas through the other end placed in a vacuum chamber. The technique is applied to ch...... to characterize absorption lines of acetylene and hydrogen cyanide employing a tunable laser as light source. Measurements with a LED are also performed for comparison. Detection of weakly absorbing gases such as methane and ammonia is explored.......We demonstrate the high sensitivity of gas sensing using a novel air-guiding photonic bandgap fiber. The bandgap fiber is spliced to a standard single-mode fiber at the input end for easy coupling and filled with gas through the other end placed in a vacuum chamber. The technique is applied...

  18. High-Efficiency Solar Cells Using Photonic-Bandgap Materials

    Science.gov (United States)

    Dowling, Jonathan; Lee, Hwang

    2005-01-01

    Solar photovoltaic cells would be designed to exploit photonic-bandgap (PBG) materials to enhance their energy-conversion efficiencies, according to a proposal. Whereas the energy-conversion efficiencies of currently available solar cells are typically less than 30 percent, it has been estimated that the energy-conversion efficiencies of the proposed cells could be about 50 percent or possibly even greater. The primary source of inefficiency of a currently available solar cell is the mismatch between the narrow wavelength band associated with the semiconductor energy gap (the bandgap) and the broad wavelength band of solar radiation. This mismatch results in loss of power from both (1) long-wavelength photons, defined here as photons that do not have enough energy to excite electron-hole pairs across the bandgap, and (2) short-wavelength photons, defined here as photons that excite electron- hole pairs with energies much above the bandgap. It follows that a large increase in efficiency could be obtained if a large portion of the incident solar energy could be funneled into a narrow wavelength band corresponding to the bandgap. In the proposed approach, such funneling would be effected by use of PBG materials as intermediaries between the Sun and photovoltaic cells.

  19. Ultrasensitive twin-core photonic bandgap fiber refractive index sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Town, Graham; Bang, Ole

    2009-01-01

    We propose a microfluidic refractive index sensor based on new polymer twin-core photonic bandgap fiber (PBGF). The sensor can achieve ultrahigh detection limit, i.e. >1.4times10-7RIU refractive index unit (RIU), by measuring the coupling wavelength shift.......We propose a microfluidic refractive index sensor based on new polymer twin-core photonic bandgap fiber (PBGF). The sensor can achieve ultrahigh detection limit, i.e. >1.4times10-7RIU refractive index unit (RIU), by measuring the coupling wavelength shift....

  20. Design of photonic bandgap fibers by topology optimization

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Sigmund, Ole; Feurer, Thomas

    2010-01-01

    A method based on topology optimization is presented to design the cross section of hollow-core photonic bandgap fibers for minimizing energy loss by material absorption. The optical problem is modeled by the timeharmonic wave equation and solved with the finite element program Comsol Multiphysics...

  1. Mode Division Multiplexing Exploring Hollow-Core Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Xu, Jing; Lyngso, Jens Kristian; Leick, Lasse;

    2013-01-01

    We review our recent exploratory investigations on mode division multiplexing using hollow-core photonic bandgap fibers (HC-PBGFs). Compared with traditional multimode fibers, HC-PBGFs have several attractive features such as ultra-low nonlinearities, low-loss transmission window around 2 µm etc...

  2. Optically controlled photonic bandgap structures for microstrip circuits

    CERN Document Server

    Cadman, D A

    2003-01-01

    This thesis is concerned with the optical control of microwave photonic bandgap circuits using high resistivity silicon. Photoconducting processes that occur within silicon are investigated. The influence of excess carrier density on carrier mobility and lifetime is examined. In addition, electron-hole pair recombination mechanisms (Shockley-Read-Hall, Auger, radiative and surface) are investigated. The microwave properties of silicon are examined, in particular the variation of silicon reflectivity with excess carrier density. Filtering properties of microstrip photonic bandgap structures and how they may be controlled optically are studied. A proof-of-concept microstrip photonic bandgap structure with optical control is designed, simulated and measured. With no optical illumination incident upon the silicon, the microstrip photonic bandgap structure's filtering properties are well-defined; a 3dB stopband width of 2.6GHz, a 6dB bandwidth of 2GHz and stopband depth of -11.6dB at the centre frequency of 9.9GHz...

  3. Bandgap properties of low index contrast aperiodically ordered photonic quasicrystals

    CERN Document Server

    Zito, Gianluigi; Di Gennaro, Emiliano; Andreone, Antonello; Santamato, Enrico; Abbate, Giancarlo

    2009-01-01

    We numerically analyze, using Finite Difference Time Domain simulations, the bandgap properties of photonic quasicrystals with a low index contrast. We compared 8-, 10- and 12-fold symmetry aperiodically ordered lattices with different spatial tiling. Our results show that tiling design, more than symmetry, determines the transmission properties of these structures.

  4. All-solid-state cavity QED using Anderson-localized modes in disordered photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lodahl, Peter; Sapienza, Luca; Nielsen, Henri Thyrrestrup;

    2010-01-01

    We employ Anderson-localized modes in deliberately disordered photonic crystal waveguides to confine light and enhance the interaction with matter. A 15-fold enhancement of the decay rate of a single quantum dot is observed meaning that 94% of the emitted single photons are coupled to an Anderson...

  5. Biased liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard;

    2008-01-01

    We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure.......We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure....

  6. Temperature Compensated Strain Sensor Based on Cascaded Sagnac Interferometers and All-Solid Birefringent Hybrid Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Wu; He, Sailing;

    2012-01-01

    We demonstrate a temperature compensated strain sensor with two cascaded Sagnac interferometers, that provide strain sensing and temperature compensation, respectively. The Sagnac interferometers use an all-solid hybrid photonic crystal fiber with stress-induced birefringence. The stress......-induced birefringent fiber is known to offer the maximum strain sensitivity, but also to suffer from temperature crosstalk. Our experimental results show that the cascaded Sagnac sensor can suppress the crosstalk to a temperature upto 0.33 με/ºC, while still providing a high strain sensitivity of ~25.6 pm}/με....

  7. Biased liquid crystal infiltrated photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Scolari, Lara;

    2009-01-01

    A simulation scheme for the transmission spectrum of a photonic crystal fiber infiltrated with a nematic liquid crystal and subject to an external bias is presented. The alignment of the biased liquid crystal is simulated using the finite element method to solve the relevant system of coupled...... partial differential equations. From the liquid crystal alignment the full tensorial dielectric permittivity in the capillaries is derived. The transmission spectrum for the photonic crystal fiber is obtained by solving the generalized eigenvalue problem deriving from Maxwell’s equations using a vector...... element based finite element method. We demonstrate results for a splay aligned liquid crystal infiltrated into the capillaries of a four-ring photonic crystal fiber and compare them to corresponding experiments....

  8. Compact and broadband waveguide taper based on partial bandgap photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Jin Hou; Dingshan Gao; Huaming Wu; Zhiping Zhou

    2009-01-01

    Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap. The photonic crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.

  9. Liquid Crystals and Photonic Bandgap Fiber Components

    DEFF Research Database (Denmark)

    Weirich, Johannes; Wei, Lei; Scolari, Lara;

    Liquid Crystal(LC)filled Photonic Crystal Fibers(PCFs) represent a promising platform for the design and the fabrication of tunable all-in fiber devices. Tunability is achieved by varying the refractive index of the LC thermally, optically or electrically. In this contribution we present important...

  10. Low Loss Plastic Terahertz Photonic Band-Gap Fibres

    Institute of Scientific and Technical Information of China (English)

    GENG You-Fu; TAN Xiao-Ling; ZHONG Kai; WANG Peng; YAO Jian-Quan

    2008-01-01

    We report a numerical investigation on terahertz wave propagation in plastic photonic band-gap fibres which are characterized by a 19-unit-cell air core and hexagonal air holes with rounded corners in cladding. Using the finite element method, the leakage loss and absorption loss are calculated and the transmission properties are analysed.The lowest loss of 0.268 dB/m is obtained. Numerical results show that the fibres could liberate the constraints of background materials beyond the transparency region in terahertz wave band, and efficiently minimize the effect of absorption by background materials, which present great advantage of plastic photonic band-gap fibres in long distance terahertz delivery.

  11. Treating temperature effect on bandgap in polymer opal photonic crystals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The optical reflective spectra and microstruc- tures of polystyrene opal photonic crystals treated with dif- ferent temperatures have been investigated. With tempera- ture increasing, the polystyrene spheres in opal structure transform to dodecahedrons, and the peak of reflective spec- trum moves to shorter wavelength. The experiment result testifies the effect of the effective refractive index and the filling ratio to the bandgap position, and it corresponds to the theoretical simulative result.

  12. Three-dimensional metallic photonic crystals with optical bandgaps.

    Science.gov (United States)

    Vasilantonakis, Nikos; Terzaki, Konstantina; Sakellari, Ioanna; Purlys, Vytautas; Gray, David; Soukoulis, Costas M; Vamvakaki, Maria; Kafesaki, Maria; Farsari, Maria

    2012-02-21

    The fabrication of fully three-dimensional photonic crystals with a bandgap at optical wavelengths is demonstrated by way of direct femtosecond laser writing of an organic-inorganic hybrid material with metal-binding moieties, and selective silver coating using electroless plating. The crystals have 600-nm intralayer periodicity and sub-100 nm features, and they exhibit well-defined diffraction patterns. PMID:22278944

  13. Waveguidance by the photonic bandgap effect in optical fibres

    DEFF Research Database (Denmark)

    Broeng, Jes; Søndergaard, Thomas; Barkou, Stig Eigil;

    1999-01-01

    Photonic crystals form a new class of intriguing building blocks to be utilized in future optoelectronics and electromagnetics. One of the most exciting possiblilties offered by phtonic crystals is the realization of new types of electromagnetic waveguides. In the optical domain, the most mature...... technology for such photonic bandgap (PBG) waveguides is in optical fibre configurations. These new fibres can be classified in a fundamentally different way to all optical waveguides and possess radically different guiding properties due to PBG guidance, as opposed to guidance by total internal refelction...

  14. Cavity quantum electrodynamics with three-dimensional photonic bandgap crystals

    CERN Document Server

    Vos, W L

    2015-01-01

    This paper gives an overview of recent work on three-dimensional (3D) photonic crystals with a "full and complete" 3D photonic band gap. We review five main aspects: 1) spontaneous emission inhibition, 2) spatial localization of light within a tiny nanoscale volume (aka "a nanobox for light"), 3) the introduction of a gain medium leading to thresholdless lasers, 4) breaking of the weak-coupling approximation of cavity QED, both in the frequency and in the time-domain, 5) decoherence, in particular the shielding of vacuum fluctuations by a 3D photonic bandgap. In addition, we list and evaluate all known photonic crystal structures with a demonstrated 3D band gap.

  15. A vector boundary matching technique for efficient and accurate determination of photonic bandgaps in photonic bandgap fibers.

    Science.gov (United States)

    Dong, Liang

    2011-06-20

    A vector boundary matching technique has been proposed and demonstrated for finding photonic bandgaps in photonic bandgap fibers with circular nodes. Much improved accuracy, comparing to earlier works, comes mostly from using more accurate cell boundaries for each mode at the upper and lower edges of the band of modes. It is recognized that the unit cell boundary used for finding each mode at band edges of the 2D cladding lattice is not only dependent on whether it is a mode at upper or lower band edge, but also on the azimuthal mode number and lattice arrangements. Unit cell boundaries for these modes are determined by mode symmetries which are governed by the azimuthal mode number as well as lattice arrangement due to mostly geometrical constrains. Unit cell boundaries are determined for modes at both upper and lower edges of bands of modes dominated by m = 1 and m = 2 terms in their longitudinal field Fourier-Bessel expansion series, equivalent to LP0s and LP1s modes in the approximate LP mode representations, for hexagonal lattice to illustrate the technique. The novel technique is also implemented in vector form and incorporates a transfer matrix algorithm for the consideration of nodes with arbitrary refractive index profiles. Both are desired new capabilities for further explorations of advanced new designs of photonic bandgap fibers. PMID:21716499

  16. Air-guiding photonic bandgap fiber with improved triangular air-silica photonic crystal cladding

    OpenAIRE

    Yan, M; Shum, P

    2005-01-01

    We introduce a small-core air-guiding photonic crystal fiber whose cladding is made of improved air-silica photonic crystal with non-circular air holes placed in triangular lattice. The fiber achieves un-disturbed bandgap guidance over 350nm wavelength range.

  17. Experimental investigation of hollow-core photonic crystal fibers with five photonic band-gaps

    Institute of Scientific and Technical Information of China (English)

    YUAN Jin-hui; HOU Lan-tian; WEI Dong-bin; WANG Hai-yun; ZHOU Gui-yao

    2008-01-01

    The hollow-core photonic crystal fibers (HC-PCFs) with integrity structure have been fabricated with an improved twice stack-and-draw technique. The transmission spectrum shows that five photonic band-gaps within 450-1100 nm have been obtained.And the green light transmission in the HC-PCFs'has been observed remarkably.

  18. One-dimensional photonic bandgap structure in abalone shell

    Institute of Scientific and Technical Information of China (English)

    LI Bo; ZHOU Ji; LI Longtu; LI Qi; HAN Shuo; HAO Zhibiao

    2005-01-01

    @@ Photonic bandgap (PBG) materials are periodic com- posites of dielectric materials in which electromagnetic waves of certain frequency range cannot propagate in any or a special direction. Recently, there has been great inter- est in synthetic PBG materials due to their ability in ma- nipulation of photons. Since 500 million years ago, the natural world has been exploiting photonic structures for specific biological purposes[1]. Different types of biologi- cal PBG materials have been discovered in recent years, such as the one-dimension PBG structure in the sea mouse Aphrodita[2], and the fruits Elaeocarpus[3,4]; two-dimension PBG structure in the male peacock Pavo muticus feathers[5], Indonesian male Papilio palinurus butterfly[6], Thaumantis diores butterfly[7] and the male Ancyluris meliboeus Fabricius butterflies[8]; and three-dimension PBG structure in the weevil Pachyrhynchus argus[9].

  19. The Second Order Guided Modes Based on Photonic Bandgap Effects in Air/Glass Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng

    2009-01-01

    We introduce a defect site in the periodic structure of a photonic bandgap fiber,to confine and guide the second order mode by photonic bandgap effects.Based on a high air-filling fraction photonic crystal cladding structure,a simplified model with an equivalent air cladding was proposed to explore and analyze the properties of this second order guided mode.

  20. INVESTIGATION ON VARIOUS DESIGN PARAMETERS WHICH AFFECT THE BANDGAP OF TWO DIMENSIONAL PHOTONIC CRYSTAL STRUCTURE

    OpenAIRE

    Anila Dhingra*, K. C. Roy, Govind Kumar

    2016-01-01

    An emerging element in optical fiber communication, 2D Photonic Crystal is an artificial periodic structure having a bandgap which shows a prohibition of a range of wavelengths to pass away through it. Various design parameters which affect the bandgap of 2D photonic crystal structure such as lattice structure, shape of rods, r/a ratio, dielectric constant etc. are studied in this paper. The Plane Wave Expansion (PWE) method is used to calculate the bandgap structure of two dimensional photon...

  1. True photonic band-gap mode-control in VCSEL structures

    DEFF Research Database (Denmark)

    Romstad, F.; Madsen, M.; Birkedal, Dan;

    2003-01-01

    Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect.......Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect....

  2. Bandgap isotropy in photonic quasicrystals with low-index contrast

    Science.gov (United States)

    Andreone, Antonello; Abbate, Giancarlo; Di Gennaro, Emiliano; Rose Thankamani, Priya

    2012-05-01

    Formation and development of the photonic band gap in two-dimensional 8-, 10-, and 12-fold symmetry quasicrystalline lattices of low-index contrast are reported. Finite-size structures made of dielectric cylindrical rods are studied and measured in the microwave region, and their properties are compared with a conventional hexagonal crystal. Band-gap characteristics are investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence are used to investigate the isotropic nature of the band gap.

  3. Soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2009-01-01

    The formation of solitons upon compression of linearly chirped pulses in hollow-core photonic bandgap fibers is investigated numerically. The dependence of soliton duration on the chirp and power of the input pulse and on the dispersion slope of the fiber is investigated, and the validity...... of an approximate scaling relation is tested. It is concluded that compression of input pulses of several ps duration and sub-MW peak power can lead to a formation of solitons with ∼100 fs duration and multi-megawatt peak powers. The dispersion slope of realistic hollow-core fibers appears to be the main obstacle...

  4. Liquid Crystal Photonic bandgap Fibers: Modeling and Devices

    DEFF Research Database (Denmark)

    Weirich, Johannes

    In this PhD thesis an experimental and numerical investigation of liquid crystal infiltrated photonic bandgap fibers (LCPBGs) is presented. A simulation scheme for modeling LCPBG devices including electrical tunability is presented. New experimental techniques, boundary coating and the applications...... of monomer added LCs, are investigated. Waveplates based on LCPBGs and a tunable polarization maintaining filter are developed. An on-chip tunable notch filter based on long period gratings is presented. Furthermore, the application of a LCPBG device for the electrical control of a fiber laser is...

  5. Electrically controllable liquid crystal photonic bandgap fiber with dual-frequency control

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Riishede, Jesper;

    2005-01-01

    We present an electrically tunable liquid crystal photonic bandgap fiber device based on a dual frequency liquid crystal with pre-tilted molecules that allows the bandgaps to be continuously tuned. The frequency dependent behavior of the liquid crystal enables active shifting of the bandgaps toward...

  6. Novel spatial solitons in light-induced photonic bandgap structures

    Institute of Scientific and Technical Information of China (English)

    Ci-bo LOU; Li-qin TANG; Dao-hong SONG; Xiao-sheng WANG; Jing-jun XU; Zhi-gang CHEN

    2008-01-01

    The study of wave propagation in periodic sys-tems is at the frontiers of physics, from fluids to condensed matter physics, and from photonic crystals to Bose-Einstein condensates. In optics, a typical example of periodic system is a closely-spaced waveguide array, in which collective behavior of wave propagation exhibits many intriguing phenomena that have no counterpart in homogeneous media. Even in a linear waveguide array, the diffraction property of a light beam changes due to evanescent coupling between nearby waveguide sites, leading to normal and anomalous discrete diffraction. In a nonlinear waveguide array, a bal-ance between diffraction and self-action gives rise to novel localized states such as spatial "discrete solitons" in the semi-infinite (or total-internal-reflection) gap or spatial "gap solitons" in the Bragg reflection gaps, Recently, in a series of experiments, we have "fabricated" closely-spaced waveguide arrays (photonic lattices) by optical induction. Such photonic structures have attracted great interest due to their novel physics, link to photonic crystals, as well as po-tential applications in optical switching and navigation. In this review article, we present a brief overview on our ex-perimental demonstrations of a number of novel spatial soliton phenomena in light-induced photonic bandgap structures, including self-trapping of fundamental discrete solitons and more sophisticated lattice gap solitons. Much of our work has direct impact on the study of similar discrete phenomena in systems beyond optics, including sound waves, water waves, and matter waves (Bose-Einstein con-densates) propagating in periodic potentials.

  7. Enhanced Two-Photon Absorption in a Hollow-Core Photonic Bandgap Fiber

    CERN Document Server

    Saha, Kasturi; Londero, Pablo; Gaeta, Alexander L

    2010-01-01

    We show that two-photon absorption (TPA) in Rubidium atoms can be greatly enhanced by the use of a hollow-core photonic bandgap fiber. We investigate off-resonant, degenerate Doppler-free TPA on the 5S1/2 - 5D5/2 transition and observe 1% absorption of a pump beam with a total power of only 1 mW in the fiber. These results are verified by measuring the amount of emitted blue fluorescence and are consistent with the theoretical predictions which indicate that transit time effects play an important role in determining the two-photon absorption cross-section in a confined geometry.

  8. High Thermal and Electrical Tunability of Negative Dielectric Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Scolari, Lara; Weirich, Johannes;

    2008-01-01

    We infiltrate photonic crystal fibers with negative dielectric liquid crystals. 400nm bandgap shift is obtained in the range 22ºC-80ºC and 119nm shift of the long-wavelength bandgap edge is achieved by applying a voltage of 200V.......We infiltrate photonic crystal fibers with negative dielectric liquid crystals. 400nm bandgap shift is obtained in the range 22ºC-80ºC and 119nm shift of the long-wavelength bandgap edge is achieved by applying a voltage of 200V....

  9. Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard;

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used to...

  10. Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers

    DEFF Research Database (Denmark)

    Shirakawa, A.; Chen, M.; Suzuki, Y.;

    2014-01-01

    Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot. Multicore fiber lasers are a promising tool for power scaling by coherent beam combination. © 2014 OSA....

  11. Photonic bandgap structures for guiding of long-range surface plasmon polaritons

    DEFF Research Database (Denmark)

    Leosson, K.; Nikolajsen, T.; Boltasseva, Alexandra;

    2003-01-01

    We present the first observations of long-range plasmon polariton guiding in photonic bandgap structures. The transmission of waveguide structures is characterized at telecommunication wavelengths and a propagation loss below 4 dB/mm is determined.......We present the first observations of long-range plasmon polariton guiding in photonic bandgap structures. The transmission of waveguide structures is characterized at telecommunication wavelengths and a propagation loss below 4 dB/mm is determined....

  12. Broadband orbital angular momentum transmission using a hollow-core photonic bandgap fiber.

    Science.gov (United States)

    Li, Haisu; Ren, Guobin; Lian, Yudong; Zhu, Bofeng; Tang, Min; Zhao, Yuanchu; Jian, Shuisheng

    2016-08-01

    We present the viability of exploiting a current hollow-core photonic bandgap fiber (HC-PBGF) to support orbital angular momentum (OAM) states. The photonic bandgap intrinsically provides a large refractive index spacing for guiding light, leading to OAM transmission with low crosstalk. From numerical simulations, a broad OAM±1 mode transmission window with satisfied effective index separations between vector modes (>10-4) and low confinement loss (communication harnessing OAM multiplexing.

  13. Low loss liquid crystal photonic bandgap fiber in the near-infrared region

    DEFF Research Database (Denmark)

    Scolari, Lara; Wei, Lei; Gauza, S.;

    2010-01-01

    We infiltrate a photonic crystal fiber with a perdeuterated liquid crystal, which has a reduced infrared absorption. The lowest loss ever reported (about 1 dB) in the middle of the near-infrared bandgap is achieved.......We infiltrate a photonic crystal fiber with a perdeuterated liquid crystal, which has a reduced infrared absorption. The lowest loss ever reported (about 1 dB) in the middle of the near-infrared bandgap is achieved....

  14. Robustness of One-Dimensional Photonic Bandgaps Under Random Variations of Geometrical Parameters

    CERN Document Server

    Sozuer, H S

    2005-01-01

    The supercell method is used to study the variation of the photonic bandgaps in one-dimensional photonic crystals under random perturbations to thicknesses of the layers. The results of both plane wave and analytical band structure and density of states calculations are presented along with the transmission cofficient as the level of randomness and the supercell size is increased. It is found that higher bandgaps disappear first as the randomness is gradually increased. The lowest bandgap is found to persist up to a randomness level of 55 percent.

  15. Photonic Bandgap Properties of Atom-lattice Photonic Crystals in Polymer

    Institute of Scientific and Technical Information of China (English)

    REN Lin; WANG Dian; SUN Gui-ting; NIU Li-gang; YANG Han; SONG Jun-feng

    2011-01-01

    The present paper covers the various photonic crystals(PhCs) structures mimicking real atom-lattice structures in electronic crystals by using the femtosecond laser-induced two-photon photopolymerization of SU-8 resin. The bandgap properties were investigated by varying the crystal orientations in <111>, <110> and <100> of diamond-lattice PhCs. lhe photonic stop gaps were present at λ=3.88 μm in <111> direction, λ=4.01 μtm in <110> direction and λ=5.30 μm in <100> direction, respectively. In addition, defects were introduced in graphite-lattice PhCs and the strong localization of photons in this structure with defects at λ=5 μm was achieved. All the above work shows the powerful capability of femtosecond laser fabrication in manufacturing various complicated threedimensional photonic crystals and of controlling photons by inducing defects in the PhCs samples.

  16. Highly tunable large core single-mode liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper; Bjarklev, Anders Overgaard;

    2006-01-01

    We demonstrate a highly tunable photonic bandgap fiber, which has a large-core diameter of 25 mu m and an effective mode area of 440 mu m(2). The tunability is achieved by infiltrating the air holes of a photonic crystal fiber with an optimized liquid-crystal mixture having a large temperature...... Society of America....

  17. Computational methods for the analysis and design of photonic bandgap structures

    OpenAIRE

    Qiu, Min

    2000-01-01

    In the present thesis, computational methods for theanalysis and design of photonic bandgap structure areconsidered. Many numerical methods have been used to study suchstructures. Among them, the plane wave expansion method is veryoften used. Using this method, we show that inclusions ofelliptic air holes can be used effectively to obtain a largercomplete band gap for two-dimensional (2D) photonic crystals.An optimal design of a 2D photonic crystal is also consideredin the thesis using a comb...

  18. Mode areas and field energy distribution in honeycomb photonic bandgap fibers

    CERN Document Server

    Laegsgaard, J; Bjarklev, A; Laegsgaard, Jesper; Mortensen, Niels Asger; Bjarklev, Anders

    2003-01-01

    The field energy distributions and effective mode areas of silica-based photonic bandgap fibers with a honeycomb airhole structure in the cladding and an extra airhole defining the core are investigated. We present a generalization of the common effective area definition, suitable for the problem at hand, and compare the results for the photonic bandgap fibers with those of index-guiding microstructured fibers. While the majority of the field energy in the honeycomb photonic bandgap fibers is found to reside in the silica, a substantial fraction (up to ~30%) can be located in the airholes. This property may show such fibers particularly interesting for sensor applications, especially those based on nonlinear effects or interaction with other structures (e.g. Bragg gratings) in the glass.

  19. Compact optically-fed microwave true-time delay using liquid crystal photonic bandgap fiber device

    DEFF Research Database (Denmark)

    Wei, Lei; Xue, Weiqi; Chen, Yaohui;

    2009-01-01

    Electrically tunable liquid crystal photonic bandgap fiber device based optically-fed microwave true-time delay is demonstrated. A maximum ~60° phase shift and an averaged ~7.2ps true time delay are obtained over the modulation frequency range 1GHz-19GHz.......Electrically tunable liquid crystal photonic bandgap fiber device based optically-fed microwave true-time delay is demonstrated. A maximum ~60° phase shift and an averaged ~7.2ps true time delay are obtained over the modulation frequency range 1GHz-19GHz....

  20. Tunable All-in-Fiber Waveplates Based on Negative Dielectric Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Eskildsen, Lars; Weirich, Johannes;

    2008-01-01

    Tunable all-in-fiber waveplates based on negative dielectric liquid crystal photonic bandgap fibers are presented. The birefringence can be tuned electrically and thermally to work as a quarter-wave or a half-wave plate in the range 1520 nm-1580 nm.......Tunable all-in-fiber waveplates based on negative dielectric liquid crystal photonic bandgap fibers are presented. The birefringence can be tuned electrically and thermally to work as a quarter-wave or a half-wave plate in the range 1520 nm-1580 nm....

  1. Three-dimensional single gyroid photonic crystals with a mid-infrared bandgap

    CERN Document Server

    Peng, Siying; Chen, Valerian H; Khabiboulline, Emil T; Braun, Paul; Atwater, Harry A

    2016-01-01

    A gyroid structure is a distinct morphology that is triply periodic and consists of minimal isosurfaces containing no straight lines. We have designed and synthesized amorphous silicon (a-Si) mid-infrared gyroid photonic crystals that exhibit a complete bandgap in infrared spectroscopy measurements. Photonic crystals were synthesized by deposition of a-Si/Al2O3 coatings onto a sacrificial polymer scaffold defined by two-photon lithography. We observed a 100% reflectance at 7.5 \\mum for single gyroids with a unit cell size of 4.5 \\mum, in agreement with the photonic bandgap position predicted from full-wave electromagnetic simulations, whereas the observed reflection peak shifted to 8 um for a 5.5 \\mum unit cell size. This approach represents a simulation-fabrication-characterization platform to realize three-dimensional gyroid photonic crystals with well-defined dimensions in real space and tailored properties in momentum space.

  2. Band structure of germanium carbides for direct bandgap silicon photonics

    Science.gov (United States)

    Stephenson, C. A.; O'Brien, W. A.; Penninger, M. W.; Schneider, W. F.; Gillett-Kunnath, M.; Zajicek, J.; Yu, K. M.; Kudrawiec, R.; Stillwell, R. A.; Wistey, M. A.

    2016-08-01

    Compact optical interconnects require efficient lasers and modulators compatible with silicon. Ab initio modeling of Ge1-xCx (x = 0.78%) using density functional theory with HSE06 hybrid functionals predicts a splitting of the conduction band at Γ and a strongly direct bandgap, consistent with band anticrossing. Photoreflectance of Ge0.998C0.002 shows a bandgap reduction supporting these results. Growth of Ge0.998C0.002 using tetrakis(germyl)methane as the C source shows no signs of C-C bonds, C clusters, or extended defects, suggesting highly substitutional incorporation of C. Optical gain and modulation are predicted to rival III-V materials due to a larger electron population in the direct valley, reduced intervalley scattering, suppressed Auger recombination, and increased overlap integral for a stronger fundamental optical transition.

  3. Bandgaps of the Chalcogenide Glass Hollow-Core Photonic Crystal Fiber

    International Nuclear Information System (INIS)

    Bandgaps of chalcogenide glass hollow-core photonic crystal fibers (GLS HC-PCFs) are analyzed by using the plane-wave expansion method. A mid-infrared laser can propagate in these low confinement loss fibers when the wavelength falls into the bandgaps. For enlarging the bandgap width, an improved GLS HC-PCF is put forward, the normalized frequency kΛ of the improved fiber is from 7.2 to 8.5 in its first bandgap. The improved GLS HC-PCF with pitch of 4.2 μm can transmit the lights with wavelengths ranging from 3.1 μm to 3.7 μm. (fundamental areas of phenomenology(including applications))

  4. Cavity quantum electrodynamics with three-dimensional photonic bandgap crystals

    NARCIS (Netherlands)

    Vos, W.L.; Woldering, L.A.; Ghulinyan, M.; Pavesi, L.

    2015-01-01

    This paper is Chapter 8 of the book "Light Localisation and Lasing: Random and Pseudorandom Photonic Structures", edited by Mher Ghulinyan and Lorenzo Pavesi (Cambridge University Press, Cambridge, 2015). It provides an overview of much recent work on 3D photonic crystals with a complete photonic b

  5. Low index-contrast aperiodically ordered photonic quasicrystals for the development of isotropic photonic band-gap devices

    Science.gov (United States)

    Priya Rose, T.; Di Gennaro, E.; Andreone, A.; Abbate, G.

    2010-05-01

    Photonic quasicrystals (PQCs) have neither true periodicity nor translational symmetry, however they can exhibit symmetries that are not achievable by conventional periodic structures. The arbitrarily high rotational symmetry of these materials can be practically exploited to manufacture isotropic band gap materials, which are perfectly suitable for hosting waveguides or cavities. In this work, formation and development of the photonic bandgap (PBG) in twodimensional 8-, 10- and 12-fold symmetry quasicrystalline lattices of low dielectric contrast (0.4-0.6) were measured in the microwave region and compared with the PBG properties of a conventional hexagonal crystal. Band-gap properties were also investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence from 0° to 30° were used in order to investigate the isotropic nature of the band-gap.

  6. Analysis of photonic band-gap (PBG) structures using the FDTD method

    DEFF Research Database (Denmark)

    Tong, M.S.; Cheng, M.; Lu, Y.L.;

    2004-01-01

    In this paper, a number of photonic band-gap (PBG) structures, which are formed by periodic circuit elements printed oil transmission-line circuits, are studied by using a well-known numerical method, the finite-difference time-domain (FDTD) method. The results validate the band-stop filter...

  7. Generation of Low Divergent High Power Supercontinuum Through a Large Mode Area Photonic Bandgap Fiber

    CERN Document Server

    Ghosh, S; Varshney, R K; Pal, B P

    2012-01-01

    We report generation of broadband low divergent supercontinuum over the entire wavelength window of 1.5 to 3.5 {\\mu}m from a 2.25 meter long effective single moded photonic bandgap fiber with mode area of 1100 {\\mu}m2.

  8. 10 Gbit/s transmission over air-guiding photonic bandgap fibre at 1550 nm

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Zsigri, Beata; Hansen, T.P.;

    2005-01-01

    The first data transmission over air-guiding photonic bandgap (PBG) fibre is demonstrated. A 10 Gbit/s signal was successfully transmitted at 1550 nm over 150 m of singlemode PBG fibre, thus demonstrating their applicability to optical communications. Furthermore, the impact of the polarisation...

  9. 30W, 1178nm Yb-doped photonic bandgap fiber amplifier

    DEFF Research Database (Denmark)

    Shirakawa, Akira; Maruyama, Hiroki; Ueda, Ken-ichi;

    2009-01-01

    High-power, high-efficiency ytterbium-doped solid-core photonic-bandgap fiber amplification at the long-wavelength edge of the Yb gain band is reported. Amplified-spontaneous-emission-free, 30W nonpolarized and 25W linearly-polarized 1178nm outputs have been achieved with

  10. Reflection-induced bias error in an air-core photonic bandgap fiber optic gyroscope.

    Science.gov (United States)

    Zhang, Zuchen; Xu, Xiaobin; Zhang, Zhihao; Song, Ningfang; Zhang, Chunxi

    2016-01-15

    Analysis of the bias error induced by reflections in an air-core photonic bandgap fiber gyroscope is performed by both simulation and experiment. The bias error is sinusoidally periodic under modulation, and its intensity is related to the relative positions of the reflection points. A simple and effective method for the suppression of the error is proposed, and it has been verified experimentally.

  11. Transmission Bandwidth Tunability of a Liquid-Filled Photonic Bandgap Fiber

    Institute of Scientific and Technical Information of China (English)

    ZOU Bing; LIU Yan-Ge; DU Jiang-Sing; WANG Zhi; HAN Ting-Ting; XU Jian-Bo; LI Yuan; LIU Bo

    2009-01-01

    @@ A temperature tunable photonic bandgap tiber (PBGF) is demonstrated by an index-guiding photonic crystal fiber filled with high-index liquid. The temperature tunable characteristics of the fiber axe experimentally and numerically investigated. Compression of transmission bandwidth of the PBGF is demonstrated by changing the temperature of part of the fiber. The tunable transmission bandwidth with a range of 250 nm is achieved by changing the temperature from 30℃ to 90℃.

  12. Study on the photonic bandgaps of hollow-core microstructured fibers

    Institute of Scientific and Technical Information of China (English)

    Zhaolun Liu; Guiyao Zhou; Lantian Hou

    2006-01-01

    A simple method is presented to measure the transmission spectrum of hollow-core microstructured fibers in the visible, near-infrared, and mid-infrared regions. The plane wave expansion method is applied to analyze the photonic bandgaps of hollow-core microstructured fibers. The experimental results indicate that there are several strong transmission bands in the near-infrared and mid-infrared region, but hardly any transmission phenomena in the visible region, which shows that there are some bandgaps in nearinfrared wavelength. The experimental results are consistent with the numerically simulative results using a plane wave expansion method.

  13. Manipulating the Propagation of Solitons with Solid-Core Photonic Bandgap Fibers

    Directory of Open Access Journals (Sweden)

    O. Vanvincq

    2012-01-01

    Full Text Available We review the dynamics of soliton self-frequency shift induced by Raman gain in special solid-core photonic bandgap fibers and its consequences in terms of supercontinuum generation. These photonic bandgap fibers have been designed to allow nonlinear experiments in the first bandgap without suffering from significant loss even when working close to the photonic bandgap edge. We studied experimentally, numerically, and analytically the extreme deceleration of the soliton self-frequency shift at the long-wavelength edge of the first transmission window. This phenomenon is interpreted as being due to a large variation of the group-velocity dispersion in this spectral range and has been obtained with no significant power loss. Then, we investigated experimentally and numerically the generation of supercontinuum in this kind of fibers, in both spectral and temporal domains. In particular, we demonstrated an efficient tailoring of the supercontinuum spectral extension as well as a strong noise reduction at its long-wavelength edge.

  14. Effect of photonic bandgap on upconversion emission in YbPO4:Er inverse opal photonic crystals.

    Science.gov (United States)

    Yang, Zhengwen; Zhu, Kan; Song, Zhiguo; Zhou, Dacheng; Yin, Zhaoyi; Qiu, Jianbei

    2011-01-20

    We obtained upconversion (UC) light-emitting photonic materials (YbPO(4):Er) with an inverse opal structure by the self-assembly technique in combination with a solgel method. The effect of the photonic stopband on the UC luminescence of the (2)H(11/2), (4)S(3/2)→(4)I(15/2), and (4)F(9/2)→(4)I(15/2) transitions of Er(3+) has been observed in the inverse opals of the Er(3+)-doped YbPO(4). Significant suppression of the UC emission was detected if the photonic bandgap overlapped with the Er(3+) ions emission band, while enhancement of the UC emission occurs if the emission band appears at the edge of the bandgap. PMID:21263723

  15. First Evidence of Near-Infrared Photonic Bandgap in Polymeric Rod-Connected Diamond Structure

    CERN Document Server

    Chen, Lifeng; Zheng, Xu; Lin, Jia-De; Oulton, Ruth; Lopez-Garcia, Martin; Ho, Ying-Lung D; Rarity, John G

    2015-01-01

    We present the simulation, fabrication, and optical characterization of low-index polymeric rod-connected diamond (RCD) structures. Such complex three-dimensional photonic crystal structures are created via direct laser writing by two-photon polymerization. To our knowledge, this is the first measurement at near-infrared wavelengths, showing partial photonic bandgaps. We characterize structures in transmission and reflection using angular resolved Fourier image spectroscopy to visualize the band structure. Comparison of the numerical simulations of such structures with the experimentally measured data show good agreement for both P- and S-polarizations.

  16. THz Photonic Band-Gap Prisms Fabricated by Fiber Drawing

    DEFF Research Database (Denmark)

    Busch, Stefan F.; Xu, Lipeng; Stecher, Matthias;

    2012-01-01

    We suggest a novel form of polymeric based 3D photonic crystal prisms for THz frequencies which could be fabricated using a standard fiber drawing technique. The structures are modeled and designed using a finite element analyzing technique. Using this simulation software we theoretically study...

  17. Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Scolari, Lara; Weirich, Johannes;

    2008-01-01

    A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at X=1364nm with a bandwidth (FWHM) of 237nm. Tunability is achieved by changing the temperature of the filter. A shift of 210nm of the central wavelength has been observed...

  18. Broadband orbital angular momentum transmission using a hollow-core photonic bandgap fiber.

    Science.gov (United States)

    Li, Haisu; Ren, Guobin; Lian, Yudong; Zhu, Bofeng; Tang, Min; Zhao, Yuanchu; Jian, Shuisheng

    2016-08-01

    We present the viability of exploiting a current hollow-core photonic bandgap fiber (HC-PBGF) to support orbital angular momentum (OAM) states. The photonic bandgap intrinsically provides a large refractive index spacing for guiding light, leading to OAM transmission with low crosstalk. From numerical simulations, a broad OAM±1 mode transmission window with satisfied effective index separations between vector modes (>10-4) and low confinement loss (power weight for OAM mode) is found to be affected by the modal effective area. Simulation results also show HC-PBGF based OAM transmission is immune to fabrication inaccuracies near the hollow core. This work illustrates that HC-PBGF is a competitive candidate for high-capacity communication harnessing OAM multiplexing. PMID:27472626

  19. Investigation of residual core ellipticity induced nonreciprocity in air-core photonic bandgap fiber optical gyroscope.

    Science.gov (United States)

    Xu, Xiaobin; Zhang, Zuchen; Zhang, Zhihao; Jin, Jing; Song, Ningfang

    2014-11-01

    Air-core photonic bandgap fiber (PBF) is an excellent choice for fiber optic gyroscope owing to its incomparable adaptability of environment. Strong and continuous polarization mode coupling is found in PBFs with an average intensity of ~-30 dB, but the coupling arrives at the limit when the maximum optical path difference between the primary waves and the polarization-mode-coupling-induced secondary waves reaches ~10mm, which is corresponding to the PBF length of ~110 m according to the birefringence in the PBF. Incident light with the low extinction ratio (ER) can suppress the birth of the polarization-mode-coupling-induced secondary waves, but the low-ER light obtained by the conventional Lyot depolarizers does not work here. Consequently, a large nonreciprocity and a bias error of ~13°/h are caused in the air-core photonic bandgap fiber optical gyroscope (PBFOG) with a PBF coil of ~268 m.

  20. Picosecond pump-probe measurement of bandgap changes in SiO2/TiO2 one-dimensional photonic bandgap structures

    Science.gov (United States)

    Hwang, Jisoo; Kim, Min Jung; Wu, J. W.; Mook Lee, Seung; Rhee, Bum Ku

    2006-02-01

    A picosecond pump-probe nonlinear optical measurement is performed in SiO2/TiO2 one-dimensional photonic bandgap structures fabricated by a solgel method. Both high and low band edges were examined by varying the probe wavelengths and angle tuning was also employed to further clarify the mechanism of a nonlinear optical response. The third-order nonlinear optical response in one-dimensional photonic bandgap structures that comprise TiO2 films is responsible for the nonlinear optical transmissions at both bandgap edges, with an 8% decrease at the low-energy edge and a 4.5% increase at the high-energy edge for a 355 nm pump intensity of 430 MW/cm2.

  1. Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier

    OpenAIRE

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Scolari, Lara; Broeng, Jes

    2011-01-01

    Enabling Single-Mode (SM) operation in Large-Mode-Area (LMA) fiber amplifiers and lasers is critical, since a SM output ensures high beam quality and excellent pointing stability. In this paper, we demonstrate and test a new design approach for achieving SM LMA rod fibers by using a photonic bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performan...

  2. Transparency and Strong Gain Without Population Inversion in Photonic Bandgap Crystals

    Institute of Scientific and Technical Information of China (English)

    杜春光; 胡正峰; 侯春风; 李师群

    2002-01-01

    Without using the weak-field approximation, we investigate the transient properties of a Λ-type atom with one transition near resonant with a photonic bandgap edge. Whatever the initial state of the atom is, the atom can become transparent to a probefield, and strong gain without population inversion is also possible if the atom has been pre-excited. The defect mode formed by atomic doping can have a strong effect on the absorption properties of the atom.

  3. Continuous generation of Rubidium vapor in hollow-core photonic band-gap fibers

    CERN Document Server

    Donvalkar, Prathamesh S; Clemmen, Stephane; Gaeta, Alexander L

    2015-01-01

    We demonstrate high optical depths (50+/-5), lasting for hours in Rubidium-filled hollow-core photonic band-gap fibers, which represents a 1000X improvement over operation times previously reported. We investigate the vapor generation mechanism using both a continuous-wave and a pulsed light source and find that the mechanism for generating the Rubidium atoms is primarily due to thermal vaporization. Continuous generation of large vapor densities should enable measurements at the single-photon level by averaging over longer time scales.

  4. All-optical modulation in dye-doped nematic liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper; Bjarklev, Anders Overgaard;

    2004-01-01

    Photonic crystal fibers (PCFs) have attracted significant attention during the last years and much research has been devoted to develop fiber designs for various applications, hereunder tunable fiber devices. Recently, thermally and electrically tunable PCF devices based on liquid crystals (LCs......) have been demonstrated. However, optical tuning of the LC PCF has until now not been demonstrated. Here we demonstrate an all-optical modulator, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid...

  5. On the spectrum of waveguides in planar photonic bandgap structures

    CERN Document Server

    Brown, Malcolm; Plum, Michael; Wood, Ian

    2012-01-01

    We study a Helmholtz-type spectral problem related to the propagation of electromagnetic waves in photonic crystal waveguides. The waveguide is created by introducing a linear defect into a two-dimensional periodic medium. The defect is infinitely extended and aligned with one of the coordinate axes. The perturbation is expected to introduce guided mode spectrum inside the band gaps of the fully periodic, unperturbed spectral problem. In the first part of the paper, we prove that, somewhat unexpectedly, guided mode spectrum can be created by arbitrarily "small" perturbations. Secondly we show that, after performing a Floquet decomposition in the axial direction of the waveguide, for any fixed value of the quasi-momentum $k_x$ the perturbation generates at most finitely many new eigenvalues inside the gap.

  6. Non-resonant below-bandgap two-photon absorption in quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tian; Dagenais, Mario, E-mail: dage@ece.umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2015-04-27

    We study the optically nonlinear sub-bandgap photocurrent generation facilitated by an extended tailing distribution of states in an InAs/GaAs quantum dots (QDs) solar cell. The tailing states function as both the energy states for low energy photon absorption and the photocarriers extraction pathway. One of the biggest advantages of our method is that it can clearly differentiate the photocurrent due to one-photon absorption (1PA) process and two-photon absorption (2PA) process. Both 1PA and 2PA photocurrent generation efficiency in an InAs/GaAs QD device operated at 1550 nm have been quantitatively evaluated. A two-photon absorption coefficient β = 5.7 cm/GW is extracted.

  7. Micro-displacement sensors based on plastic photonic bandgap Bragg fibers

    CERN Document Server

    Qu, H; Bergeron, F; Olesik, J; Skorobogatiy, M

    2013-01-01

    We demonstrate an amplitude-based micro-displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a regular multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to presence of mode stripper in the form of the multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be smaller than 5 um for displacement sensing.

  8. Broadband optically controlled switching effect in a microfluid-filled photonic bandgap fiber

    Science.gov (United States)

    Guo, Junqi; Liu, Yan-ge; Wang, Zhi; Luo, Mingming; Huang, Wei; Han, Tingting; Liu, Xiaoqi

    2016-05-01

    Broadband optically controlled switching in a microfluid-filled photonic bandgap fiber (MF-PBGF) was observed and investigated. The MF-PBGF was formed by infusing a temperature-sensitive high-index fluid into all of the cladding holes of a microstructured optical fiber (MOF). The fiber was then side pumped with a 532 nm continuous wave laser. An extinction ratio of greater than 20 dB at most of the bandgap wavelengths (more than 200 nm) was obtained with a switching power of ∼147 mW. Theoretical and experimental investigations revealed that the effect originated from changes in the temperature gradient induced by heat absorption of the fiber coating with laser illumination. These investigations offer a new and simple approach to achieve wideband and flexible all-optical fiber switching devices without using any photosensitive materials.

  9. Below-bandgap second harmonic generation in GaAs photonic crystal cavites in (111)B and (001) crystal orientations

    CERN Document Server

    Buckley, Sonia; Petykiewicz, Jan; Lagoudakis, Konstantinos G; Kang, Ju-Hyung; Brongersma, Mark; Biermann, Klaus; Vuckovic, Jelena

    2014-01-01

    We demonstrate second harmonic generation in photonic crystal cavities in (001) and (111)B oriented GaAs. The fundamental resonance is at 1800 nm, leading to second harmonic below the GaAs bandgap. Below-bandgap operation minimizes absorption of the second harmonic and two photon absorption of the pump. Photonic crystal cavities were fabricated in both orientations at various in-plane rotations of the GaAs substrate. The rotation dependence and farfield patterns of the second harmonic match simulation. We observe similar maximum efficiencies of 1.2 %/W in (001) and (111)B oriented GaAs.

  10. Microstructured and Photonic Bandgap Fibers for Applications in the Resonant Bio- and Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Maksim Skorobogatiy

    2009-01-01

    Full Text Available We review application of microstructured and photonic bandgap fibers for designing resonant optical sensors of changes in the value of analyte refractive index. This research subject has recently invoked much attention due to development of novel fiber types, as well as due to development of techniques for the activation of fiber microstructure with functional materials. Particularly, we consider two sensors types. The first sensor type employs hollow core photonic bandgap fibers where core guided mode is confined in the analyte filled core through resonant effect in the surrounding periodic reflector. The second sensor type employs metalized microstructured or photonic bandgap waveguides and fibers, where core guided mode is phase matched with a plasmon propagating at the fiber/analyte interface. In resonant sensors one typically employs fibers with strongly nonuniform spectral transmission characteristics that are sensitive to changes in the real part of the analyte refractive index. Moreover, if narrow absorption lines are present in the analyte transmission spectrum, due to Kramers-Kronig relation this will also result in strong variation in the real part of the refractive index in the vicinity of an absorption line. Therefore, resonant sensors allow detection of minute changes both in the real part of the analyte refractive index (10−6–10−4 RIU, as well as in the imaginary part of the analyte refractive index in the vicinity of absorption lines. In the following we detail various resonant sensor implementations, modes of operation, as well as analysis of sensitivities for some of the common transduction mechanisms for bio- and chemical sensing applications. Sensor designs considered in this review span spectral operation regions from the visible to terahertz.

  11. Scattering loss analysis and structure optimization of hollow-core photonic bandgap fiber

    Science.gov (United States)

    Song, Jingming; Wu, Rong; Sun, Kang; Xu, Xiaoliang

    2016-06-01

    Effects of core structure in 7 cell hollow-core photonic bandgap fibers (HC-PBGFs) on scattering loss are analyzed by means of investigating normalized interface field intensity. Fibers with different core wall thickness, core radius and rounding corner of air hole are simulated. Results show that with thick core wall and expanded core radius, scattering loss could be greatly reduced. The scattering loss of the HC-PBGFs in the wavelength range of 1.5-1.56 μm could be decreased by about 50 % of the present level with optimized core structure design.

  12. Grating solitons near the photonic bandgap of a fiber Bragg grating

    Energy Technology Data Exchange (ETDEWEB)

    Senthilnathan, K. [Photonics Research Center and Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Kong (China); Ramesh Babu, P. [Department of Physics, Vellore Institute of Technology, Deemed University, Vellore 632014 (India); Porsezian, K. [Department of Physics, Pondicherry University, Pondicherry 605014 (India)]. E-mail: porsz@hotmail.com; Santhanam, V. [Department of Physics, Presidency College, University of Madras, Chennai 600005 (India); Gnanasekaran, S. [Department of Physics, Anna University, Chennai 600025 (India)

    2007-07-15

    In this paper, we consider the nonlinear pulse propagation through a fiber Bragg grating (FBG) structure wherein the nonlinearity includes both cubic and quintic effects. We study theoretically the formation of bright grating solitons in such a FBG when the carrier frequency of a nonlinear laser pulse is detuned out of the proper edge of the photonic bandgap (PBG). By using multiple scale analysis, we investigate the generation of the bright soliton near the PBG with the higher order linear and nonlinear effects. We also study the impact of quintic nonlinearity on the dispersion curves by deriving the nonlinear dispersion relation from the governing equations.

  13. Low index-contrast photonic bandgap fiber for transmission of short pulsed light

    DEFF Research Database (Denmark)

    Riishede, Jesper; Lægsgaard, Jesper; Broeng, Jes;

    2004-01-01

    The use of low-index-contrast photonic bandgap (PBG) fiber for transmission of short pulsed light is discussed. PBG fibers have positive waveguide dispersion at long wavelengths at which conventional index-guiding fibers have negative waveguide dispersion. PBG fibers with low-index contrast can...... be used to obtain fibers with zero dispersion and a large mode area below 800 nm$+3$/. The results show that the PBG fiber is less sensitive to nonlinear effects and allows transmission of considerably larger intensities....

  14. Metallic Photonic Bandgap Resonant Antennas with High Directivity and High Radiation Resistance

    Institute of Scientific and Technical Information of China (English)

    林青春; 符建; 何赛灵; 章坚武

    2002-01-01

    A metallic photonic bandgap (MPBG) resonant antenna is introduced, which has novel characteristics (such as high directivity and high radiation resistance for a certain range of frequencies) as compared to conventional MPBG antennas. The linear MPBG resonant antenna is formed by infinitely long metallic rods in vacuum. The numerical results for the radiation pattern and the radiation resistance are presented. By adjusting the struct ure of the MPBG resonant antenna and its working frequency, an optimal structure is achieved. The physical reasons for the novel characteristics of the MPBG resonant antenna are also explained.

  15. Thermally tunable bandgaps in a hybrid As2S3/silica photonic crystal fiber

    DEFF Research Database (Denmark)

    Markos, Christos; Stefani, Alessio; Bang, Ole

    2015-01-01

    We report the fabrication and characterization of a hybrid silica photonic crystal fiber (PCF) with integrated chalcogenide glass layers and we show how the bandgaps of the fiber can be thermally tuned. The formation of the high-index chalcogenide films on the inner surface of the PCF holes...... revealed resonances as strong as similar to 35 dB both in the visible and infrared regime. Temperature measurements indicate that the transmission windows can be tuned with a sensitivity as high as similar to 3.5 nm/degrees C. The proposed fiber has potential for all-fiber filtering and temperature sensing....

  16. Waveguiding and bending modes in a plasma photonic crystal bandgap device

    Directory of Open Access Journals (Sweden)

    B. Wang

    2016-06-01

    Full Text Available Waveguiding and bending modes are investigated in a fully tunable plasma photonic crystal. The plasma device actively controls the propagation of free space electromagnetic waves in the S to X band of the microwave spectrum. An array of discharge plasma tubes form a square crystal lattice exhibiting a well-defined bandgap, with individual active switching of the plasma elements to allow for waveguiding and bending modes to be generated dynamically. We show, through simulations and experiments, the existence of transverse electric (TE mode waveguiding and bending modes.

  17. Photolithography of thick photoresist coating for electrically controlled liquid crystal photonic bandgap fibre devices

    DEFF Research Database (Denmark)

    Wei, Lei; Khomtchenko, Elena; Alkeskjold, Thomas Tanggaard;

    2009-01-01

    Thick photoresist coating for electrode patterning in an anisotropically etched V-groove is investigated for electrically controlled liquid crystal photonic bandgap fibre devices. The photoresist step coverage at the convex corners is compared with and without soft baking after photoresist spin...... coating. Two-step UV exposure is applied to achieve a complete exposure for the thick photoresist layer at the bottom of the V-groove, and minimise the reduction in resolution and image distortion. The resolution reduction of the different open window width for electrode pattern transfer is also...

  18. X-ray spontaneous emission control by 1-dimensional photonic bandgap structure

    OpenAIRE

    André, Jean-Michel; Jonnard, Philippe

    2010-01-01

    Paper available at http://epjd.edpsciences.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/epjd/abs/2010/06/d09549/d09549.html International audience The possibility of controlling the X-ray spontaneous emission of atoms embedded in a 1-dimensional photonic bandgap structure by the so-called Purcell effect, is studied. Calculations of the spontaneously emitted power are presented from Fermi's golden rule in the framework of the Wigner-time approach extended to ...

  19. Compression of realistic laser pulses in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, John

    2009-01-01

    Dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap fiber is studied numerically. The performance of ideal parabolic input pulses is compared to pulses from a narrowband picosecond oscillator broadened by self-phase modulation during...... amplification. It is shown that the parabolic pulses are superior for compression of high-quality femtosecond pulses up to the few-megawatts level. With peak powers of 5-10 MW or higher, there is no significant difference in power scaling and pulse quality between the two pulse types for comparable values...

  20. Robust topology optimization of three-dimensional photonic-crystal band-gap structures

    CERN Document Server

    Men, Han; Freund, Robert M; Peraire, Jaime; Johnson, Steven G

    2014-01-01

    We perform full 3D topology optimization (in which "every voxel" of the unit cell is a degree of freedom) of photonic-crystal structures in order to find optimal omnidirectional band gaps for various symmetry groups, including fcc (including diamond), bcc, and simple-cubic lattices. Even without imposing the constraints of any fabrication process, the resulting optimal gaps are only slightly larger than previous hand designs, suggesting that current photonic crystals are nearly optimal in this respect. However, optimization can discover new structures, e.g. a new fcc structure with the same symmetry but slightly larger gap than the well known inverse opal, which may offer new degrees of freedom to future fabrication technologies. Furthermore, our band-gap optimization is an illustration of a computational approach to 3D dispersion engineering which is applicable to many other problems in optics, based on a novel semidefinite-program formulation for nonconvex eigenvalue optimization combined with other techniq...

  1. Bandgap characteristics of 2D plasma photonic crystal with oblique incidence: TM case

    Institute of Scientific and Technical Information of China (English)

    Xie Ying-Tao; Yang Li-Xia

    2011-01-01

    A novel periodic boundary condition (PBC), that is the constant transverse wavenumber (CTW) method, is introduced to solve the time delay in the transverse plane with oblique incidence. Based on the novel PBC, the FDTD/PBC algorithm is proposed to study periodic structure consisting of plasma and vacuum. Then the reflection coefficient for the plasma slab from the FDTD/PBC algorithm is compared with the analytic results to show the validity of our technique. Finally, the reflection coefficients for the plasma photonic crystals are calculated using the FDTD/PBC algorithm to study the variation of bandgap characteristics with the incident angle and the plasma parameters. Thus it has provided the guiding sense for the actual manufacturing plasma photonic crystal.

  2. Slow-light effect in a silicon photonic crystal waveguide as a sub-bandgap photodiode.

    Science.gov (United States)

    Terada, Yosuke; Miyasaka, Kenji; Ito, Hiroyuki; Baba, Toshihiko

    2016-01-15

    We demonstrate a Si sub-bandgap photodiode in a photonic crystal slow-light waveguide that operates at telecom wavelengths and can be fabricated using a Ge-free, standard Si-photonics CMOS process. In photodiodes based on absorption via mid-bandgap states, the slow-light enhancement enables performance that is well balanced among high responsivity, low dark current, high speed, wide working spectrum, and CMOS-process compatibility, all of which are otherwise difficult to achieve simultaneously. Owing to the slow-light effect and supplemental gain at a high reverse bias, the photodiode shows a responsivity of 0.15  A/W with a low dark current of 40 nA, which is attributed to no particular processes such as ion implantation and excess exposure of the Si surface. The maximum responsivity was 0.36  A/W. The modest gain allows for sufficient frequency bandwidth to observe an eye opening at up to 30  Gb/s. PMID:26766696

  3. Study on ceramic photonic bandgap structure with three-dimensional diamond lattice

    Institute of Scientific and Technical Information of China (English)

    Haiqing Yin; Wenbin Cao; Y. Miyamoto

    2006-01-01

    A novel process, which was based on powder injection molding, was investigated for the fabrication of ceramic photonic bandgap structure with three-dimensional diamond lattice. The SiO2-TiO2 ceramic powder was mixed with a water-soluble agent to produce slurry. The slurry was then injected into an epoxy mold with inverse diamond lattice, fabricated by the stereolitographic rapid prototyping process. To increase the density of the green compact, cold isostatic pressing was applied on the unit. Using thermal debinding, the water-soluble agent and the epoxy were extracted at 360 and 650 K, respectively. Sintering was immediately done at 950 K for 5 h and the desired three-dimensional ceramic structure was obtained. The calculated band diagram for this structure indicated the existence of an absolute photonic bandgap for all wave vectors. At 14.7-18.5 GHz, a complete band gap was located with a maximum attenuation of 30 dB at 17 GHz, when transmission was measured in the 〈100〉 direction between 10 and 20 GHz.

  4. Continuously tunable devices based on electrical control of dual-frequency liquid crystal filled photonic bandgap fibers

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Riishede, Jesper;

    2005-01-01

    We present an electrically controlled photonic bandgap fiber device obtained by infiltrating the air holes of a photonic crystal fiber (PCF) with a dual-frequency liquid crystal (LC) with pre-tilted molecules. Compared to previously demonstrated devices of this kind, the main new feature of this...... one is its continuous tunability due to the fact that the used LC does not exhibit reverse tilt domain defects and threshold effects. Furthermore, the dual-frequency features of the LC enables electrical control of the spectral position of the bandgaps towards both shorter and longer wavelengths in...

  5. Simulation Design for Rutile-TiO2 Nanostructures with a Large Complete-Photonic Bandgap in Electrolytes

    Directory of Open Access Journals (Sweden)

    Toshihiro Isobe

    2012-10-01

    Full Text Available The photonic bands of various TiO2 2D photonic crystals, i.e., cylindrical, square and hexagonal columns connected with/without walls and filled with acetonitrile, were investigated from the perspective of dye-sensitized solar cells. The finite-difference time-domain methods revealed that two-dimensional (2D photonic crystals with rods connected with walls composed of TiO2 and electrolytes had complete photonic band gaps under specific conditions. This optimally designed bandgap reaches a large Δω/ωmid value, 1.9%, in a triangular array of square rods connected with walls, which is the largest complete 2D bandgap thus far reported for a photochemical system. These discoveries would promote the photochemical applications of photonic crystals.

  6. Using microwave and macroscopic samples of dielectric solids to study the photonic properties of disordered photonic bandgap materials.

    Science.gov (United States)

    Hashemizad, Seyed Reza; Tsitrin, Sam; Yadak, Polin; He, Yingquan; Cuneo, Daniel; Williamson, Eric Paul; Liner, Devin; Man, Weining

    2014-09-26

    Recently, disordered photonic materials have been suggested as an alternative to periodic crystals for the formation of a complete photonic bandgap (PBG). In this article we will describe the methods for constructing and characterizing macroscopic disordered photonic structures using microwaves. The microwave regime offers the most convenient experimental sample size to build and test PBG media. Easily manipulated dielectric lattice components extend flexibility in building various 2D structures on top of pre-printed plastic templates. Once built, the structures could be quickly modified with point and line defects to make freeform waveguides and filters. Testing is done using a widely available Vector Network Analyzer and pairs of microwave horn antennas. Due to the scale invariance property of electromagnetic fields, the results we obtained in the microwave region can be directly applied to infrared and optical regions. Our approach is simple but delivers exciting new insight into the nature of light and disordered matter interaction. Our representative results include the first experimental demonstration of the existence of a complete and isotropic PBG in a two-dimensional (2D) hyperuniform disordered dielectric structure. Additionally we demonstrate experimentally the ability of this novel photonic structure to guide electromagnetic waves (EM) through freeform waveguides of arbitrary shape.

  7. SU-8 process optimization for high fiber coupling efficiency of liquid crystal filled photonic bandgap fiber components

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    SU-8 structures are built up to increase the fiber coupling efficiency of liquid crystal photonic bandgap fiber components. The resolution reduction of UV exposure is minimized to 4%, and insertion loss is reduced to 2.7dB....

  8. Backward Secondary-Wave Coherence Errors in Photonic Bandgap Fiber Optic Gyroscopes

    Science.gov (United States)

    Xu, Xiaobin; Song, Ningfang; Zhang, Zuchen; Jin, Jing

    2016-01-01

    Photonic bandgap fiber optic gyroscope (PBFOG) is a novel fiber optic gyroscope (FOG) with excellent environment adaptability performance compared to a conventional FOG. In this work we find and investigate the backward secondary-wave coherence (BSC) error, which is a bias error unique to the PBFOG and caused by the interference between back-reflection-induced and backscatter-induced secondary waves. Our theoretical and experimental results show a maximum BSC error of ~4.7°/h for a 300-m PBF coil with a diameter of 10 cm. The BSC error is an important error source contributing to bias instability in the PBFOG and has to be addressed before practical applications of the PBFOG can be implemented. PMID:27338388

  9. Backward Secondary-Wave Coherence Errors in Photonic Bandgap Fiber Optic Gyroscopes.

    Science.gov (United States)

    Xu, Xiaobin; Song, Ningfang; Zhang, Zuchen; Jin, Jing

    2016-01-01

    Photonic bandgap fiber optic gyroscope (PBFOG) is a novel fiber optic gyroscope (FOG) with excellent environment adaptability performance compared to a conventional FOG. In this work we find and investigate the backward secondary-wave coherence (BSC) error, which is a bias error unique to the PBFOG and caused by the interference between back-reflection-induced and backscatter-induced secondary waves. Our theoretical and experimental results show a maximum BSC error of ~4.7°/h for a 300-m PBF coil with a diameter of 10 cm. The BSC error is an important error source contributing to bias instability in the PBFOG and has to be addressed before practical applications of the PBFOG can be implemented.

  10. Applied electric field to fabricate colloidal crystals with the photonic band-gap in communication waveband

    Institute of Scientific and Technical Information of China (English)

    Yan Hai-Tao; Wang Ming; Ge Yi-Xian; Yu Ping

    2009-01-01

    The macropore silica colloidal crystal templates were assembled orderly in a capillary glass tube by an applied electric field method to control silica deposition. In order to achieve the photonic band gap (PBG) of colloidal crystal in optical communication waveband, the diameter of silica microspheres is selected by Bragg diffraction formula. An experiment was designed to test the bandgap of the silica crystal templates. This paper discusses the formation process and the close-packed fashion of the silica colloidal crystal templates was discussed. The surface morphology of the templates was also analyzed. The results showed that the close-packed fashion of silica array templates was face-centered cubic (FCC) structure. The agreement is very good between the experimental data and the theoretical calculation.

  11. Hyperuniform disordered photonic bandgap materials, from microwave to infrared wavelength regime

    Science.gov (United States)

    Man, Weining

    Recently, we have introduced a new class of hyperuniform disordered (HUD) photonic bandgap (PBG) materials enabled by a novel constrained optimization method for engineering the material's Fourier transform to be continuous, isotropic and stealthy. Their structure factor S (k) is equal to zero for small kand exhibits a broad ring of maximum values around a characteristic wave-length range. Experimentally, an isotropic complete PBG (at all angles and for all polarizations) in an alumina-based HUD structure and single-polarized PBGs for plastic-based HUD structure have been demonstrated. Using measured and simulated transmission and phase delay information through these HUD structures, we also unfolded their band structures and reconstructed the effective dispersion relations of propagating electromagnetic modes in them. The intrinsic isotropy in these disordered structures is an inherent advantage associated with the lack of crystalline order, offering unprecedented freedom for functional defect design impossible to achieve in photonic crystals. In the microwave regime, we have shown the creation of freeform waveguides, which can channel photons robustly along arbitrarily curved paths and around sharp bends, and be decorated with defects to produce sharply resonant structures useful for filtering and frequency splitting. Recent simulation and experimental results for waveguides and modulators based on submicron-scale planar hyperuniform disordered PBG structures further highlight their ability to serve as highly compact, flexible and energy-efficient platforms for photonic integrated circuits. NSF DMR-1308084, EPSRC (UK) DTG Grant KD5050, EPSRC (UK) Strategic Equipment Grant EP/M008576/1, NSF SBIR-1345168, NSF MRI-1040444.

  12. Monolithic Yb-fiber femtosecond laser with intracavity all-solid PBG fiber and ex-cavity HC-PCF

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2010-01-01

    (PM) photonic bandgap fiber (PBG) is used in the cavity of the master oscillator for dispersion compensation and stabilization of modelocking. The final compression of an chirped-pulse-amplified laser signal is performed in a hollow PM PCF, yielding final fiber-delivered pulse energy of around 7 n......We demonstrate an all-fiber femtosecond master oscillator / power amplifier operating at the central wavelength of 1033 nm, based on Yb-doped fiber as gain medium, and two different kinds of photonic crystal fibers for dispersion control and stabilization. An all-solid (AS) polarization maintaining...

  13. Investigation of the guided-mode characteristics of hollow-core photonic band-gap fibre with interstitial holes

    Institute of Scientific and Technical Information of China (English)

    Yuan Jin-Hui; Yu Chong-Xiu; Sang Xin-Zhu; Zhang Jin-Long; Zhou Gui-Yao; Li Shu-Guang; Hou Lan-Tian

    2011-01-01

    This paper investigates the guided-mode characteristics of hollow-core photonic band-gap fibre (HC-PBGF) with interstitial holes fabricated by an improved twice stack-and-draw technique at visible wavelengths. Based on the simulation model with interstitial holes, the influence of glass interstitial apexes on photonic band-gaps is discussed.The existing forms of guided-mode in part band gaps are shown by using the full-vector plane-wave method. In the experiment, the observed transmission spectrum corresponds to the part band gaps obtained by simulation. The fundamental and second-order guided-modes with mixture of yellow and green light are observed through choosing appropriate fibre length and adjusting coupling device. The loss mechanism of guided-modes in HC-PBGF is also discussed.

  14. Compact Design of an Electrically Tunable and Rotatable Polarizer Based on a Liquid Crystal Photonic Bandgap Fiber

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    In this letter, a compact electrically controlled broadband liquid crystal (LC) photonic bandgap fiber polarizer is designed and fabricated. A good fiber coupling quality between two single-mode fibers and one 10-mm-long LC-filled photonic crystal fiber is obtained and protected by using SU-8 fiber...... fixing structures during the device assembly. The total insertion loss of this all-in-fiber device is 2.7 dB. An electrically tunable polarization extinction ratio of 21.3 dB is achieved with 45$^{circ}$ rotatable transmission axis as well as switched on and off in the wavelength range of 1300–1600 nm....

  15. X-Band Photonic Band-Gap Accelerator Structure Breakdown Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, Roark A.; /MIT /MIT /NIFS, Gifu /JAERI, Kyoto /LLNL, Livermore; Shapiro, Michael A.; Temkin, Richard J.; /MIT; Dolgashev, Valery A.; Laurent, Lisa L.; Lewandowski, James R.; Yeremian, A.Dian; Tantawi, Sami G.; /SLAC

    2012-06-11

    In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at X band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of 65 MV/m yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above 110 MV/m was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of 100 MV/m and a surface magnetic field of 890 kA/m. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric field effects. These PBG structure results highlight the unexpected role of magnetic fields in breakdown. The hypothesis is presented that the moderate level electric field on the inner rods, about 14 MV/m, is enhanced at small tips and projections caused by pulsed heating, leading to breakdown. Future PBG structures should be built to minimize pulsed surface heating and temperature rise.

  16. Bandgap Engineering of Double Perovskites for One- and Two-photon Water Splitting

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel

    2013-01-01

    Computational screening is becoming increasingly useful in the search for new materials. We are interested in the design of new semiconductors to be used for light harvesting in a photoelectrochemical cell. In the present paper, we study the double perovskite structures obtained by combining 46...... stable cubic perovskites which was found to have a finite bandgap in a previous screening-study. The four-metal double perovskite space is too large to be investigated completely. For this reason we propose a method for combining different metals to obtain a desired bandgap. We derive some bandgap design...

  17. Approximate equivalence between guided modes in a low-contrast photonic bandgap fiber and Maxwell TM modes of a high-contrast two-dimensional photonic structure

    CERN Document Server

    Legrand, Olivier; Vanneste, Christian

    2010-01-01

    We present a formal analogy between the eigenvalue problem for guided scalar modes in a low-contrast photonic bandgap fiber and quasi-stationary TM modes of a two-dimensional (2D) photonic structure. Using this analogy, we numerically study the confinement losses of disordered microstructured fibers through the leakage rate of an open 2D system with high refractive index inclusions. Our results show that for large values of the disorder, the confinement losses increase. However, they also suggest that losses might be improved in strongly disordered fibers by exploring ranges of physical parameters where Anderson localization sets in.

  18. A two-dimensional photonic crystal with six large bandgaps formed by a hexagonal lattice of anisotropic cylinders

    Institute of Scientific and Technical Information of China (English)

    庄飞; 吴良; 何赛灵

    2002-01-01

    The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystalformed by a hexagonal structure of anisotropic cylinders. Two cylindrical inclusions in the unit cell have two differentradii, R1 and R2 (Ri<R2). By reducing the symmetry of the structure and choosing appropriately parameters R2and s = R1/R2 (s<1), we obtain six large complete bandgaps, among which three are over 0.05 ωe (where ωe = 2πc/a)in the high region of the normalized frequency (however, one of these over 0.065 ωe is not stable). There are two otherstable complete bandgaps in the low-frequency region.

  19. A two—dimensional photonic crystal with six large bandgaps formed by a hexagonal lattice of anisotropic cylinders

    Institute of Scientific and Technical Information of China (English)

    庄飞; 吴良; 等

    2002-01-01

    The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystal formed by a hexagonal structure of anisotropic cylinders.Two cylindrical inclusions in the unit cell have two different radii,R1 and R2(R1bandgaps,among which three are over 0.05 we(where we=2πc/α)in the high region of the normalized frequency (however,one of these over 0.065 we is not stable).There are two other stable complete bandgaps in the low-frequency region.

  20. Monolithic femtosecond Yb-fiber laser with photonic crystal fibers

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    We demonstrate a monolithic stable SESAM-modelocked self-starting Yb-fiber laser. A novel PM all-solid photonic bandgap fiber is used for intra-cavity of dispersion management. The ex-cavity final pulse compression is performed in a spliced-on PM hollow-core photonic crystal fiber. The laser...

  1. 1178 nm all Yb-fiber laser source power-scaled by solid-core photonic bandgap fiber for 589nm generation

    DEFF Research Database (Denmark)

    Maruyama, H.; Shirakawa, A.; Ueda, K.I.;

    2009-01-01

    Here we report an 1178 nm all Yb-fiber laser source power-scaled by solid-core photonic bandgap fiber (SC-PBGF) for 589 nm generation. A 1.4 W output at 589 nm with an input power of 9 W at 1178 nm were obtained. One important advantage of PBGF is distributed filtering. Hence the gain spectrum can...

  2. Simultaneous coupling of surface plasmon resonance and photonic bandgap to InGaAs quantum well emission

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongwei [Engineering Product Development, Singapore University of Technology and Design, Singapore 487372 (Singapore); Teng, Jinghua [Institute of Materials Research and Engineering, Singapore 117602 (Singapore); Chua, Soo Jin, E-mail: elecsj@nus.edu.sg [Institute of Materials Research and Engineering, Singapore 117602 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2016-01-07

    A photonic bandgap structure was created on the 100 nm thick GaAs barrier layer with Au nanodisks deposited inside the holes. To mitigate the nonradiative surface recombination of GaAs, the Au nanodisks were formed on top of a 15 nm SiO{sub 2} deposited in the holes. A maximum 7.6-fold increase in photoluminescence intensity was obtained at the etch depth of 80 nm. In this configuration, the Au nanodisk is separated from the quantum well by 20 nm of GaAs and 15 nm of SiO{sub 2}. The experimental result was verified by the simulation based on this structure. There was a good agreement between experiments with simulation results.

  3. Measurement and suppression of secondary waves caused by high-order modes in a photonic bandgap fiber-optic gyroscope.

    Science.gov (United States)

    Xu, Xiaobin; Gao, Fuyu; Song, Ningfang; Jin, Jing

    2016-05-16

    Air-core photonic bandgap fiber (PBF) is a good choice for fiber-optic gyroscopes (FOGs) owing to the fact that it can be adapted to a wide variety of environments. However, its multimode properties are disadvantageous for the application to FOGs. An interference-based method is proposed to precisely determine the secondary waves caused by the high-order modes and their coupling. Based on the method, two groups of secondary waves have been found, having optical path differences (OPDs) of ~1.859 m and ~0.85 m, respectively, relative to the primary waves in a PBFOG that consists of a 7-cell PBF coil, approximately 180 m in length. Multi-turn bends of the PBF at both ends of the PBF coil after the fusion splicing points are shown to suppress the intensity of these secondary waves by approximately 10 dB. PMID:27409849

  4. Wide bandgap semiconductors. Fundamental properties and modern photonic and electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K. [Nippon EMC Ltd. (Japan). R and D Center; Yoshikawa, A. [Chiba Univ. (Japan); Sandhu, A. (eds.) [Tokyo Institute of Technology (Japan)

    2007-07-01

    This book offers a comprehensive overview of the development, current state and future prospects of wide bandgap semiconductor materials and related optoelectronics devices. It includes an overview of recent developments in III-V nitride semiconductors, SiC, diamond, ZnO, II-VI materials and related devices including AIGaN/GaN FET, UV LDs, white light LEDs, and cold electron emitters. With 901 references, 333 figures and 21 tables, this book will serve as a one-stop source of knowledge on wide bandgap semiconductors and related optoelectronics devices. After review of the basic physics of WBGS and the relevance of the physical properties to the development of commercial devices, the book addresses the applications of WBGS devices for solid-state white-light illumination, medicine and gigahertz-high power telecommunications. In addition, description of recent development in the growth and applications of nitride semiconductors are complemented by chapters on the properties and device applications of SiC, diamond thin films, doping of ZnO, II-IVs and the novel BeZnSeTe/BAlGaAs material systems. Practical issues and problems such as the effect of defects on device performance are highlighted and solutions proposed based on recent studies. (orig.)

  5. Existing conditions of full bandgaps and absolute negative refraction in metallic-dielectric photonic crystal

    Institute of Scientific and Technical Information of China (English)

    Dong Jian-Wen; Hu Xin-Hua; Wang He-Zhou

    2007-01-01

    This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallicdielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10% is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.

  6. Compact nanocavity with elliptical slot inside photonic wire bandgap materials including sidewalls gratings for biosensing

    Science.gov (United States)

    Daraei, Ahmadreza; Daraei, Mohammad Esmaeil

    2016-07-01

    In this paper, we introduce and propose a compact and multipurpose one-dimensional photonic crystal silicon wire nanocavity (NC) sensor in silicon-on-insulator wafers. A slot with elliptical cross section (SECS) in the center of the NC together with tapered sidewalls grating of photonic wire (PhWr) provides strongly confined photonic modes for the sensing purposes. We have examined and optimized several geometrical parameters of the PhWr and SECS NC theoretically and computationally. Using finite element method, we have operated our computational validation for the variety of designs. Our results have shown strongly confined photonic mode with high quality ( Q) factor ~1.6 × 104, small modal volume, V mod ~ 0.005( λ/ n)3, as well as high sensitivity as 530 nm/RIU simultaneously operating nearly at the telecom window. These results are promising for refractive index-based sensing, e.g., nanobiomaterials.

  7. Electrically tunable long-period gratings in liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Scolari, Lara; Lægsgaard, Jesper;

    2007-01-01

    We demonstrate an aLl-electrically tunable long period grating in a photonic crystal fiber infiltrated with a nematic liquid crystal. The spectral dips and the resonance wavelengths are tuned electrically and thermally, respectively.......We demonstrate an aLl-electrically tunable long period grating in a photonic crystal fiber infiltrated with a nematic liquid crystal. The spectral dips and the resonance wavelengths are tuned electrically and thermally, respectively....

  8. Design of Photonic Bandgap Fibre with Novel Air-Hole Structure

    Institute of Scientific and Technical Information of China (English)

    LI Jing; ZHANG Wei-Gang; DU Jiang-Bing; WANG Zhi; LIU Yan-Ge; DONG Xiao-Yi

    2008-01-01

    We introduce PBGFs with the cladding made of our newly designed quasi-hexagonal air holes and demonstrate how it actually operates. This cladding structure is introduced for the first time to the best of our knowledge, and is realized by making use of the hydrofluoric acid's corrosive properties. The fibre corrosion can be accurately controlled, thus opening us the gate for the design and fabrication of new PBGFs with more complex and more efficient cladding structures. Numerical results and actual simulations indicate that PBGFs built with this cladding structure have improved bandgap properties and guiding bands as wide as 500nm have been theoretically reached. Using the same method, we have also been able to design two other types of PBGFs with improved cladding structure.

  9. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    Science.gov (United States)

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-07-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately ‑0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically).

  10. Nonlinear optical sub-bandgap excitation of ZnO-based photonic resonators

    Science.gov (United States)

    Bader, Christina A.; Zeuner, Franziska; Bader, Manuel H. W.; Zentgraf, Thomas; Meier, Cedrik

    2015-12-01

    Zinc oxide (ZnO) is a versatile candidate for photonic devices due to its highly efficient optical emission. However, for pumping of ZnO photonic devices UV-sources are required. Here, we investigate the alternative usage of widely available pulsed near-infrared (NIR)-sources and compare the efficiency of linear and nonlinear excitation processes. We found that bulk ZnO, ZnO thin films grown by molecular beam epitaxy, and ZnO/SiO2 microdisk devices exhibit strong nonlinear response when excited with NIR pulses (λ ≈ 1060 nm). In addition, we show that the ZnO/SiO2 microdisks exhibit sharp whispering gallery modes over the blue-yellow part of the visible spectrum for both excitation conditions and high Q-factors up to Q = 4700. The results demonstrate that nonlinear excitation is an efficient way to pump ZnO photonic devices.

  11. Two-Dimensional Photonic Band-Gap Defect Modes with Deformed Lattice

    Institute of Scientific and Technical Information of China (English)

    CAI Xiang-Hua; ZHENG Wan-Hua; MA Xiao-Tao; REN Gang; XIA Jian-Bai

    2005-01-01

    @@ A numerical study of the defect modes in two-dimensional photonic crystals with deformed triangular lattice is presented by using the supercell method and the finite-difference time-domain method We find the stretch or shrink of the lattice can bring the change not only on the frequencies of the defect modes but also on their magnetic field distributions. We obtain the separation of the doubly degenerate dipole modes with the change of the lattice and find that both the stretch and the shrink of the lattice can make the dipole modes separate large enough to realize the single-mode emission. These results may be advantageous to the manufacture of photonic crystal lasers and provide a new way to realize the single-mode operation in photonic crystal lasers.

  12. Nonlinear optical sub-bandgap excitation of ZnO-based photonic resonators

    International Nuclear Information System (INIS)

    Zinc oxide (ZnO) is a versatile candidate for photonic devices due to its highly efficient optical emission. However, for pumping of ZnO photonic devices UV-sources are required. Here, we investigate the alternative usage of widely available pulsed near-infrared (NIR)-sources and compare the efficiency of linear and nonlinear excitation processes. We found that bulk ZnO, ZnO thin films grown by molecular beam epitaxy, and ZnO/SiO2 microdisk devices exhibit strong nonlinear response when excited with NIR pulses (λ ≈ 1060 nm). In addition, we show that the ZnO/SiO2 microdisks exhibit sharp whispering gallery modes over the blue-yellow part of the visible spectrum for both excitation conditions and high Q-factors up to Q = 4700. The results demonstrate that nonlinear excitation is an efficient way to pump ZnO photonic devices

  13. Coherence effects in propagation through one-dimensional photonic bandgap structures with a rough glass interface

    NARCIS (Netherlands)

    Mandatori, Antonio; Bertolotti, Mario; Sibilia, Concita; Hoenders, Bert J.; Scalora, Michael

    2007-01-01

    The effect of the coherence of a beam traveling through a photonic ID structure coupled with a rough glass is studied. The analysis is made for the case of spatial coherence showing the possibility to determine the coherence characteristics of the beam by an examination of the output field. We have

  14. 光子带隙结构在微带带通滤波器中的应用%Application of Photonic Bandgap Structure in Microstrip Bandpass Filters

    Institute of Scientific and Technical Information of China (English)

    高强; 闫敦豹; 袁乃昌; 付云起

    2004-01-01

    介绍了两种带有一维光子带隙(Photonic Bandgap,简称PBG)结构的微带带通滤波器.它们具有良好的慢波、带阻特性,同时在结构上又无须腐蚀接地板,而仅仅修改微带线的形状.计算仿真与测量结果基本相符合.

  15. Investigation on the Effect of Underwater Acoustic Pressure on the Fundamental Mode of Hollow-Core Photonic Bandgap Fibers

    Directory of Open Access Journals (Sweden)

    Adel Abdallah

    2015-01-01

    Full Text Available Recently, microstructured optical fibers have become the subject of extensive research as they can be employed in many civilian and military applications. One of the recent areas of research is to enhance the normalized responsivity (NR to acoustic pressure of the optical fiber hydrophones by replacing the conventional single mode fibers (SMFs with hollow-core photonic bandgap fibers (HC-PBFs. However, this needs further investigation. In order to fully understand the feasibility of using HC-PBFs as acoustic pressure sensors and in underwater communication systems, it is important to study their modal properties in this environment. In this paper, the finite element solver (FES COMSOL Multiphysics is used to study the effect of underwater acoustic pressure on the effective refractive index neff of the fundamental mode and discuss its contribution to NR. Besides, we investigate, for the first time to our knowledge, the effect of underwater acoustic pressure on the effective area Aeff and the numerical aperture (NA of the HC-PBF.

  16. Polarization Properties of Elliptical-Hole Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Tartarini, Giovanni; Pansera, Marco; Alkeskjold, Thomas Tanggaard;

    2007-01-01

    ellipticity allow some phenomena that are not predicted yet, such as polarization-dependent losses and birefringence sign change in the wavelength range used for standard telecom fibers. Control of these features allows the design of new devices for sensing or telecommunication applications......The characteristics of triangular photonic crystal fibers (PCFs) with elliptical holes filled with a nematic liquid crystal (LC) are investigated theoretically. The analysis that is carried out using the finite-element method, including material dispersion effects, shows that LC anisotropy and hole...

  17. Room temperature all-silicon photonic crystal nanocavity light emitting diode at sub-bandgap wavelengths

    CERN Document Server

    Shakoor, A; Cardile, P; Portalupi, S L; Gerace, D; Welna, K; Boninelli, S; Franzo, G; Priolo, F; Krauss, T F; Galli, M; Faolain, L O

    2013-01-01

    Silicon is now firmly established as a high performance photonic material. Its only weakness is the lack of a native electrically driven light emitter that operates CW at room temperature, exhibits a narrow linewidth in the technologically important 1300- 1600 nm wavelength window, is small and operates with low power consumption. Here, an electrically pumped all-silicon nano light source around 1300-1600 nm range is demonstrated at room temperature. Using hydrogen plasma treatment, nano-scale optically active defects are introduced into silicon, which then feed the photonic crystal nanocavity to enahnce the electrically driven emission in a device via Purcell effect. A narrow ({\\Delta}{\\lambda} = 0.5 nm) emission line at 1515 nm wavelength with a power density of 0.4 mW/cm2 is observed, which represents the highest spectral power density ever reported from any silicon emitter. A number of possible improvements are also discussed, that make this scheme a very promising light source for optical interconnects a...

  18. Photonic band-gap engineering for volume plasmon polaritons in multiscale multilayer hyperbolic metamaterials

    CERN Document Server

    Zhukovsky, Sergei V; Babicheva, Viktoriia E; Lavrinenko, Andrei V; Sipe, J E

    2013-01-01

    We theoretically study the propagation of large-wavevector waves (volume plasmon polaritons) in multilayer hyperbolic metamaterials with two levels of structuring. We show that when the parameters of a subwavelength metal-dielectric multilayer ("substructure") are modulated ("superstructured") on a larger, wavelength scale, the propagation of volume plasmon polaritons in the resulting multiscale hyperbolic metamaterials is subject to photonic band gap phenomena. A great degree of control over such plasmons can be exerted by varying the superstructure geometry. When this geometry is periodic, stop bands due to Bragg reflection are shown to form within the volume plasmonic band. When a cavity layer is introduced in an otherwise periodic superstructure, resonance peaks of the Fabry-P\\'erot nature are shown to be present within the stop bands. More complicated superstructure geometries are also considered. For example, fractal Cantor-like multiscale metamaterials are found to exhibit characteristic self-similar s...

  19. Continuously tunable all-in-fiber devices based on thermal and electrical control of negative dielectric anisotropy liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Eskildsen, Lars; Weirich, Johannes;

    2009-01-01

    and corresponding activation loss are measured by using polarized light and a full broadband polarization control setup. The electrically induced phase shift on the Poincaré sphere and corresponding birefringence change are also measured. According to the results, tunable wave plates working in the wavelength range......We infiltrate photonic crystal fibers with a negative dielectric anisotropy liquid crystal. 396nm bandgap shift is obtained in the temperature range 22°C-80°C, and 67 nm shift of long-wavelength bandgap edge is achieved by applying a voltage of 200Vrms. The polarization sensitivity...... 1520nm-1580nm and a potential for realizing a polarimeter working at 1310nm region are experimentally demonstrated....

  20. A Multifrequency Notch Filter for Millimeter Wave Plasma Diagnostics based on Photonic Bandgaps in Corrugated Circular Waveguides

    Directory of Open Access Journals (Sweden)

    Wagner D.

    2015-01-01

    Full Text Available Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Heating applied in nuclear fusion plasmas. A notch filter based on a waveguide Bragg reflector (photonic band-gap may provide several stop bands of defined width within up to two standard waveguide frequency bands. A Bragg reflector that reflects an incident fundamental TE11 into a TM1n mode close to cutoff is combined with two waveguide tapers to fundamental waveguide diameter. Here the fundamental TE11 mode is the only propagating mode at both ends of the reflector. The incident TE11 mode couples through the taper and is converted to the high order TM1n mode by the Bragg structure at the specific Bragg resonances. The TM1n mode is trapped in the oversized waveguide section by the tapers. Once reflected at the input taper it will be converted back into the TE11 mode which then can pass through the taper. Therefore at higher order Bragg resonances, the filter acts as a reflector for the incoming TE11 mode. Outside of the Bragg resonances the TE11 mode can propagate through the oversized waveguide structure with only very small Ohmic attenuation compared to propagating in a fundamental waveguide. Coupling to other modes is negligible in the non-resonant case due to the small corrugation amplitude (typically 0.05·λ0, where λ0 is the free space wavelength. A Bragg reflector for 105 and 140 GHz was optimized by mode matching (scattering matrix simulations and manufactured by SWISSto12 SA, where the required mechanical accuracy of ± 5 μm could be achieved by stacking stainless steel rings, manufactured by micro-machining, in a high precision guiding pipe. The two smooth-wall tapers were fabricated by electroforming. Several measurements were performed using vector network analyzers from Agilent (E8362B, ABmm (MVNA 8-350 and Rohde&Schwarz (ZVA24 together with frequency multipliers. The

  1. A Multifrequency Notch Filter for Millimeter Wave Plasma Diagnostics based on Photonic Bandgaps in Corrugated Circular Waveguides

    Science.gov (United States)

    Wagner, D.; Bongers, W.; Kasparek, W.; Leuterer, F.; Monaco, F.; Münich, M.; Schütz, H.; Stober, J.; Thumm, M.; Brand, H. v. d.

    2015-03-01

    Sensitive millimeter wave diagnostics need often to be protected against unwanted radiation like, for example, stray radiation from high power Electron Cyclotron Heating applied in nuclear fusion plasmas. A notch filter based on a waveguide Bragg reflector (photonic band-gap) may provide several stop bands of defined width within up to two standard waveguide frequency bands. A Bragg reflector that reflects an incident fundamental TE11 into a TM1n mode close to cutoff is combined with two waveguide tapers to fundamental waveguide diameter. Here the fundamental TE11 mode is the only propagating mode at both ends of the reflector. The incident TE11 mode couples through the taper and is converted to the high order TM1n mode by the Bragg structure at the specific Bragg resonances. The TM1n mode is trapped in the oversized waveguide section by the tapers. Once reflected at the input taper it will be converted back into the TE11 mode which then can pass through the taper. Therefore at higher order Bragg resonances, the filter acts as a reflector for the incoming TE11 mode. Outside of the Bragg resonances the TE11 mode can propagate through the oversized waveguide structure with only very small Ohmic attenuation compared to propagating in a fundamental waveguide. Coupling to other modes is negligible in the non-resonant case due to the small corrugation amplitude (typically 0.05·λ0, where λ0 is the free space wavelength). A Bragg reflector for 105 and 140 GHz was optimized by mode matching (scattering matrix) simulations and manufactured by SWISSto12 SA, where the required mechanical accuracy of ± 5 μm could be achieved by stacking stainless steel rings, manufactured by micro-machining, in a high precision guiding pipe. The two smooth-wall tapers were fabricated by electroforming. Several measurements were performed using vector network analyzers from Agilent (E8362B), ABmm (MVNA 8-350) and Rohde&Schwarz (ZVA24) together with frequency multipliers. The stop bands

  2. A Wearable All-Solid Photovoltaic Textile.

    Science.gov (United States)

    Zhang, Nannan; Chen, Jun; Huang, Yi; Guo, Wanwan; Yang, Jin; Du, Jun; Fan, Xing; Tao, Changyuan

    2016-01-13

    A solution is developed to power portable electronics in a wearable manner by fabricating an all-solid photovoltaic textile. In a similar way to plants absorbing solar energy for photosynthesis, humans can wear the as-fabricated photovoltaic textile to harness solar energy for powering small electronic devices.

  3. Photonic Bandgap in Two-dimensional Photonic Crystals of Germanium Columns%锗圆柱构造的二维光子晶体带隙结构分析

    Institute of Scientific and Technical Information of China (English)

    郭普庆; 梁建; 杨毅彪; 许并社

    2011-01-01

    Plane wave expansion method was adopted to calculate the bandgap of 2-D photonic crystals with triangular lattice, kagome lattice and graphite lattice. The structural parameters of photonic crystals with the largest complete bandgap were obtained by optimization calculation.Complete bandgap for graphite lattice appeaed when filling ratio changed in a wide range, and the maximum width of complete bandgap was △=0.053 in the low-energy region.%采用平面波展开法研究了由锗圆柱构成的Triangular格子、Kagome格子和Graphite 格子二维光子晶体的带隙结构,发现Kagome格子和Graphite格子结构的光子晶体具有完全光子带隙,并得到了使完全带隙最大化的结构参数.数值计算结果表明,Graphite结构二维光子晶体在填充比从f=0.058到f=0.605连续变化的很大范围内都有完全带隙出现,在低能区出现了△=0.053(ωa/2πc)的较大带隙.为二维光子晶体材料的制备和应用提供理论依据.为二维光子晶体材料的制备和应用提供理论依据.

  4. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Liefeng, E-mail: fengliefeng@tju.edu.cn, E-mail: lihongru@nankai.edu.cn; Yang, Xiufang; Wang, Cunda; Yao, Dongsheng [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Li, Yang [Business and Vocational College of Hainan, Haikou 570203 (China); Li, Ding; Hu, Xiaodong [Research Center for Wide Band Gap Semiconductors, State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Li, Hongru, E-mail: fengliefeng@tju.edu.cn, E-mail: lihongru@nankai.edu.cn [State Key Laboratory for Medicinal Chemistry and Biology, College of Pharmacy, Nankai University, Tianjin 300071 (China)

    2015-04-15

    The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by I{sub th}{sup l} and I{sub th}{sup u}, as shown in Fig. 2; I{sub th}{sup l} is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; I{sub th}{sup u} is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (V{sub j}) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at I{sub th}{sup l} and I{sub th}{sup u}. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  5. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

    Directory of Open Access Journals (Sweden)

    Liefeng Feng

    2015-04-01

    Full Text Available The junction behavior of different narrow band-gap multi-quantum-well (MQW laser diodes (LDs confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by Ithl and Ithu, as shown in Fig. 2; Ithl is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; Ithu is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (Vj is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at Ithl and Ithu. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  6. Facile construction of dual bandgap optical encoding materials with PS@P(HEMA-co-AA)/SiO2-TMPTA colloidal photonic crystals

    Science.gov (United States)

    Tian, Yu; Zhang, Jing; Liu, Si-Si; Yang, Shengyang; Yin, Su-Na; Wang, Cai-Feng; Chen, Li; Chen, Su

    2016-07-01

    An operable strategy for the construction of dual-reflex optical code materials from bilayer or Janus-structure colloidal photonic crystals (CPCs) has been established in this work. In this process, monodispersed submicrometer polystryene@poly(2-hydroxyethyl methacrylate-co-acrylic acid) hydrogel microspheres with soft-shell/hard-core structure and monodispersed colloidal silica spheres were fabricated. These two kinds of colloidal units can be facilely integrated into a single material without optical signal interference because they are well isolated for the immiscibility between water and ethoxylated trimethylolpropane triacrylate (TMPTA) and the upper layer of SiO2-TMPTA is a kind of transparent. Moreover, diverse optical code series with different dual photonic bandgaps can be obtained via tuning the colloid sizes. Compared to the conventional single-reflex CPCs, the as-prepared dual-reflex optical code materials represented high information capacity in encoding process. More interesting, delicate code pattern has been also achieved on the optical film via the silk-screen printing technique, which will greatly extend the dual-reflex optical code materials to practical uses in areas containing bio-encoding, anti-counterfeiting, and flexible displays.

  7. A hot-electron thermophotonic solar cell demonstrated by thermal up-conversion of sub-bandgap photons

    Science.gov (United States)

    Farrell, Daniel J.; Sodabanlu, Hassanet; Wang, Yunpeng; Sugiyama, Masakazu; Okada, Yoshitaka

    2015-01-01

    The direct conversion of solar energy to electricity can be broadly separated into two main categories: photovoltaics and thermal photovoltaics, where the former utilizes gradients in electrical potential and the latter thermal gradients. Conventional thermal photovoltaics has a high theoretical efficiency limit (84%) but in practice cannot be easily miniaturized and is limited by the engineering challenges of sustaining large (>1,000 K) temperature gradients. Here we show a hot-carrier-based thermophotonic solar cell, which combines the compact nature of photovoltaic devices with the potential to reach the high-efficiency regime of thermal photovoltaics. In the device, a thermal gradient of 500 K is established by hot electrons, under Stokes illumination, rather than by raising the temperature of the material itself. Under anti-Stokes (sub-bandgap) illumination we observe a thermal gradient of ∼20 K, which is maintained by steady-state Auger heating of carriers and corresponds to a internal thermal up-conversion efficiency of 30% between the collector and solar cell. PMID:26541415

  8. Quantum effect and the bandgap of anisotropic rectangle photonic crystal%各向异性矩形光子晶体禁带结构及量子效应

    Institute of Scientific and Technical Information of China (English)

    龙涛; 刘启能

    2011-01-01

    The quantum effect of light wave mode is studied under a condition that the light wave is restricted in 1-D anisotropic rectangle photonic crystal.The bandgap character of TE wave and TM wave are calculated by characteristic matrix method.New bandgap structure of 1-D anisotropic rectangle photonic crystal is obtained.The bandgap frequency and transmission angle increase with increasing quantum number.The bandgap frequency of the same pattern decreases with increasing rectangle side length.%利用光波在一维各向异性矩形光子晶体中横向受限的条件,研究了光波在其中出现的模式量子效应,并利用特征矩阵法计算了TE波和TM波各模式的禁带的变化规律,得出了一些一维各向异性矩形光子晶体禁带的新结构.禁带的频率和透射角都随模式量子数的增加而增大.同一模式禁带的频率随矩形边长的增加而减小.

  9. Low-loss transmission band in photonic crystal waveguides with sharp cutoff at a frequency below the bandgap

    DEFF Research Database (Denmark)

    Krüger, Asger Christian; Zhang, Min; Groothoff, Nathaniel;

    2011-01-01

    We present TE transmission measurements of photonic crystal waveguides with high hole radius to period ratio r/Λ=0.388. This geometry introduces a unique low loss transmission band in addition to the traditional PhC guiding band and very sharp transmission edges for devices with a length of 50 μm...... or longer. Finite difference time domain and plane wave expansion simulations confirm the results and show that the sharpness of the cutoffs can be explained by the spectral shape of the guiding mode in the band diagram....

  10. 太赫兹双芯光子带隙光纤定向耦合器%Terahertz dual-core photonic band-gap fiber directional coupler

    Institute of Scientific and Technical Information of China (English)

    白晋军; 王昌辉; 侯宇; 范飞; 常胜江

    2012-01-01

    提出了一种低损耗、宽频段太赫兹双芯光子带隙光纤定向耦合器,光纤的包层由亚波长尺度呈三角晶格排列的空气孔组成,两个纤芯分别由去掉7个空气孔构成.利用全矢量有限元法对光纤的色散、耦合特性以及损耗特性进行了理论分析.研究表明,这种耦合器的损耗系数小于0.021cm^-1更重要的是可以实现0.14THz范围内的宽频定向耦合.这种定向耦合器在太赫兹通信系统中滤波、波分复用、偏振分离和开关等技术中有潜在的应用价值.%A low-loss and broadband terahertz twin-core photonic band-gap fiber directional coupler is proposed, which consists of a cladding with a triangular lattice array of sub-wavelength air rods and two cores formed respectively by omitting seven nearby air rods. The group veIocity dispersion, the coupling and the loss of the fibers are investigated by using a full-vector finite element method. The numerical simulations show that the loss coefficient of the coupler is less than 0.021 cm^-1, and the coupling broadband of 0.14 THz can be realized. The directional coupler has potential applications in terahertz communication systems, such as filtering, wavelength-division multiplexing, polarization isolation, switching and so on.

  11. Tunable Fabry-Perot filter using hollow-core photonic bandgap fiber and micro-fiber for a narrow-linewidth laser.

    Science.gov (United States)

    Wang, Xiaozhen; Zhu, Tao; Chen, Liang; Bao, Xiaoyi

    2011-05-01

    A novel tunable fiber Fabry-Perot (FP) filter is proposed and demonstrated by using a hollow-core photonic bandgap fiber (HC-PBF) and a micro-fiber. The interference cavity is a hollow core of HC-PBF. One of the reflection mirrors is the splicing point between a section of HC-PBF and a single mode fiber. The other reflection mirror is a gold-coated end of micro-fiber that uses chemical etching process to obtain the similar diameter as the core of HC-PBF. Hence the movable mirror can be adjusted with long distance inside the hollow core of HC-PBF. Tunable FP filter is used as a mode selecting component in the reflection mode to implement stable single longitudinal mode (SLM) operation in a ring laser. With FP cavity length of 0.25 ± 0.14 mm, the wavelength of SLM laser can be tuned over 1554-1562 nm with a tuning step of 0.2-0.3 nm, a side-mode suppression ratio (SMSR) of 32-36 dB and a linewidth of 3.0-5.1 kHz. With FP cavity length of 2.37 ± 0.37 mm, the SLM laser can be tuned over 1557.3-1560.2 nm with a tuning step of 0.06-0.1 nm, a SMSR of 44-51 dB and a linewidth of 1.8-3.0 kHz. PMID:21643220

  12. Novel All Solid-state Polymer Electrolytes for Lithium Battery

    Institute of Scientific and Technical Information of China (English)

    Hui Jiang; Shibi Fang

    2005-01-01

    @@ 1Introduction All solid-state polymer electrolytes for lithium battery was proved to be an attractive direction. Compared with prevenient polymer electrolytes all solid-state polymer electrolytes were superiority in more broad electrochemical window, more stable/low interfacial resistance especially when situ-polymerization utilized, excellent mechanical properties and dissepiment free. A lithium secondary battery using all solid-state polymer electrolyte meet the challenge of energy source for both portable electronic devices and electric vehicles (EV) or engine/battery hybrid vehicles (HEV). All solid-state comb-like network polymer electrolytes (CNPE) based on polysiloxane with internal plasticizing chain (IPC) has been designed and synthesized. See Fig. 1.

  13. A study of potential high band-gap photovoltaic materials for a two step photon intermediate technique in fission energy conversion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Prelas, M.A.

    1996-01-24

    This report describes progress made to develop a high bandgap photovoltaic materials for direct conversion to electricity of excimer radiation produced by fission energy pumped laser. This report summarizes the major achievements in sections. The first section covers n-type diamond. The second section covers forced diffusion. The third section covers radiation effects. The fourth section covers progress in Schottky barrier and heterojunction photovoltaic cells. The fifth section covers cell and reactor development.

  14. 飞秒激光与宽禁带物质相互作用过程中光子-电子-声子之间的微能量传导Ⅰ:光子吸收过程%Microscopic energy transport through photon-electron-phonon interactions during ultrashort laser ablation of wide bandgap materials Part Ⅰ:photon absorption

    Institute of Scientific and Technical Information of China (English)

    姜澜; 李丽珊; 王素梅

    2009-01-01

    The new phenomena induced by femtosecond lasers lead to the new area of ultrafast science.It is a significant challenge to explain the phenomena associated with complex non-equilibrium and non-linear processes.Although there is a growing body of experimental observation,a comprehensive model remains undeveloped.We review the challenges in understanding the photon absorption stage mainly for the femtosecond ablation of wide bandgap materials at the intensities of 1013~1014 W/cm2.Major opinions and challenges in ionization mechanisms are presented by primarily considering multiphoton ionization and avalanche ionization.

  15. All solid state pulsed power system for water discharge

    OpenAIRE

    Sakugawa, Takashi; Yamaguchi, Takahiro; Yamamoto, Kunihiro; Kiyan, Tsuyoshi; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori; サクガワ, タカシ; ヤマグチ, タカヒロ; ヤマモト, クニヒロ; キヤン, ツヨシ; ナミヒラ, タカオ; カツキ, スナオ; アキヤマ, ヒデノリ; 佐久川, 貴志

    2005-01-01

    Pulsed power has been used to produce non-thermal plasmas in gases that generate a high electric field at the tip of streamer discharges, where high energy electrons, free radicals, and ozone are produced. Recently, all solid state pulsed power generators, which are operated with high repetition rate, long lifetime and high reliability, have been developed for industrial applications, such as high repetition rate pulsed gas lasers, high energy density plasma (EUV sources) and water discharges...

  16. Fabrication of FCC Structure Colloidal Photonic Crystals and Characteration of Band-Gap Measured%FCC结构胶体光子晶体的制备及其带隙特性测量

    Institute of Scientific and Technical Information of China (English)

    闫海涛; 王鸣; 葛益娴; 喻平; 刘青

    2009-01-01

    基于对光纤传输特性和胶体光子晶体制备方法的研究,提出了用外加电场控制的方法制备光子带隙位于通讯波段的FCC结构的胶体光子晶体,并用光纤系统测试胶体光子晶体的带隙特性.采用RSOFT模拟了胶体光子晶体的带隙,分析了带隙位于通讯波段时所需的胶体微球的基本参量(微球折射率和直径).采用自组装的方法,用步进电机控制玻璃基片向上的拉升速率.速率为5 μm/s,同时外加一电场.用扫描电镜观测胶体晶体的表面形貌,并设计了单模光纤系统测量胶体光子晶体的带隙特性.测试的透射谱线表明胶体光子晶体的带隙中心波长为1552 nm.测试结果和模拟结果具有很好的一致性,误差只有2 nm.%Based on the transmission characteration of optical fiber and the methods of fabrication colloidal photonic crystals, electric field-controlled method is used to fabricate colloidal photonic crystals with the photonic band-gap (PBG) in communications wavelength. RSOFT is used to simulate PBG characteration of colloidal photonic crystals and the parameters of colloidal microsphere are obtained. By the self-assembled method, the stepping motor is used to control the glass substrate, with the rate of 5 μm/s. At the same time an electric field is applied in the process of the colloidal crystals growth. The scanning electron microscopy is used to observe the surface of colloidal photonic crystals. An optical fiber system is designed to test PBG center wavelength of colloidal photonic crystals. Transmission spectrum shows the PBG of this colloidal crystals at 1552 nm. The agreement is very good between the experimental results and the simulation results, with the error of only 2 nm.

  17. Diode-pumped all-solid-state lasers and applications

    CERN Document Server

    Parsons-Karavassilis, D

    2002-01-01

    This thesis describes research carried out by the within the Physics Department at Imperial College that was aimed at developing novel all-solid-state laser sources and investigating potential applications of this technology. A description of the development, characterisation and application of a microjoule energy level, diode-pumped all-solid-state Cr:LiSGAF femtosecond oscillator and regenerative amplifier system is presented. The femtosecond oscillator was pumped by two commercially available laser diodes and produced an approx 80 MHz pulse train of variable pulse duration with approx 30 mW average output power and a tuning range of over approx 60 nm. This laser oscillator was used to seed a regenerative amplifier, resulting in adjustable repetition rate (single pulse to 20 kHz) approx 1 mu J picosecond pulses. These pulses were compressed to approx 150 fs using a double-pass twin-grating compressor. The amplifier's performance was investigated with respect to two different laser crystals and different pul...

  18. All solid-state SBS phase conjugate mirror

    Science.gov (United States)

    Dane, C.B.; Hackel, L.A.

    1999-03-09

    A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases. 8 figs.

  19. A New All Solid State Approach to Gaseous Pollutant Detection

    Science.gov (United States)

    Brown, V.; Tamstorf, K.

    1971-01-01

    Recent efforts in our laboratories have concentrated on the development of an all solid state gas sensor, by combining solid electrolyte (ion exchange membrane) technology with advanced thin film deposition processes. With the proper bias magnitude and polarity these miniature electro-chemical,cells show remarkable current responses for many common pollution gases. Current activity is now focused on complementing a multiple array (matrix) of these solid state sensors, with a digital electronic scanner device possessing "scan-compare-identify-alarm: capability. This innovative approach to multi-component pollutant gas analysis may indeed be the advanced prototype for the "third generation" class of pollution analysis instrumentation so urgently needed in the decade ahead.

  20. Development of all-solid-state flash x-ray generator with photoconductive semiconductor switches.

    Science.gov (United States)

    Xun, Ma; Jianjun, Deng; Hongwei, Liu; Jianqiang, Yuan; Jinfeng, Liu; Bing, Wei; Yanling, Qing; Wenhui, Han; Lingyun, Wang; Pin, Jiang; Hongtao, Li

    2014-09-01

    A compact, low-jitter, and high repetitive rate all-solid-state flash x-ray generator making use of photo conductive semiconductor switches was developed recently for the diagnostic purpose of some hydrokinetical experiments. The generator consisted of twelve stages of Blumlein pulse forming networks, and an industrial cold cathode diode was used to generate intense x-ray radiations with photon energy up to 220 keV. Test experiments showed that the generator could produce >1 kA electron beam currents and x-ray pulses with ~40 ns duration under 100 Hz repetitive rates at least (limited by the triggering laser on hand), also found was that the delay time of the cathode explosive emission is crucial to the energy transfer efficiency of the whole system. In addition, factors affecting the diode impedance, how the switching synchronization and diode impedance determining the allowable operation voltage were discussed. PMID:25273719

  1. Development of all-solid-state flash x-ray generator with photoconductive semiconductor switches

    Energy Technology Data Exchange (ETDEWEB)

    Xun, Ma; Jianjun, Deng; Hongwei, Liu; Jianqiang, Yuan; Jinfeng, Liu; Bing, Wei; Yanling, Qing; Wenhui, Han; Lingyun, Wang; Pin, Jiang; Hongtao, Li [Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang 621900 (China)

    2014-09-15

    A compact, low-jitter, and high repetitive rate all-solid-state flash x-ray generator making use of photo conductive semiconductor switches was developed recently for the diagnostic purpose of some hydrokinetical experiments. The generator consisted of twelve stages of Blumlein pulse forming networks, and an industrial cold cathode diode was used to generate intense x-ray radiations with photon energy up to 220 keV. Test experiments showed that the generator could produce >1 kA electron beam currents and x-ray pulses with ∼40 ns duration under 100 Hz repetitive rates at least (limited by the triggering laser on hand), also found was that the delay time of the cathode explosive emission is crucial to the energy transfer efficiency of the whole system. In addition, factors affecting the diode impedance, how the switching synchronization and diode impedance determining the allowable operation voltage were discussed.

  2. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying Biomedical Photonics, spectroscopy and microscopy This volume discusses biomedical photonics, spectroscopy and microscopy, the basic physical principles underlying the technology and its applications. The topics discussed in this volume are: Biophotonics; Fluorescence and Phosphorescence; Medical Photonics; Microscopy; Nonlinear Optics; Ophthalmic Technology; Optical Tomography; Optofluidics; Photodynamic Therapy; Image Processing; Imaging Systems; Sensors; Single Molecule Detection; Futurology in Photonics. Comprehensive and accessible cov

  3. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying thescience and technology of nanophotonics, its materials andstructures This volume presents nanophotonic structures and Materials.Nanophotonics is photonic science and technology that utilizeslight/matter interactions on the nanoscale where researchers arediscovering new phenomena and developing techniques that go wellbeyond what is possible with conventional photonics andelectronics.The topics discussed in this volume are: CavityPhotonics; Cold Atoms and Bose-Einstein Condensates; Displays;E-paper; Graphene; Integrated Photonics; Liquid Cry

  4. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    This book covers modern photonics accessibly and discusses the basic physical principles underlying all the applications and technology of photonicsThis volume covers the basic physical principles underlying the technology and all applications of photonics from statistical optics to quantum optics. The topics discussed in this volume are: Photons in perspective; Coherence and Statistical Optics; Complex Light and Singular Optics; Electrodynamics of Dielectric Media; Fast and slow Light; Holography; Multiphoton Processes; Optical Angular Momentum; Optical Forces, Trapping and Manipulation; Pol

  5. Photonics

    CERN Document Server

    Andrews, David L

    2015-01-01

    Discusses the basic physical principles underlying the technology instrumentation of photonics This volume discusses photonics technology and instrumentation. The topics discussed in this volume are: Communication Networks; Data Buffers; Defense and Security Applications; Detectors; Fiber Optics and Amplifiers; Green Photonics; Instrumentation and Metrology; Interferometers; Light-Harvesting Materials; Logic Devices; Optical Communications; Remote Sensing; Solar Energy; Solid-State Lighting; Wavelength Conversion Comprehensive and accessible coverage of the whole of modern photonics Emphas

  6. Tunable All-Solid-State Local Oscillators to 1900 GHz

    Science.gov (United States)

    Ward, John; Chattopadhyay, Goutam; Maestrini, Alain; Schlecht, Erich; Gill, John; Javadi, Hamid; Pukala, David; Maiwald, Frank; Mehdi, Imran

    2004-01-01

    We present a status report of an ongoing effort to develop robust tunable all-solid-state sources up to 1900 GHz for the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory. GaAs based multi-chip power amplifier modules at W-band are used to drive cascaded chains of multipliers. We have demonstrated performance from chains comprised of four doublers up to 1600 GHz as well as from a x2x3x3 chain to 1900 GHz. Measured peak output power of 23 (micro)W at 1782 GHz and 2.6 (micro)W at 1900 GHz has been achieved when the multipliers are cooled to 120K. The 1900 GHz tripler was pumped with a four anode tripler that produces a peak of 4 mW at 630 GHz when cooled to 120 K. We believe that these sources can now be used to pump hot electron bolometer (HEB) heterodyne mixers.ter (HEB) heterodyne mixers.

  7. Ultrafast photonic crystal optical switching

    Institute of Scientific and Technical Information of China (English)

    GONG Qi-huang; HU Xiao-yong

    2006-01-01

    Photonic crystal,a novel and artificial photonic material with periodic dielectric distribution,possesses photonic bandgap and can control the propagation states of photons.Photonic crystal has been considered to be a promising candidate for the future integrated photonic devices.The properties and the fabrication method of photonic crystal are expounded.The progresses of the study of ultrafast photonic crystal optical switching are discussed in detail.

  8. 介质阻挡放电中一维等离子体光子晶体及其带隙特性%One-dimensional plasma photonic crystals in dielectric barrier discharge and its photonic bandgaps

    Institute of Scientific and Technical Information of China (English)

    范伟丽; 董丽芳

    2012-01-01

    A tunable one-dimensional plasma photonic crystal has been obtained in argon dielectric barrier discharge with two water electrodes at atmospheric pressure. The dispersion relation of the plasma photonic crystals is studied by solving a stationary Maxwell wave equation with a method analogous to Kronig-Penney's problem in quantum mechanics. Based on the experimental data, the influence of the parameters including the lattice constant, the length ratio of the plasma and dielectric and electron density on the band diagrams of the plasma photonic crystals is discussed. Results show that the position of the photonic bands is lowered and the phase velocity is reduced when the lattice constant is increased. For the same lattice constants, larger ratio of the plasma with the dielectric leads to the increase of the band gaps and higher band frequencies. The plasma photonic crystals will show wide band gaps when the electron density is larger than 1020 m-3.%在双水电极大气压氩气介质阻挡放电中获得了一维可调等离子体光子晶体.通过类似于量子力学Kronig-Penney模型求解周期势的方法,求解Maxwell方程得到了一维等离子光子晶体的色散关系.结合实验数据,理论模拟了晶格常数、等离子体与介质的厚度比、电子密度等不同参数对等离子体光子晶体带隙的影响.结果表明:等离子体光子晶体晶格常数的增大导致能级位置降低,相速度减小;在相同的晶格常数下,等离子体填充比增大时,带隙位置将略有上升且光子带隙数目增加;当电子密度大于1020 m-3时,等离子体光子晶体具有显著禁带宽度.

  9. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D;

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  10. An all-solid-state, WDM silicon photonic digital link for chip-to-chip communications.

    Science.gov (United States)

    Thacker, Hiren D; Zheng, Xuezhe; Lexau, Jon; Shafiiha, Roshanak; Shubin, Ivan; Lin, Shiyun; Djordjevic, Stevan; Amberg, Philip; Chang, Eric; Liu, Frankie; Simons, John; Lee, Jin-Hyoung; Abed, Arin; Liang, Hong; Luo, Ying; Yao, Jin; Feng, Dazeng; Asghari, Mehdi; Ho, Ron; Raj, Kannan; Cunningham, John E; Krishnamoorthy, Ashok V

    2015-05-18

    We describe a multiwavelength hybrid-integrated solid-state link on a 3 µm silicon-on-insulator (SOI) nanophotonic platform. The link spans three chips and employs germanium-silicon electroabsorption waveguide modulators, silicon transport waveguides, echelle gratings for multiplexing and demultiplexing, and pure germanium waveguide photo-detectors. The 8λ WDM Tx and Rx components are interconnected via a routing "bridge" chip using edge-coupled optical proximity communication. The packaged, retimed digital WDM link is demonstrated at 10 Gb/s and 10(-12) BER, with three wavelength channels consuming an on-chip power below 1.5 pJ/bit, excluding the external laser power.

  11. 基于高阻抗表面PBG结构微带天线的设计与分析%Design and Analysis of Microstrip Antenna Based on Photonic Band-gap Structure with High Impedance Surface

    Institute of Scientific and Technical Information of China (English)

    汪仲清; 彭丽丹; 李宝; 徐荣森

    2013-01-01

    以高介电常数介质为基底,利用辐射贴片开槽和微带馈电技术,设计了一款尺寸仅为16 mm×12.45 mm的小型微带天线.通过在此天线微带贴片周围加载高阻抗表面型光子晶体,有效抑制了表面波,改善了以高介电常数介质为基底的贴片天线的性能,实现了一款多频小型化PBG天线.HFSS仿真结果表明,加载高阻抗表面结构后的微带天线出现了三个谐振频点,分别为2.74、2.86和3.80 GHz,其对应的增益分别达到6.02、8.38和5.69 dB.所设计的光子晶体天线物理尺寸较小,方向性良好且具有多频特性,因此可为实际通信天线的应用提供参考.%Based on dielectric substrate with high dielectric constant,a miniaturized microstrip antenna with the size of only 16 mm× 12.45 mm was designed with the techniques of grooving the patch and microstrip feed.By loading the high impedance surface around the patch,the surface wave was suppressed effectively and the antenna performance was improved,then a multi-frequency and miniaturized antenna based on photonic band-gap (PBG) was realized.Simulation results obtained by HFSS show that,the microstrip antenna based on high impedance surface structure has three resonant frequencies:2.74 GHz,2.86 GHz and 3.80 GHz,and the corresponding gains are 6.02 dB,8.83 dB and 5.69 dB,respectively.The antenna based on PBG owns the characteristics of smaller size,good radiation performance and multi-frequency,which can provide reference for practical communication applications.

  12. Photonic bandgap fibers: theory and experiments

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Libori, Stig E. Barkou

    2000-01-01

    We will in this presentation address, show how the fiber cladding structure influences the resulting waveguiding properties. The core may be introduced by breaking the periodicity of the air holes at the center of the fiber. It has been demonstrated experimentally that this makes it possible to...

  13. Liquid Crystal photonic Bandgap Fiber Devices

    DEFF Research Database (Denmark)

    Wei, Lei

    . A polarizer with electrically tunable polarization extinction ratio is obtained. An on-chip tunable notch filter based on long-period gratings is presented, exhibiting high polarization sensitivity. A tunable polarization controller using negative dielectric LCs is developed, which can be thermally...... and electrically controlled to work both as a quarter-wave plate or half-wave plate. An electrically tunable bandpass filter based on two solid-core PCFs filled with different LCs is fabricated, and the tunability of the bandwidth is achieved by individually or simultaneously controlling the driving voltage...

  14. Large Bandgap Semiconductors for Solar Water Splitting

    DEFF Research Database (Denmark)

    Malizia, Mauro

    water splitting devices having tandem design. The increase of the photovoltage produced by GaP under illumination was the main goal of this work. GaP has a bandgap of 2.25 eV and could in theory produce a photovoltage of approximately 1.7 V. Instead, the photovoltage produced by the semiconductor...... density generated by GaP was increased by more than 60% by electrochemical etching of the surface. The etching process produces a rough microstructured surface that increases the optical path length of the incident photons and the collection of photogenerated electrons.Furthermore, the synthesis of BiVO4...

  15. Wide Bandgap Extrinsic Photoconductive Switches

    Science.gov (United States)

    Sullivan, James Stephen

    Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The

  16. Recent progress in all-solid-state quantum dot-sensitized TiO{sub 2} nanotube array solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qingyao, E-mail: wangqingyao0532@163.com [Ludong University, School of Chemistry and Materials Science (China); Chen, Chao; Liu, Wei [Tongji University, School of Materials Science and Engineering (China); Gao, Shanmin [Ludong University, School of Chemistry and Materials Science (China); Yang, Xiuchun, E-mail: yangxc@tongji.edu.cn [Tongji University, School of Materials Science and Engineering (China)

    2016-01-15

    All-solid-state quantum dot-sensitized TiO{sub 2} nanotube array solar cells have been drawing great attention to solar energy conversion, which break through restrictions in traditional solar cells, such as the high recombination at interfaces of porous TiO{sub 2} films/sensitizers/hole conductors/counter electrodes, instability of dyes, and leakage of solution electrolyte, and so the novel solar cells exhibit promising applications in the future. In this Minireview article, the assembling of solar cells including the preparation of TiO{sub 2} nanotube array photoanodes, quantum dot preparation and sensitization on photoanodes, filling of hole conductors in TiO{sub 2} nanotubes, and selection of counter electrodes are overviewed, and the development course of all-solid-state quantum dot-sensitized TiO{sub 2} nanotube array solar cells in recent years are summarized in detail. Moreover, the influences of TiO{sub 2} nanotube array photoanodes, quantum dots, solid electrolyte, and counter electrodes on photon-to-current efficiencies of solar cells are summarized. In addition, current problems of solid-state quantum dot-sensitized TiO{sub 2} nanotube array solar cells are analyzed, and the corresponding improvements, such as multisensitizers and passivation layers, are proposed to improve the photoelectric conversion efficiency. Finally, this Minireview provides a perspective for the future development of this novel solar cell.

  17. Recent progress in all-solid-state quantum dot-sensitized TiO2 nanotube array solar cells

    International Nuclear Information System (INIS)

    All-solid-state quantum dot-sensitized TiO2 nanotube array solar cells have been drawing great attention to solar energy conversion, which break through restrictions in traditional solar cells, such as the high recombination at interfaces of porous TiO2 films/sensitizers/hole conductors/counter electrodes, instability of dyes, and leakage of solution electrolyte, and so the novel solar cells exhibit promising applications in the future. In this Minireview article, the assembling of solar cells including the preparation of TiO2 nanotube array photoanodes, quantum dot preparation and sensitization on photoanodes, filling of hole conductors in TiO2 nanotubes, and selection of counter electrodes are overviewed, and the development course of all-solid-state quantum dot-sensitized TiO2 nanotube array solar cells in recent years are summarized in detail. Moreover, the influences of TiO2 nanotube array photoanodes, quantum dots, solid electrolyte, and counter electrodes on photon-to-current efficiencies of solar cells are summarized. In addition, current problems of solid-state quantum dot-sensitized TiO2 nanotube array solar cells are analyzed, and the corresponding improvements, such as multisensitizers and passivation layers, are proposed to improve the photoelectric conversion efficiency. Finally, this Minireview provides a perspective for the future development of this novel solar cell

  18. Optical Fiber Lasers and All Solid-State Passively Modulated Microchip Lasers

    Institute of Scientific and Technical Information of China (English)

    Junewen; Chen; Pie-Yau; Chien; Yu-Ting; Lee

    2003-01-01

    Erbium fiber lasers of continuous mode outputs and of pulsed picosecond and sub-picosecond pulses train are reported. Compact all solid state passively modulated microchip lasers are also developed to the same degree.

  19. Development of an All Solid High Energy Density Space Rated Battery Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Quallion's intends to develop an all-solid 600 Wh/kg, flexible form-factor lithium rechargeable energy device for advanced space power applications. Quallion's...

  20. Light and gas confinement in hollow-core photonic crystal fibre based photonic microcells

    DEFF Research Database (Denmark)

    Benabid, F.; Roberts, John; Couny, F.;

    2009-01-01

    guides via a photonic bandgap and the other guides by virtue of an inhibited coupling between core and cladding mode constituents. For the former fibre type, we explore how the bandgap is formed using a photonic analogue of the tight-binding model and how it is related to the anti-resonant reflection...

  1. Compressed lead-based perovskites reaching optimal Shockley-Queisser bandgap with prolonged carrier lifetime

    CERN Document Server

    Liu, Gang; Gong, Jue; Yang, Wenge; Mao, Ho-kwang; Liu, Zhenxian; Schaller, Richard D; Zhang, Dongzhou; Xu, Tao

    2016-01-01

    Atomic structure of materials plays a decisive role in the light-matter interaction. Yet, despite its unprecedented progress, further efficiency boost of Lead-based organic-inorganic perovskite solar cells is hampered by its greater bandgap than the optimum value according to Shockley-Queisser limit. Here, we report the experimental achievement of bandgap narrowing in formamidinium lead triiodide from 1.489 to 1.337 eV by modulating the lattice constants under hydraulic compression, reaching the optimized bandgap for single-junction solar cells. Strikingly, such bandgap narrowing is accomplished with improved, instead of sacrificed carrier lifetime. More attractively, the narrowed bandgap is partially retainable after the release of pressure. This work opens a new dimension in basic science understanding of structural photonics and paves an alternative pathway towards more efficient photovoltaic materials.

  2. 光导在折射率引导光纤、多孔光纤、光子带隙光纤和纳米线中的简要定性解释%Simple qualitative explanations for light guidance in index-guiding fibres, holey fibres, photonic band-gap fibres and nanowires

    Institute of Scientific and Technical Information of China (English)

    LOVE John

    2014-01-01

    本文是一篇教学论文,旨在通过对具体实例中不同物理过程的分析来定性解释光导拓宽固体材料折射率引导光纤光谱、多孔光纤光谱、光子带隙光纤光谱和纳米线光谱的原理。%This is a tutorial-style paper in which simple explanations are presented to provide qualitative in-sight into the different physical processes that account for the guidance of light in the broadening spectrum of fibre types.These types include solid-material index-guiding fibres, holey fibres, photonic band-gap fibres and nano-wires.

  3. Wide-Bandgap Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, M.S.

    2005-11-22

    With the increase in demand for more efficient, higher-power, and higher-temperature operation of power converters, design engineers face the challenge of increasing the efficiency and power density of converters [1, 2]. Development in power semiconductors is vital for achieving the design goals set by the industry. Silicon (Si) power devices have reached their theoretical limits in terms of higher-temperature and higher-power operation by virtue of the physical properties of the material. To overcome these limitations, research has focused on wide-bandgap materials such as silicon carbide (SiC), gallium nitride (GaN), and diamond because of their superior material advantages such as large bandgap, high thermal conductivity, and high critical breakdown field strength. Diamond is the ultimate material for power devices because of its greater than tenfold improvement in electrical properties compared with silicon; however, it is more suited for higher-voltage (grid level) higher-power applications based on the intrinsic properties of the material [3]. GaN and SiC power devices have similar performance improvements over Si power devices. GaN performs only slightly better than SiC. Both SiC and GaN have processing issues that need to be resolved before they can seriously challenge Si power devices; however, SiC is at a more technically advanced stage than GaN. SiC is considered to be the best transition material for future power devices before high-power diamond device technology matures. Since SiC power devices have lower losses than Si devices, SiC-based power converters are more efficient. With the high-temperature operation capability of SiC, thermal management requirements are reduced; therefore, a smaller heat sink would be sufficient. In addition, since SiC power devices can be switched at higher frequencies, smaller passive components are required in power converters. Smaller heat sinks and passive components result in higher-power-density power converters

  4. Low-bandgap, monolithic, multi-bandgap, optoelectronic devices

    Science.gov (United States)

    Wanlass, Mark W.; Carapella, Jeffrey J.

    2014-07-08

    Low bandgap, monolithic, multi-bandgap, optoelectronic devices (10), including PV converters, photodetectors, and LED's, have lattice-matched (LM), double-heterostructure (DH), low-bandgap GaInAs(P) subcells (22, 24) including those that are lattice-mismatched (LMM) to InP, grown on an InP substrate (26) by use of at least one graded lattice constant transition layer (20) of InAsP positioned somewhere between the InP substrate (26) and the LMM subcell(s) (22, 24). These devices are monofacial (10) or bifacial (80) and include monolithic, integrated, modules (MIMs) (190) with a plurality of voltage-matched subcell circuits (262, 264, 266, 270, 272) as well as other variations and embodiments.

  5. Two-dimensional Kagomé Structure, Fundamental Hexagonal Photonic Crystal Configuration

    DEFF Research Database (Denmark)

    Nielsen, J.B.; Søndergaard, Thomas; Barkou, Stig Eigil;

    1999-01-01

    The photonic bandgap properties of the two-dimensional hexagonal Kagomé structure have been investigated. Large TM bandgaps are found in a GaAs rod in an air configuration example.......The photonic bandgap properties of the two-dimensional hexagonal Kagomé structure have been investigated. Large TM bandgaps are found in a GaAs rod in an air configuration example....

  6. Efficient all solid-state continuous-wave yellow-orange light source

    DEFF Research Database (Denmark)

    Janousek, Jiri; Johansson, Sandra; Tidemand-Lichtenberg, Peter;

    2005-01-01

    We present highly efficient sum-frequency generation between two CW IR lasers using periodically poled KTP. The system is based on the 1064 and 1342 nm laser-lines of two Nd:YVO4 lasers. This is an all solid-state light source in the yellow-orange spectral range. The system is optimized in terms...

  7. Room-temperature single-photon sources based on nanocrystal fluorescence in photonic/plasmonic nanostructures

    Science.gov (United States)

    Lukishova, S. G.; Winkler, J. M.; Bissell, L. J.; Mihaylova, D.; Liapis, Andreas C.; Shi, Z.; Goldberg, D.; Menon, V. M.; Boyd, R. W.; Chen, G.; Prasad, P.

    2014-10-01

    Results are presented here towards robust room-temperature SPSs based on fluorescence in nanocrystals: colloidal quantum dots, color-center diamonds and doped with trivalent rare-earth ions (TR3+). We used cholesteric chiral photonic bandgap and Bragg-reflector microcavities for single emitter fluorescence enhancement. We also developed plasmonic bowtie nanoantennas and 2D-Si-photonic bandgap microcavities. The paper also provides short outlines of other technologies for room-temperature single-photon sources.

  8. Resonant add-drop filter based on a photonic quasicrystal

    DEFF Research Database (Denmark)

    Romero-Vivas, J.; Chigrin, D. N.; Lavrinenko, Andrei;

    2005-01-01

    We present a numerical study of optical properties of an octagonal quasi-periodic lattice of dielectric rods. We report on a complete photonic bandgap in TM polarization up to extremely low dielectric constants of rods. The first photonic bandgap remains open down to dielectric constant as small ...

  9. Spatial filtering with photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Maigyte, Lina [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Staliunas, Kestutis [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Rambla Sant Nebridi 22, Terrassa 08222 (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, Barcelona 08010 (Spain)

    2015-03-15

    Photonic crystals are well known for their celebrated photonic band-gaps—the forbidden frequency ranges, for which the light waves cannot propagate through the structure. The frequency (or chromatic) band-gaps of photonic crystals can be utilized for frequency filtering. In analogy to the chromatic band-gaps and the frequency filtering, the angular band-gaps and the angular (spatial) filtering are also possible in photonic crystals. In this article, we review the recent advances of the spatial filtering using the photonic crystals in different propagation regimes and for different geometries. We review the most evident configuration of filtering in Bragg regime (with the back-reflection—i.e., in the configuration with band-gaps) as well as in Laue regime (with forward deflection—i.e., in the configuration without band-gaps). We explore the spatial filtering in crystals with different symmetries, including axisymmetric crystals; we discuss the role of chirping, i.e., the dependence of the longitudinal period along the structure. We also review the experimental techniques to fabricate the photonic crystals and numerical techniques to explore the spatial filtering. Finally, we discuss several implementations of such filters for intracavity spatial filtering.

  10. 2-Photon tandem device for water splitting

    DEFF Research Database (Denmark)

    Seger, Brian; Castelli, Ivano Eligio; Vesborg, Peter Christian Kjærgaard;

    2014-01-01

    Within the field Of photocatalytic water splitting there are several strategies to achieve the goal of efficient and cheap photocatalytic water splitting. This work examines one particular strategy by focusing on monolithically stacked, two-photon photoelectrochemical cells. The overall aim...... for photocatalytic water splitting by using a large bandgap photocathode and a low bandgap photoanode with attached protection layers....

  11. High Reversibility of Soft Electrode Materials in All-solid-state Batteries

    Directory of Open Access Journals (Sweden)

    Atsushi eSakuda

    2016-05-01

    Full Text Available All-solid-state batteries using inorganic solid electrolytes (SEs are considered to be ideal batteries for electric vehicles (EVs and plug-in hybrid electric vehicles (PHEVs because they are potentially safer than conventional lithium-ion batteries (LIBs. In addition, all-solid-state batteries are expected to have long battery lives owing to the inhibition of chemical side reactions because only lithium ions move through the typically used inorganic SEs. The development of high-energy (more than 300 Wh kg-1 secondary batteries has been eagerly anticipated for years. The application of high-capacity electrode active materials is essential for fabricating such batteries. Recently, we proposed metal polysulfides as new electrode materials. These materials show higher conductivity and density than sulfur, which is advantageous for fabricating batteries with relatively higher energy density. Lithium niobium sulfides, such as Li3NbS4, have relatively high density, conductivity, and rate capability among metal polysulfide materials, and batteries with these materials have capacities high enough to potentially exceed the gravimetric energy density of conventional LIBs.Favorable solid-solid contact between the electrode and electrolyte particles is a key factor for fabricating high performance all-solid-state batteries. Conventional oxide-based positive electrode materials tend to be given rise to cracks during fabrication and/or charge-discharge processes. Here we report all-solid-state cells using lithium niobium sulfide as a positive electrode material, where favorable solid-solid contact was established by using lithium sulfide electrode materials because of their high processability. Cracks were barely observed in the electrode particles in the all-solid-state cells before or after charging and discharging with a high capacity of approx. 400 mAh g-1, suggesting that the lithium niobium sulfide electrode charged and discharged without experiencing

  12. New Light-Harvesting Materials Using Accurate and Efficient Bandgap Calculations

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Hüser, Falco; Pandey, Mohnish;

    2014-01-01

    Electronic bandgap calculations are presented for 2400 experimentally known materials from the Materials Project database and the bandgaps, obtained with different types of functionals within density functional theory and (partial) self-consistent GW approximation, are compared for 20 randomly...... chosen compounds forming an unconventional set of ternary and quaternary materials. It is shown that the computationally cheap GLLB-SC potential gives results in good agreement (around 15%) with the more advanced and demanding eigenvalue-self-consistent GW. This allows for a high-throughput screening...... of materials for different applications where the bandgaps are used as descriptors for the efficiency of a photoelectrochemical device. Here, new light harvesting materials are proposed to be used in a one-photon photoelectrochemical device for water splitting by combining the estimation of the bandgaps...

  13. Fluorine-Doped Antiperovskite Electrolyte for All-Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Li, Yutao; Zhou, Weidong; Xin, Sen; Li, Shuai; Zhu, Jinlong; Lü, Xujie; Cui, Zhiming; Jia, Quanxi; Zhou, Jianshi; Zhao, Yusheng; Goodenough, John B

    2016-08-16

    A fluorine-doped antiperovskite Li-ion conductor Li2 (OH)X (X=Cl, Br) is shown to be a promising candidate for a solid electrolyte in an all-solid-state Li-ion rechargeable battery. Substitution of F(-) for OH(-) transforms orthorhombic Li2 OHCl to a room-temperature cubic phase, which shows electrochemical stability to 9 V versus Li(+) /Li and two orders of magnitude higher Li-ion conductivity than that of orthorhombic Li2 OHCl. An all-solid-state Li/LiFePO4 with F-doped Li2 OHCl as the solid electrolyte showed good cyclability and a high coulombic efficiency over 40 charge/discharge cycles. PMID:27356953

  14. All-solid-state narrow-linewidth 455-nm blue laser based on Ti: sapphire crystal

    Institute of Scientific and Technical Information of China (English)

    Shankui Rong; Xiaolei Zhu; Weibiao Chen

    2009-01-01

    A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti:sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd:YAG laser and injection-seeded by an external cavity laser diode, the narrow-linewidth 910-nm laser with pulse width of 20 ns is obtained from a Tirsapphire laser. 3.43-mJ blue laser can be obtained from the laser system by frequency-doubling with BBO crystal. This research is very useful to determine the roadmap of developing the practical, high power blue laser. This kind of laser will have potential application for underwater communication.

  15. Oxide-ceramic electrolyte layers for all-solid-state lithium batteries

    OpenAIRE

    Reppert, Thorsten; Tsai, Chih-Long; Finsterbusch, Martin; Uhlenbruck, Sven; Guillon, Olivier; Bram, Martin

    2015-01-01

    In the past decade, electricity generated from renewable energy sources, as well as electro mobility have gained much importance in our society. With this readiness to change the current system, an increase of requirements for electric grid and safety aspects of energy storage systems appear. All-solid-state lithium batteries (ASB) have better safety properties due to the non-flammable solid electrolyte than common lithium ion batteries (LIB), which use flammable organic liquid as electrolyte...

  16. An rf system using all-solid-state amplifiers for the JAERI FEL

    Science.gov (United States)

    Sawamura, M.; Ohkubo, M.; Minehara, E.; Nagai, R.; Takao, M.; Kikuzawa, N.; Sugimoto, M.; Suzuki, Y.; Kawarasaki, Y.; Nagatsuka, K.; Sato, K.; Matsumoto, H.; Kashiwagi, A.

    1993-07-01

    The JAERI FEL linac is energized with four kinds of all-solid-state amplifiers having 5, 1.5, 4, and 50 kW of peak power with a 1-2 ms pulse length. Amplitude and phase stabilities of the 50 kW amplifiers are ˜ 1% and ˜1°, respectively. A feed-forward loop circuit is effective when a feedback loop circuit is not able to stabilize the output of rf power.

  17. Sub-micrometer-thick all-solid-state supercapacitors with high power and energy densities

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanhui [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, and School of Chemistry and Chemical Engineering, Shandong University, Jinan 250061 (China); Ding, Yi [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, and School of Chemistry and Chemical Engineering, Shandong University, Jinan 250061 (China); Shandong Applied Research Center for Gold Technology (Au-SDARC), Yantai 264005 (China)

    2011-09-15

    A sub-micrometer-thick, flexible, all-solid-state supercapacitor is fabricated. Through simultaneous realization of high dispersity of pseudocapacitance materials and quick electrode response, the hybrid nanostructures show enhanced volumetric capacitance and excellent stability, as well as very high power and energy densities. This suggests their potential as next-generation, high-performance energy conversion and storage devices for wearable electronics. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. High repetition rate, compact micro-pulse all-solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Yutong Feng; Junqing Meng; Weibiao Chen

    2007-01-01

    A high repetition rate, compact micro-pulse all-solid-state laser is designed. The diffusion bonded crystal of YAG, Nd:YAG, and Cr4+:YAG is taken as a monolithic cavity. The optimized initial transmission,output coupling, and pumping size of Cr4+:YAG are calculated. The experimental results show that the laser satisfies the requirement of a spaceborne laser range finder.

  19. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    OpenAIRE

    Luca Porcarelli; Claudio Gerbaldi; Federico Bella; Jijeesh Ravi Nair

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene o...

  20. Comprehensive characterization of all-solid-state thin films commercial microbatteries by Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Larfaillou, S.; Guy-Bouyssou, D.; le Cras, F.; Franger, S.

    2016-07-01

    Constant miniaturization of electronic devices opens the way to the development of thin film microbatteries (TFB). For this type of devices, the use of an all-solid-state thin film technology has many advantages over conventional lithium cells. These microbatteries are thin, bendable and can be produced with a customizable shape for integration in microelectronic devices. Moreover, without liquid electrolyte, they are safer. With the aim to support the industrial production of these TFBs, adequate tools for understanding the electrochemical behavior of the complete microbattery and the identification of their possible failures that can occur have to be developed. In this context, the Electrochemical Impedance Spectroscopy seems to be a good compromise for cells characterization. Widely used for the characterization of liquid electrolyte-based batteries, this technique has been less applied to all solid state batteries, mainly because of the difficulty to work with a two-electrode system. There has been no comprehensive study deeply explaining the impedance evolution during the entire life of a microbattery. In this paper, physical characterizations of individual active materials and aging experiments have been performed in order to undoubtedly assign each EIS contributions, and to propose a more comprehensive electrical model for this family of commercial all-solid-state microbatteries.

  1. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Univ. of California, Davis, CA (United States)

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  2. Photonic band gap of 2D complex lattice photonic crystal

    Institute of Scientific and Technical Information of China (English)

    GUAN Chun-ying; YUAN Li-bo

    2009-01-01

    It is of great significance to present a photonic crystal lattice structure with a wide photonic bandgap. A two-dimension complex lattice photonic crystal is proposed. The photonic crystal is composed of complex lattices with triangular structure, and each single cell is surrounded by six scatterers in an hexagon. The photonic band gaps are calculated based on the plane wave expansion (PWE) method. The results indicate that the photonic crystal has tunable large TM polarization band gap, and a gap-midgap ratio of up to 45.6%.

  3. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  4. Ultrahigh photoconductivity of bandgap-graded CdSxSe1‑x nanowires probed by terahertz spectroscopy

    Science.gov (United States)

    Liu, Hongwei; Lu, Junpeng; Yang, Zongyin; Teng, Jinghua; Ke, Lin; Zhang, Xinhai; Tong, Limin; Sow, Chorng Haur

    2016-06-01

    Superiorly high photoconductivity is desirable in optoelectronic materials and devices for information transmission and processing. Achieving high photoconductivity via bandgap engineering in a bandgap-graded semiconductor nanowire has been proposed as a potential strategy. In this work, we report the ultrahigh photoconductivity of bandgap-graded CdSxSe1‑x nanowires and its detailed analysis by means of ultrafast optical-pump terahertz-probe (OPTP) spectroscopy. The recombination rates and carrier mobility are quantitatively obtained via investigation of the transient carrier dynamics in the nanowires. By analysis of the terahertz (THz) spectra, we obtain an insight into the bandgap gradient and band alignment to carrier transport along the nanowires. The demonstration of the ultrahigh photoconductivity makes bandgap-graded CdSxSe1‑x nanowires a promising candidate as building blocks for nanoscale electronic and photonic devices.

  5. Photonic crystals in epitaxial semiconductors

    CERN Document Server

    La Rue, R M de

    1998-01-01

    The title of the paper uses the expression "photonic crystals". By photonic crystals, we mean regular periodic structures with a substantial refractive index variation in one-, two- or three- dimensional space. Such crystals can $9 exist naturally, for example natural opal, but are more typically fabricated by people. Under sufficiently strong conditions, i.e., sufficiently large refractive index modulation, correct size of structural components, and $9 appropriate rotational and translational symmetry, these crystals exhibit the characteristics of a photonic bandgap (PBG) structure. In a full photonic bandgap structure there is a spectral stop band for electromagnetic waves $9 propagating in any direction through the structure and with an arbitrary state of polarization. This behavior is of interest both from a fundamental viewpoint and from the point of view of novel applications in photonic devices. The $9 paper gives an outline review of work on photonic crystals carried out by the Optoelectronics Researc...

  6. Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions

    OpenAIRE

    Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

    2010-01-01

    One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with incr...

  7. Nitrogen dissociation during RF sputtering of Lipon electrolyte for all-solid-states batteries

    DEFF Research Database (Denmark)

    Stamate, Eugen; Christiansen, Ane Sælland; Holtappels, Peter

    2013-01-01

    phosphorus oxynitride (Lipon), that can be compacted with the anode and cathode electrodes in an all-solid-states structure where the nitrogen incorporation is considered one of the key parameters for controlling the ionic conductivity. In this work the nitrogen dissociation during RF sputtering of Lipon......Small size and high power density secondary batteries are desired for a large number of applications based on miniature wireless devices and sensors that need to be compatible with the microelectronic fabrication technology. This fact resulted in the development of solid electrolytes, like lithium...

  8. High power, broadly tunable all-solid-state synchronously-pumped lithium triborate optical parametric oscillator

    OpenAIRE

    Butterworth, S.D.; Girard, S; Hanna, D.C.

    1995-01-01

    The performance of a high-power all-solid-state synchronously-pumped optical parametric oscillator (OPO) based on a Brewster-angled lithium triborate (LBO) crystal is reported. The pump scheme includes a diode-pumped amplifier stage to boost the mean output power from an additive-pulse mode-locked Nd:YLF laser by a factor of two. Improvements in the efficiency of an external resonant frequency-doubler have produced a useful output power of 660mW at 523.5µm for pumping the OPO. Temperature-tun...

  9. An all-solid-state laser source at 671 nm for cold atom experiments with lithium

    OpenAIRE

    Eismann, U.; Gerbier, F.; Canalias, C.; Zukauskas, A.; Trénec, G.; Vigué, J.; Chevy, F.; Salomon, C.

    2012-01-01

    International audience We present an all solid-state narrow line\\-width laser source emitting $670\\,\\mathrm{mW}$ output power at $671\\,\\mathrm{nm}$ delivered in a diffraction-limited beam. The \\linebreak source is based on a fre\\-quency-doubled diode-end-\\linebreak pumped ring laser operating on the ${^4F}_{3/2} \\rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled po\\-tassium titanyl phosphate (ppKTP) in an external build\\-up cavity, doubling efficiencies of up t...

  10. All-solid-state lithium batteries with inorganic solid electrolytes: Review of fundamental science

    Science.gov (United States)

    Xiayin, Yao; Bingxin, Huang; Jingyun, Yin; Gang, Peng; Zhen, Huang; Chao, Gao; Deng, Liu; Xiaoxiong, Xu

    2016-01-01

    The scientific basis of all-solid-state lithium batteries with inorganic solid electrolytes is reviewed briefly, touching upon solid electrolytes, electrode materials, electrolyte/electrode interface phenomena, fabrication, and evaluation. The challenges and prospects are outlined as well. Project supported by the National High Technology Research and Development Program of China (Grant No. 2013AA050906), the National Natural Science Foundation of China (Grant Nos. 51172250 and 51202265), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09010201), and Zhejiang Province Key Science and Technology Innovation Team, China (Grant No. 2013PT16).

  11. All solid-state, injection-seeded Ti: sapphire ring laser

    Institute of Scientific and Technical Information of China (English)

    Ting Yu; Weibiao Chen; Jun Zhou; Jinzi Bi; Junwen Cui

    2005-01-01

    @@ In this letter, we present an all solid-state, injection-seeded Ti:sapphire laser. The laser is pumped by a laser diode pumped frequency-doubled Nd:YAG laser, and injection-seeded by an external cavity laser diode with the wavelength between 770 and 780 nm. The single longitude mode and the doubling efficiency of the laser are obtained after injection seeding. The experimental setup and relative results are reported.It is a good candidate laser source for mobile differential absorption lidar (DIAL) system.

  12. Development of Spintronic Bandgap Materials

    Energy Technology Data Exchange (ETDEWEB)

    Levy, Jeremy; Awschalom, David; Floro, Jerrold

    2014-02-16

    The development of Ge/Si quantum dots with high spatial precision has been pursued, with the goal of developing a platform for “spintronics bandgap materials”. Quantum dots assemblies were grown by molecular beam epitaxy on carbon-templated silicon substrates. These structures were characterized by atomic force microscopy. Vertically gated structures were created on systems with up to six well-defined quantum dots with a controlled geometric arrangement, and low-temperature (mK) transport experiments were performed. These experiments showed evidence for a crossover from diamagnetic to Zeeman energy shifts in resonant tunneling of electrons through electronic states in the quantum dots.

  13. Photonics: practically there?

    Directory of Open Access Journals (Sweden)

    Paula Gould

    2002-09-01

    Strange things happen to light when it passes through photonic crystals. A significant variation in refractive index between the material’s periodic lattice structure and its substrate traps transmitted photons in either one area or the other, creating distinct ‘allowed’ and ‘forbidden’ energy regions. Light with wavelengths equivalent to the forbidden region, the so-called photonic bandgap, is stopped from passing further. Wavelengths from the rest of the electromagnetic spectrum, on the other hand, are free to continue their passage through the material unhindered. In effect, the material is able to halt the passage of light just as the periodic potential of semiconductors, such as silicon, bars electrons from occupying the forbidden energy bandgap.

  14. An all-solid-state lithium-sulfur battery using two solid electrolytes having different functions

    Science.gov (United States)

    Nagata, Hiroshi; Chikusa, Yasuo

    2016-10-01

    All-solid-state lithium-sulfur batteries are expected to be valuable next generation batteries. To improve the performance of all-solid-state lithium-sulfur batteries, it is essential to raise both the reactivity of sulfur and the ionic conductivity of the positive composite electrode. For achieving this, we investigate a positive composite electrode prepared using P2S5 and a solid electrolyte with a high ionic conductivity. As a result, we have found that the lithium-sulfur cell exhibits a relatively low activation energy together with high ionic conductivity. The positive composite electrode exhibits an extremely high capacity of 1550 mA h g-1 (sulfur) at 1.3 mA cm-2 and 25 °C. Moreover, when using the positive electrode, the energy densities at the cell level (18650) are 540 W h kg-1 and 990 W h L-1, estimated from the equivalent structure of a current lithium-ion battery.

  15. All-Solid-State UV Transmitter Development for Ozone Sensing Applications

    Science.gov (United States)

    Prasad, Narasimha S.; Singh, Upendra N.; Armstrong, Darrell Jr.

    2009-01-01

    In this paper, recent progress made in the development of an all-solid-state UV transmitter suitable for ozone sensing applications from space based platforms is discussed. A nonlinear optics based UV setup based on Rotated Image Singly Resonant Twisted Rectangle (RISTRA) optical parametric oscillator (OPO) module was effectively coupled to a diode pumped, single longitudinal mode, conductively cooled, short-pulsed, high-energy Nd:YAG laser operating at 1064 nm with 50 Hz PRF. An estimated 10 mJ/pulse with 10% conversion efficiency at 320 nm has been demonstrated limited only by the pump pulse spatial profile. The current arrangement has the potential for obtaining greater than 200 mJ/pulse. Previously, using a flash-lamp pumped Nd:YAG laser with round, top-hat profile, up to 24% IR-UV conversion efficiency was achieved with the same UV module. Efforts are underway to increase the IR-UV conversion efficiency of the all solid-state setup by modifying the pump laser spatial profile along with incorporating improved OPO crystals.

  16. Characterization of All Solid State Hydrogen Ion Selective Electrode Based on PVC-SR Hybrid Membranes

    Directory of Open Access Journals (Sweden)

    Yoon-Bo Shim

    2003-06-01

    Full Text Available Hydrogen ion selective membranes formulated with 3140 RTV silicone rubber (SR in PVC were studied to extend the life time of solid state ion sensors through improved membrane adhesion. All solid state hydrogen ion selective electrodes were prepared by incorporation of tridodecyl amine (TDDA as an ionophore, potassium tetrakis[3.5-bis(p-chlorophenylborate (KTpClPB as a lipophilic additive, bis(2-ethylhexyladipate (DOA as a plasticizer. Their linear dynamic range was pH 2.0-11.0 and showed the near Nernstian slope of 55.1±0.2 mV/pH (r=0.999. The ifluences from alkali and alkaline earth metal ions were studied for the response of the final ISE membrane composition. Impedance spectroscopic data showed that the resistance was increased by increasing SR content in PVC. Brewster Angle Microscopy (BAM image showed clear differences according to the SR compositions in PVC. Life time of the all solid state membrane electrode was extended to about 2 months by preparing the membrane with PVC and SR. The standard reference material from NIST (2181 HEPES Free acid and 2182 NaHEPESate was tested for the ISE and it gave good result.

  17. All Solid-State Lithium Metal Batteries Using Cross-linked Polymer Electrolytes

    Science.gov (United States)

    Pan, Qiwei; Li, Christopher; Soft Materials Team

    Nowadays, to prepare all solid-state lithium metal batteries with high rate capability and stability using solid polymer electrolytes (SPEs) is still a grand challenge because of the interfaces between the SPE and the electrodes. In this presentation, we report a series of hybrid SPEs with controlled network structures by using POSS as cross-linker. These hybrid network SPEs show promising ionic conductivity, mechanical properties, and lithium dendrite growth resistance. All solid-state LiFePO4/Li batteries were also prepared using these SPEs as the electrolytes to study the effect of conductivity and mechanical properties of the SPEs on the performance of the batteries. At 90 °C, the prepared cells show high rate capability and stability. Capacity up to 160 mAh/g can be obtained at a C/2 rate during the galvanostatic cycling. Capacity retention of the cells is higher than 80% after 250 cycles. Battery performance at 60 °C and decay mechanism of the batteries will also be discussed.

  18. Design and characterization of novel all-solid-state potentiometric sensor array dedicated to physiological measurements.

    Science.gov (United States)

    Toczyłowska-Mamińska, Renata; Kloch, Monika; Zawistowska-Deniziak, Anna; Bala, Agnieszka

    2016-10-01

    A novel construction of all-solid-state potentiometric sensor array designed for physiological measurements has been presented. The planar construction and elimination of liquid phase creates broad opportunities for the modifications in the sensing part of the sensor. The designed construction is based on all-solid-state ion-selective electrodes integrated with the ionic-liquid based reference electrode. Work parameters of the sensor arrays were characterized. It has been shown that presented sensor design indicates high sensitivity (55.2±1mV/dec, 56.3±2mV/dec, 58.4±1mV/dec and 53.5±1mV/pH for sodium-, potassium-, chloride- and pH-selective electrodes, respectively in 10(-5)-10(-1.5)M range of primary ions), low response time (t95 did not exceed 10s), high potential stability (potential drift in 28-h measurement was ca. ±2mV) and potential repeatability ca. ±1mV. The system was successfully applied to the simultaneous determination of K(+), Cl(-), Na(+) and pH in the model physiological solution and for the ion flux studies in human colon epithelium Caco-2 cell line as well.

  19. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    Science.gov (United States)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic -EO- based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm-1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  20. All-solid-state supercapacitors on silicon using graphene from silicon carbide

    Science.gov (United States)

    Wang, Bei; Ahmed, Mohsin; Wood, Barry; Iacopi, Francesca

    2016-05-01

    Carbon-based supercapacitors are lightweight devices with high energy storage performance, allowing for faster charge-discharge rates than batteries. Here, we present an example of all-solid-state supercapacitors on silicon for on-chip applications, paving the way towards energy supply systems embedded in miniaturized electronics with fast access and high safety of operation. We present a nickel-assisted graphitization method from epitaxial silicon carbide on a silicon substrate to demonstrate graphene as a binder-free electrode material for all-solid-state supercapacitors. We obtain graphene electrodes with a strongly enhanced surface area, assisted by the irregular intrusion of nickel into the carbide layer, delivering a typical double-layer capacitance behavior with a specific area capacitance of up to 174 μF cm-2 with about 88% capacitance retention over 10 000 cycles. The fabrication technique illustrated in this work provides a strategic approach to fabricate micro-scale energy storage devices compatible with silicon electronics and offering ultimate miniaturization capabilities.

  1. 1047-nm all-solid-state laser based on Nd: LuLF

    Institute of Scientific and Technical Information of China (English)

    Rui Li; Ting Yu; Lianhan Zhang; Weibiao Chen; Yin Hang

    2011-01-01

    @@ A compact all-solid-state continuous-wave (CW) laser at 1047 nm is developed based on Nd:LuLF, which is grown through the Czochralski technique. From the laser system, 1.3-W laser can be obtained, which corresponds to the slope efficiencies of 20.1% and 49.5% with respect to the incident and absorbed pump powers, respectively. To the best of our knowledge, this is the highest power level achieved at 1047 nm based on the Nd:LuLF crystal.%A compact all-solid-state continuous-wave (CW) laser at 1047 nm is developed based on Nd:LuLF, which is grown through the Czochralski technique. From the laser system, 1.3-W laser can be obtained, which corresponds to the slope efficiencies of 20.1% and 49.5% with respect to the incident and absorbed pump powers, respectively. To the best of our knowledge, this is the highest power level achieved at 1047 nm based on the Nd:LuLF crystal.

  2. All-solid state flexible supercapacitors based on graphene/polymer composites

    International Nuclear Information System (INIS)

    Recent advances in lightweight, flexible, and wearable electronic equipment has led to advancements in the development of sufficiently compact and flexible energy storage. A challenge remains to integrate the storage elements as closely as possible within a fully flexible device. Here, we demonstrate the fabrication of all-solid state flexible supercapacitors with the integration of two electrodes that consist of graphene/polymer composites. Robust conductive free-standing thin graphene/polymer composite electrodes were prepared through a simple “physical grinding” process. As-prepared composite electrodes store energy up to a reversible gravimetric capacitance of 90.6 F/g, at a constant current density of 0.5 A/g while also delivering long-term durability (90% retention) for excess of five-thousands of cycles. Notably, the enhancement of mechanical properties of supercapacitors enables them to maintain their electrochemical performance even when twisted or folded. This straightforward approach to the fabrication of fully flexible supercapacitors provides new design opportunities within wearable electronics and electrochemical applications. - Highlights: • All solid-sate supercapacitors were fabricated using graphene/polymer composite electrodes. • Supercapacitor devices show an excellent mechanical flexibility. • High electrochemical performances were demonstrated

  3. All-solid state flexible supercapacitors based on graphene/polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Won; Choi, Bong Gill, E-mail: bgchoi@kangwon.ac.kr

    2015-06-01

    Recent advances in lightweight, flexible, and wearable electronic equipment has led to advancements in the development of sufficiently compact and flexible energy storage. A challenge remains to integrate the storage elements as closely as possible within a fully flexible device. Here, we demonstrate the fabrication of all-solid state flexible supercapacitors with the integration of two electrodes that consist of graphene/polymer composites. Robust conductive free-standing thin graphene/polymer composite electrodes were prepared through a simple “physical grinding” process. As-prepared composite electrodes store energy up to a reversible gravimetric capacitance of 90.6 F/g, at a constant current density of 0.5 A/g while also delivering long-term durability (90% retention) for excess of five-thousands of cycles. Notably, the enhancement of mechanical properties of supercapacitors enables them to maintain their electrochemical performance even when twisted or folded. This straightforward approach to the fabrication of fully flexible supercapacitors provides new design opportunities within wearable electronics and electrochemical applications. - Highlights: • All solid-sate supercapacitors were fabricated using graphene/polymer composite electrodes. • Supercapacitor devices show an excellent mechanical flexibility. • High electrochemical performances were demonstrated.

  4. Modelling of photonic crystal fibres

    DEFF Research Database (Denmark)

    Knudsen, Erik

    2003-01-01

    In the presenta ph.d. work a theoretical study of aspects of modelling photonic crystal fibres was carried out. Photonic crystal fibres form a class of optical waveguides where guidance is no longer provided by a difference in refractive index between core and cladding. Instead, guidance is...... provided by an arrangement of air-holes running along the length of the fibre. Depending on the geometry of the fibre, the guiding mechanism may be either arising from the formation of a photonic bandgap in the cladding structure (photonic bandgap fibre), or by an effect resembling total internal...... modes in contiguous fibre segments curved at different radii. Overall microbend loss is expressed as a statistical mean of mismatch losses. Extending a well proven, established formula for macrobending losses in stop index fibres, we provide an estimate of macrobend losses in an air-guiding photonic...

  5. Quasi-two-dimensional optomechanical crystals with a complete phononic bandgap

    CERN Document Server

    Alegre, Thiago P Mayer; Winger, Martin; Painter, Oskar

    2010-01-01

    A fully planar two-dimensional optomechanical crystal formed in a silicon microchip is used to create a structure devoid of phonons in the GHz frequency range. A nanoscale photonic crystal cavity is placed inside the phononic bandgap crystal in order to probe the properties of the localized acoustic modes. By studying the trends in mechanical damping, mode density, and optomechanical coupling strength of the acoustic resonances over an array of structures with varying geometric properties, clear evidence of a complete phononic bandgap is shown.

  6. Design and Characterisation of Solid Electrolytes for All-Solid-State Lithium Batteries

    DEFF Research Database (Denmark)

    Sveinbjörnsson, Dadi Þorsteinn

    The development of all-solid-state lithium batteries, in which the currently used liquid electrolytes are substituted for solid electrolyte materials, could lead to safer batteries offering higher energy densities and longer cycle lifetimes. Designing suitable solid electrolytes with sufficient...... chemical and electrochemical stability, high lithium ion conduction and negligible electronic conduction remains a challenge. The highly lithium ion conducting LiBH4-LiI solid solution is a promising solid electrolyte material. Solid solutions with a LiI content of 6.25%-50% were synthesised by planetary......-rich microstructures during ball milling is found to significantly influence the conductivity of the samples. The long-range diffusion of lithium ions was measured using quasi-elastic neutron scattering. The solid solutions are found to exhibit two-dimensional conduction in the hexagonal plane of the crystal structure...

  7. High efficiency single frequency 355 nm all-solid-state UV laser

    Science.gov (United States)

    Xie, Xiaobing; Wei, Daikang; Ma, Xiuhua; Li, Shiguang; Liu, Jiqiao; Zhu, Xiaolei; Chen, Weibiao

    2016-05-01

    A novel conductively cooled high energy single-frequency 355 nm all-solid-state UV laser is presented based on sum-frequency mixing technique. In this system, a pulsed seeder laser at 1064 nm wavelength, modulated by an AOM, is directly amplified by the cascaded multi-stage hybrid laser amplifiers, and two LBO crystals are used for the SHG and SFG, finally a maximum UV pulse energy of 226 mJ at 355 nm wavelength is achieved with frequency-tripled conversion efficiency as high as 55%, the pulse width is around 12.2 ns at the repetition frequency of 30 Hz. The beam quality factor M 2 of the output UV laser is measured to be 2.54 and 2.98 respectively in two orthogonal directions.

  8. All-Solid-State Multi-wavelength Laser System from 208 to 830 nm

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shang-Hong; CHEN Guo-Fu; ZHAO Wei; WANG Yi-Shan; YU Lian-Jun

    2001-01-01

    Four-wavelength lasers from the near-infrared to deep-ultraviolet range, 532, 830, 415 and 208nm, have been developed in one all-solid-state laser system. The laser system is pumped by a diode-Q-YLF laser at 532nm,a Ti:sapphire laser, and the nonlinear second-harmonic-generation crystals LBO and BBO are used to generate different wavelengths. Maximum average powers (repetition rate 1 kHz) of 1.1 W at 830nm, 380m W at 415nm and 39mW at 208nm are obtained when the pumping power is 3.6 W. The main characteristics of this system are presented.

  9. Heterogeneous all-solid multicore fiber based multipath Michelson interferometer for high temperature sensing.

    Science.gov (United States)

    Duan, Li; Zhang, Peng; Tang, Ming; Wang, Ruoxu; Zhao, Zhiyong; Fu, Songnian; Gan, Lin; Zhu, Benpeng; Tong, Weijun; Liu, Deming; Shum, Perry Ping

    2016-09-01

    A compact high temperature sensor utilizing a multipath Michelson interferometer (MI) structure based on weak coupling multicore fiber (MCF) is proposed and experimentally demonstrated. The device is fabricated by program-controlled tapering the spliced region between single mode fiber (SMF) and a segment of MCF. After that, a spherical reflective structure is formed by arc-fusion splicing the end face of MCF. Theoretical analysis has been implemented for this specific multipath MI structure; beam propagation method based simulation and corresponding experiments were performed to investigate the effect of taper and spherical end face on system's performance. Benefiting from the multipath interferences and heterogeneous structure between the center core and surrounding cores of the all-solid MCF, an enhanced temperature sensitivity of 165 pm/°C up to 900°C and a high-quality interference spectrum with 25 dB fringe visibility were achieved. PMID:27607628

  10. An All Solid-State Pulsed Power Generator for Plasma Immersion Ion Implantation (PⅢ)

    Institute of Scientific and Technical Information of China (English)

    LIU Kefu; QIU Jian; WU Yifan

    2009-01-01

    An all solid-state pulsed power generator for plasma immersion ion implantation (PⅢ) is described. The pulsed power system is based on a Marx circuit configuration and semi-conductor switches, which have many advantages in adjustable repetition frequency, pulse width modulation and long serving life compared with the conventional circuit category, tube-based technologies such as gridded vacuum tubes, thyratrons, pulse forming networks and transformers.The operation of PⅢ with pulse repetition frequencies up to 500 Hz has been achieved at a pulse voltage amplitude from 2 kV to 60 kV, with an adjustable pulse duration from 1 μs to 100 μs.The proposed system and its performance, as used to drive a plasma ion implantation chamber,axe described in detail on the basis of the experimental results.

  11. The research on the micro-processing-used all-solid-state picosecond laser

    Science.gov (United States)

    Bai, Zhen-xu; Ai, Qing-kang; Duan, Jin-peng; Chen, Meng; Li, Gang

    2012-04-01

    A micro processing used LD end-pumped Nd:YVO4 all solid-state picosecond pulse laser was demonstrated under the semiconductor saturable absorption mirror(SESAM) mode-locking technology and regeneration amplifier technology, by using BBO crystal as electro-optic crystal and diode-side-pumped Nd:YAG. 1064nm laser was obtained with 1.47mJ single pulse energy, 15ps pulse width at 1 kHz repetition rate and the pulse energy fluctuation was less than 0.6% in 3 hours operation. Finally, through the galvanometric we got the beam focused, realizing the steel plate processing which thickness was 0.5mm and the aperture radius was 25.5μm.

  12. An all-solid-state laser source at 671 nm for cold atom experiments with lithium

    CERN Document Server

    Eismann, Ulrich; Canalias, Carlota; Zukauskas, Andrius; Trénec, Gérard; Vigué, Jacques; Chevy, Frédéric; Salomon, Christophe

    2011-01-01

    We present an all solid-state narrow line-width laser source emitting $670\\,\\mathrm{mW}$ output power at $671\\,\\mathrm{nm}$ delivered in a diffraction-limited beam. The source is based on a frequency-doubled diode-end-pumped ring laser operating on the ${^4F}_{3/2} \\rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled potassium titanyl phosphate (ppKTP) in an external build-up cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over $100\\,\\rm GHz$ is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally a simplified design based on intra-cavity doubling is described and first results are presented.

  13. Hollow-core photonic bandgap fiber sensor for detection of H2S concentration in natural gas%检测天然气中H2S气体浓度的光子带隙光纤传感器

    Institute of Scientific and Technical Information of China (English)

    郎文勇; 代冰; 唐东林

    2013-01-01

    Detection and monitoring of H2S are extremely important,since levels above 10 ppm are considered to be hazardous.Based on differential absorption,a kind of optical fiber gas sensor with high stability and sensitivity is proposed to detect H2S mixed in natural gas.This sensor is advantageous for eliminating the instability of light source and the impact of thermal zero drift and zero shift of photoelectric device.The gas sensing probe of the configuration uses four shorter pieces of hollow-core photonic bandgap fibers (HC-PBFs) with the same overall length instead of one long piece of HC-PBF to improve the system response.By analyzing the experimental data of different concentrations of H2S and CO2 absorption,the detection results of the prototype are as follows:the response time of sensor is 53 s,and the sensitivity is 2×10-6 mol/L.%为消除光源不稳定、光电器件的热零点漂移以及零点漂移对测量准确度的影响,基于差分吸收检测法,设计一种检测天然气中H2S气体浓度的高稳定性、高灵敏度的光子带隙传感器.为提高系统响应,采用4段串联的空芯光子晶体光纤(HC-PBF)作为气体传感探头.对不同组分浓度的H2S和CO2气体进行了检测,结果表明,系统响应时间为53 s,测量灵敏度可达2×10-6mol/L.

  14. Effective absorption coefficient for graded band-gap semiconductors and the expected photocurrent density in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Acevedo, Arturo [CINVESTAV del IPN, Electrical Engineering Department, Avenida IPN No. 2508, 07360 Mexico, D. F. (Mexico)

    2009-01-15

    A simple model for the generation of carriers by photons incident on a (linearly) decreasing band-gap material, such as has been described in recent CIGS solar cells, is developed. The model can be generalized for different cases such as increasing band-gap grading or for having a more complex band-gap profile. The model developed for direct band semiconductors such as CIGS or AlGaAs allows us to define an effective absorption coefficient, so that the ideal photocurrent density can be calculated in a similar manner as for solar cells with non-graded band-gap materials. We show that this model gives completely different results as those expected from intuitive approaches for calculating this ideal photocurrent density. We also show that grading of the band-gap of the absorbing material in solar cells makes the photocurrent less sensitive to the total band-gap change, in such a way that the design of the band-gap variation can be more flexible in order to have other advantages such as higher built-in voltage or higher back surface field in the device structure. (author)

  15. Magneto-tunable one-dimensional graphene-based photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jahani, D., E-mail: dariush110@gmail.com; Soltani-Vala, A., E-mail: asoltani@tabrizu.ac.ir; Barvestani, J.; Hajian, H. [Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2014-04-21

    We investigate the effect of a perpendicular static magnetic field on the optical bandgap of a one-dimensional (1D) graphene-dielectric photonic crystal in order to examine the possibility of reaching a rich tunable photonic bandgap. The solution of the wave equation in the presence of the anisotropic Hall situation suggests two decoupled circularly polarized wave each exhibiting different degrees of bandgap tunability. It is also numerically demonstrated that applying different values of field intensity lead to perceptible changes in photonic bandgap of such a structure. Finally, the effect of opening a finite electronic gap in the spectrum of graphene on the optical dispersion solution of such a 1D photonic crystal is reported. It is shown that increasing the value of the electronic gap results in the shrinkage of the associated photonic bandgaps.

  16. Photonic quasicrystals for application in WDM systems

    DEFF Research Database (Denmark)

    Romero-Vivas, J.; Chigrin, D. N.; Lavrinenko, Andrei;

    2005-01-01

    Photonic quasicrystals can possess an isotropic (complete) photonic bandgap even in the case of low refractive indices of the constitutive materials, which makes them atrractive optical materials with important technological applications. In this work, several aspects related to the design of wav...

  17. Photonic mesophases from cut rod rotators

    Energy Technology Data Exchange (ETDEWEB)

    Stelson, Angela C.; Liddell Watson, Chekesha M., E-mail: cml66@cornell.edu [Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Avendano, Carlos [Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2016-01-14

    The photonic band properties of random rotator mesophases are calculated using supercell methods applied to cut rods on a hexagonal lattice. Inspired by the thermodynamic mesophase for anisotropic building blocks, we vary the shape factor of cut fraction for the randomly oriented basis. We find large, stable bandgaps with high gap isotropy in the inverted and direct structures as a function of cut fraction, dielectric contrast, and filling fraction. Bandgap sizes up to 34.5% are maximized at high dielectric contrast for rods separated in a matrix. The bandgaps open at dielectric contrasts as low as 2.0 for the transverse magnetic polarization and 2.25 for the transverse electric polarization. Additionally, the type of scattering that promotes the bandgap is correlated with the effect of disorder on bandgap size. Slow light properties are investigated in waveguide geometry and slowdown factors up to 5 × 10{sup 4} are found.

  18. Monolayer MoS2 Bandgap Modulation by Dielectric Environments and Tunable Bandgap Transistors

    Science.gov (United States)

    Ryou, Junga; Kim, Yong-Sung; KC, Santosh; Cho, Kyeongjae

    2016-01-01

    Semiconductors with a moderate bandgap have enabled modern electronic device technology, and the current scaling trends down to nanometer scale have introduced two-dimensional (2D) semiconductors. The bandgap of a semiconductor has been an intrinsic property independent of the environments and determined fundamental semiconductor device characteristics. In contrast to bulk semiconductors, we demonstrate that an atomically thin two-dimensional semiconductor has a bandgap with strong dependence on dielectric environments. Specifically, monolayer MoS2 bandgap is shown to change from 2.8 eV to 1.9 eV by dielectric environment. Utilizing the bandgap modulation property, a tunable bandgap transistor, which can be in general made of a two-dimensional semiconductor, is proposed. PMID:27378032

  19. Monolayer MoS2 Bandgap Modulation by Dielectric Environments and Tunable Bandgap Transistors.

    Science.gov (United States)

    Ryou, Junga; Kim, Yong-Sung; Kc, Santosh; Cho, Kyeongjae

    2016-01-01

    Semiconductors with a moderate bandgap have enabled modern electronic device technology, and the current scaling trends down to nanometer scale have introduced two-dimensional (2D) semiconductors. The bandgap of a semiconductor has been an intrinsic property independent of the environments and determined fundamental semiconductor device characteristics. In contrast to bulk semiconductors, we demonstrate that an atomically thin two-dimensional semiconductor has a bandgap with strong dependence on dielectric environments. Specifically, monolayer MoS2 bandgap is shown to change from 2.8 eV to 1.9 eV by dielectric environment. Utilizing the bandgap modulation property, a tunable bandgap transistor, which can be in general made of a two-dimensional semiconductor, is proposed. PMID:27378032

  20. Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions

    Directory of Open Access Journals (Sweden)

    Hongwei Deng

    2010-11-01

    Full Text Available One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M, and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments.

  1. One-step spray processing of high power all-solid-state supercapacitors

    Science.gov (United States)

    Huang, Chun; Grant, Patrick S.

    2013-08-01

    Aqueous suspensions of multi-wall carbon nanotubes (MWNTs) in dilute H2SO4 were sprayed onto both sides of a Nafion membrane and dried to fabricate flexible solid-state supercapacitors. A single cell with MWNT-only electrodes had a capacitance of 57 F g-1 per electrode at 2 mV s-1 and 44 F g-1 at 150 mV s-1 but with low H+ mobility. Cells with MWNT + ionomer hybrid electrodes showed higher H+ mobility, and the electric double layer (EDL) capacitance increased to 145 F g-1 at 2 mV s-1 and 91 F g-1 at 150 mV s-1. The energy and power densities of one electrode charged to 1 V at 1 A g-1 were 12.9 Wh kg-1 and 3.3 kW kg-1 respectively. Three solid-state supercapacitor cells connected in series charged to 3 V at 1 and 2 A g-1 provided a device power density of 8.9 kW kg-1 at 1 A g-1 and 9.4 kW kg-1 at 2 A g-1, the highest for all-solid-state EDL supercapacitors.

  2. Diffusion and Interface Effects during Preparation of All-Solid Microstructured Fibers

    Directory of Open Access Journals (Sweden)

    Kobelke Jens

    2014-09-01

    Full Text Available All-solid microstructured optical fibers (MOF allow the realization of very flexible optical waveguide designs. They are prepared by stacking of doped silica rods or canes in complex arrangements. Typical dopants in silica matrices are germanium and phosphorus to increase the refractive index (RI, or boron and fluorine to decrease the RI. However, the direct interface contact of stacking elements often causes interrelated chemical reactions or evaporation during thermal processing. The obtained fiber structures after the final drawing step thus tend to deviate from the targeted structure risking degrading their favored optical functionality. Dopant profiles and design parameters (e.g., the RI homogeneity of the cladding are controlled by the combination of diffusion and equilibrium conditions of evaporation reactions. We show simulation results of diffusion and thermal dissociation in germanium and fluorine doped silica rod arrangements according to the monitored geometrical disturbances in stretched canes or drawn fibers. The paper indicates geometrical limits of dopant structures in sub-µm-level depending on the dopant concentration and the thermal conditions during the drawing process. The presented results thus enable an optimized planning of the preform parameters avoiding unwanted alterations in dopant concentration profiles or in design parameters encountered during the drawing process.

  3. Fabrication and performance of all-solid-state chloride sensors in synthetic concrete pore solutions.

    Science.gov (United States)

    Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

    2010-01-01

    One type of all-solid-state chloride sensor was fabricated using a MnO(2) electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K(+), Ca(2+), Na(+) and SO(4) (2-) ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. PMID:22163467

  4. All solid state lithium batteries based on lamellar garnet-type ceramic electrolytes

    Science.gov (United States)

    Du, Fuming; Zhao, Ning; Li, Yiqiu; Chen, Cheng; Liu, Ziwei; Guo, Xiangxin

    2015-12-01

    All solid-state lithium batteries are constructed by using highly conducting Ta-doped Li7La3Zr2O12 (LLZTO) as the solid electrolytes as well as the supports, coated with composite cathodes consisting of poly(vinylidene fluoride) (PVdF):LiTFSI, Ketjen Black, and carbon-coated LiFePO4 on one side and attached with Li anode on the other side. At 60 °C, the batteries show the first discharge capacity of 150 mAh g-1 at 0.05 C and 93% capacity retention after 100 cycles. As the current density increases from 0.05 C to 1 C, the specific capacity decreases from 150 mAh g-1 to 100 mAh g-1. Further elevated temperature up to 100 °C leads to further improved performance, i.e. 126 mAh g-1 at 1 C and 99% capacity retention after 100 cycles. This good performance can be attributed to the highly conducting ceramic electrolytes, the optimum electronic and ionic conducting networks in the composite cathodes, and closely contacted cathode/LLZTO interface. These results indicate that the present strategy is promising for development of high-performance solid-state Li-ion batteries operated at medium temperature.

  5. Highly flexible, all solid-state micro-supercapacitors from vertically aligned carbon nanotubes

    International Nuclear Information System (INIS)

    We report a highly flexible planar micro-supercapacitor with interdigitated finger electrodes of vertically aligned carbon nanotubes (VACNTs). The planar electrode structures are patterned on a thin polycarbonate substrate with a facile, maskless laser-assisted dry transfer method. Sputtered Ni is used to reduce the in-plane resistance of the VACNT electrodes. An ionogel, an ionic liquid in a semi-solid matrix, is used as an electrolyte to form a fully solid-state device. We measure a specific capacitance of 430 μF cm−2 for a scan rate of 0.1 V s−1 and achieve rectangular cyclic voltammograms at high scan rates of up to 100 V s−1. Minimal change in capacitance is observed under bending. Mechanical fatigue tests with more than 1000 cycles confirm the high flexibility and durability of the novel material combination chosen for this device. Our results indicate that this scalable and facile fabrication technique shows promise for application in integrated energy storage for all solid-state flexible microdevices. (paper)

  6. Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All-Solid-State Supercapacitors.

    Science.gov (United States)

    Hu, Xin; Shao, Wei; Hang, Xudong; Zhang, Xiaodong; Zhu, Wenguang; Xie, Yi

    2016-05-01

    As the properties of ultrathin two-dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next-generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu2 WS4 can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room-temperature electrical conductivity of hydrogenated-Cu2 WS4 nanosheet film was almost 10(10) times higher than that of pristine bulk sample with a value of about 2.9×10(4)  S m(-1) , which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated-Cu2 WS4 is robust and can be retained under high-temperature treatment. The fabricated all-solid-state flexible supercapacitor based on the hydrogenated-Cu2 WS4 nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm(-3) at a current density of 0.31 A cm(-3) . This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.

  7. Solid polymer electrolytes: materials designing and all-solid-state battery applications: an overview

    International Nuclear Information System (INIS)

    Polymer electrolytes are promising materials for electrochemical device applications, namely, high energy density rechargeable batteries, fuel cells, supercapacitors, electrochromic displays, etc. The area of polymer electrolytes has gone through various developmental stages, i.e. from dry solid polymer electrolyte (SPE) systems to plasticized, gels, rubbery to micro/nano-composite polymer electrolytes. The polymer gel electrolytes, incorporating organic solvents, exhibit room temperature conductivity as high as ∼10-3 S cm-1, while dry SPEs still suffer from poor ionic conductivity lower than 10-5 S cm-1. Several approaches have been adopted to enhance the room temperature conductivity in the vicinity of 10-4 S cm-1 as well as to improve the mechanical stability and interfacial activity of SPEs. In this review, the criteria of an ideal polymer electrolyte for electrochemical device applications have been discussed in brief along with presenting an overall glimpse of the progress made in polymer electrolyte materials designing, their broad classification and the recent advancements made in this branch of materials science. The characteristic advantages of employing polymer electrolyte membranes in all-solid-state battery applications have also been discussed. (topical review)

  8. Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All-Solid-State Supercapacitors.

    Science.gov (United States)

    Hu, Xin; Shao, Wei; Hang, Xudong; Zhang, Xiaodong; Zhu, Wenguang; Xie, Yi

    2016-05-01

    As the properties of ultrathin two-dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next-generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu2 WS4 can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room-temperature electrical conductivity of hydrogenated-Cu2 WS4 nanosheet film was almost 10(10) times higher than that of pristine bulk sample with a value of about 2.9×10(4)  S m(-1) , which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated-Cu2 WS4 is robust and can be retained under high-temperature treatment. The fabricated all-solid-state flexible supercapacitor based on the hydrogenated-Cu2 WS4 nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm(-3) at a current density of 0.31 A cm(-3) . This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes. PMID:27060363

  9. All-solid-state nitrate-selective electrode and its application in drinking water

    International Nuclear Information System (INIS)

    An all-solid-state nitrate-selective electrode with the implementation of graphene as the ion-to-electron transducer was reported. The charge-transfer process was examined by electrochemical impedance spectroscope and the hydrophobic nature of the graphene film was characterized via the potentiometric water layer test. The analytical performance of the nitrate-selective electrode was investigated by the determination of nitrate in drinking water. The obtained results showed that graphene can significantly facilitate the ion-to-electron transducer and prevent the formation of water layer between the ion-selective membrane and the graphene layer. The fabricated nitrate-selective electrode displayed a Nernstian slope of 57.9 mV per decade of nitrate concentration, a low detection limit of 3 × 10−5 M and a rapid response time (within 10 s) for concentration upon 10−4 M. The determination of real samples indicated that the constructed nitrate-selective electrode was capable of monitoring nitrate in drinking water, providing a handy alternative for routine analysis.

  10. Graphene Photonics and Optoelectronics

    OpenAIRE

    Bonaccorso, F.; Sun, Z.; Hasan, T.; Ferrari, A. C.

    2010-01-01

    The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential to be in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, ...

  11. Wide Bandgap Nanostructured Space Photovoltaics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Firefly, in collaboration with Rochester Institute of Technology, proposes an STTR program for the development of a wide-bandgap GaP-based space solar cell capable...

  12. Tuning the Bandgap of a Ternary Semiconductor

    OpenAIRE

    2005-01-01

    This interactive tutorial covers the following: The relationship between bandgap energy and the long wavelength cut-off of a detector response., The changes expected in long wavelength cut-off in response to changes in alloy composition and operating temperature.The interactions in this tutorial involve students using sliding scales to change the values of alloy composition, bandgap energy, cut-off wavelength, temperature, and intrinsic carrier concentration, and make observations of correspo...

  13. Porous-core honeycomb bandgap THz fiber

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Jepsen, Peter Uhd;

    2011-01-01

    In this Letter we propose a novel (to our knowledge) porous-core honeycomb bandgap design. The holes of the porous core are the same size as the holes in the surrounding cladding, thereby giving the proposed fiber important manufacturing benefits. The fiber is shown to have a 0:35-THz......-wide fundamental bandgap centered at 1:05 THz. The calculated minimum loss of the fiber is 0:25 dB=cm....

  14. Luminescence in Conjugated Molecular Materials under Sub-bandgap Excitation

    Energy Technology Data Exchange (ETDEWEB)

    So, Franky [University of Florida

    2014-05-08

    Light emission in semiconductors occurs when they are under optical and electrical excitation with energy larger than the bandgap energy. In some low-dimensional semiconductor heterostructure systems, this thermodynamic limit can be violated due to radiative Auger recombination (AR), a process in which the sub-bandgap energy released from a recombined electron-hole pair is transferred to a third particle leading to radiative band-to-band recombination.1 Thus far, photoluminescence up-conversion phenomenon has been observed in some low dimensional semiconductor systems, and the effect is very weak and it can only be observed at low temperatures. Recently, we discovered that efficient electroluminescence in poly[2-methoxy-5-(2’-ethylhexyloxy)-1, phenylenevinylene] (MEH-PPV) polymer light-emitting devices (PLEDs) at drive voltages below its bandgap voltage could be observed when a ZnO nanoparticles (NPs) electron injection layer was inserted between the polymer and the aluminum electrode. Specifically, emitted photons with energy of 2.13 eV can be detected at operating voltages as low as 1.2 V at room temperature. Based on these data, we propose that the sub-bandgap turn-on in the MEH-PPV device is due to an Auger-assisted energy up-conversion process. The significance of this discovery is three-fold. First, radiative recombination occurs at operating voltages below the thermodynamic bandgap voltage. This process can significantly reduce the device operating voltage. For example, the current density of the device with the ZnO NC layer is almost two orders of magnitude higher than that of the device without the NC layer. Second, a reactive metal is no longer needed for the cathode. Third, this electroluminescence up-conversion process can be applied to inorganic semiconductors systems as well and their operation voltages of inorganic LEDs can be reduced to about half of the bandgap energy. Based on our initial data, we propose that the sub-bandgap turn-on in MEH

  15. Colorful titanium oxides: a new class of photonic materials.

    Science.gov (United States)

    Li, Zhenzhen; Xin, Yanmei; Zhang, Zhonghai

    2015-12-21

    In this communication, a new class of photonic materials, namely, two-dimensional titanium oxide-based photonic crystals, are proposed and were fabricated with an electrochemical anodization method. The high structural periodicity of the nanostructures, and the feasible variability of the chemical compositions help to realize tunable photonic bandgaps for selective light absorption in broad wavelength regions.

  16. A miniature all-solid-state calcium electrode applied to in situ seawater measurement

    Science.gov (United States)

    Xu, Hui; Wang, You; Luo, Zhiyuan; Pan, Yiwen

    2013-12-01

    An all-solid-state miniature calcium ion selective electrode (ISE) based on poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT(PSS)) for continuous in situ measurement in seawater was studied. The electrode substrate was a platinum (Pt) wire of 0.5 mm diameter and PEDOT(PSS) was electropolymerized on one end of the Pt wire to act as the solid contact of this calcium ISE. The PEDOT(PSS) layer was covered with a calcium-selective poly(vinyl chloride) membrane, which contained ETH129 as calcium ionophore, potassium tetrakis-(p-chlorophenyl)borate as lipophilic anion and bis(2-ethylhexyl) sebacate as the plasticizer. Experiments using electrochemical impedance spectroscopy and reversed chronopotentiometry illustrated that electropolymerized PEDOT(PSS) decreased the resistance and improved the stability of the electrode. The sensors can work stably in the calcium ion concentration range of 10-6-10-1 mol L-1 with the slope of 27.7 mV/decade. Also Na+, K+ and Mg2+ can hardly interfere with the performance of the electrode. This electrode was applied to measure the calcium ion concentration of seawater samples. The experimental data showed that the electrode can resist the corrosion of seawater and its reproducibility was good (SD < 0.1 mM kg-1). The lifetime of such an electrode was at least six months. Because of the wire-shape and the small size of such a liquid junction free calcium electrode, it is pressure-resistant and easy to package and seal, therefore it is suitable for use in underwater equipment for in situ seawater measurement.

  17. All-Solid-State Iodide Selective Electrode for Iodimetry of Iodized Salts and Vitamin C

    Directory of Open Access Journals (Sweden)

    TIRUWORK MEQUANINT

    2012-12-01

    Full Text Available A laboratory-made all-solid state iodide selective electrode, with Ag2S-AgI coated on a graphite rod recovered from dry cell battery, was prepared according to previous procedures. The electrode’s linear response to iodide was in the concentration range of 10-6 M to 10-1 M with a slope of 56.85 mV/decade and a detection limit of 6×10-7M. Iodate recovery test for laboratory formulated iodate-iodized salt was found to be 98.6 % with a standard deviation of 1.14%. The titratability of the iodized salt solution was at least 10-200 ppm potassium iodate (6-120 ppm iodine, exhibiting distinct endpoints in the range wider than the ones set in regulatory standards and reflecting that QC monitoring in production and stability decline of iodine content upon storage can be performed with the electrode method. On the basis this potentiometric titration, the application of the laboratory-made iodide electrode (vs. a saturated calomel reference electrode was extended to the determination of iodine in commercial iodized salts. In all the iodine assays, the iodate-iodized salt was initially treated with acid and an excess of iodide before titration against Na2S2O3 solution. The iodine content in table salts iodized with iodide was determined by direct potentiometry. The electrode was further used for vitamin C (ascorbic acid determinations in pharmaceutical tablets and orange juice by back titrating excess I3- against standard Na2S2O3 in acidic media. The overall outcome is that the iodide ISE can be used as sharp endpoint indicator for these titrimetric reactions in place of the well known official, but visually monitored, starch- triodide end-point reaction detection.

  18. A Photonic Bandgap Filter Using Metallic Hilbert Curves

    Institute of Scientific and Technical Information of China (English)

    LI Hong-Qiang; WEI Ze-Yong; CHEN Hong; ZHANG Ye-Wen

    2005-01-01

    @@ We theoretically suggest that a metallic plate with Hilbert curves can possesses multiple resonances in a linear scale, leading to multiple stop bands and pass bands for electromagnetic waves over a wide frequency range.The forward transmission from a line source nearby a small plate covered by four cells with Hilbert curves is checked by a probe at the far field, the results agree well with the multiple resonance frequencies calculated by the plane wave incidence under a periodic boundary condition, the return loss spectra show that radiations of a line antenna working at 4.5 GHz can be greatly enhanced, which results from the interaction of the antenna and the subwavelength metallic plate. This kind of metallic pattern is very practical in multi-frequency functioned wave devices with sub-wavelength sizes.

  19. Photonic bandgap structures for long-range surface plasmon polaritons

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Boltasseva, Alexandra; Søndergaard, Thomas;

    2005-01-01

    Propagation of long-range surface plasmon polaritons (LR-SPPs) along periodically thickness-modulated metal stripes embedded in dielectric is studied both theoretically and experimentally for light wavelengths in the telecom range. We demonstrate that symmetric (with respect to the film surface) ...

  20. Hollow core photonic bandgap fibers for medical applications

    OpenAIRE

    Vural, Mert

    2009-01-01

    Ankara : The Department of Materials Science and Nanotechnology and the Institute of Engineering and Sciences of Bilkent University, 2009. Thesis (Master's) -- Bilkent University, 2009. Includes bibliographical references leaves 87-95. Vural, Mert Master's

  1. Analysis of photonic band-gap structures in stratified medium

    DEFF Research Database (Denmark)

    Tong, Ming-Sze; Yinchao, Chen; Lu, Yilong;

    2005-01-01

    in solving the Maxwell's equations numerically. It expands the temporal derivatives using the finite differences, while it adopts the Fourier transform (FT) properties to expand the spatial derivatives in Maxwell's equations. In addition, the method makes use of the chain-rule property in calculus together...... in electromagnetic and microwave applications once the Maxwell's equations are appropriately modeled. Originality/value - The method validates its values and properties through extensive studies on regular and defective 1D PBG structures in stratified medium, and it can be further extended to solving more...

  2. Tunable photonic bandgap fiber based devices for optical networks

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Scolari, Lara; Rottwitt, Karsten;

    2005-01-01

    In future all optical networks one of the enabling technologies is tunable elements including reconfigurable routers, switches etc. Thus, the development of a technology platform that allows construction of tuning components is critical. Lately, microstructured optical fibers, filled with liquid...... crystals, have proven to be a candidate for such a platform. Microstructured optical fibers offer unique wave-guiding properties that are strongly related to the design of the air holes in the cladding of the fiber. These wave-guiding properties may be altered by filling the air holes with a material, for...... example a liquid crystal that changes optical properties when subjected to, for example, an optical or an electrical field. The utilization of these two basic properties allows design of tunable optical devices for optical networks. In this work, we focus on applications of such devices and discuss recent...

  3. Petahertz optical drive with wide-bandgap semiconductor

    Science.gov (United States)

    Mashiko, Hiroki; Oguri, Katsuya; Yamaguchi, Tomohiko; Suda, Akira; Gotoh, Hideki

    2016-08-01

    High-speed photonic and electronic devices at present rely on radiofrequency electric fields to control the physical properties of a semiconductor, which limits their operating speed to terahertz frequencies (1012 Hz ref. ). Using the electric field from intense light pulses, however, could extend the operating frequency into the petahertz regime (1015 Hz ref. ). Here we demonstrate optical driving at a petahertz frequency in the wide-bandgap semiconductor gallium nitride. Few-cycle near-infrared pulses are shown to induce electric interband polarization though a multiphoton process. Dipole oscillations with a periodicity of 860 as are revealed in the gallium nitride electron and hole system by using the quantum interference between the two transitions from the valence and conduction band states, which are probed by an extremely short isolated attosecond pulse with a coherent broadband spectrum. In principle, this shows that the conductivity of the semiconductor can be manipulated on attosecond timescales, which corresponds to instantaneous light-induced switching from insulator to conductor. The resultant dipole frequency reaches 1.16 PHz, showing the potential for future high-speed signal processing technologies based on wide-bandgap semiconductors.

  4. Electronic structure characterization and bandgap engineeringofsolar hydrogen materials

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jinghua

    2007-11-01

    Bandgap, band edge positions as well as the overall band structure of semiconductors are of crucial importance in photoelectrochemical and photocatalytic applications. The energy position of the band edge level can be controlled by the electronegativity of the dopants, the pH of the solution (flatband potential variation of 60 mV per pH unit), as well as by quantum confinement effects. Accordingly, band edges and bandgap can be tailored to achieve specific electronic, optical or photocatalytic properties. Synchrotron radiation with photon energy at or below 1 keV is giving new insight into such areas as condensed matter physics and extreme ultraviolet optics technology. In the soft x-ray region, the question tends to be, what are the electrons doing as they migrated between the atoms. In this paper, I will present a number of soft x-ray spectroscopic study of nanostructured 3d metal compounds Fe{sub 2}O{sub 3} and ZnO.

  5. Effect of temperature on terahertz photonic and omnidirectional band gaps in one-dimensional quasi-periodic photonic crystals composed of semiconductor InSb.

    Science.gov (United States)

    Singh, Bipin K; Pandey, Praveen C

    2016-07-20

    Engineering of thermally tunable terahertz photonic and omnidirectional bandgaps has been demonstrated theoretically in one-dimensional quasi-periodic photonic crystals (PCs) containing semiconductor and dielectric materials. The considered quasi-periodic structures are taken in the form of Fibonacci, Thue-Morse, and double periodic sequences. We have shown that the photonic and omnidirectional bandgaps in the quasi-periodic structures with semiconductor constituents are strongly depend on the temperature, thickness of the constituted semiconductor and dielectric material layers, and generations of the quasi-periodic sequences. It has been found that the number of photonic bandgaps increases with layer thickness and generation of the quasi-periodic sequences. Omnidirectional bandgaps in the structures have also been obtained. Results show that the bandwidths of photonic and omnidirectional bandgaps are tunable by changing the temperature and lattice parameters of the structures. The generation of quasi-periodic sequences can also change the properties of photonic and omnidirectional bandgaps remarkably. The frequency range of the photonic and omnidirectional bandgaps can be tuned by the change of temperature and layer thickness of the considered quasi-periodic structures. This work will be useful to design tunable terahertz PC devices. PMID:27463924

  6. Anisotropic nanostructures directly written by fs pulses in wide-bandgap materials

    OpenAIRE

    Baumberg, J. J.; Mills, J. D.; Kazansky, P. G.; Bricchi, E.

    2003-01-01

    The use of lasers to directly pattern optoelectronic devices primarily utilizes direct irradiation by UV light. We present here an alternative route using multi-photon absorption within a spherical focus in 3D space, thus allowing complex embedded structures to be directly written. In wide-bandgap materials such as chalcogenide, fluoride and silica glasses, our observations suggest free electrons are produced within the focus of a high-power infrared ultrashort pulse. The anisotropic interact...

  7. MUTUAL COUPLING REDUCTION BETWEEN MICROSTRIP ANTENNAS USING ELECTROMAGNETIC BANDGAP STRUCTURE

    Directory of Open Access Journals (Sweden)

    G.N. Gaikwad

    2011-03-01

    Full Text Available When the number of antenna elements is placed in forming the arrays, mutual coupling between the antenna elements is a critical issue. This is particularly concern in phase array antennas. Mutual coupling is a potential source of performance degradation in the form of deviation of the radiation pattern from the desired one, gain reduction due to excitation of surface wave, increased side lobe levels etc. EBG (Electromagnetic Band Gap structure (also called as Photonic Bandgap Structure PBG not only enhances the performance of the patch antennas but also provides greater amount of isolation when placed between the microstrip arrays. This greatly reduces the mutual coupling between the antenna elements. The radiation efficiency, gain, antenna efficiency, VSWR, frequency, directivity etc greatly improves over the conventional patch antennas using EBG. The EBG structure and normal patch antenna is simulated using IE3D antenna simulation software.

  8. Mid-Infrared nonlinear silicon photonics

    OpenAIRE

    Liu, Xiaoping; Kuyken, Bart; Green, William M. J.; Osgood, Richard M.; Baets, Roel; Roelkens, Günther

    2014-01-01

    Recently there has been a growing interest in mid-infrared (mid-IR) photonic technology with a wavelength of operation approximately from 2-14 mu m. Among several established mid-IR photonic platforms, silicon nanophotonic platform could potentially offer ultra-compact, and monolithically integrated mid-IR photonic devices and device arrays, which could have board impact in the mid-IR technology, such as molecular spectroscopy, and imaging. At room temperature, silicon has a bandgap similar t...

  9. Quasi-Fermi level splitting and sub-bandgap absorptivity from semiconductor photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Katahara, John K.; Hillhouse, Hugh W., E-mail: h2@uw.edu [Department of Chemical Engineering, University of Washington, Seattle, Washington 98105 (United States)

    2014-11-07

    A unified model for the direct gap absorption coefficient (band-edge and sub-bandgap) is developed that encompasses the functional forms of the Urbach, Thomas-Fermi, screened Thomas-Fermi, and Franz-Keldysh models of sub-bandgap absorption as specific cases. We combine this model of absorption with an occupation-corrected non-equilibrium Planck law for the spontaneous emission of photons to yield a model of photoluminescence (PL) with broad applicability to band-band photoluminescence from intrinsic, heavily doped, and strongly compensated semiconductors. The utility of the model is that it is amenable to full-spectrum fitting of absolute intensity PL data and yields: (1) the quasi-Fermi level splitting, (2) the local lattice temperature, (3) the direct bandgap, (4) the functional form of the sub-bandgap absorption, and (5) the energy broadening parameter (Urbach energy, magnitude of potential fluctuations, etc.). The accuracy of the model is demonstrated by fitting the room temperature PL spectrum of GaAs. It is then applied to Cu(In,Ga)(S,Se){sub 2} (CIGSSe) and Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) to reveal the nature of their tail states. For GaAs, the model fit is excellent, and fitted parameters match literature values for the bandgap (1.42 eV), functional form of the sub-bandgap states (purely Urbach in nature), and energy broadening parameter (Urbach energy of 9.4 meV). For CIGSSe and CZTSSe, the model fits yield quasi-Fermi leveling splittings that match well with the open circuit voltages measured on devices made from the same materials and bandgaps that match well with those extracted from EQE measurements on the devices. The power of the exponential decay of the absorption coefficient into the bandgap is found to be in the range of 1.2 to 1.6, suggesting that tunneling in the presence of local electrostatic potential fluctuations is a dominant factor contributing to the sub-bandgap absorption by either purely electrostatic (screened Thomas-Fermi) or

  10. Using Protection Layers for a 2-Photon Water Splitting Device

    DEFF Research Database (Denmark)

    Seger, Brian; Mei, Bastian Timo; Frydendal, Rasmus;

    2015-01-01

    optimized to absorb low energy photons (small bandgap). To a large degree this approach has been hindered by corrosion issues. In this talk I will first discuss how our computational screening of 2,400 materials showed that very few materials can efficiently absorb light without corroding in water splitting......The 2-photon tandem device for photocatalytic water splitting has been theoretically shown to provide a higher efficiency than a single photon device(1). This increased efficiency can be achieved by having one material optimized to absorb high energy photons (large bandgap) and another material...

  11. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging

    NARCIS (Netherlands)

    Zhao, Q.; Schelen, B.; Schouten, R., et al.

    2012-01-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device des

  12. Manufacturing method of photonic crystal

    Science.gov (United States)

    Park, In Sung; Lee, Tae Ho; Ahn, Jin Ho; Biswas, Rana; Constant, Kristen P.; Ho, Kai-Ming; Lee, Jae-Hwang

    2013-01-29

    A manufacturing method of a photonic crystal is provided. In the method, a high-refractive-index material is conformally deposited on an exposed portion of a periodic template composed of a low-refractive-index material by an atomic layer deposition process so that a difference in refractive indices or dielectric constants between the template and adjacent air becomes greater, which makes it possible to form a three-dimensional photonic crystal having a superior photonic bandgap. Herein, the three-dimensional structure may be prepared by a layer-by-layer method.

  13. Defect solitons in photonic lattices.

    Science.gov (United States)

    Yang, Jianke; Chen, Zhigang

    2006-02-01

    Nonlinear defect modes (defect solitons) and their stability in one-dimensional photonic lattices with focusing saturable nonlinearity are investigated. It is shown that defect solitons bifurcate out from every infinitesimal linear defect mode. Low-power defect solitons are linearly stable in lower bandgaps but unstable in higher bandgaps. At higher powers, defect solitons become unstable in attractive defects, but can remain stable in repulsive defects. Furthermore, for high-power solitons in attractive defects, we found a type of Vakhitov-Kolokolov (VK) instability which is different from the usual VK instability based on the sign of the slope in the power curve. Lastly, we demonstrate that in each bandgap, in addition to defect solitons which bifurcate from linear defect modes, there is also an infinite family of other defect solitons which can be stable in certain parameter regimes. PMID:16605473

  14. A quantum photonic dissipative transport theory

    Science.gov (United States)

    Lei, Chan U.; Zhang, Wei-Min

    2012-05-01

    In this paper, a quantum transport theory for describing photonic dissipative transport dynamics in nanophotonics is developed. The nanophotonic devices concerned in this paper consist of on-chip all-optical integrated circuits incorporating photonic bandgap waveguides and driven resonators embedded in nanostructured photonic crystals. The photonic transport through waveguides is entirely determined from the exact master equation of the driven resonators, which is obtained by explicitly eliminating all the degrees of freedom of the waveguides (treated as reservoirs). Back-reactions from the reservoirs are fully taken into account. The relation between the driven photonic dynamics and photocurrents is obtained explicitly. The non-Markovian memory structure and quantum decoherence dynamics in photonic transport can then be fully addressed. As an illustration, the theory is utilized to study the transport dynamics of a photonic transistor consisting of a nanocavity coupled to two waveguides in photonic crystals. The controllability of photonic transport through the external driven field is demonstrated.

  15. Ultra-wide bandwidth wavelength selective couplers based on the all solid multi-core Ge-doped fibre

    Science.gov (United States)

    Li, X.; Sun, B.; Yu, Y.

    2014-09-01

    A novel wavelength selective coupler based on the all solid nine-core Ge-doped fibre has been proposed. The wavelength selective coupler is based on the phenomenon of a multi-core coupling. All the cores are made of Ge-doped silica and the index of central core is larger than the outer core. At the fixed fibre length, the different wavelength can be selected. The performances of coupling and propagation characteristics have been numerically investigated by using a full beam propagation method (BPM). Simulation results show that the all solid nine-core Ge-doped fibre can achieve simultaneous shorter coupler length and wideband filtering characteristics. The 0.763 mm and 0.745 mm wavelength selective coupler are proposed to achieve different wavelength division and the bandwidth is up to the 400 nm, and 300 nm, respectively.

  16. Radiation risk models for all solid cancers other than those types of cancer requiring individual assessments after a nuclear accident.

    Science.gov (United States)

    Walsh, Linda; Zhang, Wei

    2016-03-01

    In the assessment of health risks after nuclear accidents, some health consequences require special attention. For example, in their 2013 report on health risk assessment after the Fukushima nuclear accident, the World Health Organisation (WHO) panel of experts considered risks of breast cancer, thyroid cancer and leukaemia. For these specific cancer types, use was made of already published excess relative risk (ERR) and excess absolute risk (EAR) models for radiation-related cancer incidence fitted to the epidemiological data from the Japanese A-bomb Life Span Study (LSS). However, it was also considered important to assess all other types of solid cancer together and the WHO, in their above-mentioned report, stated "No model to calculate the risk for all other solid cancer excluding breast and thyroid cancer risks is available from the LSS data". Applying the LSS models for all solid cancers along with the models for the specific sites means that some cancers have an overlap in the risk evaluations. Thus, calculating the total solid cancer risk plus the breast cancer risk plus the thyroid cancer risk can overestimate the total risk by several per cent. Therefore, the purpose of this paper was to publish the required models for all other solid cancers, i.e. all solid cancers other than those types of cancer requiring special attention after a nuclear accident. The new models presented here have been fitted to the same LSS data set from which the risks provided by the WHO were derived. Although it is known already that the EAR and ERR effect modifications by sex are statistically significant for the outcome "all solid cancer", it is shown here that sex modification is not statistically significant for the outcome "all solid cancer other than thyroid and breast cancer". It is also shown here that the sex-averaged solid cancer risks with and without the sex modification are very similar once breast and thyroid cancers are factored out. Some other notable model

  17. Radiation risk models for all solid cancers other than those types of cancer requiring individual assessments after a nuclear accident.

    Science.gov (United States)

    Walsh, Linda; Zhang, Wei

    2016-03-01

    In the assessment of health risks after nuclear accidents, some health consequences require special attention. For example, in their 2013 report on health risk assessment after the Fukushima nuclear accident, the World Health Organisation (WHO) panel of experts considered risks of breast cancer, thyroid cancer and leukaemia. For these specific cancer types, use was made of already published excess relative risk (ERR) and excess absolute risk (EAR) models for radiation-related cancer incidence fitted to the epidemiological data from the Japanese A-bomb Life Span Study (LSS). However, it was also considered important to assess all other types of solid cancer together and the WHO, in their above-mentioned report, stated "No model to calculate the risk for all other solid cancer excluding breast and thyroid cancer risks is available from the LSS data". Applying the LSS models for all solid cancers along with the models for the specific sites means that some cancers have an overlap in the risk evaluations. Thus, calculating the total solid cancer risk plus the breast cancer risk plus the thyroid cancer risk can overestimate the total risk by several per cent. Therefore, the purpose of this paper was to publish the required models for all other solid cancers, i.e. all solid cancers other than those types of cancer requiring special attention after a nuclear accident. The new models presented here have been fitted to the same LSS data set from which the risks provided by the WHO were derived. Although it is known already that the EAR and ERR effect modifications by sex are statistically significant for the outcome "all solid cancer", it is shown here that sex modification is not statistically significant for the outcome "all solid cancer other than thyroid and breast cancer". It is also shown here that the sex-averaged solid cancer risks with and without the sex modification are very similar once breast and thyroid cancers are factored out. Some other notable model

  18. Simultaneous Band-Gap Narrowing and Carrier-Lifetime Prolongation of Organic-Inorganic Trihalide Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingping; Liu, Gang; Gong, Jue; Hu, Qingyang; Schaller, Richard D.; Dera, Przemyslaw; Zhang, Dongzhou; Liu, Zhenxian; Yang, Wenge; Zhu, Kai; Tang, Yuzhao; Wang, Chuanyi; Wei, Su-Huai; Xu, Tao; Mao, Ho-kwang

    2016-08-09

    The organic-inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic materials. As regulated by Shockley-Queisser theory, a formidable materials science challenge for improvement to the next level requires further band-gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band-gap photovoltage. Herein, by applying controllable hydrostatic pressure, we have achieved unprecedented simultaneous enhancement in both band-gap narrowing and carrier-lifetime prolongation (up to 70% to -100% increase) under mild pressures at -0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon-electron interaction and maps a pioneering route toward a further increase in their photovoltaic performance.

  19. Simultaneous band-gap narrowing and carrier-lifetime prolongation of organic-inorganic trihalide perovskites.

    Science.gov (United States)

    Kong, Lingping; Liu, Gang; Gong, Jue; Hu, Qingyang; Schaller, Richard D; Dera, Przemyslaw; Zhang, Dongzhou; Liu, Zhenxian; Yang, Wenge; Zhu, Kai; Tang, Yuzhao; Wang, Chuanyi; Wei, Su-Huai; Xu, Tao; Mao, Ho-Kwang

    2016-08-01

    The organic-inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic materials. As regulated by Shockley-Queisser theory, a formidable materials science challenge for improvement to the next level requires further band-gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band-gap photovoltage. Herein, by applying controllable hydrostatic pressure, we have achieved unprecedented simultaneous enhancement in both band-gap narrowing and carrier-lifetime prolongation (up to 70% to ∼100% increase) under mild pressures at ∼0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon-electron interaction and maps a pioneering route toward a further increase in their photovoltaic performance. PMID:27444014

  20. Three-dimensional photonic crystals created by single-step multi-directional plasma etching.

    Science.gov (United States)

    Suzuki, Katsuyoshi; Kitano, Keisuke; Ishizaki, Kenji; Noda, Susumu

    2014-07-14

    We fabricate 3D photonic nanostructures by simultaneous multi-directional plasma etching. This simple and flexible method is enabled by controlling the ion-sheath in reactive-ion-etching equipment. We realize 3D photonic crystals on single-crystalline silicon wafers and show high reflectance (>95%) and low transmittance (communication wavelengths, suggesting the formation of a complete photonic bandgap. Moreover, our method simply demonstrates Si-based 3D photonic crystals that show the photonic bandgap effect in a shorter wavelength range around 0.6 μm, where further fine structures are required.

  1. Phonon wave interference and thermal bandgap materials.

    Science.gov (United States)

    Maldovan, Martin

    2015-07-01

    Wave interference modifies phonon velocities and density of states, and in doing so creates forbidden energy bandgaps for thermal phonons. Materials that exhibit wave interference effects allow the flow of thermal energy to be manipulated by controlling the material's thermal conductivity or using heat mirrors to reflect thermal vibrations. The technological potential of these materials, such as enhanced thermoelectric energy conversion and improved thermal insulation, has fuelled the search for highly efficient phonon wave interference and thermal bandgap materials. In this Progress Article, we discuss recent developments in the understanding and manipulation of heat transport. We show that the rational design and fabrication of nanostructures provides unprecedented opportunities for creating wave-like behaviour of heat, leading to a fundamentally new approach for manipulating the transfer of thermal energy.

  2. Wide bandgap matrix switcher, amplifier and oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Sampayan, Stephen

    2016-08-16

    An electronic device comprising an optical gate, an electrical input an electrical output and a wide bandgap material positioned between the electrical input and the electrical output to control an amount of current flowing between the electrical input and the electrical output in response to a stimulus received at the optical gate can be used in wideband telecommunication applications in transmission of multi-channel signals.

  3. Photonics based on carbon nanotubes

    OpenAIRE

    Gu, Qingyuan; Gicquel-Guézo, Maud; Loualiche, Slimane; Pouliquen, Julie Le; Batte, Thomas; Folliot, Hervé; Dehaese, Olivier; Grillot, Frederic; Battie, Yann; Loiseau, Annick; Liang, Baolai; Huffaker, Diana

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the effi...

  4. Two-dimensional heterogeneous photonic bandedge laser

    OpenAIRE

    Kwon, Soon-Hong; Kim, Se-Heon; Kim, Sun-Kyung; Lee, Yong-Hee; Kim, Sung-Bock

    2004-01-01

    We proposed and realized a two-dimensional (2D) photonic bandedge laser surrounded by the photonic bandgap. The heterogeneous photonic crystal structure consists of two triangular lattices of the same lattice constant with different air hole radii. The photonic crystal laser was realized by room-temperature optical pumping of air-bridge slabs of InGaAsP quantum wells emitting at 1.55 micrometer. The lasing mode was identified from its spectral positions and polarization directions. A low thre...

  5. Engineering photonic density of states using metamaterials

    DEFF Research Database (Denmark)

    Jacob, Z.; Kim, J.Y.; Naik, G.V.;

    2010-01-01

    The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a...... such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering....

  6. Silicon nanostructures for photonics and photovoltaics

    NARCIS (Netherlands)

    F. Priolo; T. Gregorkiewicz; M. Galli; T.F. Krauss

    2014-01-01

    Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanosc

  7. Ab initio study of the bandgap engineering of Al1−xGaxN for optoelectronic applications

    KAUST Repository

    Amin, B.

    2011-01-19

    A theoretical study of Al1−xGaxN, based on the full-potential linearized augmented plane wave method, is used to investigate the variations in the bandgap,optical properties, and nonlinear behavior of the compound with the change in the Ga concentration. It is found that the bandgap decreases with the increase in Ga. A maximum value of 5.50 eV is determined for the bandgap of pure AlN, which reaches a minimum value of 3.0 eV when Al is completely replaced by Ga. The static index of refraction and dielectric constant decreases with the increase in the bandgap of the material, assigning a high index of refraction to pure GaN when compared to pure AlN. The refractive index drops below 1 for higher energy photons, larger than 14 eV. The group velocity of these photons is larger than the vacuum velocity of light. This astonishing result shows that at higher energies the optical properties of the material shifts from linear to nonlinear. Furthermore, frequency dependent reflectivity and absorption coefficients show that peak values of the absorption coefficient and reflectivity shift toward lower energy in the ultraviolet (UV) spectrum with the increase in Ga concentration. This comprehensive theoretical study of the optoelectronic properties predicts that the material can be effectively used in the optical devices working in the visible and UV spectrum.

  8. Coherent mid-infrared supercontinuum generation in all-solid chalcogenide microstructured fibers with all-normal dispersion.

    Science.gov (United States)

    Liu, Lai; Cheng, Tonglei; Nagasaka, Kenshiro; Tong, Hoangtuan; Qin, Guanshi; Suzuki, Takenobu; Ohishi, Yasutake

    2016-01-15

    We report the coherent mid-infrared supercontinuum generation in an all-solid chalcogenide microstructured fiber with all-normal dispersion. The chalcogenide microstructured fiber is a four-hole structure with core material of AsSe2 and air holes that are replaced by As2S5 glass rods. Coherent mid-infrared supercontinuum light extended to 3.3 μm is generated in a 2 cm long chalcogenide microstructured fiber pumped by a 2.7 μm laser. PMID:26766722

  9. Investigations of a high power all-solid-state synchronously-pumped lithium triborate optical parametric oscillator

    OpenAIRE

    Butterworth, Stuart David

    1997-01-01

    The work presented in this thesis describes the operation of a high power all-solid-state synchronously pumped optical parametric oscillator based on a Brewster-angled lithium triborate crystal. The OPO is pumped by a resonant frequency doubled, amplified, diode-pumped mode-locked laser. Performance characteristics of the individual "modules" in the overall system are presented. The work describes the production of 2.0 psec pulses from a diode-pumped Nd:YLF laser using the passive mode-lo...

  10. All-Solid-State Textile Batteries Made from Nano-Emulsion Conducting Polymer Inks for Wearable Electronics

    OpenAIRE

    Tapani Ryhänen; Darryl Cotton; Di Wei

    2012-01-01

    A rollable and all-solid-state textile lithium battery based on fabric matrix and polymer electrolyte that allows flexibility and fast-charging capability is reported. When immerged into poly(3,4-ethylenedioxythiophene) (PEDOT) nano-emulsion inks, an insulating fabric is converted into a conductive battery electrode for a fully solid state lithium battery with the highest specific energy capacity of 68 mAh/g. This is superior to most of the solid-state conducting polymer primary and/or second...

  11. Regrowth-Free Processing for GaAs and InP Photonic Integrated Circuits

    Institute of Scientific and Technical Information of China (English)

    John; H.; Marsh

    2003-01-01

    Technologies are described for integrating multiple bandgaps and photonic crystal structures monolithically in a semiconductor chip. Practical devices examples include high power 980 nm pumps, 2×2 crosspoint switches and lasers modelocked at THz frequencies.

  12. High-performance flexible all-solid-state microbatteries based on solid electrolyte of lithium boron oxynitride

    Science.gov (United States)

    Song, Seung-Wan; Lee, Ki-Chang; Park, Ho-Young

    2016-10-01

    Rapidly growing interest and demand for wearable electronics require the development of flexible and lightweight all-solid-state batteries as power sources that guarantee high performance and safety with the absence of the risk of fire or explosion that can occur with traditional liquid electrolyte systems. Herein, we successfully fabricate new flexible all-solid-state microbatteries integrating a solid electrolyte film of lithium boron oxynitride (LiBON) on a flexible substrate using sophisticated thin-film fabrication technology. The new microbattery of Li/LiBON/LiCoO2 exhibits excellent mechanical integrity even under severe bending and twisting test conditions, enabling the realization of flexible microbatteries. The microbatteries demonstrate superior electrochemical cycling stability relative to conventional batteries, delivering an outstanding capacity retention of 90% on the 1000th cycle. Furthermore, operation at various temperatures from -10 °C to +60 °C and fast charging within 3-6 min are achieved. With various types of flexible substrates, the microbatteries can provide diverse opportunities for flexible and wearable electronics.

  13. Atomic layer deposition of lithium phosphates as solid-state electrolytes for all-solid-state microbatteries

    International Nuclear Information System (INIS)

    Atomic layer deposition (ALD) has been shown as a powerful technique to build three-dimensional (3D) all-solid-state microbattery, because of its unique advantages in fabricating uniform and pinhole-free thin films in 3D structures. The development of solid-state electrolyte by ALD is a crucial step to achieve the fabrication of 3D all-solid-state microbattery by ALD. In this work, lithium phosphate solid-state electrolytes were grown by ALD at four different temperatures (250, 275, 300, and 325 °C) using two precursors (lithium tert-butoxide and trimethylphosphate). A linear dependence of film thickness on ALD cycle number was observed and uniform growth was achieved at all four temperatures. The growth rate was 0.57, 0.66, 0.69, and 0.72 Å/cycle at deposition temperatures of 250, 275, 300, and 325 °C, respectively. Furthermore, x-ray photoelectron spectroscopy confirmed the compositions and chemical structures of lithium phosphates deposited by ALD. Moreover, the lithium phosphate thin films deposited at 300 °C presented the highest ionic conductivity of 1.73 × 10−8 S cm−1 at 323 K with ∼0.51 eV activation energy based on the electrochemical impedance spectroscopy. The ionic conductivity was calculated to be 3.3 × 10−8 S cm−1 at 26 °C (299 K). (paper)

  14. High-energy all-solid-state sodium beacon laser with line width of 0.6 GHz

    Science.gov (United States)

    Lu, Yan-Hua; Xie, Gang; Zhang, Lei; Fan, Guo-Bin; Pang, Yu; Li, Nan; Wei, Bin; Gao, Song-Xin; Zhang, Wei; Tang, Chun

    2015-02-01

    A high-energy all-solid-state sodium beacon laser at 589 nm with a repetition rate of 50 Hz is introduced, which is based on sum frequency mixing between a 1,064 nm laser and a 1,319 nm laser. The 1,064 nm laser, which features an external modulated CW seed laser and several stages of amplifiers, can provide pulse energy of 740 mJ with ultra-narrow line width (~17 kHz) and superior stability. The 1,319 nm laser can deliver pulse energy of 580 mJ with a narrow line width of 0.6 GHz. By sum frequency mixing in a LBO crystal, pulse energy of 380 mJ is achieved at 589 nm with a conversion efficiency of 29 %. By controlling the center wavelength of 1,064 nm laser, the target beam's central wavelength is locked to be 589.1592 nm with a line width of 0.6 GHz, which is dominated mainly by the 1,319 nm laser. The beam quality factor is measured to be M 2 = 1.6. The pulse duration is measured to be 140 μs in full-width at half-maximum (FWHM). To the best of our knowledge, this represents the highest pulse energy for all-solid-state sodium beacon laser ever reported.

  15. Colorful titanium oxides: a new class of photonic materials

    Science.gov (United States)

    Li, Zhenzhen; Xin, Yanmei; Zhang, Zhonghai

    2015-11-01

    In this communication, a new class of photonic materials, namely, two-dimensional titanium oxide-based photonic crystals, are proposed and were fabricated with an electrochemical anodization method. The high structural periodicity of the nanostructures, and the feasible variability of the chemical compositions help to realize tunable photonic bandgaps for selective light absorption in broad wavelength regions.In this communication, a new class of photonic materials, namely, two-dimensional titanium oxide-based photonic crystals, are proposed and were fabricated with an electrochemical anodization method. The high structural periodicity of the nanostructures, and the feasible variability of the chemical compositions help to realize tunable photonic bandgaps for selective light absorption in broad wavelength regions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05374a

  16. Research on micro-sized acoustic bandgap structures.

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, James Grant; McCormick, Frederick Bossert; Su, Mehmet F.; El-Kady, Ihab Fathy; Olsson, Roy H., III; Tuck, Melanie R.

    2010-01-01

    Phononic crystals (or acoustic crystals) are the acoustic wave analogue of photonic crystals. Here a periodic array of scattering inclusions located in a homogeneous host material forbids certain ranges of acoustic frequencies from existence within the crystal, thus creating what are known as acoustic (or phononic) bandgaps. The vast majority of phononic crystal devices reported prior to this LDRD were constructed by hand assembling scattering inclusions in a lossy viscoelastic medium, predominantly air, water or epoxy, resulting in large structures limited to frequencies below 1 MHz. Under this LDRD, phononic crystals and devices were scaled to very (VHF: 30-300 MHz) and ultra (UHF: 300-3000 MHz) high frequencies utilizing finite difference time domain (FDTD) modeling, microfabrication and micromachining technologies. This LDRD developed key breakthroughs in the areas of micro-phononic crystals including physical origins of phononic crystals, advanced FDTD modeling and design techniques, material considerations, microfabrication processes, characterization methods and device structures. Micro-phononic crystal devices realized in low-loss solid materials were emphasized in this work due to their potential applications in radio frequency communications and acoustic imaging for medical ultrasound and nondestructive testing. The results of the advanced modeling, fabrication and integrated transducer designs were that this LDRD produced the 1st measured phononic crystals and phononic crystal devices (waveguides) operating in the VHF (67 MHz) and UHF (937 MHz) frequency bands and established Sandia as a world leader in the area of micro-phononic crystals.

  17. Photonic band structure of two-dimensional metal/dielectric photonic crystals

    International Nuclear Information System (INIS)

    An improved plane wave expansion method for the numerical calculation of photonic bands of metal/dielectric photonic crystal (PC) are presented. This method is applied to two-dimensional PCs with frequency-dependent dielectric constants. We obtained the photonic band structure of three kinds of structures: sawtooth, cylinder and hole PCs. The results show that the lowest band-1 is relatively flat, and does not approach zero. Also, there is no complete band-gap that extends throughout the first Brillouin zone for these three structures. However, there are partial band-gaps in different directions in the first Brillouin zone. For the complementary cylinder and hole PCs, their photonic bands are similar except for the lowest three bands; the hole PC’s lowest frequency of band-1 is larger than that of cylinder PC for the configuration R/d  =  0.2. (paper)

  18. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R.; Yakobson, Boris I.; McCarty, Kevin F.; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S.

    2016-02-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional 'surface-limited' growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to -100 meV at a displacement field of 0.9 V nm-1.

  19. Oxygen-activated growth and bandgap tunability of large single-crystal bilayer graphene

    Science.gov (United States)

    Hao, Yufeng; Wang, Lei; Liu, Yuanyue; Chen, Hua; Wang, Xiaohan; Tan, Cheng; Nie, Shu; Suk, Ji Won; Jiang, Tengfei; Liang, Tengfei; Xiao, Junfeng; Ye, Wenjing; Dean, Cory R.; Yakobson, Boris I.; McCarty, Kevin F.; Kim, Philip; Hone, James; Colombo, Luigi; Ruoff, Rodney S.

    2016-05-01

    Bernal (AB)-stacked bilayer graphene (BLG) is a semiconductor whose bandgap can be tuned by a transverse electric field, making it a unique material for a number of electronic and photonic devices. A scalable approach to synthesize high-quality BLG is therefore critical, which requires minimal crystalline defects in both graphene layers and maximal area of Bernal stacking, which is necessary for bandgap tunability. Here we demonstrate that in an oxygen-activated chemical vapour deposition (CVD) process, half-millimetre size, Bernal-stacked BLG single crystals can be synthesized on Cu. Besides the traditional ‘surface-limited’ growth mechanism for SLG (1st layer), we discovered new microscopic steps governing the growth of the 2nd graphene layer below the 1st layer as the diffusion of carbon atoms through the Cu bulk after complete dehydrogenation of hydrocarbon molecules on the Cu surface, which does not occur in the absence of oxygen. Moreover, we found that the efficient diffusion of the carbon atoms present at the interface between Cu and the 1st graphene layer further facilitates growth of large domains of the 2nd layer. The CVD BLG has superior electrical quality, with a device on/off ratio greater than 104, and a tunable bandgap up to ∼100 meV at a displacement field of 0.9 V nm‑1.

  20. Compound semiconductor alloys: From atomic-scale structure to bandgap bowing

    Energy Technology Data Exchange (ETDEWEB)

    Schnohr, C. S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2015-09-15

    Compound semiconductor alloys such as In{sub x}Ga{sub 1−x}As, GaAs{sub x}P{sub 1−x}, or CuIn{sub x}Ga{sub 1−x}Se{sub 2} are increasingly employed in numerous electronic, optoelectronic, and photonic devices due to the possibility of tuning their properties over a wide parameter range simply by adjusting the alloy composition. Interestingly, the material properties are also determined by the atomic-scale structure of the alloys on the subnanometer scale. These local atomic arrangements exhibit a striking deviation from the average crystallographic structure featuring different element-specific bond lengths, pronounced bond angle relaxation and severe atomic displacements. The latter, in particular, have a strong influence on the bandgap energy and give rise to a significant contribution to the experimentally observed bandgap bowing. This article therefore reviews experimental and theoretical studies of the atomic-scale structure of III-V and II-VI zincblende alloys and I-III-VI{sub 2} chalcopyrite alloys and explains the characteristic findings in terms of bond length and bond angle relaxation. Different approaches to describe and predict the bandgap bowing are presented and the correlation with local structural parameters is discussed in detail. The article further highlights both similarities and differences between the cubic zincblende alloys and the more complex chalcopyrite alloys and demonstrates that similar effects can also be expected for other tetrahedrally coordinated semiconductors of the adamantine structural family.

  1. Density of states governs light scattering in photonic crystals

    CERN Document Server

    García, P D; Froufe-Pérez, Luis S; López, C

    2008-01-01

    We describe a smooth transition from (fully ordered) photonic crystal to (fully disordered) photonic glass that enables us to make an accurate measurement of the scattering mean free path in nanostructured media and, in turn, establishes the dominant role of the density of states. We have found one order of magnitude chromatic variation in the scattering mean free path in photonic crystals for just $\\sim 3%$ shift around the band-gap ($\\sim 27$ nm in wavelength).

  2. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  3. Switchable Electromagnetic Bandgap Surface Wave Antenna

    Directory of Open Access Journals (Sweden)

    Qiang Bai

    2014-01-01

    Full Text Available This paper presents a novel switchable electromagnetic bandgap surface wave antenna that can support both a surface wave and normal mode radiation for communications at 2.45 GHz. In the surface wave mode, the antenna has a monopole-like radiation pattern with a measured gain of 4.4 dBi at ±49° and a null on boresight. In the normal mode, the antenna operates like a back-fed microstrip patch antenna.

  4. Coherent mid-infrared supercontinuum generation in all-solid chalcogenide microstructured fibers with all-normal dispersion

    Science.gov (United States)

    Liu, Lai; Cheng, Tonglei; Nagasaka, Kenshiro; Tong, Hoang Tuan; Suzuki, Takenobu; Ohishi, Yasutake

    2016-02-01

    We report the coherent mid-infrared supercontinuum generation in an all-solid chalcogenide microstructured fiber with all-normal dispersion. The chalcogenide microstructured fiber is four-hole structure with core material of AsSe2 and air holes are replaced by As2S5 glass rods. Coherent mid-infrared supercontinuum light is generated in a 2-cm-long chalcogenide microstructured fiber pumped by a 2.7 μm laser. The simulated and experimental results have a good match and the coherence property of supercontinuum light in the chalcogenide microstructured fiber has been studied by using the complex degree of coherence theory. Coherent mid-infrared supercontinuum generation is extended to 3.3 μm in this work.

  5. Effects of cathode electrolyte interfacial (CEI) layer on long term cycling of all-solid-state thin-film batteries

    Science.gov (United States)

    Wang, Ziying; Lee, Jungwoo Z.; Xin, Huolin L.; Han, Lili; Grillon, Nathanael; Guy-Bouyssou, Delphine; Bouyssou, Emilien; Proust, Marina; Meng, Ying Shirley

    2016-08-01

    All-solid-state lithium-ion batteries have the potential to not only push the current limits of energy density by utilizing Li metal, but also improve safety by avoiding flammable organic electrolyte. However, understanding the role of solid electrolyte - electrode interfaces will be critical to improve performance. In this study, we conducted long term cycling on commercially available lithium cobalt oxide (LCO)/lithium phosphorus oxynitride (LiPON)/lithium (Li) cells at elevated temperature to investigate the interfacial phenomena that lead to capacity decay. STEM-EELS analysis of samples revealed a previously unreported disordered layer between the LCO cathode and LiPON electrolyte. This electrochemically inactive layer grew in thickness leading to loss of capacity and increase of interfacial resistance when cycled at 80 °C. The stabilization of this layer through interfacial engineering is crucial to improve the long term performance of thin-film batteries especially under thermal stress.

  6. All-solid-state lithium-sulfur battery based on a nanoconfined LiBH4 electrolyte

    DEFF Research Database (Denmark)

    Das, Supti; Ngene, Peter; Norby, Poul;

    2016-01-01

    In this work we characterize all-solid-state lithium-sulfur batteries based on nano-confined LiBH4 in mesoporous silica as solid electrolytes. The nano-confined LiBH4 has fast ionic lithium conductivity at room temperature, 0.1 mScm-1, negligible electronic conductivity and its cationic transport...... number (t+ = 0.96), close to unity, demonstrates a purely cationic conductor. The electrolyte has an excellent stability against lithium metal. The behavior of the batteries is studied by cyclic voltammetry and repeated charge/discharge cycles in galvanostatic conditions. The batteries show very good...... performance, delivering high capacities versus sulfur mass, typically 1220 mAhg-1 after 40 cycles at moderate temperature (55°C), 0.03 C rates and working voltage of 2 V....

  7. Anode properties of silicon-rich amorphous silicon suboxide films in all-solid-state lithium batteries

    Science.gov (United States)

    Miyazaki, Reona; Ohta, Narumi; Ohnishi, Tsuyoshi; Takada, Kazunori

    2016-10-01

    This paper reports the effects of introducing oxygen into amorphous silicon films on their anode properties in all-solid-state lithium batteries. Although poor cycling performance is a critical issue in silicon anodes, it has been effectively improved by introducing even a small amount of oxygen, that is, even in Si-rich amorphous silicon suboxide (a-SiOx) films. Because of the small amount of oxygen in the films, high cycling performance has been achieved without lowering the capacity and power density: an a-Si film delivers discharge capacity of 2500 mAh g-1 under high discharge current density of 10 mA cm-2 (35 C). These results demonstrate that a-SiOx is a promising candidate for high-capacity anode materials in solid-state batteries.

  8. An all-solid-state laser source at 671 nm for cold-atom experiments with lithium

    Science.gov (United States)

    Eismann, U.; Gerbier, F.; Canalias, C.; Zukauskas, A.; Trénec, G.; Vigué, J.; Chevy, F.; Salomon, C.

    2012-01-01

    We present an all-solid-state narrow-linewidth laser source emitting 670 mW output power at 671 nm delivered in a diffraction-limited beam. The source is based on a frequency-doubled diode-end-pumped ring laser operating on the 4 F 3/2→4 I 13/2 transition in Nd:YVO4. By using periodically poled potassium titanyl phosphate (ppKTP) in an external buildup cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over 100 GHz is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally, a simplified design based on intra-cavity doubling is described and first results are presented.

  9. Flexible all solid state supercapacitor with high energy density employing black titania nanoparticles as a conductive agent

    Science.gov (United States)

    Zhi, Jian; Yang, Chongyin; Lin, Tianquan; Cui, Houlei; Wang, Zhou; Zhang, Hui; Huang, Fuqiang

    2016-02-01

    Increasing the electrical conductivity of pseudocapacitive materials without changing their morphology is an ideal structural solution to realize both high electrochemical performance and superior flexibility for an all solid state supercapacitor (ASSSC). Herein, we fabricate a flexible ASSSC device employing black titania (TiO2-x:N) decorated two-dimensional (2D) NiO nanosheets as the positive electrode and mesoporous graphene as the negative electrode. In this unique design, NiO nanosheets are used as pseudocapacitive materials and TiO2-x:N nanoparticles serve as the conductive agent. Owing to the excellent electrical conductivity of TiO2-x:N and well defined ``particle on sheet'' planar structure of NiO/TiO2-x:N composites, the 2D morphology of the decorated NiO nanosheets is completely retained, which efficiently reinforces the pseudocapacitive activity and flexibility of the whole all solid state device. The maximum specific capacitance of fabricated the NiO/TiO2-x:N//mesoporous graphene supercapacitor can reach 133 F g-1, which is 2 and 4 times larger than the values of the NiO based ASSSC employing graphene and carbon black as the conductive agent, respectively. In addition, the optimized ASSSC displays intriguing performances with an energy density of 47 W h kg-1 in a voltage region of 0-1.6 V, which is, to the best of our knowledge, the highest value for flexible ASSSC devices. The impressive results presented here may pave the way for promising applications of black titania in high energy density flexible storage systems.Increasing the electrical conductivity of pseudocapacitive materials without changing their morphology is an ideal structural solution to realize both high electrochemical performance and superior flexibility for an all solid state supercapacitor (ASSSC). Herein, we fabricate a flexible ASSSC device employing black titania (TiO2-x:N) decorated two-dimensional (2D) NiO nanosheets as the positive electrode and mesoporous graphene as the

  10. An All-Solid-State Fiber-Shaped Aluminum-Air Battery with Flexibility, Stretchability, and High Electrochemical Performance.

    Science.gov (United States)

    Xu, Yifan; Zhao, Yang; Ren, Jing; Zhang, Ye; Peng, Huisheng

    2016-07-01

    Owing to the high theoretical energy density of metal-air batteries, the aluminum-air battery has been proposed as a promising long-term power supply for electronics. However, the available energy density from the aluminum-air battery is far from that anticipated and is limited by current electrode materials. Herein we described the creation of a new family of all-solid-state fiber-shaped aluminum-air batteries with a specific capacity of 935 mAh g(-1) and an energy density of 1168 Wh kg(-1) . The synthesis of an electrode composed of cross-stacked aligned carbon-nanotube/silver-nanoparticle sheets contributes to the remarkable electrochemical performance. The fiber shape also provides the aluminum-air batteries with unique advantages; for example, they are flexible and stretchable and can be woven into a variety of textiles for large-scale applications. PMID:27193636

  11. Modulation of superconducting critical temperature in niobium film by using all-solid-state electric-double-layer transistor

    International Nuclear Information System (INIS)

    An all-solid-state electric-double-layer transistor (EDLT) was fabricated for electrical modulation of the superconducting critical temperature (Tc) of Nb film epitaxially grown on α-Al2O3 (0001) single crystal. In an experiment, Tc was modulated from 8.33 to 8.39 K while the gate voltage (VG) was varied from 2.5 to −2.5 V. The specific difference of Tc for the applied VG was 12 mK/V, which is larger than that of an EDLT composed of ionic liquid. A Tc enhancement of 300 mK was found at the Li4SiO4/Nb film interface and is attributed to an increase in density of states near the Fermi level due to lattice constant modulation. This solid electrolyte gating method should enable development of practical superconducting devices highly compatible with other electronic devices

  12. One-pot preparation of new copolymer electrolytes with tunable network structure for all-solid-state lithium battery

    Science.gov (United States)

    Chen, Bo; Xu, Qiang; Huang, Zhen; Zhao, Yanran; Chen, Shaojie; Xu, Xiaoxiong

    2016-11-01

    A new class of copolymer electrolytes with tunable network structure is successfully designed and prepared via a facile one-pot reaction. The trimethylolpropane triglycidyl ether (TMPEG) is cross-linked with poly (ethylene glycol) diamine (NPEG) to create well-defined solid network polymer electrolyte (SNPE). The network structure could be tuned by changing the molar ratio of TMPEG and NPEG or the molecular weight of NPEG. The effects of molecular weight of NPEG and molar ratio of EO/Li+ on the ionic conductivity are systematically investigated. The optimal electrolyte TMPEG-NPEG4K[2:1]-16:1 presents a maximum conductivity of 1.10 × 10-4 S cm-1 under 30 °C, and an 18-fold ionic conductivity enhancement in that of PEO-based electrolyte. Furthermore, it also exhibits wide electrochemical window (0-5.4 V), excellent compatibility with metallic Li, and superior mechanical properties. The all-solid-state lithium batteries LiFePO4/Li are assembled with TMPEG-NPEG4K[2:1]-16:1 electrolyte, and present good cycling and rate performance under 60 °C. The initial discharge specific capacities of the batteries are 161.7 mAh g-1 at 0.2 C and 132.7 mAh g-1 at 1 C, and the capacity retention ratio can be retained at 90.6% and 90.5% after 100 cycles. This new copolymer electrolyte may become a promising candidate for applications in all-solid-state lithium battery.

  13. Two-Dimentional Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Dridi, Kim

    1999-01-01

    dielectric function. This is analogous to semiconductors, where electronic bandgaps exist due to the periodic arrangement of atoms. As is also the case for semiconductor structures, photonic bandgap structures may become of even greater value when defects are introduced. In particular, point defects make...... possible a novel class of optical microcavities, whereas line defects make possible a novel class of waveguides. In this paper we will analyze two-dimensional photonic crystal waveguides based on photonic crystals with rods arranged on a triangular and a square lattice using a plane-wave expansion method...... and a finite-difference-time-domain (FDTD) method. Design parameters, i.e. dielectric constants, rod diameter and waveguide width, where these waveguides are single-moded and multi-moded will be given. We will also show our recent results regarding the energy-flow (the Poynting vector) in these waveguides...

  14. Contact and Bandgap Engineering in Two Dimensional Crystal

    Science.gov (United States)

    Chu, Tao

    At the heart of semiconductor research, bandgap is one of the key parameters for materials and determine their applications in modern technologies. For traditional bulk semiconductors, the bandgap is determined by the chemical composition and specific arrangement of the crystal lattices, and usually invariant during the device operation. Nevertheless, it is highly desirable for many optoelectronic and electronic applications to have materials with continuously tunable bandgap available. In the past decade, 2D layered materials including graphene and transition metal dichalcogenides (TMDs) have sparked interest in the scientific community, owing to their unique material properties and tremendous potential in various applications. Among many newly discovered properties that are non-existent in bulk materials, the strong in-plane bonding and weak van der Waals inter-planar interaction in these 2D layered structures leads to a widely tunable bandgap by electric field. This provides an extra knob to engineer the fundamental material properties and open a new design space for novel device operation. This thesis focuses on this field controlled dynamic bandgap and can be divided into three parts: (1) bilayer graphene is the first known 2D crystal with a bandgap can be continuously tuned by electric field. However, the electrical transport bandgaps is much smaller than both theoretical predictions and extracted bandgaps from optical measurements. In the first part of the thesis, the limiting factors of preventing achieving a large transport bandgap in bilayer graphene are investigated and different strategies to achieve a large transport bandgap are discussed, including the vertically scaling of gate oxide and patterning channel into ribbon structure. With a record large transport bandgap of ~200meV, a dual-gated semiconducting bilayer graphene P/N junction with extremely scaled gap of 20nm in-between is fabricated. A tunable local maxima feature, associated with 1D v

  15. Near-Infrared Sub-Bandgap All-Silicon Photodetectors: State of the Art and Perspectives

    Directory of Open Access Journals (Sweden)

    Luigi Sirleto

    2010-11-01

    Full Text Available Due to recent breakthroughs, silicon photonics is now the most active discipline within the field of integrated optics and, at the same time, a present reality with commercial products available on the market. Silicon photodiodes are excellent detectors at visible wavelengths, but the development of high-performance photodetectors on silicon CMOS platforms at wavelengths of interest for telecommunications has remained an imperative but unaccomplished task so far. In recent years, however, a number of near-infrared all-silicon photodetectors have been proposed and demonstrated for optical interconnect and power-monitoring applications. In this paper, a review of the state of the art is presented. Devices based on mid-bandgap absorption, surface-state absorption, internal photoemission absorption and two-photon absorption are reported, their working principles elucidated and their performance discussed and compared.

  16. Tunable fluorescence enhancement based on bandgap-adjustable 3D Fe3O4 nanoparticles

    Science.gov (United States)

    Hu, Fei; Gao, Suning; Zhu, Lili; Liao, Fan; Yang, Lulu; Shao, Mingwang

    2016-06-01

    Great progress has been made in fluorescence-based detection utilizing solid state enhanced substrates in recent years. However, it is still difficult to achieve reliable substrates with tunable enhancement factors. The present work shows liquid fluorescence enhanced substrates consisting of suspensions of Fe3O4 nanoparticles (NPs), which can assemble 3D photonic crystal under the external magnetic field. The photonic bandgap induced by the equilibrium of attractive magnetic force and repulsive electrostatic force between adjacent Fe3O4 NPs is utilized to enhance fluorescence intensity of dye molecules (including R6G, RB, Cy5, DMTPS-DCV) in a reversible and controllable manner. The results show that a maximum of 12.3-fold fluorescence enhancement is realized in the 3D Fe3O4 NP substrates without the utilization of metal particles for PCs/DMTPS-DCV (1.0 × 10‑7 M, water fraction (f w) = 90%).

  17. Bandgap engineering of InGaAsP/InP laser structure by photo-absorption-induced point defects

    Science.gov (United States)

    Kaleem, Mohammad; Nazir, Sajid; Saqib, Nazar Abbas

    2016-03-01

    Integration of photonic components on the same photonic wafer permits future optical communication systems to be dense and advanced performance. This enables very fast information handling between photonic active components interconnected through passive optical low loss channels. We demonstrate the UV-Laser based Quantum Well Intermixing (QWI) procedure to engineer the band-gap of compressively strained InGaAsP/InP Quantum Well (QW) laser material. We achieved around 135nm of blue-shift by simply applying excimer laser (λ= 248nm). The under observation laser processed material also exhibits higher photoluminescence (PL) intensity. Encouraging experimental results indicate that this simple technique has the potential to produce photonic integrated devices and circuits.

  18. Electrically Tunable Bandgaps in Bilayer MoS₂.

    Science.gov (United States)

    Chu, Tao; Ilatikhameneh, Hesameddin; Klimeck, Gerhard; Rahman, Rajib; Chen, Zhihong

    2015-12-01

    Artificial semiconductors with manufactured band structures have opened up many new applications in the field of optoelectronics. The emerging two-dimensional (2D) semiconductor materials, transition metal dichalcogenides (TMDs), cover a large range of bandgaps and have shown potential in high performance device applications. Interestingly, the ultrathin body and anisotropic material properties of the layered TMDs allow a wide range modification of their band structures by electric field, which is obviously desirable for many nanoelectronic and nanophotonic applications. Here, we demonstrate a continuous bandgap tuning in bilayer MoS2 using a dual-gated field-effect transistor (FET) and photoluminescence (PL) spectroscopy. Density functional theory (DFT) is employed to calculate the field dependent band structures, attributing the widely tunable bandgap to an interlayer direct bandgap transition. This unique electric field controlled spontaneous bandgap modulation approaching the limit of semiconductor-to-metal transition can open up a new field of not yet existing applications. PMID:26560813

  19. Partial Oxidized Arsenene: Emerging Tunable Direct Bandgap Semiconductor

    Science.gov (United States)

    Wang, Yu-Jiao; Zhou, Kai-Ge; Yu, Geliang; Zhong, Xing; Zhang, Hao-Li

    2016-01-01

    Arsenene, as a member of the Group V elemental two-dimensional materials appears on the horizon, has shown great prospects. However, its indirect bandgap limits the applications in optoelectronics. In this theoretical work, we reported that partial oxidation can tune the indirect bandgap of arsenene into the direct one. Attributed to the enthalpy decreasing linear to the oxygen ratio, partial oxidized arsenene can be controllably produced by the progressive oxidation under low temperature. Importantly, by increasing the oxygen content from 1O/18As to 18O/18As, the oxidation can narrow the direct bandgap of oxidized arsenene from 1.29 to 0.02 eV. The bandgap of partial oxidized arsenene is proportional to the oxygen content. Consequently, the partial oxidized arsenene with tunable direct bandgap has great potentials in the high efficient infra light emitter and photo-voltaic devices. PMID:27114052

  20. Partial Oxidized Arsenene: Emerging Tunable Direct Bandgap Semiconductor

    Science.gov (United States)

    Wang, Yu-Jiao; Zhou, Kai-Ge; Yu, Geliang; Zhong, Xing; Zhang, Hao-Li

    2016-04-01

    Arsenene, as a member of the Group V elemental two-dimensional materials appears on the horizon, has shown great prospects. However, its indirect bandgap limits the applications in optoelectronics. In this theoretical work, we reported that partial oxidation can tune the indirect bandgap of arsenene into the direct one. Attributed to the enthalpy decreasing linear to the oxygen ratio, partial oxidized arsenene can be controllably produced by the progressive oxidation under low temperature. Importantly, by increasing the oxygen content from 1O/18As to 18O/18As, the oxidation can narrow the direct bandgap of oxidized arsenene from 1.29 to 0.02 eV. The bandgap of partial oxidized arsenene is proportional to the oxygen content. Consequently, the partial oxidized arsenene with tunable direct bandgap has great potentials in the high efficient infra light emitter and photo-voltaic devices.

  1. Review of wide band-gap semiconductors technology

    Directory of Open Access Journals (Sweden)

    Jin Haiwei

    2016-01-01

    Full Text Available Silicon carbide (SiC and gallium nitride (GaN are typical representative of the wide band-gap semiconductor material, which is also known as third-generation semiconductor materials. Compared with the conventional semiconductor silicon (Si or gallium arsenide (GaAs, wide band-gap semiconductor has the wide band gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology research in various countries. This article describes the research agenda of United States and European in this area, focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing challenge of the wide band-gap technology.

  2. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, A.M.

    1995-04-01

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  3. Photon-photon colliders

    International Nuclear Information System (INIS)

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R ampersand D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy

  4. Wide bandgap materials in future electronic applications

    International Nuclear Information System (INIS)

    A brief overview of the impact that wide bandgap materials have, and will have in the future, on the development of (micro)electronic devices, circuits, and systems is presented. It is held that electronic control systems and thus their applications fall into three temperature domains, delineated by the maximum use temperature of the semiconductor systems with which they are equipped: the current low temperature (- 100 to 200 oC) domain dominated by silicon; a medium temperature range (200 - ∼600oC), in which GaN and AlN provide the transition to SiC; and a high temperature domain (600-1300 oC) not yet covered by any one material system and in which research and development of c-BN based composites can at first, as passives, enhance performance in all three temperature/application ranges. Current developments in most application areas are cost-not performance-driven. (author)

  5. Bandgap engineering of GaN nanowires

    Science.gov (United States)

    Ming, Bang-Ming; Wang, Ru-Zhi; Yam, Chi-Yung; Xu, Li-Chun; Lau, Woon-Ming; Yan, Hui

    2016-05-01

    Bandgap engineering has been a powerful technique for manipulating the electronic and optical properties of semiconductors. In this work, a systematic investigation of the electronic properties of [0001] GaN nanowires was carried out using the density functional based tight-binding method (DFTB). We studied the effects of geometric structure and uniaxial strain on the electronic properties of GaN nanowires with diameters ranging from 0.8 to 10 nm. Our results show that the band gap of GaN nanowires depends linearly on both the surface to volume ratio (S/V) and tensile strain. The band gap of GaN nanowires increases linearly with S/V, while it decreases linearly with increasing tensile strain. These linear relationships provide an effect way in designing GaN nanowires for their applications in novel nano-devices.

  6. Modulation of superconducting critical temperature in niobium film by using all-solid-state electric-double-layer transistor

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Takashi, E-mail: TSUCHIYA.Takashi@nims.go.jp, E-mail: TERABE.Kazuya@nims.go.jp; Moriyama, Satoshi; Terabe, Kazuya, E-mail: TSUCHIYA.Takashi@nims.go.jp, E-mail: TERABE.Kazuya@nims.go.jp; Aono, Masakazu [International Center for Materials Nanoarchitechtonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-07-06

    An all-solid-state electric-double-layer transistor (EDLT) was fabricated for electrical modulation of the superconducting critical temperature (T{sub c}) of Nb film epitaxially grown on α-Al{sub 2}O{sub 3} (0001) single crystal. In an experiment, T{sub c} was modulated from 8.33 to 8.39 K while the gate voltage (V{sub G}) was varied from 2.5 to −2.5 V. The specific difference of T{sub c} for the applied V{sub G} was 12 mK/V, which is larger than that of an EDLT composed of ionic liquid. A T{sub c} enhancement of 300 mK was found at the Li{sub 4}SiO{sub 4}/Nb film interface and is attributed to an increase in density of states near the Fermi level due to lattice constant modulation. This solid electrolyte gating method should enable development of practical superconducting devices highly compatible with other electronic devices.

  7. Effect of Molecular Weight on Mechanical and Electrochemical Performance of All Solid-State Polymer Electrolyte Membranes

    Science.gov (United States)

    He, Ruixuan; Ward, Daniel; Echeverri, Mauricio; Kyu, Thein

    2015-03-01

    Guided by ternary phase diagrams of polyethylene glycol diacrylate (PEGDA), succinonitrile plasticizer, and LiTFSI salt, completely amorphous solid-state transparent polymer electrolyte membranes (ss-PEM) were fabricated by UV irradiation in the isotropic melt state. Effects of PEGDA molecular weight (700 vs 6000 g/mol) on ss-PEM performance were investigated. These amorphous PEMs have superionic room temperature ionic conductivity of ~10-3 S/cm, whereby PEGDA6000-PEM outperforms its PEGDA700 counterpart, which may be ascribed to lower crosslinking density and greater segmental mobility. The longer chain between crosslinked points of PEGDA6000-PEM is responsible for greater extensibility of ~80% versus ~7% of PEGDA700-PEM. Besides, both PEMs exhibited thermal stability up to 120 °C and electrochemical stability versus Li+/Li up to 4.7V. LiFePO4/PEM/Li and Li4Ti5O12 /PEM/Li half-cells exhibited stable cyclic behavior up to 50 cycles tested with a capacity of ~140mAh/g, suggesting that LiFePO4/PEM/Li4Ti5O12 may be a promising full-cell for all solid-state lithium battery. We thank NSF-DMR 1161070 for providing funding of this project.

  8. Optical rogue waves in an all-solid-state laser with a saturable absorber: importance of the spatial effects

    International Nuclear Information System (INIS)

    We study the features of the optical rogue waves (ORWs) observed in an all-solid-state (Cr:YAG+Nd:YVO4) passively-Q-switched laser, which is a system of wide practical interest. The extreme events appear as isolated pulses of extraordinary intensity during the chaotic regime of this laser. The standard theoretical description (three-level rate equations for a single mode of the field and a two-level system for the absorber) does predict the existence of many of the observed dynamical features, including chaos, but it fails to predict the existence of ORWs. Faced with the problem of improving the theoretical description, we find that ORWs are observed only when the Fresnel number of the laser cavity and the embedding dimension of the attractor reconstructed from the experimental time series are high, and the laser spot profile has a spatially complex structure. These results suggest that spatial effects are an essential ingredient in the formation of ORWs in this type of laser. (paper)

  9. Bottom-Up Fabrication of Activated Carbon Fiber for All-Solid-State Supercapacitor with Excellent Electrochemical Performance.

    Science.gov (United States)

    Ma, Wujun; Chen, Shaohua; Yang, Shengyuan; Chen, Wenping; Weng, Wei; Zhu, Meifang

    2016-06-15

    Activated carbon (AC) is the most extensively used electrode material for commercial electric double layer capacitors (EDLC) given its high specific surface area (SSA) and moderate cost. However, AC is primarily used in the forms of powders, which remains a big challenge in developing AC powders into continuous fibers. If AC powders can be processed into fiber, then they may be scaled up for practical applications to supercapacitors (SCs) and satisfy the rapid development of flexible electronics. Herein, we report a bottom-up method to fabricate AC fiber employing graphene oxide (GO) as both dispersant and binder. After chemical reduction, the fiber has high electrical conductivity (185 S m(-1)), high specific surface area (1476.5 m(2) g(-1)), and good mechanical flexibility. An all solid-state flexible SC was constructed using the prepared fiber as electrode, which is free of binder, conducting additive, and additional current collector. The fiber-shaped SC shows high capacitance (27.6 F cm(-3) or 43.8 F g(-1), normalized to the two-electrode volume), superior cyclability (90.4% retention after 10 000 cycles), and good bendability (96.8% retention after bending 1000 times). PMID:27239680

  10. Densely-packed graphene/conducting polymer nanoparticle papers for high-volumetric-performance flexible all-solid-state supercapacitors

    Science.gov (United States)

    Yang, Chao; Zhang, Liling; Hu, Nantao; Yang, Zhi; Wei, Hao; Xu, Zhichuan J.; Wang, Yanyan; Zhang, Yafei

    2016-08-01

    Graphene-based all-solid-state supercapacitors (ASSSCs) are one of the most ideal candidates for high-performance flexible power sources. The achievement of high volumetric energy density is highly desired for practical application of this type of ASSSCs. Here, we present a facile method to boost volumetric performances of graphene-based flexible ASSSCs through incorporation of ultrafine polyaniline-poly(4-styrenesulfonate) (PANI-PSS) nanoparticles in reduced graphene oxide (rGO) papers. A compact structure is obtained via intimate contact and π-π interaction between PANI-PSS nanoparticles and rGO sheets. The hybrid paper electrode with the film thickness of 13.5 μm, shows an extremely high volumetric specific capacitance of 272 F/cm3 (0.37 A/cm3 in a three-electrode cell). The assembled ASSSCs show a large volumetric specific capacitance of 217 F/cm3 (0.37 A/cm3 in a two-electrode cell), high volumetric energy and power density, excellent capacitance stability, small leakage current as well as low self-discharge characteristics, revealing the usefulness of this robust hybrid paper for high-performance flexible energy storage devices.

  11. Proton conductive tantalum oxide thin film deposited by reactive DC magnetron sputtering for all-solid-state switchable mirror

    Science.gov (United States)

    Tajima, K.; Yamada, Y.; Bao, S.; Okada, M.; Yoshimura, K.

    2008-03-01

    Our developed all-solid-state switchable mirror as a smart window is consisted in multi-layer of Mg4Ni/Pd/Ta2O5/WO3/ITO/glass and can switch reversibly from the reflective state to the transparent one. The development of high performance solid electrolyte thin film of Ta2O5 is important for fast speed switching and high durability of the device. In this work, we have investigated the electrochemical property of Ta2O5 thin film deposited by reactive DC magnetron sputtering. The effect of thickness on electrochemical and proton conductivities of Ta2O5 thin film was investigated. The Ta2O5 thin film with a thickness of 400 nm had better proton conductivity of 1.5×10-9 S/cm measured by AC impedance method. The transmittance at wavelength of 670 nm of the device with 400 nm thick Ta2O5 thin film was changed from 0.1% (reflective state) to 51% (transparent state) within 10 s by applying voltage of 5 V. The device showed high durability up to two-thousand switching cycles.

  12. Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All-Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Shim, Jimin; Bae, Ki Yoon; Kim, Hee Joong; Lee, Jin Hong; Kim, Dong-Gyun; Yoon, Woo Young; Lee, Jong-Chan

    2015-12-21

    Solid polymer electrolytes (SPEs) for all-solid-state lithium-ion batteries are prepared by simple one-pot polymerization induced by ultraviolet (UV) light using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as an ion-conducting monomeric unit and tannic acid (TA)-based crosslinking agent and plasticizer. The crosslinking agent and plasticizer based on natural resources are obtained from the reaction of TA with glycidyl methacrylate and glycidyl poly(ethylene glycol), respectively. Dimensionally stable free-standing SPE having a large ionic conductivity of 5.6×10(-4)  Scm(-1) at room temperature can be obtained by the polymerization of PEGMA into P(PEGMA) with a very small amount (0.1 wt %) of the crosslinking agent and 2.0 wt % of the plasticizer. The ionic conductivity value of SPE with a crosslinked structure is one order of magnitude larger than that of linear P(PEGMA) in the waxy state.

  13. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging.

    Science.gov (United States)

    Zhao, Qiaole; Schelen, Ben; Schouten, Raymond; van den Oever, Rein; Leenen, René; van Kuijk, Harry; Peters, Inge; Polderdijk, Frank; Bosiers, Jan; Raspe, Marcel; Jalink, Kees; Geert Sander de Jong, Jan; van Geest, Bert; Stoop, Karel; Young, Ian Ted

    2012-12-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device design in a frequency-domain FLIM system. The first stage of evaluation for the camera has been carried out. Camera characteristics such as noise distribution, dark current influence, camera gain, sampling density, sensitivity, linearity of photometric response, and optical transfer function have been studied through experiments. We are able to do lifetime measurement using our modulated, electron-multiplied fluorescence lifetime imaging microscope (MEM-FLIM) camera for various objects, e.g., fluorescein solution, fixed green fluorescent protein (GFP) cells, and GFP-actin stained live cells. A detailed comparison of a conventional microchannel plate (MCP)-based FLIM system and the MEM-FLIM system is presented. The MEM-FLIM camera shows higher resolution and a better image quality. The MEM-FLIM camera provides a new opportunity for performing frequency-domain FLIM.

  14. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, Andrew M.

    1996-01-01

    Since the seminal work by Ginsburg, et al., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention [1]. A 1990 article by V.I. Telnov describes the situation at that time [2]. In March 1994, the first workshop on this subject was held [3]. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons—the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  15. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  16. Nonlocal hyperconcentration on entangled photons using photonic module system

    Science.gov (United States)

    Cao, Cong; Wang, Tie-Jun; Mi, Si-Chen; Zhang, Ru; Wang, Chuan

    2016-06-01

    Entanglement distribution will inevitably be affected by the channel and environment noise. Thus distillation of maximal entanglement nonlocally becomes a crucial goal in quantum information. Here we illustrate that maximal hyperentanglement on nonlocal photons could be distilled using the photonic module and cavity quantum electrodynamics, where the photons are simultaneously entangled in polarization and spatial-mode degrees of freedom. The construction of the photonic module in a photonic band-gap structure is presented, and the operation of the module is utilized to implement the photonic nondestructive parity checks on the two degrees of freedom. We first propose a hyperconcentration protocol using two identical partially hyperentangled initial states with unknown coefficients to distill a maximally hyperentangled state probabilistically, and further propose a protocol by the assistance of an ancillary single photon prepared according to the known coefficients of the initial state. In the two protocols, the total success probability can be improved greatly by introducing the iteration mechanism, and only one of the remote parties is required to perform the parity checks in each round of iteration. Estimates on the system requirements and recent experimental results indicate that our proposal is realizable with existing or near-further technologies.

  17. An All-Solid-State, Room-Temperature, Heterodyne Receiver for Atmospheric Spectroscopy at 1.2 THz

    Science.gov (United States)

    Siles, Jose V.; Mehdi, Imran; Schlecht, Erich T.; Gulkis, Samuel; Chattopadhyay, Goutam; Lin, Robert H.; Lee, Choonsup; Gill, John J.; Thomas, Bertrand; Maestrini, Alain E.

    2013-01-01

    Heterodyne receivers at submillimeter wavelengths have played a major role in astrophysics as well as Earth and planetary remote sensing. All-solid-state heterodyne receivers using both MMIC (monolithic microwave integrated circuit) Schottky-diode-based LO (local oscillator) sources and mixers are uniquely suited for long-term planetary missions or Earth climate monitoring missions as they can operate for decades without the need for any active cryogenic cooling. However, the main concern in using Schottky-diode-based mixers at frequencies beyond 1 THz has been the lack of enough LO power to drive the devices because 1 to 3 mW are required to properly pump Schottky diode mixers. Recent progress in HEMT- (high-electron-mobility- transistor) based power amplifier technology, with output power levels in excess of 1 W recently demonstrated at W-band, as well as advances in MMIC Schottky diode circuit technology, have led to measured output powers up to 1.4 mW at 0.9 THz. Here the first room-temperature tunable, all-planar, Schottky-diode-based receiver is reported that is operating at 1.2 THz over a wide (˜20%) bandwidth. The receiver front-end (see figure) consists of a Schottky-diode-based 540 to 640 GHz multiplied LO chain (featuring a cascade of W-band power amplifiers providing around 120 to 180 mW at W-band), a 200-GHz MMIC frequency doubler, and a 600-GHz MMIC frequency tripler, plus a biasable 1.2-THz MMIC sub-harmonic Schottky-diode mixer. The LO chain has been designed, fabricated, and tested at JPL and provides around 1 to 1.5 mW at 540 o 640 GHz. The sub-harmonic mixer consists of two Schottky diodes on a thin GaAs membrane in an anti-parallel configuration. An integrated metal insulator metal (MIM) capacitor has been included on-chip to allow dc bias for the Schottky diodes. A bias voltage of around 0.5 V/diode is necessary to reduce the LO power required down to the 1 to 1.5 mW available from the LO chain. The epilayer thickness and doping profiles have

  18. All-solid-state potentiometric sensors for ascorbic acid by using a screen-printed compatible solid contact

    Energy Technology Data Exchange (ETDEWEB)

    Veltsistas, Panayotis G.; Prodromidis, Mamas I.; Efstathiou, Constantinos

    2004-01-23

    The development of all-solid-state potentiometric ion selective electrodes for monitoring of ascorbic acid, by using a screen-printed compatible solid contact is described. The applied methodology is based on the use of PVC membrane modified with some firstly-tested ionophores (triphenyltin(IV)chloride, triphenyltin(IV)hydroxide and palmitoyl-L-ascorbic acid) and a novel one synthesized in our laboratory (dibutyltin(IV) diascorbate). Synthesis protocol and some preliminary identification studies are given. A conductive graphite-based polymer thick film ink was used as an internal solid contact between the graphite electrode and the PVC membrane. The presence and the nature of the solid contact (plain or doped with lanthanum 2,6-dichlorophenolindophenol (DCPI)) seem to enhance the analytical performance of the electrodes in terms of sensitivity, dynamic range, and response time. The analytical performance of the constructed electrodes was evaluated with potentiometry, constant-current chronopotentiometry and electrochemical impedance spectroscopy (EIS). The interference effect of various compounds was also tested. The potential response of the optimized Ph{sub 3}SnCl-based electrode was linear against ascorbic acid concentration range 0.005-5.0 mM. The applicability of the proposed sensors in real samples was also tested. The detection limit was 0.002 mM ascorbic acid (50 mM phosphate, pH 5 in 50 mM KCl). The slope of the electrodes was super-Nernstian and pH dependent, indicating a mechanism involving a combination of charge transfer and ion exchange processes. Fabrication of screen-printed ascorbate ISEs has also been demonstrated.

  19. Effects of sintering temperature on interfacial structure and interfacial resistance for all-solid-state rechargeable lithium batteries

    Science.gov (United States)

    Kato, Takehisa; Yoshida, Ryuji; Yamamoto, Kazuo; Hirayama, Tsukasa; Motoyama, Munekazu; West, William C.; Iriyama, Yasutoshi

    2016-09-01

    Sintering processes yield a mutual diffusion region at the electrode/solid electrolyte interface, which is considered as a crucial problem for developing large-sized all-solid-state rechargeable lithium batteries with high power density. This work focuses on the interface between LiNi1/3Co1/3Mn1/3O2 (NMC) and NASICON-structured Li+ conductive glass ceramics solid electrolyte (Li2Osbnd Al2O3sbnd SiO2sbnd P2O5sbnd TiO2sbnd GeO2: LATP sheet (AG-01)), and investigates the effects of sintering temperature on interfacial structure and interfacial resistance at the NMC/LATP sheet. Thin films of NMC were fabricated on the LATP sheets at 700 °C or 900 °C as a model system. We found that the thickness of the mutual diffusion region was almost the same, ca. 30 nm, in these two samples, but the NMC film prepared at 900 °C had three orders of magnitude larger interfacial resistance than the NMC film prepared at 700 °C. Around the interface between the NMC film prepared at 900 °C and the LATP sheet, Co in the NMC accumulates as a reduced valence and lithium-free impurity crystalline phase will be also formed. These two problems must contribute to drastic increasing of interfacial resistance. Formation of de-lithiated NMC around the interface and its thermal instability at higher temperature may be considerable reason to induce these problems.

  20. Towards self-similar propagation in a dispersion tailored and highly nonlinear segmented bandgap fiber at 2.8 micron

    CERN Document Server

    Biswas, Piyali; Biswas, Abhijit; Pal, Bishnu P

    2016-01-01

    We numerically demonstrate self-similar propagation of parabolic optical pulses through a highly nonlinear and passive specialty photonic bandgap fiber at 2.8 micron. In this context, we have proposed a scheme endowed with a rapidly varying, but of nearly-mean-zero longitudinal dispersion and modulated nonlinear profile in order to achieve self-similarity of the formed parabolic pulse propagating over longer distances. To implement the proposed scheme, we have designed a segmented bandgap fiber with suitably tapered counterparts to realize such customized dispersion with chalchogenide glass materials. A self-similar parabolic pulse with full-width-at-half-maxima of 4.12 ps and energy of ~ 39 pJ as been achieved at the output. Along with a linear chirp spanning over the entire pulse duration, 3dB spectral broadening of about 38 nm at the output has been reported.

  1. Large-bandwidth planar photonic crystal waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Lavrinenko, Andrei

    2002-01-01

    A general design principle is presented for making finite-height photonic crystal waveguides that support leakage-free guidance of light over large frequency intervals. The large bandwidth waveguides are designed by introducing line defects in photonic crystal slabs, where the material in the line...... defect has appropriate dispersion properties relative to the photonic crystal slab material surrounding the line defect. A three-dimensional theoretical analysis is given for large-bandwidth waveguide designs based on a silicon-air photonic crystal slab suspended in air. In one example, the leakage......-free single-mode guidance is found for a large frequency interval covering 60% of the photonic band-gap....

  2. Design of Bandgap Reference in Switching Power Supply

    Institute of Scientific and Technical Information of China (English)

    XU Li; NIU Ping-juan; FU Xian-song; DING Ke; PENG Xiao-lei

    2009-01-01

    A bandgap voltage reference is designed to meet the requirements of low power loss,low temperature coefficient and high power source rejection ratio(PSRR) in the intergrated circuit.Based on the analysis of conventional bandgap reference circuit,and combined with the integral performance of IC,the specific design index of the bandgap reference is put forward.In the meantime,the circuit and the layout are designed with Chartered 0.35 μm dual gate CMOS process.The simulation result shows that the coefficient is less than 30ppm/℃ with the temperature from -50℃ to 150℃. The bandgap reference has the characteristics of low power and high PSRR.

  3. High Power Wide Bandgap Engineered MMW MMIC Transceiver Project

    Data.gov (United States)

    National Aeronautics and Space Administration — During this phase I SBIR effort unique proven lattice and bandgap engineering techniques will be utilized to epitaxially grow InAlAs / InGaAs on GaN substrate for...

  4. A bandgap phenomenon in non-periodic plasmonic waveguides

    CERN Document Server

    Shaidiuk, Viacheslav; Park, Namkyoo

    2015-01-01

    The phenomenon of a dispersion bandgap opening between low-loss spectral windows of odd and even plasmonic modes in a layered insulator-metal-insulator plasmonic waveguide is introduced. Beginning with a three layer plasmonic dispersion relation, we explain and numerically confirm the existence of the plasmonic bandgap, and investigate its properties at a very broad spectrum range from ultraviolet to far infrared. The nature of the observed bandgap opening is explained in terms of the near-zero value of an effective permittivity for plasmonic modes in the waveguide. The adjustment of the plasmonic bandgap spectrum is demonstrated with the structural modification of the plasmonic waveguide. As an application example, we illustrate a new concept of coupling control between surface plasmons and free-space excitation waves, by employing a tapered non-adiabatic insulator-metal-insulator waveguide.

  5. Bandgap tuning in armchair MoS2 nanoribbon

    Science.gov (United States)

    Yue, Qu; Chang, Shengli; Kang, Jun; Zhang, Xueao; Shao, Zhengzheng; Qin, Shiqiao; Li, Jingbo

    2012-08-01

    We report on the first-principles calculations of bandgap modulation in armchair MoS2 nanoribbon (AMoS2NR) by transverse and perpendicular electric fields respectively. In the monolayer AMoS2NR case, it is shown that the bandgap can be significantly reduced and be closed by transverse field, whereas the bandgap modulation is absent under perpendicular field. The critical strength of transverse field for gap closure decreases as ribbon width increases. In the multilayer AMoS2NR case, in contrast, it is shown that the bandgap can be effectively reduced by both transverse and perpendicular fields. Nevertheless, it seems that the two fields exhibit different modulation effects on the gap. The critical strength of perpendicular field for gap closure decreases with increasing number of layers, while the critical strength of transverse field is almost independent of it.

  6. CMOS bandgap references and temperature sensors and their applications

    OpenAIRE

    Wang, G.

    2005-01-01

    Two main parts have been presented in this thesis: device characterization and circuit. In integrated bandgap references and temperature sensors, the IC(VBE, characteristics of bipolar transistors are used to generate the basic signals with high accuracy. To investigate the possibilities to fabricate high-precision bandgap references and temperature sensors in low-cost CMOS technology, the electrical characteristics of substrate bipolar pnp transistors have been investigated over a wide tempe...

  7. Bandgap Restructuring of the Layered Semiconductor Gallium Telluride in Air.

    Science.gov (United States)

    Fonseca, Jose J; Tongay, Sefaattin; Topsakal, Mehmet; Chew, Annabel R; Lin, Alan J; Ko, Changhyun; Luce, Alexander V; Salleo, Alberto; Wu, Junqiao; Dubon, Oscar D

    2016-08-01

    A giant bandgap reduction in layered GaTe is demonstrated. Chemisorption of oxygen to the Te-terminated surfaces produces significant restructuring of the conduction band resulting in a bandgap below 0.8 eV, compared to 1.65 eV for pristine GaTe. Localized partial recovery of the pristine gap is achieved by thermal annealing, demonstrating that reversible band engineering in layered semiconductors is accessible through their surfaces.

  8. Engineering the Photonic Density of States with metamaterials

    CERN Document Server

    Jacob*, Z; Naik, G V; Boltasseva, A; Shalaev, E Narimanov V M

    2010-01-01

    The photonic density of states (PDOS), like its' electronic coun- terpart, is one of the key physical quantities governing a variety of phenom- ena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial based PDOS engineering.

  9. Photon management with index-near-zero materials

    Science.gov (United States)

    Wang, Zhu; Wang, Ziyu; Yu, Zongfu

    2016-08-01

    Index-near-zero materials can be used for effective photon management. They help to restrict the angle of acceptance, resulting in greatly enhanced light trapping limit. In addition, these materials also decrease the radiative recombination, leading to enhanced open circuit voltage and energy efficiency in direct bandgap solar cells.

  10. Next Generation Solar Cells Based on Graded Bandgap Device Structures Utilising Rod-Type Nano-Materials

    Directory of Open Access Journals (Sweden)

    Imyhamy M. Dharmadasa

    2015-06-01

    Full Text Available Current solar cells under research and development utilise mainly one absorber layer limiting the photon harvesting capabilities. In order to develop next generation solar cells, research should move towards effective photon harvesting methods utilising low-cost solar energy materials. This will lead to reduce the $W−1 figure for direct solar energy conversion to electrical energy. In this work, a graded bandgap solar cell has been designed to absorb all photons from the UV, visible and IR regions. In addition, impurity PV effect and impact ionisation have been incorporated to enhance charge carrier creation within the same device. This new design has been experimentally tested using the most researched MOCVD grown GaAs/AlGaAs system, in order to confirm its validity. Devices with high Voc ~ 1175 mV and the highest possible FF ~ (0.85–0.87 have been produced, increasing the conversion efficiency to ~20% within only two growth runs. These devices were also experimentally tested for the existence of impurity PV effect and impact ionisation. The devices are PV active in complete darkness producing over 800 mV, Voc indicating the harvesting of IR radiation from the surroundings through impurity PV effect. The quantum efficiency measurements show over 140% signal confirming the contribution to PV action from impact ionisation. Since the concept is successfully proven, the low-cost and scalable electrodeposited semiconducting layers are used to produce graded bandgap solar cell structures. The utilisation of nano- and micro-rod type materials in graded bandgap devices are also presented and discussed in this paper. Preliminary work on glass/FTO/n-ZnS/n-CdS/n-CdTe/Au graded bandgap devices show 10%–12% efficient devices indicating extremely high Jsc values ~48 mA·cm−2, showing the high potential of these devices in achieving higher efficiencies. The detailed results on these low-cost and novel graded bandgap devices are presented in a separate

  11. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  12. Linear and Nonlinear Wave Dynamics in Amorphous Photonic Lattices

    Science.gov (United States)

    Rechtsman, Mikael; Szameit, Alexander; Segev, Mordechai

    Conventional intuition in solid-state physics holds that in order for a solid to have an electronic band-gap, it must be periodic, allowing the use of Bloch's theorem. Indeed, the free-electron approximation seems to imply that Bragg scattering in periodic potentials is a necessary condition for the formation of a band-gap. But this is obviously untrue: looking through a window reveals that glassy silica (SiO2), although possessing no order at all, still displays a band-gap spanning the entire photon energy range of visible light, without absorption. Several experimental studies have probed the properties of the band-gap in such "amorphous" electronic systems using spectroscopic techniques [1], time-of-flight measurements [2], and others. With the major progress in photonic crystals [3, 4], it is natural to explore amorphous photonic structures with band-gaps, where the actual wavefunction can be observed directly, and hence, many physical issues can be studied at an unprecedented level. Indeed, amorphous photonic media have been studied theoretically in several pioneering papers (e.g., [5, 6]), and experiments in the microwave regime have demonstrated the existence of a band-gap [5]. However, amorphous band-gap media have never been studied experimentally in the optical regime. Particularly in optics, the full beauty of disorder can be revealed: optics offers the possibility to precisely engineer the potential strength and period, as well as the unique opportunity to employ nonlinearity under controlled conditions, which could unravel unknown features that are much harder to access experimentally in other systems. Here, we present the first experimental study of amorphous photonic lattices: a two-dimensional array of randomly organized evanescently coupled waveguides. We demonstrate that the bands in this medium, comprising inherently localized Anderson states, are separated by gaps, despite the total lack of Bragg scattering. We find that amorphous photonic

  13. On the Suppression Band and Bandgap of Planar Electromagnetic Bandgap Structures

    Directory of Open Access Journals (Sweden)

    Baharak Mohajer-Iravani

    2014-01-01

    Full Text Available Electromagnetic bandgap structures are considered a viable solution for the problem of switching noise in printed circuit boards and packages. Less attention, however, has been given to whether or not the introduction of EBGs affects the EMI potential of the circuit to couple unwanted energy to neighboring layers or interconnects. In this paper, we show that the bandgap of EBG structures, as generated using the Brillouin diagram, does not necessarily correspond to the suppression bandwidth typically generated using S-parameters. We show that the reactive near fields radiating from openings within the EBG layers can be substantial and are present in the entire frequency band including propagating and nonpropagating mode regions. These fields decay fast with distance; however, they can couple significant energy to adjacent layers and to signal lines. The findings are validated using full-wave three-dimensional numerical simulation. Based on this work, design guidelines for EBG structures can be drawn to insure not only suppression of switching noise but also minimization of EMI and insuring signal integrity.

  14. Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres.

    Science.gov (United States)

    Zhu, Yong-zheng; Cao, Yan-ling; Li, Zhi-hui; Ding, Juan; Liu, Jun-song; Chi, Yuan-bin

    2007-02-01

    With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy.

  15. Research and Applications of All-Solid-State Blue Lasers%全固体蓝激光器的研究与应用

    Institute of Scientific and Technical Information of China (English)

    Tan Huiming

    2004-01-01

    In comparison with traditional gas lasers and lamp pumped solid state lasers, laser diode(LD) pumped or laser diode array (LDA) pumped solid state lasers called all-solid-state lasers are developed quickly in recent years. With the advantages of compact size, long lifetime,

  16. Study on the propagation mechanism of evanescent waves in one-dimensional periodic photonic crystal

    International Nuclear Information System (INIS)

    Based on the evanescent waves theory, the formation condition and propagation mechanism of evanescent waves in one-dimensional periodic photonic crystal are studied. When the incident light travels through the periodic photonic crystal at a certain angle, the optical resonance will occur in the optically denser medium, and a unique photonic local feature will occur in photonic bandgap. Furthermore, the influences on transmission performance by the photonic crystal parameters are discussed respectively. The simulation results show that the structure mentioned above can achieve the performance of high transmission and high Q value, which can provide theoretical references for photonic crystal multi-channel filters

  17. Low bandgap semiconducting polymers for polymeric photovoltaics.

    Science.gov (United States)

    Liu, Chang; Wang, Kai; Gong, Xiong; Heeger, Alan J

    2016-08-22

    In order to develop high performance polymer solar cells (PSCs), full exploitation of the sun-irradiation from ultraviolet (UV) to near infrared (NIR) is one of the key factors to ensure high photocurrents and thus high efficiency. In this review, five of the effective design rules for approaching LBG semiconducting polymers with high molar absorptivity, suitable energy levels, high charge carrier mobility and high solubility in organic solvents are overviewed. These design stratagems include fused heterocycles for facilitating π-electron flowing along the polymer backbone, groups/atoms bridging adjacent rings for maintaining a high planarity, introduction of electron-withdrawing units for lowering the bandgap (Eg), donor-acceptor (D-A) copolymerization for narrowing Eg and 2-dimensional conjugation for broadened absorption and enhanced hole mobility. It has been demonstrated that LBG semiconducting polymers based on electron-donor units combined with strong electron-withdrawing units possess excellent electronic and optic properties, emerging as excellent candidates for efficient PSCs. While for ultrasensitive photodetectors (PDs), which have intensive applications in both scientific and industrial sectors, sensing from the UV to the NIR region is of critical importance. For polymer PDs, Eg as low as 0.8 eV has been obtained through a rational design stratagem, covering a broad wavelength range from the UV to the NIR region (1450 nm). However, the response time of the polymer PDs are severely limited by the hole mobility of LBG semiconducting polymers, which is significantly lower than those of the inorganic materials. Thus, further advancing the hole mobility of LBG semiconducting polymers is of equal importance as broadening the spectral response for approaching uncooled ultrasensitive broadband polymer PDs in the future study. PMID:26548402

  18. Low bandgap semiconducting polymers for polymeric photovoltaics.

    Science.gov (United States)

    Liu, Chang; Wang, Kai; Gong, Xiong; Heeger, Alan J

    2016-08-22

    In order to develop high performance polymer solar cells (PSCs), full exploitation of the sun-irradiation from ultraviolet (UV) to near infrared (NIR) is one of the key factors to ensure high photocurrents and thus high efficiency. In this review, five of the effective design rules for approaching LBG semiconducting polymers with high molar absorptivity, suitable energy levels, high charge carrier mobility and high solubility in organic solvents are overviewed. These design stratagems include fused heterocycles for facilitating π-electron flowing along the polymer backbone, groups/atoms bridging adjacent rings for maintaining a high planarity, introduction of electron-withdrawing units for lowering the bandgap (Eg), donor-acceptor (D-A) copolymerization for narrowing Eg and 2-dimensional conjugation for broadened absorption and enhanced hole mobility. It has been demonstrated that LBG semiconducting polymers based on electron-donor units combined with strong electron-withdrawing units possess excellent electronic and optic properties, emerging as excellent candidates for efficient PSCs. While for ultrasensitive photodetectors (PDs), which have intensive applications in both scientific and industrial sectors, sensing from the UV to the NIR region is of critical importance. For polymer PDs, Eg as low as 0.8 eV has been obtained through a rational design stratagem, covering a broad wavelength range from the UV to the NIR region (1450 nm). However, the response time of the polymer PDs are severely limited by the hole mobility of LBG semiconducting polymers, which is significantly lower than those of the inorganic materials. Thus, further advancing the hole mobility of LBG semiconducting polymers is of equal importance as broadening the spectral response for approaching uncooled ultrasensitive broadband polymer PDs in the future study.

  19. Controlled excitation of electromagnetic band-gap line and point defect modes at microwave frequencies

    Science.gov (United States)

    Schuster, M.; Klein, N.

    2003-03-01

    We report on the controlled excitation of line and point defect modes in a two-dimensional hexagonal electromagnetic band-gap structure made of rods of dielectric material (aluminium oxide). We compared simulation performed with a numerical field simulation software and experimental measurements at microwave frequencies with regard to coupling from external waveguides to line defects and subsequent coupling to resonant modes. We observed that for a line defect in the photonic crystal the impedance matching to a waveguide is strongly dependent on the defect width. We furthermore demonstrated that the coupling to a localized defect resonance can be strongly influenced by the variation of certain single lattice elements, affecting transmission behavior and quality factor of the resonant modes.

  20. Quantum well effect based on hybridization bandgap in deep subwavelength coupled meta-atoms

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongqiang; Li, Yunhui, E-mail: liyunhui@tongji.edu.cn; Wu, Qian; Jiang, Haitao; Zhang, Yewen; Chen, Hong

    2015-09-01

    In this paper, quantum well (QW) effect in a hybridization bandgap (HBG) structure via hiring deep subwavelength coupled meta-atoms is investigated. Subwavelength zero-index-metamaterial-based resonators acting as meta-atoms are side-coupled to a microstrip, forming the HBG structure. Both numerical and microwave experimental results confirm that, through properly hiring another set of meta-atoms, band mismatch between two HBGs can be introduced resulting in the HBG QW effect. Compared with the conventional QW structure based on Bragg interferences in photonic crystal, the device length of the proposed HBG QW structure can be reduced to only 1/4, demonstrating well the deep subwavelength property. Therefore, the above features make our design of HBG QW structures suitable to be utilized as multi-channel filters or multiplexers in microwave and optical communication system.

  1. Photonic crystals with topological defects

    CERN Document Server

    Liew, Seng Fatt; Xiong, Wen; Cao, Hui

    2014-01-01

    We introduce topological defect to a square lattice of elliptical cylinders. Despite the broken translational symmetry, the long-range positional order of the cylinders leads to residual photonic bandgap in the density of optical states. However, the band-edge modes are strongly modified by the spatial variation of ellipse orientation. The $\\Gamma-X$ band-edge mode splits into four regions of high intensity and the output flux becomes asymmetric due to the formation of crystalline domains with different orientation. The $\\Gamma-M$ band-edge mode has the energy flux circulates around the topological defect center, creating an optical vortex. By removing the elliptical cylinders at the center, we create localized defect states which are dominated by either clockwise or counter-clockwise circulating waves. The flow direction can be switched by changing the ellipse orientation. The deterministic aperiodic variation of the unit cell orientation adds another dimension to the control of light in photonic crystals, e...

  2. Photon upconversion with directed emission

    Science.gov (United States)

    Börjesson, K.; Rudquist, P.; Gray, V.; Moth-Poulsen, K.

    2016-08-01

    Photon upconversion has the potential to increase the efficiency of single bandgap solar cells beyond the Shockley Queisser limit. Efficient light management is an important point in this context. Here we demonstrate that the direction of upconverted emission can be controlled in a reversible way, by embedding anthracene derivatives together with palladium porphyrin in a liquid crystalline matrix. The system is employed in a triplet-triplet annihilation photon upconversion scheme demonstrating controlled switching of directional anti Stokes emission. Using this approach an emission ratio of 0.37 between the axial and longitudinal emission directions and a directivity of 1.52 is achieved, reasonably close to the theoretical maximal value of 2 obtained from a perfectly oriented sample. The system can be switched for multiple cycles without any visible degradation and the speed of switching is only limited by the intrinsic rate of alignment of the liquid crystalline matrix.

  3. The role of spin exchange in charge transfer in low-bandgap polymer: Fullerene bulk heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Krinichnyi, V. I., E-mail: kivirus@gmail.com; Yudanova, E. I.; Denisov, N. N. [Kinetics and Catalysis, Institute of Problems of Chemical Physics, Chernogolovka 142432 (Russian Federation)

    2014-07-28

    Formation, relaxation and dynamics of polarons and methanofullerene anion radicals photoinitiated in poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′-benzothiadiazole)]:-[6,6]-phenyl-C{sub 61}-butyric acid methyl ester (PCDTBT:PC{sub 61}BM) bulk heterojunctions were studied mainly by light-induced EPR (LEPR) spectroscopy in wide photon energy and temperature ranges. Some polarons are pinned by spin traps whose number and depth are governed by the composite morphology and photon energy. The proximity of the photon energy and the polymer bandgap reduces the number of such traps, inhibits recombination of mobile charge carriers, and facilitates their mobility in polymer network. Spin relaxation and charge carrier dynamics were studied by the steady-state saturation method at wide range of temperature and photon energy. These processes were shown to be governed by spin exchange as well as by the photon energy. Charge transfer in the composite is governed by the polaron scattering on the lattice phonons of crystalline domains embedded into amorphous polymer matrix and its activation hopping between polymer layers. The energy barrier required for polaron interchain hopping exceeds that of its intrachain diffusion. Anisotropy of polaron dynamics in the PCDTBT:PC61BM composite is less than that of poly(3-alkylthiophenes)-based systems that evidences for better ordering of the former. Lorentzian shape of LEPR lines of both charge carriers, lower concentration of spin traps as well as behaviours of the main magnetic resonance parameters were explained by layer ordered morphology of polymer matrix.

  4. Fabrication of All-Solid-State Lithium-ion Cells using Three-Dimensionally Structured Solid Electrolyte Li7La3Zr2O12 Pellets

    Directory of Open Access Journals (Sweden)

    MAO SHOJI

    2016-08-01

    Full Text Available All-solid-state lithium-ion batteries using Li+-ion conducting ceramic electrolytes have been focused on as attractive future batteries for electric vehicles and renewable energy conversion systems because high safety can be realized due to non-flammability of ceramic electrolytes. In addition, a higher volumetric energy density than that of current lithium-ion batteries is expected since the all-solid-state lithium-ion batteries can be made in bipolar cell configurations. However, the special ideas and techniques based on ceramic processing are required to construct the electrochemical interface for all-solid-state lithium-ion batteries since the battery development has been done so far based on liquid electrolyte system over 100 years. As one of promising approaches to develop practical all-solid-state batteries, we have been focusing on three-dimensionally (3D structured cell configurations such as an interdigitated combination of 3D pillars of cathode and anode, which can be realized by using solid electrolyte membranes with hole-array structures. The application of such kinds of 3D structures effectively increases the interface between solid electrode and solid electrolyte per unit volume, lowering the internal resistance of all-solid-state lithium-ion batteries. In this study, Li6.25Al0.25La3Zr2O12 (LLZAl, which is a Al-doped Li7La3Zr2O12 (LLZ with Li+-ion conductivity of ~10–4 S cm–1 at room temperature and high stability against lithium-metal, was used as a solid electrolyte, and its pellets with 700 um depth holes in 700 x 700 um2 area were fabricated to construct 3D-structured all-solid-state batteries with LiCoO2 / LLZAl / lithium-metal configuration. It is expected that the LiCoO2-LLZAl interface is formed by point to point contact even when the LLZAl pellet with 3D hole-array structure is applied. Therefore, the application of mechanically soft Li3BO3 with a low melting point at around 700 °C was also performed as a supporting

  5. Toward ambient temperature operation with all-solid-state lithium metal batteries with a sp3 boron-based solid single ion conducting polymer electrolyte

    Science.gov (United States)

    Zhang, Yunfeng; Cai, Weiwei; Rohan, Rupesh; Pan, Meize; Liu, Yuan; Liu, Xupo; Li, Cuicui; Sun, Yubao; Cheng, Hansong

    2016-02-01

    The ionic conductivity decay problem of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) when increase the lithium salt of the SPEs up to high concentration is here functionally overcome by the incorporation of a charge delocalized sp3 boron based single ion conducting polymer electrolyte (SIPE) with poly(ethylene oxide) to fabricate solid-state sp3 boron based SIPE membranes (S-BSMs). By characterizations, particularly differential scanning calorimeter (DSC) and ionic conductivity studies, the fabricated S-BSMs showed decreased melting points and increased ionic conductivity as steadily increase the content of sp3 boron based SIPE, which significantly improved the low temperature performance of the all-solid-state lithium batteries. The fabricated Li | S-BSMs | LiFePO4 cells exhibit highly electrochemical stability and excellent cycling at temperature below melting point of PEO, which has never been reported so far for SIPEs based all-solid-state lithium batteries.

  6. All-Solid-Thin Film Electrochromic Devices Consisting of Layers ITO / NiO / ZrO2 / WO3 / ITO

    Directory of Open Access Journals (Sweden)

    K.J. Patel

    2013-05-01

    Full Text Available We have prepared an all-solid-thin film electrochromic device (ECD, consisting of layers ITO / NiO / ZrO2 / WO3 / ITO using the PVD method. The WO3 is used as an electrochromic layer, NiO as an ion-storage layer, and ZrO2 as a solid electrolyte layer in the all-solid-thin film ECD. The optical transmittance varied between 3-59 %. The device shows the coloration and bleaching time of 120 s and 2 s, respectively, with a good memory effect and desirable cycle-life.

  7. Preparation of hydroxide ion conductive KOH–layered double hydroxide electrolytes for an all-solid-state iron–air secondary battery

    Directory of Open Access Journals (Sweden)

    Taku Tsuneishi

    2014-06-01

    Full Text Available Anion conductive solid electrolytes based on Mg–Al layered double hydroxide (LDH were prepared for application in an all-solid-state Fe–air battery. The ionic conductivity and the conducting ion species were evaluated from impedance and electromotive force measurements. The ion conductivity of LDH was markedly enhanced upon addition of KOH. The electromotive force in a water vapor concentration cell was similar to that of an anion-conducting polymer membrane. The KOH–LDH obtained was used as a hydroxide ion conductive electrolyte for all-solid-state Fe–air batteries. The cell performance of the Fe–air batteries was examined using a mixture of KOH–LDH and iron-oxide-supported carbon as the negative electrode.

  8. Fabrication of photonic amorphous diamonds for terahertz-wave applications

    Science.gov (United States)

    Komiyama, Yuichiro; Abe, Hiroyuki; Kamimura, Yasushi; Edagawa, Keiichi

    2016-05-01

    A recently proposed photonic bandgap material, named "photonic amorphous diamond" (PAD), was fabricated in a terahertz regime, and its terahertz-wave propagation properties were investigated. The PAD structure was fabricated from acrylic resin mixed with alumina powder, using laser lithographic, micro-additive manufacturing technique. After fabrication, the resulting structure was dewaxed and sintered. The formation of a photonic bandgap at around 0.45 THz was demonstrated by terahertz time-domain spectroscopy. Reflecting the disordered nature of the random network structure, diffusive terahertz-wave propagation was observed in the passbands; the scattering mean-free path decreased as the frequency approached the band edge. The mean-free paths evaluated at the band edges were close to the Ioffe-Regel threshold value for wave localization.

  9. An Integrated Glucose Sensor with an All-Solid-State Sodium Ion-Selective Electrode for a Minimally Invasive Glucose Monitoring System

    OpenAIRE

    Junko Kojima; Samiko Hosoya; Chihiro Suminaka; Nobuyasu Hori; Toshiyuki Sato

    2015-01-01

    We developed a minimally invasive glucose monitoring system that uses a microneedle to permeate the skin surface and a small hydrogel to accumulate interstitial fluid glucose. The measurement of glucose and sodium ion levels in the hydrogel is required for estimating glucose levels in blood; therefore, we developed a small, enzyme-fixed glucose sensor with a high-selectivity, all-solid-state, sodium ion-selective electrode (ISE) integrated into its design. The glucose sensor immobilized gluco...

  10. NiCo2O4@TiN Core-shell Electrodes through Conformal Atomic Layer Deposition for All-solid-state Supercapacitors

    KAUST Repository

    Wang, Ruiqi

    2016-03-04

    Ternary transition metal oxides such as NiCo2O4 show great promise as supercapacitor electrode materials. However, the unsatisfactory rate performance of NiCo2O4 may prove to be a major hurdle to its commercial usage. Herein, we report the development of NiCo2O4@TiN core–shell nanostructures for all-solid-state supercapacitors with significantly enhanced rate capability. We demonstrate that a thin layer of TiN conformally grown by atomic layer deposition (ALD) on NiCo2O4 nanofiber arrays plays a key role in improving their electrical conductivity, mechanical stability, and rate performance. Fabricated using the hybrid NiCo2O4@TiN electrodes, the symmetric all-solid-state supercapacitor exhibited an impressive stack power density of 58.205 mW cm−3 at a stack energy density of 0.061 mWh cm−3. To the best of our knowledge, these values are the highest of any NiCo2O4-based all-solid-state supercapacitor reported. Additionally, the resulting NiCo2O4@TiN all-solid-state device displayed outstanding cycling stability by retaining 70% of its original capacitance after 20,000 cycles at a high current density of 10 mA cm−2. These results illustrate the promise of ALD-assisted hybrid NiCo2O4@TiN electrodes for sustainable and integrated energy storage applications.

  11. Preparation of hydroxide ion conductive KOH–layered double hydroxide electrolytes for an all-solid-state iron–air secondary battery

    OpenAIRE

    Taku Tsuneishi; Hisatoshi Sakamoto; Kazushi Hayashi; Go Kawamura; Hiroyuki Muto; Atsunori Matsuda

    2014-01-01

    Anion conductive solid electrolytes based on Mg–Al layered double hydroxide (LDH) were prepared for application in an all-solid-state Fe–air battery. The ionic conductivity and the conducting ion species were evaluated from impedance and electromotive force measurements. The ion conductivity of LDH was markedly enhanced upon addition of KOH. The electromotive force in a water vapor concentration cell was similar to that of an anion-conducting polymer membrane. The KOH–LDH obtained was used as...

  12. Bandgap calculations and trends of organometal halide perovskites

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; García Lastra, Juan Maria; Thygesen, Kristian Sommer;

    2014-01-01

    Energy production from the Sun requires a stable efficient light absorber. Promising candidates in this respect are organometal perovskites (ABX3), which have been intensely investigated during the last years. Here, we have performed electronic structure calculations of 240 perovskites composed...... of Cs, CH3NH3, and HC(NH2)2 as A-cation, Sn and Pb as B-ion, and a combination of Cl, Br, and I as anions. The calculated gaps span over a region from 0.5 to 5.0 eV. In addition, the trends over bandgaps have been investigated: the bandgap increases with an increase of the electronegativities...

  13. Optimum design of band-gap beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    of a single, linearly elastic material without damping. Numerical results are presented for different combinations of classical boundary conditions, prescribed orders of the upper and lower natural frequencies of maximized natural frequency gaps, and a given minimum constraint value for the beam cross......The design of band-gap structures receives increasing attention for many applications in mitigation of undesirable vibration and noise emission levels. A band-gap structure usually consists of a periodic distribution of elastic materials or segments, where the propagation of waves is impeded...

  14. All-solid-state electrochemical capacitors using MnO2 electrode/SiO2-Nafion electrolyte composite prepared by the sol-gel process

    Science.gov (United States)

    Shimamoto, Kazushi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

    2014-02-01

    Electrode-electrolyte composites of MnO2 active material, acetylene black (AB), and SiO2-Nafion solid electrolyte were prepared using the sol-gel process to form good solid-solid interfaces. The composites were obtained by the addition of MnO2 and AB into a sol of hydrolyzed tetraethoxysilane with Nafion, and successive solidification of the precursor sol. Scanning electron microscope and energy dispersive X-ray spectroscopy measurements show that good solid-solid interface is formed between electrodes and solid electrolytes in the composites. All-solid-state hybrid capacitors were fabricated using the composites or the hand-grinding mixture of MnO2, AB and SiO2-Nafion powder as positive electrodes, activated carbon powder as a negative electrode, and phosphosilicate gel as a solid electrolyte. The all-solid-state hybrid capacitors using the composites exhibit larger capacitances and better rate performance than the capacitors using the electrode prepared by hand-mixing of powders. Specific discharge capacitances of the capacitor with the composite are 85 F g-1 for the one with the composite electrode and 48 F g-1 for the one with the hand-mixed electrode, at 1 mA cm-2. Moreover, the all-solid-state capacitors using the composite electrode can be operated at temperatures between -30 °C and 60 °C.

  15. Room-Temperature All-solid-state Rechargeable Sodium-ion Batteries with a Cl-doped Na3PS4 Superionic Conductor.

    Science.gov (United States)

    Chu, Iek-Heng; Kompella, Christopher S; Nguyen, Han; Zhu, Zhuoying; Hy, Sunny; Deng, Zhi; Meng, Ying Shirley; Ong, Shyue Ping

    2016-09-20

    All-solid-state sodium-ion batteries are promising candidates for large-scale energy storage applications. The key enabler for an all-solid-state architecture is a sodium solid electrolyte that exhibits high Na(+) conductivity at ambient temperatures, as well as excellent phase and electrochemical stability. In this work, we present a first-principles-guided discovery and synthesis of a novel Cl-doped tetragonal Na3PS4 (t-Na3-xPS4-xClx) solid electrolyte with a room-temperature Na(+) conductivity exceeding 1 mS cm(-1). We demonstrate that an all-solid-state TiS2/t-Na3-xPS4-xClx/Na cell utilizing this solid electrolyte can be cycled at room-temperature at a rate of C/10 with a capacity of about 80 mAh g(-1) over 10 cycles. We provide evidence from density functional theory calculations that this excellent electrochemical performance is not only due to the high Na(+) conductivity of the solid electrolyte, but also due to the effect that "salting" Na3PS4 has on the formation of an electronically insulating, ionically conducting solid electrolyte interphase.

  16. Comparison between all-solid-state Raman lasers and OPO lasers%固体Raman激光器与OPO激光器比较

    Institute of Scientific and Technical Information of China (English)

    孙国正

    2011-01-01

    The development of all-solid-state Raman laser and optical parametric oscillation (OPO) laser were summarized during the past five years.The principle and crystal of Raman laser and OPO laser were compared.An all-solid-state Raman lasers has advantages in beam quality and optical stability.While, an OPO laser has a larger tuning range and higher output power.Finally, the future development of all-solid-state Raman and OPO lasers was put forward.%综述了近5年来固体Raman激光器和光参量振荡(OPO)激光器的发展情况,并对Raman激光器和OPO激光器在工作原理、晶体材料方面进行了比较.Raman激光器在光束质量、光路稳定方面存在优势,而OPO激光器调谐范围大,输出功率高.最后对固体Raman激光器和OPO激光器发展前景进行了简要介绍.

  17. Microwave Photonics

    OpenAIRE

    A J Seeds; Liu, C. P.; Ismail, T; Fice, M. J.; Pozzi, F.; Steed, R. J.; Rouvalis, E.; Renaud, C.C.

    2010-01-01

    Microwave photonics is the use of photonic techniques for the generation, transmission, processing and reception of signals having spectral components at microwave frequencies. This tutorial reviews the technologies used and gives applications examples.

  18. Fabrication of a Two-Dimensional Organic Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-Yong; LI Yan; GONG Qi-Huang; CHENG Bing-Ying; ZHANG Dao-Zhong

    2005-01-01

    @@ A high-quality two-dimensional polystyrene photonic crystal is fabricated by the method of focused ion beam etching. The scanning electron microscopy (SEM) and the transmittance spectrum are used to characterize the properties of the photonic crystal. The measured transmittance spectrum is in agreement with the theoretical one. The influences of the disorders caused by the random perturbations in the diameter or the position of the air holes on the photonic band structure are analysed. It is found that the phtonic bandgap can tolerate less than 10% degree of disorder.

  19. III-V/Si photonics by die-to-wafer bonding

    Directory of Open Access Journals (Sweden)

    G. Roelkens

    2007-07-01

    Full Text Available Photonic integrated circuits offer the potential of realizing low-cost, compact optical functions. Silicon-on-insulator (SOI is a promising material platform for this photonic integration, as one can rely on the massive electronics processing infrastructure to process the optical components. However, the integration of a Si laser is hampered by its indirect bandgap. Here, we present the integration of a direct bandgap III-V epitaxial layer on top of the SOI waveguide layer by means of a die-to-wafer bonding process in order to realize near-infrared laser emission on and coupled to SOI.

  20. Photon Structure

    OpenAIRE

    Grindhammer, Guenter

    2001-01-01

    Large pT processes at HERA, initiated by almost real and by virtual photons, provide information on the structure of the photon. We report on the latest measurements of dijets and large pT particle production with the H1 detector. This includes a leading order determination of an effective virtual photon parton density, of the gluon density of the photon, and comparisons with models.

  1. Controlling Interface States in 1D Photonic Crystals by tuning Bulk Geometric Phases

    CERN Document Server

    Gao, Wensheng; Chen, Baojie; Pun, Edwin Y B; Chan, C T; Tam, Wing Yim

    2016-01-01

    Interface states in photonic crystals usually require defects or surface/interface decorations. We show here that one can control interface states in 1D photonic crystals through the engineering of geometrical phase such that interface states can be guaranteed in even or odd, or in all photonic bandgaps. We verify experimentally the designed interface states in 1D multilayered photonic crystals fabricated by electron beam vapor deposition. We also obtain the geometrical phases by measuring the reflection phases at the bandgaps of the PCs and achieve good agreement with the theory. Our approach could provide a platform for the design of using interface states in photonic crystals for nonlinear optic, sensing, and lasing applications

  2. CMOS bandgap references and temperature sensors and their applications

    NARCIS (Netherlands)

    Wang, G.

    2005-01-01

    Two main parts have been presented in this thesis: device characterization and circuit. In integrated bandgap references and temperature sensors, the IC(VBE, characteristics of bipolar transistors are used to generate the basic signals with high accuracy. To investigate the possibilities to fabrica

  3. Bandgap Opening in Graphene Induced by Patterned Hydrogen Adsorption

    DEFF Research Database (Denmark)

    Balog, Richard; Jørgensen, Bjarke; Nilsson, Louis;

    2010-01-01

    fermions, and graphene shows ballistic charge transport, turning it into an ideal material for circuit fabrication. However, graphene lacks a bandgap around the Fermi level, which is the defining concept for semiconductor materials and essential for controlling the conductivity by electronic means. Theory...

  4. Design for maximum band-gaps in beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    This paper aims to extend earlier optimum design results for transversely vibrating Bernoulli-Euler beams by determining new optimum band-gap beam structures for (i) different combinations of classical boundary conditions, (ii) much larger values of the orders n and n-1 of adjacent upper and lower...

  5. Extended-Range Ultrarefractive 1D Photonic Crystal Prisms

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    A proposal has been made to exploit the special wavelength-dispersive characteristics of devices of the type described in One-Dimensional Photonic Crystal Superprisms (NPO-30232) NASA Tech Briefs, Vol. 29, No. 4 (April 2005), page 10a. A photonic crystal is an optical component that has a periodic structure comprising two dielectric materials with high dielectric contrast (e.g., a semiconductor and air), with geometrical feature sizes comparable to or smaller than light wavelengths of interest. Experimental superprisms have been realized as photonic crystals having three-dimensional (3D) structures comprising regions of amorphous Si alternating with regions of SiO2, fabricated in a complex process that included sputtering. A photonic crystal of the type to be exploited according to the present proposal is said to be one-dimensional (1D) because its contrasting dielectric materials would be stacked in parallel planar layers; in other words, there would be spatial periodicity in one dimension only. The processes of designing and fabricating 1D photonic crystal superprisms would be simpler and, hence, would cost less than do those for 3D photonic crystal superprisms. As in 3D structures, 1D photonic crystals may be used in applications such as wavelength-division multiplexing. In the extended-range configuration, it is also suitable for spectrometry applications. As an engineered structure or artificially engineered material, a photonic crystal can exhibit optical properties not commonly found in natural substances. Prior research had revealed several classes of photonic crystal structures for which the propagation of electromagnetic radiation is forbidden in certain frequency ranges, denoted photonic bandgaps. It had also been found that in narrow frequency bands just outside the photonic bandgaps, the angular wavelength dispersion of electromagnetic waves propagating in photonic crystal superprisms is much stronger than is the angular wavelength dispersion obtained

  6. Polychromatic photons

    DEFF Research Database (Denmark)

    Keller, Ole

    2002-01-01

    A review is given of the space-time wave mechanics of single photons, a subject with an almost century long history. The Landau-Peierls photon wave function, which is related nonlocally to the electromagnetic field is first described, and thereafter the so-called energy wave function, based...... train quantum electrodynamics. A brief description of particle (photon) position operators is given, and it is shown that photons usually are only algebraically confined in an emission process. Finally, it is demonstrated that the profile of the birth domain of a radio-frequency photon emitted...

  7. Very Small Bandgap π-Conjugated Polymers with Extended Thienoquinoids.

    Science.gov (United States)

    Kawabata, Kohsuke; Saito, Masahiko; Osaka, Itaru; Takimiya, Kazuo

    2016-06-22

    The introduction of quinoidal character to π-conjugated polymers is one of the effective approaches to reducing the bandgap. Here we synthesized new π-conjugated polymers (PBTD4T and PBDTD4T) incorporating thienoquinoids 2,2'-bithiophene-5,5'-dione (BTD) and benzo[1,2-b:4,5-b']dithiophene-2,6-dione (BDTD) as strong electron-deficient (acceptor) units. PBTD4T showed a deep LUMO energy level of -3.77 eV and a small bandgap of 1.28 eV, which are similar to those of the analog using thieno[3,2-b]thiophene-2,5-dione (TTD) (PTTD4T). PBDTD4T had a much deeper LUMO energy level of -4.04 eV and a significantly smaller bandgap of 0.88 eV compared to those of the other two polymers. Interestingly, PBDTD4T showed high transparency in the visible region. The very small bandgap of PBDTD4T can be rationalized by the enhanced contribution of the resonance backbone structure in which the p-benzoquinodimethane skeleton in the BDTD unit plays a crucial role. PBTD4T and PBDTD4T exhibited ambipolar charge transport with more balanced mobilities between the hole and the electron than PTTD4T. We believe that the very small bandgap, i.e., the high near-infrared activity, as well as the well-balanced ambipolar property of the π-conjugated polymers based on these units would be of particular interest in the fabrication of next-generation organic devices.

  8. Optimal design of tunable phononic bandgap plates under equibiaxial stretch

    Science.gov (United States)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, M. S.; Guest, James K.

    2016-05-01

    Design and application of phononic crystal (PhCr) acoustic metamaterials has been a topic with tremendous growth of interest in the last decade due to their promising capabilities to manipulate acoustic and elastodynamic waves. Phononic controllability of waves through a particular PhCr is limited only to the spectrums located within its fixed bandgap frequency. Hence the ability to tune a PhCr is desired to add functionality over its variable bandgap frequency or for switchability. Deformation induced bandgap tunability of elastomeric PhCr solids and plates with prescribed topology have been studied by other researchers. Principally the internal stress state and distorted geometry of a deformed phononic crystal plate (PhP) changes its effective stiffness and leads to deformation induced tunability of resultant modal band structure. Thus the microstructural topology of a PhP can be altered so that specific tunability features are met through prescribed deformation. In the present study novel tunable PhPs of this kind with optimized bandgap efficiency-tunability of guided waves are computationally explored and evaluated. Low loss transmission of guided waves throughout thin walled structures makes them ideal for fabrication of low loss ultrasound devices and structural health monitoring purposes. Various tunability targets are defined to enhance or degrade complete bandgaps of plate waves through macroscopic tensile deformation. Elastomeric hyperelastic material is considered which enables recoverable micromechanical deformation under tuning finite stretch. Phononic tunability through stable deformation of phononic lattice is specifically required and so any topology showing buckling instability under assumed deformation is disregarded. Nondominated sorting genetic algorithm (GA) NSGA-II is adopted for evolutionary multiobjective topology optimization of hypothesized tunable PhP with square symmetric unit-cell and relevant topologies are analyzed through finite

  9. An all-solid state laser system for the laser ion source RILIS and in-source laser spectroscopy of astatine at ISOLDE,CERN

    OpenAIRE

    Rothe, Sebastian

    2012-01-01

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at CERN/ISOLDE by the addition of an all-solid state tunable titanium:sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spec...

  10. Dispersion-shifted all-solid high index-contrast microstructured optical fiber for nonlinear applications at 1.55µm

    OpenAIRE

    Feng, Xian; Poletti, Francesco; Camerlingo, Angela; Parmigiani, Francesca; Horak, Peter; Petropoulos, Periklis; Loh, Wei H.; Richardson, David J

    2009-01-01

    We report the fabrication of an all-solid highly nonlinear microstructured optical fiber. The structured preform was made by glass extrusion using two types of commercial lead silicate glasses that provide high index-contrast. Effectively single-moded guidance was observed in the fiber at 1.55µm. The effective nonlinearity and the propagation loss at this wavelength were measured to be 120W/km respectively at 1.55µm. These predictions are consistent with the experimentally determined dispersi...

  11. High-efficiency GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy

    OpenAIRE

    Lu, Shulong; Ji, Lian; He, Wei; Dai, Pan; Yang, Hui; Arimochi, Masayuki; Yoshida, Hiroshi; Uchida, Shiro; Ikeda, Masao

    2011-01-01

    We report the initial results of GaAs and GaInP solar cells grown by all solid-state molecular-beam-epitaxy (MBE) technique. For GaAs single-junction solar cell, with the application of AlInP as the window layer and GaInP as the back surface field layer, the photovoltaic conversion efficiency of 26% at one sun concentration and air mass 1.5 global (AM1.5G) is realized. The efficiency of 16.4% is also reached for GaInP solar cell. Our results demonstrate that the MBE-grown phosphide-contained ...

  12. Facile template-free synthesis of vertically aligned polypyrrole nanosheets on nickel foams for flexible all-solid-state asymmetric supercapacitors

    Science.gov (United States)

    Yang, Xiangwen; Lin, Zhixing; Zheng, Jingxu; Huang, Yingjuan; Chen, Bin; Mai, Yiyong; Feng, Xinliang

    2016-04-01

    This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol-water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode-electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg-1 and a high power density of 6.2 kW kg-1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window.This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol-water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode-electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg-1 and a high power density of 6.2 kW kg-1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window. Electronic supplementary information (ESI) available: ESI

  13. A photonic thermalization gap in disordered lattices

    CERN Document Server

    Kondakci, H E; Saleh, B E A

    2016-01-01

    The formation of gaps -- forbidden ranges in the values of a physical parameter -- is a ubiquitous feature of a variety of physical systems: from energy bandgaps of electrons in periodic lattices and their analogs in photonic, phononic, and plasmonic systems to pseudo energy gaps in aperiodic quasicrystals. Here, we report on a `thermalization' gap for light propagating in finite disordered structures characterized by disorder-immune chiral symmetry -- the appearance of the eigenvalues and eigenvectors in skew-symmetric pairs. In this class of systems, the span of sub- thermal photon statistics is inaccessible to input coherent light, which -- once the steady state is reached -- always emerges with super-thermal statistics no matter how small the disorder level. We formulate an independent constraint that must be satisfied by the input field for the chiral symmetry to be `activated' and the gap to be observed. This unique feature enables a new form of photon-statistics interferometry: the deterministic tuning...

  14. Facile fabrication of all-solid-state flexible interdigitated MnO2 supercapacitor via in-situ catalytic solution route

    Science.gov (United States)

    Long, Xiao; Zeng, Zhigang; Guo, Erjuan; Shi, Xiaobo; Zhou, Haijun; Wang, Xiaohong

    2016-09-01

    With the rapid development of wearable and portable electronics, the demand for all-solid-state flexible energy storage devices with high performance, long-term cycling stability and bending stability has been aroused. Physical and chemical method for preparing thin-film materials has enabled planar flexible supercapacitors (SCs) to be fabricated for a variety of applications. In this work, we report on the facile fabrication of an all-solid-state flexible interdigitated supercapacitor with a convenient and efficient two-step method. 3-D nanostructured α-MnO2 has been prepared on the surface of interdigitated Pt metal pattern on polyethylene terephthalate (PET) substrate as high-performance electrode material via in-situ catalytic solution route without any assistance of template or surfactant. The SCs are fabricated with PVA/H3PO4 as solid-state electrolyte, which exhibited good electrochemical performance with areal capacitance as much as 20 mF cm-2 at a scan rate of 10 mV s-1, relatively high energy density (3.6 × 10-7 Wh cm-2-1.9 × 10-6 Wh cm-2) and power density (9 × 10-5 W cm-2-1.6 × 10-4 W cm-2), and excellent long-term cycling stability with capacitance retention of 82.2% (10,000 times charge and discharge), and bending stability with capacitance retention of 89.6%.

  15. Wet-process Fabrication of Low-cost All-solid Wire-shaped Solar Cells on Manganese-plated Electrodes

    International Nuclear Information System (INIS)

    Highlights: • All-solid wire-shaped flexible solar cells are firstly assembled on low-cost Mn-plated fibers. • Energy efficiency improved by >27% after coating a layer of Mn on various substrates. • The cell is fabricated via wet process under low temperature and mild pH conditions. • Stable flexible solar cells are realized on lightweight and low-cost polymer fiber. - Abstract: All-solid wire-shaped flexible solar cells are assembled for the first time on low-cost Mn-plated wires through wet-process fabrication under low temperature and mild pH conditions. With a price cheap as the steel, metal Mn can be easily plated on almost any substrates, and evidently promote the photovoltaic efficiency of wire-shaped solar cells on various traditional metal wire substrates, such as Fe and Ti, by 27% and 65%, respectively. Flexible solar cell with much lower cost and weight is assembled on Mn-plated polymer substrate, and is still capable of giving better performance than that on Fe or Ti substrate. Both its mechanical and chemical stability are good for future weaving applications. Owing to the wire-type structure, such low-cost metals as Mn, which are traditionally regarded as unsuitable for solar cells, may provide new opportunities for highly efficient solar cells

  16. Photonic Lantern

    CERN Document Server

    Leon-Saval, Sergio; Bland-Hawthorn, Joss

    2015-01-01

    Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus, enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail.

  17. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  18. Experimental realization of microwave photonic topological insulators

    Science.gov (United States)

    Dong, Jianwen

    2015-03-01

    Topological properties play a fundamental role in many physical phenomena. While topology focus on electronic systems, there has been a recent emergence of interest in exploring topological orders with photons. Recent experiments have demonstrated substantial progress towards the implementation of Hamiltonians with topological robustness, from microwave to visible frequency domains. Here, we will show the demonstration on nontrivial photonic bandgaps, as well as the topologically protected edge states. We designed and fabricated a metacrystal comprising non-resonant meta-atoms sandwiched between two metallic plates. Spin Chern number of photonic crystals is calculated based on group theory and accurately predicts topological characters of edge states in different gaps. Topologically nontrivial gaps are achieved by mode exchange at high symmetric k-points. Nontrivial bandgap was confirmed by experimentally measured transmission spectra and calculated nonzero spin Chern number. Gapless spin-filtered edge states were demonstrated experimentally by measuring Ez fields and Hz fields, as well as their phase differences. Robustness of the edge states were also observed when an obstacle is introduced near the edge.

  19. Controlling spontaneous emission of light by photonic crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2005-01-01

    Photonic bandgap crystals were proposed almost two decades ago as a unique tool for controlling propagation and emission of light. Since then the research field of photonic crystals has exploded and many beautiful demonstrations of the use of photonic crystals and fibers for molding light...... propagation have appeared that hold great promises for integrated optics. These major achievements solidly demonstrate the ability to control propagation of light. In contrast, an experimental demonstration of the use of photonic crystals for timing the emission of light has so far lacked. In a recent...... publication in Nature, we have demonstrated experimentally that both the direction and time of spontaneous emission can be controlled, thereby confirming the original proposal by Eli Yablonovich that founded the field of photonic crystals. We believe that this work opens new opportunities for solid...

  20. High dno/dT liquid crystals and their applications in a thermally tunable liquid crystal photonic crystal fiber

    DEFF Research Database (Denmark)

    Li, J.; Gauza, S.; Wu, S.-T.;

    2006-01-01

    crystal mixtures, designated as UCF-1 and UCF-2. The dn(o)/dT of UCF-1 is similar to 4x higher than that of 5CB at room temperature. By infiltrating UCF-1 into the air holes of a three-rod core photonic crystal fiber, we demonstrate a thermally tunable photonic bandgap fiber with tuning sensitivity of 27...

  1. Bandgap tunability at single-layer molybdenum disulphide grain boundaries

    KAUST Repository

    Huang, Yu Li

    2015-02-17

    Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85±0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

  2. Structure and optical bandgap relationship of π-conjugated systems.

    Science.gov (United States)

    Botelho, André Leitão; Shin, Yongwoo; Liu, Jiakai; Lin, Xi

    2014-01-01

    In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH) Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any [Formula: see text]-conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination [Formula: see text], a mean error of -0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics.

  3. Structure and optical bandgap relationship of π-conjugated systems.

    Directory of Open Access Journals (Sweden)

    André Leitão Botelho

    Full Text Available In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any [Formula: see text]-conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination [Formula: see text], a mean error of -0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics.

  4. Tunable photonic crystals based on ferroelectric and ferromagnetic materials by focused ion beam

    Institute of Scientific and Technical Information of China (English)

    Ziyou Zhou; Xiaoyue Huang; Raghav Vanga; Rong Li

    2007-01-01

    By making photonic crystals in ferroelectric and ferromagnetic materials, field-provoked tunability of photonic crystals is broadening the interest in new applications of on-chip photonic devices. We report a nano-precise fabrication of various designs of photonic crystals in these non-conventional materials using the focused ion beam milling technique. Standard methods are developed and parameters for different materials are calibrated. Optical responses such as bandgaps and polarization status changing from planar film waveguide system with these patterns have been examined on ferromagnetic materials.

  5. Extreme group index measured and calculated in 2D SOI-based photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Jacobsen, Rune Shim; Fage-Pedersen, Jacob;

    2005-01-01

    lattice of air-holes in the 216-nm thick silicon layer in an SOI material. Experimental transmission spectra show a mode cut-off around 1562.5 nm for the fundamental photonic bandgap mode. In order to measure and model the group index of modes in the PCW, a time-of-flight (ToF) method is applied....

  6. Liquid-infiltrated photonic crystals for lab-on-a-chip applications

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Pedersen, Jesper; Mortensen, Niels Asger

    2007-01-01

    In this paper we theoretically discuss how a strongly dispersive photonic crystals environment may be used to enhance the light-matter interactions, thus potentially compensating for the reduced optical path in typical lab-on- a-chip systems. Combining electromagnetic perturbation theory with full-wave...... electromagnetic simulations we address the prospects for slow-light enhancement of Beer-Lambert absorption and photonic band-gap based refractometry....

  7. Controllable light filters using an all-solid-state switchable mirror with a Mg-Ir thin film for preterm infant incubators

    Science.gov (United States)

    Tajima, Kazuki; Shimoike, Mika; Li, Heng; Inagaki, Masumi; Izumi, Hitomi; Akiyama, Misaki; Matsushima, Yukiko; Ohta, Hidenobu

    2013-04-01

    We have fabricated a controllable light filter using an all-solid-state switchable mirror incorporating a Mg-Ir thin film for use in preterm infant incubators. The solid-state switchable mirror device was fabricated by depositing a multilayer on a glass substrate. The mixed hydride of MgH2 and Mg6Ir2H11 created from the Mg-Ir thin film is red in the transparent state. The optical switching speeds between the reflective and transparent red states depended on applied voltage. The device showed three states, namely, reflective, black, and transparent red, due to the properties of the switchable mirror material. These results suggest that the material could be used as a controllable light filter for preterm infant incubators, since it eliminates the light wavelength that disturbs regular sleep-wake cycles of preterm infants.

  8. A Compact All-Solid-State 630-ps 9.43-kHz High Power Nd: YAG/ Nd: YVO4 Hybrid Laser System

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang; WEI Xiao-Yu; DU Ke-Ming; LI Jing-Zhen

    2008-01-01

    We present a simple and compact design for an all-solid-state laser amplifier system which can output 9.43-kHz 630-ps, 3.5-W pulse trains under 20W absorbed pumping power. The excellent matching between the repetition of its seed source and the fluorescence lifetime of the amplifying medium makes it quiet efficient for the four-pass amplifier to be pumped in cw mode without need of any synchronization device between the oscillator and the amplifier. The entire setup just covers an area of 55×25cm2. The output average power fluctuation is less than ±1.5% within 10min and 3% within 6h.

  9. 1,2,4-Triazolium perfluorobutanesulfonate as an archetypal pure protic organic ionic plastic crystal electrolyte for all-solid-state fuel cells

    DEFF Research Database (Denmark)

    Luo, Jiangshui; Jensen, Annemette Hindhede; Brooks, Neil R.;

    2015-01-01

    1,2,4-Triazolium perfluorobutanesulfonate (1), a novel, pure protic organic ionic plastic crystal (POIPC) with a wide plastic crystalline phase, has been explored as a proof-of-principle anhydrous proton conductor for all-solid-state high temperature hydrogen/air fuel cells. Its physicochemical......), plastic crystalline (phase II and I) and melt phases successively from 173 C to 200 C. Differential scanning calorimetry and temperature dependent powder X-ray diffraction (XRD) measurements together with polarized optical microscopy and thermomechanical analysis reveal the two solid–solid phase...... transitions of 1 at 76.8 C and 87.2 C prior to the melting transition at 180.9 C, showing a wide plastic phase (87–181 C). Scanning electron microscopy displays the morphology of different phases, indicating the plasticity in phase I. Single-crystal XRD studies reveal the molecular structure of 1 and its...

  10. An all-solid state laser system for the laser ion sources RILIS and in-source laser spectroscopy of astatine at ISOLDE/CERN

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Sebastian

    2012-09-24

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at CERN/ISOLDE by the addition of an all-solid state tunable titanium:sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spectroscopy was performed at ISOLDE/CERN and at ISAC/TRIUMF radioactive ion beam facilities to develop an efficient and selective three-colour ionization scheme for the purely radioactive element astatine. A LabVIEW based monitoring, control and measurement system was conceived which enabled, in conjunction with Dual RILIS operation, the spectroscopy of high lying Rydberg states, from which the ionization potential of the astatine atom was determined for the first time experimentally.

  11. An all-solid state laser system for the laser ion sources RILIS and in-source laser spectroscopy of astatine at ISOLDE/CERN

    International Nuclear Information System (INIS)

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at CERN/ISOLDE by the addition of an all-solid state tunable titanium:sapphire (Ti:Sa) laser system to complement the well-established system of dye lasers. Synchronous operation of the so called Dual RILIS system of Ti:Sa and dye lasers was investigated and the potential for increased ion beam intensity, reliability, and reduced setup time has been demonstrated. In-source resonance ionization spectroscopy was performed at ISOLDE/CERN and at ISAC/TRIUMF radioactive ion beam facilities to develop an efficient and selective three-colour ionization scheme for the purely radioactive element astatine. A LabVIEW based monitoring, control and measurement system was conceived which enabled, in conjunction with Dual RILIS operation, the spectroscopy of high lying Rydberg states, from which the ionization potential of the astatine atom was determined for the first time experimentally.

  12. Facile fabrication of all-solid-state SnO2/NiCo2O4 biosensor for self-powered glucose detection

    Science.gov (United States)

    Cai, Bin; Mao, Weiwei; Ye, Zhizhen; Huang, Jingyun

    2016-09-01

    With increasing attention on daily diabetes management, we develop an all-solid-state self-powered glucose biosensor, with simultaneous solar energy conversion, electrochemical energy storage and glucose sensing. The SnO2 nanosheet arrays are used to obtain photogenerated electron-hole pairs, and rhombus-shaped NiCo2O4 nanorod arrays are developed for solar energy storage. A stable open circuit voltage ~0.58 V is obtained after being fully charged, which is a suitable voltage for the oxidation of glucose. The biosensor can work under two different modes without any external bias voltage, and both show large linear range and excellent selectivity. Under the sunlight, photocurrent shows a sensitive decrease upon different glucose additions. Meanwhile, in the dark condition, the open circuit voltage of the charged biosensor also exhibits a corresponding response to glucose.

  13. High-Performance All-Solid-State Lithium-Sulfur Battery Enabled by a Mixed-Conductive Li2S Nanocomposite.

    Science.gov (United States)

    Han, Fudong; Yue, Jie; Fan, Xiulin; Gao, Tao; Luo, Chao; Ma, Zhaohui; Suo, Liumin; Wang, Chunsheng

    2016-07-13

    All-solid-state lithium-sulfur batteries (ASSLSBs) using highly conductive sulfide-based solid electrolytes suffer from low sulfur utilization, poor cycle life, and low rate performance due to the huge volume change of the electrode and the poor electronic and ionic conductivities of S and Li2S. The most promising approach to mitigate these challenges lies in the fabrication of a sulfur nanocomposite electrode consisting of a homogeneous distribution of nanosized active material, solid electrolyte, and carbon. Here, we reported a novel bottom-up method to synthesize such a nanocomposite by dissolving Li2S as the active material, polyvinylpyrrolidone (PVP) as the carbon precursor, and Li6PS5Cl as the solid electrolyte in ethanol, followed by a coprecipitation and high-temperature carbonization process. Li2S active material and Li6PS5Cl solid electrolyte with a particle size of ∼4 nm were uniformly confined in a nanoscale carbon matrix. The homogeneous nanocomposite electrode consisting of different nanoparticles with distinct properties of lithium storage capability, mechanical reinforcement, and ionic and electronic conductivities enabled a mechanical robust and mixed conductive (ionic and electronic conductive) sulfur electrode for ASSLSB. A large reversible capacity of 830 mAh/g (71% utilization of Li2S) at 50 mA/g for 60 cycles with a high rate performance was achieved at room temperature even at a high loading of Li2S (∼3.6 mg/cm(2)). This work provides a new strategy to design a mechanically robust, mixed conductive nanocomposite electrode for high-performance all-solid-state lithium sulfur batteries. PMID:27322663

  14. High-Performance All-Solid-State Lithium-Sulfur Battery Enabled by a Mixed-Conductive Li2S Nanocomposite.

    Science.gov (United States)

    Han, Fudong; Yue, Jie; Fan, Xiulin; Gao, Tao; Luo, Chao; Ma, Zhaohui; Suo, Liumin; Wang, Chunsheng

    2016-07-13

    All-solid-state lithium-sulfur batteries (ASSLSBs) using highly conductive sulfide-based solid electrolytes suffer from low sulfur utilization, poor cycle life, and low rate performance due to the huge volume change of the electrode and the poor electronic and ionic conductivities of S and Li2S. The most promising approach to mitigate these challenges lies in the fabrication of a sulfur nanocomposite electrode consisting of a homogeneous distribution of nanosized active material, solid electrolyte, and carbon. Here, we reported a novel bottom-up method to synthesize such a nanocomposite by dissolving Li2S as the active material, polyvinylpyrrolidone (PVP) as the carbon precursor, and Li6PS5Cl as the solid electrolyte in ethanol, followed by a coprecipitation and high-temperature carbonization process. Li2S active material and Li6PS5Cl solid electrolyte with a particle size of ∼4 nm were uniformly confined in a nanoscale carbon matrix. The homogeneous nanocomposite electrode consisting of different nanoparticles with distinct properties of lithium storage capability, mechanical reinforcement, and ionic and electronic conductivities enabled a mechanical robust and mixed conductive (ionic and electronic conductive) sulfur electrode for ASSLSB. A large reversible capacity of 830 mAh/g (71% utilization of Li2S) at 50 mA/g for 60 cycles with a high rate performance was achieved at room temperature even at a high loading of Li2S (∼3.6 mg/cm(2)). This work provides a new strategy to design a mechanically robust, mixed conductive nanocomposite electrode for high-performance all-solid-state lithium sulfur batteries.

  15. Analysis of band gap of non-bravais lattice photonic crystal fiber

    Institute of Scientific and Technical Information of China (English)

    Yichao MA; Heming CHEN

    2009-01-01

    This article designs a novel type ofnon-bravais lattice photonic crystal fiber. To form the nesting complexperiod with positive and negative refractive index materials respectively, a cylinder with the same radius and negative refractive index is introduced into the center of each lattice unit cell in the traditional square lattice air-holes photonic crystal fiber. The photonic band-gap of the photonic crystal fiber is calculated numerically by the plane wave expansion method. The result shows that compared with the traditional square photonic band-gap fiber (PBGF),when R/A is 0.35, the refractive index of the substrate, airhole, and medium-column are 1.30, 1.0, and -1.0,respectively. This new PBGF can transmit signal by the photonic band-gap effect. When the lattice constant Λvaries from 1.5 μm to 3.0 μm, the range of the wavelength ranges from 880 nm to 2300 nm.

  16. Influence of air pressure on soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, Peter John

    2009-01-01

    of obtaining pedestal-free output pulses. Particular emphasis is placed on the influence of the air pressure in the HC-PBG fiber. It is found that a reduction in air pressure enables an increase in the fraction of power going into the most redshifted soliton and also improves the quality of the filtered pulse...

  17. Photonic bandgap amorphous chalcogenide thin films with multilayered structure grown by pulsed laser deposition method

    Science.gov (United States)

    Zhang, Shao-qian; Němec, Petre; Nazabal, Virginie; Jin, Yu-qi

    2016-05-01

    Amorphous chalcogenide thin films were fabricated by the pulsed laser deposition technique. Thereafter, the stacks of multilayered thin films for reflectors and microcavity were designed for telecommunication wavelength. The prepared multilayered thin films for reflectors show good compatibility. The microcavity structure consists of Ge25Ga5Sb10S65 (doped with Er3+) spacer layer surrounded by two 5-layer As40Se60/Ge25Sb5S70 reflectors. Scanning/transmission electron microscopy results show good periodicity, great adherence and smooth interfaces between the alternating dielectric layers, which confirms a suitable compatibility between different materials. The results demonstrate that the chalcogenides can be used for preparing vertical Bragg reflectors and microcavity with high quality.

  18. Stability and bandgaps of layered perovskites for one- and two-photon water splitting

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; García Lastra, Juan Maria; Hüser, Falco;

    2013-01-01

    Direct production of hydrogen from water and sunlight requires stable and abundantly available semiconductors with well positioned band edges relative to the water red-ox potentials. We have used density functional theory (DFT) calculations to investigate 300 oxides and oxynitrides in the Ruddles......0@LDA gaps for 20 previously identified oxides and oxynitrides in the cubic perovskite structure....

  19. Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure.

    Science.gov (United States)

    Hwang, Beomyong; Hwang, Jeongwoon; Yoon, Jong Keon; Lim, Sungjun; Kim, Sungmin; Lee, Minjun; Kwon, Jeong Hoon; Baek, Hongwoo; Sung, Dongchul; Kim, Gunn; Hong, Suklyun; Ihm, Jisoon; Stroscio, Joseph A; Kuk, Young

    2016-08-09

    Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk.

  20. Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure

    Science.gov (United States)

    Hwang, Beomyong; Hwang, Jeongwoon; Yoon, Jong Keon; Lim, Sungjun; Kim, Sungmin; Lee, Minjun; Kwon, Jeong Hoon; Baek, Hongwoo; Sung, Dongchul; Kim, Gunn; Hong, Suklyun; Ihm, Jisoon; Stroscio, Joseph A.; Kuk, Young

    2016-08-01

    Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk.

  1. Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure

    Science.gov (United States)

    Hwang, Beomyong; Hwang, Jeongwoon; Yoon, Jong Keon; Lim, Sungjun; Kim, Sungmin; Lee, Minjun; Kwon, Jeong Hoon; Baek, Hongwoo; Sung, Dongchul; Kim, Gunn; Hong, Suklyun; Ihm, Jisoon; Stroscio, Joseph A.; Kuk, Young

    2016-01-01

    Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk. PMID:27503427

  2. Observation of excited-state excitons and band-gap renormalization in hole-doped carbon nanotubes using photoluminescence excitation spectroscopy

    OpenAIRE

    Kimoto, Yoshio; Okano, Makoto; Kanemitsu, Yoshihiko

    2013-01-01

    The higher Rydberg states of the E11 exciton in undoped and hole-doped single-walled carbon nanotubes (SWCNTs) were studied using one- and two-photon photoluminescence excitation spectroscopy. Increasing the hole-dopant concentration resulted in a redshift of the first excited state (2g) and a blueshift of the ground state (1u) of the E11 exciton. From the redshift of higher Rydberg states, we found that a reduction of the band-gap energy occurs in hole-doped SWCNTs. These findings show that ...

  3. High-efficiency, monolithic, multi-bandgap, tandem photovoltaic energy converters

    Science.gov (United States)

    Wanlass, Mark W.

    2011-11-29

    A monolithic, multi-bandgap, tandem solar photovoltaic converter has at least one, and preferably at least two, subcells grown lattice-matched on a substrate with a bandgap in medium to high energy portions of the solar spectrum and at least one subcell grown lattice-mismatched to the substrate with a bandgap in the low energy portion of the solar spectrum, for example, about 1 eV.

  4. Hallo photons calls photon; Allo photon appelle photon

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1997-09-01

    When a pair of photons is created, it seems that these 2 photons are bound together by a mysterious link. This phenomenon has been discovered at the beginning of the seventies. In this new experiment the 2 photons are separated and have to follow different ways through optic cables until they face a quantum gate. At this point they have to chose between a short and a long itinerary. Statistically they have the same probability to take either. In all cases the 2 photons agree to do the same choice even if the 2 quantum gates are distant of about 10 kilometers. Some applications in ciphering and coding of messages are expected. (A.C.)

  5. Overcoming the Cut-Off Charge Transfer Bandgaps at the PbS Quantum Dot Interface

    KAUST Repository

    El-Ballouli, Ala'a O.

    2015-11-17

    Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD-based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron-accepting unit with a new driving force for CT is urgently needed to harvest the light from large-sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time-resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD-based solar cells that make the best use of the diverse photons making up the Sun\\'s broad irradiance spectrum.

  6. Photonic Nanojets

    OpenAIRE

    Heifetz, Alexander; Kong, Soon-Cheol; Alan V. Sahakian; Taflove, Allen; Backman, Vadim

    2009-01-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for m...

  7. Origin of Sub-Bandgap Electroluminescence in Organic Light-Emitting Diodes.

    Science.gov (United States)

    Xiang, Chaoyu; Peng, Cheng; Chen, Ying; So, Franky

    2015-10-28

    Sub-bandgap electroluminescence in organic light emitting diodes is a phenomenon in which the electroluminescence turn-on voltage is lower than the bandgap voltage of the emitter. Based on the results of transient electroluminescence (EL) and photoluminescence and electroabsorption spectroscopy measurements, it is concluded that in rubrene/C60 devices, charge transfer excitons are generated at the rubrene/C60 interface under sub-bandgap driving conditions, leading to the formation of triplet excitons, and sub-bandgap EL is the result of the subsequent triplet-triplet annihilation process. PMID:26312783

  8. Photonic lanterns

    Science.gov (United States)

    Leon-Saval, Sergio G.; Argyros, Alexander; Bland-Hawthorn, Joss

    2013-12-01

    Multimode optical fibers have been primarily (and almost solely) used as "light pipes" in short distance telecommunications and in remote and astronomical spectroscopy. The modal properties of the multimode waveguides are rarely exploited and mostly discussed in the context of guiding light. Until recently, most photonic applications in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astrophotonics and space photonics. Interestingly, these devices are now being explored for use in telecommunications and are likely to find commercial use in the next few years, particularly in the development of compact spectrographs. Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail. Furthermore, we foreshadow future applications of this technology to the field of nanophotonics.

  9. Fabrication of Colloidal Photonic Crystals with Heterostructure by Spin-Coating Method

    Institute of Scientific and Technical Information of China (English)

    WANG Ai-Jun; CHEN Sheng-Li; DONG Peng; CAI Xiao-Gang; ZHOU Qian; YUAN Gui-Mei; HU Chun-Tian; ZANG Dao-Zhong

    2009-01-01

    Colloidal photonic crystal heterostructures, composed of two opaline photonic crystal films of silica spheres with different diameters, are fabricated by a two-step spin-coating method. Scanning electron microscopy (SEM) and UV-vis speetrophotometer are used to characterize the heterostructures. The SEM images show good ordering of the two-layer colloidal crystals constituting the heterostructures. The transmission spectra measured from the (111) plane in the heterostructure show that the composite colloidal photonic crystals have double photonic stop bands. Furthermore, when the sizes of the silica spheres used for fabricating the composite photonic crystal are slightly different, the transmission spectrum shows that the composite photonic crystals have more extended bandgap than that of the individual photonic crystals due to partial overlapping of its two photonie stop bands.

  10. New Curvature-Compensated CMOS Bandgap Voltage Reference

    Institute of Scientific and Technical Information of China (English)

    Lu Shen; Ning Ning; Qi Yu; Yan Luo; Chun-Sheng Li

    2007-01-01

    A novel curvaturecompensated CMOS bandgap voltage reference is presented. The reference utilizes two first order temperature compensations generated from the nonlinearity of the finite current gain β of vertical pnp bipolar transistor. The proposed circuit,designed in a standard 0.18 μm CMOS process, achieves a good temperature coefficient of 2.44 ppm/℃ with temperature range from 40 ℃ to 85 ℃, and about 4 mV supply voltage variation in the range from 1.4 V to 2.4 V. With a 1.8 V supply voltage, the power supply rejection ratio is 56 dB at 10 MHz.

  11. Chalcogenide glass hollow core photonic crystal fibers

    Science.gov (United States)

    Désévédavy, Frédéric; Renversez, Gilles; Troles, Johann; Houizot, Patrick; Brilland, Laurent; Vasilief, Ion; Coulombier, Quentin; Traynor, Nicholas; Smektala, Frédéric; Adam, Jean-Luc

    2010-09-01

    We report the first hollow core photonic crystal fibers (HC PCF) in chalcogenide glass. To design the required HC PCF profiles for such high index glass, we use both band diagram analysis to define the required photonic bandgap and numerical simulations of finite size HC PCFs to compute the guiding losses. The material losses have also been taken into account to compute the overall losses of the HC PCF profiles. These fibers were fabricated by the stack and draw technique from TeAsSe (TAS) glass. The fibers we drew in this work are composed of six rings of holes and regular microstructures. Two profiles are presented, one is known as a kagome lattice and the other one corresponds to a triangular lattice. Geometrical parameters are compared to the expected parameters obtained by computation. Applications of such fibers include power delivery or fiber sensors among others.

  12. Photonic-crystal-based all-optical NOT logic gate.

    Science.gov (United States)

    Singh, Brahm Raj; Rawal, Swati

    2015-12-01

    In the present paper, we have utilized the concept of photonic crystals for the implementation of an optical NOT gate inverter. The designed structure has a hexagonal arrangement of silicon rods in air substrate. The logic function is based on the phenomenon of the existence of the photonic bandgap and resulting guided modes in defect photonic crystal waveguides. We have plotted the transmission, extinction ratio, and tolerance analysis graphs for the structure, and it has been observed that the maximum output is obtained for a telecom wavelength of 1.554 μm. Dispersion curves are obtained using the plane wave expansion method, and the transmission is simulated using the finite element method. The proposed structure is applicable for photonic integrated circuits due to its simple structure and clear operating principle. PMID:26831380

  13. Photo-induced changes in a hybrid amorphous chalcogenide/silica photonic crystal fiber

    DEFF Research Database (Denmark)

    Markos, Christos

    2014-01-01

    Photostructural changes in a hybrid photonic crystal fiber with chalcogenide nanofilms inside the inner surface of the cladding holes are experimentally demonstrated. The deposition of the amorphous chalcogenide glass films inside the silica capillaries of the fiber was made by infiltrating...... the nanocolloidal solution-based As25S75, while the photoinduced changes were performed by side illuminating the fiber near the bandgap edge of the formed glass nanofilms. The photoinduced effect of the chalcogenide glass directly red-shifts the transmission bandgap position of the fiber as high as similar to 20...

  14. Graded bandgap semiconduc-tor thin film photoelectrodes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A graded bandgap oxide semiconductor thin film electrode was designed in order to obtain a photoelectrochemically stable photoelectrode, with wide absorption range. The graded bandgap Ti1-xVxO2 film electrode was prepared by heating the stacked layers of V/Ti in varying ratios, which were coated on the substrate by the sol-gel method using the starting solution with various V/Ti ratios. XPS result showed that the composition gradient was achieved for the film. The Ti1-xVxO2 film electrode was found to be photoelectrochemically stable. Its photovoltage was about 360 mV. Obvious visible light photoresponse was observed for the Ti1-xVxO2 film electrode. Compared with the pure TiO2 electrode, the photocurrent onset potential of the Ti1-xVxO2 film electrode was shifted positively, probably because the accumulation of vanadium at the electrode sur-face causes the recombination of the electrons and holes, and the lowest level of the conduction band of Ti1-xVxO2 is lower than that of TiO2. Impedance analysis showed that the donor density of the Ti1-xVxO2 film electrode was higher than that of TiO2 film electrode.

  15. Wide-bandgap epitaxial heterojunction windows for silicon solar cells

    Science.gov (United States)

    Landis, Geoffrey A.; Loferski, Joseph J.; Beaulieu, Roland; Sekula-Moise, Patricia A.; Vernon, Stanley M.

    1990-01-01

    It is shown that the efficiency of a solar cell can be improved if minority carriers are confined by use of a wide-bandgap heterojunction window. For silicon (lattice constant a = 5.43 A), nearly lattice-matched wide-bandgap materials are ZnS (a = 5.41 A) and GaP (a = 5.45 A). Isotype n-n heterojuntions of both ZnS/Si and GaP/Si were grown on silicon n-p homojunction solar cells. Successful deposition processes used were metalorganic chemical vapor deposition (MO-CVD) for GaP and ZnS, and vacuum evaporation of ZnS. Planar (100) and (111) and texture-etched - (111)-faceted - surfaces were used. A decrease in minority-carrier surface recombination compared to a bare surface was seen from increased short-wavelength spectral response, increased open-circuit voltage, and reduced dark saturation current, with no degradation of the minority carrier diffusion length.

  16. High Energy Density All Solid State Asymmetric Pseudocapacitors Based on Free Standing Reduced Graphene Oxide-Co3O4 Composite Aerogel Electrodes.

    Science.gov (United States)

    Ghosh, Debasis; Lim, Joonwon; Narayan, Rekha; Kim, Sang Ouk

    2016-08-31

    Modern flexible consumer electronics require efficient energy storage devices with flexible free-standing electrodes. We report a simple and cost-effective route to a graphene-based composite aerogel encapsulating metal oxide nanoparticles for high energy density, free-standing, binder-free flexible pseudocapacitive electrodes. Hydrothermally synthesized Co3O4 nanoparticles are successfully housed inside the microporous graphene aerogel network during the room temperature interfacial gelation at the Zn surface. The resultant three-dimensional (3D) rGO-Co3O4 composite aerogel shows mesoporous quasiparallel layer stack morphology with a high loading of Co3O4, which offers numerous channels for ion transport and a 3D interconnected network for high electrical conductivity. All solid state asymmetric pseudocapacitors employing the composite aerogel electrodes have demonstrated high areal energy density of 35.92 μWh/cm(2) and power density of 17.79 mW/cm(2) accompanied by excellent cycle life.

  17. 2.1-watts intracavity-frequency-doubled all-solid-state light source at 671 nm for laser cooling of lithium

    CERN Document Server

    Eismann, Ulrich; Salomon, Christophe; Chevy, Frédéric

    2013-01-01

    We present an all-solid-state laser source emitting up to 2.1 W of single-frequency light at 671 nm developed for laser cooling of lithium atoms. It is based on a diode-pumped, neodymium-doped orthovanadate (Nd:YVO$_4$) ring laser operating at 1342 nm. Optimization of the thermal management in the gain medium results in a maximum multi-frequency output power of 2.5 W at the fundamental wavelength. We develop a simple theory for the efficient implementation of intracavity second harmonic generation, and its application to our system allows us to obtain nonlinear conversion efficiencies of up to 88%. Single-mode operation and tuning is established by adding an etalon to the resonator. The second-harmonic wavelength can be tuned over 0.5 nm, and mode-hop-free scanning over more than 6 GHz is demonstrated, corresponding to around ten times the laser cavity free spectral range. The output frequency can be locked with respect to the lithium $D$-line transitions for atomic physics applications. Furthermore, we obser...

  18. A new solid polymer electrolyte incorporating Li10GeP2S12 into a polyethylene oxide matrix for all-solid-state lithium batteries

    Science.gov (United States)

    Zhao, Yanran; Wu, Chuan; Peng, Gang; Chen, Xiaotian; Yao, Xiayin; Bai, Ying; Wu, Feng; Chen, Shaojie; Xu, Xiaoxiong

    2016-01-01

    Li10GeP2S12 (LGPS) is incorporated into polyethylene oxide (PEO) matrix to fabricate composite solid polymer electrolyte (SPE) membranes. The lithium ion conductivities of as-prepared composite membranes are evaluated, and the optimal composite membrane exhibits a maximum ionic conductivity of 1.21 × 10-3 S cm-1 at 80 °C and an electrochemical window of 0-5.7 V. The phase transition behaviors for electrolytes are characterized by DSC, and the possible reasons for their enhanced ionic conductivities are discussed. The LGPS microparticles, acting as active fillers incorporation into the PEO matrix, have a positive effect on the ionic conductivity, lithium ion transference number and electrochemical stabilities. In addition, two kinds of all-solid-state lithium batteries (LiFeO4/SPE/Li and LiCoO2/SPE/Li) are fabricated to demonstrate the good compatibility between this new SPE membrane and different electrodes. And the LiFePO4/Li battery exhibits fascinating electrochemical performance with high capacity retention (92.5% after 50 cycles at 60 °C) and attractive capacities of 158, 148, 138 and 99 mAh g-1 at current rates of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C, respectively. It is demonstrated that this new composite SPE should be a promising electrolyte applied in solid state batteries based on lithium metal electrode.

  19. Note: All solid-state high repetitive sub-nanosecond risetime pulse generator based on bulk gallium arsenide avalanche semiconductor switches

    Science.gov (United States)

    Hu, Long; Su, Jiancang; Ding, Zhenjie; Hao, Qingsong; Fan, Yajun; Liu, Chunliang

    2016-08-01

    An all solid-state high repetitive sub-nanosecond risetime pulse generator featuring low-energy-triggered bulk gallium arsenide (GaAs) avalanche semiconductor switches and a step-type transmission line is presented. The step-type transmission line with two stages is charged to a potential of 5.0 kV also biasing at the switches. The bulk GaAs avalanche semiconductor switch closes within sub-nanosecond range when illuminated with approximately 87 nJ of laser energy at 905 nm in a single pulse. An asymmetric dipolar pulse with peak-to-peak amplitude of 9.6 kV and risetime of 0.65 ns is produced on a resistive load of 50 Ω. A technique that allows for repetition-rate multiplication of pulse trains experimentally demonstrated that the parallel-connected bulk GaAs avalanche semiconductor switches are triggered in sequence. The highest repetition rate is decided by recovery time of the bulk GaAs avalanche semiconductor switch, and the operating result of 100 kHz of the generator is discussed.

  20. High Energy Density All Solid State Asymmetric Pseudocapacitors Based on Free Standing Reduced Graphene Oxide-Co3O4 Composite Aerogel Electrodes.

    Science.gov (United States)

    Ghosh, Debasis; Lim, Joonwon; Narayan, Rekha; Kim, Sang Ouk

    2016-08-31

    Modern flexible consumer electronics require efficient energy storage devices with flexible free-standing electrodes. We report a simple and cost-effective route to a graphene-based composite aerogel encapsulating metal oxide nanoparticles for high energy density, free-standing, binder-free flexible pseudocapacitive electrodes. Hydrothermally synthesized Co3O4 nanoparticles are successfully housed inside the microporous graphene aerogel network during the room temperature interfacial gelation at the Zn surface. The resultant three-dimensional (3D) rGO-Co3O4 composite aerogel shows mesoporous quasiparallel layer stack morphology with a high loading of Co3O4, which offers numerous channels for ion transport and a 3D interconnected network for high electrical conductivity. All solid state asymmetric pseudocapacitors employing the composite aerogel electrodes have demonstrated high areal energy density of 35.92 μWh/cm(2) and power density of 17.79 mW/cm(2) accompanied by excellent cycle life. PMID:27494271

  1. Generation of 3.5W high efficiency blue-violet laser by intracavity frequency-doubling of an all-solid-state tunable Ti:sapphire laser.

    Science.gov (United States)

    Ding, X; Wang, R; Zhang, H; Wen, W Q; Huang, L; Wang, P; Yao, J Q; Yu, X Y; Li, Z

    2008-03-31

    In this paper, we report a high power, high efficiency blue-violet laser obtained by intracavity frequency-doubling of an all-solid-state Q-switched tunable Ti:sapphire laser, which was pumped by a 532 nm intracavity frequency-doubled Nd:YAG laser. A beta-BaB2O4 (BBO) crystal was used for frequency-doubling of the Ti:sapphire laser and a V-shape folded three-mirror cavity was optimized to obtain high power high efficiency second harmonic generation (SHG). At an incident pump power of 22 W, the tunable output from 355 nm to 475 nm was achieved, involving the maximum average output of 3.5 W at 400 nm with an optical conversion efficiency of 16% from the 532 nm pump laser to the blue-violet output. The beam quality factor M(2) was measured to be Mx(2)=2.15, My(2)=2.38 for characterizing the tunable blue laser.

  2. All-solid-state doubly resonant intracavity frequency sum mixing orange yellow laser with 3.2 W output power at 593.5 nm

    Science.gov (United States)

    Zhu, P. F.; Li, B.; Liu, W. Q.; Liu, T. H.; Fang, C. X.; Zhano, Y.; Yao, Y.; Zheng, Q.

    2013-01-01

    A compact and efficient 593.5 nm orange-yellow laser is realized using doubly resonant intracavity sum frequency mixing. Two Nd: YVO4 crystals are employed as the gain crystals. In two sub-cavities, 1064 nm radiation from one Nd: YVO4 and 1342 nm radiation from the other Nd: YVO4 are mixed to generate 593.5 nm orange-yellow laser. In the overlapping of the two cavities, sum frequency mixing is achieved in a type I critical phase matching (CPM) LBO crystal. An output power of 3.2 W at the wavelength of 593.5 nm is obtained with total incident pump power of 38 W. The optical to optical conversion efficiency is up to 8.4% and the stability of the output power is better than 2.48% in 8 h. To the best knowledge, this it the highest watt-level laser at 593.5 nm generated by diode end pump all-solid-state technology.

  3. T he Protection Technology of All-solid-state Modulator%全固态调制器的保护技术

    Institute of Scientific and Technical Information of China (English)

    王登峰; 田为; 谢英

    2016-01-01

    The all-solid-state hard tube modulator is widely used in the electro-vacuum transmitter and accelerator etc .In this paper, the troubles of the modulator using process are discussed .The fault causes are analyzed .The emphasis is placed on key technologies and measures , like switch tube voltage balance circuit , the protection of driving circuit , the protection on klystron arcing and the on-line detection methods of the switch tube .The typical circuit diagram is given .The prospects of the application are forecasted .%全固态刚管调制器现阶段已广泛应用于大功率发射机、加速器等众多领域中。针对固态调制器使用过程中出现的问题,分析了其故障原因,重点介绍了为保护固态开关和调制器采用的开关管均压、驱动信号保护、高压打火保护电路、开关管状态在线监测等关键技术和措施,给出了典型的应用电路,并对应用前景进行了展望。

  4. Generation of 3.5W high efficiency blue-violet laser by intracavity frequency-doubling of an all-solid-state tunable Ti:sapphire laser.

    Science.gov (United States)

    Ding, X; Wang, R; Zhang, H; Wen, W Q; Huang, L; Wang, P; Yao, J Q; Yu, X Y; Li, Z

    2008-03-31

    In this paper, we report a high power, high efficiency blue-violet laser obtained by intracavity frequency-doubling of an all-solid-state Q-switched tunable Ti:sapphire laser, which was pumped by a 532 nm intracavity frequency-doubled Nd:YAG laser. A beta-BaB2O4 (BBO) crystal was used for frequency-doubling of the Ti:sapphire laser and a V-shape folded three-mirror cavity was optimized to obtain high power high efficiency second harmonic generation (SHG). At an incident pump power of 22 W, the tunable output from 355 nm to 475 nm was achieved, involving the maximum average output of 3.5 W at 400 nm with an optical conversion efficiency of 16% from the 532 nm pump laser to the blue-violet output. The beam quality factor M(2) was measured to be Mx(2)=2.15, My(2)=2.38 for characterizing the tunable blue laser. PMID:18542555

  5. AC impedance analysis of ionic and electronic conductivities in electrode mixture layers for an all-solid-state lithium-ion battery

    Science.gov (United States)

    Siroma, Zyun; Sato, Tomohiro; Takeuchi, Tomonari; Nagai, Ryo; Ota, Akira; Ioroi, Tsutomu

    2016-06-01

    The ionic and electronic effective conductivities of an electrode mixture layers for all-solid-state lithium-ion batteries containing Li2Ssbnd P2S5 as a solid electrolyte were investigated by AC impedance measurements and analysis using a transmission-line model (TLM). Samples containing graphite (graphite electrodes) or LiNi0.5Co0.2Mn0.3O2 (NCM electrodes) as the active material were measured under a "substrate | sample | bulk electrolyte | sample | substrate" configuration (ion-electron connection) and a "substrate | sample | substrate" configuration (electron-electron connection). Theoretically, if the electronic resistance is negligibly small, which is the case with our graphite electrodes, measurement with the ion-electron connection should be effective for evaluating ionic conductivity. However, if the electronic resistance is comparable to the ionic resistance, which is the case with our NCM electrodes, the results with the ion-electron connection may contain some inherent inaccuracy. In this report, we theoretically and practically demonstrate the advantage of analyzing the results with the electron-electron connection, which gives both the ionic and electronic conductivities. The similarity of the behavior of ionic conductivity with the graphite and NCM electrodes confirms the reliability of this analysis.

  6. An Integrated Glucose Sensor with an All-Solid-State Sodium Ion-Selective Electrode for a Minimally Invasive Glucose Monitoring System

    Directory of Open Access Journals (Sweden)

    Junko Kojima

    2015-06-01

    Full Text Available We developed a minimally invasive glucose monitoring system that uses a microneedle to permeate the skin surface and a small hydrogel to accumulate interstitial fluid glucose. The measurement of glucose and sodium ion levels in the hydrogel is required for estimating glucose levels in blood; therefore, we developed a small, enzyme-fixed glucose sensor with a high-selectivity, all-solid-state, sodium ion-selective electrode (ISE integrated into its design. The glucose sensor immobilized glucose oxidase showed a good correlation between the glucose levels in the hydrogels and the reference glucose levels (r > 0.99, and exhibited a good precision (coefficient of variation = 2.9%, 0.6 mg/dL. In the design of the sodium ISEs, we used the insertion material Na0.33MnO2 as the inner contact layer and DD16C5 exhibiting high Na+/K+ selectivity as the ionophore. The developed sodium ISE exhibited high selectivity (\\( \\log \\,k^{pot}_{Na,K} = -2.8\\ and good potential stability. The sodium ISE could measure 0.4 mM (10−3.4 M sodium ion levels in the hydrogels containing 268 mM (10−0.57 M KCl. The small integrated sensor (ϕ < 10 mm detected glucose and sodium ions in hydrogels simultaneously within 1 min, and it exhibited sufficient performance for use as a minimally invasive glucose monitoring system.

  7. Disposable all-solid-state pH and glucose sensors based on conductive polymer covered hierarchical AuZn oxide.

    Science.gov (United States)

    Kim, Dong-Min; Cho, Seong Je; Cho, Chul-Ho; Kim, Kwang Bok; Kim, Min-Yeong; Shim, Yoon-Bo

    2016-05-15

    Poly(terthiophene benzoic acid) (pTBA) layered-AuZn alloy oxide (AuZnOx) deposited on the screen printed carbon electrode (pTBA/AuZnOx/SPCE) was prepared to create a disposable all-solid-state pH sensor at first. Further, FAD-glucose oxidase (GOx) was immobilized onto the pTBA/AuZnOx/SPCE to fabricate a glucose sensor. The characterizations of the sensor probe reveal that AuZnOx forms a homogeneous hierarchical structure, and that the polymerized pTBA layer on the alloy oxide surface captures GOx covalently. The benzoic acid group of pTBA coated on the probe layer synergetically improved the pH response of the alloy oxide and provide chemical binding sites to enzyme, which resulted in a Nernstian behavior (59.2 ± 0.5 mV/pH) in the pH range of 2-13. The experimental parameters affecting the glucose analysis were studied in terms of pH, temperature, humidity, and interferences. The sensor exhibited a fast response time <1s and a dynamic range between 30 and 500 mg/dL glucose with a detection limit of 17.23 ± 0.32 mg/dL. The reliabilities of the disposable pH and glucose sensors were examined for biological samples. PMID:26703994

  8. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers.

    Science.gov (United States)

    Petersen, Sidsel R; Alkeskjold, Thomas T; Lægsgaard, Jesper

    2013-07-29

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions. PMID:23938682

  9. Performance impact of luminescent coupling on monolithic 12-junction phototransducers for 12 V photonic power systems

    Science.gov (United States)

    Wilkins, Matthew; Valdivia, Christopher E.; Chahal, Sanmeet; Ishigaki, Masanori; Masson, Denis P.; Fafard, Simon; Hinzer, Karin

    2016-03-01

    A twelve-junction monolithically-integrated GaAs phototransducer device with >60% power conversion efficiency and >14 V open-circuit voltage under monochromatic illumination is presented. Drift-diffusion based simulations including a luminescent coupled generation term are used to study photon recycling and luminescent coupling between each junction. We find that luminescent coupling effectively redistributes any excess generated photocurrent between all junctions leading to reduced wavelength sensitivity. This broadened response is consistent with experimental measurements of devices with high-quality materials exhibiting long carrier lifetimes. Photon recycling is also found to significantly improve the voltage of all junctions, in contrast to multi-junction solar cells which utilize junctions of differing bandgaps and where high-bandgap junctions benefit less from photon recycling.

  10. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper

    2013-01-01

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump...... wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode...... area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions....

  11. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

    Science.gov (United States)

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2015-08-01

    YPO4:  Tm, Yb inverse opal photonic crystals were successfully synthesized by the colloidal crystal templates method, and the visible-infrared quantum cutting (QC) photoluminescence properties of YPO4:  Tm, Yb inverse opal photonic crystals were investigated. We obtained tetragonal phase YPO4 in all the samples when the samples sintered at 950°C for 5 h. The visible emission intensity of Tm3+ decreased significantly when the photonic bandgap was located at 650 nm under 480 nm excitation. On the contrary, the QC emission intensity of Yb3+ was enhanced as compared with the no photonic bandgap sample. When the photonic bandgap was located at 480 nm, the Yb3+ and Tm3+ light-emitting intensity weakened at the same time. We demonstrated that the energy transfer between Tm3+ and Yb3+ is enhanced by the suppression of the red emission of Tm3+. Additionally, the mechanisms for the influence of the photonic bandgap on the energy transfer process of the Tm3+, Yb3+ codoped YPO4 inverse opal are discussed.

  12. Testing QCD in Photon-Photon Interactions

    OpenAIRE

    Soldner-Rembold, Stefan

    1998-01-01

    At high energies photon-photon interactions are dominated by quantum fluctuations of the photons into fermion-antifermion pairs and into vector mesons. This is called photon structure. Electron-positron collisions at LEP are an ideal laboratory for studying photon structure and for testing QCD.

  13. High performance, high bandgap, lattice-mismatched, GaInP solar cells

    Science.gov (United States)

    Wanlass, Mark W.; Carapella, Jeffrey J.; Steiner, Myles A.

    2014-07-08

    High performance, high bandgap, lattice-mismatched, photovoltaic cells (10), both transparent and non-transparent to sub-bandgap light, are provided as devices for use alone or in combination with other cells in split spectrum apparatus or other applications.

  14. Investigating Bandgap Energies, Materials, and Design of Light-Emitting Diodes

    Science.gov (United States)

    Wagner, Eugene P., II

    2016-01-01

    A student laboratory experiment to investigate the intrinsic and extrinsic bandgaps, dopant materials, and diode design in light-emitting diodes (LEDs) is presented. The LED intrinsic bandgap is determined by passing a small constant current through the diode and recording the junction voltage variation with temperature. A second visible…

  15. Photonic crystals

    CERN Document Server

    Busch, Kurt; Wehrspohn, Ralf B; Föll, Helmut

    2006-01-01

    The majority of the contributions in this topically edited book stems from the priority program SPP 1113 ""Photonische Kristalle"" run by the Deutsche Forschungsgemeinschaft (DFG), resulting in a survey of the current state of photonic crystal research in Germany. The first part of the book describes methods for the theoretical analysis of their optical properties as well as the results. The main part is dedicated to the fabrication, characterization and modeling of two- and three-dimensional photonic crystals, while the final section presents a wide spectrum of applications: gas sensors, micr

  16. Vesicle Photonics

    Energy Technology Data Exchange (ETDEWEB)

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  17. FDTD analysis of photonic quasicrystals with different tiling geometries and fabrication by single beam computer-generated holography

    CERN Document Server

    Zito, G; Santamato, E; Marino, A; Tkachenko, V; Abbate, G

    2013-01-01

    Multiple-beam holography has been widely used for the realization of photonic quasicrystals with high rotational symmetries not achievable by the conventional periodic crystals. Accurate control of the properties of the interfering beams is necessary to provide photonic band-gap structures. Here we show, by FDTD simulations of the transmission spectra of 8-fold quasiperiodic structures, how the geometric tiling of the structure affects the presence and properties of the photonic band-gap for low refractive index contrasts. Hence, we show an interesting approach to the fabrication of photonic quasicrystals based on the use of a programmable Spatial Light Modulator encoding Computer-Generated Holograms, that permits an accurate control of the writing pattern with almost no limitations in the pattern design. Using this single-beam technique we fabricated quasiperiodic structures with high rotational symmetries and different geometries of the tiling, demonstrating the great versatility of our technique.

  18. Photonic crystals principles and applications

    CERN Document Server

    Gong, Qihuang

    2013-01-01

    IntroductionPrimary Properties of Photonic CrystalsFabrication of Photonic CrystalsPhotonic Crystal All-Optical SwitchingTunable Photonic Crystal FilterPhotonic Crystal LaserPhotonic Crystal Logic DevicesPhotonic Crystal Sensors

  19. Miniature all-solid-state heterostructure nanowire Li-ion batteries as a tool for engineering and structural diagnostics of nanoscale electrochemical processes.

    Science.gov (United States)

    Oleshko, Vladimir P; Lam, Thomas; Ruzmetov, Dmitry; Haney, Paul; Lezec, Henri J; Davydov, Albert V; Krylyuk, Sergiy; Cumings, John; Talin, A Alec

    2014-10-21

    Complex interfacial phenomena and phase transformations that govern the operation of Li-ion batteries require detailed nanoscale 3D structural and compositional characterization that can be directly related to their capacity and electrical transport properties. For this purpose, we have designed model miniature all solid-state radial heterostructure Li-ion batteries composed of LiCoO2 cathode, LiPON electrolyte and amorphous Si anode shells, which were deposited around metallized high-aspect-ratio Si nanowires as a scaffolding core. Such diagnostic batteries, the smallest, complete secondary Li-ion batteries realized to date, were specifically designed for in situ electrical testing in a field-emission scanning electron microscope and/or transmission electron microscope. The results of electrochemical testing were described in detail in a previous publication (Nano Lett., 2012, 12, 505-511). The model Li-ion batteries allow analysis of the correlations between electrochemical properties and their structural evolution during cycling in various imaging, diffraction and spectroscopic modes down to the atomic level. Employing multimode analytical scanning/transmission electron microscopy imaging coupled with correlative multivariate statistical analysis and tomography, we have analyzed and quantified the 3D morphological and structural arrangement of the batteries, including textured platelet-like LiCoO2 nanocrystallites, buried electrode-electrolyte interfaces and hidden internal defects to clarify effects of scaling on a battery's electrochemical performance. Characterization of the nanoscale interfacial processes using model heterostructure nanowire-based Li-ion batteries provides useful guidelines for engineering of prospective nano-sized building blocks in future electrochemical energy storage systems.

  20. Dynamic control of higher-order modes in hollow-core photonic crystal fibers.

    Science.gov (United States)

    Euser, T G; Whyte, G; Scharrer, M; Chen, J S Y; Abdolvand, A; Nold, J; Kaminski, C F; Russell, P St J

    2008-10-27

    We present a versatile method for selective mode coupling into higher-order modes of photonic crystal fibers, using holograms electronically generated by a spatial light modulator. The method enables non-mechanical and completely repeatable changes in the coupling conditions. We have excited higher order modes up to LP(31) in hollow-core photonic crystal fibers. The reproducibility of the coupling allows direct comparison of the losses of different guided modes in both hollow-core bandgap and kagome-lattice photonic crystal fibers. Our results are also relevant to applications in which the intensity distribution of the light inside the fiber is important, such as particle- or atom-guidance.

  1. Guidance in Kagome-like photonic crystal fibres I: analysis of an ideal fibre structure.

    Science.gov (United States)

    Chen, Lei; Pearce, Greg J; Birks, Timothy A; Bird, David M

    2011-03-28

    Propagation of light in a square-lattice hollow-core photonic crystal fibre is analysed as a model of guidance in a class of photonic crystal fibres that exhibit broad-band guidance without photonic bandgaps. A scalar governing equation is used and analytic solutions based on transfer matrices are developed for the full set of modes. It is found that an exponentially localised fundamental mode exists for a wide range of frequencies. These analytic solutions of an idealised structure will form the basis for analysis of guidance in a realistic structure in a following paper.

  2. Photon differentials

    DEFF Research Database (Denmark)

    Schjøth, Lars; Revall Frisvad, Jeppe; Erleben, Kenny;

    2007-01-01

    illumination features. This is often not desirable as these may lose clarity or vanish altogether. We present an accurate method for reconstruction of indirect illumination with photon mapping. Instead of reconstructing illumination using classic density estimation on finite points, we use the correlation...

  3. Photon Differentials

    DEFF Research Database (Denmark)

    Schjøth, Lars; Frisvad, Jeppe Revall; Erleben, Kenny;

    2007-01-01

    illumination features. This is often not desirable as these may lose clarity or vanish altogether. We present an accurate method for reconstruction of indirect illumination with photon mapping. Instead of reconstructing illumination using classic density estimation on finite points, we use the correlation...

  4. Two-Photon Absorption in Organometallic Bromide Perovskites

    KAUST Repository

    Walters, Grant

    2015-07-21

    Organometallic trihalide perovskites are solution processed semiconductors that have made great strides in third generation thin film light harvesting and light emitting optoelectronic devices. Recently it has been demonstrated that large, high purity single crystals of these perovskites can be synthesized from the solution phase. These crystals’ large dimensions, clean bandgap, and solid-state order, have provided us with a suitable medium to observe and quantify two-photon absorption in perovskites. When CH3NH3PbBr3 single crystals are pumped with intense 800 nm light, we observe band-to-band photoluminescence at 572 nm, indicative of two-photon absorption. We report the nonlinear absorption coefficient of CH3NH3PbBr3 perovskites to be 8.6 cm GW-1 at 800 nm, comparable to epitaxial single crystal semiconductors of similar bandgap. We have leveraged this nonlinear process to electrically autocorrelate a 100 fs pulsed laser using a two-photon perovskite photodetector. This work demonstrates the viability of organometallic trihalide perovskites as a convenient and low-cost nonlinear absorber for applications in ultrafast photonics.

  5. Alternative approaches of SiC & related wide bandgap materials in light emitting & solar cell applications

    Science.gov (United States)

    Wellmann, Peter; Syväjärvi, Mikael; Ou, Haiyan

    2014-03-01

    silicon oxycarbide material can provide potential applications of the Eu luminescent materials to challenging conditions like high temperatures or aggressive environments where the silica has weaknesses. In some approaches, silicon rich silicon oxide that contain silicon nanoclusters emit red to near infrared luminescence due to quantum confinement effects while luminescence at shorter wavelength is difficult due to the interplay of defects and quantum confinement effects. In addition it is applicable as low-k dielectric, etch-stop and passivation layers. It also has an optical band-gap that is smaller than that of SiO2 which may facilitate carrier injection at lower voltages that is suitable for optoelectronics. From materials perspective of emerging materials, it seems distant to consider system related issues. The future demands on communication and lighting devices require higher information flows in modernized optical devices, for example by replacing electrical interconnects with their optical counterparts and tunable backgrounds filters for integrated optics or photonics applications. However, there are materials issues related to such device performance, for example by a non-linearity, that provide the possibility for selective removal or addition of wavelengths using hetero structures in which one side of the structure enhances the light-to-dark sensitivity of long and medium wavelength channels and diminish others, and an opposite behavior in other face of the structure. Certainly materials may be applied in various innovative ways to provide new performances in devices and systems. In any materials and device evaluation, reliability issues in passivation and packaging of semiconductor device structures provide a base knowledge that may be used to evaluate new concepts. Fundamental aspects of dielectric constant, bandgap and band offsets between the valence and conduction band edges between the passivation layer and the semiconductor create a foundation for

  6. Self-assembled guanine ribbons as wide-bandgap semiconductors

    Science.gov (United States)

    di Felice, Rosa; Calzolari, Arrigo; Molinari, Elisa; Garbesi, Anna; Rinaldi, Ross; Maruccio, Giuseppe; Cingolani, Roberto

    2002-03-01

    We present a new class of biomolecular wide-bandgap semiconductors, that spontaneously form by the self-assembling of deoxyguanosine molecules (a modified DNA base) in the solid state. Their deposition onto planar metallic nanocircuits allows the fabrication of hybrid nanodiodes and metal/semiconductor/metal devices. By means of first-principle calculations, we describe the structure and the electronic properties of stacked guanine ribbons. We discuss the formation of extended Bloch orbitals, resulting from the superposition of base-localized states, as a function of H-bonding and π-π coupling. The oveall band-like conduction is affected by a dipole-field that spontaneously arise along the ribb n axis. Our theoretical model explains both the basic transport mechanism and the current-voltage characteristics of the devices.

  7. Low voltage bandgap reference with closed loop curvature compensation

    Institute of Scientific and Technical Information of China (English)

    Fan Tao; Du Bo; Zhang Zheng; Yuan Guoshun

    2009-01-01

    A new low-voltage CMOS bandgap reference (BGR) that achieves high temperature stability is proposed. It feeds back the output voltage to the curvature compensation circuit that constitutes a closed loop circuit to cancel the logarithmic term of voltage VBE. Meanwhile a low voltage amplifier with the 0.5μm low threshold technology is designed for the BGR. A high temperature stability BGR circuit is fabricated in the CSMC 0.5μm CMOS tech-nology. The measured result shows that the BGR can operate down to 1 V, while the temperature coefficient and line regulation are only 9 ppm/℃ and 1.2 mV/V, respectively.

  8. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Carrington, P. J. [Department of Electronic and Electrical Engineering, University College London, London (United Kingdom); Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  9. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    International Nuclear Information System (INIS)

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  10. Bandgap Engineering in High-Efficiency Multijunction Concentrator Cells

    Energy Technology Data Exchange (ETDEWEB)

    King, R. R.; Sherif, R. A.; Kinsey, G. S.; Kurtz, S.; Fetzer, C. M.; Edmondson, K. M.; Law, D. C.; Cotal, H. L.; Krut, D. D.; Ermer, J. H.; Karam, N. H.

    2005-08-01

    This paper discusses semiconductor device research paths under investigation with the aim of reaching the milestone efficiency of 40%. A cost analysis shows that achieving very high cell efficiencies is crucial for the realization of cost-effective photovoltaics, because of the strongly leveraging effect of efficiency on module packaging and balance-of systems costs. Lattice-matched (LM) GaInP/ GaInAs/ Ge 3-junction cells have achieved the highest independently confirmed efficiency at 175 suns, 25?C, of 37.3% under the standard AM1.5D, low-AOD terrestrial spectrum. Lattice-mismatched, or metamorphic (MM), materials offer still higher potential efficiencies, if the crystal quality can be maintained. Theoretical efficiencies well over 50% are possible for a MM GaInP/ 1.17-eV GaInAs/ Ge 3-junction cell limited by radiative recombination at 500 suns. The bandgap - open circuit voltage offset, (Eg/q) - Voc, is used as a valuable theoretical and experimental tool to characterize multijunction cells with subcell bandgaps ranging from 0.7 to 2.1 eV. Experimental results are presented for prototype 6-junction cells employing an active {approx}1.1-eV dilute nitride GaInNAs subcell, with active-area efficiency greater than 23% and over 5.3 V open-circuit voltage under the 1-sun AM0 space spectrum. Such cell designs have theoretical efficiencies under the terrestrial spectrum at 500 suns concentration exceeding 55% efficiency, even for lattice-matched designs.

  11. Photon-Photon Scattering at the Photon Linear Collider

    OpenAIRE

    Jikia, G.; Tkabladze, A.

    1993-01-01

    Photon-photon scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to $W$ boson loops are presented. It is shown that photon-photon scattering should be easily observable at PLC and separation of the $W$ loop contribution (which dominates at high energies) will be possible at $e^+e^-$ c.m. energy of 500~GeV or higher.

  12. Photon Collider Physics with Real Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  13. Microalgae photonics

    Science.gov (United States)

    Floume, Timmy; Coquil, Thomas; Sylvestre, Julien

    2011-05-01

    Due to their metabolic flexibility and fast growth rate, microscopic aquatic phototrophs like algae have a potential to become industrial photochemical converters. Algae photosynthesis could enable the large scale production of clean and renewable liquid fuels and chemicals with major environmental, economic and societal benefits. Capital and operational costs are the main issues to address through optical, process and biochemical engineering improvements. In this perspective, a variety of photonic approaches have been proposed - we introduce them here and describe their potential, limitations and compatibility with separate biotechnology and engineering progresses. We show that only sunlight-based approaches are economically realistic. One of photonics' main goals in the algae field is to dilute light to overcome photosaturation effects that impact upon cultures exposed to full sunlight. Among other approaches, we introduce a widely-compatible broadband spectral adaptation technique called AlgoSun® that uses luminescence to optimize sunlight spectrum in view of the bioconverter's requirements.

  14. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    Science.gov (United States)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  15. C-atom-induced bandgap modulation in two-dimensional (100) silicon carbon alloys

    Science.gov (United States)

    Mizuno, Tomohisa; Nagamine, Yoshiki; Omata, Yuhsuke; Suzuki, Yuhya; Urayama, Wako; Aoki, Takashi; Sameshima, Toshiyuki

    2016-04-01

    We experimentally studied the effects of the C atom on bandgap E G modulation in two-dimensional (2D) silicon carbon alloys, Si1- Y C Y , fabricated by hot C+ ion implantation into the (100) SOI substrate in a wide range of Y (4 × 10-5 ≤ Y ≤ 0.13), in comparison with the characteristics of 3D silicon carbide (SiC). X-ray photoelectron spectroscopy (XPS) and UV-Raman analysis confirm the Si-C, C-C, and Si-Si bonds in the 2D-Si1- Y C Y layer. The photoluminescence (PL) method shows that the E G and PL intensity I PL of 2D-Si1- Y C Y drastically increase with increasing Y for high Y (≥0.005), and thus we demonstrated a high E G of 2.5 eV and a visible wavelength λPL less than 500 nm. Even for low Y (<10-3), I PL of 2D-Si1- Y C Y also increases with increasing Y, owing to the compressive strain of the 2D-Si1- Y C Y layer caused by the C atoms, but the Y dependence of E G is very small. E G of 2D-Si1- Y C Y can be controlled by changing Y. Thus, the 2D-Si1- Y C Y technique is very promising for new E G engineering of future high-performance CMOS and Si photonics.

  16. Photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  17. Photon detectors

    International Nuclear Information System (INIS)

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF2 windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission

  18. Nanowire photonics

    OpenAIRE

    Peter J. Pauzauskie; Peidong Yang

    2006-01-01

    The development of integrated electronic circuitry ranks among the most disruptive and transformative technologies of the 20th century. Even though integrated circuits are ubiquitous in modern life, both fundamental and technical constraints will eventually test the limits of Moore's law. Nanowire photonic circuitry constructed from myriad one-dimensional building blocks offers numerous opportunities for the development of next-generation optical information processors and spectroscopy. Howev...

  19. Topological photonics

    OpenAIRE

    Lu, Ling; Joannopoulos, John D.; Soljačić, Marin

    2014-01-01

    The application of topology, the mathematics of conserved properties under continuous deformations, is creating a range of new opportunities throughout photonics. This field was inspired by the discovery of topological insulators, in which interfacial electrons transport without dissipation, even in the presence of impurities. Similarly, the use of carefully designed wavevector-space topologies allows the creation of interfaces that support new states of light with useful and interesting prop...

  20. Calibration processes for photon-photon colliders

    CERN Document Server

    Bartos, E; Galynsky, M V; Kuraev, E A

    2004-01-01

    Processes with creation of a pair charged particles with emission of hard photon and two pairs of charged particles are considered for colliding partially polarized photon photon beams. The effects of circular and linear polarization of the initial photons are discussed in more detail.