WorldWideScience

Sample records for all-solid photonic bandgap

  1. 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.

  2. 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.

  3. In-line Mach-Zehnder interferometer composed of microtaper and long-period grating in all-solid photonic bandgap fiber

    Energy Technology Data Exchange (ETDEWEB)

    Wu Zhifang [Key Laboratory of Optical Information and Technology, Ministry of Education and Institute of Modern Optics, Nankai University, Tianjin 300071 (China); OPTIMUS, School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 637553 (Singapore); Liu Yange; Wang Zhi; Han Tingting; Li Shuo [Key Laboratory of Optical Information and Technology, Ministry of Education and Institute of Modern Optics, Nankai University, Tianjin 300071 (China); Jiang Meng; Ping Shum, Perry [OPTIMUS, School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 637553 (Singapore); CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Quyen Dinh, Xuan [CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Thales Solutions Asia Pte Ltd, R and T Department, 28 Changi North Rise, Singapore 498755 (Singapore)

    2012-10-01

    We report a compact in-line Mach-Zehnder interferometer combining a microtaper with a long-period grating (LPG) in a section of all-solid photonic bandgap fiber. Theoretical and experimental investigations reveal that the interferometer works from the interference between the fundamental core mode and the LP{sub 01} cladding supermodes. The mechanism underlying the mode coupling caused by the microtaper can be attributed to a bandgap-shifting as the fiber diameter is abruptly scaled down. In addition, the interferometer designed to strengthen the coupling ratio of the long-period grating has a promising practical application in the simultaneous measurement of curvature and temperature.

  4. Multiple resonant coupling mechanism for suppression of higher-order modes in all-solid photonic bandgap fibers with heterostructured cladding.

    Science.gov (United States)

    Murao, Tadashi; Saitoh, Kunimasa; Koshiba, Masanori

    2011-01-31

    In this paper, we propose a novel mechanism for suppression of higher-order modes (HOMs), namely multiple resonant coupling, in all-solid photonic bandgap fibers (PBGFs) with effectively large core diameters. In an analogy to the well-known tight-binding theory in solid-state physics, multiple anti-resonant reflecting optical waveguide (ARROW) modes bound in designedly arranged defects in the cladding make up Bloch states and resultant photonic bands with a finite effective-index width, which contribute to the suppression of HOMs. In particular, contrary to the conventional method for the HOM suppression using the index-matching of the HOMs in the core of the PBGF and the defect mode arranged in the cladding, the proposed mechanism guarantees a broadband HOM suppression without a precise structural design. This effect is explained by the multiple resonant coupling, as well as an enhanced confinement loss mechanism which occurs near the condition satisfying the multiple resonant coupling. Moreover, we show that the proposed structure exhibits a lower bending loss characteristic when compared to the conventional all-solid PBGFs. The simultaneous realization of the single-mode operation and the low bending loss property is due to the novel cladding concept named as heterostructured cladding. The proposed structure also resolves the issue for the increased confinement loss property in the first-order photonic bandgap (PBG) at the same time.

  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 Bandgaps in Photonic Molecules

    Science.gov (United States)

    Smith, David D.; Chang, Hongrok; Gates, Amanda L.; Fuller, Kirk A.; Gregory, Don A.; Witherow, William K.; Paley, Mark S.; Frazier, Donald O.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    This talk will focus on photonic bandgaps that arise due to nearly free photon and tight-binding effects in coupled microparticle and ring-resonator systems. The Mie formulation for homogeneous spheres is generalized to handle core/shell systems and multiple concentric layers in a manner that exploits an analogy with stratified planar systems, thereby allowing concentric multi-layered structures to be treated as photonic bandgap (PBG) materials. Representative results from a Mie code employing this analogy demonstrate that photonic bands arising from nearly free photon effects are easily observed in the backscattering, asymmetry parameter, and albedo for periodic quarter-wave concentric layers, though are not readily apparent in extinction spectra. Rather, the periodicity simply alters the scattering profile, enhancing the ratio of backscattering to forward scattering inside the bandgap, in direct analogy with planar quarter-wave multilayers. PBGs arising from tight-binding may also be observed when the layers (or rings) are designed such that the coupling between them is weak. We demonstrate that for a structure consisting of N coupled micro-resonators, the morphology dependent resonances split into N higher-Q modes, in direct analogy with other types of oscillators, and that this splitting ultimately results in PBGs which can lead to enhanced nonlinear optical effects.

  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. 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....

  10. Hollow multilayer photonic bandgap fibers for NIR applications

    Science.gov (United States)

    Kuriki, Ken; Shapira, Ofer; Hart, Shandon D.; Benoit, Gilles; Kuriki, Yuka; Viens, Jean F.; Bayindir, Mehmet; Joannopoulos, John D.; Fink, Yoel

    2004-04-01

    Here we report the fabrication of hollow-core cylindrical photonic bandgap fibers with fundamental photonic bandgaps at near-infrared wavelengths, from 0.85 to 2.28 μm. In these fibers the photonic bandgaps are created by an all-solid multilayer composite meso-structure having a photonic crystal lattice period as small as 260 nm, individual layers below 75 nm and as many as 35 periods. These represent, to the best of our knowledge, the smallest period lengths and highest period counts reported to date for hollow PBG fibers. The fibers are drawn from a multilayer preform into extended lengths of fiber. Light is guided in the fibers through a large hollow core that is lined with an interior omnidirectional dielectric mirror. We extend the range of materials that can be used in these fibers to include poly(ether imide) (PEI) in addition to the arsenic triselenide (As2Se3) glass and poly(ether sulfone) (PES) that have been used previously. Further, we characterize the refractive indices of these materials over a broad wavelength range (0.25 - 15 μm) and incorporated the measured optical properties into calculations of the fiber photonic band structure and a preliminary loss analysis.

  11. Multidimensional microstructured photonic device based on all-solid waveguide array fiber and magnetic fluid

    Science.gov (United States)

    Miao, Yinping; Ma, Xixi; He, Yong; Zhang, Hongmin; Yang, Xiaoping; Yao, Jianquan

    2017-01-01

    An all-solid waveguide array fiber (WAF) is one kind of special microstructured optical fiber in which the higher-index rods are periodically distributed in a low-index silica host to form the transverse two-dimensional photonic crystal. In this paper, one kind of multidimensional microstructured optical fiber photonic device is proposed by using electric arc discharge method to fabricate periodic tapers along the fiber axis. By tuning the applied magnetic field intensity, the propagation characteristics of the all-solid WAF integrated with magnetic fluid are periodically modulated in both radial and axial directions. Experimental results show that the wavelength changes little while the transmission loss increases for an applied magnetic field intensity range from 0 to 500 Oe. The magnetic field sensitivity is 0.055 dB/Oe within the linear range from 50 to 300 Oe. Meanwhile, the all-solid WAF has very similar thermal expansion coefficient for both high- and low-refractive index glasses, and thermal drifts have a little effect on the mode profile. The results show that the temperature-induced transmission loss is <0.3 dB from 26°C to 44°C. Further tuning coherent coupling of waveguides and controlling light propagation, the all-solid WAF would be found great potential applications to develop new micro-nano photonic devices for optical communications and optical sensing applications.

  12. Multidimensional microstructured photonic device based on all-solid waveguide array fiber and magnetic fluid

    Directory of Open Access Journals (Sweden)

    Miao Yinping

    2016-11-01

    Full Text Available An all-solid waveguide array fiber (WAF is one kind of special microstructured optical fiber in which the higher-index rods are periodically distributed in a low-index silica host to form the transverse two-dimensional photonic crystal. In this paper, one kind of multidimensional microstructured optical fiber photonic device is proposed by using electric arc discharge method to fabricate periodic tapers along the fiber axis. By tuning the applied magnetic field intensity, the propagation characteristics of the all-solid WAF integrated with magnetic fluid are periodically modulated in both radial and axial directions. Experimental results show that the wavelength changes little while the transmission loss increases for an applied magnetic field intensity range from 0 to 500 Oe. The magnetic field sensitivity is 0.055 dB/Oe within the linear range from 50 to 300 Oe. Meanwhile, the all-solid WAF has very similar thermal expansion coefficient for both high- and low-refractive index glasses, and thermal drifts have a little effect on the mode profile. The results show that the temperature-induced transmission loss is <0.3 dB from 26°C to 44°C. Further tuning coherent coupling of waveguides and controlling light propagation, the all-solid WAF would be found great potential applications to develop new micro-nano photonic devices for optical communications and optical sensing applications.

  13. Loss properties of all-solid photonic band gap fibers with an array of rings

    Institute of Scientific and Technical Information of China (English)

    GENG You-fu; LI Xue-jin; TAN Xiao-ling; YAO Jian-quan

    2010-01-01

    @@ The confinement loss and bend loss properties of all-solid photonic band gap fibers with an array of rings doped with highindex material are investigated.The calculated results show that for a specific structure,the confinement loss and the critical bend radius are reduced simultaneously in some band gaps by increasing the inner diameter of ring,which provides a useful guide and a theoretical basis for designing large mode area fibers with low loss.

  14. 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 thesis addresses these two fundamental properties in both hollow core photonic crystal fibers and solid photonic bandgap fibers. Transmission loss in hollow core photonic crystal fibers is dominated by light scattering at the silica surfaces inside the fiber. In the current work it has been...... experimentally demonstrated that the minimum loss wavelength is located in the spectral region around 2000 nm, where the transmission loss in these fibers is significantly lower than in conventional solid silica fibers. Additionally it has been shown that transmission loss can be lowered roughly 40...

  15. Liquid Crystal photonic Bandgap Fiber Devices

    DEFF Research Database (Denmark)

    Wei, Lei

    In this Ph.D. thesis, an experimental investigation of liquid crystal photonic bandgap (LCPBG) fiber devices and applications is presented. Photonic crystal fibers (PCFs) consist of a cladding microstructure with periodic index variations and a core defined by a defect of the structure....... The presence of liquid crystals (LCs) in the air-holes of the PCF transforms the fiber from a total internal reflection (TIR) guiding type into a photonic bandgap (PBG) guiding type. The light is confined to the silica core by coherent scattering from the LC-filled air-holes and the transmission spectrum...... of each LCPBG fiber. Finally, the applications for LCPBG fiber devices based on the on-chip platform design have been demonstrated in realizing microwave true-time delay and creating an electrically tunable fiber laser. Referatet mailes...

  16. 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.

  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. Jacquard-woven photonic bandgap fiber displays

    CERN Document Server

    Sayed, Imran; Skorobogatiy, Maksim

    2010-01-01

    We present an overview of photonic textile displays woven on a Jacquard loom, using newly discovered polymer photonic bandgap fibers that have the ability to change color and appearance when illuminated with ambient or transmitted light. The photonic fiber can be thin (smaller than 300 microns in diameter) and highly flexible, which makes it possible to weave in the weft on a computerized Jacquard loom and develop intricate double weave structures together with a secondary weft yarn. We demonstrate how photonic crystal fibers enable a variety of color and structural patterns on the textile, and how dynamic imagery can be created by balancing the ambient and emitted radiation. Finally, a possible application in security ware for low visibility conditions is described as an example.

  19. Quantum electrodynamics near a photonic bandgap

    Science.gov (United States)

    Liu, Yanbing; Houck, Andrew A.

    2017-01-01

    Photonic crystals are a powerful tool for the manipulation of optical dispersion and density of states, and have thus been used in applications from photon generation to quantum sensing with nitrogen vacancy centres and atoms. The unique control provided by these media makes them a beautiful, if unexplored, playground for strong-coupling quantum electrodynamics, where a single, highly nonlinear emitter hybridizes with the band structure of the crystal. Here we demonstrate that such a hybridization can create localized cavity modes that live within the photonic bandgap, whose localization and spectral properties we explore in detail. We then demonstrate that the coloured vacuum of the photonic crystal can be employed for efficient dissipative state preparation. This work opens exciting prospects for engineering long-range spin models in the circuit quantum electrodynamics architecture, as well as new opportunities for dissipative quantum state engineering.

  20. 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.

  1. 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 al...

  2. All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

    Science.gov (United States)

    Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

    2016-02-01

    We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

  3. Polarizing 50micrometers Core Yb-Doped Photonic Bandgap Fiber

    Science.gov (United States)

    2015-02-08

    properly. Recent reports demonstrate that the birefringence in photonic bandgap fibers (PBFs) can provide single-polarization operation by shifting the...add ref]. Here, we demonstrate a 50µm core Yb-doped polarizing photonic bandgap fiber (PBF) for single-polarization operation 1. REPORT DATE (DD-MM...19-08-2015 Approved for public release; distribution is unlimited. Polarizing 50µm core Yb-doped photonic bandgap fiber The views, opinions and/or

  4. 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...... of high-power pulses. The low overlap between light and glass affects both the loss and nonlinear properties of the fiber. At the same time, the strong overlap between light and air provides a mean for creating convenient gas-filled devices with extremely long interaction lengths. In this project...

  5. 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.

  6. 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.

  7. 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...

  8. Microresonator and associated method for producing and controlling photonic signals with a photonic bandgap delay apparatus

    Science.gov (United States)

    Fork, Richard Lynn (Inventor); Jones, Darryl Keith (Inventor); Keys, Andrew Scott (Inventor)

    2000-01-01

    By applying a photonic signal to a microresonator that includes a photonic bandgap delay apparatus having a photonic band edge transmission resonance at the frequency of the photonic signal, the microresonator imparts a predetermined delay to the photonic signal. The photonic bandgap delay apparatus also preferably has a photonic band edge transmission resonance bandwidth which is at least as wide as the bandwidth of the photonic signal such that a uniform delay is imparted over the entire bandwidth of the photonic signal. The microresonator also includes a microresonator cavity, typically defined by a pair of switchable mirrors, within which the photonic bandgap delay apparatus is disposed. By requiring the photonic signal to oscillate within the microresonator cavity so as to pass through the photonic bandgap delay apparatus several times, the microresonator can controllably impart an adjustable delay to the photonic signal.

  9. 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....

  10. 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....

  11. 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.

  12. 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.

  13. 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...

  14. Coherent supercontinuum bandwidth limitations under femtosecond pumping at 2 µm in all-solid soft glass photonic crystal fibers

    DEFF Research Database (Denmark)

    Klimczak, Mariusz; Siwicki, Bartłomiej; Zhou, Binbin;

    2016-01-01

    Two all-solid glass photonic crystal fibers with all-normal dispersion profiles are evaluated for coherent supercontinuum generation under pumping in the 2.0 μm range. Inhouse boron-silicate and commercial lead-silicate glasses were used to fabricate fibers optimized for either flat dispersion......, albeit with lower nonlinearity, or with larger dispersion profile curvature but with much higher nonlinearity. Recorded spectra at the redshifted edge reached 2500-2800 nm depending on fiber type. Possible factors behind these differences are discussed with numerical simulations. The fiber enabling...

  15. Compact electrically controlled broadband liquid crystal photonic bandgap fiber polarizer

    DEFF Research Database (Denmark)

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

    2009-01-01

    An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm.......An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm....

  16. High extinction ratio bandgap of photonic crystals in LNOI wafer

    Science.gov (United States)

    Zhang, Shao-Mei; Cai, Lu-Tong; Jiang, Yun-Peng; Jiao, Yang

    2017-02-01

    A high-extinction-ratio bandgap of air-bridge photonic crystal slab, in the near infrared, is reported. These structures were patterned in single-crystalline LiNbO3 film bonded to SiO2/LiNbO3 substrate by focused ion beam. To improve the vertical confinement of light, the SiO2 layer was removed by 3.6% HF acid. Compared with photonic crystals sandwiched between SiO2 and air, the structures suspending in air own a robust photonic bandgap and high transmission efficiency at valence band region. The measured results are in good agreement with numerically computed transmission spectra by finite-difference time-domain method. The air-bridge photonic crystal waveguides were formed by removing one line holes. We reveal experimentally the guiding characteristics and calculate the theoretical results for photonic crystal waveguides in LiNbO3 film.

  17. Silica-air photonic crystal fiber design that permits waveguiding by a true photonic bandgap effect

    DEFF Research Database (Denmark)

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

    1999-01-01

    photonic crystal fibers. The novel fiber has a central low-index core region and a cladding consisting of a silica background material with air holes situated within a honeycomb lattice structure. We show the existence of photonic bandgaps for the silica–air cladding structure and demonstrate how light can...... be guided at the central low-index core region for a well-defined frequency that falls inside the photonic bandgap region of the cladding structure....

  18. Quantum electrodynamics near a photonic band-gap

    Science.gov (United States)

    Liu, Yanbing; Houck, Andrew

    Quantum electrodynamics predicts the localization of light around an atom in photonic band-gap (PBG) medium or photonic crystal. Here we report the first experimental realization of the strong coupling between a single artificial atom and an one dimensional PBG medium using superconducting circuits. In the photonic transport measurement, we observe an anomalous Lamb shift and a large band-edge avoided crossing when the artificial atom frequency is tuned across the band-edge. The persistent peak within the band-gap indicates the single photon bound state. Furthermore, we study the resonance fluorescence of this bound state, again demonstrating the breakdown of the Born-Markov approximation near the band-edge. This novel architecture can be directly generalized to study many-body quantum electrodynamics and to construct more complicated spin chain models.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    Purpose - To demonstrate the flexibility and advantages of a non-uniform pseudo-spectral time domain (nu-PSTD) method through studies of the wave propagation characteristics on photonic band-gap (PBG) structures in stratified medium Design/methodology/approach - A nu-PSTD method is proposed...

  20. 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 applicatio...

  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. Spontaneous emission and nonlinear effects in photonic bandgap materials

    Science.gov (United States)

    Fogel, Ishella S.; Bendickson, Jon M.; Tocci, Michael D.; Bloemer, Mark J.; Scalora, Michael; Bowden, Charles M.; Dowling, Jonathan P.

    1998-03-01

    We summarize and review our theoretical and experimental work on spontaneous emission and nonlinear effects in one-dimensional, photonic bandgap (PBG) structures. We present a new result: a method for calculating the normal-mode solutions - and hence the spontaneous emission of embedded emitters - in an arbitrary, linear, lossless, one-dimensional, PBG structure.

  4. Photonic bandgap fibers: theory and experiments

    DEFF Research Database (Denmark)

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

    2000-01-01

    to localize modes in the core region by the photonic band gap (PBG) effect. The photonic crystal fibers (PCFs) were first proposed for a high-index-core region, surrounded by a periodic dielectric structure consisting of a matrix of microscopic holes placed in a silica-glass-base material....

  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....

  6. Electrially tunable photonic bandgap guidance in a liquid crystal filled photonic crystal fiber

    DEFF Research Database (Denmark)

    Haakestad, Magnus W.; Alkeskjold, Thomas Tanggaard; Nielsen, Martin Dybendal;

    2005-01-01

    Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range.......Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range....

  7. 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 importan...

  8. Biased liquid crystal infiltrated photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Scolari, Lara

    2009-01-01

    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...

  9. Photonic bandgap narrowing in conical hollow core Bragg fibers

    Energy Technology Data Exchange (ETDEWEB)

    Ozturk, Fahri Emre; Yildirim, Adem; Kanik, Mehmet [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Bayindir, Mehmet, E-mail: bayindir@nano.org.tr [UNAM-National Nanotechnology Research Center, Bilkent University, 06800 Ankara (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Physics, Bilkent University, 06800 Ankara (Turkey)

    2014-08-18

    We report the photonic bandgap engineering of Bragg fibers by controlling the thickness profile of the fiber during the thermal drawing. Conical hollow core Bragg fibers were produced by thermal drawing under a rapidly alternating load, which was applied by introducing steep changes to the fiber drawing speed. In conventional cylindrical Bragg fibers, light is guided by omnidirectional reflections from interior dielectric mirrors with a single quarter wave stack period. In conical fibers, the diameter reduction introduced a gradient of the quarter wave stack period along the length of the fiber. Therefore, the light guided within the fiber encountered slightly smaller dielectric layer thicknesses at each reflection, resulting in a progressive blueshift of the reflectance spectrum. As the reflectance spectrum shifts, longer wavelengths of the initial bandgap cease to be omnidirectionally reflected and exit through the cladding, which narrows the photonic bandgap. A narrow transmission bandwidth is particularly desirable in hollow waveguide mid-infrared sensing schemes, where broadband light is coupled to the fiber and the analyte vapor is introduced into the hollow core to measure infrared absorption. We carried out sensing simulations using the absorption spectrum of isopropyl alcohol vapor to demonstrate the importance of narrow bandgap fibers in chemical sensing applications.

  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. The density matrix method in photonic bandgap and antiferromagnetic materials

    Science.gov (United States)

    Barrie, Scott B.

    In this thesis, a theory for dispersive polaritonic bandgap (DPBG) and photonic bandgap (PBG) materials is developed. An ensemble of multi-level nanoparticles, such as non-interacting two-, three- and four-level atoms doped in DPBG and PBG materials is considered. The optical properties of these materials such as spontaneous emission, line broadening, fluorescence and narrowing of the natural linewidth have been studied using the density matrix method. Numerical simulations for these properties have been performed for the DPBG materials SiC and InAs, and for a PBG material with a 20 percent gap-to-midgap ratio. When a three-level nanoparticle is doped into a DPBG material, it is predicted that one or two bound states exist when one or both resonance energies, respectively, lie in the bandgap. It is shown when a resonance energy lies below the bandgap, its spectral density peak weakens and broadens as the resonance energy increases to the lower band edge. For the first time it is predicted that when a nanoparticle's resonance energy lies above the bandgap, its spectral density peak weakens and broadens as the resonance energy increases. A relation is also found between spectral structure and gap-to-midgap ratios. The dressed states of a two-level atom doped into a DPBG material under the influence of an intense monochromatic laser field are examined. The splitting of the dressed state energies is calculated, and it is predicted that the splitting depends on the polariton density of states and the Rabi frequency of laser field. The fluoresence is also examined, and for the first time two distinct control processes are found for the transition from one peak to three peaks. It was previously known that the Rabi frequency controlled the Stark effect, but this thesis predicts that the local of the peak with respect to the optical bandgap can cause a transition from one to three peaks even with a weak Rabi frequency. The transient linewidth narrowing of PBG crystal

  12. 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.

  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. 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.

  16. 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].

  17. Electrically tunable Yb-doped fiber laser based on a liquid crystal photonic bandgap fiber device

    DEFF Research Database (Denmark)

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

    2010-01-01

    We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a tunable liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate ...

  18. 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.

  19. Lyapunov exponents for one-dimensional aperiodic photonic bandgap structures

    Science.gov (United States)

    Kissel, Glen J.

    2011-10-01

    Existing in the "gray area" between perfectly periodic and purely randomized photonic bandgap structures are the socalled aperoidic structures whose layers are chosen according to some deterministic rule. We consider here a onedimensional photonic bandgap structure, a quarter-wave stack, with the layer thickness of one of the bilayers subject to being either thin or thick according to five deterministic sequence rules and binary random selection. To produce these aperiodic structures we examine the following sequences: Fibonacci, Thue-Morse, Period doubling, Rudin-Shapiro, as well as the triadic Cantor sequence. We model these structures numerically with a long chain (approximately 5,000,000) of transfer matrices, and then use the reliable algorithm of Wolf to calculate the (upper) Lyapunov exponent for the long product of matrices. The Lyapunov exponent is the statistically well-behaved variable used to characterize the Anderson localization effect (exponential confinement) when the layers are randomized, so its calculation allows us to more precisely compare the purely randomized structure with its aperiodic counterparts. It is found that the aperiodic photonic systems show much fine structure in their Lyapunov exponents as a function of frequency, and, in a number of cases, the exponents are quite obviously fractal.

  20. Accurate modelling of fabricated hollow-core photonic bandgap fibers.

    Science.gov (United States)

    Fokoua, Eric Numkam; Sandoghchi, Seyed Reza; Chen, Yong; Jasion, Gregory T; Wheeler, Natalie V; Baddela, Naveen K; Hayes, John R; Petrovich, Marco N; Richardson, David J; Poletti, Francesco

    2015-09-07

    We report a novel approach to reconstruct the cross-sectional profile of fabricated hollow-core photonic bandgap fibers from scanning electron microscope images. Finite element simulations on the reconstructed geometries achieve a remarkable match with the measured transmission window, surface mode position and attenuation. The agreement between estimated scattering loss from surface roughness and measured loss values indicates that structural distortions, in particular the uneven distribution of glass across the thin silica struts on the core boundary, have a strong impact on the loss. This provides insight into the differences between idealized models and fabricated fibers, which could be key to further fiber loss reduction.

  1. Soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2009-01-01

    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......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...

  2. 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...

  3. Optical tuning of photonic bandgaps in dye-doped nematic liquid crystal photonic crystal fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard; Hermann, David Sparre;

    2005-01-01

    An all-optical modulator is demonstrated, which utilizes a pulsed 532 nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal. In order to investigate the time response of the LCPBG fiber device, a low-power CW probe...

  4. 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....

  5. Novel Photonic Bandgap Structure and Its Application in Amplifier

    Institute of Scientific and Technical Information of China (English)

    PANGYunbo; GAOBaoxin

    2003-01-01

    A novel compact photonic bandgap (PBG)structural element, which is etched in the ground plane of the microstrip line, is proposed in this paper. A forbid-den gap, which is about 200MHz wide, is measured at the center frequency of 8.6GHz. The measured results agree with finite difference time domain (FDTD) simulations. A harmonic-suppression amplifier is fabricated by utilizing this novel structural element. The suppression of the sec-ond order harmonic has been enhanced about 17dB when compared with a reference amplifier. Since no filters are needed and the structural element is etched in the ground plane, the whole circuit is compact.

  6. 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....... The optimization is based on continuous material interpolation functions between the refractive indices and is carried out by the method of moving asymptotes. An example illustrates the performance of the method where air and silica are redistributed around the core so that the overlap between the magnetic field...... distribution and the lossy silica material is reduced and the energy flow is increased 375% in the core. Simplified designs inspired from optimized geometry are presented, which will be easier to fabricate. The energy flow is increased up to almost 300% for these cases....

  7. Photonic bandgap properties of void-based body-centered-cubic photonic crystals in polymer.

    Science.gov (United States)

    Zhou, Guangyong; Ventura, Michael; Gu, Min; Matthews, Aaron; Kivshar, Yuri

    2005-06-13

    We report on the fabrication and characterization of void-based body-centered-cubic (bcc) photonic crystals in a solidified transparent polymer by the use of a femtosecond laser-driven microexplosion method. The change in the refractive index in the region surrounding the void dots that form the bcc structures is verified by presenting confocal microscope images, and the bandgap properties are characterized by using a Fourier transform infrared spectrometer. The effect of the angle of incidence on the photonic bandgaps is also studied. We observe multiple stop gaps with a suppression rate of the main gap of 47% for a bcc structure with a lattice constant of 2.77 microm, where the first and second stop gaps are located at 3.7 microm and 2.2 microm, respectively. We also present a theoretical approach to characterize the refractive index of the material for calculating the bandgap spectra, and confirm that the wavelengths of the observed bandgaps are in good correlation with the analytical predictions.

  8. Modeling of realistic cladding structures for photonic bandgap fibers

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Nielsen, Martin Dybendal

    2004-01-01

    . 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...

  9. Maximizing bandgaps in two-dimensional photonic crystals a variational algorithm

    CERN Document Server

    Paul, P; Paul, Prabasaj; Ndi, Francis C.

    2002-01-01

    We present an algorithm for the maximization of photonic bandgaps in two-dimensional crystals. Once the translational symmetries of the underlying structure have been imposed, our algorithm finds a global maximal (and complete, if one exists) bandgap. Additionally, we prove two remarkable results related to maximal bandgaps: the so-called `maximum contrast' rule, and about the location in the Brillouin zone of band edges.

  10. 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....

  11. 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....

  12. 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...... gradient of the refractive indices at room temperature. A bandgap tuning sensitivity of 27 nm/degrees C is achieved at room temperature. The insertion loss is estimated to be less than 0.5 dB and caused mainly by coupling loss between the index-guided mode and the bandgap-guided mode. (c) 2006 Optical...

  13. 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.

  14. Fast-light Assisted Four-Wave-Mixing in Photonic Bandgap

    CERN Document Server

    Feng, Cheng; Zhang, Liang; Liu, Jinmei; Zhan, Li

    2014-01-01

    Since the forward and backward waves are coupled with each other and a standing wave with no net propagation of energy is formed in the photonic bandgap, it is a commonsense of basic physics that, any kinds of effects associated with wave propagation including four-wave-mixing (FWM) are thought to be impossible. However, we lay great emphasis here on explaining that this commonsense could be broken under specific circumstances. In this article, we report with the first experimental observation of the energy conversion in the photonic bandgap into other channel via FWM. Owing to the phase manipulation by fast light effect in the photonic bandgap, we manage to achieve the phase-match condition and thus occurred FWM transfer energy into other channels outside the photonic bandgap efficiently. As one-dimensional photonic crystal, simulations on fiber Bragg grating (FBG) with and without fast light were conducted respectively, and an enhanced FWM in photonic bandgap of FBG was observed. The experimental result sho...

  15. Enhanced third-harmonic generation in photonic crystals at band-gap pumping

    Science.gov (United States)

    Yurchenko, Stanislav O.; Zaytsev, Kirill I.; Gorbunov, Evgeny A.; Yakovlev, Egor V.; Zotov, Arsen K.; Masalov, Vladimir M.; Emelchenko, Gennadi A.; Gorelik, Vladimir S.

    2017-02-01

    More than one order enhancement of third-harmonic generation is observed experimentally at band-gap pumping of globular photonic crystals. Due to a lateral modulation of the dielectric permittivity in two- and three-dimensional photonic crystals, sharp peaks of light intensity (light localization) arise in the media at the band-gap pumping. The light localization enhances significantly the nonlinear light conversion, in particular, third-harmonic generation, in the near-surface volume of photonic crystal. The observed way to enhance the nonlinear conversion can be useful for creation of novel compact elements of nonlinear and laser optics.

  16. Self-collimated waveguide bends and partial bandgap reflection of photonic crystals with parallelogram lattice.

    Science.gov (United States)

    Gao, Dingshan; Zhou, Zhiping; Citrin, David S

    2008-03-01

    The photonic crystal structure with parallelogram lattice, capable of bending a self-collimated wave with free angles and partial bandgap reflection, is presented. The equifrequency contours show that the direction of the collimation wave can be turned by tuning the angle between the two basic vectors of the lattice. Acute, right, and obtuse angles of collimating waveguide bends have been realized by arc lattices of parallelogram photonic crystals. Moreover, partial bandgap reflection of the parallelogram lattice photonic crystals is validated from the equifrequency contours and the projected band structures. A waveguide taper based on this partial bandgap reflection is also designed and proved to have above 85% transmittance over a very wide operating bandwidth of 180 nm.

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

    Institute of Scientific and Technical Information of China (English)

    LI Shu-Guang; ZHOU Hong-Song; YIN Guo-Bing

    2011-01-01

    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 kA of the improved fiber is from 7.2 to 8.5 in its first bandgap. The improved GLS HC-PCF with pitch of 4.2μm can transmit the lights with wavelengths ranging from 3.1μm to 3.7μm.%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 κA of the improved fiber is from 7.2 to 8.5 in its first bandgap.The improved GLS HC-PCF with pitch of 4.2μm can transmit the lights with wavelengths ranging from 3.1 μm to 3.7 μm.Photonic crystal fibers (PCFs) can be classified into total internal reflection PCFs and photonic bandgap (PBG) PCFs[1] Solid core PCFs are one kind of the total internal reflection PCFs;hollow-core PCFs (HC-PCFs) are a kind of typical PBG fibers.The conception of HC-PCFs was first proposed by Russel in 1991.[2] Later,it was theoretically demonstrated by Birks et al.[3] in 1995.A bandgap photonic crystal fiber was mde by Knight et al.[4] for the first time in 1998.On the basis of these works,the first HC-PCF was designed and made by Cregan et al.[5] in 1999.

  18. 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....

  19. 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.

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

    Science.gov (United States)

    Li, Shu-Guang; Zhou, Hong-Song; Yin, Guo-Bing

    2011-11-01

    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.

  1. 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.

  2. Reversed dispersion slope photonic bandgap fibers for broadband dispersion control in femtosecond fiber lasers.

    Science.gov (United States)

    Várallyay, Z; Saitoh, K; Fekete, J; Kakihara, K; Koshiba, M; Szipocs, R

    2008-09-29

    Higher-order-mode solid and hollow core photonic bandgap fibers exhibiting reversed or zero dispersion slope over tens or hundreds of nanometer bandwidths within the bandgap are presented. This attractive feature makes them well suited for broadband dispersion control in femtosecond pulse fiber lasers, amplifiers and optical parametric oscillators. The canonical form of the dispersion profile in photonic bandgap fibers is modified by a partial reflector layer/interface placed around the core forming a 2D cylindrical Gires-Tournois type interferometer. This small perturbation in the index profile induces a frequency dependent electric field distribution of the preferred propagating higher-order-mode resulting in a zero or reversed dispersion slope.

  3. 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...

  4. Millijoule Pulse Energy Second Harmonic Generation With Single-Stage Photonic Bandgap Rod Fiber Laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas Tanggaard

    2011-01-01

    In this paper, we demonstrate, for the first time, a single-stage Q-switched single-mode (SM) ytterbium-doped rod fiber laser delivering record breaking pulse energies at visible and UV light. We use a photonic bandgap rod fiber with a mode field diameter of 59μm based on a new distributed...

  5. 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.

  6. 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....

  7. On-chip tunable long-period grating devices based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Weirich, Johannes; Alkeskjold, Thomas Tanggaard;

    2009-01-01

    We design and fabricate an on-chip tunable long-period grating device by integrating a liquid crystal photonic bandgap fiber on silicon structures. The transmission axis of the device can be electrically rotated in steps of 45° as well as switched on and off with the response time in the millisec...

  8. 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...

  9. Transmission properties of hollow-core photonic bandgap fibers in relation to molecular spectroscopy

    DEFF Research Database (Denmark)

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

    2010-01-01

    The transmission properties of five types of hollow-core photonic bandgap fibers (HC-PBFs) are characterized in the telecom wavelength range around 1:5 μm. The variations in optical transmission are measured as a function of laser frequency over a 2GHz scan range as well as a function of time over...

  10. 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

  11. Tunable polarisation-maintaining filter based on liquid crystal photonic bandgap fibre

    DEFF Research Database (Denmark)

    Scolari, Lara; Olausson, Christina Bjarnal Thulin; Weirich, Johannes

    2008-01-01

    A tunable and polarisation-maintaining all-in-fibre filter based on a liquid crystal photonic bandgap fibre is demonstrated. Its polarisation extinction ratio reaches 14 dB at 1550 nm wavelength. Its spectral tunability range spans over 250 nm in the temperature range 30–70°C. The measured...

  12. Quantum information processing in localized modes of light within a photonic band-gap material

    CERN Document Server

    Vats, N; John, S; Vats, Nipun; Rudolph, Terry; John, Sajeev

    1999-01-01

    The single photon occupation of a localized field mode within an engineered network of defects in a photonic band-gap (PBG) material is proposed as a unit of quantum information (qubit). Qubit operations are mediated by optically-excited atoms interacting with these localized states of light as the atoms traverse the connected void network of the PBG structure. We describe conditions under which this system can have independent qubits with controllable interactions and very low decoherence, as required for quantum computation.

  13. 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℃.

  14. 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.

  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. Liquid crystal parameter analysis for tunable photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei;

    2010-01-01

    We investigate the tunability of splay-aligned liquid crystals for the use in solid core photonic crystal fibers. Finite element simulations are used to obtain the alignment of the liquid crystals subject to an external electric field. By means of the liquid crystal director field the optical per...

  18. 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 by in...

  19. Synthesis and photonic bandgap characterization of polymer inverse opals

    Energy Technology Data Exchange (ETDEWEB)

    Miguez, H.; Meseguer, F.; Lopez, C. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Ciencia de Materiales; Universidad Politecnica de Valencia (Spain). Centro Tecnologico de Ondas; Lopez-Tejeira, F.; Sanchez-Dehesa, J. [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica de la Materia Condensada

    2001-03-16

    Polymer inverse opals with long-range order have been fabricated and their photonic crystal behavior examined. Good agreement between band structure calculations and experiment is found. It is envisaged that these inverse opals could be used for the modification of the electronic properties of incorporated luminescent materials and as matrices for the synthesis of spherical colloidal particles. (orig.)

  20. Hollow core photonic bandgap fiber with microfluid-infiltrated air holes for slow-light propagation

    Science.gov (United States)

    Ren, Liyong; Liang, Jian; Yun, Maojin

    2012-10-01

    Slow light plays an important role in the fields of all-optical signal processing and integration photonics. It has shown many potential applications, such as realizing optical delay lines or buffers, enhancing linear and nonlinear light-matter interactions, as well as increasing the sensitivity of the interferometers and transducers. In this paper, hollow-core photonic bandgap fibers made from high index glasses are designed by infiltrating microfluid into the air-holes to tailor the fiber dispersion for slow-light propagation under low pulse distortion. In such a fiber made from Si material, group index ng~8 is obtained with a bandwidth up to 30 nm, where the group index fluctuation is restricted in ±10 % of the ng, while ng~6 is obtained with a bandwidth over 100 nm when the chalcogenide material is selected instead. Such a ±10 % criterion determines a regarded flatland region accordingly, and in this region the group velocity dispersion can be negligible. It is found that for the same fiber length the slow-light time delay in the photonic bandgap fiber is much larger as compared with that in the single mode fiber. This kind of photonic bandgap fiber may have many potential applications in short-distance fiber communications and delay lines.

  1. Low-Cost Production of Photonic Bandgap Materials Through Bubbling

    Science.gov (United States)

    2007-09-01

    that block copolymers could be self-assembled into 3-D periodic arrays with photonic properties. Instead of using solid spheres as templates, Imhof and...bubble stabilization. Imhof and Pine (11) used a technique called emulsion templating to produce an ordered ceramic foam with potential... Imhof and Pine (11), involves making a monodisperse emulsion with a ceramic precursor as the continuous phase. The emulsion technique could produce

  2. 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.

  3. Hollow-core photonic bandgap fibers for orbital angular momentum applications

    Science.gov (United States)

    Li, H.; Ren, G.; Gao, Y.; Zhu, B.; Wang, J.; Yin, B.; Jian, S.

    2017-04-01

    We present a study on the potential and challenges of guiding orbital angular momentum (OAM) modes in hollow-core photonic bandgap fibers (HC-PBGFs). Two 19-cell HC-PBGFs with different structural parameters are comparably investigated. The OAM mode properties in a 37-cell HC-PBGF are also discussed to explore the scalability of OAM states. Characteristics of vector modes and OAM modes are comprehensively analyzed with numerical simulations. The results show HC-PBGF with a larger core could effectively support more OAM modes with lower confinement loss and a larger effective area. In addition, HC-PBGF with a deeper and wider photonic bandgap is advantageous for achieving low crosstalk OAM transmission over a broader band-width. 19-cell HC-PBGFs could support OAM modes with purity beyond 0.9, and the value can be further improved by exploiting the 37-cell HC-PBGF.

  4. Impact of structural distortions on the performance of hollow-core photonic bandgap fibers

    OpenAIRE

    2014-01-01

    We present a generic model for studying numerically the performance of hollow-core photonic bandgap fibers (HC-PBGFs) with arbitrary cross-sectional distortions. Fully vectorial finite element simulations reveal that distortions beyond the second ring of air holes have an impact on the leakage loss and bandwidth of the fiber, but do not significantly alter its surface scattering loss which remains the dominant contribution to the overall fiber loss (providing that a sufficient number of rings...

  5. 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

    Abstract Soliton formation during dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap (HC-PBG) fiber is studied by numerical simulations. Long-pass filtering of the emerging frequency-shifted solitons is investigated with the objective...... at high powers. This allows a scaling of the output pulse energy toward the microjoule level. © 2009 Optical Society of America...

  6. 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.......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....

  7. 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 Ruddlesden–Popper phase of the layered perovskite structure. Based on screening criteria for the stability, bandgaps and band edge positions, we suggest 20 new materials for the light harvesting photo-electrode of a one-photon water splitting device and 5 anode materials for a two-photon device with silicon...

  8. Numerical simulation and analysis of losses in air-core plastic photonic bandgap fibers

    Institute of Scientific and Technical Information of China (English)

    Tieshan Guan; Mingyang Chen; Zhilong Zhang; Rongjin Yu

    2005-01-01

    @@ The loss properties of air-core plastic photonic bandgap fibers are analyzed by multipole method. Despite the relatively large absorption loss of plastics (PMMA), the contribution of material absorption loss can be reduced significantly through appropriate selection of operating wavelength, number of cladding air-hole rings, radius of air-core, and position of photonic band gap. The transmission loss in this type of fiber can be decreased by an order of magnitude in comparison with that of conventional plastic optical fiber.

  9. 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.

  10. 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.

  11. Stability and bandgaps of layered perovskites for one- and two-photon water splitting

    Science.gov (United States)

    Castelli, Ivano E.; María García-Lastra, Juan; Hüser, Falco; Thygesen, Kristian S.; Jacobsen, Karsten W.

    2013-10-01

    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 Ruddlesden-Popper phase of the layered perovskite structure. Based on screening criteria for the stability, bandgaps and band edge positions, we suggest 20 new materials for the light harvesting photo-electrode of a one-photon water splitting device and 5 anode materials for a two-photon device with silicon as photo-cathode. In addition, we explore a simple rule relating the bandgap of the perovskite to the number of octahedra in the layered structure and the B-metal ion. Finally, the quality of the GLLB-SC potential used to obtain the bandgaps, including the derivative discontinuity, is validated against G0W0@LDA gaps for 20 previously identified oxides and oxynitrides in the cubic perovskite structure.

  12. Novel photonic bandgap based architectures for quantum computers and networks

    Science.gov (United States)

    Guney, Durdu

    All of the approaches for quantum information processing have their own advantages, but unfortunately also their own drawbacks. Ideally, one would merge the most attractive features of those different approaches in a single technology. We envision that large-scale photonic crystal (PC) integrated circuits and fibers could be the basis for robust and compact quantum circuits and processors of the next generation quantum computers and networking devices. Cavity QED, solid-state, and (non)linear optical models for computing, and optical fiber approach for communications are the most promising candidates to be improved through this novel technology. In our work, we consider both digital and analog quantum computing. In the digital domain, we first perform gate-level analysis. To achieve this task, we solve the Jaynes-Cummings Hamiltonian with time-dependent coupling parameters under the dipole and rotating-wave approximations for a 3D PC single-mode cavity with a sufficiently high Q-factor. We then exploit the results to show how to create a maximally entangled state of two atoms and how to implement several quantum logic gates: a dual-rail Hadamard gate, a dual-rail NOT gate, and a SWAP gate. In all of these operations, we synchronize atoms, as opposed to previous studies with PCs. The method has the potential for extension to N-atom entanglement, universal quantum logic operations, and the implementation of other useful, cavity QED-based quantum information processing tasks. In the next part of the digital domain, we study circuit-level implementations. We design and simulate an integrated teleportation and readout circuit on a single PC chip. The readout part of our device can not only be used on its own but can also be integrated with other compatible optical circuits to achieve atomic state detection. Further improvement of the device in terms of compactness and robustness is possible by integrating with sources and detectors in the optical regime. In the analog

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. Hollow-core photonic bandgap fiber gas sensor with high sensitivity and fast response

    Science.gov (United States)

    Yang, Fan; Jin, Wei; Cao, Yingchun; Ho, Hoi Lut

    2014-05-01

    The effects of modal interference (MI) on the performance of hollow-core photonic bandgap fiber (HC-PBF) gas sensors are investigated. By optimizing mode launch, applying wavelength modulation with proper modulation parameters as well as appropriate digital signal processing, an estimated lower detection limit of drilling side-hole on the MI and response time are also studied. With a 62-cm long sensing HC-PBF drilled with multiple side-holes, an acetylene sensor with a lower detection limit of 11 ppmv and a recovery time of 2 minute is demonstrated.

  18. Photonic band-gap formation by optical-phase-mask lithography.

    Science.gov (United States)

    Chan, Timothy Y M; Toader, Ovidiu; John, Sajeev

    2006-04-01

    We demonstrate an approach for fabricating photonic crystals with large three-dimensional photonic band gaps (PBG's) using single-exposure, single-beam, optical interference lithography based on diffraction of light through an optical phase mask. The optical phase mask (OPM) consists of two orthogonally oriented binary gratings joined by a thin, solid layer of homogeneous material. Illuminating the phase mask with a normally incident beam produces a five-beam diffraction pattern which can be used to expose a suitable photoresist and produce a photonic crystal template. Optical-phase-mask Lithography (OPML) is a major simplification from the previously considered multibeam holographic lithography of photonic crystals. The diffracted five-beam intensity pattern exhibits isointensity surfaces corresponding to a diamondlike (face-centered-cubic) structure, with high intensity contrast. When the isointensity surfaces in the interference patterns define a silicon-air boundary in the resulting photonic crystal, with dielectric contrast 11.9 to 1, the optimized PBG is approximately 24% of the gap center frequency. The ideal index contrast for the OPM is in the range of 1.7-2.3. Below this range, the intensity contrast of the diffraction pattern becomes too weak. Above this range, the diffraction pattern may become too sensitive to structural imperfections of the OPM. When combined with recently demonstrated polymer-to-silicon replication methods, OPML provides a highly efficient approach, of unprecedented simplicity, for the mass production of large-scale three-dimensional photonic band-gap materials.

  19. 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...

  20. 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.

  1. Tunable narrow-bandpass filter based on an asymmetric photonic bandgap structure with a dual-mode liquid crystal.

    Science.gov (United States)

    Wang, Hsiao-Tsung; Timofeev, Ivan V; Chang, Kai; Zyryanov, Victor Ya; Lee, Wei

    2014-06-16

    A one-dimensional asymmetric photonic crystal with dual-frequency liquid crystal as a central defect layer was demonstrated. Such asymmetric structure was characterized by the dramatic increase in intensity of the electric field of light localized at the overlapped photonic bandgap edges, thereby enhancing the observed transmittance of the spectral windows originating from the defect layer. The defect layer was made of a dual-mode liquid crystal that exhibited not only electrical tunability and switchability but also optical bistability. Consequently, tunable and bistable defect modes can be realized in the photonic structure. This asymmetric photonic crystal structure is promising and should be further explored for photonic device applications.

  2. 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.

  3. 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.

  4. A Dual-Function All-in-Fiber Device Based on Negative Dielectric Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

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

    2008-01-01

    A dual-function all-in-fiber device based on negative dielectric liquid crystal photonic bandgap fibers is presented. This device can work both as an electrically tunable waveplate in the range 1520nm-1580nm, and as a polarimeter at 1310nm....

  5. Gamma irradiation of minimal latency Hollow-Core Photonic Bandgap Fibres

    CERN Document Server

    Olanterae, L; Richardson, D J; Vasey, F; Wooler, J P; Petrovich, M N; Wheeler, N V; Poletti, F; Troska, J

    2013-01-01

    Hollow-Core Photonic-Bandgap Fibres (HC-PBGFs) offer several distinct advantages over conventional fibres, such as low latency and radiation hardness; properties that make HC-PBGFs interesting for the high energy physics community. This contribution presents the results from a gamma irradiation test carried out using a new type of HC-PBGF that combines sufficiently low attenuation over distances that are compatible with high energy physics applications together with a transmission bandwidth that covers the 1550 nm region. The radiation induced attenuation of the HC-PBGF was two orders of magnitude lower than that of a conventional fibre during a 67.5 h exposure to gamma-rays, resulting in a radiation-induced attenuation of only 2.1 dB/km at an accumulated dose of 940 kGy.

  6. Photonic band-gap engineering in UV fiber gratings by the arc discharge technique.

    Science.gov (United States)

    Cusano, Andrea; Iadicicco, Agostino; Paladino, Domenico; Campopiano, Stefania; Cutolo, Antonello

    2008-09-29

    Localized heat treatments combined with local non-adiabatic tapering is proposed as suitable tool for the engineering of photonic band-gaps in UV-written fiber Bragg gratings (FBGs). In particular, here, we propose the use of the electric arc discharge to achieve localized defects along the FBG structure, however differently from previously reported works, we demonstrate how this post processing tool properly modified can be exploited to achieve the full control of the spectral characteristics of the final device. Also, we show how the suitable choice of the grating features and the correct selection of the defect geometry can be efficiently used to achieve interesting features for both communication and sensing applications.

  7. 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

  8. Impact of structural distortions on the performance of hollow-core photonic bandgap fibers.

    Science.gov (United States)

    Fokoua, Eric Numkam; Richardson, David J; Poletti, Francesco

    2014-02-10

    We present a generic model for studying numerically the performance of hollow-core photonic bandgap fibers (HC-PBGFs) with arbitrary cross-sectional distortions. Fully vectorial finite element simulations reveal that distortions beyond the second ring of air holes have an impact on the leakage loss and bandwidth of the fiber, but do not significantly alter its surface scattering loss which remains the dominant contribution to the overall fiber loss (providing that a sufficient number of rings of air holes (≥ 5) are used). We have found that while most types of distortions in the first two rings are generally detrimental, enlarging the core defect while keeping equidistant and on a circular boundary the glass nodes surrounding the core may produce losses half those compared to "idealized" fiber designs and with no penalty in terms of the transmission bandwidth.

  9. Tunable photonic band-gaps in one-dimensional photonic crystals containing linear graded index material

    Science.gov (United States)

    Singh, Bipin K.; Kumar, Pawan; Pandey, Praveen C.

    2014-12-01

    We have demonstrated control of the photonic band gaps (PBGs) in 1-D photonic crystals using linear graded index material. The analysis of PBG has been done in THz region by considering photonic crystals in the form of ten periods of second, third and fourth generation of the Fibonacci sequence as unit cell. The unit cells are constituted of two kinds of layers; one is taken of linear graded index material and other of normal dielectric material. For this investigation, we used a theoretical model based on transfer matrix method. We have obtained a large number of PBGs and their bandwidths can be tuned by changing the grading profile and thicknesses of linear graded index layers. The number of PBGs increases with increase in the thicknesses of layers and their bandwidths can be controlled by the contrast of initial and final refractive index of the graded layers. In this way, we provide more design freedom for photonic devices such as reflectors, filters, optical sensors, couplers, etc.

  10. Growth and Characterization of GaAs/AlGaAs Thue-Morse Quasicrystal Photonic Bandgap Structures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Gang; JIANG Xun-Ya; ZHU Cheng; GU Yi; LI Ai-Zhen; QI Ming; FENG Song-Lin

    2005-01-01

    @@ One-dimensional quasicrystal structures composed of Ⅲ-V semiconductor GaAs/AlGaAs multilayers in deterministic Thue-Morse (TM) sequences have been grown by using gas-source molecular beam epitaxy to investigate both the structural and the photonic bandgap properties. The x-ray measurements show that this aperiodic system exhibits obvious periodic spatial correlations, from which the precise thickness of the constitutive layers could be determined. Transmission and reflection measurements experimentally demonstrated plenty of photonic bandgaps with traditional or fractal features existing in those quasicrystal structures, which are in good agreement with the transfer matrix simulations. The diversity of this TM system makes it a good candidate for photonic device applications.

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

    Science.gov (United States)

    Men, H; Lee, K Y K; Freund, R M; Peraire, J; Johnson, S G

    2014-09-22

    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 techniques such as a simple approach to impose symmetry constraints. We also demonstrate a technique for robust topology optimization, in which some uncertainty is included in each voxel and we optimize the worst-case gap, and we show that the resulting band gaps have increased robustness to systematic fabrication errors.

  12. Photonic crystal film with three alternating layers for simultaneous R, G, B multi-mode photonic band-gaps.

    Science.gov (United States)

    Park, Byoungchoo; Kim, Mi-Na; Kim, Sun Woong; Ho Park, Jin

    2008-09-15

    We studied 1-dimensional (1-D) photonic crystal (PC) films with three alternating layers to investigate multi-mode photonic band-gaps (PBGs) at red, green, and blue color regions. From simulations, it was shown that PCs with three alternating layered elements of [a/b/c] structure have sharp PBGs at the three color regions with the central wavelengths of 459 nm, 527 nm, and 626 nm, simultaneously. Experimentally, it was proven that red, green, and blue PBGs were generated clearly by the PCs, which were made of multilayers of [SiO(2)/Ta(2)O(5)/TiO(2)], based on the simulation. It was also shown that the measured wavelengths of the PBGs corresponded exactly to those of the simulated results. Moreover, it was demonstrated that a 1-D PC of [a/b/c] structure can be used for making white organic light emitting devices (OLEDs) with improved color rendering index (CRI) for color display or lighting.

  13. 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

    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 and correspond...

  14. 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.

  15. Silica-glass contribution to the effective nonlinearity of hollow-core photonic band-gap fibers.

    Science.gov (United States)

    Hensley, Christopher J; Ouzounov, Dimitre G; Gaeta, Alexander L; Venkataraman, Natesan; Gallagher, Michael T; Koch, Karl W

    2007-03-19

    We measure the effective nonlinearity of various hollow-core photonic band-gap fibers. Our findings indicate that differences of tens of nanometers in the fiber structure result in significant changes to the power propagating in the silica glass and thus in the effective nonlinearity of the fiber. These results show that it is possible to engineer the nonlinear response of these fibers via small changes to the glass structure.

  16. Design of a second cyclotron harmonic gyrotron oscillator with photonic band-gap cavity

    Energy Technology Data Exchange (ETDEWEB)

    Liu Gaofeng; Chen Xiaoan; Tang Changjian, E-mail: angelchen765@163.com [College of Physical Science and Technology of Sichuan University, Chengdu 610065 (China)

    2011-07-27

    A photonic band-gap cavity (PBGC) gyrotron with a frequency of about 98 GHz is designed. Theoretical analyses and numerical calculations are made for the PBGC operating at fundamental and second cyclotron harmonic with a TE{sub 34} waveguide mode to demonstrate the beam-wave interaction. The results show that mode competition is successfully eliminated in the PBGC using mode selectivity and choosing the appropriate operating parameters. As a result, the second harmonic PBGC gyrotron operating at TE{sub 34} mode achieves a higher output efficiency than that of the fundamental. It is also demonstrated that, in the case of the chosen parameters for TE{sub 34} waveguide mode, the use of PBG structure in the second harmonic gyrotron brings about not only a lower operating B-field but also a weaker mode competition. The results show that the high-order electromagnetic mode can be developed to interact with the high cyclotron harmonic using the selectivity of the PBGC, which gives an encouraging outlook for the development of high-harmonic gyrotrons.

  17. Phase sensitivity of hollow-core photonic bandgap fiber to acoustic pressure

    Science.gov (United States)

    Pang, M.; Jin, W.

    2009-10-01

    Detection of acoustic pressure with optical fiber interferometers has been studied for many years1-3. The conventional solid silica fiber hydrophone was sufficient to prove the concept; however, it has low acoustic sensitivity. This is because 1) the silica glass material has relatively high Young's modulus, which makes the conventional fiber incompressible; 2) the refractive index change resulted from fiber strain has opposite sign with respective to the strain term and hence compromises the acoustic sensitivity. In a hollow-core photonic bandgap fiber (PBF), the fundamental mode is almost entirely confined to the air core, the effective Young's modulus of fiber is expected to be reduced and the undesirable "negative" index effect is anticipated to be greatly decreased. We experimentally measured that the phase sensitivity of the commercial HC-1550-02 PBF and found it is improved by a factor of 15dB compared to a conventional (HNSM-155) single mode fiber, which agrees well with theoretical prediction.

  18. A 158 fs 5.3 nJ fiber-laser system at 1 mu m using photonic bandgap fibers for dispersion control and pulse compression

    DEFF Research Database (Denmark)

    Nielsen, C.K.; Jespersen, Kim Giessmann; Keiding, S.R.

    2006-01-01

    We demonstrate a 158 fs 5.3 nJ mode-locked laser system based on a fiber oscillator, fiber amplifier and fiber compressor. Dispersion compensation in the fiber oscillator was obtained with a solid-core photonic bandgap (SC-PBG) fiber spliced to standard fibers, and external compression is obtained...... with a hollow-core photonic bandgap (HC-PBG) fiber....

  19. 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....

  20. 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...... rules on how to combine two cubic perovskites to generate a new combination with a larger or smaller bandgap compared with the constituent structures. Those rules are based on the type of orbitals involved in the conduction bands and on the size of the two cubic bandgaps. We also see that a change...

  1. 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.

  2. 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.

  3. Theoretical investigation of band-gap and mode characteristics of anti-resonance guiding photonic crystal fibres

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

    With the full-vector plane-wave method (FVPWM) and the full-vector beam propagation method (FVBPM), the dependences of the band-gap and mode characteristics on material index and cladding structure parameter in anti-resonance guiding photonic crystal fibres (ARGPCFs) are sufficiently analysed. An ARGPCF operating in the near-infrared wavelength is shown. The influences of the high index cylinders, glass interstitial apexes and silica structure on the characteristics of band-gaps and modes are deeply investigated. The equivalent planar waveguide theory is used for analysing such an ARGPCF filled by the isotropic materials, and the resonance and the anti-resonance characteristics can be well predicted.

  4. Photon absorption and photocurrent in solar cells below semiconductor bandgap due to electron photoemission from plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Uskov, Alexander; Gritti, Claudia;

    2014-01-01

    We model the electron photoemission frommetal nanoparticles into a semiconductor in a Schottky diode with a conductive oxide electrode hosting the nanoparticles. We show that plasmonic effects in the nanoparticles lead to a substantial enhancement in photoemission compared with devices with conti....... Such structure can form the dais of the development of plasmonic photoemission enhanced solar cells....... with continuous metal films. Optimally designed metal nanoparticles can provide an effectivemechanismfor the photon absorption in the infrared range below the semiconductor bandgap, resulting in the generation of a photocurrent in addition to the photocurrent from band-to-band absorption in a semiconductor...

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

    OpenAIRE

    2016-01-01

    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 reflec...

  6. 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.

  7. Management of the high-order mode content in large (40 microm) core photonic bandgap Bragg fiber laser.

    Science.gov (United States)

    Gaponov, D A; Février, S; Devautour, M; Roy, P; Likhachev, M E; Aleshkina, S S; Salganskii, M Y; Yashkov, M V; Guryanov, A N

    2010-07-01

    Very large-mode-area Yb(3+)-doped single-mode photonic bandgap (PBG) Bragg fiber oscillators are considered. The transverse hole-burning effect is numerically modeled, which helps properly design the PBG cladding and the Yb(3+)-doped region for the high-order mode content to be carefully controlled. A ratio of the Yb(3+)-doped region diameter to the overall core diameter of 40% allows for single-mode emission, even for small spool diameters of 15 cm. Such a fiber was manufactured and subsequently used as the core element of a cw oscillator. Very good beam quality parameter M(2)=1.12 and slope efficiency of 80% were measured. Insensitivity to bending, exemplified by the absence of temporal drift of the beam, was demonstrated for curvature diameter as small as 15 cm.

  8. In vivo imaging of the morphology and changes in pH along the gastrointestinal tract of Japanese medaka by photonic band-gap hydrogel microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xuemin [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lei, Ngai-Yu; Hu, Peng [Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lei, Zhang; Ong, Daniel Hock-Chun [Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong (China); Ge, Xuewu [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhicheng, E-mail: zczhang@ustc.edu.cn [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Lam, Michael Hon-Wah, E-mail: bhmhwlam@cityu.edu.hk [Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123 (China); Centre for Functional Photonics, Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-07-17

    Graphical abstract: -- Highlights: •Fabrication of pH-responsive photonic colloidal crystalline microspheres. •Specific photonic band-gap responses occurred in the pH range of 4–5. •Remarkably low in vivo toxicity to Japanese medaka (Oryzia latipes). •In vivo imaging of the morphology and pH along GI tract of Japanese medaka. •Demonstrates bio-imaging potentials of stimuli-responsive photonic materials. -- Abstract: Colloidal crystalline microspheres with photonic band-gap properties responsive to media pH have been developed for in vivo imaging purposes. These colloidal crystalline microspheres were constructed from monodispersed core–shell nano-size particles with poly(styrene-co-acrylic acid) (PS-co-PAA) cores and poly(acrylic acid-co-N-isopropylacrylamide) (PAA-co-PNIPAM) hydrogel shells cross-linked by N,N′-methylenebisacrylamide. A significant shift in the photonic band-gap properties of these colloidal crystalline microspheres was observed in the pH range of 4–5. This was caused by the discontinuous volume phase transition of the hydrogel coating, due to the protonation/deprotonation of its acrylic acid moieties, on the core–shell nano-sized particles within the microspheres. The in vivo imaging capability of these pH-responsive photonic microspheres was demonstrated on a test organism – Japanese medaka, Oryzia latipes – in which the morphology and change in pH along their gastrointestinal (GI) tracts were revealed under an ordinary optical microscope. This work illustrates the potential of stimuli-responsive photonic band-gap materials in tissue-/organ-level in vivo bio-imaging.

  9. 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.

  10. Hypersonic modulation of light in three-dimensional photonic and phononic band-gap materials.

    Science.gov (United States)

    Akimov, A V; Tanaka, Y; Pevtsov, A B; Kaplan, S F; Golubev, V G; Tamura, S; Yakovlev, D R; Bayer, M

    2008-07-18

    The elastic coupling between the a-SiO2 spheres composing opal films brings forth three-dimensional periodic structures which besides a photonic stop band are predicted to also exhibit complete phononic band gaps. The influence of elastic crystal vibrations on the photonic band structure has been studied by injection of coherent hypersonic wave packets generated in a metal transducer by subpicosecond laser pulses. These studies show that light with energies close to the photonic band gap can be efficiently modulated by hypersonic waves.

  11. 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.

  12. Some observations on hyperuniform disordered photonic bandgap materials, from microwave scale study to infrared scale study

    Science.gov (United States)

    Tsitrin, Sam; Nahal, Geev; Florescu, Marian; Man, Weining; San Francisco State University Team; University of Surrey Team

    2015-03-01

    A novel class of disordered photonic materials, hyperuniform disordered solids (HUDS), attracted more attention. Recently they have been experimentally proven to provide complete photonic band gap (PBG) when made with Alumina or Si; as well as single-polarization PBG when made with plastic with refract index of 1.6. These PBGs were shown to be real energy gaps with zero density of photonic states, instead of mobility gaps of low transmission due to scattering, etc. Using cm-scale samples and microwave experiments, we reveal the nature of photonic modes existing in these disordered materials by analyzing phase delay and mapping field distribution profile inside them. We also show how to extend the proof-of-concept microwave studies of these materials to proof-of-scale studies for real applications, by designing and fabricating these disordered photonic materials at submicron-scale with functional devices for 1.55 micron wavelength. The intrinsic isotropy of the disordered structure is an inherent advantage associated with the absence of limitations of orientational order, which is shown to provide valuable freedom in defect architecture design impossible in periodical structures. NSF Award DMR-1308084, the University of Surrey's FRSF and Santander awards.

  13. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Christina A.; Zeuner, Franziska; Bader, Manuel H. W.; Zentgraf, Thomas; Meier, Cedrik [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), Universität Paderborn, Warburger Str. 100, 33098 Paderborn (Germany)

    2015-12-07

    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/SiO{sub 2} microdisk devices exhibit strong nonlinear response when excited with NIR pulses (λ ≈ 1060 nm). In addition, we show that the ZnO/SiO{sub 2} 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.

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

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; 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...

  16. Coupled-mode theory for photonic band-gap inhibition of spatial instabilities.

    Science.gov (United States)

    Gomila, Damià; Oppo, Gian-Luca

    2005-07-01

    We study the inhibition of pattern formation in nonlinear optical systems using intracavity photonic crystals. We consider mean-field models for singly and doubly degenerate optical parametric oscillators. Analytical expressions for the new (higher) modulational thresholds and the size of the "band gap" as a function of the system and photonic crystal parameters are obtained via a coupled-mode theory. Then, by means of a nonlinear analysis, we derive amplitude equations for the unstable modes and find the stationary solutions above threshold. The form of the unstable mode is different in the lower and upper parts of the band gap. In each part there is bistability between two spatially shifted patterns. In large systems stable wall defects between the two solutions are formed and we provide analytical expressions for their shape. The analytical results are favorably compared with results obtained from the full system equations. Inhibition of pattern formation can be used to spatially control signal generation in the transverse plane.

  17. Reduction of Refractive Index Contrast Threshold for Photonic Band-Gap in Square Lattices

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Feng; HUANG Yi-Dong; ZHANG Wei; PENG Jiang-De

    2005-01-01

    @@ The threshold of refractive index contrast (RIC) to open a photonic band gap can be reduced by symmetry breaking. For the case of square lattice composed by dielectric cylinders, the absolute band gap is demonstrated by inserting small rods in the centre of the lattices, and the threshold RIC is reduced to 3.8. As for the square lattices composed by air holes in dielectric, the minimal RIC required for an absolute band gap decreases to 2.20.

  18. Simple expressions for the maximum omnidirectional bandgap of bilayer photonic crystals.

    Science.gov (United States)

    Hsueh, W J; Wun, S J

    2011-05-01

    We propose three dimensionless approximate expressions to predict the thickness filling factor, gap center, and gap width of the maximum omnidirectional gap (MODG) for various refractive indices in one-dimensional photonic crystals. These expressions are simple and do not include trigonometric or inverse trigonometric functions. It is easy to obtain the MODG from given refractive indices but also to estimate the refractive indices from the MODG based on the results.

  19. Complete Band-Gap in Two-Dimensional Quasiperiod Photonic Crystals with Hollow Cylinders

    Institute of Scientific and Technical Information of China (English)

    FENG Zhi-Fang; FENG Shuai; REN Kun; LI Zhi-Yuan; CHENG Bing-Ying; ZHANG Dao-Zhong

    2005-01-01

    @@ The transmission properties of quasiperiodic photonic crystals (QPCs) based on the random square-triangle tilingsystem are investigated by the multiple scattering method. The hollow cylinders are introduced in our calculation. It is found that QPCs with hollow cylinders also possess a complete band gap common to s- and p-polarized waves when the inner radius of hollow cylinders is larger than a certain value. The QPCs possessing the complete band gap can be applied to the fields of light emitting, wave-guides, optical filters, high-Q resonators and antennas.

  20. Enhanced four-wave mixing via photonic bandgap coupled defect resonances.

    Science.gov (United States)

    Blair, S

    2005-05-16

    Frequency conversion efficiency via four-wave mixing in coupled 1-D photonic crystal defect structures is studied numerically. In structures where all interacting frequencies coincide with intraband defect resonances, energy conversion efficiencies greater than 5% are predicted. Because the frequency spacings are determined by the free-spectral range, thereby requiring long defects for small spacings using intraband resonances, four-wave mixing using coupled-defect miniband resonances in more compact structures is also studied. Conversion efficiencies of greater than 1% are obtained in this case.

  1. 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...

  2. A new modality for minimally invasive CO2 laser surgery: flexible hollow-core photonic bandgap fibers.

    Science.gov (United States)

    Shurgalin, Max; Anastassiou, Charalambos

    2008-01-01

    Carbon dioxide (CO2) lasers have become one of the most common surgical lasers due to excellent tissue interaction properties that offer precise control of cutting and ablation depth, minimal thermal damage to surrounding tissue, and good hemostasis. However, realization of the benefits offered by using surgical CO2 lasers in many endoscopic, minimally invasive surgical procedures has been inhibited by the absence of reliable, flexible fiber laser beam delivery systems. Recently, novel hollow-core photonic bandgap optical fibers for CO2 lasers were developed that offer high flexibility and mechanical robustness with good optical performance under tight bends. These fibers can be used through rigid and flexible endoscopes and various handpieces and will allow surgeons to perform delicate and precise laser surgery procedures in a minimally invasive manner. This paper describes the basic design of laser beam delivery system, different surgical fiber designs and their characteristics, and usage with existing surgical CO2 laser models. A few examples of successful CO2 laser surgeries performed with these fibers are presented.

  3. Temperature dependence of beat-length and confinement loss in an air-core photonic band-gap fiber

    Science.gov (United States)

    Xu, Zhenlong; Li, Xuyou; Hong, Yong; Liu, Pan; Yang, Hanrui; Ling, Weiwei

    2016-05-01

    The temperature dependence of polarization-maintaining (PM) property and loss in a highly-birefringent air-core photonic band-gap fiber (PBF) is investigated. The effects of temperature variation on the effective index, beat-length and confinement loss are studied numerically by using the full-vector finite element method (FEM). It is found that, the PM property of this PBF is insensitive to the temperature, and the temperature-dependent beat-length coefficient can be as low as 2.86×10-8 m/°C, which is typically 200 times less than those of conventional panda fibers, the PBF has a stable confinement loss of 0.01 dB/m over the temperature range of -30 to 20 °C for the slow axis at the wavelength of 1.55 μm. The PBF with ultra-low temperature-dependent PM property and low loss can reduce the thermally induced polarization instability apparently in interferometric applications such as resonant fiber optic gyroscope (RFOG), optical fiber sensors, and so on.

  4. Photonic band-gap properties for two-component slow light

    CERN Document Server

    Ruseckas, J; Juzeliunas, G; Unanyan, R G; Otterbach, J; Fleischhauer, M

    2011-01-01

    We consider two-component "spinor" slow light in an ensemble of atoms coherently driven by two pairs of counterpropagating control laser fields in a double tripod-type linkage scheme. We derive an equation of motion for the spinor slow light (SSL) representing an effective Dirac equation for a massive particle with the mass determined by the two-photon detuning. By changing the detuning the atomic medium acts as a photonic crystal with a controllable band gap. If the frequency of the incident probe light lies within the band gap, the light tunnels through the sample. For frequencies outside the band gap, the transmission probability oscillates with increasing length of the sample. In both cases the reflection takes place into the complementary mode of the probe field. We investigate the influence of the finite excited state lifetime on the transmission and reflection coefficients of the probe light. We discuss possible experimental implementations of the SSL using alkali atoms such as Rubidium or Sodium.

  5. 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...

  6. 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...

  7. 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.

  8. 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

  9. All fiber M-Z interferometer for high temperature sensing based on a hetero-structured cladding solid-core photonic bandgap fiber.

    Science.gov (United States)

    Hu, Xiongwei; Shen, Xiang; Wu, Jianjun; Peng, Jinggang; Yang, Lvyun; Li, Jinyan; Li, Haiqin; Dai, Nengli

    2016-09-19

    We proposed and experimentally demonstrated a high temperature fiber sensor using a hetero-structured cladding solid-core photonic bandgap fiber (HCSC-PBGF) for the first time to our knowledge. A hetero-structured cladding solid-core photonic bandgap fiber is designed and fabricated that supports vibrant core mode and cladding mode transmission. Then, an all fiber M-Z interference sensor is constructed by splicing single mode fiber at both ends of HCSC-PBGF without any other micromachining. The transmission characteristics of HCSC-PBGF are analyzed with a full-vector beam propagation method and a full-vector finite element method, and the simulation results are consistent with experiment results. The sensitivity of this fiber sensor is as high as 0.09 nm/°C when operating from room temperature to 1000 °C, and the fringe contrast keeps stable and clear. It is obvious that this all fiber sensor will have great application prospects in fiber sensing with the advantages of a compact structure, high sensitivity, and cost-effectiveness.

  10. 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.

  11. 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.

  12. Non-resonant wavelength modulation saturation spectroscopy in acetylene-filled hollow-core photonic bandgap fibres applied to modulation-free laser diode stabilisation.

    Science.gov (United States)

    Pineda-Vadillo, Pablo; Lynch, Michael; Charlton, Christy; Donegan, John F; Weldon, Vincent

    2009-12-07

    In this paper the application of Wavelength Modulation (WM) techniques to non-resonant saturation spectroscopy in acetylene-filled Hollow-Core Photonic Bandgap Fibres (HC-PBFs) and modulation-free Laser Diode (LD) frequency stabilisation is investigated. In the first part WM techniques are applied to non-resonant pump-probe saturation of acetylene overtone rotational transitions in a HC-PBF. A high-power DFB chip-on-carrier mounted LD is used in conjunction with a tuneable External Cavity Laser (ECL) and the main saturation parameters are characterized. In the second part a novel feedback system to stabilize the DFB emission wavelength based on the WM saturation results is implemented. Modulation-free locking of the DFB laser frequency to the narrow linewidth saturation feature is achieved for both constant and variable LD temperatures.

  13. 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

    2015-11-06

    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.

  14. 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.

  15. 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....

  16. Design of single-polarization coupler based on dual-core photonic band-gap fiber implied in resonant fiber optic gyro

    Science.gov (United States)

    Xu, Zhenlong; Li, Xuyou; Zhang, Chunmei; Ling, Weiwei; Liu, Pan; Xia, Linlin; Yang, Hanrui

    2016-12-01

    A novel (to our knowledge) type of single-polarization (SP) coupler based on a dual-core photonic band-gap fiber (PBF) is proposed. The effects of structure parameters on the performance of this coupler are studied numerically based on the full vector finite element method (FEM). Finally, an optimal design with a length of 0.377 mm at the wavelength of 1.55 μm is achieved, and its implication in PBF-based fiber ring resonator (FRR), the effect of angular misalignment on the SP coupler are analyzed as well. When the SP coupler is incorporated into a PBF-based FRR, it functions as the power splitter and the polarizer simultaneously, and can extinct the secondary eigenstate of polarization (ESOP) propagating in the FRR. The mode field of SP coupler can match with the polarization-maintaining (PM) PBF with ultra-low temperature sensitivity proposed in previous study, and an all PM-PBF based FRR can be established, which is of great significance in suppressing the temperature-related polarization fluctuation and improving the long-term stability for RFOG, and the SP coupler has high angular misalignment tolerance as well.

  17. Applications and Technologies of All-Solid State Blue Laser

    Institute of Scientific and Technical Information of China (English)

    JING Zhuo; XUE Jun-wen; JIA Fu-qiang; ZHENG Quan; YE Zi-qing

    2006-01-01

    @@ 1 Introduction Along with the matureness of laser diode (LD) manufacturing technology, the performance of LD has been improved greatly since 1980s, so various kinds of laser devices based on LD have been developed rapidly, especially the all-solid state lasers. After early experiments and researches, the all-solid state lasers have been commercialized successfully.

  18. 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.

  19. 结构参数对二维Archimedes A7晶格光子晶体禁带的影响%Effects of structure parameters on the bandgap of two dimensional Archimedes A7 photonic crystals

    Institute of Scientific and Technical Information of China (English)

    杨毅彪; 王伟军; 费宏明; 梁伟; 王云才

    2012-01-01

    利用平面波展开法对空气背景中介质圆柱和方柱构造的二维Archimedes A7晶格光子晶体的禁带结构随介质折射率、填充比的变化关系进行了研究,并进一步计算了介质方柱的旋转角度对完全光子禁带宽度的影响.研究发现,介质圆柱构造的Archimedes A7晶格结构在介质柱折射率最低为n=2.40时出现完全光子禁带,当n=2.60时禁带宽度达到最大值.介质方柱构造的Archimedes A7晶格结构在介质柱折射率n=3.80时完全禁带宽度达到最大值,且随着折射率的增加禁带宽度变化很小;在介质方柱折射率恒定情况下,其最大禁带宽度与旋转角度无关,但旋转后出现完全禁带的填充比范围明显扩大.%Plane wave expansion method is introduced to simulate the band structures of two-dimensional photonic crystals made of Archimedes A7 lattice of circular and square dielectric rod in air. The bandgaps of Archimedes A7 lattice with dielectric rods is also discussed as functions of the refractive index, filling fraction and rotation angle. The results show that the complete bandgap can be obtained when the refractive index is greater than 2.40. The width of complete bandgap reaches the maximum when the dielectric refractive index of the circular rod is equal to 2.60. For the Archimedes A7 lattice of square dielectric rod, the complete bandgap reaches the maximum when the dielectric refractive index equals 3. 80. The maximum complete bandgap changes in a narrow range as the refractive index increases. When the rotation angle of the square dielectric rods changes, the maximum bandgap keeps constant for a fixed refractive index. However after the change of rotation angle, the complete bandgap appears in a large scale of the filling fraction.

  20. Subpicosecond pulse generation from an all solid-state laser

    Science.gov (United States)

    Keen, S. J.; Ferguson, A. I.

    1989-11-01

    An all-solid-state (holosteric) laser source which produces subpicosecond pulses at 1.4 microns is described. The system consists of a diode laser pumped Nd:YAG laser which is frequency-modulated (FM) mode-locked and Q-switched at 1.32 microns. In continuous wave operation the laser produces pulses of 19 ps while simultaneous Q-switching and mode-locking result in 30 ps pulses being contained in a Q-switched envelope of energy 2.1 microJ. The output of the laser, when passed through a 1 km single-mode optical fiber, produces a spectrally broad Raman signal with its peak at 1.4 microns and the overall conversion efficiency at 12 percent. The pulse duration at 1.4 microns has been measured to be 280 fs. This is the first time that subpicosecond light pulses have been generated by an all-solid-state laser system.

  1. PVD materials for electrochromic all-solid-state devices

    Science.gov (United States)

    Ottermann, Clemens R.; Segner, Johannes G.; Bange, Klaus

    1992-11-01

    The electrochromic properties of all solid state devices (ASSDs) are strongly defined by thin film materials used as well as the method of deposition. Various thin film materials deposited by evaporation and sputtering are described serving as electrode, reflector, electrolyte, storage medium, or electrochromic film in ASSD. The impact of process parameters upon the device functionality is shown. In addition, the long-term stability of ASSDs for the different thin film systems is reported.

  2. 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...

  3. 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.

  4. Multi-Line Fit Model for the Detection of Methane at ν2 + 2ν3 Band using Hollow-Core Photonic Bandgap Fibres

    Directory of Open Access Journals (Sweden)

    Ana M. Cubillas

    2009-01-01

    Full Text Available Hollow-core photonic bandgap fibres (HC-PBFs have emerged as a novel technology in the field of gas sensing. The long interaction pathlengths achievable with these fibres are especially advantageous for the detection of weakly absorbing gases. In this work, we demonstrate the good performance of a HC-PBF in the detection of the ν2 + 2ν3 band of methane, at 1.3 μm. The Q-branch manifold, at 1331.55 nm, is targeted for concentration monitoring purposes. A computationally optimized multi-line model is used to fit the Q-branch. Using this model, a detection limit of 98 ppmv (parts per million by volume is estimated.

  5. Tunable three photonic band-gaps coherently induced in one-dimensional cold atomic lattices%一维冷原子晶格中相干诱导三光子带隙

    Institute of Scientific and Technical Information of China (English)

    巴诺; 王磊; 张岩

    2014-01-01

    基于电磁感应透明技术,将相干耦合的Tripod型原子俘获在一维光晶格中并使其呈高斯型分布,由于介质的折射率被一维光晶格周期性调制,从而实现动态调控的三光子带隙结构。通过求解光场与原子相互作用密度矩阵方程以及光波在周期性介质中散射的传输矩阵方程,计算出探测场在相干驱动介质中的稳态反射谱和透射谱。计算结果表明:光子带隙的位置、宽度以及反射率可以通过改变两个耦合场的失谐、强度和几何布拉格失谐来调谐。%Using the technique of electromagnetically induced transparency, three photonic bandgaps can be established and manipulated at any time due to the refraction modulated periodically by the one-dimensional optical lattice in a tripod atomic system which is trapped in a one-dimensional optical lattice with a Gaussian density distribution. Using the density-matrix equations to describe the interaction between laser and atoms and the transfer-matrix equation to describe the scattering of light waves in periodic media, we can obtain the steady reflection and transmission spectra. It can be found that the position and width as well as the reflectivity of the photonic band-gap could be tuned by changing the detunings and intensities of the coupling fields and the geometric Bragg detuning.

  6. 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...

  7. Highly flexible and all-solid-state paperlike polymer supercapacitors.

    Science.gov (United States)

    Meng, Chuizhou; Liu, Changhong; Chen, Luzhuo; Hu, Chunhua; Fan, Shoushan

    2010-10-13

    In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H(2)SO(4)-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 μA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

  8. All-solid-state Z-scheme photocatalytic systems.

    Science.gov (United States)

    Zhou, Peng; Yu, Jiaguo; Jaroniec, Mietek

    2014-08-06

    The current rapid industrial development causes the serious energy and environmental crises. Photocatalyts provide a potential strategy to solve these problems because these materials not only can directly convert solar energy into usable or storable energy resources but also can decompose organic pollutants under solar-light irradiation. However, the aforementioned applications require photocatalysts with a wide absorption range, long-term stability, high charge-separation efficiency and strong redox ability. Unfortunately, it is often difficult for a single-component photocatalyst to simultaneously fulfill all these requirements. The artificial heterogeneous Z-scheme photocatalytic systems, mimicking the natural photosynthesis process, overcome the drawbacks of single-component photocatalysts and satisfy those aforementioned requirements. Such multi-task systems have been extensively investigated in the past decade. Especially, the all-solid-state Z-scheme photocatalytic systems without redox pair have been widely used in the water splitting, solar cells, degradation of pollutants and CO2 conversion, which have a huge potential to solve the current energy and environmental crises facing the modern industrial development. Thus, this review gives a concise overview of the all-solid-state Z-scheme photocatalytic systems, including their composition, construction, optimization and applications.

  9. 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.

  10. Characterization of an all solid-state electrochromic window

    Science.gov (United States)

    Tonazzi, Juan C. L.; Valla, Bruno; Macedo, Marcelo A.; Baudry, Paul; Aegerter, Michel A.; Martins Rodrigues, Ana C.; Bulhoes, Luis O.

    1990-11-01

    Sol-gel cerium - titanium oxide layers present potential application as transparent counter-electrode (ion storage layer) in electrochromic windows and mirrors using lithium conducting electrolyte and W03 electrochromic coating. The precursor sol, prepared by mixing Ti(OPri)4 and Ce(N03)6 (NH4)2 in ethanol, is initially dark red and becomes transparent after a few days aging indicating the presence of Ce3 complexes. The layers have been obtained by dip coating technique and heat treated at 4509C during 15 minutes.They have been characterized by XRD, SIMS, optical absorption and electrochemical techniques; it is shown that the electrochemical reaction corresponds to a reversible insertion-extraction oflithium ions within a Ti02 amorphous film containing small Ce02 crystallites. At low sweep frequencies the process is controlled by a diffusion mechanism (DLi ~= 6.4 lOl2cm2/s at 259C). Characterizations of an all solid state electrochromic window/glass/JTO/ W03/ POE-Li N (502 CF3)2 1 Ti02 - Ce02 I ITO I glass I are also presented.

  11. A compact, all solid-state LC high voltage generator.

    Science.gov (United States)

    Fan, Xuliang; Liu, Jinliang

    2013-06-01

    LC generator is widely applied in the field of high voltage generation technology. A compact and all solid-state LC high voltage generator based on saturable pulse transformer is proposed in this paper. First, working principle of the generator is presented. Theoretical analysis and circuit simulation are used to verify the design of the generator. Experimental studies of the proposed LC generator with two-stage main energy storage capacitors are carried out. And the results show that the proposed LC generator operates as expected. When the isolation inductance is 27 μH, the output voltage is 1.9 times larger than the charging voltage on single capacitor. The multiplication of voltages is achieved. On the condition that the primary energy storage capacitor is charged to 857 V, the output voltage of the generator can reach to 59.5 kV. The step-up ratio is nearly 69. When self breakdown gas gap switch is used as main switch, the rise time of the voltage pulse on load resistor is 8.7 ns. It means that the series-wound inductance in the discharging circuit is very small in this system. This generator can be employed in two different applications.

  12. An all-solid-state CO2 laser driver

    Science.gov (United States)

    Birx, Daniel

    1991-03-01

    New, all-solid-state pulse generators are described which meet military requirements for an efficient, reliable pulsed power source to drive a space based CO2 laser. These SCR-commutated, nonlinear magnetic pulse compressors are fully-compatible with the present Spectra Technologies laser head design planned for use on LOWKATER. By employing SCRs rather than thyratron commutators, these pulsers should provide a significant increase in reliability over the current generation of pulsed power drivers. The first pulser which was designed and constructed was denoted COLD-I. COLD-I was designed to meet the original LOWKATER specifications and delivered at 150 joule, 20 kV pulse into a laser load at 10 to 20 Hz repetition rate. The second pulser, denoted COLD-II, was designed to provide a 45 joule, 500 nsec duration pulse at a voltage of 20 kV and a repetition rate of 1 kHz peak and 50 to 100 Hz average. The electrical efficiency was measured to be 80 percent with an input drive of 500 VDC. This pulse served as a design verification testbed for a third pulser, presently designed but not constructed and denoted COLD-III. COLD-III would be capable of producing 36 joules at the same pulse length and repetition rate at voltages of 20 kV. The Phase-II effort was a high risk, high payoff effort aimed at developing a light weight, high reliability RF power source for advanced RF CO2 laser heads under development. COLD-IV a Branched Magnetic RF Nonlinear Magnetic Pulse Compressor was built as a bread

  13. All-Solid-State Four-Color Laser

    Energy Technology Data Exchange (ETDEWEB)

    Gosnell, T.R.; Xie, P.

    1999-06-03

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this project is to develop a solid state laser that produces visible output wavelengths, including the commercially compelling blue wavelength. The basic architecture of the device consists of a single-mode optical fiber doped with Pr{sup 3+} and Yb{sup 3+} ions. When the ions are simultaneously pumped with a near infrared laser (860 nm), complex energy transfer processes involving multiple excited ions leads to population of a high-lying energy level of Pr{sup 3+}. Results include the demonstration of the existence of a photon avalanche mechanism responsible for creation of the population inversion and demonstration of the highest optical-to-optical efficiency of any up-conversion laser reported to date. A US Patent was awarded for this invention in 1998.

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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....

  20. 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.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    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...

  2. 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.

  3. Fabrication and Characterization of Photonic Bandgap Components

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn

    2006-01-01

    Denne ph.d. afhandling beskæftiger sig med modelleringen, fabrikationen og karakteriseringen af fotoniske båndgabs komponenter, som er realiseret i et silicium-på-isolator materiale. Metoderne "plane-wave expansion theory" og "finite-difference time-domain modelling" er blevet anvendt til at mode...

  4. 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...

  5. 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.

  6. 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...

  7. 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.

  8. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  9. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  10. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap E/sub g1/ in the presence of a second semiconductor material of a different composition and direct bandgap E/sub g2/, wherein E/sub g2/>E/sub g1/. The second semiconductor material is not substantially etched during the method, comprising subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons are not present, the photons being of an energy greater than E/sub g1/ but less than E/sub g2/, whereby the first semiconductor material is photochemically etched and the second material is substantially not etched.

  11. Lessons learned: from dye-sensitized solar cells to all-solid-state hybrid devices.

    Science.gov (United States)

    Docampo, Pablo; Guldin, Stefan; Leijtens, Tomas; Noel, Nakita K; Steiner, Ullrich; Snaith, Henry J

    2014-06-25

    The field of solution-processed photovoltaic cells is currently in its second spring. The dye-sensitized solar cell is a widely studied and longstanding candidate for future energy generation. Recently, inorganic absorber-based devices have reached new record efficiencies, with the benefits of all-solid-state devices. In this rapidly changing environment, this review sheds light on recent developments in all-solid-state solar cells in terms of electrode architecture, alternative sensitizers, and hole-transporting materials. These concepts are of general applicability to many next-generation device platforms.

  12. Freestanding mesoporous VN/CNT hybrid electrodes for flexible all-solid-state supercapacitors.

    Science.gov (United States)

    Xiao, Xu; Peng, Xiang; Jin, Huanyu; Li, Tianqi; Zhang, Chengcheng; Gao, Biao; Hu, Bin; Huo, Kaifu; Zhou, Jun

    2013-09-25

    High-performance all-solid-state supercapacitors (SCs) are fabricated based on thin, lightweight, and flexible freestanding MVNN/CNT hybrid electrodes. The device shows a high volume capacitance of 7.9 F/cm(3) , volume energy and power density of 0.54 mWh/cm(3) and 0.4 W/cm(3) at a current density of 0.025 A/cm(3) . By being highly flexible, environmentally friendly, and easily connectable in series and parallel, the all-solid-state SCs promise potential applications in portable/wearable electronics.

  13. 五能级87Rb原子系统中相干诱导的可调谐三光子带隙%Tunable Triple Photonic Band-Gaps Based on Coherent Induction in a Five-Level 87Rb Atomic System

    Institute of Scientific and Technical Information of China (English)

    巴诺; 吴向尧; 刘晓静; 张斯淇; 王婧; 高海欣

    2012-01-01

    研究了一个由两个同向驻波场和一个微波场相干驱动的五能级87Rb原子系统,并在探测场共振频率处实现了可调谐三光子带隙.利用激光场与多能级原子系综相互作用的密度矩阵方程,结合光脉冲在具有空间周期性介质中的相干传输矩阵理论,推导出了描述相干原子系统稳态条件下的反射谱和透射谱.由数值模拟发现,通过改变驱动场的失谐和拉比频率可以动力学地调控光子带隙的位置和宽度,而且这种相干诱导三光子带隙能够同时操控三个不同中心频率光脉冲的传播.%A five-level 8?Rb atomic system which is coherently driven by two standing-wave fields and a microwave field is investigated, and tunable triple photonic band-gaps at different resonance frequencies are obtained. The density-matrix equations are used to describe the interaction between fields and multi-level atoms, and the transfer-matrix method is used to describe the propagation of light in periodic media. The reflection spectra and transmission spectra of the coherent atomic system are deduced in the steady condition. The numerical simulation show that the positions and widths of the photonic band-gaps can be controlled by the detuning of the coherent fields and the Rabi frequency of the microwave field, and the type of triple photonic band-gaps can be applied to simultaneously manipulate the propagation of light pulses with three different central frequencies.

  14. 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...

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. High power all-solid-state quasi-continuous-wave tunable Ti: sapphire laser system

    Institute of Scientific and Technical Information of China (English)

    Lei Zou; Xin Ding; Yue Zou; Hongmei Ma; Wuqi Wen; Peng Wang; Jianquan Yao

    2005-01-01

    This paper reports a high power, all-solid-state, quasi-continuous-wave tunable Ti:sapphire laser system pumped by laser diode (LD) pumped frequency-doubled Nd:YAG laser. The maximum tuned output power of 4.2 W (797 nm) and tuned average power of 3.7 W were achieved when fixing the Ti:sapphire broadband output power at 5.0 W and applying 750-850 nm broadband coated mirror.

  1. 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)

  2. 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.

  3. 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...

  4. An all-solid-state lithium ion battery electrolyte membrane fabricated by hot-pressing method

    Science.gov (United States)

    Han, Pengfei; Zhu, Yuewu; Liu, Jin

    2015-06-01

    A cross-linked polymer electrolyte membrane (SPE) was fabricated by a solvent-free hot-pressing method for all-solid-state lithium ion battery. The ionic conductivity of the electrolyte is 1.34 × 10-3 S cm-1 and the decomposition potential is 4.87 V at the ethylene oxide (EO):LiN(SO2CF3)2 (LiTFSI) molar ratio of 20:1 and 120 °C. TG-DSC results show that the SPE is thermally stable up to 230 °C in argon atmosphere. The assembled LiFePO4/SPE/Li all-solid-state battery can stably work in the temperature range of 80-140 °C. At 120 °C, the initial discharge capacity of the battery is 156.7 mAh g-1 at 1C which is close to the theoretical capacity of the cathode material, showing that the solvent-free filming method is low-cost and environment-friendly for solid polymer electrolyte and all-solid-state lithium ion battery.

  5. 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.

  6. All-solid-state lithium organic battery with composite polymer electrolyte and pillar[5]quinone cathode.

    Science.gov (United States)

    Zhu, Zhiqiang; Hong, Meiling; Guo, Dongsheng; Shi, Jifu; Tao, Zhanliang; Chen, Jun

    2014-11-26

    The cathode capacity of common lithium ion batteries (LIBs) using inorganic electrodes and liquid electrolytes must be further improved. Alternatively, all-solid-state lithium batteries comprising the electrode of organic compounds can offer much higher capacity. Herein, we successfully fabricated an all-solid-state lithium battery based on organic pillar[5]quinone (C35H20O10) cathode and composite polymer electrolyte (CPE). The poly(methacrylate) (PMA)/poly(ethylene glycol) (PEG)-LiClO4-3 wt % SiO2 CPE has an optimum ionic conductivity of 0.26 mS cm(-1) at room temperature. Furthermore, pillar[5]quinine cathode in all-solid-state battery rendered an average operation voltage of ∼2.6 V and a high initial capacity of 418 mAh g(-1) with a stable cyclability (94.7% capacity retention after 50 cycles at 0.2C rate) through the reversible redox reactions of enolate/quinonid carbonyl groups, showing favorable prospect for the device application with high capacity.

  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. Analysis of liquid crystal properties for photonic crystal fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei;

    2009-01-01

    We analyze the bandgap structure of Liquid Crystal infiltrated Photonic Crystal Fibers depending on the parameters of the Liquid Crystals by means of finite element simulations. For a biased Liquid Crystal Photonic Crystal Fiber, we show how the tunability of the bandgap position depends on the L...

  10. 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.

  11. Investigation of reflective electrochromic all-solid-state devices by Nuclear Reaction Analysis

    Science.gov (United States)

    Bange, Klaus; Ottermann, Clemens R.; Wagner, Wolfgang; Rauch, Friedrich

    1990-08-01

    Electrochromic all-solid-state devices (ASSD) produced by reactive evaporation have been investigated by iaeans of reflectance measurements in the VIS/NIR range and cyclovoltammetry. Hydrogen depth proil were then by a NRA-technique employing the resonant reaction H( N, ar) C. Two different types of designs have been characterized. The electrochromic behaviour of ASSD's can not be described by models based on H transport for devices containing only W03 layers as active materials. Using NiOXH films as electrochromic substances, the injected/ejected charge corelates with changes in the H content.

  12. All-solid-state ultraviolet laser based on frequency doubling in an external ring cavity

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An all-solid-state ultraviolet laser based on frequency doubling in an external ring cavity with low input pump power is reported. Both second harmonic generation (SHG) and fourth harmonic generation (FHG) occurred in an external threemirrors ring cavity. The need for impedance matching of this cavity to the input radiation was eliminated and the cavity adaptation was simplified, because the mirrors were not highly reflecting at 1064 nm and the cavity resonates only at 532 nm. Experiment results demonstrate that the conversion efficiency of this external cavity is higher than that of the singlepass condition.

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

    OpenAIRE

    TIRUWORK MEQUANINT; GHIRMA MOGES; MERID TESSMA; SOLOMON MEHRETU

    2012-01-01

    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 iodize...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 'All-solid-state' electrochemistry of a protein-confined polymer electrolyte film.

    Science.gov (United States)

    Parthasarathy, Meera; Pillai, Vijayamohanan K; Mulla, Imtiaz S; Shabab, Mohammed; Khan, M I

    2007-12-07

    Interfacial redox behavior of a heme protein (hemoglobin) confined in a solid polymer electrolyte membrane, Nafion (a perfluoro sulfonic acid ionomer) is investigated using a unique 'all-solid-state' electrochemical methodology. The supple phase-separated structure of the polymer electrolyte membrane, with hydrophilic pools containing solvated protons and water molecules, is found to preserve the incorporated protein in its active form even in the solid-state, using UV-visible, Fluorescence (of Tryptophan and Tyrosine residues) and DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy. More specifically, solid-state cyclic voltammetry and electrochemical impedance of the protein-incorporated polymer films reveal that the Fe2+-form of the entrapped protein is found to bind molecular oxygen more strongly than the native protein. In the 'all-solid-state' methodology, as there is no need to dip the protein-modified electrode in a liquid electrolyte (like the conventional electrochemical methods), it offers an easier means to study a number of proteins in a variety of polymer matrices (even biomimetic assemblies). In addition, the results of the present investigation could find interesting application in a variety of research disciplines, in addition to its fundamental scientific interest, including protein biotechnology, pharmaceutical and biomimetic chemistry.

  20. Fe3O4@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes.

    Science.gov (United States)

    Fan, Huailin; Niu, Ruiting; Duan, Jiaqi; Liu, Wei; Shen, Wenzhong

    2016-08-03

    Fe3O4@carbon nanosheet composites were synthesized using ammonium ferric citrate as the Fe3O4/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe3O4 composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe3O4 nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, and the utmost utilization of Fe3O4 and resulted in excellent specific capacitance, outstanding rate capability and cycling life as all-solid-state supercapacitor electrodes.

  1. 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.

  2. 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.

  3. 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%.

  4. All-solid-state micro-supercapacitors based on inkjet printed graphene electrodes

    Science.gov (United States)

    Li, Jiantong; Mishukova, Viktoriia; Östling, Mikael

    2016-09-01

    The all-solid-state graphene-based in-plane micro-supercapacitors are fabricated simply through reliable inkjet printing of pristine graphene in interdigitated structure on silicon wafers to serve as both electrodes and current collectors, and a following drop casting of polymer electrolytes (polyvinyl alcohol/H3PO4). Benefiting from the printing processing, an attractive porous electrode microstructure with a large number of vertically orientated graphene flakes is observed. The devices exhibit commendable areal capacitance over 0.1 mF/cm2 and a long cycle life of over 1000 times. The simple and scalable fabrication technique for efficient micro-supercapacitors is promising for on-chip energy storage applications in emerging electronics.

  5. 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...

  6. Nonenzymatic all-solid-state coated wire electrode for acetylcholine determination in vitro.

    Science.gov (United States)

    He, Cheng; Wang, Zhan; Wang, You; Hu, Ruifen; Li, Guang

    2016-11-15

    A nonenzymatic all-solid-state coated wire acetylcholine electrode was investigated. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT/PSS) as conducting polymer was coated on one end of a gold wire (0.5mm in diameter). The acetylcholine selective membrane containing heptakis(2,3,6-tri-Ο-methyl)-β-cyclodextrin as an ionophore covered the conducting polymer layer. The electrode could work stably in a pH range of 6.5-8.5 and a temperature range of 15-40°C. It covered an acetylcholine concentration range of 10(-5)-10(-1)M with a slope of 54.04±1.70mV/decade, while detection limit was 5.69±1.06µM. The selectivity, dynamic response, reproducibility and stability were evaluated. The electrode could work properly in the rat brain homogenate to detect different concentrations of acetylcholine.

  7. 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.

  8. 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.

  9. Laminated all-solid state NiO/WO3 complementary electrochromic device

    Institute of Scientific and Technical Information of China (English)

    胡行方; 陈晓峰; 李智勇; 高濂; 严东生

    1997-01-01

    Based on the previous studies on the rf reactive sputtered nickel oxide film with nanostructure and its electrochromism, i. e. electrochromic effect of the films is attributed to the reversible change of the non-stoichiometry in the nanocrystaltine gram boundaries and interfaces due to the injection and ejection of Li+ ions, a prototype of all-solid-state NiO/WO3 complementary electrochromic device using LixTaOy thin film as inorganic electrolyte was designed and prepared. The results indicate that the solar reflectance of the device could be modulated from 0. 15 in colored state to 0.60 in bleached state with excellent cyclic reversibility, durability and high response speed (less than 0.3 s from colored state to bleached state).

  10. 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.

  11. 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.

  12. 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...

  13. High Power Widely Tunable Narrow Linewidth All-Solid-State Pulsed Titanium-Doped Sapphire Laser

    Institute of Scientific and Technical Information of China (English)

    DING Xin; LI Xue; SHENG Quan; SHI Chun-Peng; YIN Su-Jia; LI Bin; YU Xuan-Yi; WEN Wu-Qi; YAO Jian-Quan

    2011-01-01

    We report a widely tunable, narrow linewidth, pulsed Ti:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser. By using four dense Bint glass prisms as intra-cavity dispersive elements, the output wavelength can be continuously tuned over 675-970 nm and the spectral linewidth is shortened to 0.5nm. The maximum output power of 6.65 W at 780 nm is obtained under 23.4 Wpump power with repetition rate of 5.5 kHz; corresponding to an conversion efficiency of 28.4%. Due to the gain-switching characteristics of the Ti:sapphire laser, the output pulse duration is as short as 17.6ns.%@@ We report a widely tunable,narrow linewidth,pulsed Th:sapphire laser pumped by an all-solid-state Q-switched intra-cavity frequency-doubled Nd:YAG laser.By using four dense flint glass prisms as intra-cavity dispersive elements,the output wavelength can be continuously tuned over 675-970nm and the spectral linewidth is shortened to 0.5 nm.The maximum output power of 6.65 W at 780 run is obtained under 23.4 W pump power with repetition rate of 5.5 kHz,corresponding to an conversion efficiency of 28.4%.Due to the gain-switching characteristics of the Ti:sapphire laser,the output pulse duration is as short as 17.6ns.

  14. Polymer-nanocomposite brush-like architectures as an all-solid electrolyte matrix.

    Science.gov (United States)

    Gowneni, Soujanya; Ramanjaneyulu, Kota; Basak, Pratyay

    2014-11-25

    Herein, we report on polymer-nanocomposites with brush-like architectures and evaluate their feasibility as an all-solid electrolyte matrix supporting Li(+)-ion conduction. Showcased as a first example in the domain of electrolyte research, the study probes several key factors, such as (i) core morphology, (ii) surface modifiers/functionality, (iii) grafting length, and (iv) density of the brushes, and determines their role on the overall electrochemical properties of these nanostructured organic-inorganic hybrids. Nanostructured titania was synthesized via wet-chemical approaches using either controlled hydrolysis or hydrothermal methods. Exercising suitable control on reaction parameters led to well-defined morphologies/phases, such as nanoparticles, nanospindles, nanourchins, nanorods or nanotubes, in either anatase, rutile or mixed forms. Covalent anchoring on titania nanostructures was achieved using dopamine, gallic acid and glycerol as small organic moieties. A one-pot process of priming the available surface functional groups postmodification with isocyanate chemistry was followed by grafting polyethylene glycol monomethyl ethers of desired chain lengths. Finally, complexation with lithium salt yielded electrolyte compositions where the ethylene oxide (EO) fractions aid in ion-solvation with ease. The synthesized materials were characterized in detail employing XRD, TEM, DRS-UV, FTIR, micro-Raman, TG-DTA and DSC at each stage to confirm the products and ascertain the physicochemical properties. Comprehensive evaluation using temperature-step electrochemical impedance spectroscopy (EIS) of these brush-like nanocomposites provided crucial leads toward establishing a plausible physical model for the system and understanding the mechanism of ion transport in these all-solid matrices. The preliminary results on ionic conductivity (σ) obtained for some of the compositions are estimated to be within the range of ∼10(-4) to 10(-5) S cm(-1) in the temperature

  15. 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.

  16. Analysis of bandgap characteristics of two-dimensional periodic structures by using the source-model technique.

    Science.gov (United States)

    Ludwig, Alon; Leviatan, Yehuda

    2003-08-01

    We introduce a solution based on the source-model technique for periodic structures for the problem of electromagnetic scattering by a two-dimensional photonic bandgap crystal slab illuminated by a transverse-magnetic plane wave. The proposed technique takes advantage of the periodicity of the slab by solving the problem within the unit cell of the periodic structure. The results imply the existence of a frequency bandgap and provide a valuable insight into the relationship between the dimensions of a finite periodic structure and its frequency bandgap characteristics. A comparison shows a discrepancy between the frequency bandgap obtained for a very thick slab and the bandgap obtained by solving the corresponding two-dimensionally infinite periodic structure. The final part of the paper is devoted to explaining in detail this apparent discrepancy.

  17. 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.

  18. Developments of high-voltage all-solid-state thin-film lithium ion batteries

    Science.gov (United States)

    Schwenzel, J.; Thangadurai, V.; Weppner, W.

    Powders of Li 2MMn 3O 8 (M = Fe, Co) were prepared by glycine nitrate combustion from the corresponding metal nitrates. The reaction products were pressed into pellets with the addition of 20 wt.% excess LiNO 3, which were used as targets for e-beam evaporation. A high-voltage all-solid-state thin-film lithium ion battery was demonstrated by the sequential deposition of spinel structured Li 2MMn 3O 8 (M = Co, Fe) as positive electrode by e-beam evaporation, LiPON as electrolyte, and metallic Al as negative electrode by sputtering in N 2 and Ar gas mixtures with specific power and gas flow rates. A lithium ion conductivity of ∼10 -6 S cm -1 was observed for the optimized thin-film LiPON electrolyte prepared under the condition of a chamber pressure of 2.6 × 10 -2 mbar and a power of 60-100 W. The chemical diffusion coefficient (D ˜) was found to be in the range 10 -13 to 10 -12 cm 2 s -1 for any composition x of Li 2- xMMn 3O 8 (M = Fe, Co) in the range from 0.1 to 1.6 by employing the galvanostatic intermittent titration technique (GITT). AC impedance studies revealed a charge transfer resistance of 260-290 Ω, a double layer capacity of ∼45-70 μF for an electrode area of 6.7 cm 2.

  19. All-solid-state carbonate-selective electrode based on screen-printed carbon paste electrode

    Science.gov (United States)

    Li, Guang; Lyu, Xiaofeng; Wang, Zhan; Rong, Yuanzhen; Hu, Ruifen; Luo, Zhiyuan; Wang, You

    2017-02-01

    A novel disposable all-solid-state carbonate-selective electrode based on a screen-printed carbon paste electrode using poly(3-octylthiophene-2,5-diyl) (POT) as an ion-to-electron transducer has been developed. The POT was dropped onto the reaction area of the carbon paste electrode covered by the poly(vinyl chloride) (PVC) membrane, which contains N,N-Dioctyl-3α,12α-bis(4-trifluoroacetylbenzoyloxy)-5β-cholan-24-amide as a carbonate ionophore. The electrode showed a near-Nernstian slope of  -27.5 mV/decade with a detection limit of 3.6 * 10-5 mol l-1. Generally, the detection time was 30 s. Because these electrodes are fast, convenient and low in cost, they have the potential to be mass produced and used in on-site testing as disposable sensors. Furthermore, the repeatability, reproducibility and stability have been studied to evaluate the properties of the electrodes. Measurement of the carbonate was also conducted in a human blood solution and achieved good performance.

  20. 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.

  1. 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

    2016-05-04

    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.

  2. All solid-state high power microwave source with high repetition frequency.

    Science.gov (United States)

    Bragg, J-W B; Sullivan, W W; Mauch, D; Neuber, A A; Dickens, J C

    2013-05-01

    An all solid-state, megawatt-class high power microwave system featuring a silicon carbide (SiC) photoconductive semiconductor switch (PCSS) and a ferrimagnetic-based, coaxial nonlinear transmission line (NLTL) is presented. A 1.62 cm(2), 50 kV 4H-SiC PCSS is hard-switched to produce electrical pulses with 7 ns full width-half max (FWHM) pulse widths at 2 ns risetimes in single shot and burst-mode operation. The PCSS resistance drops to sub-ohm when illuminated with approximately 3 mJ of laser energy at 355 nm (tripled Nd:YAG) in a single pulse. Utilizing a fiber optic based optical delivery system, a laser pulse train of four 7 ns (FWHM) signals was generated at 65 MHz repetition frequency. The resulting electrical pulse train from the PCSS closely follows the optical input and is utilized to feed the NLTL generating microwave pulses with a base microwave-frequency of about 2.1 GHz at 65 MHz pulse repetition frequency (prf). Under typical experimental conditions, the NLTL produces sharpened output risetimes of 120 ps and microwave oscillations at 2-4 GHz that are generated due to damped gyromagnetic precession of the ferrimagnetic material's axially pre-biased magnetic moments. The complete system is discussed in detail with its output matched into 50 Ω, and results covering MHz-prf in burst-mode operation as well as frequency agility in single shot operation are discussed.

  3. All-solid-state repetitive semiconductor opening switch-based short pulse generator.

    Science.gov (United States)

    Ding, Zhenjie; Hao, Qingsong; Hu, Long; Su, Jiancang; Liu, Guozhi

    2009-09-01

    The operating characteristics of a semiconductor opening switch (SOS) are determined by its pumping circuit parameters. SOS is still able to cut off the current when pumping current duration falls to the order of tens of nanoseconds and a short pulse forms simultaneously in the output load. An all-solid-state repetitive SOS-based short pulse generator (SPG100) with a three-level magnetic pulse compression unit was successfully constructed. The generator adopts magnetic pulse compression unit with metallic glass and ferrite cores, which compresses a 600 V, 10 mus primary pulse into short pulse with forward pumping current of 825 A, 60 ns and reverse pumping current of 1.3 kA, 30 ns. The current is sent to SOS in which the reverse pumping current is interrupted. The generator is capable of providing a pulse with the voltage of 120 kV and duration of 5-6 ns while output load being 125 Omega. The highest repetition rate is up to 1 kHz.

  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. 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.

  6. From optical MEMS to photonic crystal

    Science.gov (United States)

    Lee, Sukhan; Kim, Jideog; Lee, Hong-Seok; Moon, Il-Kwon; Won, JongHwa; Ku, Janam; Choi, Hyung; Shin, Hyungjae

    2002-10-01

    This paper presents the emergence of photonic crystals as significant optomechatronics components, following optical MEMS. It is predicted that, in the coming years, optical MEMS and photonic crystals may go through dynamic interactions leading to synergy as well as competition. First, we present the Structured Defect Photonic Crystal (SDPCTM) devised by the authors for providing the freedom of designing photonic bandgap structures, such that the application of photonic crystals be greatly extended. Then, we present the applications of optical MEMS and photonic crystals to displays and telecommunications. It is shown that many of the applications that optical MEMS can contribute to telecommunications and displays may be implemented by photonic crystals.

  7. Distributed optical fibre devices based on liquid crystal infiltrated photonic crystal fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Broeng, Jes; Hermann, D.S.

    2004-01-01

    We describe a new class of hybrid photonic crystal fibers, which are liquid crystal infiltrated fibers. Using these fibers, we demonstrate 'distributed' tunable filter and switching functionalities operating by the photonic bandgap effect....

  8. Optical reflectance and omnidirectional bandgaps in Fibonacci quasicrystals type 1-D multilayer structures containing exponentially graded material

    Science.gov (United States)

    Singh, Bipin K.; Thapa, Khem B.; Pandey, Praveen C.

    2013-06-01

    A theoretical study of optical reflectance and reflection bands of 1-D photonic quasi-crystals (Fibonacci type arrangement) composed of exponentially graded material is presented. The proposed structures consist of two different layers, one of them is of constant refractive index (L) and the other one is of exponentially graded refractive index (S) dielectric materials. Four different generations (2nd, 3rd, 4th and 5th) of the Fibonacci sequence for 10 periods in one dimension (1-D) are considered and compared in view of their optical reflectance and bandgaps for both TE and TM polarisations. Also, we proposed some heterostructures made by the combination of different Fibonacci generations and their periods to obtain suitable omnidirectional reflection band. We used the transfer matrix method (TMM) to obtain the reflectance, bandgaps and omnidirectional reflectional bandgaps (ODR) of such structures in near infrared spectrum (800-2200 nm) at different angles of incidence. We show that ODR exists in these types of structures. The number of ODRs and total bandgap depend on the Fibonacci generations. Extraordinary ODR bandgaps are obtained in the case of heterostructures formed by the combination of different generations of the Fibonacci sequence. The ODR for these structures is similar to the ODR of photonic crystals containing left-handed materials. This work would be useful to study the Fibonacci type photonic crystals having graded index materials and also it will open new window to design several photonic crystal devices like sensors, reflectors, etc. in the infrared region.

  9. 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.

  10. Nonlinear spatial mode imaging of hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

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

    2013-01-01

    Degenerate spontaneous four wave mixing is studied for the rst time in a large mode area hybrid photonic crystal ber, where light con nement is achieved by combined index- and bandgap guiding. Four wave mixing products are generated on the edges of the bandgaps, which is veri ed by numerical...

  11. Design of robust and efficient photonic switches using topology optimization

    DEFF Research Database (Denmark)

    Elesin, Yuriy; Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard

    2012-01-01

    are insensitive with respect to variations of signal parameters, such as signal amplitudes and phase shifts. The obtained robust designs of a 1D photonic switch can substantially outperform simple bandgap designs, known from the literature, where switching takes place due to the bandgap shift produced by a strong...

  12. 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.

  13. 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...

  14. 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.

  15. Graphene Photonics and Optoelectronics

    OpenAIRE

    Bonaccorso, F.; Z. Sun; 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, ...

  16. Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

    Science.gov (United States)

    Sakamoto, Y.; Ishii, Y.; Kawasaki, S.

    2016-07-01

    Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

  17. All-solid-state reduced graphene oxide supercapacitor with large volumetric capacitance and ultralong stability prepared by electrophoretic deposition method.

    Science.gov (United States)

    Wang, Mei; Duong, Le Dai; Mai, Nguyen Thi; Kim, Sanghoon; Kim, Youngjun; Seo, Heewon; Kim, Ye Chan; Jang, Woojin; Lee, Youngkwan; Suhr, Jonghwan; Nam, Jae-Do

    2015-01-21

    Portable energy storage devices have gained special attention due to the growing demand for portable electronics. Herein, an all-solid-state supercapacitor is successfully fabricated based on a poly(vinyl alcohol)-H3PO4 (PVA-H3PO4) polymer electrolyte and a reduced graphene oxide (RGO) membrane electrode prepared by electrophoretic deposition (EPD). The RGO electrode fabricated by EPD contains an in-plane layer-by-layer alignment and a moderate porosity that accommodate the electrolyte ions. The all-solid-state RGO supercapacitor is thoroughly tested to give high specific volumetric capacitance (108 F cm(-3)) and excellent energy and power densities (7.5 Wh cm(-3) and 2.9 W cm(-3), respectively). In addition, the all-solid-state RGO supercapacitor exhibits an ultralong lifetime for as long as 180 days (335 000 cycles), which is an ultrahigh cycling capability for a solid-state supercapacitor. The RGO is also tested for being used as a transparent supercapacitor electrode demonstrating its possible use in various transparent optoelectronic devices. Due to the facile scale-up capability of the EPD process and RGO dispersion, the developed all-solid-state supercapacitor is highly applicable to large-area portable energy storage devices.

  18. 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

  19. Anode properties of magnesium hydride catalyzed with niobium oxide for an all solid-state lithium-ion battery.

    Science.gov (United States)

    Ikeda, Suguru; Ichikawa, Takayuki; Kawahito, Koji; Hirabayashi, Kazuhiro; Miyaoka, Hiroki; Kojima, Yoshitsugu

    2013-08-18

    The anode properties of pristine MgH2 and MgH2 catalyzed with Nb2O5 have been investigated for an all solid-state lithium-ion battery. The catalytic effect stabilizes the plateau voltage as a result of kinetic improvement of the hydrogen transfer from the Mg phase to the Li phase.

  20. 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)

  1. 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...

  2. Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites.

    Science.gov (United States)

    Dar, M Ibrahim; Jacopin, Gwénolé; Meloni, Simone; Mattoni, Alessandro; Arora, Neha; Boziki, Ariadni; Zakeeruddin, Shaik Mohammed; Rothlisberger, Ursula; Grätzel, Michael

    2016-10-01

    Emission characteristics of metal halide perovskites play a key role in the current widespread investigations into their potential uses in optoelectronics and photonics. However, a fundamental understanding of the molecular origin of the unusual blueshift of the bandgap and dual emission in perovskites is still lacking. In this direction, we investigated the extraordinary photoluminescence behavior of three representatives of this important class of photonic materials, that is, CH3NH3PbI3, CH3NH3PbBr3, and CH(NH2)2PbBr3, which emerged from our thorough studies of the effects of temperature on their bandgap and emission decay dynamics using time-integrated and time-resolved photoluminescence spectroscopy. The low-temperature (perovskite composition, the bandgap exhibits an unusual blueshift by raising the temperature from 15 to 300 K. Density functional theory and classical molecular dynamics simulations allow for assigning the additional photoluminescence peak to the presence of molecularly disordered orthorhombic domains and also rationalize that the unusual blueshift of the bandgap with increasing temperature is due to the stabilization of the valence band maximum. Our findings provide new insights into the salient emission properties of perovskite materials, which define their performance in solar cells and light-emitting devices.

  3. 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....

  4. 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

  5. Photonic crystal alloys: a new twist in controlling photonic band structure properties.

    Science.gov (United States)

    Kim, Hee Jin; Kim, Dong-Uk; Roh, Young-Geun; Yu, Jaejun; Jeon, Heonsu; Park, Q-Han

    2008-04-28

    We identified new photonic structures and phenomenon that are analogous to alloy crystals and the associated electronic bandgap engineering. From a set of diamond-lattice microwave photonic crystals of randomly mixed silica and alumina spheres but with a well defined mixing composition, we observed that both bandedges of the L-point bandgap monotonically shifted with very little bowing as the composition was varied. The observed results were in excellent agreement with the virtual crystal approximation theory originally developed for electronic properties of alloy crystals. This result signifies the similarity and correspondence between photonics and electronics.

  6. Wide Bandgap Semiconductor Nanowires for Electronic, Photonic and Sensing Devices

    Science.gov (United States)

    2012-01-05

    exciton emission at 3.24 eV. Also, the ZnO nanorods can be integrated with AlGaN/ GaN HEMT sensors by incorporating the nano-rods on the HEMT gate sensing...area, the total sensing area increases significantly. The conventional AlGaN/ GaN HEMT detects the ambient changes through the “gate sensing area...glucose interaction to the AlGaN/ GaN HEMT . With such low detection limit, it is possible to dilute ɘ.1 micro-liter of EBC in 100-200 micro-liter

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

    DEFF Research Database (Denmark)

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

    2005-01-01

    -size thickness variations result in the pronounced band gap effect, and obtain very good agreement between measured and simulated (transmission and reflection) spectra. This effect is exploited to realize a compact wavelength add-drop filter with the bandwidth of -20 nm centered at 1550 nm. The possibilities...

  8. 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...

  9. Optical devices based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard

    2005-01-01

    of LCs combined with the unique waveguiding features of PBG fibers gives the LC filled PCFs unique tunable properties. PBG guidance has been demonstrated for different mesophases of LCs and various functional compact fibers has been demonstrated, which utilitzes the high thermo-optical and electro-optical...... effects of LCs. Thermally controlled spectral filters and broadband switching functionalities, electrically controlled switches, polarizers and polarization rotators and an all-optical modulator has been demonstrated. The waveguiding mechanism of anistotropic PBGs fibers has been analyzed and spectral...

  10. 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.

  11. DNA-Based Photonic Bandgap Structures and Devices

    Science.gov (United States)

    2009-11-29

    Genes to Machines: DNA Nanomechanical Devices, Trends in Biochemical Sciences 30, 119-125 (2005). 4. N.C. Seeman. Structural DNA Nanotechnology: An... kpc ≥ ω , k becomes purely real.. If the dispersion relation just given is written as =++ 22)( kpkak 1ε 2)( c ω , it resembles that for modes in a...waveguide. By analogy, the frequency region for which 1ε 22)( kpc < ω will be referred to as cutoff. IV. APPLICATIONS The presence of molecules

  12. Gap solitons in inhomogeneous high-index photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2011-01-01

    will be driven towards the zerovelocity state [2,3]. An important question in connection with slow-light propagation is the influence of waveguide imperfections, which typically leads to a strong scattering of the slow light as the group velocity tends to zero. Theoretical investigations of this subject have so...

  13. Photosensitive, all-glass AgPO3/silicaphotonic bandgap fiber.

    Science.gov (United States)

    Konidakis, Ioannis; Zito, Gianluigi; Pissadakis, Stavros

    2012-07-01

    Photonic bandgap (PBG) guidance is observed in a solid core photonic crystal fiber (PCF) consisting of silver metaphosphate (AgPO(3)) glass embedded into a silica cladding, realized by vacuum-assisted infiltration of the molten glass into the hollow channels of a commercial silica PCF. Morphologic analysis of the cladding microstructure by optical and scanning electron microscopy reveals the formation of highly homogeneous glass strands along the PCF length. The characteristic transmission spectrum of the fiber shows PBG guidance in the range between 350 and 1650 nm. The exposure of the cladding glass matrix, using 355 nm, 150 ps laser irradiation, allows photo-induced enhancement of the transmission-to-stop-band extinction ratio by ∼60 dB/cm and bandwidth tuning. Numerical calculations of the transmission pattern of the fabricated AgPO(3)/silica bandgap fiber are in good agreement with experiments.

  14. Mid-Infrared Optical Parametric Oscillator Based on All-Solid-State-Pumped Periodically Poled LiNbO

    Institute of Scientific and Technical Information of China (English)

    林学春; 毕勇; 姚爱云; 孔宇鹏; 张瑛; 孙志培; 李瑞宁; 崔大复; 许祖彦; 李健

    2003-01-01

    We report the tunable mid-infrared generation with a periodically poled LiNbO3 (PPLN). Using an all-solid-statepumped Nd: YVO4 laser as the pump source and a PPLN nonlinear crystal with grating periods of 28.2-30.8 μm,we have achieved wavelength conversion in the 2.90-4.05 μm spectral range by period tuning. The use of confocal cavity design has brought a compact, all-solid-state configuration with an average output powers of idler up to ~ 200 mW. The maximum power of 277mW was obtained at the wavelength of 3.35μm.

  15. All-Solid-State Lithium-Ion Batteries with Grafted Ceramic Nanoparticles Dispersed in Solid Polymer Electrolytes.

    Science.gov (United States)

    Lago, Nerea; Garcia-Calvo, Oihane; Lopez del Amo, Juan Miguel; Rojo, Teofilo; Armand, Michel

    2015-09-21

    Lithium-based rechargeable batteries offer superior specific energy and power, and have enabled exponential growth in industries focused on small electronic devices. However, further increases in energy density, for example for electric transportation, face the challenge of harnessing the lithium metal as negative electrode instead of limited-capacity graphite and its heavy copper current collector. All-solid-state batteries utilize solid polymer electrolytes (SPEs) to overcome the safety issues of liquid electrolytes. We demonstrate an all-solid-state lithium-ion battery by using plasticized poly(ethylene oxide)-based SPEs comprising anions grafted or co-grafted onto ceramic nanoparticles. This new approach using grafted ceramic nanoparticles enables the development of a new generation of nanohybrid polymer electrolytes with high ionic conductivity as well as high electrochemical and mechanical stability, enabling Li-ion batteries with long cycle life.

  16. 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.

  17. 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.

  18. Design of a Polymer-Based Hollow-Core Bandgap Fiber for Low-Loss Terahertz Transmission

    DEFF Research Database (Denmark)

    Barh, Ajanta; Varshney, Ravi K.; Pal, Bishnu P.;

    2016-01-01

    wavelength-scale circular air holes in a hexagonal pattern, embedded in a uniform Teflon matrix. The THz guidance in this fiber is achieved by exploiting the photonic bandgap (PBG) effect. In our low index contrast Teflon-air (1.44:1) hexagonal periodic lattice, the PBG appears only for a certain range...

  19. Optically fed microwave true-time delay based on a compact liquid-crystal hotonic-bandgap-fiber device

    DEFF Research Database (Denmark)

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

    2009-01-01

    An electrically tunable liquid-crystal, photonic-bandgap-fiber-device-based, optically fed microwave true-time delay is demonstrated with the response time in the millisecond range. A maximum electrically controlled phase shift of around 70° at 15GHz and an averaged 12.9ps true time delay over...

  20. Photonic crystal fibres - a variety of applications

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Riishede, Jesper

    2002-01-01

    Summary form only given. In 1987, it was suggested that the electronic bandgaps in semiconductors could have an optical analogy-the so-called photonic bandgaps (PBGs), which could be found in periodic dielectric structures. This suggestion initiated research activities that the past few years have...... lead to a new class of optical fibers, in which the cladding structure consists of a periodic system of air holes in a matrix of dielectric material-typically silica. These fibers have been given several names ranging from holey fibers, microstructured fibers, photonic crystal fibers, to photonic...... bandgap fibers. These fibers have today reached a level of maturity where they may be used as building blocks for a variety of new applications. Today's research is focusing increasingly on applications of the fibres, thus redirecting earlier focus on crystal fibers themselves and their unique guiding...

  1. 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.

  2. 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

  3. 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.

  4. Microfabricated bulk wave acoustic bandgap device

    Science.gov (United States)

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, Carol

    2010-06-08

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  5. Direct experimental observation of giant Goos-Hänchen shifts from bandgap-enhanced total internal reflection.

    Science.gov (United States)

    Wan, Yuhang; Zheng, Zheng; Kong, Weijing; Liu, Ya; Lu, Zhiting; Bian, Yusheng

    2011-09-15

    Giant Goos-Hänchen (GH) shifts are experimentally demonstrated from a prism-coupled multilayer structure incorporating a one-dimensional photonic crystal (PC) through a bandgap-enhanced total internal reflection scheme. By combining the large phase changes near the bandgap of the PC and the low reflection loss of the total internal reflection, 2 orders of magnitude enhancement of the GH shift is realized with rather low extra optical loss, which might help to open the door toward many interesting applications for GH effects.

  6. 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.

  7. Ultrahigh energy density realized by a single-layer β-Co(OH)2 all-solid-state asymmetric supercapacitor.

    Science.gov (United States)

    Gao, Shan; Sun, Yongfu; Lei, Fengcai; Liang, Liang; Liu, Jiawei; Bi, Wentuan; Pan, Bicai; Xie, Yi

    2014-11-17

    A conceptually new all-solid-state asymmetric supercapacitor based on atomically thin sheets is presented which offers the opportunity to optimize supercapacitor properties on an atomic level. As a prototype, β-Co(OH)2 single layers with five-atoms layer thickness were synthesized through an oriented-attachment strategy. The increased density-of-states and 100 % exposed hydrogen atoms endow the β-Co(OH)2 single-layers-based electrode with a large capacitance of 2028 F g(-1) . The corresponding all-solid-state asymmetric supercapacitor achieves a high cell voltage of 1.8 V and an exceptional energy density of 98.9 Wh kg(-1) at an ultrahigh power density of 17 981 W kg(-1) . Also, this integrated nanodevice exhibits excellent cyclability with 93.2 % capacitance retention after 10 000 cycles, holding great promise for constructing high-energy storage nanodevices.

  8. The improvement of all-solid-state electrochromic devices fabricated with the reactive sputter and cathodic arc technology

    Science.gov (United States)

    Wang, Min-Chuan; Chen, Yung-Chih; Hsieh, Ming-Hao; Li, Yu-Chen; Wang, Jen-Yuan; Wu, Jin-Yu; Tsai, Wen-Fa; Jan, Der-Jun

    2016-11-01

    The all-solid-state electrochromic device (ECD) with the one substrate structure fabricated by the reactive dc magnetron sputtering (DCMS) and cathodic vacuum arc plasma (CVAP) technology has been developed for smart electrochromic (EC) glass application. The EC layer and ion conductor layer were deposited by reactive DCMS and CVAP technology, respectively. The ion conductor layer Ta2O5 deposited by the CVAP technology has provided the better porous material structure for ion transportation and showed 1.76 times ion conductivity than devices with all sputtering process. At the same time, the EC layer WO3 and NiO deposited by the reactive DCMS have also provided the high quality and uniform characteristic to overcome the surface roughness effect of the CVAP ion conductor layer in multilayer device structure. The all-solid-state ECD with the CVAP ion conductor layer has demonstrated a maximum transmittance variation (Δ T ) of 55% at 550nm and a faster-switching speed. Furthermore, the lower equipment cost and higher deposition rate could be achieved by the application of CVAP technology.

  9. All-Solid-State Stretchable Pseudocapacitors Enabled by Carbon Nanotube Film-Capped Sandwich-like Electrodes.

    Science.gov (United States)

    Gu, Taoli; Wei, Bingqing

    2016-09-28

    Stretchable pseudocapacitors have demonstrated perspective potential as the power sources for stretchable/flexible electronics. However, one of the main limitations is to increase the mass loading of pseudocapacitive materials while maintaining high electrochemical performance. Therefore, the architectural design of stable and stretchable electrodes with a high mass loading of pseudocapacitive materials becomes critical and desirable. Here we report an all-solid-state sandwich-like stretchable pseudocapacitor, which overcomes the limitation of maximum loading of active pseudocapacitive materials and exhibits excellent structural and electrochemical stabilities, giving rise to outstanding cycling stability and rate capability. The enhanced pseudocapacitive performances result from the synergistic effect in the all-solid-state and binder-free structure: (1) faster ion diffusion rates and charge transport at electrode/electrolyte interfaces and (2) improved mechanical property to mitigate the electrode degradation caused by ion insertion/extraction during charge-discharge and mechanically stretching-releasing cycles. This novel component-level design offers an effective way to improve the electrochemical performance of stretchable pseudocapacitors, and more importantly, this concept can be extended for improving the performance of other electrochemical systems such as stretchable supercapacitors, lithium-ion batteries, lithium-sulfur batteries, and solar cells, and accelerate its applications for wearable and implantable electronics.

  10. The improvement of all-solid-state electrochromic devices fabricated with the reactive sputter and cathodic arc technology

    Directory of Open Access Journals (Sweden)

    Min-Chuan Wang

    2016-11-01

    Full Text Available The all-solid-state electrochromic device (ECD with the one substrate structure fabricated by the reactive dc magnetron sputtering (DCMS and cathodic vacuum arc plasma (CVAP technology has been developed for smart electrochromic (EC glass application. The EC layer and ion conductor layer were deposited by reactive DCMS and CVAP technology, respectively. The ion conductor layer Ta2O5 deposited by the CVAP technology has provided the better porous material structure for ion transportation and showed 1.76 times ion conductivity than devices with all sputtering process. At the same time, the EC layer WO3 and NiO deposited by the reactive DCMS have also provided the high quality and uniform characteristic to overcome the surface roughness effect of the CVAP ion conductor layer in multilayer device structure. The all-solid-state ECD with the CVAP ion conductor layer has demonstrated a maximum transmittance variation (ΔT of 55% at 550nm and a faster-switching speed. Furthermore, the lower equipment cost and higher deposition rate could be achieved by the application of CVAP technology.

  11. High Performance All-Solid-State Flexible Micro-Pseudocapacitor Based on Hierarchically Nanostructured Tungsten Trioxide Composite.

    Science.gov (United States)

    Huang, Xuezhen; Liu, Hewei; Zhang, Xi; Jiang, Hongrui

    2015-12-23

    Microsupercapacitors (MSCs) are promising energy storage devices to power miniaturized portable electronics and microelectromechanical systems. With the increasing attention on all-solid-state flexible supercapacitors, new strategies for high-performance flexible MSCs are highly desired. Here, we demonstrate all-solid-state, flexible micropseudocapacitors via direct laser patterning on crack-free, flexible WO3/polyvinylidene fluoride (PVDF)/multiwalled carbon nanotubes (MWCNTs) composites containing high levels of porous hierarchically structured WO3 nanomaterials (up to 50 wt %) and limited binder (PVDF, work leads to an areal capacitance of 62.4 mF·cm(-2) and a volumetric capacitance of 10.4 F·cm(-3), exceeding that of graphene based flexible MSCs by a factor of 26 and 3, respectively. As a noncarbon based flexible MSC, hierarchically nanostructured WO3 in the narrow finger electrode is essential to such enhancement in energy density due to its pseudocapacitive property. The effects of WO3/PVDF/MWCNTs composite composition and the dimensions of interdigital structure on the performance of the flexible MSCs are investigated.

  12. Diamond Opal-Replica Photonic Crystals and Graphitic Metallic Photonic Band Gap Structures: Fabrication and Properties

    Science.gov (United States)

    Zakhidov, A. A.; Baughman, R. H.; Iqbal, Z.; Khayrullin, I. I.; Ralchenko, V. G.

    1998-03-01

    We demonstrate a new method for the formation of photonic bandgap crystals that operate at optical wavelengths. This method involves the templating of a self-assempled SiO2 lattice with diamond, graphite, or amorphous forms of carbon, followed by the removal of the original SiO2 lattice matrix by chemical means. Such carbon opal replicas are the "air type" of photonic crystal (where air replaces silica spheres) that are most favourable for photonic bandgap formation. Surprisingly, the structure of the original opal lattice having a typical cubic lattice dimension of 250 nm) is reliably replicated down to the nanometer scale using either a diamond, graphite, or amorphous carbon templated material. The optical properties of these photonic bandgap crystals are reported and compared with both theory and experimental results on other types of opal-derived lattices that we have investigated. The graphitic reverse opal is the first example of a network type metallic photonic crystal for the optical domain, for which a large photonic bandgap have been predicted.

  13. Q-switched all-solid-state lasers and application in processing of thin-film solar cell

    Science.gov (United States)

    Liu, Liangqing; Wang, Feng

    2009-08-01

    Societal pressure to renewable clean energy is increasing which is expected to be used as part of an overall strategy to address global warming and oil crisis. Photovoltaic energy conversion devices are on a rapidly accelerating growth path driven by government, of which the costs and prices lower continuously. The next generation thin-film devices are considered to be more efficiency and greatly reduced silicon consumption, resulting in dramatically lower per unit fabrication costs. A key aspect of these devices is patterning large panels to create a monolithic array of series-interconnected cells to form a low current, high voltage module. This patterning is accomplished in three critical scribing processes called P1, P2, and P3. All-solid-state Q-switched lasers are the technology of choice for these processes, due to their advantages of compact configuration, high peak-value power, high repeat rate, excellent beam quality and stability, delivering the desired combination of high throughput and narrow, clean scribes. The end pumped all-solid-state lasers could achieve 1064nm IR resources with pulse width of nanoseconds adopting acoustic-optics Q-switch, shorter than 20ns. The repeat rate is up to 100kHz and the beam quality is close to diffraction limit. Based on this, 532nm green lasers, 355nm UV lasers and 266nm DUV lasers could be carried out through nonlinear frequency conversion. Different wave length lasers are chose to process selective materials. For example, 8-15 W IR lasers are used to scribe the TCO film (P1); 1-5 W green lasers are suitable for scribing the active semiconductor layers (P2) and the back contact layers (P3). Our company, Wuhan Lingyun Photo-electronic System Co. Ltd, has developed 20W IR and 5W green end-pumped Q-switched all-solid-state lasers for thin-film solar industry. Operating in high repeat rates, the speed of processing is up to 2.0 m/s.

  14. Quantum Transport Theory for Photonic Networks

    CERN Document Server

    Lei, Chan U

    2010-01-01

    In this paper, we develop a quantum transport theory to describe photonic transport in photonic networks. The photonic networks concerned in the paper consist of all-optical circuits incorporating photonic bandgap waveguides and driven resonators. The photoncurrents flowing through waveguides are entirely determined from the exact master equation of the driven resonators. The master equation of the driven resonators is obtained by explicitly eliminating all the waveguide degrees of freedom while the back-reactions between resonators and waveguides are fully taken into account. The relations between the driven photonic dynamics and photoncurrents are obtained. The quantum dissipation and quantum noise effects in photonic transport are also fully addressed. As an illustration, the theory is applied to the transport phenomena of a driven nanocavity coupled to two waveguides in photonic crystals. The controllability of photonic transport through the driven resonator is demonstrated.

  15. Two-Dimentional Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Dridi, Kim

    1999-01-01

    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......In the recent years a new class of periodic high-index contrast dielectric structures, known as photonic bandgap structures, has been discovered. In these structures frequency intervals, known as photonic bandgaps, where propagation of electromagnetic waves is not allowed, exist due to the periodic...... 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...

  16. All-solid very large mode area ytterbium-doped silica microstructured fiber based on accurate control on cladding index.

    Science.gov (United States)

    Wei, Huifeng; Chen, Kangkang; Yang, Yucheng; Li, Jinyan

    2016-04-18

    We have demonstrated a new approach for developing very large mode area silica-based microstructured Ytterbium (Yb)-doped fibers. The microstructured region acting as pump cladding around the core is composed by periodically arranged low-index Fluorine-doped silica inclusions with an extremely low filling ratio of 0.088. To the best of our knowledge, we achieved the most accurate controlling on cladding index by 1 × 10-5 via our passively doped cladding (PDC) method. Two fibers with 127μm and 50μm core diameter respectively were fabricated from the same final preform designed by this approach. It is verified that our 50μm core diameter fiber can maintain robust single mode behavior at 1064nm wavelength. The advantage of an all-solid structure along with a much simpler fabrication process makes our approach very suitable for realizing very large mode area fibers for high power fiber laser application.

  17. 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.

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

    Directory of Open Access Journals (Sweden)

    Tapani Ryhänen

    2012-08-01

    Full Text Available 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 secondary batteries reported. The bending radius of such a textile battery is less than 1.5 mm while lightening up an LED. This new material combination and inherent flexibility is well suited to provide an energy source for future wearable and woven electronics.

  19. 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.

  20. 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

  1. High-performance flexible all-solid-state supercapacitors based on densely-packed graphene/polypyrrole nanoparticle papers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chao; Zhang, Liling [Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, School of Electronics, Information and Electrical Engineering, Shanghai Jiao Tong University, Dong Chuan Road No. 800, Shanghai, 200240 (China); Hu, Nantao, E-mail: hunantao@sjtu.edu.cn [Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, School of Electronics, Information and Electrical Engineering, Shanghai Jiao Tong University, Dong Chuan Road No. 800, Shanghai, 200240 (China); Yang, Zhi; Wei, Hao [Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, School of Electronics, Information and Electrical Engineering, Shanghai Jiao Tong University, Dong Chuan Road No. 800, Shanghai, 200240 (China); Wang, Yanyan, E-mail: yywang@suda.edu.cn [College of Physics, Optoelectronics and Energy, Soochow University, Suzhou, 215006 (China); Zhang, Yafei, E-mail: yfzhang@sjtu.edu.cn [Key Laboratory for Thin Film and Microfabrication Technology of the Ministry of Education, School of Electronics, Information and Electrical Engineering, Shanghai Jiao Tong University, Dong Chuan Road No. 800, Shanghai, 200240 (China)

    2016-11-30

    Highlights: • The addition of methyl orange can affect the size of polypyrrole nanoparticles. • The flexible hybrid paper has a highly-interconnected sandwich framework. • The hybrid paper shows a high areal and volumetric specific capacitance. • Flexible all-solid-state supercapacitor exhibits excellent capacitive performances. - Abstract: Graphene-based all-solid-state supercapacitors (ASSSCs) have received increasing attention. It’s a great challenge to fabricate high-performance flexible solid-state supercapacitors with high areal and volumetric energy storage capability, superior electron and ion conductivity, robust mechanical flexibility, as well as long term stability. Herein, we report a facile method to fabricate flexible ASSSCs based on densely-packed reduced graphene oxide (rGO)/polypyrrole nanoparticle (PPy NP) hybrid papers with a sandwich framework, which consists of well-separated and continuously-aligned rGO sheets. The incorporation of PPy NPs not only provides pseudocapacitance but also facilitates the infiltration of gel electrolyte. The assembled ASSSCs possess maximum areal and volumetric specific capacitances of 477 mF/cm{sup 2} and 94.9 F/cm{sup 3} at 0.5 mA/cm{sup 2}. They also exhibit little capacitance deviation under different bending states, excellent cycling stability, small leakage current and low self-discharge characteristics. Additionally, the maximum areal and volumetric energy densities of 132.5 μWh/cm{sup 2} and 26.4 mWh/cm{sup 3} are achieved, which indicate that this hybrid paper is a promising candidate for high-performance flexible energy storage devices.

  2. 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.

  3. 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

    2016-08-09

    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.

  4. 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

    2016-07-21

    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.

  5. Oxygen-Activated Growth and Bandgap Tunability of Large Single-Crystal Bilayer Graphene

    Science.gov (United States)

    Hao, Yufeng; Hone, James; Ruoff, Rodney; Colombo, Luigi; the Hone Group Team

    Distinct from zero-bandgap single-layer graphene, Bernal-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. In this presentation, we will focus on the most recent progress in the identification of new growth mechanisms towards large-area single-layer BLG on Copper: multiple control experiments and first-principles calculations are used to support the proposed mechanisms. We emphasize that trace amount of impurities on metal surface are critical to initiate graphene growth and affect the growth kinetics. Furthermore, contrary to the traditional viewpoint that graphene growth is always surface-limited process, our new observations strongly suggest that metal bulk plays a role to feed carbon species for graphene growth. State-of-the-art structural characterizations and electrical transport measurements of the CVD graphene layers will be presented as well.

  6. First principle analyses of direct bandgap solar cells with absorbing substrates versus mirrors

    Science.gov (United States)

    Kirk, Alexander P.; Kirk, Wiley P.

    2013-11-01

    Direct bandgap InP, GaAs, CdTe, and Ga0.5In0.5P solar cells containing backside mirrors as well as parasitically absorbing substrates are analyzed for their limiting open circuit voltage and power conversion efficiency with comparison to record solar cells. From the principle of detailed balance, it is shown quantitatively that mirror solar cells have greater voltage and power conversion efficiency than their substrate counterparts. Next, the radiative recombination coefficient and maximum radiative lifetime of GaAs mirror and substrate solar cells are calculated and compared to the nonradiative Auger and Shockley-Read-Hall (SRH) lifetimes. Mirror solar cells have greater radiative lifetime than their substrate variants. Auger lifetime exceeds radiative lifetime for both substrate and mirror cells while SRH lifetime may be less or greater than radiative lifetime depending on trap concentration and capture cross section. Finally, the change in free energy of the photogenerated carriers is analyzed in a comparison between InP, GaAs, CdTe, and Ga0.5In0.5P mirror and substrate solar cells in order to characterize the relationship between solar photon quality and free energy management in solar cells with differing bandgaps. Wider bandgap visible threshold Ga0.5In0.5P solar cells make better use of the available change in free energy of the photogenerated charge carriers, even when normalized to the bandgap energy, than narrower bandgap near-IR threshold InP, GaAs, and CdTe solar cells.

  7. A leap over Dirac cones in one-dimensional graphene-based photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Jahani, D., E-mail: dariush110@gmail.com [Young Researchers and Elite Club, Kermanshah branch, Islamic Azad University, Kermanshah (Iran, Islamic Republic of); Abaspour, L.; Soltani-Vala, A.; Barvestani, J. [Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2016-06-15

    The existence of a photonic bandgap in the visible range of light spectrum corresponding to a 1D graphene-based photonic crystal which recently has been proposed and is formed by embedding alternatively graphene layers into a dielectric background is investigated in this paper. By the use of the complete form of optical conductivity for the full expression of the tight-binding Hamiltonian of graphene layer, we numerically demonstrate an appeared bandgap in the visible region of the spectrum which can open up new route for further high-frequency applications of graphene-based photonic devices. It is revealed that the associated bandgap could be altered by changing the hopping energy and the amount of chemical potential leading to broadening the forbidden frequency regions with further increasing. Finally, it is also shown that the tunability feature of the photonic bandgap could be affected by changing the hopping energy.

  8. Frequency conversion through spontaneous degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin;

    2014-01-01

    Frequency conversion through spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers. Different FWM processes are observed, phasematching between fiber modes of orthogonal polarization, intermodal phasematching across bandgaps, and intramodal...

  9. 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.

  10. 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.

  11. 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

  12. Study on All-Solid-State Chloride Sensor Based on Tin Oxide/Indium Tin Oxide Glass

    Science.gov (United States)

    Cheng, Jui-Fu; Chou, Jung-Chuan; Sun, Tai-Ping; Hsiung, Shen-Kan; Kao, Hui-Ling

    2011-03-01

    An all-solid-state chloride electrode based on a tin oxide (SnO2)/indium tin oxide (ITO) glass was developed in this study. The sensing membrane of the electrode was prepared by mixing poly(vinyl chloride) (PVC), bis(2-ethylhexyl) sebacate (DOS), [4,5-dimethy-l-3,6-bis(dodecyloxy)-1,2-phenylene] bis(mercury chloride) (ETH9033), and tridodecylmethyl ammonium chloride (TDDMACl). The mixed solution was mixed with tetrahydrofuran (THF), and then dropped on the sensing window of SnO2/ITO glass. According to the experimental results, the optimal weight ratio were PVC:DOS:ETH9033:TDDMACl=33:66:2:5. At this optimum weight ratio, the sensitivity was 54 mV/dec while the range of linear concentrations of NaCl solutions was between 10-4 and 1 M. The lower detection limit of the sensor reached 8×10-5 M and the response time was less than 1 s. The selectivity coefficient was consistent with the theory of Hofmeister lipophilicity. The lifetime was over 60 days and the repeatability was over 50 times. Moreover, the chloride ion sensor was successfully applied to detecting chloride ions in rinsing solutions for contact lenses, and the experimental results revealed that the correlation coefficient was 0.99.

  13. 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.

  14. High-performance all-solid state asymmetric supercapacitor based on Co3O4 nanowires and carbon aerogel

    Science.gov (United States)

    Liu, Weiwei; Li, Xin; Zhu, Menghua; He, Xiong

    2015-05-01

    An all-solid state asymmetric supercapacitor has been fabricated using carbon aerogel (CA) microspheres as the negative electrode and Co3O4 nanowires on nickel foam (Co3O4-NF) as the positive electrode separated by PVA-KOH membrane as the electrolyte. For the desirable porous structure, high specific capacitance and rate capability of CA and Co3O4-NF, broader potential window of the two electrodes, no binder and conductive agent added, the asymmetric supercapacitor can be cycled reversibly in a wide potential window of 0-1.5 V with an energy density of 17.9 Wh kg-1 at a power density of 750 W kg-1. The energy density of the asymmetric supercapacitor is significantly improved in comparison with those of the symmetric supercapacitors based on CA (6.28 Wh kg-1) and Co3O4-NF (2.42 Wh kg-1). The asymmetric supercapacitor can also deliver a high energy density of 10.44 Wh kg-1, even at a high power density of 7.5 kW kg-1. In addition, the asymmetric device shows good stability with approximately 85% of its initial capacitance after 1000 cycles.

  15. Development and characterization of an all-solid-state potentiometric biosensor array microfluidic device for multiple ion analysis.

    Science.gov (United States)

    Liao, Wei-Yin; Weng, Chen-Hsun; Lee, Gwo-Bin; Chou, Tse-Chuan

    2006-10-01

    A microfluidic device with an all-solid-state potentiometric biosensor array was developed using microfabrication technology. The sensor array included a pH indicator, and potassium and calcium ion-selective microelectrodes. The pH indicator was an iridium oxide thin film modified platinum microelectrode and the iridium oxide was deposited by an electrochemical method. The potassium and calcium ion-selective microelectrodes were platinum coated with silicon rubber based ion-selective membranes with respectively potassium (valinomycin) and calcium (ETH 1001) ionophores. The detection system was integrated with a micro-pneumatic pump which can continuously drive fluids into the microchannel through sensors at flow rates ranging from 52.4 microl min(-1) to 7.67 microl min(-1). The sensor array microfluidic device showed near-Nernstian responses with slopes of 62.62 mV +/- 2.5 mV pH(-1), 53.76 mV +/- 3 mV -log[K+](-1) and 25.77 mV +/- 2 mV -log[Ca2+](-1) at 25 degrees C +/- 5 degrees C, and a linear response within the pH range of 2-10, with potassium and calcium concentrations between 0.1 M and 10(-6) M. In this study the device provided a convenient way to measure the concentration of hydrogen, potassium and calcium ions, which are important physiological parameters.

  16. In situ and nonvolatile photoluminescence tuning and nanodomain writing demonstrated by all-solid-state devices based on graphene oxide.

    Science.gov (United States)

    Tsuchiya, Takashi; Tsuruoka, Tohru; Terabe, Kazuya; Aono, Masakazu

    2015-02-24

    In situ and nonvolatile tuning of photoluminescence (PL) has been achieved based on graphene oxide (GO), the PL of which is receiving much attention because of various potential applications of the oxide (e.g., display, lighting, and nano-biosensor). The technique is based on in situ and nonvolatile tuning of the sp(2) domain fraction to the sp(3) domain fraction (sp(2)/sp(3) fraction) in GO through an electrochemical redox reaction achieved by solid electrolyte thin films. The all-solid-state variable PL device was fabricated by GO and proton-conducting mesoporous SiO2 thin films, which showed an extremely low PL background. The device successfully tuned the PL peak wavelength in a very wide range from 393 to 712 nm, covering that for chemically tuned GO, by adjusting the applied DC voltage within several hundred seconds. We also demonstrate the sp(2)/sp(3) fraction tuning using a conductive atomic force microscope. The device achieved not only writing, but also erasing of the sp(2)/sp(3)-fraction-tuned nanodomain (both directions operation). The combination of these techniques is applicable to a wide range of nano-optoelectronic devices including nonvolatile PL memory devices and on-demand rewritable biosensors that can be integrated into nano- and microtips which are transparent, ultrathin, flexible, and inexpensive.

  17. 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.

  18. High-performance flexible all-solid-state supercapacitors based on densely-packed graphene/polypyrrole nanoparticle papers

    Science.gov (United States)

    Yang, Chao; Zhang, Liling; Hu, Nantao; Yang, Zhi; Wei, Hao; Wang, Yanyan; Zhang, Yafei

    2016-11-01

    Graphene-based all-solid-state supercapacitors (ASSSCs) have received increasing attention. It's a great challenge to fabricate high-performance flexible solid-state supercapacitors with high areal and volumetric energy storage capability, superior electron and ion conductivity, robust mechanical flexibility, as well as long term stability. Herein, we report a facile method to fabricate flexible ASSSCs based on densely-packed reduced graphene oxide (rGO)/polypyrrole nanoparticle (PPy NP) hybrid papers with a sandwich framework, which consists of well-separated and continuously-aligned rGO sheets. The incorporation of PPy NPs not only provides pseudocapacitance but also facilitates the infiltration of gel electrolyte. The assembled ASSSCs possess maximum areal and volumetric specific capacitances of 477 mF/cm2 and 94.9 F/cm3 at 0.5 mA/cm2. They also exhibit little capacitance deviation under different bending states, excellent cycling stability, small leakage current and low self-discharge characteristics. Additionally, the maximum areal and volumetric energy densities of 132.5 μWh/cm2 and 26.4 mWh/cm3 are achieved, which indicate that this hybrid paper is a promising candidate for high-performance flexible energy storage devices.

  19. 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.

  20. Modification of Absorption of a Bulk Material by Photonic Crystals

    Institute of Scientific and Technical Information of China (English)

    席永刚; 王昕; 胡新华; 刘晓晗; 资剑

    2002-01-01

    We show theoretically that it is possible to modify absorption of a bulk absorbing material by inserting another non-absorbing dielectric slab periodically to form one-dimensional photonic crystals. It is found that, for fre- quencies within photonic bandgaps, absorption is always suppressed. For frequencies located at photonic bands, absorption can be suppressed or enhanced, which depends on the relative values of the real refractive index of the absorbing and non-absorbing dielectric layers.

  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. Negative Refraction Angular Characterization in One-Dimensional Photonic Crystals

    OpenAIRE

    Jesus Eduardo Lugo; Rafael Doti; Jocelyn Faubert

    2011-01-01

    BACKGROUND: Photonic crystals are artificial structures that have periodic dielectric components with different refractive indices. Under certain conditions, they abnormally refract the light, a phenomenon called negative refraction. Here we experimentally characterize negative refraction in a one dimensional photonic crystal structure; near the low frequency edge of the fourth photonic bandgap. We compare the experimental results with current theory and a theory based on the group velocity d...

  3. Photonic Band Gap Structures with Periodically Arranged Atoms in a Two-Dimensional Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    LI Zhi-Yu; CHEN Fang; ZHOU Jian-Ying

    2005-01-01

    @@ Linear transmission, reflection and absorption spectra for a new two-dimensional photonic crystal with periodically arranged resonant atoms are examined. Numerical results show that a twin-gap structure with forbidden bands displaced from a non-doped bandgap structure can be produced as a result of atomic polarization. The absorption spectrum is also significantly altered compared to the single atom entity.

  4. Simultaneous multi-frequency topological edge modes between one-dimensional photonic crystals.

    Science.gov (United States)

    Choi, Ka Hei; Ling, C W; Lee, K F; Tsang, Y H; Fung, Kin Hung

    2016-04-01

    We show theoretically that, in the limit of weak dispersion, one-dimensional binary centrosymmetric photonic crystals can support topological edge modes in all photonic bandgaps. By analyzing their bulk band topology, these "harmonic" topological edge modes can be designed in a way that they exist at all photonic bandgaps opened at the center of the Brillouin zone, at all gaps opened at the zone boundaries, or both. The results may suggest a new approach to achieve robust multi-frequency coupled modes for applications in nonlinear photonics, such as frequency upconversion.

  5. 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.

  6. INVESTIGATION ON EMI EFFECTS IN BANDGAP VOLTAGE REFERENCES

    OpenAIRE

    Fiori, Franco; Crovetti S., Paolo

    2002-01-01

    International audience; In this paper the susceptibility of integrated bandgap voltage references to Electromagnetic Interference (EMI) is investigated by on-chip measurements carried out on Kuijk and Tsividis bandgap circuits. These measurements highlight the offset in the reference voltage induced by continuous wave (CW) EMI and the complete failures which may be experienced by bandgap circuits. The role of the susceptibility of the startup circuit and of the operational amplifier which are...

  7. Direct-indirect character of the bandgap in methylammonium lead iodide perovskite

    Science.gov (United States)

    Hutter, Eline M.; Gélvez-Rueda, María C.; Osherov, Anna; Bulović, Vladimir; Grozema, Ferdinand C.; Stranks, Samuel D.; Savenije, Tom J.

    2017-01-01

    Metal halide perovskites such as methylammonium lead iodide (CH3NH3PbI3) are generating great excitement due to their outstanding optoelectronic properties, which lend them to application in high-efficiency solar cells and light-emission devices. However, there is currently debate over what drives the second-order electron-hole recombination in these materials. Here, we propose that the bandgap in CH3NH3PbI3 has a direct-indirect character. Time-resolved photo-conductance measurements show that generation of free mobile charges is maximized for excitation energies just above the indirect bandgap. Furthermore, we find that second-order electron-hole recombination of photo-excited charges is retarded at lower temperature. These observations are consistent with a slow phonon-assisted recombination pathway via the indirect bandgap. Interestingly, in the low-temperature orthorhombic phase, fast quenching of mobile charges occurs independent of the temperature and photon excitation energy. Our work provides a new framework to understand the optoelectronic properties of metal halide perovskites and analyse spectroscopic data.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids.

    Science.gov (United States)

    Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Zhang, Kailiang; Liu, Bo; Yao, Jianquan

    2015-08-15

    A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The tapered all-solid WAF is fabricated by using a fusion splicer, and the sensor is formed by immersing the tapered all-solid WAF into the MF. The transmission spectra have been measured and analyzed under different magnetic-field intensities. Experimental results show that the acquired magnetic-field sensitivity is 44.57 pm/Oe for a linear magnetic-field intensity range from 50 to 200 Oe. All-solid WAF has very similar thermal expansion coefficient for high- and low-refractive-index glasses, so mode profile is not affected by thermal drifts. Also, magnetically induced refractive-index changes into the ferrofluid are of the order of ∼5×10(-2), while the corresponding thermally induced refractive-index changes into the ferrofluid are expected to be lower. The temperature response has also been detected, and the temperature-induced wavelength shift perturbation is less than 0.3 nm from temperature of 26.9°C-44°C. The proposed magnetic-field sensor has such advantages as low temperature sensitivity, simple structure, and ease of fabrication. It also indicates that the magnetic-field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field.

  13. Correlation of Bandgap Reduction with Inversion Response in (Si)GeSn/High-k/Metal Stacks.

    Science.gov (United States)

    Schulte-Braucks, C; Narimani, K; Glass, S; von den Driesch, N; Hartmann, J M; Ikonic, Z; Afanas'ev, V V; Zhao, Q T; Mantl, S; Buca, D

    2017-03-15

    The bandgap tunability of (Si)GeSn group IV semiconductors opens a new era in Si-technology. Depending on the Si/Sn contents, direct and indirect bandgaps in the range of 0.4-0.8 eV can be obtained, offering a broad spectrum of both photonic and low power electronic applications. In this work, we systematically studied capacitance-voltage characteristics of high-k/metal gate stacks formed on GeSn and SiGeSn alloys with Sn-contents ranging from 0 to 14 at. % and Si-contents from 0 to 10 at. % particularly focusing on the minority carrier inversion response. A clear correlation between the Sn-induced shrinkage of the bandgap energy and enhanced minority carrier response was confirmed using temperature and frequency dependent capacitance voltage-measurements, in good agreement with k.p theory predictions and photoluminescence measurements of the analyzed epilayers as reported earlier. The enhanced minority generation rate for higher Sn-contents can be firmly linked to the bandgap reduction in the GeSn epilayer without significant influence of substrate/interface effects. It thus offers a unique possibility to analyze intrinsic defects in (Si)GeSn epilayers. The extracted dominant defect level for minority carrier inversion lies approximately 0.4 eV above the valence band edge in the studied Sn-content range (0-12.5 at. %). This finding is of critical importance since it shows that the presence of Sn by itself does not impair the minority carrier lifetime. Therefore, the continuous improvement of (Si)GeSn material quality should yield longer nonradiative recombination times which are required for the fabrication of efficient light detectors and to obtain room temperature lasing action.

  14. 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......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 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....

  15. 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

  16. 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.

  17. Phonon-assisted coherent control of injected carriers in indirect bandgap semiconductors

    Science.gov (United States)

    Rioux, Julien; Nastos, Fred; Sipe, John E.

    2007-03-01

    Charge and spin currents can be generated in direct semiconductors by quantum interference between one- and two-photon absorption. For semiconductors such as Si and Ge, optical injection of carriers over the indirect bandgap must be assisted by momentum transfer from phonon scattering. We consider the optical properties for such 1+2 photon processes in the presence of the electron-phonon interaction. The latter is modelled by acoustic deformation potential. Indirect transitions involve double Brillouin zone integrations, which are computed by a linearized tetrahedron method. We compare our results to those for bulk GaAs. M.J. Stevens, R.D.R. Bhat, A. Najmaie, H.M. van Driel, J.E. Sipe and A.L. Smirl, in Optics of Semiconductors and Their Nanostructures, edited by H. Kalt and M. Hetterich (Springer, Berlin, 2004), vol. 146 of Springer Series in Solid-State Sciences, p. 209.

  18. 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%).

  19. 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.

  20. Nonlocal hyperconcentration on entangled photons using photonic module system

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Cong; Wang, Tie-Jun; Mi, Si-Chen [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhang, Ru [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Ethnic Minority Education, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Wang, Chuan, E-mail: wangchuan@bupt.edu.cn [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2016-06-15

    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.

  1. Ultrafast electron and hole transfer in bulk heterojunctions of low-bandgap polymers

    Science.gov (United States)

    Kozlov, Oleg V.; Pavelyev, Vlad G.; de Gier, Hilde D.; Havenith, Remco W. A.; van Loosdrecht, Paul H. M.; Hummelen, Jan C.; Pshenichnikov, Maxim S.

    2016-12-01

    In modern bulk heterojunction (BHJ) organic solar cells, blends of low-bandgap polymer and [70]PCBM acceptor are used in the active layer. In this combination, the polymer absorbs photons from the red and near-IR parts of the solar spectrum, while the blue and near-UV photons are harvested by [70]PCBM. As a result, both electron transfer from polymer to [70]PCBM and hole transfer from [70]PCBM to polymer are of utmost importance in free charge generation and have to be optimized simultaneously. Here we study electron and hole transfer processes in BHJ blends of two low-bandgap polymers, BTT-DPP and PCPDTBT, by ultrafast photoinduced spectroscopy (PIA). By tracking the PIA dynamics, we observed substantially different charge separation pathways in BHJs of the two polymers with [70]PCBM. From the photoinduced anisotropy dynamics, we demonstrated that in the PCPDTBT:[70]PCBM system both electron and hole transfer processes are highly efficient, while in the BTTBPP:[ 70]PCBM electron transfer is blocked due to the unfortunate energy level alignment leaving hole transfer the only pathway to free charge generation. Calculations at the density functional theory level are used to gain more insight into our findings. The presented results highlight the importance of the energy level alignment on the charge separation process.

  2. 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.

  3. Patterning of lithium lanthanum titanium oxide films by soft lithography as electrolyte for all-solid-state Li-ion batteries

    NARCIS (Netherlands)

    Kokal, I.; Gobel, O.F.; Ham, van den E.J.; Elshof, ten J.E.; Notten, P.H.L.; Hintzen, H.T.

    2015-01-01

    The combination of sol–gel processing and soft-lithographic patterning presents a promising route towards three-dimensional (3D) micro Li-ion electrodes, and may offer a viable approach for the fabrication of all-solid-state 3D Li-ion batteries. The methods are relatively simple and therefore cheap

  4. 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,

  5. Investigating the all-solid-state batteries based on lithium garnets and a high potential cathode - LiMn1.5Ni0.5O4.

    Science.gov (United States)

    Hänsel, Christian; Afyon, Semih; Rupp, Jennifer L M

    2016-11-03

    All-solid-state Li-ion batteries based on lithium garnets give new prospects for safer battery operations avoiding liquids, and could enable the integration of high energy density electrode materials. Herein, we critically investigate the structural and chemical stability of the high voltage cathode material, LiMn1.5Ni0.5O4, based on the solid lithium garnet electrolyte LLZO (c-Li6.4Ga0.2La3Zr2O12) for all-solid Li-ion batteries. We manufacture battery cells based on nano-grained synthesized LLZO and composite cathodes (LiMn1.5Ni0.5O4/LLZO/C) fabricated via direct slurry casting of the cathode material and additives on sintered LLZO pellets against metallic Li anodes. The galvanostatic tests of such all-solid-state batteries up to 4.9 V at 95 °C reveal the incompatibility of the solid electrolyte and the cathode material under given conditions. Post-mortem analyses of the all-solid-state batteries demonstrate the formation of new inactive phases at the LLZO/LiMn1.5Ni0.5O4 interfacial region through an irreversible reaction starting at ∼3.8 V during charging. The discovered limited chemical stability under the investigated conditions raises the question if LLZO could be a promising solid-electrolyte for future all-solid-state Li-ion batteries especially at higher operation potentials and demanding operation conditions.

  6. 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.

  7. Optimum design of band-gap beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    -sectional area. To study the band-gap for travelling waves, a repeated inner segment of the optimized beams is analyzed using Floquet theory and the waveguide finite element (WFE) method. Finally, the frequency response is computed for the optimized beams when these are subjected to an external time......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...

  8. 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

  9. 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...

  10. 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.

  11. Photonic crystal fiber with a hybrid honeycomb cladding

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Nielsen, Martin Dybendal; Folkenberg, Jacob Riis;

    2004-01-01

    be formed by manipulating the cladding region ratherthan the core region itself. Germanium-doping of the honeycomb lattice has recently been suggested for the formation of a photonic band-gap guiding silica-core and here we experimentally demonstrate how an index-guiding silica-core can be formed...

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. High-power and high-efficiency operation of an all-solid-state,quasi-continuous-wave,titanium sapphire laser system

    Institute of Scientific and Technical Information of China (English)

    Quanfu Wei(魏权夫); Xin Ding(丁欣); Wuqi Wen(温午麒); Lijuan Fan(范丽娟); Jianquan Yao(姚建铨)

    2004-01-01

    High-power and high-efficiency operation of an all-solid-state, quasi-continuous-wave, titanium sapphire laser is obtained with a diode-laser-pumped frequency-doubled Nd:YAG laser as the pump source. A maximum output power of 2.5 W is obtained for 16-W power of 532-nm pump light. A much higher conversion efficiency of 15.7% is obtained when at the maximum output power.

  19. 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.

  20. 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.

  1. All-solid, flexible solar textiles based on dye-sensitized solar cells with ZnO nanorod arrays on stainless steel wires

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Youngjin [Department of Clothing and Textiles, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Park, Jung Tae; Koh, Jong Kwan [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Jong Hak, E-mail: jonghak@yonsei.ac.kr [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Eunae, E-mail: eakim@yonsei.ac.kr [Department of Clothing and Textiles, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2013-10-01

    Highlights: • All-solid, flexible solar textile fabricated with DSSCs is demonstrated. • DSSCs woven into a satin structure and transparent PET film are used. • Solar textile showed a high efficiency of 2.57%. -- Abstract: An all-solid, flexible solar textile fabricated with dye-sensitized solar cells (DSSCs) woven into a satin structure and transparent poly(ethylene terephthalate) (PET) film was demonstrated. A ZnO nanorod (NR) vertically grown from fiber-type conductive stainless steel (SS) wire was utilized as a photoelectrode, and a Pt-coated SS wire was used as a counter electrode. A graft copolymer, i.e. poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom transfer radical polymerization (ATRP) and used as a solid electrolyte. The conditions for the growth of ZnO NR and sufficient dye loading were investigated to improve cell performance. The adhesion of PET films to DSSCs resulted in physical stability improvements without cell performance loss. The solar textile with 10 × 10 wires exhibited an energy conversion efficiency of 2.57% with a short circuit current density of 20.2 mA/cm{sup 2} at 100 mW/cm{sup 2} illumination, which is the greatest account of an all-solid, ZnO-based flexible solar textile. DSSC textiles with woven structures are applicable to large-area, roll-to-roll processes.

  2. In Situ Atomic-Scale Observation of Electrochemical Delithiation Induced Structure Evolution of LiCoO2 Cathode in a Working All-Solid-State Battery.

    Science.gov (United States)

    Gong, Yue; Zhang, Jienan; Jiang, Liwei; Shi, Jin-An; Zhang, Qinghua; Yang, Zhenzhong; Zou, Dongli; Wang, Jiangyong; Yu, Xiqian; Xiao, Ruijuan; Hu, Yong-Sheng; Gu, Lin; Li, Hong; Chen, Liquan

    2017-03-29

    We report a method for in situ atomic-scale observation of electrochemical delithiation in a working all-solid-state battery using a state-of-the-art chip based in situ transmission electron microscopy (TEM) holder and focused ion beam milling to prepare an all-solid-state lithium-ion battery sample. A battery consisting of LiCoO2 cathode, LLZO solid state electrolyte and gold anode was constructed, delithiated and observed in an aberration corrected scanning transmission electron microscope at atomic scale. We found that the pristine single crystal LiCoO2 became nanosized polycrystal connected by coherent twin boundaries and antiphase domain boundaries after high voltage delithiation. This is different from liquid electrolyte batteries, where a series of phase transitions take place at LiCoO2 cathode during delithiation. Both grain boundaries become more energy favorable along with extraction of lithium ions through theoretical calculation. We also proposed a lithium migration pathway before and after polycrystallization. This new methodology could stimulate atomic scale in situ scanning/TEM studies of battery materials and provide important mechanistic insight for designing better all-solid-state battery.

  3. 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.

  4. 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.

  5. 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

  6. Metallic photonic crystals for thermophotovoltaic applications

    Science.gov (United States)

    Walsh, Timothy A.

    Since the idea of a photonic bandgap was proposed over two decades ago, photonic crystals have been the subject of significant interest due to their novel optical properties which enable new and varied applications. In this research, the photonic bandgap effect is exploited to tailor the thermal radiation spectrum to a narrow range of wavelengths determined by the lattice symmetry and dimensions of the photonic crystal structure. This sharp emission peak can be matched to the electronic bandgap energy of a p-n junction photovoltaic cell for high efficiency thermophotovoltaic energy conversion. This thesis explores aspects of photonic crystal design, materials considerations, and manufacture for thermophotovoltaic applications. Photonic crystal structures come in many forms, exhibiting various types of 1D, 2D, and 3D lattice symmetry. In this work, the "woodpile" 3D photonic crystal is studied. One advantage of the woodpile lattice is that it can be readily fabricated on a large scale using common integrated circuit manufacturing techniques. Additionally this structure lends itself to efficient and accurate modeling with the use of a plane-wave expansion based transfer matrix method to calculate the scattering properties and band structure of the photonic crystal. This method is used to explore the geometric design parameters of the woodpile structure. Optimal geometric proportions for the structure are found which yield the highest narrowband absorption peak possible. By Kirchoffs law of thermal emission, this strong and sharp absorptance will yield high power and narrowband thermal radiation. The photonic crystal thermal emission spectrum is then evaluated in a TPV system model to evaluate the electrical power density and system efficiency achievable. The results produced by the photonic crystal emitter are compared with the results assuming a blackbody thermal radiation spectrum. The blackbody represents a universal standard against which any selective emitter

  7. 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.

  8. 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.

  9. 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.

  10. Densely Aligned Graphene Nanoribbon Arrays and Bandgap Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Su, Justin [Stanford Univ., CA (United States); Chen, Changxin [Stanford Univ., CA (United States); Gong, Ming [Stanford Univ., CA (United States); Kenney, Michael [Stanford Univ., CA (United States)

    2017-01-04

    Graphene has attracted great interest for future electronics due to its high mobility and high thermal conductivity. However, a two-dimensional graphene sheet behaves like a metal, lacking a bandgap needed for the key devices components such as field effect transistors (FETs) in digital electronics. It has been shown that, partly due to quantum confinement, graphene nanoribbons (GNRs) with ~2 nm width can open up sufficient bandgaps and evolve into semiconductors to exhibit high on/off ratios useful for FETs. However, a challenging problem has been that, such ultra-narrow GNRs (~2 nm) are difficult to fabricate, especially for GNRs with smooth edges throughout the ribbon length. Despite high on/off ratios, these GNRs show very low mobility and low on-state conductance due to dominant scattering effects by imperfections and disorders at the edges. Wider GNRs (>5 nm) show higher mobility, higher conductance but smaller bandgaps and low on/off ratios undesirable for FET applications. It is highly desirable to open up bandgaps in graphene or increase the bandgaps in wide GNRs to afford graphene based semiconductors for high performance (high on-state current and high on/off ratio) electronics. Large scale ordering and dense packing of such GNRs in parallel are also needed for device integration but have also been challenging thus far. It has been shown theoretically that uniaxial strains can be applied to a GNR to engineer its bandgap. The underlying physics is that under uniaxial strain, the Dirac point moves due to stretched C-C bonds, leading to an increase in the bandgap of armchair GNRs by up to 50% of its original bandgap (i.e. bandgap at zero strain). For zigzag GNRs, due to the existence of the edge states, changes of bandgap are smaller under uniaxial strain and can be increased by ~30%. This work proposes a novel approach to the fabrication of densely aligned graphene nanoribbons with highly smooth edges afforded by anisotropic etching and uniaxial strain for

  11. Growth of Bulk Wide Bandgap Semiconductor Crystals and Their Potential Applications

    Science.gov (United States)

    Chen, Kuo-Tong; Shi, Detang; Morgan, S. H.; Collins, W. Eugene; Burger, Arnold

    1997-01-01

    Developments in bulk crystal growth research for electro-optical devices in the Center for Photonic Materials and Devices since its establishment have been reviewed. Purification processes and single crystal growth systems employing physical vapor transport and Bridgman methods were assembled and used to produce high purity and superior quality wide bandgap materials such as heavy metal halides and II-VI compound semiconductors. Comprehensive material characterization techniques have been employed to reveal the optical, electrical and thermodynamic properties of crystals, and the results were used to establish improved material processing procedures. Postgrowth treatments such as passivation, oxidation, chemical etching and metal contacting during the X-ray and gamma-ray device fabrication process have also been investigated and low noise threshold with improved energy resolution has been achieved.

  12. Photon technology. Hard photon technology; Photon technology. Hard photon gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    Research results of hard photon technology have been summarized as a part of novel technology development highly utilizing the quantum nature of photon. Hard photon technology refers to photon beam technologies which use photon in the 0.1 to 200 nm wavelength region. Hard photon has not been used in industry due to the lack of suitable photon sources and optical devices. However, hard photon in this wavelength region is expected to bring about innovations in such areas as ultrafine processing and material synthesis due to its atom selective reaction, inner shell excitation reaction, and spatially high resolution. Then, technological themes and possibility have been surveyed. Although there are principle proposes and their verification of individual technologies for the technologies of hard photon generation, regulation and utilization, they are still far from the practical applications. For the photon source technology, the laser diode pumped driver laser technology, laser plasma photon source technology, synchrotron radiation photon source technology, and vacuum ultraviolet photon source technology are presented. For the optical device technology, the multi-layer film technology for beam mirrors and the non-spherical lens processing technology are introduced. Also are described the reduction lithography technology, hard photon excitation process, and methods of analysis and measurement. 430 refs., 165 figs., 23 tabs.

  13. Direct bandgap GeSn light emitting diodes for short-wave infrared applications grown on Si

    Science.gov (United States)

    von den Driesch, Nils; Stange, Daniela; Wirths, Stephan; Rainko, Denis; Mussler, Gregor; Stoica, Toma; Ikonic, Zoran; Hartmann, Jean-Michel; Grützmacher, Detlev; Mantl, Siegfried; Buca, Dan

    2016-03-01

    The experimental demonstration of fundamental direct bandgap, group IV GeSn alloys has constituted an important step towards realization of the last missing ingredient for electronic-photonic integrated circuits, i.e. the efficient group IV laser source. In this contribution, we present electroluminescence studies of reduced-pressure CVD grown, direct bandgap GeSn light emitting diodes (LEDs) with Sn contents up to 11 at.%. Besides homojunction GeSn LEDs, complex heterojunction structures, such as GeSn/Ge multi quantum wells (MQWs) have been studied. Structural and compositional investigations confirm high crystalline quality, abrupt interfaces and tailored strain of the grown structures. While also being suitable for light absorption applications, all devices show light emission in a narrow short-wave infrared (SWIR) range. Temperature dependent electroluminescence (EL) clearly indicates a fundamentally direct bandgap in the 11 at.% Sn sample, with room temperature emission at around 0.55 eV (2.25 µm). We have, however, identified some limitations of the GeSn/Ge MQW approach regarding emission efficiency, which can be overcome by introducing SiGeSn ternary alloys as quantum confinement barriers.

  14. Self-Starting Passively Mode-Locking All-Solid-State Laser with GaAs Absorber Grown at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    JIA Yu-Lei; LING Wei-Jun; WEI Zhi-Yi; WANG Yong-Gang; MA Xiao-Yu

    2005-01-01

    @@ We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapour deposition at low temperature. With such an absorber as the output coupler in the laser resonator, laser pulses with duration of 42ps were generated at a repetition rate of 400MHz, corresponding to the average power of 590mW.

  15. 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

  16. Microwave Photonics

    OpenAIRE

    Seeds, A.J.; Liu, C. P.; T. Ismail; 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.

  17. Nitrogen-doped graphene by all-solid-state ball-milling graphite with urea as a high-power lithium ion battery anode

    Science.gov (United States)

    Liu, Chao; Liu, Xingang; Tan, Jiang; Wang, Qingfu; Wen, Hao; Zhang, Chuhong

    2017-02-01

    Nitrogen-doped graphene nanosheets (NGNS) are prepared by a novel mechanochemical method via all-solid-state ball-milling graphite with urea. The ball-milling process does not only successfully exfoliate the graphite into multi-layer (new solid doping and assist-grinding agents, has the advantages of low cost and good water solubility that can simplify the fabrication process. The as-prepared NGNS are investigated in detail by XRD, SEM, HRTEM, TGA, XPS and Raman spectroscopy. The doping nitrogens are around 3.15% and dominated (>94%) by pyrindic-N and pyrrolic-N which facilitates the NGNS with enhanced electronic conductivity and Li-ion storage capability. For the first time, we demonstrate that the all-solid-state prepared NGNS exhibits, especially at high currents, enhanced cycling stability and rate capability as Lithium ion battery (LIB) anode active material when compared to pristine graphite and undoped graphene in half-cell configuration. The method presented in this article may provide a simple, clean, economical and scalable strategy for preparation of NGNS as a feasible and promising anode material for LIBs.

  18. 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%.

  19. All-solid-state lithium secondary batteries using NiS-carbon fiber composite electrodes coated with Li₂S-P₂S₅ solid electrolytes by pulsed laser deposition.

    Science.gov (United States)

    Aso, Keigo; Sakuda, Atsushi; Hayashi, Akitoshi; Tatsumisago, Masahiro

    2013-02-01

    Composite materials including NiS active materials, sulfide-based solid electrolytes (SE), and conductive additives (VGCF: vapor grown carbon fiber) were prepared by coating a highly conductive Li(2)S-P(2)S(5) solid electrolyte onto NiS-VGCF composite using pulsed laser deposition (PLD). From scanning electron microscopy, NiS nanoparticles were on VGCF surface after coating of solid electrolytes using PLD. All-solid-state cells using the SE-coated NiS-VGCF composite and the uncoated NiS-VGCF composite were fabricated, and then the coating effects on the electrochemical performance by forming the SE thin film onto the NiS-VGCF composite were investigated. At a high current density of 3.8 mA cm(-2) (corresponding to ca. 1 C), an all-solid-state cell fabricated using the SE-coated NiS-VGCF composite as a working electrode showed the initial discharge capacity of 300 mA h g(-1), and exhibited better cycle performance than the cell using the uncoated NiS-VGCF composite.

  20. Polymer composite electrolytes having core-shell silica fillers with anion-trapping boron moiety in the shell layer for all-solid-state lithium-ion batteries.

    Science.gov (United States)

    Shim, Jimin; Kim, Dong-Gyun; Kim, Hee Joong; Lee, Jin Hong; Lee, Jong-Chan

    2015-04-15

    Core-shell silica particles with ion-conducting poly(ethylene glycol) and anion-trapping boron moiety in the shell layer were prepared to be used as fillers for polymer composite electrolytes based on organic/inorganic hybrid branched copolymer as polymer matrix for all-solid-state lithium-ion battery applications. The core-shell silica particles were found to improve mechanical strength and thermal stability of the polymer matrix and poly(ethylene glycol) and boron moiety in the shell layer increase compatibility between filler and polymer matrix. Furthermore, boron moiety in the shell layer increases both ionic conductivity and lithium transference number of the polymer matrix because lithium salt can be more easily dissociated by the anion-trapping boron. Interfacial compatibility with lithium metal anode is also improved because well-dispersed silica particles serve as protective layer against interfacial side reactions. As a result, all-solid-state battery performance was found to be enhanced when the copolymer having core-shell silica particles with the boron moiety was used as solid polymer electrolyte.

  1. Effect of Photonic Structure on Optical Properties of YVO4:Eu3+ Phosphor

    Science.gov (United States)

    Thakur, Shashi; Dhiman, Naresh; Sharma, Amit; Gathania, Arvind K.

    2016-11-01

    Polymethyl methacrylate (PMMA) photonic crystal has been prepared on quartz substrate by the self-assembly vertical deposition technique. YVO4:Eu3+ inverse opal was obtained by annealing PMMA photonic crystal infiltrated with YVO4:Eu3+ nanophosphors at 500°C for 3 h. Scanning electron microscopy confirmed the development of the photonic and inverse opal structures. Photoluminescence study showed that the luminescence characteristics depended on the position of the photonic stop band. It was observed that the photoluminescence intensity of YVO4:Eu3+ inverse opal was enhanced near the photonic stop bandgap edge as compared with the intensity of a YVO4:Eu3+ nanophosphor powder sample.

  2. Recent ROB developments on wide bandgap based UV sensors

    Science.gov (United States)

    Giordanengo, B.; Ben Moussa, A.; Hochedez, J.-F.; Soltani, A.; de Moor, P.; Minoglou, K.; Malinowski, P.; Duboz, J.-Y.; Chong, Y. M.; Zou, Y. S.; Zhang, W. J.; Lee, S. T.; Dahal, R.; Li, J.; Lin, J. Y.; Jiang, H. X.

    The next ESA spatial mission planned to study the Sun, Solar Orbiter (SO), necessitates very innovative EUV detectors. The commonly used silicon detectors suffer important limitations mainly in terms of UV robustness and dark current level. An alternative comes from diamond or III-nitride materials. In these materials, the radiation hardness, solar blindness and dark current are improved due to their wide bandgap. This paper presents the new developments on wide bandgap materials at the Royal Observatory of Belgium (ROB). We present also the LYRA instrument, the BOLD project, and the EUI instrument suite.

  3. 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

  4. Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr., C.R.; Schmid, A.W.; Marshall, K.L.

    2006-08-18

    This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time.

  5. 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...... on the positive-frequency Riemann-Silberstein vectors, is discussed. Recent attempts to understand the birth process of a photon emerging from a single atom are summarized. The polychromatic photon concept is introduced, and it is indicated how the wave mechanics of polychromatic photons can be upgraded to wave...

  6. Photoelectrochemistry, Electronic Structure, and Bandgap Sizes of Semiconducting Cu(I)-Niobates and Cu(I)-Tantalates

    Energy Technology Data Exchange (ETDEWEB)

    Maggard, Paul A.

    2013-11-14

    Semiconducting metal-oxides have remained of intense research interest owing to their potential for achieving efficient solar-driven photocatalytic reactions in aqueous solutions that occur as a result of their bandgap excitation. The photocatalytic reduction of water or carbon dioxide to generate hydrogen or hydrocarbon fuels, respectively, can be driven on p-type (photocathodic) electrodes with suitable band energies. However, metal-oxide semiconductors are typically difficult to dope as p-type with a high mobility of carriers. The supported research led to the discovery of new p-type Cu(I)-niobate and Cu(I)-tantalate film electrodes that can be prepared on FTO glass. New high-purity flux syntheses and the full structural determination of several Cu(I)-containing niobates and tantalates have been completed, as well as new investigations of their optical and photoelectrochemical properties and electronic structures via density-functional theory calculations. For example, CuNbO3, Cu5Ta11O30 and CuNb3O8 were prepared in high purity and their structures were characterized by both single-crystal and powder X-ray diffraction techniques. These two classes of Cu(I)-containing compounds exhibit optical bandgap sizes ranging from ~1.3 eV to ~2.6 eV. Photoelectrochemical measurements of these compounds show strong photon-driven cathodic currents that confirm the p-type semiconductor behavior of CuNbO3, CuNb3O8, and Cu5Ta11O30. Incident-photon-to-current efficiencies are measured that approach greater than ~1%. Electronic-structure calculations based on density functional theory reveal the visible-light absorption stems from a nearly-direct bandgap transition involving a copper-to-niobium or tantalum (d10 to d0) charge-transfer excitations.

  7. Local self-uniformity in photonic networks

    Science.gov (United States)

    Sellers, Steven R.; Man, Weining; Sahba, Shervin; Florescu, Marian

    2017-01-01

    The interaction of a material with light is intimately related to its wavelength-scale structure. Simple connections between structure and optical response empower us with essential intuition to engineer complex optical functionalities. Here we develop local self-uniformity (LSU) as a measure of a random network's internal structural similarity, ranking networks on a continuous scale from crystalline, through glassy intermediate states, to chaotic configurations. We demonstrate that complete photonic bandgap structures possess substantial LSU and validate LSU's importance in gap formation through design of amorphous gyroid structures. Amorphous gyroid samples are fabricated via three-dimensional ceramic printing and the bandgaps experimentally verified. We explore also the wing-scale structuring in the butterfly Pseudolycaena marsyas and show that it possesses substantial amorphous gyroid character, demonstrating the subtle order achieved by evolutionary optimization and the possibility of an amorphous gyroid's self-assembly. PMID:28211466

  8. 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.

  9. An all-solid state laser system for the laser ion source RILIS and in-source laser spectroscopy of astatine at ISOLDE, CERN

    CERN Document Server

    Rothe, Sebastian; Nörtershäuser, W

    This doctoral thesis describes the extension of the resonance ionization laser ion source RILIS at ISOLDE, CERN, by the addition of an all-solid state tuneable 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.

  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. 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.

  12. Effect of Poly(Ether Urethane)Introduction on the Performance of Polymer Electrolyte for All-Solid-State Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan-Fang; XIANG Wan-Chun; FANG Shi-Bi; CHEN Shen; ZHOU Xiao-Wen; ZHANG Jing-Bo; LIN Yuan

    2009-01-01

    The introduction of poly(ether urethane)(PEUR)into polymer electrolyte based on poly(ethylene oxide),LiI and I_2,has significantly increased the ionic conductivity by nearly two orders of magnitudes.An increment of I_3~- diffusion coefficient is also observed.All-solid-state dye-sensitized solar cells are constructed using the polymer electrolytes.It was found that PEUR incorporation has a beneficial effect on the enhancement of open circuit voltage V_(OC) by shifting the band edge of TiO_2 to a negative value.Scanning electron microscope images indicate the perfect interfacial contact between the TiO_2 electrode and the blend electrolyte.

  13. In Situ Tuning of Magnetization and Magnetoresistance in Fe3O4 Thin Film Achieved with All-Solid-State Redox Device.

    Science.gov (United States)

    Tsuchiya, Takashi; Terabe, Kazuya; Ochi, Masanori; Higuchi, Tohru; Osada, Minoru; Yamashita, Yoshiyuki; Ueda, Shigenori; Aono, Masakazu

    2016-01-26

    An all-solid-state redox device composed of Fe3O4 thin film and Li(+) ion conducting solid electrolyte was fabricated for use in tuning magnetization and magnetoresistance (MR), which are key factors in the creation of high-density magnetic storage devices. Electrical conductivity, magnetization, and MR were reversibly tuned by Li(+) insertion and removal. Tuning of the various Fe3O4 thin film properties was achieved by donation of an electron to the Fe(3+) ions. This technique should lead to the development of spintronics devices based on the reversible switching of magnetization and spin polarization (P). It should also improve the performance of conventional magnetic random access memory (MRAM) devices in which the ON/OFF ratio has been limited to a small value due to a decrease in P near the tunnel barrier.

  14. 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...... weakening of hydrogen bonds at 82 C seems to be coupled with the onset of orientational or rotational disorder of the ions. The temperature dependence of ionic conductivity in the solid and molten states is measured via impedance spectroscopy and current interruption technique, respectively. The Arrhenius......), 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...

  15. 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.

  16. AlN Bandgap Temperature Dependence from its Optical Properties

    Science.gov (United States)

    2008-06-07

    AlN bandgap temperature dependence from its optical properties E. Silveira a,, J.A. Freitas b, S.B. Schujman c, L.J. Schowalter c a Depto. de Fisica ...range. The energy gap in semiconductors in general changes due to contributions from the electron–phonon interaction and due to the lattice thermal

  17. 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...

  18. Automating Energy Bandgap Measurements in Semiconductors Using LabVIEW

    Science.gov (United States)

    Garg, Amit; Sharma, Reena; Dhingra, Vishal

    2010-01-01

    In this paper, we report the development of an automated system for energy bandgap and resistivity measurement of a semiconductor sample using Four-Probe method for use in the undergraduate laboratory of Physics and Electronics students. The automated data acquisition and analysis system has been developed using National Instruments USB-6008 DAQ…

  19. 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.

  20. Semi-interpenetrating solid polymer electrolyte based on thiol-ene cross-linker for all-solid-state lithium batteries

    Science.gov (United States)

    Suk, Jungdon; Lee, Yu Hwa; Kim, Do Youb; Kim, Dong Wook; Cho, Song Yun; Kim, Ji Man; Kang, Yongku

    2016-12-01

    We developed highly promising solid polymer electrolytes (SPEs) based on a novel cross-linker containing star-shaped phosphazene with poly(ethylene oxide) (PEO) branches with very high ionic conductivity (7.6 × 10-4 S cm-1), improved mechanical stability, and good electrochemical stability for all-solid-state lithium batteries. In particular, allyl groups were introduced at the ends of the cross-linker in order to overcome the easy self-polymerization of existing cross-linking acrylate end groups. A novel semi-interpenetrating network (semi-IPN) SPE was prepared by in-situ radical polymerization of a precursor solution containing lithium salt, poly(ethylene glycol) dimethyl ether as a plasticizer, and a mixture of pentaerythritol tetrakis(3-mercaptopropionate) and a synthesized hexakis(allyloxy)cyclotriphosphazene (thiol-ene PAL) as the cross-linker. Batteries employing LiFePO4 as the cathode, lithium foil as the anode, and the SPE thin film as the electrolyte were assembled and tested. At ambient temperature, the initial discharge capacity was 147 mAh/g at 0.1 °C and 132 mAh/g at 0.5 °C, and 97% of the capacity was retained at the 100th cycle. All-solid-state pouch-package lithium cells assembled with the SPEs exhibited stable electrochemical performance, even under a severely wrinkled state. These outstanding properties of SPEs based on thiol-ene PAL demonstrate feasibility for practical battery applications with improved reliability and safety.

  1. An all-solid-state microsecond-range quasi-square pulse generator based on fractional-turn ratio saturable pulse transformer and anti-resonance network

    Science.gov (United States)

    Chen, Rong; Yang, Jianhua; Cheng, Xinbing; Pan, Zilong

    2017-03-01

    High voltage pulse generators are widely applied in a number of fields. Defense and industrial applications stimulated intense interests in the area of pulsed power technology towards the system with high power, high repetition rate, solid state characteristics, and compact structure. An all-solid-state microsecond-range quasi-square pulse generator based on a fractional-turn ratio saturable pulse transformer and anti-resonance network is proposed in this paper. This generator consists of a charging system, a step-up system, and a modulating system. In this generator, the fractional-turn ratio saturable pulse transformer is the key component since it acts as a step-up transformer and a main switch during the working process. Demonstrative experiments show that if the primary storage capacitors are charged to 400 V, a quasi-square pulse with amplitude of about 29 kV can be achieved on a 3500 Ω resistive load, as well as the pulse duration (full width at half maximum) of about 1.3 μs. Preliminary repetition rate experiments are also carried out, which indicate that this pulse generator could work stably with the repetition rates of 30 Hz and 50 Hz. It can be concluded that this kind of all-solid-state microsecond-range quasi-square pulse generator can not only lower both the operating voltage of the primary windings and the saturable inductance of the secondary windings, thus ideally realizing the magnetic switch function of the fractional-turn ratio saturable pulse transformer, but also achieve a quasi-square pulse with high quality and fixed flat top after the modulation of a two-section anti-resonance network. This generator can be applied in areas of large power microwave sources, sterilization, disinfection, and wastewater treatment.

  2. 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...

  3. 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.

  4. 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

  5. Time-resolved measurements of charge carrier dynamics and optical nonlinearities in narrow-bandgap semiconductors

    Science.gov (United States)

    Olson, Benjamin Varberg

    generating excess carriers near one end of a MWIR T2SL and measuring the transit time to a thin, 2 lower-bandgap superlattice placed at the other end, the time-of-flight of vertically diffusing carriers is determined. Through investigation of both unintentionally doped and p-type superlattices at 77 K, the vertical hole and electron diffusion coefficients are determined to be 0.04+/-0.03 cm2/s and 4.7+/-0.5 cm2/s, corresponding to vertical mobilities of 6+/-5 cm 2/Vs and 700+/-80 cm2/Vs, respectively. These measurements are, to my knowledge, the first direct measurements of vertical transport properties in narrow-bandgap superlattices. Lastly, the widely tunable two-color ultrafast laser system used in this research allowed for the investigation of nonlinear optical properties in narrow-bandgap semiconductors. Time-resolved measurements taken at 77 K of the nondegenerate two-photon absorption spectrum of bulk n-type GaSb have provided new information about the nonresonant change in absorption and two-photon absorption coefficients in this material. Furthermore, as the nondegenerate spectrum was measured over a wide range of optical frequencies, a Kramers-Kronig transformation allowed the dispersion of the nondegenerate nonlinear refractive index to be calculated.

  6. 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.

  7. 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

  8. Type-II InP quantum dots in wide-bandgap InGaP host for intermediate-band solar cells

    Science.gov (United States)

    Tayagaki, Takeshi; Sugaya, Takeyoshi

    2016-04-01

    We demonstrate type-II quantum dots (QDs) with long carrier lifetimes in a wide-bandgap host as a promising candidate for intermediate-band solar cells. Type-II InP QDs are fabricated in a wide-bandgap InGaP host using molecular beam epitaxy. Time-resolved photoluminescence measurements reveal an extremely long carrier lifetime (i.e., greater than 30 ns). In addition, from temperature-dependent PL spectra, we find that the type-II InP QDs form a negligible valence band offset and conduction band offset of ΔEc ≈ 0.35 eV in the InGaP host. Such a type-II confinement potential for InP/InGaP QDs has a significant advantage for realizing efficient two-step photon absorption and suppressed carrier capture in QDs via Auger relaxation.

  9. Development of Lithium Stuffed Garnet-Type Oxide Solid Electrolytes with High Ionic Conductivity for Application to All-Solid-State Batteries

    Directory of Open Access Journals (Sweden)

    Ryoji Inada

    2016-07-01

    Full Text Available All-solid-state lithium-ion battery (LiB is expected as one of the next generation energy storage devices because of their high energy density, high safety and excellent cycle stability. Although oxide-based solid electrolyte materials have rather lower conductivity and poor deformability than sulfide-based one, they have other advantages such as their chemical stability and easiness for handling. Among the various oxide-based SEs, lithium stuffed garnet-type oxide with the formula of Li7La3Zr2O12 (LLZ have been widely studied because of their high conductivity above 10-4 Scm-1 at room temperature, excellent thermal performance and stability against Li metal anode.Here, we present our recent progress for the development of garnet-type solid electrolytes with high conductivity by simultaneous substitution of Ta5+ into Zr4+ site and Ba2+ into La3+ site in LLZ. Li+ concentration was fixed to 6.5 per chemical formulae, so that the formulae of our Li garnet-type oxide is expressed as Li6.5La3-xBaxZr1.5-xTa0.5+xO12 (LLBZT and Ba contents x are changed from 0 to 0.3. As results, all LLBZT samples have cubic garnet structure without containing any secondary phases. The lattice parameters of LLBZT decrease with increasing Ba2+ contents x < 0.10 while increase with x from 0.10 to 0.30, possibly due to the simultaneous change of Ba2+ and Ta5+ substitution levels. Relative densities of LLBZT are in the range between 89% and 93% and not influenced so much by the compositions. From AC impedance spectroscopy measurements, the total (bulk + grain conductivity at 27ºC of LLBZT shows its maximum value of 8.34 x 10-4 S cm-1 at x = 0.10, which is slightly higher than the conductivity (= 7.94 x 10-4 S cm-1 of LLZT without substituting Ba (x = 0. Activation energy of the conductivity tends to become lower by Ba substation, while excess Ba substitution degrades the conductivity in LLBZT. LLBZT has wide electrochemical potential window of 0-6 V vs. Li+/Li and

  10. Light confinement at a Dirac point in honeycomb-like lattice photonic crystal

    Science.gov (United States)

    Mao, Qiuping; Xie, Kang; Hu, Lei; Li, Qian; Zhang, Wei; Jiang, Haiming; Hu, Zhijia; Wang, Erlei

    2017-02-01

    Optical waveguides and cavities are important components among modern optical devices. Traditional optical cavities rely on total internal reflection or photonic bandgaps to achieve field confinement. Recently, a new type of trapped mode, the Dirac mode, has been reported to occur in triangular or honeycomb lattice photonic crystal. This novel localized mode is attribute to neither of the traditional light-guiding mechanisms and owns different characteristics. Here we report the discovery of the Dirac mode in honeycomb-like photonic crystal lattice. The Dirac mode occurs at a Dirac frequency, which is beyond the complete photonic bandgaps. It has a different algebraic-decay feature. Our discovery extends applicability of the Dirac mode in designing for optical devices.

  11. Amorphous Photonic Lattices: Band Gaps, Effective Mass and Suppressed Transport

    OpenAIRE

    Rechtsman, Mikael; Szameit, Alexander; Dreisow, Felix; Heinrich, Matthias; Keil, Robert; Nolte, Stefan; Segev, Mordechai

    2010-01-01

    We present, theoretically and experimentally, amorphous photonic lattices exhibiting a band-gap yet completely lacking Bragg diffraction: 2D waveguides distributed randomly according to a liquid-like model responsible for the absence of Bragg peaks as opposed to ordered lattices containing disorder, which always exhibit Bragg peaks. In amorphous lattices the bands are comprised of localized states, but we find that defect states residing in the gap are more localized than the Anderson localiz...

  12. Composition and bandgap-graded semiconductor alloy nanowires.

    Science.gov (United States)

    Zhuang, Xiujuan; Ning, C Z; Pan, Anlian

    2012-01-03

    Semiconductor alloy nanowires with spatially graded compositions (and bandgaps) provide a new material platform for many new multifunctional optoelectronic devices, such as broadly tunable lasers, multispectral photodetectors, broad-band light emitting diodes (LEDs) and high-efficiency solar cells. In this review, we will summarize the recent progress on composition graded semiconductor alloy nanowires with bandgaps graded in a wide range. Depending on different growth methods and material systems, two typical nanowire composition grading approaches will be presented in detail, including composition graded alloy nanowires along a single substrate and those along single nanowires. Furthermore, selected examples of applications of these composition graded semiconductor nanowires will be presented and discussed, including tunable nanolasers, multi-terminal on-nanowire photodetectors, full-spectrum solar cells, and white-light LEDs. Finally, we will make some concluding remarks with future perspectives including opportunities and challenges in this research area.

  13. Omnidirectional bandgaps in Fibonacci quasicrystals containing single-negative materials.

    Science.gov (United States)

    Deng, Xin-Hua; Liu, Jiang-Tao; Huang, Jie-Hui; Zou, Liner; Liu, Nian-Hua

    2010-02-10

    The band structure and bandgaps of one-dimensional Fibonacci quasicrystals composed of epsilon-negative materials and mu-negative materials are studied. We show that an omnidirectional bandgap (OBG) exists in the Fibonacci structure. In contrast to the Bragg gaps, such an OBG is insensitive to the incident angle and the polarization of light, and the width and location of the OBG cease to change with increasing Fibonacci order, but vary with the thickness ratio of both components, and the OBG closes when the thickness ratio is equal to the golden ratio. Moreover, the general formulations of the higher and lower band edges of the OBG are obtained by the effective medium theory. These results could lead to further applications of Fibonacci structures.

  14. Bandgap narrowing in moderately to heavily doped silicon

    Science.gov (United States)

    Lanyon, H. P. D.; Tuft, R. A.

    1979-01-01

    A theoretical model of bandgap narrowing in silicon at high doping levels has been developed. The model takes into account the electrostatic energy of interaction between a minority carrier and the majority carriers surrounding it, which reduces the thermal energy necessary for creation of an electron-hole pair. A pair energy similar to the excitonic binding energy of bound electron-hole pairs in insulators is obtained. Theoretical results are in excellent agreement with experimental results in the doping range from 3 times 10 to the 17th to 1.5 times 10 to the 20th/cu cm at room temperature. These results indicate that at high injection levels such as a transistor biased into the conductivity-modulation regime or a solar cell whose surface is established by ion implantation into an oxide layer, the bandgap narrowing is determined by the injected carrier concentration rather than by the doping level.

  15. Design techniques for superposition of acoustic bandgaps using fractal geometries

    CERN Document Server

    Castiñeira-Ibáñez, S; Sánchez-Pérez, J V; Garcia-Raffi, L M

    2010-01-01

    Research into properties of heterogeneous artificial materials, consisting of arrangements of rigid scatterers embedded in a medium with different elastic properties, has been intense throughout last two decades. The capability to prevent the transmission of waves in predetermined bands of frequencies -called bandgaps- becomes one of the most interesting properties of these systems, and leads to the possibility of designing devices to control wave propagation. The underlying physical mechanism is destructive Bragg interference. Here we show a technique that enables the creation of a wide bandgap in these materials, based on fractal geometries. We have focused our work in the acoustic case where these materials are called Phononic/Sonic Crystals (SC) but, the technique could be applied any types of crystals and wave types in ranges of frequencies where the physics of the process is linear.

  16. 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....

  17. Modal dynamics in hollow-core photonic-crystal fibers with elliptical veins.

    Science.gov (United States)

    Hochman, Amit; Leviatan, Yehuda

    2005-08-08

    Modal characteristics of hollow-core photonic-crystal fibers with elliptical veins are studied by use of a recently proposed numerical method. The dynamic behavior of bandgap guided modes, as the wavelength and aspect ratio are varied, is shown to include zero-crossings of the birefringence, polarization dependent radiation losses, and deformation of the fundamental mode.

  18. Mapping the broadband polarization properties of linear 2D SOI photonic crystal waveguides

    DEFF Research Database (Denmark)

    Canning, John; Skivesen, Nina; Kristensen, Martin;

    2007-01-01

    cut-off. We also observe relatively broadband mixing between the two eigenstates to generate a complete photonic bandgap. By careful analysis of the output polarisation state we report on an inherent non-reciprocity between quasi TE and TM fundamental mode cross coupling. The nature of polarisation...

  19. The Longwave Silicon Chip - Integrated Plasma-Photonics in Group IV And III-V Semiconductors

    Science.gov (United States)

    2013-10-01

    collaboration on theory: Walter Buchwald, UMass Boston; Justin Cleary, AFRL; Joshua Hendrickson, AFRL; Jacob Khurgin, Johns Hopkins; Zoran Ikonic , Univ... Ikonic , “The direct and indirect bandgaps of SixGe1-x-ySny and their photonic device applications” Journal of Applied Physics, vol. 112, 073106

  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.

  1. Enhanced cycling stability of NiCo2S4@NiO core-shell nanowire arrays for all-solid-state asymmetric supercapacitors.

    Science.gov (United States)

    Huang, Yuanyuan; Shi, Tielin; Jiang, Shulan; Cheng, Siyi; Tao, Xiangxu; Zhong, Yan; Liao, Guanglan; Tang, Zirong

    2016-12-07

    As a new class of pseudocapacitive material, metal sulfides possess high electrochemical performance. However, their cycling performance as conventional electrodes is rather poor for practical applications. In this article, we report an original composite electrode based on NiCo2S4@NiO core-shell nanowire arrays (NWAs) with enhanced cycling stability. This three-dimensional electrode also has a high specific capacitance of 12.2 F cm(-2) at the current density of 1 mA cm(-2) and excellent cycling stability (about 89% retention after 10,000 cycles). Moreover, an all-solid-state asymmetric supercapacitor (ASC) device has been assembled with NiCo2S4@NiO NWAs as the positive electrode and active carbon (AC) as the negative electrode, delivering a high energy density of 30.38 W h kg(-1) at 0.288 KW kg(-1) and good cycling stability (about 109% retention after 5000 cycles). The results show that NiCo2S4@NiO NWAs are promising for high-performance supercapacitors with stable cycling based on the unique core-shell structure and well-designed combinations.

  2. An electronic tongue using potentiometric all-solid-state PVC-membrane sensors for the simultaneous quantification of ammonium and potassium ions in water.

    Science.gov (United States)

    Gallardo, J; Alegret, S; Muñoz, R; De-Román, M; Leija, L; Hernández, P R; del Valle, M

    2003-09-01

    The simultaneous determination of NH(4)(+) and K(+) in solution has been attempted using a potentiometric sensor array and multivariate calibration. The sensors used are rather non-specific and of all-solid-state type, employing polymeric (PVC) membranes. The subsequent data processing is based on the use of a multilayer artificial neural network (ANN). This approach is given the name "electronic tongue" because it mimics the sense of taste in animals. The sensors incorporate, as recognition elements, neutral carriers belonging to the family of the ionophoric antibiotics. In this work the ANN type is optimized by studying its topology, the training algorithm, and the transfer functions. Also, different pretreatments of the starting data are evaluated. The chosen ANN is formed by 8 input neurons, 20 neurons in the hidden layer and 2 neurons in the output layer. The transfer function selected for the hidden layer was sigmoidal and linear for the output layer. It is also recommended to scale the starting data before training. A correct fit for the test data set is obtained when it is trained with the Bayesian regularization algorithm. The viability for the determination of ammonium and potassium ions in synthetic samples was evaluated; cumulative prediction errors of approximately 1% (relative values) were obtained. These results were comparable with those obtained with a generalized regression ANN as a reference algorithm. In a final application, results close to the expected values were obtained for the two considered ions, with concentrations between 0 and 40 mmol L(-1).

  3. 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.

  4. Characteristics of rapid-thermal-annealed LiCoO2 cathode film for an all-solid-state thin film microbattery

    Science.gov (United States)

    Kim, Han-Ki; Yoon, Young Soo

    2004-07-01

    We report on the fabrication of a LiCoO2 film for an all-solid-state thin film microbattery by using a rapid-thermal-annealing (RTA) process. The LiCoO2 films were grown by rf magnetron sputtering using a synthesized LiCoO2 target in a [O2/(Ar+O2)] ratio of 10%. Scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) analysis results showed that the surface layer on the as-deposited LiCoO2 film was completely removed by rapid thermal annealing process in oxygen ambient for 20 min. In addition, the thin film microbattery fabricated with the annealed LiCoO2 film shows fairly stable cyclability with a specific discharge capacity of 56.49 μAh/cm2 μm. These results show the possibility of the RTA LiCoO2 film and rapid thermal annealing process being a promising cathode material and annealing process for thin film microbatteries, respectively. .

  5. All-solid-state supercapacitors with poly(3,4-ethylenedioxythiophene)-coated carbon fiber paper electrodes and ionic liquid gel polymer electrolyte

    Science.gov (United States)

    Pandey, G. P.; Rastogi, A. C.; Westgate, Charles R.

    2014-01-01

    All-solid-state thin supercapacitors have been fabricated using current pulse polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) over carbon fiber paper and ionic liquid based gel polymer electrolyte. The PEDOT-coated carbon paper electrodes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) which confirm the porous morphology of PEDOT at the nanoscale and a high degree of ClO4- dopant ion conjugation. The performance characteristics of the supercapacitor cells have been evaluated by ac impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge techniques. The PEDOT electrode shows specific capacitance of ∼154.5 F g-1, which correspond to the cell area-normalized capacitance of 85 mF cm-2. The maximum specific energy and specific power of the solid-state supercapacitor cell, calculated from charge-discharge characteristics, are 6.5 Wh kg-1 and 11.3 kW kg-1, respectively. The solid-state supercapacitor shows good cycle durability and time stability. The thin, lightweight, gel electrolyte based supercapacitor shows considerable potential for low-cost, high-performance energy storage applications.

  6. 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...

  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.

  8. High-energy-density, all-solid-state microsupercapacitors with three-dimensional interdigital electrodes of carbon/polymer electrolyte composite

    Science.gov (United States)

    Pu, Juan; Wang, Xiaohong; Zhang, Tianyi; Li, Siwei; Liu, Jinghe; Komvopoulos, Kyriakos

    2016-01-01

    Novel all-solid-state microsupercapacitors (MSCs) with three-dimensional (3D) electrodes consisting of active materials (i.e., graphene or activated carbon (AC) particles) and polymer electrolyte (PE) designed for high-energy-density storage applications were fabricated and tested in this work. The incorporation of PE in the electrode material enhances the accessibility of electrolyte ions to the surface of active materials and decreases the ion diffusion path during electrochemical charge/discharge. For a scan rate of 5 mV s-1, the MSCs with graphene/PE and AC/PE composite electrodes demonstrate a very high areal capacitance of 95 and 134 mF cm-2, respectively, comparable to that of 3D MSCs with liquid electrolyte. In addition, the graphene/PE MSCs show a ˜70% increase in specific capacitance after 10 000 charge/discharge cycles, attributed to an electro-activation process resulting from ion intercalation between the graphene nanosheets. The AC/PE MSCs also demonstrate excellent stability. The results of this study illustrate the potential of the present 3D MSCs for various high-density solid-state energy storage applications.

  9. 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.

  10. Enhanced cycling stability of NiCo2S4@NiO core-shell nanowire arrays for all-solid-state asymmetric supercapacitors

    Science.gov (United States)

    Huang, Yuanyuan; Shi, Tielin; Jiang, Shulan; Cheng, Siyi; Tao, Xiangxu; Zhong, Yan; Liao, Guanglan; Tang, Zirong

    2016-12-01

    As a new class of pseudocapacitive material, metal sulfides possess high electrochemical performance. However, their cycling performance as conventional electrodes is rather poor for practical applications. In this article, we report an original composite electrode based on NiCo2S4@NiO core-shell nanowire arrays (NWAs) with enhanced cycling stability. This three-dimensional electrode also has a high specific capacitance of 12.2 F cm-2 at the current density of 1 mA cm-2 and excellent cycling stability (about 89% retention after 10,000 cycles). Moreover, an all-solid-state asymmetric supercapacitor (ASC) device has been assembled with NiCo2S4@NiO NWAs as the positive electrode and active carbon (AC) as the negative electrode, delivering a high energy density of 30.38 W h kg-1 at 0.288 KW kg-1 and good cycling stability (about 109% retention after 5000 cycles). The results show that NiCo2S4@NiO NWAs are promising for high-performance supercapacitors with stable cycling based on the unique core-shell structure and well-designed combinations.

  11. 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.

  12. Comparative Study of PVC-Free All-Solid-State, PVC Membrane, and Carbon Paste Ion-Selective Electrodes for the Determination of Dapoxetine Hydrochloride in Pharmaceutical Formulation.

    Science.gov (United States)

    Aziz, Azza; Khamees, Nesrin; Mohamed, Tagreed Abdel-Fattah; Derar, Abeer Rashad

    2016-11-01

    The potentiometric response characteristics and analytical applications of a poly(vinyl chloride) (PVC)-free all-solid-state ion-selective electrode for dapoxetine hydrochloride (DAP) are examined. The Nernstian response of the electrode was evaluated by comparison with PVC-based liquid membrane and carbon paste electrodes. The PVC-free electrode is prepared by direct incorporation of dapoxetine-tetraphenyl borate (DAP-TPB) as a sensing element into a commercial nail varnish containing cellulose acetate propionate. The composite was applied onto a 3 mm diameter graphite disk electrode. The electrode exhibited a Nernstian slope of 56.0 mV/decade in the concentration range of 1 × 10-4 to 1 × 10-2 mol/L with an LOD of 2 × 10-5 mol/L. The electrode is independent of pH in the range of 2 to 6 and showed good selectivity for DAP with respect to a large number of inorganic cations and amino acids. Comparable Nernstian slope, sensitivity, pH range, and selectivity pattern were obtained with a PVC membrane and a carbon paste incorporating DAP-TPB as a sensing element and dioctylphthalate as a solvent mediator. The electrodes were used for the determination of DAP in pure solution and in tablets without extraction with high accuracy and precision (RSD ≤ 2%). The nail varnish solid-state electrode is simple, economical, and rapid when compared with PVC membrane and carbon paste electrodes.

  13. 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.

  14. 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.

  15. 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.

  16. Defect-induced bandgap narrowing in low-k dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.; Zheng, H.; Shohet, J. L. [Plasma Processing & Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); King, S. W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States); Afanas' ev, V. V. [Department of Physics, University of Leuven, B-3001 Leuven (Belgium); Baklanov, M. R.; Marneffe, J.-F. de [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Nishi, Y. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-08-24

    In this work, core-level X-ray photoelectron spectroscopy was utilized to determine the surface bandgap for various porous and non-porous low-k a-SiCOH dielectrics before and after ion sputtering. By examining the onset of inelastic energy loss in O 1s core-level spectra, the gap narrowing was universally found in Ar{sup +} ion sputtered low-k dielectrics. The reduction of the bandgap ranges from 1.3 to 2.2 eV depending on the film composition. We show that the bandgap narrowing in these low-k dielectrics is caused by development of the valence-band tail as evidenced by the presence of additional electronic states above the valence-band maximum. Electron-spin-resonance measurements were made on a-SiCOH films to gain atomic insight into the nature of the sputtering-induced defects and reveal formation of carbon-related defects as the most probable origin of the gap states.

  17. Bandgap modulation of carbon nanotubes by encapsulated metallofullerenes

    Science.gov (United States)

    Lee, Jhinhwan; Kim, H.; Kahng, S.-J.; Kim, G.; Son, Y.-W.; Ihm, J.; Kato, H.; Wang, Z. W.; Okazaki, T.; Shinohara, H.; Kuk, Young

    2002-02-01

    Motivated by the technical and economic difficulties in further miniaturizing silicon-based transistors with the present fabrication technologies, there is a strong effort to develop alternative electronic devices, based, for example, on single molecules. Recently, carbon nanotubes have been successfully used for nanometre-sized devices such as diodes, transistors, and random access memory cells. Such nanotube devices are usually very long compared to silicon-based transistors. Here we report a method for dividing a semiconductor nanotube into multiple quantum dots with lengths of about 10nm by inserting Gd@C82 endohedral fullerenes. The spatial modulation of the nanotube electronic bandgap is observed with a low-temperature scanning tunnelling microscope. We find that a bandgap of ~0.5eV is narrowed down to ~0.1eV at sites where endohedral metallofullerenes are inserted. This change in bandgap can be explained by local elastic strain and charge transfer at metallofullerene sites. This technique for fabricating an array of quantum dots could be used for nano-electronics and nano-optoelectronics.

  18. High PSRR bandgap reference used in boost circuit

    Science.gov (United States)

    Li, Yi; Duan, Baoxing; Wang, Yong; Yang, Yintang

    2017-03-01

    Based on pre-regulated voltage structure, a voltage bandgap reference with high power supply rejection ratio (PSRR) is presented in this paper. A pre-regulated voltage structure is used in the circuit to achieve isolating the supply voltage of the bandgap core circuit from VDD to reach a high PSRR. The circuit was designed and simulated in 0.35um BCD technology. The results show the output voltage variation versus temperature (-50°C -100°C) is 8.8 ppm/°C, bandgap reference voltage is 1.236V, current consumption is 30.3 µA. Noise is 53.54 µV/Hz-1/2 at 1Hz. PSRR is -91dB at low frequency, -90.3dB at 1 kHz and -30.3dB at 1MHz. thus, the circuit maintains a good performance in PSRR through a broad frequency.

  19. Photon technology. Hard photon technology; Photon technology. Hard photon gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    For the application of photon to industrial technologies, in particular, a hard photon technology was surveyed which uses photon beams of 0.1-200nm in wavelength. Its features such as selective atom reaction, dense inner shell excitation and spacial high resolution by quantum energy are expected to provide innovative techniques for various field such as fine machining, material synthesis and advanced inspection technology. This wavelength region has been hardly utilized for industrial fields because of poor development of suitable photon sources and optical devices. The developmental meaning, usable time and issue of a hard photon reduction lithography were surveyed as lithography in ultra-fine region below 0.1{mu}m. On hard photon analysis/evaluation technology, the industrial use of analysis, measurement and evaluation technologies by micro-beam was viewed, and optimum photon sources and optical systems were surveyed. Prediction of surface and surface layer modification by inner shell excitation, the future trend of this process and development of a vacuum ultraviolet light source were also surveyed. 383 refs., 153 figs., 17 tabs.

  20. 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.

  1. Selective-fluid-filled photonic crystal fibers and applications

    Science.gov (United States)

    Wang, Yiping; Liao, Changrui; Zhong, Xiaoyong; Li, Zhengyong; Liu, Yingjie; Zhou, Jiangtao; Yang, Kaiming

    2013-08-01

    A selective-filling technique was demonstrated to improve the optical properties of photonic crystal fibres (PCFs). Such a technique can be used to fill one or more fluid samples selectively into desired air holes. The technique is based on drilling a hole or carving a groove on the surface of a PCF to expose selected air holes to atmosphere by the use of a micromachining system comprising of a femtosecond infrared laser and a microscope. The exposed section was immersed into a fluid and the air holes are then filled through the well-known capillarity action. Provided two or more grooves are fabricated on different locations and different orientation along the fibre surface, different fluids may be filled into different airholes to form a hybrid fibre. As an example, we filled half of a pure-silica PCF by a fluid with n=1.480 by carving a rectangular groove on the fibre. Consequently, the half-filled PCF became a bandgap-guiding structure (upper half), resulted from a higher refractive index in the fluid rods than in the fibre core, and three bandgaps were observed within the wavelength range from 600 to 1700 nm. Whereas, the lower half (unfilled holes) of the fibre remains an air/silica index-guiding structure. When the hybrid PCF is bent, its bandgaps gradually narrowed, resulted from the shifts of the bandgap edges. The bandgap edges had distinct bend-sensitivities when the hybrid PCF was bent toward different directions. Especially, the bandgaps are hardly affected when the half-filled PCF was bent toward the fluid-filled region. Such unique bend properties could be used to monitor simultaneously the bend directions and the curvature of the engineering structures.

  2. Photonic crystal digital alloys and their band structure properties.

    Science.gov (United States)

    Lee, Jeongkug; Kim, Dong-Uk; Jeon, Heonsu

    2011-09-26

    We investigated semi-disordered photonic crystals (PCs), digital alloys, and made thorough comparisons with their counterparts, random alloys. A set of diamond lattice PC digital alloys operating in a microwave regime were prepared by alternately stacking two kinds of sub-PC systems composed of alumina and silica spheres of the same size. Measured transmission spectra as well as calculated band structures revealed that when the digital alloy period is short, band-gaps of the digital alloys are practically the same as those of the random alloys. This study indicates that the concept of digital alloys holds for photons in PCs as well.

  3. 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.)

  4. Photon generator

    Science.gov (United States)

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  5. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2013-01-01

    Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-freq

  6. An electronic tongue using potentiometric all-solid-state PVC-membrane sensors for the simultaneous quantification of ammonium and potassium ions in water

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, J.; Alegret, S.; del Valle, M. [Sensors and Biosensors Group, Department of Chemistry, Autonomous University of Barcelona, Edifici Cn, 08193, Bellaterra, Catalonia (Spain); Munoz, R.; De-Roman, M.; Leija, L.; Hernandez, P.R. [Bioelectronics Section, Department of Electrical Engineering, CINVESTAV, Mexico DF (Mexico)

    2003-09-01

    The simultaneous determination of NH{sub 4}{sup +} and K{sup +} in solution has been attempted using a potentiometric sensor array and multivariate calibration. The sensors used are rather non-specific and of all-solid-state type, employing polymeric (PVC) membranes. The subsequent data processing is based on the use of a multilayer artificial neural network (ANN). This approach is given the name ''electronic tongue'' because it mimics the sense of taste in animals. The sensors incorporate, as recognition elements, neutral carriers belonging to the family of the ionophoric antibiotics. In this work the ANN type is optimized by studying its topology, the training algorithm, and the transfer functions. Also, different pretreatments of the starting data are evaluated. The chosen ANN is formed by 8 input neurons, 20 neurons in the hidden layer and 2 neurons in the output layer. The transfer function selected for the hidden layer was sigmoidal and linear for the output layer. It is also recommended to scale the starting data before training. A correct fit for the test data set is obtained when it is trained with the Bayesian regularization algorithm. The viability for the determination of ammonium and potassium ions in synthetic samples was evaluated; cumulative prediction errors of approximately 1% (relative values) were obtained. These results were comparable with those obtained with a generalized regression ANN as a reference algorithm. In a final application, results close to the expected values were obtained for the two considered ions, with concentrations between 0 and 40 mmol L{sup -1}. (orig.)

  7. 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.

  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. Tamm-plasmon and surface-plasmon hybrid-mode based refractometry in photonic bandgap structures.

    Science.gov (United States)

    Das, Ritwick; Srivastava, Triranjita; Jha, Rajan

    2014-02-15

    The transverse magnetic (TM) polarized hybrid modes formed as a consequence of coupling between Tamm plasmon polariton (TM-TPP) mode and surface plasmon polariton (SPP) mode exhibit interesting dispersive features for realizing a highly sensitive and accurate surface plasmon resonance (SPR) sensor. We found that the TM-TPP modes, formed at the interface of distributed Bragg reflector and metal, are strongly dispersive as compared to SPP modes at optical frequencies. This causes an appreciably narrow interaction bandwidth between TM-TPP and SPP modes, which leads to highly accurate sensing. In addition, appropriate tailoring of dispersion characteristics of TM-TPP as well as SPP modes could ensure high sensitivity of a novel SPR platform. By suitably designing the Au/TiO₂/SiO₂-based geometry, we propose a TM-TPP/SPP hybrid-mode sensor and achieve a sensitivity ≥900  nm/RIU with high detection accuracy (≥30  μm⁻¹) for analyte refractive indices varying between 1.330 and 1.345 in 600-700 nm wavelength range. The possibility to achieve desired dispersive behavior in any spectral band makes the sensing configuration an extremely attractive candidate to design sensors depending on the availability of optical sources.

  10. Very-large-mode-area photonic bandgap Bragg fiber polarizing in a wide spectral range.

    Science.gov (United States)

    Aleshkina, Svetlana S; Likhachev, Mikhail E; Pryamikov, Andrey D; Gaponov, Dmitry A; Denisov, Alexandr N; Bubnov, Mikhail M; Salganskii, Mikhail Yu; Laptev, Alexandr Yu; Guryanov, Aleksei N; Uspenskii, Yurii A; Popov, Nikolay L; Février, Sébastien

    2011-09-15

    A design of a polarizing all-glass Bragg fiber with a microstructure core has been proposed for the first time. This design provides suppression of high-order modes and of one of the polarization states of the fundamental mode. The polarizing fiber was fabricated by a new, simple method based on a combination of the modified chemical vapor deposition (MCVD) process and the rod-in-tube technique. The mode field area has been found to be about 870 μm² near λ=1064 nm. The polarization extinction ratio better than 13 dB has been observed over a 33% wavelength range (from 1 to 1.4 μm) after propagation in a 1.7 m fiber piece bent to a radius of 70 cm.

  11. 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.

  12. Local resonance and Bragg bandgaps in sandwich beams containing periodically inserted resonators

    CERN Document Server

    Sharma, Bhisham

    2015-01-01

    We study the low frequency wave propagation behavior of sandwich beams containing periodically embedded internal resonators. A closed form expression for the propagation constant is obtained using a phased array approach and verified using finite element simulations. We show that local resonance and Bragg bandgaps coexist in such a system and that the width of both bandgaps is a function of resonator parameters as well as their periodicity. The interaction between the two bandgaps is studied by varying the local resonance frequency. We find that a single combined bandgap does not exist for this system and that the Bragg bandgaps transition into sub-wavelength bandgaps when the local resonance frequency is above their associated classical Bragg frequency.

  13. 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.

  14. 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.

  15. Limits of slow light in photonic crystals

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Xiao, Sanshui; Mortensen, N. Asger

    2008-01-01

    in the group velocity acquiring a finite value above zero at the band-gap edges while attaining uperluminal values within the band gap. Simple scalings of the minimum and maximum group velocities with the imaginary part of the dielectric function or, equivalently, the linewidth of the broadened states......While ideal photonic crystals would support modes with a vanishing group velocity, state-of-the-art structures have still only provided a slow down by roughly two orders of magnitude. We find that the induced density of states caused by lifetime broadening of the electromagnetic modes results...... are presented. The results obtained are entirely general and may be applied to any effect which results in a broadening of the electromagnetic states, such as loss, disorder, and finite-size effects. This significantly limits the reduction in group velocity attainable via photonic crystals....

  16. 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.

  17. A Nanomembrane-Based Bandgap-Tunable Germanium Microdisk Using Lithographically-Customizable Biaxial Strain for Silicon-Compatible Optoelectronics

    CERN Document Server

    Sukhdeo, David S; Kang, Ju-Hyung; Brongersma, Mark L; Saraswat, Krishna C

    2014-01-01

    Strain engineering has proven to be vital for germanium-based photonics, in particular light emission. However, applying a large permanent biaxial strain to germanium has been a challenge. We present a simple, CMOS-compatible technique to conveniently induce a large, spatially homogenous strain in microdisks patterned within ultrathin germanium nanomembranes. Our technique works by concentrating and amplifying a pre-existing small strain into the microdisk region. Biaxial strains as large as 1.11% are observed by Raman spectroscopy and are further confirmed by photoluminescence measurements, which show enhanced and redshifted light emission from the strained microdisks. Our technique allows the amount of biaxial strain to be customized lithographically, allowing the bandgaps of different microdisks to be independently tuned in a single mask process. Our theoretical calculations show that this platform can deliver substantial performance improvements, including a >200x reduction in the lasing threshold, to bia...

  18. Photonic crystal waveguides based on wide-gap semiconductor alloys

    Science.gov (United States)

    Martin, Aude; Combrié, Sylvain; De Rossi, Alfredo

    2017-03-01

    This review is devoted to integrated photonic platforms based on large band-gap semiconductors, alternatives to silicon photonics. The large electronic band gap of the material employed is chosen to address the specific needs of nonlinear optics, and, in particular, lower nonlinear losses and the capability of handling larger optical power densities. Moreover, these new platforms offer broader transmission spectra, extending to the visible spectral region, which is also required for other applications, particularly sensing and bio-related photonics. The focus is on nanoscale patterned waveguiding structures, which, owing to the tight confinement of light, have demonstrated a large nonlinear response. The third-order nonlinear response and the related parametric interactions will be considered here, encompassing four-wave mixing, phase-sensitive amplification, wavelength conversion, and also nonlinear pulse propagation and soliton dynamics. The comparison between different materials and waveguide design highlights specific features of photonic crystal waveguides.

  19. Photonic crystal enhancement of auger-suppressed infrared photodetectors

    Science.gov (United States)

    Djurić, Zoran; Jakšić, Zoran; Ehrfeld, Wolfgang; Schmidt, Andreas; Matić, Milan; Popović, Mirjana

    2001-04-01

    We examine theoretically and experimentally the possibilities to reach room-temperature background-limited operation of narrow-bandgap compound semiconductor photodetectors in (3-14) micrometer infrared wavelength range. To this purpose we consider the combination of non-equilibrium Auger suppression with photonic crystal enhancement (PCE). This means that Auger generation-recombination processes are suppressed utilizing exclusion, extraction or magnetoconcentration effects or their combination. The residual radiative recombination is removed by immersing the detector active area into a photonic crystal and using the benefits of re-absorption (photon recycling) to effectively increase the radiative lifetime. In this manner the total generation-recombination noise is strongly quenched in sufficiently defect-free device materials. It is concluded that the operation of thus enhanced photonic detectors could even approach signal fluctuation limit.

  20. 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.

  1. 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.

  2. Theoretical optimization and parametric study of n-on-p Al/x/Ga/1-x/As-GaAs graded band-gap solar cell

    Science.gov (United States)

    Hutchby, J. A.; Fudurich, R. L.

    1976-01-01

    A comprehensive theoretical model of the graded band-gap Al(x)Ga(1-x)As-GaAs solar cell is used to optimize the n-on-p cell. The model includes power losses due to surface, bulk, and junction minority-carrier recombination, series resistance, and photon reflection from an SiO antireflection coating of optimum thickness. The optimized cell has a junction depth/graded band-gap layer thickness of 1.0 micron, respective donor and acceptor concentrations of 4 x 10 to the 17th power and 2 x 10 to the 17th power per cu cm, and a surface AlAs mode fraction of x = 0.35. The optimized graded band-gap cell has an air-mass-zero efficiency of 17.7% (not corrected for a 13% front surface contact area) and is shown to be less sensitive than a similar n-on-p GaAs cell to material degradation in the form of decreased minority-carrier diffusion lengths and increased surface-recombination velocity

  3. Exploring Direct to Indirect Bandgap Transition in Silicon Nanowires: Size Effect

    Science.gov (United States)

    Shi, Lihong; Zhang, Gang

    2016-10-01

    We have investigated the electronic band structure of [110] silicon nanowires (SiNWs) using first-principles calculations. We find that, in the ultrathin diameter regime, SiNWs have a direct bandgap, but the energy difference between the indirect and direct fundamental bandgaps decreases as the nanowire diameter increases. This indicates that larger [110] SiNWs could have an indirect bandgap. Fundamentally, a series of quantitative direct-indirect bandgap transitional diameters are obtained for different cross-sectional geometries, with the largest values for SiNWs with triangular cross section.

  4. Urbach's rule derived from thermal fluctuations in the band-gap energy

    DEFF Research Database (Denmark)

    Skettrup, Torben

    1978-01-01

    The exponential absorption edge (known as Urbach's rule) observed in most materials is interpreted in terms of thermal fluctuations in the band-gap energy. The main contribution to the temperature shift of the band-gap energy is due to the temperature-dependent self-energies of the electrons...... and holes interacting with the phonons. Since the phonon number is fluctuating in thermal equilibrium, the band-gap energy is also fluctuating resulting in an exponential absorption tail below the average band-gap energy. These simple considerations are applied to derive Urbach's rule at high temperatures...

  5. Electrospun fibrous electrodes with tunable microstructure made of polyaniline/multi-walled carbon nanotube suspension for all-solid-state supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Junsheng; Su, Shijie; Fang, Xu [Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116023 (China); Wang, Dazhi, E-mail: d.wang@dlut.edu.cn [Key Laboratory for Micro/Nano Technology and System of Liaoning Province, Dalian University of Technology, Dalian 116023 (China); Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116023 (China); Xu, Shuangchao [Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116023 (China)

    2016-09-15

    Highlights: • Electrospun PANI/MWCNT fibrous electrodes for supercapacitor were prepared. • Microstructure of electrodes is tunable by changing the electrospin parameters. • Fiber-diameter dependence of the electrode performance was observed. • High performance and good stability of electrospun electrodes were obtained. - Abstract: Electrospinning technique was used to prepare high performance fibrous electrodes with tunable microstructure for all-solid-state electrochemical supercapacitor. Symmetrically sandwiched supercapacitors consisting of flexible electrospun polyaniline (PANI)/multi-walled carbon nanotube (MWCNT) electrodes and polyvinyl alcohol (PVA)/sulfuric acid (H{sub 2}SO{sub 4}) gel electrolyte were assembled. Tunable microstructure of the fibrous electrode was obtained by changing the electrospinning parameters including the collector–needle distance (CND) and the suspension flow rate (SFR). Results show that, higher CND combining with lower SFR can result in a smaller average diameter of the electrospun fibers and hence improve the electrode performance. When the CND changes from 80 to 140 mm, the average fiber diameter will decrease from 2.89 to 1.21 μm, and the specific surface area of the electrode can increase from 57 to 83 m{sup 2}·g{sup −1}. The corresponding specific capacitance of the electrospun electrode will therefore increase from 129.5 to 180 F·g{sup −1}, leading to a synchronous improvement of the energy density of the supercapacitor from 18 to 25 Wh·kg{sup −1}. On the other hand, the supercapacitors using fibrous electrodes in this work also show good rate capability and cycling stability. Using the electrode with an average fiber diameter of 1.21 μm, the specific capacitances can maintain 131 F·g{sup −1} at a current density of 4 A·g{sup −1}, which is 73% of the specific capacitance of the same sample at a current density of 0.5 A·g{sup −1}. And the specific capacitance of the electrode can retain 89

  6. Optoelectronic devices based on graded bandgap structures utilising electroplated semiconductors

    OpenAIRE

    2016-01-01

    The main aim of the work presented in this thesis is to develop low-cost multi-junction graded bandgap solar cells using electroplated semiconductors. The semiconductor materials explored in this research are CdSe, ZnTe, CdS, CdMnTe and CdTe thin films. These layers were characterised for their structural, compositional, morphological, optical, and electrical features using XRD, Raman spectroscopy, EDX, SEM, UV-Vis spectroscopy, PEC cell, C-V, I-V and UPS measurement techniques respectively. ...

  7. Surface band-gap narrowing in quantized electron accumulation layers.

    Science.gov (United States)

    King, P D C; Veal, T D; McConville, C F; Zúñiga-Pérez, J; Muñoz-Sanjosé, V; Hopkinson, M; Rienks, E D L; Jensen, M Fuglsang; Hofmann, Ph

    2010-06-25

    An energy gap between the valence and the conduction band is the defining property of a semiconductor, and the gap size plays a crucial role in the design of semiconductor devices. We show that the presence of a two-dimensional electron gas near to the surface of a semiconductor can significantly alter the size of its band gap through many-body effects caused by its high electron density, resulting in a surface band gap that is much smaller than that in the bulk. Apart from reconciling a number of disparate previous experimental findings, the results suggest an entirely new route to spatially inhomogeneous band-gap engineering.

  8. High bandgap III-V alloys for high efficiency optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

    2017-01-10

    High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

  9. 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....

  10. 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.

  11. Electrodeposited polyethylenedioxythiophene with infiltrated gel electrolyte interface: a close contest of an all-solid-state supercapacitor with its liquid-state counterpart

    Science.gov (United States)

    Anothumakkool, Bihag; Torris A. T, Arun; Bhange, Siddheshwar N.; Badiger, Manohar V.; Kurungot, Sreekumar

    2014-05-01

    We report the design of an all-solid-state supercapacitor, which has charge storage characteristics closely matching that of its liquid-state counterpart even under extreme temperature and humidity conditions. The prototype is made by electro-depositing polyethylenedioxythiophene (PEDOT) onto the individual carbon fibers of a porous carbon substrate followed by intercalating the matrix with polyvinyl alcohol-sulphuric acid (PVA-H2SO4) gel electrolyte. The electrodeposited layer of PEDOT maintained a flower-like growth pattern along the threads of each carbon fiber. This morphology and the alignment of PEDOT led to an enhanced surface area and electrical conductivity, and the pores in the system enabled effective intercalation of the polymer-gel electrolyte. Thus, the established electrode-electrolyte interface nearly mimics that of its counterpart based on the liquid electrolyte. Consequently, the solid device attained very low internal resistance (1.1 Ω cm-2) and a high specific capacitance (181 F g-1) for PEDOT at a discharge current density of 0.5 A g-1. Even with a high areal capacitance of 836 mF cm-2 and volumetric capacitance of 28 F cm-3, the solid device retained a mass-specific capacitance of 111 F g-1 for PEDOT. This is in close agreement with the value displayed by the corresponding liquid-state system (112 F g-1), which was fabricated by replacing the gel electrolyte with 0.5 M H2SO4. The device also showed excellent charge-discharge stability for 12 000 cycles at 5 A g-1. The performance of the device was consistent even under wide-ranging humidity (30-80%) and temperature (-10 to 80 °C) conditions. Finally, a device fabricated by increasing the electrode area four times was used to light an LED, which validated the scalability of the process.We report the design of an all-solid-state supercapacitor, which has charge storage characteristics closely matching that of its liquid-state counterpart even under extreme temperature and humidity conditions

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Decay dynamics of quantum dots influenced by the local density of optical states of two-dimensional photonic crystal membranes

    DEFF Research Database (Denmark)

    Julsgaard, Brian; Johansen, Jeppe; Stobbe, Søren

    2008-01-01

    We have performed time-resolved spectroscopy on InAs quantum dot ensembles in photonic crystal membranes. The influence of the photonic crystal is investigated by varying the lattice constant systematically. We observe a strong slow down of the quantum dots’ spontaneous emission rates as the two-...... the bandgap in good agreement with local density of states calculations.......We have performed time-resolved spectroscopy on InAs quantum dot ensembles in photonic crystal membranes. The influence of the photonic crystal is investigated by varying the lattice constant systematically. We observe a strong slow down of the quantum dots’ spontaneous emission rates as the two...

  18. 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...

  19. Development of All-Solid-State Sensors for Measurement of Nitric Oxide and Ammonia Concentrations by Optical Absorption in Particle-Laden Combustion Exhaust Streams

    Energy Technology Data Exchange (ETDEWEB)

    Jerald A. Caton; Kalyan Annamalai; Robert P. Lucht

    2006-12-31

    An all-solid-state continuous-wave (cw) laser system for ultraviolet absorption measurements of the nitric oxide (NO) molecule has been developed and demonstrated. For the NO sensor, 250 nW of tunable cw ultraviolet radiation is produced by sum-frequency-mixing of 532-nm radiation from a diode-pumped Nd:YAG laser and tunable 395-nm radiation from an external cavity diode laser (ECDL). The sum-frequency-mixing process occurs in a beta-barium borate crystal. The nitric oxide absorption measurements are performed by tuning the ECDL and scanning the sum-frequency-mixed radiation over strong nitric oxide absorption lines near 226 nm. In Year 1 of the research, the nitric oxide sensor was used for measurements in the exhaust of a coal-fired laboratory combustion facility. The Texas A&M University boiler burner facility is a 30 kW (100,000 Btu/hr) downward-fired furnace with a steel shell encasing ceramic insulation. Measurements of nitric oxide concentration in the exhaust stream were performed after modification of the facility for laser based NOx diagnostics. The diode-laser-based ultraviolet absorption measurements were successful even when the beam was severely attenuated by particulate in the exhaust stream and window fouling. Single-laser-sweep measurements were demonstrated with an effective time resolution of 100 msec, limited at this time by the scan rate of our mechanically tuned ECDL system. In Year 2, the Toptica ECDL in the original system was replaced with a Sacher Lasers ECDL. The mode-hop-free tuning range and tuning rate of the Toptica ECDL were 25 GHz and a few Hz, respectively. The mode-hop-free tuning range and tuning rate of the Sacher Lasers ECDL were 90 GHz and a few hundred Hz, respectively. The Sacher Lasers ECDL thus allows us to scan over the entire NO absorption line and to determine the absorption baseline with increased accuracy and precision. The increased tuning rate is an advantage in that data can be acquired much more rapidly and the

  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.