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Sample records for electrically tunable liquid

  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 all...

  2. 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...

  3. Optimization of electrically tunable VCSEL with intracavity nematic liquid crystal.

    Science.gov (United States)

    Belmonte, Carlos; Frasunkiewicz, Leszek; Czyszanowski, Tomasz; Thienpont, Hugo; Beeckman, Jeroen; Neyts, Kristiaan; Panajotov, Krassimir

    2015-06-15

    We optimize the wavelength tuning range of a Vertical-Cavity Surface-Emitting Laser with an intracavity layer of nematic Liquid Crystal (LC-VCSEL) lasing around 1.3 μm. The tunability is obtained by applying voltage to the liquid crystal layer, which esentially is to vary the refractive index from the extraordinary to the ordinary. We achieve 71.6 nm continuous tuning (without mode hopping) with liquid crystal thickness of about 3.2 μm. We investigate the impact of ambient temperature on the LC-VCSEL tuning range and show that mode-hop tuning can be achieved in the temperature range from -10°C to 50°C where the LC is in nematic phase.

  4. Electrically tunable bandpass filter using solid-core photonic crystal fibers filled with multiple liquid crystals

    DEFF Research Database (Denmark)

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

    2010-01-01

    An electrically tunable bandpass filter is designed and fabricated by integrating two solid-core photonic crystal fibers filled with different liquid crystals in a double silicon v-groove assembly. By separately controlling the driving voltage of each liquid-crystal-filled section, both the short......-wavelength edge and the long-wavelength edge of the bandpass filter are tuned individually or simultaneously with the response time in the millisecond range....

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

    Science.gov (United States)

    Olausson, Christina B; Scolari, Lara; Wei, Lei; Noordegraaf, Danny; Weirich, Johannes; Alkeskjold, Thomas T; Hansen, Kim P; Bjarklev, Anders

    2010-04-12

    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 an all-spliced laser cavity based on the liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065 nm by applying an electric field to the silicon assembly.

  6. An Electrically Tunable Zoom System Using Liquid Lenses.

    Science.gov (United States)

    Li, Heng; Cheng, Xuemin; Hao, Qun

    2015-12-31

    A four-group stabilized zoom system using two liquid lenses and two fixed lens groups is proposed. We describe the design principle, realization, and the testing of a 5.06:1 zoom system. The realized effective focal length (EFL) range is 6.93 mm to 35.06 mm, and the field of view (FOV) range is 8° to 40°. The system can zoom fast when liquid lens 1's (L₁'s) optical power take the value from 0.0087 mm(-1) to 0.0192 mm(-1) and liquid lens 2's (L₂'s) optical power take the value from 0.0185 mm(-1) to -0.01 mm(-1). Response time of the realized zoom system was less than 2.5 ms, and the settling time was less than 15 ms.The analysis of elements' parameters and the measurement of lens performance not only verify the design principle further, but also show the zooming process by the use of two liquid lenses. The system is useful for motion carriers e.g., robot, ground vehicle, and unmanned aerial vehicles considering that it is fast, reliable, and miniature.

  7. An Electrically Tunable Zoom System Using Liquid Lenses

    Directory of Open Access Journals (Sweden)

    Heng Li

    2015-12-01

    Full Text Available A four-group stabilized zoom system using two liquid lenses and two fixed lens groups is proposed. We describe the design principle, realization, and the testing of a 5.06:1 zoom system. The realized effective focal length (EFL range is 6.93 mm to 35.06 mm, and the field of view (FOV range is 8° to 40°. The system can zoom fast when liquid lens 1’s (L1’s optical power take the value from 0.0087 mm−1 to 0.0192 mm−1 and liquid lens 2’s (L2’s optical power take the value from 0.0185 mm−1 to −0.01 mm−1. Response time of the realized zoom system was less than 2.5 ms, and the settling time was less than 15 ms.The analysis of elements’ parameters and the measurement of lens performance not only verify the design principle further, but also show the zooming process by the use of two liquid lenses. The system is useful for motion carriers e.g., robot, ground vehicle, and unmanned aerial vehicles considering that it is fast, reliable, and miniature.

  8. Electrically tunable two-dimensional holographic polymer-dispersed liquid crystal grating with variable period

    Science.gov (United States)

    Wang, Kangni; Zheng, Jihong; Liu, Yourong; Gao, Hui; Zhuang, Songlin

    2017-06-01

    An electrically tunable two-dimensional (2D) holographic polymer-dispersed liquid crystal (H-PDLC) grating with variable period was fabricated by inserting a cylindrical lens in a conventional holographic interference beam. The interference between the plane wave and cylindrical wave resulting in varying intersection angles on the sample, combined with dual exposure along directions perpendicular to each other, generates a 2D H-PDLC grating with varied period. We have identified periods varying from 3.109 to 5.158 μm across a 16 mm width, with supporting theoretical equations for the period. The period exhibits a symmetrical square lattice in a diagonal direction, with an asymmetrical rectangular lattice in off-diagonal locations. With the first exposure at 2 s and the second exposure at 60 s, the phase separation between the prepolymer and liquid crystal was most evident. The diffraction properties and optic-electric characteristics were also studied. The diffraction efficiency of first-order light was observed to be 13.5% without external voltage, and the transmission efficiency of non-diffracted light was 78% with an applied voltage of 100 V. The proposed method provides the capability of generating period variation to the conventional holographic interference path, with potential application in diffractive optics such as tunable multi-wavelength organic lasing from a dye-doped 2D H-PDLC grating.

  9. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium.......We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  10. Electrically tunable microlens arrays based on polarization-independent optical phase of nano liquid crystal droplets dispersed in polymer matrix.

    Science.gov (United States)

    Yu, Ji Hoon; Chen, Hung-Shan; Chen, Po-Ju; Song, Ki Hoon; Noh, Seong Cheol; Lee, Jae Myeong; Ren, Hongwen; Lin, Yi-Hsin; Lee, Seung Hee

    2015-06-29

    Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality.

  11. Electrically Tunable Binary-Phase Fresnel Lens Based on Polymer Dispersed Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Hui LI

    2017-08-01

    Full Text Available This is a proposal for a Fresnel lens with an electrically tunable binary-phase made of polymer dispersed liquid crystal (PDLC, which has relatively fast response time and low applied voltage. Simple fabrication is the major advantage of the proposed method. In this study, NOA65 and E7 were utilized with weight ratios of 60 wt.%: 40 wt.%. There was also the utilization of a relatively low intensity UV-light, 0.53 mW/cm2. The duration time of exposure was about 30 hours. The performance improvement of the Fresnel lens resulted from the infiltration of large LC droplet into the PDLC film. The phenomenon of black cross strip patterns could be explained with the use of the electro-hydrodynamics theory. The diffraction efficiency of the proposed lens was from 31.1 % to 41 % with the changes of externally applied voltage. This work presents an effective approach to get relatively complete phase separation in PDLC. The proposed method also provides great potential in developing high performance Fresnel lens.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.16317

  12. 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....

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  14. Electrically tunable terahertz polarization converter based on overcoupled metal-isolator-metal metamaterials infiltrated with liquid crystals

    Science.gov (United States)

    Vasić, Borislav; Zografopoulos, Dimitrios C.; Isić, Goran; Beccherelli, Romeo; Gajić, Radoš

    2017-03-01

    Large birefringence and its electrical modulation by means of Fréedericksz transition makes nematic liquid crystals (LCs) a promising platform for tunable terahertz (THz) devices. The thickness of standard LC cells is in the order of the wavelength, requiring high driving voltages and allowing only a very slow modulation at THz frequencies. Here, we first present the concept of overcoupled metal-isolator-metal (MIM) cavities that allow for achieving simultaneously both very high phase difference between orthogonal electric field components and large reflectance. We then apply this concept to LC-infiltrated MIM-based metamaterials aiming at the design of electrically tunable THz polarization converters. The optimal operation in the overcoupled regime is provided by properly selecting the thickness of the LC cell. Instead of the LC natural birefringence, the polarization-dependent functionality stems from the optical anisotropy of ultrathin and deeply subwavelength MIM structures. The dynamic electro-optic control of the LC refractive index enables the spectral shift of the resonant mode and, consequently, the tuning of the phase difference between the two orthogonal field components. This tunability is further enhanced by the large confinement of the resonant electromagnetic fields within the MIM cavity. We show that for an appropriately chosen linearly polarized incident field, the polarization state of the reflected field at the target operation frequency can be continuously swept between the north and south pole of the Poincaré sphere. Using a rigorous Q-tensor model to simulate the LC electro-optic switching, we demonstrate that the enhanced light-matter interaction in the MIM resonant cavity allows the polarization converter to operate at driving voltages below 10 Volt and with millisecond switching times.

  15. Liquid crystal tunable metamaterial absorber.

    Science.gov (United States)

    Shrekenhamer, David; Chen, Wen-Chen; Padilla, Willie J

    2013-04-26

    We present an experimental demonstration of electronically tunable metamaterial absorbers in the terahertz regime. By incorporation of active liquid crystal into strategic locations within the metamaterial unit cell, we are able to modify the absorption by 30% at 2.62 THz, as well as tune the resonant absorption over 4% in bandwidth. Numerical full-wave simulations match well to experiments and clarify the underlying mechanism, i.e., a simultaneous tuning of both the electric and magnetic response that allows for the preservation of the resonant absorption. These results show that fundamental light interactions of surfaces can be dynamically controlled by all-electronic means and provide a path forward for realization of novel applications.

  16. Switching frequency response characteristics of a low cost wireless power driving and controlling system for electrically tunable liquid crystal microlenses.

    Science.gov (United States)

    Zhang, Xinyu; Li, Hui; Liu, Kan; Luo, Jun; Xie, Changsheng; Ji, An; Zhang, Tianxu

    2011-01-01

    The essential switching frequency response characteristics of a low cost wireless power driving and controlling system for electrically tunable liquid crystal microlenses (ETLCMs) are obtained. The wireless power system is mainly composed of two coils with different radius and winding as well as a power metal-oxide-semiconductor field effect transistor switch. The voltage response in the small coil, which is connected directly with ETLCMs, is measured and analyzed under the condition of changing some key parameters of the coil system, such as the width of switching frequency region and the duty-cycle of the switching signal ranging from 20% to 80% in intervals of 20%. Through extending the switching frequency range to a few hundreds of kilohertz, an attractive property of only modulating switching frequency to tune precisely the rms voltage in the small coil for ETLCMs is presented. Some interesting phenomena in high frequency regions, for instance, the rms voltage being stable or slightly changed as the frequency, the voltage response cutoff or disappearance after the frequency surpassing a threshold value, and then regeneration after lowering the frequency to lower frequency point than that of generating voltage response cutoff during increasing frequency, are also discovered.

  17. Electrically tunable Fabry-Péerot resonator based on microstructured Si containing liquid crystal

    KAUST Repository

    Tolmachev, Vladimir A.

    2012-01-01

    We have built Fabry-Perot resonators based on microstructured silicon and a liquid crystal. The devices exhibit tuning of the resonance peaks over a wide range, with relative spectral shifts of up to Delta lambda/lambda = 10%. In order to achieve this substantial spectral shift, cavity peaks of high order were used. Under applied voltages of up to 15 V, a variation in the refractive index of the nematic liquid crystal E7 from Delta n(LC) = 0.12 to Delta n(LC) = 0.17 was observed. These results may have practical applications in the near-, mid and far-infrared range.

  18. Polarization-Independent Electrically Tunable Holographic Polymer Dispersed Liquid Crystals Grating Doped with Chiral Molecules

    Directory of Open Access Journals (Sweden)

    Hui LI

    2017-08-01

    Full Text Available This study proposes a holographic grating made of polymer dispersed liquid crystal (PDLC, with a small amount of chiral molecules doped into PDLC material. The major advantage of this grating is that it is independent of light polarization. This characteristic was verified by applying the interference beam intensity of a He-Cd laser at 150 mW/cm2, with an incidence angle between the two interference beams of 24°, for an irradiation curing duration of 120 s. The observed periodic structure of the grating is consistent with the theoretical value. As chiral molecules are doped, nematic-LC experiences a phase-change in the grating. However, the electro-optical features are only slightly affected. This proposed grating has greatly potential in 3D imaging because of its polarization-independent feature.DOI: http://dx.doi.org/10.5755/j01.ms.23.2.16312

  19. 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...... permittivity is calculated and used in finite element mode simulations. The suitability of liquid crystal photonic bandgap fiber devices for filters, waveplates or sensors is highly dependent on the tunability of the transmission spectrum. In this contribution we investigate how the bandgap tunability...... is determined by the parameters of the liquid crystals. This enables us to identify suitable liquid crystals for tunable photonic bandgap fiber devices...

  20. Magnetic field tunable capacitive dielectric:ionic-liquid sandwich composites

    Science.gov (United States)

    Wu, Ye; Bhalla, Amar; Guo, Ruyan

    2016-03-01

    We examined the tunability of the capacitance for GaFeO3-ionic liquid-GaFeO3 composite material by external magnetic and electric field. Up to 1.6 folds of capacitance tunability could be achieved at 957 kHz with voltage 4 V and magnetic field 0.02 T applied. We show that the capacitance enhancement is due to the polarization coupling between dielectric layer and ionic liquid layer.

  1. Electrically tunable zero dispersion wavelengths in photonic crystal fibers filled with a dual frequency addressable liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wahle, Markus, E-mail: markus.wahle@uni-paderborn.de; Kitzerow, Heinz-Siegfried [Department of Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany and Center for Optoelectronics and Photonics Paderborn (CeOPP), Warburger Str. 100, 33098 Paderborn (Germany)

    2015-11-16

    We present a liquid crystal (LC) infiltrated photonic crystal fiber, which enables the electrical tuning of the position of zero dispersion wavelengths (ZDWs). A dual frequency addressable liquid crystal is aligned perpendicular on the inclusion walls of a photonic crystal fiber, which results in an escaped radial director field. The orientation of the LC is controlled by applying an external electric field. Due to the high index of the liquid crystal the fiber guides light by the photonic band gap effect. Multiple ZDWs exist in the visible and near infrared. The positions of the ZDWs can be either blue or red shifted depending on the frequency of the applied voltage.

  2. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures (TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties.

    Science.gov (United States)

    Tang, Jianbo; Zhao, Xi; Li, Jing; Guo, Rui; Zhou, Yuan; Liu, Jing

    2017-10-18

    Metals are excellent choices for electrical- and thermal-current conducting. However, either the stiffness of solid metals or the fluidity of liquid metals could be troublesome when flexibility and formability are both desired. To address this problem, a reliable two-stage route to improve the functionalities of gallium-based liquid metals is proposed. A series of stable semiliquid/semisolid gallium-based liquid metal amalgams with well-controlled particle packing ratios, which we call TransM2ixes, are prepared and characterized. Through effectively packing the liquid metal with copper particles (which are found to turn into intermetallic compound, CuGa2, after dispersing), remarkable enhancements in electrical conductivity (6 × 106 S m-1, ∼80% increase) and thermal conductivity (50 W m-1 K-1, ∼100% increase) are obtained, making the TransM2ixes stand out from current conductive soft materials. The TransM2ixes also exhibit appealing semiliquid/semisolid mechanical behaviors such as excellent adhesion, tunable formability, and self-healing ability. As a class of highly conductive yet editable metallic mixtures, the TransM2ixes demonstrate potential applications in fields like printed and/or flexible electronics and thermal interface materials, as well as other circumstances where the flexibility and conductivity of interfaces and connections are crucial.

  3. Electrically tunable infrared metamaterial devices

    Science.gov (United States)

    Brener, Igal; Jun, Young Chul

    2015-07-21

    A wavelength-tunable, depletion-type infrared metamaterial optical device is provided. The device includes a thin, highly doped epilayer whose electrical permittivity can become negative at some infrared wavelengths. This highly-doped buried layer optically couples with a metamaterial layer. Changes in the transmission spectrum of the device can be induced via the electrical control of this optical coupling. An embodiment includes a contact layer of semiconductor material that is sufficiently doped for operation as a contact layer and that is effectively transparent to an operating range of infrared wavelengths, a thin, highly doped buried layer of epitaxially grown semiconductor material that overlies the contact layer, and a metallized layer overlying the buried layer and patterned as a resonant metamaterial.

  4. Electrically Tunable Plasmonic Resonances with Graphene

    DEFF Research Database (Denmark)

    Emani, Naresh K.; Chung, Ting-Fung; Ni, Xingjie

    2012-01-01

    Real time switching of a plasmonic resonance may find numerous applications in subwavelength optoelectronics, spectroscopy and sensing. We take advantage of electrically tunable interband transitions in graphene to control the strength of the plasmonic resonance.......Real time switching of a plasmonic resonance may find numerous applications in subwavelength optoelectronics, spectroscopy and sensing. We take advantage of electrically tunable interband transitions in graphene to control the strength of the plasmonic resonance....

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

    DEFF Research Database (Denmark)

    Wei, Lei; Eskildsen, Lars; Weirich, Johannes

    2009-01-01

    and corresponding activation loss are measured by using polarized light and a full broadband polarization control setup. The electrically induced phase shift on the Poincaré sphere and corresponding birefringence change are also measured. According to the results, tunable wave plates working in the wavelength range...

  6. Tunable liquid crystal multifocal microlens array.

    Science.gov (United States)

    Algorri, José Francisco; Bennis, Noureddine; Urruchi, Virginia; Morawiak, Przemek; Sánchez-Pena, José Manuel; Jaroszewicz, Leszek R

    2017-12-11

    A novel liquid crystal microlens array with tunable multifocal capability, high optical power and fill-factor is proposed and experimentally demonstrated. A specific hole pattern design produces a multifocal array with only one voltage control. Three operations modes are possible, "Off", "Tunable Multifocal" and "Unifocal". The design is patterned in both substrates. Then, the substrates are arranged in symmetrical configuration. The result is a high optical power in comparison with typical hole patterned structures. Besides, it is proposed a hexagonal pattern that produces a high fill factor, specially indicated for some applications as Integral Imaging. The array has several useful characteristics for this type of application: tunability for the loss of resolution; multifocal for extended DOF; high fill factor for increase the number of views; and low power consumption for integration in portable devices. Moreover, the optical characteristics of the proposed device could bring new applications in other fields.

  7. Magnetocapacitance of an electrically tunable silicene device

    KAUST Repository

    Tahir, M.

    2012-09-26

    Despite their structural similarity, the electronic properties of silicene are fundamentally different from those of well-known graphene due to the strong intrinsic spin orbit interaction and buckled structure of silicene. We address the magnetocapacitance of spin and valley polarized silicene in an external perpendicular magnetic field to clarify the interplay of the spin orbit interaction and the perpendicular electric field. We find that the band gap is electrically tunable and show that the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high magnetic field.

  8. Tunable and rotatable polarization controller using photonic crystal fiber filled with liquid crystal

    DEFF Research Database (Denmark)

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

    2010-01-01

    We design and fabricate a compact tunable and rotatable polarization controller using liquid crystal photonic band gap fibers. The electrically and thermally induced phase shift in the Poincaré sphere and corresponding birefringence change are measured. The direction of the electric field...

  9. Electrically driven and electrically tunable quantum light sources

    Science.gov (United States)

    Lee, J. P.; Murray, E.; Bennett, A. J.; Ellis, D. J. P.; Dangel, C.; Farrer, I.; Spencer, P.; Ritchie, D. A.; Shields, A. J.

    2017-02-01

    Compact and electrically controllable on-chip sources of indistinguishable photons are desirable for the development of integrated quantum technologies. We demonstrate that two quantum dot light emitting diodes (LEDs) in close proximity on a single chip can function as a tunable, all-electric quantum light source. Light emitted by an electrically excited driving LED is used to excite quantum dots in the neighbouring diode. The wavelength of the quantum dot emission from the neighbouring driven diode is tuned via the quantum confined Stark effect. We also show that we can electrically tune the fine structure splitting.

  10. Electrically tunable optofluidic lenses: fabrication and characterization

    NARCIS (Netherlands)

    Mishra, K.

    2016-01-01

    The objective of this research is to fabricate and characterize an adaptive optofluidic lens device with aberration control. In this work, an electric field is employed as a driving tool to manipulate the liquid-liquid interface for suppressing spherical aberration by using a single flat

  11. 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....

  12. Electrically tunable hot-silicon terahertz attenuator

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Minjie [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Vajtai, Robert; Ajayan, Pulickel M. [Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Kono, Junichiro, E-mail: kono@rice.edu [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Department of Physics and Astronomy, Rice University, Houston, Texas 77005 (United States)

    2014-10-06

    We have developed a continuously tunable, broadband terahertz attenuator with a transmission tuning range greater than 10{sup 3}. Attenuation tuning is achieved electrically, by simply changing the DC voltage applied to a heating wire attached to a bulk silicon wafer, which controls its temperature between room temperature and ∼550 K, with the corresponding free-carrier density adjusted between ∼10{sup 11 }cm{sup −3} and ∼10{sup 17 }cm{sup −3}. This “hot-silicon”-based terahertz attenuator works most effectively at 450–550 K (corresponding to a DC voltage variation of only ∼7 V) and completely shields terahertz radiation above 550 K in a frequency range of 0.1–2.5 THz. Both intrinsic and doped silicon wafers were tested and demonstrated to work well as a continuously tunable attenuator. All behaviors can be understood quantitatively via the free-carrier Drude model taking into account thermally activated intrinsic carriers.

  13. Electrically tunable artificial gauge potential for polaritons

    Science.gov (United States)

    Lim, Hyang-Tag; Togan, Emre; Kroner, Martin; Miguel-Sanchez, Javier; Imamoğlu, Atac

    2017-02-01

    Neutral particles subject to artificial gauge potentials can behave as charged particles in magnetic fields. This fascinating premise has led to demonstrations of one-way waveguides, topologically protected edge states and Landau levels for photons. In ultracold neutral atoms, effective gauge fields have allowed the emulation of matter under strong magnetic fields leading to realization of Harper-Hofstadter and Haldane models. Here we show that application of perpendicular electric and magnetic fields effects a tunable artificial gauge potential for two-dimensional microcavity exciton polaritons. For verification, we perform interferometric measurements of the associated phase accumulated during coherent polariton transport. Since the gauge potential originates from the magnetoelectric Stark effect, it can be realized for photons strongly coupled to excitations in any polarizable medium. Together with strong polariton-polariton interactions and engineered polariton lattices, artificial gauge fields could play a key role in investigation of non-equilibrium dynamics of strongly correlated photons.

  14. 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...

  15. A Microwave Tunable Bandpass Filter for Liquid Crystal Applications

    Science.gov (United States)

    Cao, Weiping; Jiang, Di; Liu, Yupeng; Yang, Yuanwang; Gan, Baichuan

    2017-07-01

    In this paper, a novel microwave continuously tunable band-pass filter, based on nematic liquid crystals (LCs), is proposed. It uses liquid crystal (LC) as the electro-optic material to mainly realize frequency shift at microwave band by changing the dielectric anisotropy, when applying the bias voltage. According to simulation results, it achieves 840 MHz offset. Comparing to the existing tunable filter, it has many advantages, such as continuously tunable, miniaturization, low processing costs, low tuning voltage, etc. Thus, it has shown great potentials in frequency domain and practical applications in modern communication.

  16. Optical Properties of Electrically Tunable Two-Dimensional Photonic Lattice Structures Formed in a Holographic Polymer-Dispersed Liquid Crystal Film: Analysis and Experiment

    Directory of Open Access Journals (Sweden)

    Mayu Miki

    2014-05-01

    Full Text Available We report on theoretical and experimental investigations of optical wave propagations in two-dimensional photonic lattice structures formed in a holographic polymer-dispersed liquid crystal (HPDLC film. In the theoretical analysis we employed the 2×2 matrix formulation and the statistical thermodynamics model to analyze the formation of anisotropic photonic lattice structures by holographic polymerization. The influence of multiple reflections inside an HPDLC film on the formed refractive index distribution was taken into account in the analysis. In the experiment we fabricated two-dimensional photonic lattice structures in an HPDLC film under three-beam interference holographic polymerization and performed optical measurements of spectral transmittances and wavelength dispersion. We also demonstrated the electrical control capability of the fabricated photonic lattice structure and its dependence on incident wave polarization. These measured results were compared with the calculated ones by means of photonic band and beam propagation calculations.

  17. Optical Properties of Electrically Tunable Two-Dimensional Photonic Lattice Structures Formed in a Holographic Polymer-Dispersed Liquid Crystal Film: Analysis and Experiment†

    Science.gov (United States)

    Miki, Mayu; Ohira, Ryuichiro; Tomita, Yasuo

    2014-01-01

    We report on theoretical and experimental investigations of optical wave propagations in two-dimensional photonic lattice structures formed in a holographic polymer-dispersed liquid crystal (HPDLC) film. In the theoretical analysis we employed the 2 × 2 matrix formulation and the statistical thermodynamics model to analyze the formation of anisotropic photonic lattice structures by holographic polymerization. The influence of multiple reflections inside an HPDLC film on the formed refractive index distribution was taken into account in the analysis. In the experiment we fabricated two-dimensional photonic lattice structures in an HPDLC film under three-beam interference holographic polymerization and performed optical measurements of spectral transmittances and wavelength dispersion. We also demonstrated the electrical control capability of the fabricated photonic lattice structure and its dependence on incident wave polarization. These measured results were compared with the calculated ones by means of photonic band and beam propagation calculations. PMID:28788643

  18. Optical Properties of Electrically Tunable Two-Dimensional Photonic Lattice Structures Formed in a Holographic Polymer-Dispersed Liquid Crystal Film: Analysis and Experiment.

    Science.gov (United States)

    Miki, Mayu; Ohira, Ryuichiro; Tomita, Yasuo

    2014-05-07

    We report on theoretical and experimental investigations of optical wave propagations in two-dimensional photonic lattice structures formed in a holographic polymer-dispersed liquid crystal (HPDLC) film. In the theoretical analysis we employed the 2×2 matrix formulation and the statistical thermodynamics model to analyze the formation of anisotropic photonic lattice structures by holographic polymerization. The influence of multiple reflections inside an HPDLC film on the formed refractive index distribution was taken into account in the analysis. In the experiment we fabricated two-dimensional photonic lattice structures in an HPDLC film under three-beam interference holographic polymerization and performed optical measurements of spectral transmittances and wavelength dispersion. We also demonstrated the electrical control capability of the fabricated photonic lattice structure and its dependence on incident wave polarization. These measured results were compared with the calculated ones by means of photonic band and beam propagation calculations.

  19. Electrically Tunable Damping of Plasmonic Resonances with Graphene

    DEFF Research Database (Denmark)

    Emani, Naresh K.; Chung, Ting-Fung; Ni, Xingjie

    2012-01-01

    Dynamic switching of a plasmonic resonance may find numerous applications in subwavelength optoelectronics, spectroscopy, and sensing. Graphene shows a highly tunable carrier concentration under electrostatic gating, and this could provide an effective route to achieving electrical control...

  20. Towards liquid crystalline elastomer optically tunable photonic microstructures

    Science.gov (United States)

    Nocentini, S.; Martella, D.; Parmeggiani, C.; Zanotto, S.; Wiersma, D. S.

    2016-09-01

    In this paper we investigate the potentials of liquid crystalline elastomer microstructures for the realization of optically tunable photonic microstructures. While certain limitations regarding the compromise between feature size and structure warping have been observed, it turns out that the simultaneous presence of a refractive index tuning effect and of a shape tuning effect intrinsic to the LCE material can be harnessed to design tunable photonic devices with unique behavior.

  1. Electrically tunable electromagnetic switches based on zero-index metamaterials

    Science.gov (United States)

    Cao, Yanyang; Meng, Qingquan; Xu, Yadong

    2018-02-01

    In this work, we design a heterojunction in a two dimensional parallel-plate metallic waveguide by using zero-index metamaterials and anisotropic dielectrics which are electrically tunable. We show analytically and numerically that by only controlling the direct current voltage applied to the anisotropic dielectrics, the phenomena of perfect transmission and near perfect reflection can be tuned electrically. Such designed junctions can service as electrically tunable switches in waveguide systems, with good performances and high sensitivities. Our work provides another way to electrically control the propagation of electromagnetic waves in waveguide systems.

  2. Plasmonic Gold Nanorod Dispersions with Electrical and Optical Tunability

    Science.gov (United States)

    Grabowski, Christopher; Mahoney, Clare; Park, Kyoungweon; Jawaid, Ali; White, Timothy; Vaia, Richard

    The transmissive, absorptive, electrical, and thermal properties of plasmonic gold nanorods (NRs) have led to their employment in a broad range of applications. These electro-optical properties - governed by their size, shape, and composition - are widely and precisely tunable during synthesis. Gold NRs show promise for large scale optical elements as they have been demonstrated to align faster than liquid crystal films (μs) at low fields (1 V/ μm). Successfully dispersing a high volume fraction of gold NRs requires a strategy to control particle-particle separation and thus avoid aggregation. Herein, we discuss the role of theta temperature and the ability to swell or collapse the chains of polymer-grafted gold NRs to alter the interaction potential between particles. UV-Vis spectroscopy, scattering, and electrical susceptibility characterization methods were employed to determine nanoparticle dispersion along with the degree of gold NR alignment. The development of new agile photonic materials, controllable with both light and electric fields, will help address emerging needs in laser hardening (agile filters) and variable transmission visors.

  3. Comparison between liquid and solid tunable focus lenses

    Energy Technology Data Exchange (ETDEWEB)

    Santiago-Alvarado, A; Cruz-Martinez, V M [Universidad Tecnologica de la Mixteca, Carre. Acatlima Km 2.5 Huajuapan de Leon Oaxaca (Mexico); Vazquez-Montiel, S; Munoz-Lopez, J; Diaz-Gonzalez, G [Instituto Nacional de Astrofisica, Optica y Electronica Luis Enrique Erro 1, Tonantzintla Puebla (Mexico); Campos-Garcia, M, E-mail: santiago@mixteco.utm.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-186, 04510, D.F. Mexico (Mexico)

    2011-01-01

    Nowadays more reports in the use of tunable lenses are reported, it is due to the benefits they offer in optical systems design. A tunable lens is an optical system that can focus on a range of positions by changing dynamically one of its geometric parameters. There are several types of tunable lenses, the most known types are the liquid, the solid elastic, with variable refractive index, and lenses that use a dielectric medium. This paper presents the analysis and opto-mechanical design of two tunable lenses, a liquid lens and another Solid Elastic Lens (SEL). Both lenses are made in mounting aluminium and polydimethylsiloxane (PDMS) as refractor medium, the liquid lens use two elastic membranes containing a liquid medium between them while the SEL only use PDMS material as body of the lens (medium refractor). We describe the opto-mechanical performance of both types of lens highlighting the main features of each. Finally, results of a opto-functional comparison between these prototypes are showed.

  4. Critical electric field for maximum tunability in nonlinear dielectrics

    Science.gov (United States)

    Akdogan, E. K.; Safari, A.

    2006-09-01

    The authors develop a self-consistent thermodynamic theory to compute the critical electric field at which maximum tunability is attained in a nonlinear dielectric. They then demonstrate that the stored electrostatic free energy functional has to be expanded at least up to the sixth order in electric field so as to define the critical field, and show that it depends solely on the fourth and sixth order permittivities. They discuss the deficiency of the engineering tunability metric in describing nonlinear dielectric phenomena, introduce a critical field renormalized tunability parameter, and substantiate the proposed formalism by computing the critical electric field for prototypical 0.9Pb(Mg1/3,Nb2/3)-0.1PbTiO3 and Ba(Ti0.85,Sn0.15)O3 paraelectrics.

  5. Electrically tunable terahertz metamaterials based on graphene stacks array

    Science.gov (United States)

    Liu, Hanqing; Liu, Peiguo; Bian, Li-an; Liu, Chenxi; Zhou, Qihui; Chen, Yuwei

    2017-12-01

    With the ability of tuning chemical potential via gate voltage, the permittivity of graphene stack can be dynamically adjusted over a wide range. In this paper, we design electrically tunable metamaterials based on the graphene/Al2O3 stacks array, which can achieve a good modulation of resonant frequency and peak value in terahertz region. Due to the enlargement of plasmonic resonance response and the broaden distribution of electric field, our proposed structures perform a better tunability compared with traditional metamaterials loaded monolayer graphene. Since the dipole-dipole coupling between adjacent stacks strengthens immensely as reduces the filling factor of array, the modulated capacity could be further improved. It is found that for oblique incidence, the transmission property is also sensitive to the chemical potential of graphene as well as the polarization direction of incident terahertz wave. These results could be very instructive for the potential applications in voltage-sensitive devices, tunable sensors and photovoltaic switches.

  6. A new class of electrically tunable metamaterial terahertz modulators.

    Science.gov (United States)

    Yan, Rusen; Sensale-Rodriguez, Berardi; Liu, Lei; Jena, Debdeep; Xing, Huili Grace

    2012-12-17

    Switchable metamaterials offer unique solutions for efficiently manipulating electromagnetic waves, particularly for terahertz waves, which has been difficult since naturally occurring materials rarely respond to terahertz frequencies controllably. However, few terahertz modulators demonstrated to date exhibit simultaneously low attenuation and high modulation depth. In this letter we propose a new class of electrically-tunable terahertz metamaterial modulators employing metallic frequency-selective-surfaces (FSS) in conjunction with capacitively-tunable layers of electrons, promising near 100% modulation depth and graphene, Si, MoS(2), oxides etc, thus opening up myriad opportunities for realizing high performance switchable metamaterials over an ultra-wide terahertz frequency range.

  7. Electrically Tunable Magnetism in Magnetic Topological Insulators.

    Science.gov (United States)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-17

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators.

  8. Electrically Tunable Magnetism in Magnetic Topological Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-14

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators.

  9. Giant and tunable electric field enhancement in the terahertz regime.

    Science.gov (United States)

    Lu, Xiaoyuan; Wan, Rengang; Wang, Guoxi; Zhang, Tongyi; Zhang, Wenfu

    2014-11-03

    A novel array of slits design combining the nano-slit grating and dielectric-metal is proposed to obtain giant and tunable electric field enhancement in the terahertz regime. The maximum amplitude of electric field is more than 6000 times larger than that of the incident electric field. It is found that the enhancement depends primarily on the stripe and nano-slits width of grating, as well as the thickness of spacer layer. This property is particularly beneficial for the realization of ultra-sensitive nanoparticles detection and nonlinear optics in the terahertz range, such as the second harmonic generation (SHG).

  10. Investigation of tunable terahertz metamaterial perfect absorber with anisotropic dielectric liquid crystal

    Directory of Open Access Journals (Sweden)

    Mohammad P. Hokmabadi

    2017-01-01

    Full Text Available In this letter, we report the unique design, simulation and experimental verification of an electrically tunable THz metamaterial perfect absorber consisting of complementary split ring resonator (CSRR arrays integrated with liquid crystal as the subwavelength spacer in between. We observe a shift in resonance frequency of about 5.0 GHz at 0.567 THz with a 5 V bias voltage at 1KHz between the CSRR and the metal backplane, while the absorbance and full width at half maximum bandwidth are maintained at 90% and 0.025 THz, respectively. Simulated absorption spectrum by using a uniaxial model of LC matches perfectly the experiment data and demonstrates that the effective refractive index of LC changes between 1.5 and 1.7 by sweeping a 1 kHz bias voltage from 0 V to 5 V. By matching simulation and experiment for different bias voltages, we also estimate the angle of LC molecules versus the bias voltage. Additionally, we study the created THz fields inside the spacer to gain a better insight of the characteristics of tunable response of this device. This structure and associated study can support the design of liquid crystal based tunable terahertz detectors and sensors for various applications.

  11. Electrically-Tunable Multi-Color Ultrafast Cherenkov FiberLaser

    DEFF Research Database (Denmark)

    Svane, Ask Sebastian; Liu, Xiaomin; Lægsgaard, Jesper

    2014-01-01

    We demonstrate the broadband electrical tunability of ultrafast fiber laser output across the visible range, from the deep blue to the infrared.......We demonstrate the broadband electrical tunability of ultrafast fiber laser output across the visible range, from the deep blue to the infrared....

  12. Tunable diffraction and self-defocusing in liquid-filled photonic crystal fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.

    2007-01-01

    We suggest and demonstrate a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids. Using the infiltrated cladding region of a photonic crystal fiber as a nonlinear waveguide...... array, we experimentally demonstrate highly tunable beam diffraction and thermal self-defocusing, and realize a compact all-optical power limiter based on a tunable nonlinear response....

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....

  14. Tunable electrical and thermal transport in ice-templated multilayer graphene nanocomposites through freezing rate control.

    Science.gov (United States)

    Schiffres, Scott N; Harish, Sivasankaran; Maruyama, Shigeo; Shiomi, Junichiro; Malen, Jonathan A

    2013-12-23

    We demonstrate tunable electrical and thermal conductivities through freezing rate control in solution-based nanocomposites. For a prototypical suspension of 1 vol % multilayer graphene suspended in hexadecane, the solid-liquid electrical conductivity contrast ratio can be tuned from 1 to 4.5 orders of magnitude for freezing rates between 10(2) and 10(-3) °C/min. We hypothesize that this dramatic variation stems from ice-templating, whereby crystal growth drives nanoparticles into concentrated intercrystal regions, increasing the percolation pathways and reducing the internanoparticle electrical resistance. Optical microscopy supports the ice-templating hypothesis, as these dramatic property changes coincide with changing crystal size. Under the same range of freezing rates, the nanocomposite solid-liquid thermal conductivity contrast ratio varies between 2.3 and 3.0, while pure hexadecane's varies between 2.1 and 2.6. The nanocomposite's thermal conductivity contrast ratios and solid phase enhancements are greater than effective medium theory predictions. We suggest this is due to ice-templating, consistent with our electrical measurements, as well as nanoparticle-induced molecular alignment of alkanes.

  15. Tunable control of antibody immobilization using electric field.

    Science.gov (United States)

    Emaminejad, Sam; Javanmard, Mehdi; Gupta, Chaitanya; Chang, Shuai; Davis, Ronald W; Howe, Roger T

    2015-02-17

    The controlled immobilization of proteins on solid-state surfaces can play an important role in enhancing the sensitivity of both affinity-based biosensors and probe-free sensing platforms. Typical methods of controlling the orientation of probe proteins on a sensor surface involve surface chemistry-based techniques. Here, we present a method of tunably controlling the immobilization of proteins on a solid-state surface using electric field. We study the ability to orient molecules by immobilizing IgG molecules in microchannels while applying lateral fields. We use atomic force microscopy to both qualitatively and quantitatively study the orientation of antibodies on glass surfaces. We apply this ability for controlled orientation to enhance the performance of affinity-based assays. As a proof of concept, we use fluorescence detection to indirectly verify the modulation of the orientation of proteins bound to the surface. We studied the interaction of fluorescently tagged anti-IgG with surface immobilized IgG controlled by electric field. Our study demonstrates that the use of electric field can result in more than 100% enhancement in signal-to-noise ratio compared with normal physical adsorption.

  16. Vector beams generated by tunable liquid crystal polarization holograms

    Science.gov (United States)

    Ruiz, U.; Pagliusi, P.; Provenzano, C.; Cipparrone, G.

    2017-04-01

    Two optically coupled nematic liquid crystal (NLC) polarization holograms (PHs) enable nearly 100% generation efficiency for vector beams (VBs) with spatially variant phase and polarization. Adopting a spatial light modulator assisted holographic approach, the PHs are recorded in the photoaligning substrates of the NLC cell and amplified by the NLC bulk. Owing to negligible NLC absorption at the visible and near infrared wavelengths and the ability to electrically adjust its optical birefringence, a single device allows us to generate VBs with the highest possible efficiency at any wavelength in the transparency range. In particular, we report the generation of VBs with an efficiency of 96% at a wavelength of 633 nm.

  17. Flexible nanoporous tunable electrical double layer biosensors for sweat diagnostics

    Science.gov (United States)

    Munje, Rujuta D.; Muthukumar, Sriram; Panneer Selvam, Anjan; Prasad, Shalini

    2015-09-01

    An ultra-sensitive and highly specific electrical double layer (EDL) modulated biosensor, using nanoporous flexible substrates for wearable diagnostics is demonstrated with the detection of the stress biomarker cortisol in synthetic and human sweat. Zinc oxide thin film was used as active region in contact with the liquid i.e. synthetic and human sweat containing the biomolecules. Cortisol detection in sweat was accomplished by measuring and quantifying impedance changes due to modulation of the double layer capacitance within the electrical double layer through the application of a low orthogonally directed alternating current (AC) electric field. The EDL formed at the liquid-semiconductor interface was amplified in the presence of the nanoporous flexible substrate allowing for measuring the changes in the alternating current impedance signal due to the antibody-hormone interactions at diagnostically relevant concentrations. High sensitivity of detection of 1 pg/mL or 2.75 pmol cortisol in synthetic sweat and 1 ng/mL in human sweat is demonstrated with these novel biosensors. Specificity in synthetic sweat was demonstrated using a cytokine IL-1β. Cortisol detection in human sweat was demonstrated over a concentration range from 10-200 ng/mL.

  18. Liquid Temperature Measurements Using Two Different Tunable Hollow Prisms.

    Science.gov (United States)

    Calixto, Sergio; Rosete-Aguilar, Martha; Torres-Gomez, Ismael

    2017-01-29

    This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other hollow prism is a constant deviation one called a Pellin-Broca. It can be used as a tunable dispersive element in a spectrometer with no moving parts. The application of prisms as temperature sensors is shown.

  19. Tunable liquid microlens array driven by pyroelectric effect: full interferometric characterization

    Science.gov (United States)

    Miccio, Lisa; Grilli, Simonetta; Vespini, Veronica; Ferraro, Pietro

    2008-09-01

    Liquid lenses with adjustable focal length are of great interest in the field of microfluidic devices. They are, usually, realized by electrowetting effect after electrodes patterning on a hydrofobic substrate. Applications are possible in many fields ranging from commercial products such as digital cameras to biological cell sorting. We realized an open array of liquid lenses with adjustable focal length without electrode patterning. We used a z-cut Lithium Niobate crystal (LN) as substrate and few microliters of an oily substance to obtain the droplets array. The spontaneous polarization of LN crystals is reversed by the electric field poling process, thus enabling the realization of periodically poled LN (PPLN) crystals. The substrate consists of a two-dimensional square array of reversed domains with a period around 200 μm. Each domain presents an hexagonal geometry due to the crystal structure. PPLN is first covered by a thin and homogeneous layer of the above mentioned liquid and therefore its temperature is changed by means of a digitally controlled hot plate. During heating and cooling process there is a rearrangement of the liquid layer until it reaches the final topography. Lenses formation is due to the superficial tension changing at the liquid-solid interface by means of the pyroelectric effect. Such effect allows to create a two-dimensional lens pattern of tunable focal length without electrodes. The temporal evolution of both shape and focal length lenses are quantitatively measured by Digital Holographic Microscopy. Array imaging properties and quantitative analysis of the lenses features and aberrations are presented.

  20. Electrically and chemically tunable soft-solid block copolymer structural color (Conference Presentation)

    Science.gov (United States)

    Park, Cheolmin

    2016-09-01

    1D photonic crystals based on the periodic stacking of two different dielectric layers have been widely studied due to their potential use in low-power reflective mode displays, e-books and sensors, but the fabrication of mechanically flexible polymer structural color (SC) films, with electro-active color switching, remains challenging. Here, we demonstrate free-standing electric field tunable ionic liquid swollen block copolymer films. Placement of a polymer/ionic liquid (IL) film-reservoir adjacent to a self-assembled poly(styrene-block-quaternized 2vinyl pyridine) (PS-b-QP2VP) copolymer SC film allowed the development of R, G and B full-color SC block copolymer films by swelling of the QP2VP domains by the ionic liquid associated with water molecules. The IL-polymer/BCP SC film is mechanically flexible with excellent color stability over several days at ambient conditions. The selective swelling of the QP2VP domains could be controlled by both the ratio of the IL to a polymer in the gel-like IL reservoir layer and by an applied voltage in the range of -3V to +6V using a metal/IL reservoir/SC film/IL reservoir/metal capacitor type device.

  1. Realization of electrically tunable single quantum dot nanocavities

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, Felix Florian Georg

    2009-03-15

    We investigated the design, fabrication and optical investigation of electrically tunable single quantum dot-photonic crystal defect nanocavities operating in both the weak and strong coupling regimes of the light matter interaction. We demonstrate that the quantum confined Stark effect can be employed to quickly and reversibly switch the dot-cavity coupling, simply by varying a gate voltage. Our results show that exciton transitions from individual dots can be tuned by up to {proportional_to}4 meV relative to the nanocavity mode, before the emission quenches due to carrier tunneling escape from the dots. We directly probe spontaneous emission, irreversible polariton decay and the statistics of the emitted photons from a single-dot nanocavity in the weak and strong coupling regimes. New information is obtained on the nature of the dot-cavity coupling in the weak coupling regime and electrical control of zero dimensional polaritons is demonstrated for the first time. The structures investigated are p-i-n photodiodes consisting of an 180nm thick free-standing GaAs membrane into which a two dimensional photonic crystal is formed by etching a triangular lattice of air holes. Low mode volume nanocavities (V{sub mode}<1.6 ({lambda}/n){sup 3}) are realized by omitting 3 holes in a line to form L3 cavities and a single layer of InGaAs self-assembled quantum dots is embedded into the midpoint of the membrane. The nanocavities are electrically contacted via 35 nm thick p- and n-doped contact layers in the GaAs membrane. In the weak coupling regime, time resolved spectroscopy reveals a {proportional_to}7 x shortening of the spontaneous emission lifetime as the dot is tuned through the nanocavity mode, due to the Purcell effect. Upon strongly detuning the same quantum dot transition from the nanocavity mode we observe an additional {proportional_to}8 x lengthening of the spontaneous emission lifetime. These observations unequivocally highlight two regimes of dot

  2. Electrically tunable selective reflection of light by heliconical cholesteric structures (Presentation Recording)

    Science.gov (United States)

    Lavrentovich, Oleg D.; Xiang, Jie; Shiyanovskii, Sergij V.; Li, Quan

    2015-10-01

    Cholesteric liquid crystals with helicoidal molecular architecture are known for their ability to selectively reflect light with the wavelength that is determined by the periodicity of molecular orientations. Resulting interference colors are highly saturated, they add like colored lights and produce a color gamut greater than that obtained with inks, dyes, and pigments. The periodicity of the helical structure and thus the wavelength of the reflected light can be controlled by chemical composition and sometimes by temperature, but tuning with the electric field has been so far elusive. Here we demonstrate that by using a cholesteric with oblique helicoidal (heliconical) structure, as opposed to the classic "right-angle" helicoid, one can vary the wavelength of selectively reflected light in a broad spectral range, by simply adjusting the electric field applied parallel to the helicoidal axis. The effect can enable many applications that require dynamically controlled transmission and reflection of light, from energy-saving smart windows to tunable organic lasers, and transparent "see-through" displays. Since the material is non-absorbing and transparent everywhere except the electrically preselected reflection band, the effect can be used in creating multilayered structures with a dynamic additive mixture of colors.

  3. Tunable electronic properties of silicon nanowires under strain and electric bias

    Directory of Open Access Journals (Sweden)

    Alexis Nduwimana

    2014-07-01

    Full Text Available The electronic structure characteristics of silicon nanowires under strain and electric bias are studied using first-principles density functional theory. The unique wire-like structure leads to distinct spatial distribution of carriers, which can be tailored by applying tensile and compressive strains, as well as by an electric bias. Our results indicate that the combined effect of strain and electric bias leads to tunable electronic structures that can be used for piezo-electric devices.

  4. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Science.gov (United States)

    Sansinena, Jose-Maria [Los Alamos, NM; Redondo, Antonio [Los Alamos, NM; Olazabal, Virginia [Los Alamos, NM; Hoffbauer, Mark A [Los Alamos, NM; Akhadov, Elshan A [Los Alamos, NM

    2009-12-29

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  5. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2017-07-18

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  6. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2017-10-31

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  7. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.

    2017-09-12

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  8. Wide tunable shift of the reflection band in dual frequency cholesteric liquid crystals.

    Science.gov (United States)

    Oton, Eva; Netter, Estelle

    2017-06-12

    Technologies featuring external control of reflected and transmitted light are lately being explored for a wide range of optical and photonic applications. Yet, the options for spectral band tuning are scarce, especially if dynamic control of either reflected or transmitted light is required. In this work we demonstrate a tunable device capable of shifting the reflected light spectrum of an impinging light using dual frequency cholesteric liquid crystals. Modulating the frequency of the applied signal, the Bragg reflection can be dynamically shifted over a wide spectral range and also switched off. This feature can be applied to color filters, augmented reality, multi-color lasers or tunable windows.

  9. 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...

  10. Noise filtering in a multi-channel system using a tunable liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal; Scolari, Lara; Tokle, Torger

    2008-01-01

    This paper reports on the first application of a liquid crystal infiltrated photonic bandgap fiber used as a tunable filter in an optical transmission system. The device allows low-cost amplified spontaneous emission (ASE) noise filtering and gain equalization with low insertion loss and broad...... tunability. System experiments show that the use of this filter increases for times the distance over which the optical signal-to-noise ratio (OSNR) is sufficient for error-free transmission with respect to the case in which no filtering is used....

  11. Electrically tunable window based on microwrinkled ZnO/Ag thin film

    Science.gov (United States)

    Shrestha, Milan; Asundi, Anand; Lau, Gih-Keong

    2017-04-01

    Micro-winkling can turn a transparent thin-film of zinc oxide (ZnO) to be `opaque' that can be reversed by unfolding to restore back to the clear state. This principle was previously used to make a mechanically tunable window device. However, ZnO thin film cannot make a compliant electrode to enable electrical unfolding due to its insulator nature. This paper reports the use of multilayer thin films of 10nm silver (Ag) and 30nm thick ZnO to form a compliant electrode with electrically tunable transmittance. A dielectric elastomer actuator (DEA) with a pair of such compliant Ag/ZnO thin films on both sides of a polyacrylate elastomeric membrane (3M VHB 4910) makes an electrically tunable window device. The DEA without radial compression of the elastomer has wrinkle-free electrode. Hence, it is clear with a 47% in-line transmittance (for 550nm wavelength light). In the wrinkled form, under 10% radial compression, it becomes opaque (with less than 1% transmittance). A voltage induced areal expansion of 10% radial strain enables the electrical unfolding of the initial wrinkles. In addition, this device continues to work after 4000 cycles of unfolding and microwrinkling of Ag/ZnO. The performance of electrically tunable window device is comparable to the existing smart window technologies.

  12. Continuous Production of Janus and Composite Liquid Marbles with Tunable Coverage.

    Science.gov (United States)

    Castro, Jasmine O; Neves, Bruna M; Rezk, Amgad R; Eshtiaghi, Nicky; Yeo, Leslie Y

    2016-07-20

    We report a simple method for on-demand continuous processing of composite liquid marbles with the aid of a 3D printed slide platform, which offers the potential for engineering novel functional surfaces for the production of combination drug therapies, particle-based barcode biomarkers and smart membranes, among other applications. Unlike other attempts at producing such liquid marbles, this novel technique not only facilitates controllable and reproducible production of the liquid marbles but also allows the selection of different morphologies such as banded, patchy, and Janus structures by controlling the coalescence conditions, with the possibility for tunable symmetric and asymmetric patterns, the latter by varying the particle species partitioning ratio.

  13. Passive system with tunable group velocity for propagating electrical pulses from sub- to superluminal velocities.

    Science.gov (United States)

    Haché, Alain; Essiambre, Sophie

    2004-05-01

    We report an observation of tunable group velocity from sub-luminal to superluminal in a completely passive system. Electric pulses are sent along a spatially periodic conducting medium containing a punctual nonlinearity, and the resulting amplitude-dependent phase shift allows us to control dispersion and the propagation velocity at the stop band frequency.

  14. Opto-electrical characteristics and tunability of mid-infrared quantum ...

    African Journals Online (AJOL)

    Quantum Cascade Lasers (QCLs) represent advanced technology for Mid-Infra Red (MIR) and Far-Infra Red (FIR) laser sources. Experiments were conducted to investigate the optical and electrical characteristics of Alp-es SB 1487 QCLs. The laser source achieved pulsed power density on a target cavity with tunability ...

  15. Tunable Focus Liquid Lens with Radial-Patterned Electrode

    Directory of Open Access Journals (Sweden)

    Miao Xu

    2015-08-01

    Full Text Available A dielectric liquid lens is prepared based on our previous work. By optimizing the device structure, the liquid lens presents a converging focus with good resolution and changes its focal length over a broad range with a low driving voltage. For a liquid lens with ~2.3 mm diameter in the relaxed state, it can resolve ~40 lp/mm. The resolution does not degrade during focus change. Its focal length can be varied from ~12 to ~5 mm when the applied voltage is changed from 0 to 28 Vrms. The response time of one cycle is ~2.5 s. Our liquid lens, with a low driving voltage for a large dynamic range, has potential applications in imaging, biometrics, optoelectronic, and lab-on-chip devices.

  16. Coal + Biomass → Liquids + Electricity (with CCS)

    Science.gov (United States)

    In this presentation, Matt Aitken applies the MARKet ALlocation energy system model to evaluate the market potential for a class of technologies that convert coal and biomass to liquid fuels and electricity (CBtLE), paired with carbon capture and storage (CCS). The technology is ...

  17. Rayleigh Scattering Measurements Using a Tunable Liquid Crystal Fabry-Perot Interferometer

    Science.gov (United States)

    Mielke-Fagan, Amy F.; Clem, Michelle M.; Elam, Kristie A.

    2010-01-01

    Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous density, velocity, and temperature measurements. The Fabry-Perot interferometer or etalon is a commonly employed instrument for resolving the spectrum of molecular Rayleigh scattered light for the purpose of evaluating these flow properties. This paper investigates the use of a tunable liquid crystal (LC) Fabry-Perot etalon in Rayleigh scattering experiments at NASA Glenn Research Center. The LC etalon provides a robust interferometry system that can be tuned rapidly by adjusting the voltage applied to the liquid crystal interface. Tuning the interferometer is often necessary to control the physical locations of the concentric interference fringes when Rayleigh light is imaged through the LC etalon. The LC etalon diagnostic system was tested in a 1-cm diameter nozzle flow in two different scattering configurations to evaluate its usefulness for Rayleigh measurements compared to a traditional non-tunable fused silica Fabry-Perot etalon.

  18. Obtaining absorption spectra from single textile fibers using a liquid crystal tunable filter microspectrophotometer.

    Science.gov (United States)

    Markstrom, Luke J; Mabbott, Gary A

    2011-06-15

    Visible absorption spectra were recorded for single textile fibers using a microspectrophotometer based on a liquid crystal tunable filter. Spectra compared well with results from a conventional instrument. Some advantages include very fast and simple sample preparation and easy comparison of multiple fibers at the same time. Advantages over extraction-dependent methods include the fact that it is applicable to extremely small sample size, not susceptible to artifacts induced by variable extraction efficiencies, non-destructive, and much easier. Because an immense amount of information is collected in one experiment, good signal averaging is possible, along with multiple comparisons for each data set. The addition of a camera, computer, and liquid crystal tunable filter can transform a standard microscope into a microspectrophotometer capable of performing similar work. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  19. Soft and broadband infrared metamaterial absorber based on gold nanorod/liquid crystal hybrid with tunable total absorption.

    Science.gov (United States)

    Su, Zhaoxian; Yin, Jianbo; Zhao, Xiaopeng

    2015-11-18

    We design a soft infrared metamaterial absorber based on gold nanorods dispersed in liquid crystal (LC) placed on a gold film and theoretically investigate its total absorption character. Because the nanorods align with the LC molecule, the gold nanorods/LC hybrid exhibits different permittivity as a function of tilt angle of LC. At a certain tilt angle, the absorber shows an omnidirectional total absorption effect. By changing the tilt angle of LC by an external electric field, the total absorption character can be adjusted. The total absorption character also depends on the concentration, geometric dimension of nanorods, and defect of nanorod arrangement in LC. When the LC contains different size of gold nanorods, a broadband absorption can be easily realized. The characteristics including flexibility, omnidirectional, broadband and tunability make the infrared metamaterial absorber possess potential use in smart metamaterial devices.

  20. Tunable waveguides based on liquid crystal-infiltrated silicon photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cos, Joaquin; Ferre-Borrull, Josep; Pallares, Josep; Marsal, Lluis F. [Universitat Rovira i Virgili, Nano-electronic and Photonic Systems, Avda. Paisos Catalans 26, 43007 Tarragona (Spain)

    2011-03-15

    A methodology for the study of the practical implementation of tunable waveguides based on Silicon Photonic Crystals with liquid crystal-infiltrated pores is presented. First, by using the FDTD method, the transmission properties of the waveguide depending on the liquid crystal optical axis orientation are studied. Then by means of the plane wave expansion method and taking into account the anisotropy of the photonic crystal components and considering adequate supercells, the transmission or rejection of the optical beam are explained. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Correlation of Electric Field and Critical Design Parameters for Ferroelectric Tunable Microwave Filters

    Science.gov (United States)

    Subramanyam, Guru; VanKeuls, Fred W.; Miranda, Felix A.; Canedy, Chadwick L.; Aggarwal, Sanjeev; Venkatesan, Thirumalai; Ramesh, Ramamoorthy

    2000-01-01

    The correlation of electric field and critical design parameters such as the insertion loss, frequency ability return loss, and bandwidth of conductor/ferroelectric/dielectric microstrip tunable K-band microwave filters is discussed in this work. This work is based primarily on barium strontium titanate (BSTO) ferroelectric thin film based tunable microstrip filters for room temperature applications. Two new parameters which we believe will simplify the evaluation of ferroelectric thin films for tunable microwave filters, are defined. The first of these, called the sensitivity parameter, is defined as the incremental change in center frequency with incremental change in maximum applied electric field (EPEAK) in the filter. The other, the loss parameter, is defined as the incremental or decremental change in insertion loss of the filter with incremental change in maximum applied electric field. At room temperature, the Au/BSTO/LAO microstrip filters exhibited a sensitivity parameter value between 15 and 5 MHz/cm/kV. The loss parameter varied for different bias configurations used for electrically tuning the filter. The loss parameter varied from 0.05 to 0.01 dB/cm/kV at room temperature.

  2. Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

    Directory of Open Access Journals (Sweden)

    Longzhu Cai

    2017-01-01

    Full Text Available A wave interference filtering section that consists of three stubs of different lengths, each with an individual stopband of its own central frequency, is reported here for the design of band-stop filters (BSFs with ultra-wide and sharp stopbands as well as large attenuation characteristics. The superposition of the individual stopbands provides the coverage over an ultra-wide frequency range. Equations and guidelines are presented for the application of a new wave interference technique to adjust the rejection level and width of its stopband. Based on that, an electrically tunable ultra-wide stopband BSF using a liquid crystal (LC material for ultra-wideband (UWB applications is designed. Careful treatment of the bent stubs, including impedance matching of the main microstrip line and bent stubs together with that of the SMA connectors and impedance adaptors, was carried out for the compactness and minimum insertion and reflection losses. The experimental results of the fabricated device agree very well with that of the simulation. The centre rejection frequency as measured can be tuned between 4.434 and 4.814 GHz when a biased voltage of 0–20 Vrms is used. The 3 dB and 25 dB stopband bandwidths were 4.86 GHz and 2.51 GHz, respectively, which are larger than that of other recently reported LC based tunable BSFs.

  3. Heats of vaporization of room temperature ionic liquids by tunable vacuum ultraviolet photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; To, Albert; Koh, Christine; Strasser, Daniel; Kostko, Oleg; Leone, Stephen R.

    2009-11-25

    The heats of vaporization of the room temperature ionic liquids (RTILs) N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide, N-butyl-N-methylpyrrolidinium dicyanamide, and 1-butyl-3-methylimidazolium dicyanamide are determined using a heated effusive vapor source in conjunction with single photon ionization by a tunable vacuum ultraviolet synchrotron source. The relative gas phase ionic liquid vapor densities in the effusive beam are monitored by clearly distinguished dissociative photoionization processes via a time-of-flight mass spectrometer at a tunable vacuum ultraviolet beamline 9.0.2.3 (Chemical Dynamics Beamline) at the Advanced Light Source synchrotron facility. Resulting in relatively few assumptions, through the analysis of both parent cations and fragment cations, the heat of vaporization of N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide is determined to be Delta Hvap(298.15 K) = 195+-19 kJ mol-1. The observed heats of vaporization of 1-butyl-3-methylimidazolium dicyanamide (Delta Hvap(298.15 K) = 174+-12 kJ mol-1) and N-butyl-N-methylpyrrolidinium dicyanamide (Delta Hvap(298.15 K) = 171+-12 kJ mol-1) are consistent with reported experimental values using electron impact ionization. The tunable vacuum ultraviolet source has enabled accurate measurement of photoion appearance energies. These appearance energies are in good agreement with MP2 calculations for dissociative photoionization of the ion pair. These experimental heats of vaporization, photoion appearance energies, and ab initio calculations corroborate vaporization of these RTILs as intact cation-anion ion pairs.

  4. Electric heating effects in nematic liquid crystals

    Science.gov (United States)

    Yin, Y.; Shiyanovskii, S. V.; Lavrentovich, O. D.

    2006-07-01

    Electric heating effects in the nematic liquid crystal change the liquid crystal physical properties and dynamics. We propose a model to quantitatively describe the heating effects caused by dielectric dispersion and ionic conductivity in the nematic liquid crystals upon the application of an ac electric field. The temperature increase of the liquid crystal cell is related to the properties of the liquid crystal such as the imaginary part of the dielectric permittivity, thermal properties of the bounding plates, and the surrounding medium as well as frequency and amplitude of the electric field. To study the temperature dynamics experimentally, we use a small thermocouple inserted directly into the nematic bulk; we assure that the thermocouple does not alter the thermal behavior of the system by comparing the results to those obtained by a noncontact birefringent probing technique recently proposed by Wen and Wu [Appl. Phys. Lett. 86, 231104 (2005)]. We determine how the temperature dynamics and the stationary value of the temperature increase depend on the parameters of the materials and the applied field. We used different surrounding media, from extremely good heat conductors such as aluminum cooling device to extremely poor conductor, Styrofoam; these two provide two limiting cases as compared to typical conditions of nematic cell exploitation in a laboratory or in commercial devices. The experiments confirm the theoretical predictions, namely, that the temperature rise is controlled not only by the heat transfer coefficient of the surrounding medium (as in the previous model) but also by the thickness and the thermal conductivity coefficient of the bounding plates enclosing the nematic layer. The temperature increase strongly depends on the director orientation and can change nonmonotonously with the frequency of the applied field.

  5. Tunable terahertz optical properties of graphene in dc electric fields

    Science.gov (United States)

    Dong, H. M.; Huang, F.; Xu, W.

    2018-03-01

    We develop a simple theoretical approach to investigate terahertz (THz) optical properties of monolayer graphene in the presence of an external dc electric field. The analytical results for optical coefficients such as the absorptance and reflectivity are obtained self-consistently on the basis of a diagrammatic self-consistent field theory and a Boltzmann equilibrium equation. It is found that the optical refractive index, reflectivity and conductivity can be effectively tuned by not only a gate voltage but also a driving dc electric field. This study is relevant to the applications of graphene as advanced THz optoelectronic devices.

  6. Fabrication and characterization of electrically tunable high-Tc superconducting resonators incorporating barium strontium titanate as a tuning material

    Science.gov (United States)

    Lee, E.-H.; Sok, J.; Park, S.-J.; Lee, J.-S.; Song, I.-H.; Kwak, J.; Jung, K.-R.; Kim, J.-Y.; Yoon, S.-Y.; Jeon, D. Y.

    1999-11-01

    We have made the electrically tunable microstrip resonators by using both high-Tc superconducting and dielectric films. The two-pole resonators employ a dielectric barium strontium titanate film on their centre in the form of flip chip. The superconducting YBa2Cu3Oy (YBCO) and dielectric Ba0.1Sr0.9TiO3 were deposited on the CeO2-buffered sapphire substrate and LaAlO3 substrate, respectively, by a pulsed laser deposition technique. Variations of the relative permittivity, icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="TOP"/>r, and dielectric loss tangent, tanicons/Journals/Common/delta" ALT="delta" ALIGN="TOP"/>, of the Ba0.1Sr0.9TiO3 were studied as a function of the applied dc bias at liquid-nitrogen temperature. The tunability, defined as C(0 V)/C(100 V), and loss tangent of the resonators were measured to be ~1.9 and 1.5 × 10-2 (at 100 V), respectively.

  7. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    Science.gov (United States)

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  8. Optofluidic-tunable color filters and spectroscopy based on liquid-crystal microflows.

    Science.gov (United States)

    Cuennet, J G; Vasdekis, A E; Psaltis, D

    2013-07-21

    The integration of color filters with microfluidics has attracted substantial attention in recent years, for on-chip absorption, fluorescence, or Raman analysis. We describe such tunable filters based on the micro-flow of liquid crystals. The filter operation is based on the wavelength-dependent liquid crystal birefringence that can be tuned by modifying the flow velocity field in the microchannel. The latter is possible both temporally and spatially by varying the inlet pressure and the channel geometry, respectively. We explored the use of these optofluidic filters for on-chip absorption spectroscopy in poly(dimethylsiloxane) microfluidic systems; by integrating the distance-dependent color filter with a dye-filled micro-channel, the absorption spectrum of a dye could be measured. Liquid crystal microflows substantially simplify the optofluidic integration, actuation and tuning of color filters for lab-on-a-chip spectroscopic applications.

  9. Electrically tunable plasma excitations in AA-stacking multilayer graphene

    OpenAIRE

    Lin, Ming-Fa; Chuang, Ying-Chih; Wu, Jhao-Ying

    2014-01-01

    We use a tight-binding model and the random-phase approximation to study the Coulomb excitations in simple-hexagonal-stacking multilayer graphene and discuss the field effects. The calculation results include the energy bands, the response functions, and the plasmon dispersions. A perpendicular electric field is predicted to induce significant charge transfer and thus capable of manipulating the energy, intensity, and the number of plasmon modes. This could be further validated by inelastic l...

  10. Electrically Tunable Metamaterials Based on Multimaterial Nanowires Incorporating Transparent Conductive Oxides.

    Science.gov (United States)

    Salary, Mohammad Mahdi; Mosallaei, Hossein

    2017-08-30

    We present novel design approaches for metasurfaces and metamaterials with electrical tunability offering real-time manipulation of light and serving as multifunctional devices in near-infrared frequency regime (at the specific wavelength of 1.55 μm). For this purpose, we integrate indium-tin-oxide (ITO) as a tunable electro-optical material into multimaterial nanowires with metal-oxide-semiconductor and metal-insulator-metal configurations. In particular, an active metasurface operating in the transmission mode is designed which allows for modulation of the transmitted light phase over 280 degrees. This large phase modulation is afforded in the cost of low transmission efficiency. We demonstrate the use of such active metasurfaces for tunable bending and focusing in free-space. Moreover, we investigate the implementation of this material in deeply subwavelength multimaterial nanowires, which can yield strong variations in the effective refractive index by the virtue of internal homogenization enabling tunability of the performance in gradient refractive index metamaterials. In the theoretical modeling of these structures, we adopt a hierarchical multiscale approach by linking drift-diffusion transport model with the electromagnetic model which rigorously characterizes the electro-optical effects.

  11. Electrically tunable plasma excitations in AA-stacked multilayer graphene

    Science.gov (United States)

    Lin, Ming-Fa; Chuang, Ying-Chih; Wu, Jhao-Ying

    2012-09-01

    We use a tight-binding model and the random-phase approximation to study the Coulomb excitations in simple-hexagonal-stacking multilayer graphene and discuss the field effects. The calculation results include the energy bands, the response functions, and the plasmon dispersions. A perpendicular electric field is predicted to induce significant charge transfer and thus is capable of manipulating the energy, intensity, and the number of plasmon modes. This could be further validated by inelastic light scattering or electron-energy-loss spectroscopy.

  12. Tunable liquid-crystal filter for solar imaging at the He i 1083-nm line.

    Science.gov (United States)

    Kopp, G A; Derks, M J; Elmore, D F; Hassler, D M; Woods, J C; Streete, J L; Blankner, J G

    1997-01-01

    A Lyot-Ohman filter for imaging near the solar He i 1083-nm line is described. Fast and continuous spectral tunability is provided by nematic liquid crystals. This solid-state filter has a free spectral range of 2.35 nm and a spectral resolution of 0.135 nm at the operating wavelength of 1083 nm. A wide-fielded design was used for both static and electro-optic retarder elements, facilitating use in fast imaging systems. A first-light He i image of the Sun is presented.

  13. Tunable all-optical devices based on liquid-filled photonic crystal fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis; Neshev, Dragomir N.

    Nonlinear periodic photonic structures offer unique opportunities for manipulating the flow of light by exploiting the interplay between nonlinearity and the discreteness of periodic systems. To fully explore the rich physics and technological potential of periodic and nonlinear optical media......, it is desirable to identify accessible experimental platforms that combine the advantages of high-quality fabricated structures with the attractiveness of tunable and strongly nonlinear materials for light control. In this work we suggest to use liquid-filled photonic crystal fibers (PCFs) for the study...

  14. Electrically tunable superconducting terahertz metamaterial with low insertion loss and high switchable ratios

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun; Zhang, Caihong, E-mail: chzhang@nju.edu.cn; Hu, Guoliang; Zhou, Gaochao; Jiang, Shoulu; Jiang, Chengtao; Zhu, Guanghao; Jin, Biaobing, E-mail: bbjin@nju.edu.cn; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng [Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2016-07-11

    With the emergence and development of artificially structured electromagnetic materials, active terahertz (THz) metamaterial devices have attracted significant attention in recent years. Tunability of transmission is desirable for many applications. For example, short-range wireless THz communications and ultrafast THz interconnects require switches and modulators. However, the tunable range of transmission amplitude of existing THz metamaterial devices is not satisfactory. In this article, we experimentally demonstrate an electrically tunable superconducting niobium nitride metamaterial device and employ a hybrid coupling model to analyze its optical transmission characteristics. The maximum transmission coefficient at 0.507 THz is 0.98 and decreases to 0.19 when the applied voltage increases to 0.9 V. A relative transmittance change of 80.6% is observed, making this device an efficient narrowband THz switch. Additionally, the frequency of the peak is red shifted from 0.507 to 0.425 THz, which means that the device can be used to select the frequency. This study offers an alternative tuning method to existing optical, thermal, magnetic-field, and electric-field tuning, delivering a promising approach for designing active and miniaturized THz devices.

  15. Temperature dependence of electric field tunable ferromagnetic resonance lineshape in multiferroic heterostructure

    Directory of Open Access Journals (Sweden)

    Fenglong Wang

    2016-11-01

    Full Text Available Herein, we experimentally investigate the effect of temperature on the electric field tunable ferromagnetic resonance (FMR in a ferroelectric/ferromagnetic heterostructure, and demonstrate the tuning of abnormal change in FMR using the polarization of the ferroelectric layer above 200 K. The FMR was found to be almost unchanged under different electric field strength at 100 K owing to frozen polarization, which causes extremely weak magnetoelectric coupling. More interestingly, negative effective linewidth was observed when an electric field greater than 10 kV/cm was applied above 220 K. The simultaneous electrical control of magnetization and its damping via FMR based on linear magnetoelectric coupling are directly relevant to use of composite multiferroics for a wide range of devices.

  16. Tunable Zeeman-like Spin Splitting with Liquid Gated Field Effect Transistors

    Science.gov (United States)

    Yuan, Hongtao; Bahramy, M. S.; Morimoto, K.; Shimotani, H.; Arita, R.; Kloc, Ch.; Nagaosa, N.; Iwasa, Y.

    2012-02-01

    Generation of spin polarized electrons is the most critical step for developing spintronics applications. As an electric and nonmagnetic way to realize spin polarization in energy bands, spin-orbit interaction (SOI) has been widely used for spin manipulation in two-dimensional systems. For example, Rashba-type energy splitting with in-plane-polarized spins near γ point of Brillouin zone (BZ) is able to be modulated by electric field through tuning spatial inversion asymmetry. However, Zeeman-type energy splitting with out-of-plane spin polarization is known to be sensitive only to magnetic field and supposed never to be affected by external electric field. In this paper, we theoretically uncover and experimental confirm a perpendicular-electric-field induced giant Zeeman spin splitting at low symmetric K and K' points in a layered chalcogenide, 2H-WSe2. Ab initio band calculation and spin texture indicate that an electric field can make low-energy carriers spin-polarized in a out-of-plane Zeeman-type way and a tunable SOI is able to selectively control the size of splitting. A gate-induced crossover from weak localization to weak antilocalization in the magnetotransport serves as an experimental proof for the tunable SOI and spin polarization. The splitting energy deduced from quantum correction of magnetoconductance is as large as 120 meV and satisfied well with the band calculation for Zeeman-type splitting. This finding directly provides us with a new path-way for electrically initializing and manipulating electron spins for spintronics applications.

  17. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal.

    Science.gov (United States)

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.

  18. Enhancing lab-on-a-chip performance via tunable parallel liquid mircolens arrays

    Science.gov (United States)

    Liu, Ye; Zeng, Xuefeng; Dong, Liang; Jiang, Hongrui

    2009-02-01

    Pathogen detection increasingly shows significance not only for hospital laboratories, but also for in-field usage. Nowadays the microfabrication technologies give us the possibility to integrate optical devices for detection and microfluidic channels for fluorescein-labeled pathogen suspension into a single chip (i.e. optofluidics), thus providing simple, sensitive and inexpensive methods of pathogen detection. One interesting optofluidic component is a microlens whose optical axis is parallel to the substrate used. We hereby report an in situ formed tunable liquid microlens array and its applications for dynamic lab-on-a-chip, such as enhancing fluorescence emission in and detection of laminar fluid flows, and characterizing surface reaction. The de-ionized water microlenses are intrinsically formed via liquid-air interfaces of liquid droplets, whose positions are precisely controlled by air/liquid injection and pinned at T-shaped junctions of octadecyltrichlorosilane(OTS) treated polymerized isobornyl acrylate(poly(IBA)) microchannels. By pneumatic manipulation inside the channel, the microlenses can be separately tuned in focal lengths along the microchannels parallel to the substrate. Then via the tunable microlenses, excitation light is dynamically focused onto fluorescent fluidic samples, and thus the fluorescence emission signal for detection is significantly increased compared to the case without the microlenses, as a result of the enhancement of the fluorescence excitation.Meanwhile, in lab-on-a-chip, controlled microfluidic interfaces are also important, and as our microlens array directly faces the cross sections of these interfaces, we have also shown the potential for surface reaction study at such interfaces by the microlens array.

  19. Liquid toroidal drop under uniform electric field

    Science.gov (United States)

    Zabarankin, Michael

    2017-06-01

    The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ⁡ρ +2 ln ⁡[96 π ]-9 )/ (12 ln ⁡ρ +4 ln ⁡[96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.

  20. Tunable spin-orbit interaction in trilayer graphene exemplified in electric-double-layer transistors.

    Science.gov (United States)

    Chen, Zhuoyu; Yuan, Hongtao; Zhang, Yanfeng; Nomura, Kentaro; Gao, Teng; Gao, Yabo; Shimotani, Hidekazu; Liu, Zhongfan; Iwasa, Yoshihiro

    2012-05-09

    Taking advantage of ultrahigh electric field generated in electric-double-layer transistors (EDLTs), we investigated spin-orbit interaction (SOI) and its modulation in epitaxial trilayer graphene. It was found in magnetotransport that the dephasing length L(φ) and spin relaxation length L(so) of carriers can be effectively modulated with gate bias. As a direct result, SOI-induced weak antilocalization (WAL), together with a crossover from WAL to weak localization (WL), was observed at near-zero magnetic field. Interestingly, among existing localization models, only the Iordanskii-Lyanda-Geller-Pikus theory can successfully reproduce the obtained magnetoconductance well, serving as evidence for gate tuning of the weak but distinct SOI in graphene. Realization of SOI and its large tunability in the trilayer graphene EDLTs provides us with a possibility to electrically manipulate spin precession in graphene systems without ferromagnetics.

  1. Electrically Tunable Absorption Enhancement with Spectral and Polarization Selectivity through Graphene Plasmonic Light Trapping

    Directory of Open Access Journals (Sweden)

    Wenbin Liu

    2016-08-01

    Full Text Available In this paper, anisotropic graphene plasmonic structures are explored for light trapping and absorption enhancement in surrounding media. It is shown that electrically tunable and versatile spectral and polarization selectivity can be realized. Particularly, it is possible to control absorption of the incident light’s polarization component at a specific wavelength by varying the Fermi energy with suitable geometric designs. It may find applications for new types of infrared and THz photodetectors and will promote the research of other novel polarization devices.

  2. Electrically tunable fluidic lens imaging system for laparoscopic fluorescence-guided surgery.

    Science.gov (United States)

    Volpi, Davide; Tullis, Iain D C; Barber, Paul R; Augustyniak, Edyta M; Smart, Sean C; Vallis, Katherine A; Vojnovic, Borivoj

    2017-07-01

    The addition of fluorescence guidance in laparoscopic procedures has gained significant interest in recent years, particularly through the use of near infrared (NIR) markers. In this work we present a novel laparoscope camera coupler based on an electrically tunable fluidic lens that permits programmable focus control and has desirable achromatic performance from the visible to the NIR. Its use extends the lower working distance limit and improves detection sensitivity, important for work with molecularly targeted fluorescence markers. We demonstrate its superior optical performance in laparoscopic fluorescence-guided surgery. In vivo results using a tumor specific molecular probe and a nonspecific NIR dye are presented.

  3. Electrical and thermal tuning of quality factor and free spectral range of optical resonance of nematic liquid crystal microdroplets

    Science.gov (United States)

    Sofi, Junaid Ahmad; Mohiddon, M. A.; Dutta, N.; Dhara, Surajit

    2017-08-01

    We experimentally study the effect of temperature and electric field on the quality (Q ) factor and free spectral range (FSR) of whispering-gallery-mode optical resonance of dye-doped nematic liquid crystal microdroplets. Both the Q factor and the FSR are highly sensitive to the temperature and electric field and are tunable. The Q factor decreases, whereas the FSR increases substantially, with increasing temperature and electric field. The variation of the Q factor and FSR is understood based on the change in the effective refractive index and the dynamic size of the microdroplets.

  4. Liquid methanol under a static electric field

    Science.gov (United States)

    Cassone, Giuseppe; Giaquinta, Paolo V.; Saija, Franz; Saitta, A. Marco

    2015-02-01

    We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm-1) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

  5. Nano-polymer-dispersed liquid crystal as phase modulator for a tunable vertical-cavity surface-emitting laser at 1.55 mum.

    Science.gov (United States)

    Levallois, C; Caillaud, B; de Bougrenet de la Tocnaye, J-L; Dupont, L; Lecorre, A; Folliot, H; Dehaese, O; Loualiche, S

    2006-11-20

    We demonstrate what we believe is the first nonmechanical tunable vertical-cavity surface-emitting laser operating in the C band. This was achieved as a result of the combination of an InGaAs quantum well structure with a 6lambda thickness tunable index nano-polymer-dispersed liquid-crystal material. Experimental results exhibited a potential tunable range close to 10 nm, in the preliminary version, and excellent single mode locking due to the side-mode suppression ratio (more than 20 dB) over the whole spectral range. Another decisive advantage, compared to mechanical solutions, was the tuning response time of a few tens of microseconds (>30 micros) to scan the full spectral range (10 nm), making this device appropriate for some access network functions, as well as being robust and low cost. The voltage values are the main limitation to wavelength range extension. We present a first version of the device optically pumped. The next version will be electrically pumped as required for the access network applications targeted here.

  6. Tunable Anderson localization in hydrogenated graphene based on the electric field effect.

    Science.gov (United States)

    Kang, Joongoo; Wei, Su-Huai

    2013-11-22

    Effective control of hydrogenation of graphene is of great scientific and technological importance. However, the reversible control of H density (n(H)) on graphene is difficult due to the irreversible H2 formation of the detached H adatoms. Here we present a novel mechanism for controlling n(H) by using the unique proton transfer reaction between NH3 gas and hydrogenated graphene, which can be tuned by applying perpendicular electric fields. Using first-principles calculations, we show that n(H) can be reversibly tuned by the applied electric fields around the critical density for the Anderson localization in hydrogenated graphene. The proposed field-induced control of H adsorption or desorption on graphene opens a path toward the development of new graphene transistors based on the tunable degree of disorder.

  7. Tunable Fabry-Pérot filter based on one-dimensional photonic crystals with liquid crystal components

    Science.gov (United States)

    Cos, J.; Ferre-Borrull, J.; Pallares, J.; Marsal, L. F.

    2009-03-01

    A theoretical study of a tunable Fabry-Pérot multilayer structure composed of alternating layers of silicon and liquid crystal is presented and analyzed. The structure possesses two resonant frequencies within the stop band with tunable wavelengths and transmission properties. Tuning is achieved by allowing different orientations of the liquid crystal optical axes within the cavity and within the mirrors, while keeping the optical axes parallel to the layers. Applying the transfer matrix method for thin layers of anisotropic materials we demonstrate that the resonant wavelengths depend on the difference between the liquid crystal optical axis orientations. Besides, we are able to obtain a complete characterization of the structure in the form of its Jones matrix. From this, we propose an optical two-channel equalizer for applications around 1.55 μm that allows tuning the two resonant wavelengths and their relative amplitude levels.

  8. Tunable Mach-Zehnder interferometer in a two-dimensional photonic crystal with liquid crystal infiltration

    Science.gov (United States)

    Chen, Xiyao; Dong, Xinyong; Hu, Juan Juan; Shum, Ping; Wang, Yufei; Qiu, Yishen; Lin, Guimin; Hong, Hailian

    2007-09-01

    A theoretical model of a tunable Mach-Zehnder interferometer (TMZI) constructed in a 2D photonic crystal is proposed. The 2D PhC consists of a square lattice of cylindric air holes in silicon. The TMZI includes two mirrors and two splitters. Lights propagate between them employing self-collimation effect. The two interferometer branches have different path lengths. Parts of the longer branch are infiltrated with a kind of liquid crystal (LC) whose ordinary and extraordinary refractive indices are 1.522 and 1.706, respectively. The transmission spectra at two MZI output ports are in the shape of sinusoidal curves and have a uniform peak spacing 0.0017c/a in the frequency range from 0.26c/a to 0.27c/a. When the effective refractive index n eff of the liquid crystal is increased from 1.522 to 1.706, the peaks shift to the lower frequencies over 0.0017c/a while the peak spacing is almost kept unchanged. So this TMZI can work as a tunble power splitter or an optical switch. For the central operating wavelength around 1550nm, its dimensions are only about tens of microns. So this device may be applied to photonic integrated circuits.

  9. Deposition of gold nanoparticle films using spray pyrolysis technique: Tunability of SPR band by electric field

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Neetesh; Komarala, Vamsi K.; Dutta, Viresh [Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016 (India)

    2012-10-15

    Gold nanoparticle films are prepared using a simple inexpensive spray pyrolysis technique. X-ray as well as TEM diffraction patterns revealed pure cubic structure. The effect of gold nanoparticle concentration on surface plasmon resonance (SPR) band position and bandwidth are investigated for varying spray solution volume. The tunability of SPR band position and bandwidth using an electric field, by applying a voltage (up to 2000 V) to the nozzle, has been demonstrated. The reduced full width at half maximum and blue shift in the SPR band position are observed with {Delta}{lambda}{sub FW} {proportional_to} 55 nm and {Delta}{lambda}{sub P} {proportional_to} 40 nm for the applied voltage of 2 kV. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Electrically tunable and broader-band sound absorption by using micro-perforated dielectric elastomer actuator

    Science.gov (United States)

    Lu, Zhenbo; Shrestha, Milan; Lau, Gih-Keong

    2017-05-01

    Most membrane-type acoustic absorbers for low-frequency sound attenuation are applicable only at a fixed resonant frequency for a narrow bandwidth. Tuning of the acoustic absorption spectrum is desired to match the varying noises. This letter presents a micro-perforated dielectric elastomer actuator (MPDEA) to make a broader-band acoustic absorber electrically tunable. Voltage activation of the MPDEA reduces the membrane tension and hole size and thus enables the active shifting of the acoustic absorption spectrum. Such a membrane tuning method does not require discrete mechanical parts as for the cavity tuning method. Also presented are the analytical models to predict the voltage-induced hole size change and acoustic characteristics of MPDEA.

  11. Tunable Electrical Properties of Vanadium Oxide by Hydrogen-Plasma-Treated Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Helen Hejin Park

    2017-04-01

    Full Text Available In this study, a plasma-modified process was developed to control the electrical properties of atomic layer deposition (ALD-grown vanadium dioxide (VO2, which is potentially useful for applications such as resistive switching devices, bolometers, and plasmonic metamaterials. By inserting a plasma pulse with varying H2 gas flow into each ALD cycle, the insulator-to-metal transition (IMT temperature of postdeposition-annealed crystalline VO2 films was adjusted from 63 to 78 °C. Film analyses indicate that the tunability may arise from changes in grain boundaries, morphology, and compositional variation despite hydrogen not remaining in the annealed VO2 films. This growth method, which enables a systematic variation of the electronic behavior of VO2, provides capabilities beyond those of the conventional thermal ALD and plasma-enhanced ALD.

  12. Polarization tunable circular Dammann grating generated from azo-dye doped nematic liquid crystals

    Science.gov (United States)

    Luo, D.; Dai, H. T.; Sun, X. W.

    2011-03-01

    A polarization tunable circular Dammann grating (CDG) was generated from an azo-dye (Methyl Red from Aldrich) doped liquid crystal (LC, E7 from Merck) cell. A simple multi-exposure photo-aligned process, based on cell assembled with non-rubbing glass substrates, was used to fabricate the binary phase liquid crystal CDG zone plane consisted of even zone with homogenous LC structure and odd zone with TN LC structure. Different twist angle of fabricated TN structure for odd zone can be obtained by adjusting photo exposure intensity or time. CDG with equal-intensity rings was produced through a Fourier-transform and then captured by a charge-coupled-device in our experiment. The maximum 0th and 1st diffraction orders of obtained CDG can be separated achieved by rotating the analyzer's polarization direction. If the chosen analyzer's direction leads to a zero phase difference of output light from even and odd zones, the maximum 0th diffraction order will be achieved, in contrast, if the chosen analyzer's direction leads to a π phase difference of output light from even and odd zones, the maximum 1st diffraction order will be produced. The TN structure of azo-dye doped liquid crystal cell fabricated by photo alignment technique provides a new method to generate CDG with polarization-dependent property. A broad wavelength band of lasers used to generate CDG, if far away from MR azo-dye absorption peak, expands the device's application range and shows a great advantage comparing to previously reported CDG fabricated by fixed materials, where only one fixed working wavelength is allowed.

  13. Wideband Electrically-Pumped 1050 nm MEMS-Tunable VCSEL for Ophthalmic Imaging.

    Science.gov (United States)

    John, Demis D; Burgner, Christopher B; Potsaid, Benjamin; Robertson, Martin E; Lee, Byung Kun; Choi, Woo Jhon; Cable, Alex E; Fujimoto, James G; Jayaraman, Vijaysekhar

    2015-08-15

    In this paper, we present a 1050 nm electrically-pumped micro-electro-mechanically-tunable vertical-cavity-surface-emitting-laser (MEMS-VCSEL) with a record dynamic tuning bandwidth of 63.8 nm, suitable for swept source optical coherence tomography (SS-OCT) imaging. These devices provide reduced cost & complexity relative to previously demonstrated optically pumped devices by obviating the need for a pump laser and associated hardware. We demonstrate ophthalmic SS-OCT imaging with the electrically-pumped MEMS-VCSEL at a 400 kHz axial scan rate for wide field imaging of the in vivo human retina over a 12 mm × 12 mm field and for OCT angiography of the macula over 6 mm × 6 mm & 3 mm × 3 mm fields to show retinal vasculature and capillary structure near the fovea. These results demonstrate the feasibility of electrically pumped MEMS-VCSELs in ophthalmic instrumentation, the largest clinical application of OCT. In addition, we estimate that the 3 dB coherence length in air is 225 meters ± 51 meters, far greater than required for ophthalmic SS-OCT and suggestive of other distance ranging applications.

  14. Tunable fractional-order differentiator using an electrically tuned silicon-on-isolator Mach-Zehnder interferometer.

    Science.gov (United States)

    Zheng, Aoling; Yang, Ting; Xiao, Xi; Yang, Qi; Zhang, Xinliang; Dong, Jianji

    2014-07-28

    We propose and experimentally demonstrate a tunable fractional order photonic differentiator using an on-chip electrically tuned Mach-Zehnder interferometer (MZI) structure. The phase shift at the resonant frequency of the MZI varies when applying different voltages, which can implement the fractional differentiation. Due to the large 3-dB bandwidth of the MZI, the differentiator is expected to have an operation bandwidth of several hundred GHz. The proposed fractional order differentiator is demonstrated experimentally. A Gaussian-like pulse with a bandwidth of about 200 GHz is temporally differentiated with a tunable order range from 0.83 to 1.03.

  15. Invited Article: Electrically tunable silicon-based on-chip microdisk resonator for integrated microwave photonic applications

    Directory of Open Access Journals (Sweden)

    Weifeng Zhang

    2016-11-01

    Full Text Available Silicon photonics with advantages of small footprint, compatibility with the mature CMOS fabrication technology, and its potential for seamless integration with electronics is making a significant difference in realizing on-chip integration of photonic systems. A microdisk resonator (MDR with a strong capacity in trapping and storing photons is a versatile element in photonic integrated circuits. Thanks to the large index contrast, a silicon-based MDR with an ultra-compact footprint has a great potential for large-scale and high-density integrations. However, the existence of multiple whispering gallery modes (WGMs and resonance splitting in an MDR imposes inherent limitations on its widespread applications. In addition, the waveguide structure of an MDR is incompatible with that of a lateral PN junction, which leads to the deprivation of its electrical tunability. To circumvent these limitations, in this paper we propose a novel design of a silicon-based MDR by introducing a specifically designed slab waveguide to surround the disk and the lateral sides of the bus waveguide to suppress higher-order WGMs and to support the incorporation of a lateral PN junction for electrical tunability. An MDR based on the proposed design is fabricated and its optical performance is evaluated. The fabricated MDR exhibits single-mode operation with a free spectral range of 28.85 nm. Its electrical tunability is also demonstrated and an electro-optic frequency response with a 3-dB modulation bandwidth of ∼30.5 GHz is measured. The use of the fabricated MDR for the implementation of an electrically tunable optical delay-line and a tunable fractional-order temporal photonic differentiator is demonstrated.

  16. Invited Article: Electrically tunable silicon-based on-chip microdisk resonator for integrated microwave photonic applications

    Science.gov (United States)

    Zhang, Weifeng; Yao, Jianping

    2016-11-01

    Silicon photonics with advantages of small footprint, compatibility with the mature CMOS fabrication technology, and its potential for seamless integration with electronics is making a significant difference in realizing on-chip integration of photonic systems. A microdisk resonator (MDR) with a strong capacity in trapping and storing photons is a versatile element in photonic integrated circuits. Thanks to the large index contrast, a silicon-based MDR with an ultra-compact footprint has a great potential for large-scale and high-density integrations. However, the existence of multiple whispering gallery modes (WGMs) and resonance splitting in an MDR imposes inherent limitations on its widespread applications. In addition, the waveguide structure of an MDR is incompatible with that of a lateral PN junction, which leads to the deprivation of its electrical tunability. To circumvent these limitations, in this paper we propose a novel design of a silicon-based MDR by introducing a specifically designed slab waveguide to surround the disk and the lateral sides of the bus waveguide to suppress higher-order WGMs and to support the incorporation of a lateral PN junction for electrical tunability. An MDR based on the proposed design is fabricated and its optical performance is evaluated. The fabricated MDR exhibits single-mode operation with a free spectral range of 28.85 nm. Its electrical tunability is also demonstrated and an electro-optic frequency response with a 3-dB modulation bandwidth of ˜30.5 GHz is measured. The use of the fabricated MDR for the implementation of an electrically tunable optical delay-line and a tunable fractional-order temporal photonic differentiator is demonstrated.

  17. Recent advances in liquid mixtures in electric fields

    Science.gov (United States)

    Katsir, Yael; Tsori, Yoav

    2017-02-01

    When immiscible liquids are subject to electric fields interfacial forces arise due to a difference in the permittivity or the conductance of the liquids, and these forces lead to shape change in droplets or to interfacial instabilities. In this topical review we discuss recent advances in the theory and experiments of liquids in electric fields with an emphasis on liquids which are initially miscible and demix under the influence of an external field. In purely dielectric liquids demixing occurs if the electrode geometry leads to sufficiently large field gradients. In polar liquids field gradients are prevalent due to screening by dissociated ions irrespective of the electrode geometry. We examine the conditions for these ‘electro prewetting’ transitions and highlight few possible systems where they might be important, such as in stabilization of colloids and in gating of pores in membranes.

  18. OPERATION OF THE ELECTRIC ARC FURNACE WITH LIQUID RESIDUES METAL

    Directory of Open Access Journals (Sweden)

    A. B. Steblov

    2016-01-01

    Full Text Available Investigations have shown a positive impact of increasing the mass of the liquid residue (swamps in an electric arc furnace EAF-160, from 10 to 20–30 tonnes on increasing of usable output and reducing the specific energy consumption per ton of liquid metal.

  19. Tunable amplified spontaneous emission in graphene quantum dots doped cholesteric liquid crystals

    Science.gov (United States)

    Cao, Mingxuan; Yang, Siwei; Zhang, Yating; Song, Xiaoxian; Che, Yongli; Zhang, Haiting; Yu, Yu; Ding, Guqiao; Zhang, Guizhong; Yao, Jianquan

    2017-06-01

    Graphene quantum dots (GQDs) have received much research attention, because of their useful structure and optical absorption/emission. We report the tunable amplified spontaneous emission (ASE) in GQD-doped cholesteric liquid crystal (CLC), which to the best of our knowledge has not been previously observed. The GQDs are uniformly dispersed with a weight ratio of 0.5 wt.% in CLC. Under optical excitation, typical ASE is triggered in the system at pump energies greater than 1.25 mJ cm-2. The emission peak at the long wavelength edge of the photonic bandgap shifts from 662 to 669 nm, as the working temperature is increased from 50 to 90 °C. The preparation of the combined GQDs and CLC is simple and low-cost, and the resulting material is photostable and non-toxic. Combining the GQD gain material with the self-assembled CLC resonator has potential in the fabrication of ASE source and laser devices.

  20. Optoelectronic devices based on electrically tunable p-n diodes in a monolayer dichalcogenide

    Science.gov (United States)

    Baugher, Britton W. H.; Churchill, Hugh O. H.; Yang, Yafang; Jarillo-Herrero, Pablo

    2014-04-01

    The p-n junction is the functional element of many electronic and optoelectronic devices, including diodes, bipolar transistors, photodetectors, light-emitting diodes and solar cells. In conventional p-n junctions, the adjacent p- and n-type regions of a semiconductor are formed by chemical doping. Ambipolar semiconductors, such as carbon nanotubes, nanowires and organic molecules, allow for p-n junctions to be configured and modified by electrostatic gating. This electrical control enables a single device to have multiple functionalities. Here, we report ambipolar monolayer WSe2 devices in which two local gates are used to define a p-n junction within the WSe2 sheet. With these electrically tunable p-n junctions, we demonstrate both p-n and n-p diodes with ideality factors better than 2. Under optical excitation, the diodes demonstrate a photodetection responsivity of 210 mA W-1 and photovoltaic power generation with a peak external quantum efficiency of 0.2%, promising values for a nearly transparent monolayer material in a lateral device geometry. Finally, we demonstrate a light-emitting diode based on monolayer WSe2. These devices provide a building block for ultrathin, flexible and nearly transparent optoelectronic and electronic applications based on ambipolar dichalcogenide materials.

  1. Quantum electric-dipole liquid on a triangular lattice.

    Science.gov (United States)

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F; Sun, Young

    2016-02-04

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics.

  2. Electrically Tuned Microwave Devices Using Liquid Crystal Technology

    Directory of Open Access Journals (Sweden)

    Pouria Yaghmaee

    2013-01-01

    Full Text Available An overview of liquid crystal technology for microwave and millimeter-wave frequencies is presented. The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies. This paper describes physical theory and fundamental electrical properties arising from the anisotropy of liquid crystals and overviews selected realized liquid crystal devices, throughout four main categories: resonators and filters, phase shifters and delay lines, antennas, and, finally, frequency-selective surfaces and metamaterials.

  3. Electrically tunable surface plasmon for THz emission, detection, and other applications

    Science.gov (United States)

    Khoury, Jed; Haji-Saeed, Bahareh; Buchwald, Walter; Woods, Charles

    2010-08-01

    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  4. Focal length calibration of an electrically tunable lens by digital holography.

    Science.gov (United States)

    Wang, Zhaomin; Qu, Weijuan; Yang, Fang; Asundi, Anand Krishna

    2016-02-01

    The electrically tunable lens (ETL) is a novel current-controlled adaptive optical component which can continuously tune its focus in a specific range via changing its surface curvature. To quantitatively characterize its tuning power, here we assume the ETL to be a pure phase object and present a novel calibration method to dynamically measure its wavefront by use of digital holographic microscopy (DHM). The least squares method is then used to fit the radius of curvature of the wavefront. The focal length is obtained by substituting the radius into the Zemax model of the ETL. The behavior curve between the focal length of the ETL and its driven current is drawn, and a quadratic mathematic model is set up to characterize it. To verify our model, an ETL and offset lens combination is proposed and applied to ETL-based transport of intensity equation (TIE) phase retrieval microscopy. The experimental result demonstrates the calibration works well in TIE phase retrieval in comparison with the phase measured by DHM.

  5. Terahertz beam switching by electrical control of graphene-enabled tunable metasurface.

    Science.gov (United States)

    Zhang, Yin; Feng, Yijun; Zhao, Junming; Jiang, Tian; Zhu, Bo

    2017-10-26

    Controlling the terahertz wave, especially the dynamical and full control of terahertz wavefront, is highly demanded due to the increasing development of practical devices and application systems. Recently considerable efforts have been made to fill the 'terahertz gap' with the help of artificial metamaterial or metasurface incorporated with graphene material. Here, we propose a scheme to design tunable metasurface consisting of metallic patch array on a grounded polymer substrate embedded with graphene layers to electrically control the electromagnetic beam reflection at terahertz frequency. By adjusting geometric dimension of the patch elements, 360 degree reflection phase range may be achieved, thus abrupt phase shifts can be introduced along the metasurface for tailoring the reflected wavefront. Moreover, the reflective phase gradient over the metasurface can be switched between 90 and 360 degree by controlling the Fermi energy of the embedded graphene through voltage biasing, hence dynamically switching the reflective beam directions. Numerical simulations demonstrate that either single beam or dual beam dynamically switching between normal and oblique reflection angles can be well attained at working frequency. The proposed approach will bring much freedom in the design of beam manipulation devices and may be applied to terahertz radiation control.

  6. Thermophysical Properties of Liquid Te: Density, Electrical Conductivity, and Viscosity

    Science.gov (United States)

    Li, C.; Su, C.; Lehoczky, S. L.; Scripa, R. N.; Ban, H.; Lin, B.

    2004-01-01

    The thermophysical properties of liquid Te, namely, density, electrical conductivity, and viscosity, were determined using the pycnometric and transient torque methods from the melting point of Te (723 K) to approximately 1150 K. A maximum was observed in the density of liquid Te as the temperature was increased. The electrical conductivity of liquid Te increased to a constant value of 2.89 x 10(exp 5 OMEGA-1m-1) as the temperature was raised above 1000 K. The viscosity decreased rapidly upon heating the liquid to elevated temperatures. The anomalous behaviors of the measured properties are explained as caused by the structural transitions in the liquid and discussed in terms of Eyring's and Bachiskii's predicted behaviors for homogeneous liquids. The Properties were also measured as a function of time after the liquid was coded from approximately 1173 or 1123 to 823 K. No relaxation phenomena were observed in the properties after the temperature of liquid Te was decreased to 823 K, in contrast to the relaxation behavior observed for some of the Te compounds.

  7. Liquid Metal Thermal Electric Converter bench test module

    Energy Technology Data Exchange (ETDEWEB)

    Lukens, L.L.; Andraka, C.E.; Moreno, J.B.

    1988-04-01

    This report describes the design, fabrication, and test of a Liquid Metal Thermal Electric Converter Bench Test Module. The work presented in this document was conducted as a part of Heat Engine Task of the US Department of Energy's (DOE) Solar Thermal Technology Program. The objective of this task is the development and evaluation of heat engine technologies applicable to distributed receiver systems, in particular, dish electric systems.

  8. Electrically and Thermally Insulated Joint for Liquid Nitrogen Transfer

    DEFF Research Database (Denmark)

    Rasmussen, Carsten; Jensen, Kim Høj; Holbøll, Joachim T.

    1999-01-01

    A prototype of a superconducting cable is currently under construction. The cable conductor is cooled by liquid nitrogen in order to obtain superconductivity. The peripheral cooling circuit is kept at ground potential. This requires a joint which insulates both electrically and thermally...

  9. 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 core diameter of 25mm, and a bandgap tuning sensitivity of 27nm/°C at room temperature. The insertion loss is estimated to be less than 0.5dB.......We demonstrate a highly tunable photonic bandgap fiber, which has a core diameter of 25mm, and a bandgap tuning sensitivity of 27nm/°C at room temperature. The insertion loss is estimated to be less than 0.5dB....

  10. High performance liquid chromatography with mid-infrared detection based on a broadly tunable quantum cascade laser.

    Science.gov (United States)

    Beskers, Timo F; Brandstetter, Markus; Kuligowski, Julia; Quintás, Guillermo; Wilhelm, Manfred; Lendl, Bernhard

    2014-05-07

    This work introduces a tunable mid-infrared (mid-IR) external cavity quantum cascade laser (EC-QCL) as a new molecular specific detector in liquid chromatography. An EC-QCL with a maximum tunability of 200 cm(-1) (1030-1230 cm(-1)) was coupled to isocratic high performance liquid chromatography (HPLC) for the separation of sugars with a cation exchange column (counter ion: Ca(2+)) and distilled water as the mobile phase. Transmission measurements in a 165 μm thick flow cell allowed for on-line coupling and independent quantification of glucose, fructose and sucrose in the concentration range from 5 mg mL(-1) to 100 mg mL(-1) in several beverages. The results obtained with the EC-QCL detector were found to be in good agreement with those obtained using a differential refractive index detector as a reference. The standard deviation of the method for the linear calibration was better than 5 mg mL(-1) for all sugars and reached a minimum of 1.9 mg mL(-1), while the DRI detector reached a minimum of 1 mg mL(-1). Besides the quantification of sugars for which a calibration was performed, also chromatographic peaks of other components could be identified on the basis of their IR absorption spectra. This includes taurine, ethanol, and sorbitol.

  11. Liquid metal actuation by electrical control of interfacial tension

    Science.gov (United States)

    Eaker, Collin B.; Dickey, Michael D.

    2016-09-01

    By combining metallic electrical conductivity with low viscosity, liquid metals and liquid metal alloys offer new and exciting opportunities to serve as reconfigurable components of electronic, microfluidic, and electromagnetic devices. Here, we review the physics and applications of techniques that utilize voltage to manipulate the interfacial tension of liquid metals; such techniques include electrocapillarity, continuous electrowetting, electrowetting-on-dielectric, and electrochemistry. These techniques lower the interfacial tension between liquid metals and a surrounding electrolyte by driving charged species (or in the case of electrochemistry, chemical species) to the interface. The techniques are useful for manipulating and actuating liquid metals at sub-mm length scales where interfacial forces dominate. We focus on metals and alloys that are liquid near or below room temperature (mercury, gallium, and gallium-based alloys). The review includes discussion of mercury—despite its toxicity—because it has been utilized in numerous applications and it offers a way of introducing several phenomena without the complications associated with the oxide layer that forms on gallium and its alloys. The review focuses on the advantages, applications, opportunities, challenges, and limitations of utilizing voltage to control interfacial tension as a method to manipulate liquid metals.

  12. High yield and ultrafast sources of electrically triggered entangled-photon pairs based on strain-tunable quantum dots.

    Science.gov (United States)

    Zhang, Jiaxiang; Wildmann, Johannes S; Ding, Fei; Trotta, Rinaldo; Huo, Yongheng; Zallo, Eugenio; Huber, Daniel; Rastelli, Armando; Schmidt, Oliver G

    2015-12-01

    Triggered sources of entangled photon pairs are key components in most quantum communication protocols. For practical quantum applications, electrical triggering would allow the realization of compact and deterministic sources of entangled photons. Entangled-light-emitting-diodes based on semiconductor quantum dots are among the most promising sources that can potentially address this task. However, entangled-light-emitting-diodes are plagued by a source of randomness, which results in a very low probability of finding quantum dots with sufficiently small fine structure splitting for entangled-photon generation (∼10(-2)). Here we introduce strain-tunable entangled-light-emitting-diodes that exploit piezoelectric-induced strains to tune quantum dots for entangled-photon generation. We demonstrate that up to 30% of the quantum dots in strain-tunable entangled-light-emitting-diodes emit polarization-entangled photons. An entanglement fidelity as high as 0.83 is achieved with fast temporal post selection. Driven at high speed, that is 400 MHz, strain-tunable entangled-light-emitting-diodes emerge as promising devices for high data-rate quantum applications.

  13. Heavily Cr-doped (Bi,Sb2Te3 as a ferromagnetic insulator with electrically tunable conductivity

    Directory of Open Access Journals (Sweden)

    Yunbo Ou

    2016-08-01

    Full Text Available With molecular beam epitaxy we have grown Cry(BixSb1-x2-yTe3 thin films with homogeneous distribution of Cr dopants and Curie temperature up to 77 K. The films with Cr concentration y ≥ 0.39 are found to be topologically trivial, highly insulating ferromagnets, whose conductivity can be tuned over two orders of magnitude by gate voltage. The ferromagnetic insulators with electrically tunable conductivity can be used to realize the quantum anomalous Hall effect at higher temperature in topological insulator heterostructures and to develop field effect devices for spintronic applications.

  14. Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

    Science.gov (United States)

    Anand, Madhu

    Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Materials built from nanoparticles possess unique chemical, physical, mechanical and optical properties. Due to these properties, they hold potential in application areas such as catalysts, sensors, semiconductors and optics. At the same time, CO 2 in the form of supercritical fluid or CO2 gas-expanded liquid mixtures has gained significant attention in the area of processing nanostructures. This dissertation focuses on the synthesis and processing of nanoparticles using CO2 tunable solvent systems. Nanoparticle properties depend heavily on their size and, as such, the ability to finely control the size and uniformity of nanoparticles is of utmost importance. Solution based nanoparticle formation techniques are attractive due to their simplicity, but they often result in the synthesis of particles with a wide size range. To address this limitation, a post-synthesis technique has been developed in this dissertation to fractionate polydisperse nanoparticles ( s . = 30%) into monodisperse fractions ( s . = 8%) using tunable physicochemical properties of CO 2 expanded liquids, where CO2 is employed as an antisolvent. This work demonstrates that by controlling the addition of CO2 (pressurization) to an organic dispersion of nanoparticles, the ligand stabilized nanoparticles can be size selectively precipitated within a novel high pressure apparatus that confines the particle precipitation to a specified location on a surface. Unlike current techniques, this CO2 expanded liquid approach provides faster and more efficient particle size separation, reduction in organic solvent usage, and pressure tunable size selection in a single process. To improve our fundamental understanding and to further refine the size separation process, a detailed study has been performed to identify the key parameters enabling size separation of various

  15. Electrically controlled optical bandgap in a twisted photonic liquid crystal

    Science.gov (United States)

    Molina, Ismael; Adrián Reyes, J.; Avendaño, Carlos G.

    2011-06-01

    We consider a one-dimensional twisted photonic liquid crystal, which consists of N nematic liquid crystal slabs in a twisted configuration alternated by N isotropic dielectric layers under the action of a dc electric field (Edc) aligned along the periodicity axis. We write and solve numerically the corresponding Euler-Lagrange equations describing the nematic layer configuration. We express Maxwell's equations in a 4×4 matrix representation, and by using the transfer matrix formalism, we obtain the optical band structures at arbitrary incidence angles and different external electric fields. We have found that there exists a strong dependence of electric field on the transmission and reflection spectra in enhancing and extinguishing bandgaps. The analysis presented here allow us to propose an electrically shiftable universal rejection filter for incident waves of left- and right-circular polarization. It is observed that by increasing the electric field we can highly enhance the cross-polarized reflection bandgaps and suppress the co-polarized ones. We analyzed the optical spectra for different values of twist angle, different ratios between dielectric and nematic layer thicknesses and number of layers N. Also, we showed that the cross-polarized bandgaps are blue-shifted as the incidence angle gets larger.

  16. 30 CFR 57.4160 - Underground electric substations and liquid storage facilities.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground electric substations and liquid... Underground electric substations and liquid storage facilities. The requirements of this standard apply to...) Electric substations. (2) Unburied, combustible liquid storage tanks. (3) Any group of containers used for...

  17. Laser ablation of titanium in liquid in external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

    2015-09-01

    Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.

  18. Quantitative evaluation on activated property-tunable bulk liquid water with reduced hydrogen bonds using deconvoluted Raman spectroscopy.

    Science.gov (United States)

    Chen, Hsiao-Chien; Mai, Fu-Der; Yang, Kuang-Hsuan; Chen, Liang-Yih; Yang, Chih-Ping; Liu, Yu-Chuan

    2015-01-06

    Interesting properties of water with distinguishable hydrogen-bonding structure on interfacial phase or in confined environment have drawn wide attentions. However, these unique properties of water are only found within the interfacial phase and confined environment, thus, their applications are limited. In addition, quantitative evaluation on these unique properties associating with the enhancement of water's physical and chemical activities represents a notable challenge. Here we report a practicable production of free-standing liquid water at room temperature with weak hydrogen-bonded structure naming Au nanoparticles (NPs)-treated (AuNT) water via treating by plasmon-induced hot electron transfer occurred on resonantly illuminated gold NPs (AuNPs). Compared to well-known untreated bulk water (deionized water), the prepared AuNT water exhibits many distinct activities in generally physical and chemical reactions, such as high solubilities to NaCl and O2. Also, reducing interaction energy within water molecules provides lower overpotential and higher efficiency in electrolytic hydrogen production. In addition, these enhanced catalytic activities of AuNT water are tunable by mixing with deionized water. Also, most of these tunable activities are linearly proportional to its degree of nonhydrogen-bonded structure (DNHBS), which is derived from the O-H stretching in deconvoluted Raman spectrum.

  19. Electrically tunable switching based on photonic-crystal waveguide loaded graphene stacks

    Science.gov (United States)

    Liu, Hanqing; Liu, Peiguo; Bian, Li-an; Liu, Chenxi; Zhou, Qihui; Dong, Yanfei

    2018-03-01

    Through applying gate voltage to tune the chemical potential of graphene, the relative permittivity of multilayer graphene/Al2O3 stack can be dynamically adjusted over a wide range. In this paper, we mainly design novel photonic-crystal waveguides based on graphene stacks including a side-coupled waveguide with two defect cavities as well as a two-channel multiport waveguide, and aim to modulate the propagation of incident light wave via controlling the permittivity of graphene stack. It is demonstrated according to simulations that tunable switching property can be achieved in our proposed structures, such as blue shift of resonant stopband, adjustable coupled-resonator-induced transparency, and tunability of output quantity. These results could be very instructive for the potential applications in high-density integrated optical devices, photoelectric transducer, and laser pulse limiters.

  20. A new tunable dispersive liquid-liquid micro extraction method developed for the simultaneous preconcentration of lead and cadmium from lakes water: a multivariate study

    Science.gov (United States)

    Bilal, Muhammad; Kazi, Tasneem Gul; Afridi, Hassan Imran; Ali, Jamshed; Baig, Jameel Ahmed; Arain, Mohammad Balal; Khan, Mustafa

    2017-08-01

    A green tunable dispersive liquid-liquid micro extraction (TDLLME) technique was established for the simultaneous enrichment of lead (Pb) and cadmium (Cd) from different lakes water before analysis by flame atomic absorption spectrometry (FAAS). A solvent known as tunable polarity solvent (TPS), mixture of 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) and 1-decanol, has been employed as extractant in aqueous medium. In first step this mixture can be made polar by slowly bubbling the antisolvent trigger (CO2) through the solution, which makes a monophasic solution. During this step hydrophobic complexes of the metals with 8-hydroxy quinoline (8-HQ) were extracted by TPS. Then the mixture was switched back to hydrophobic one by heating and/or bubbling nitrogen, turning the mixture into two phases again. In second phase the metals were leached out from the complexes entrapped in TPS, by treating with a solution of nitric acid and exposing the mixture to CO2, which switched the mixture into single phase. Then N2 purging and/or heating again turned the mixture into two phases. The acidic aqueous phase containing the metals was introduced to FAAS for analysis, whereas TPS was recycled for next experiment. Different parameters, affecting the efficiency the technique, were optimized by multivariate approach. The method was applied to certified reference material of water and to a real sample spiked with standards of known concentration, to confirm its validity and accuracy. LOD obtained for Pb and Cd were 0.560 and 0.056 μg L- 1 respectively. The developed method was applied successfully to the real water samples of two lakes of Sindh, Pakistan.

  1. Quantum-confinement and Structural Anisotropy result in Electrically-Tunable Dirac Cone in Few-layer Black Phosphorous.

    Science.gov (United States)

    Dolui, Kapildeb; Quek, Su Ying

    2015-07-01

    Two-dimensional (2D) materials are well-known to exhibit interesting phenomena due to quantum confinement. Here, we show that quantum confinement, together with structural anisotropy, result in an electric-field-tunable Dirac cone in 2D black phosphorus. Using density functional theory calculations, we find that an electric field, E ext, applied normal to a 2D black phosphorus thin film, can reduce the direct band gap of few-layer black phosphorus, resulting in an insulator-to-metal transition at a critical field, Ec. Increasing E ext beyond Ec can induce a Dirac cone in the system, provided the black phosphorus film is sufficiently thin. The electric field strength can tune the position of the Dirac cone and the Dirac-Fermi velocities, the latter being similar in magnitude to that in graphene. We show that the Dirac cone arises from an anisotropic interaction term between the frontier orbitals that are spatially separated due to the applied field, on different halves of the 2D slab. When this interaction term becomes vanishingly small for thicker films, the Dirac cone can no longer be induced. Spin-orbit coupling can gap out the Dirac cone at certain electric fields; however, a further increase in field strength reduces the spin-orbit-induced gap, eventually resulting in a topological-insulator-to-Dirac-semimetal transition.

  2. Liquid-Phase Electrical Discharges: Fundamental Mechanisms and Applications

    Science.gov (United States)

    Franclemont, Joshua

    The increased demand in alternative energy in recent decades has generated significant interest in cleaner fuel sources including hydrogen and syngas (hydrogen and carbon monoxide). Hydrogen and syngas are both primarily produced through the steam reforming of hydrocarbons, specifically natural gas. Although other processes are known, the cheapest source of these fuels is currently through the heating of natural gas in the presence of steam and a catalyst. However, due to the emissions associated with the steam reforming of natural gas and the lack of low cost, efficient, and reliable onboard hydrogen storage technologies for fuel cell powered vehicles, attention has been focused on plasma-assisted reforming of hydrocarbons. Plasma processes can be implemented onboard and are able to directly reform liquid hydrocarbons and alcohols without external heating or catalysts. In addition to hydrogen and syngas, the plasma-assisted reforming of hydrocarbons and alcohols offers other desirable products such as C2 gases (ethane, ethylene, and acetylene), methanol and ethanol. The primary goal of this study is to investigate the fundamental chemical reactions occurring during plasma-assisted reforming of liquid hydrocarbons and alcohols using streamer-like pulsed electrical discharges. Due to the relatively unexplored field of chemical reactions in liquid plasmas, the focus of this study is on elucidating chemical pathways responsible for the formation of hydrogen, syngas, and other products during the direct reforming of liquid methanol, glycerol, and pentane as model species.

  3. Tunable photonic bandgap fiber based devices for optical networks

    DEFF Research Database (Denmark)

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

    2005-01-01

    , for example a liquid crystal that changes optical properties when subjected to, for example, an optical or an electrical field. The utilization of these two basic properties allows design of tunable optical devices for optical networks. In this work, we focus on applications of such devices and discuss recent...

  4. Realization of an Electrically Tunable Narrow-Bandwidth Atomically Thin Mirror Using Monolayer MoSe2

    Science.gov (United States)

    Back, Patrick; Zeytinoglu, Sina; Ijaz, Aroosa; Kroner, Martin; Imamoǧlu, Atac

    2018-01-01

    The advent of two-dimensional semiconductors, such as van der Waals heterostructures, propels new research directions in condensed matter physics and enables development of novel devices with unique functionalities. Here, we show experimentally that a monolayer of MoSe2 embedded in a charge controlled heterostructure can be used to realize an electrically tunable atomically thin mirror, which effects 87% extinction of an incident field that is resonant with its exciton transition. The corresponding maximum reflection coefficient of 41% is only limited by the ratio of the radiative decay rate to the nonradiative linewidth of exciton transition and is independent of incident light intensity up to 400 W /cm2 . We demonstrate that the reflectivity of the mirror can be drastically modified by applying a gate voltage that modifies the monolayer charge density. Our findings could find applications ranging from fast programable spatial light modulators to suspended ultralight mirrors for optomechanical devices.

  5. Enhanced quantitative phase imaging in self-interference digital holographic microscopy using an electrically focus tunable lens.

    Science.gov (United States)

    Schubert, Robin; Vollmer, Angelika; Ketelhut, Steffi; Kemper, Björn

    2014-12-01

    Self-interference digital holographic microscopy (DHM) has been found particular suitable for simplified quantitative phase imaging of living cells. However, a main drawback of the self-interference DHM principle are scattering patterns that are induced by the coherent nature of the laser light which affect the resolution for detection of optical path length changes. We present a simple and efficient technique for the reduction of coherent disturbances in quantitative phase images. Therefore, amplitude and phase of the sample illumination are modulated by an electrically focus tunable lens. The proposed method is in particular convenient with the self-interference DHM concept. Results from the characterization of the method show that a reduction of coherence induced disturbances up to 70 percent can be achieved. Finally, the performance for enhanced quantitative imaging of living cells is demonstrated.

  6. Mechanically stacked 1-nm-thick carbon nanosheets: ultrathin layered materials with tunable optical, chemical, and electrical properties.

    Science.gov (United States)

    Nottbohm, Christoph T; Turchanin, Andrey; Beyer, André; Stosch, Rainer; Gölzhäuser, Armin

    2011-04-04

    Carbon nanosheets are mechanically stable, free-standing two-dimensional materials with a thickness of ≈1 nm and well defined physical and chemical properties. They are made by radiation-induced cross-linking of aromatic self-assembled monolayers. Herein, a route is presented to the scalable fabrication of multilayer nanosheets with tunable electrical, optical, and chemical properties on insulating substrates. Stacks of up to five nanosheets with sizes of ≈1 cm(2) on oxidized silicon are studied. Their optical characteristics are investigated by visual inspection, optical microscopy, UV-vis reflection spectroscopy, and model calculations. Their chemical composition is studied by X-ray photoelectron spectroscopy. The multilayer samples are then annealed in an ultrahigh vacuum at various temperatures up to 1100 K. A subsequent investigation by Raman, X-ray photoelectron, and UV-vis reflection spectroscopy, as well as by electrical four-point probe measurements, demonstrates that the layered nanosheets transform into nanocrystalline graphene. This structural and chemical transformation is accompanied by changes in the optical properties and electrical conductivity and opens up a new path for the fabrication of ultrathin functional conductive coatings. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

    Science.gov (United States)

    Hou, Xu; Hu, Yuhang; Grinthal, Alison; Khan, Mughees; Aizenberg, Joanna

    2015-03-01

    Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems. But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling is nearly inevitable. Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold--the pressure needed to open the pores--can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas-liquid sorting in a microfluidic flow and to separate a three-phase air-water-oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.

  8. Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Hou, X; Hu, YH; Grinthal, A; Khan, M; Aizenberg, J

    2015-03-04

    Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems(1-10). But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries(6,11-17), a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling is nearly inevitable(11,12). Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold-the pressure needed to open the pores-can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas-liquid sorting in a microfluidic flow and to separate a three-phase air-water-oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.

  9. Exceptionally High Electric Double Layer Capacitances of Oligomeric Ionic Liquids.

    Science.gov (United States)

    Matsumoto, Michio; Shimizu, Sunao; Sotoike, Rina; Watanabe, Masayoshi; Iwasa, Yoshihiro; Itoh, Yoshimitsu; Aida, Takuzo

    2017-11-15

    Electric double layer (EDL) capacitors are promising as next-generation energy accumulators if their capacitances and operation voltages are both high. However, only few electrolytes can simultaneously fulfill these two requisites. Here we report that an oligomeric ionic liquid such as IL4 TFSI with four imidazolium ion units in its structure provides a wide electrochemical window of ∼5.0 V, similar to monomeric ionic liquids. Furthermore, electrochemical impedance measurements using Au working electrodes demonstrated that IL4 TFSI exhibits an exceptionally high EDL capacitance of ∼66 μF/cm 2 , which is ∼6 times as high as those of monomeric ionic liquids so far reported. We also found that an EDL-based field effect transistor (FET) using IL4 TFSI as a gate dielectric material and SrTiO 3 as a channel material displays a very sharp transfer curve with an enhanced carrier accumulation capability of ∼64 μF/cm 2 , as determined by Hall-effect measurements.

  10. Influence of liquid crystalline phases on the tunability of a random laser

    Science.gov (United States)

    Trull, José; Salud, Josep; Diez-Berart, Sergio; López, David O.

    2017-05-01

    In this paper, we report the temperature behavior of an optimized disordered photonic system-based liquid crystal by means of heat capacity and refractive index measurements. The scattering system is formed by a porous borosilicate glass random matrix (about 60%) infiltrated with a smectogenic liquid crystal (about 16%) and a small amount of laser dye (0.1%). The rest of the scattering system is about 24% air, giving rise to a high refractive index contrast scattering system. Such a system has the functionality to change the refractive index contrast with temperature due to the liquid crystal temperature behavior. The system, optically pumped by the second harmonic of a Q -switched Nd:YAG pulsed laser working at 532 nm, exhibits random laser action, the threshold of which depends upon the liquid crystalline mesophase. Temperatures of existence of the smectic-B phase correspond to the most optimized random laser. In such a mesophase, the transport mean free path has been determined as about 16 μm in a coherent backscattering experiment.

  11. Tunable amphiphilicity and multifunctional applications of ionic-liquid-modified carbon quantum dots.

    Science.gov (United States)

    Wang, Baogang; Song, Aixin; Feng, Lei; Ruan, Hong; Li, Hongguang; Dong, Shuli; Hao, Jingcheng

    2015-04-01

    During the past decade, increasing attention has been paid to photoluminescent nanocarbon materials, namely, carbon quantum dots (CQDs). It is gradually accepted that surface engineering plays a key role in regulating the properties and hence the applications of the CQDs. In this paper, we prepared highly charged CQDs through a one-pot pyrolysis with citric acid as carbon source and a room-temperature imidazolium-based ionic liquid as capping agent. The as-prepared CQDs exhibit high quantum yields up to 25.1% and are stable under various environments. In addition, the amphiphilicity of the CQDs can be facilely tuned by anion exchange, which leads to a spontaneous phase transfer between water and oil phase. The promising applications of the CQDs as ion sensors and fluorescent inks have been demonstrated. In both cases, these ionic-liquid-modified CQDs were found to possess novel characteristics and/or superior functions compared to existing ones.

  12. Analysis of holographic polymer-dispersed liquid crystals (HPDLCs) for tunable low frequency diffractive optical elements recording

    Science.gov (United States)

    Fernández, R.; Gallego, S.; Márquez, A.; Francés, J.; Martínez, F. J.; Pascual, I.; Beléndez, A.

    2018-02-01

    Holographic polymer dispersed liquid crystals (HPDLCs) are the result of the optimization of the photopolymer fabrication techniques. They are made by recording in a photopolymerization induced phase separation process (PIPS) in which the liquid crystal molecules diffuse to dark zones in the diffraction grating originated. Thanks to the addition of liquid crystal molecules to the composition, this material has a dynamic behavior by reorientation of the liquid crystal molecules applying an electrical field. In this sense, it is possible to use this material to make dynamic devices. In this work, we study the behavior of this material working in low frequencies with different spatial periods of blazed gratings, a sharp profile whose recording is possible thanks to the addition of a Holoeye LCoS-Pluto spatial light modulator with a resolution of 1920 × 1080 pixels (HD) and a pixel size of 8 × 8 μm2. This device allows us to have an accurate and dynamic control of the phase and amplitude of the recording beam.

  13. Tunable bandgap in few-layer black phosphorus by electrical field

    Science.gov (United States)

    Li, Dong; Xu, Jin-Rong; Ba, Kun; Xuan, Ningning; Chen, Mingyuan; Sun, Zhengzong; Zhang, Yu-Zhong; Zhang, Zengxing

    2017-09-01

    Dynamically engineering bandgap in semiconductors may enable a flexible design and optimization of electronics and optoelectronics. Layered black phosphorus is a 2D semiconductor with a direct bandgap and promising device characteristics. Theoretical studies indicate that the bandgap in black phosphorus can be tuned by electrical field. Here, through designing a double-gated field-effect transistor device configuration, we experimentally demonstrate that the bandgap in few-layer black phosphorus can be dynamically continually tuned by perpendicular electrical field. With an electrical displacement field of 1 V nm-1, the detailed study indicates that the bandgap can reduce around 100 meV. The finding here should be helpful on the flexible design and optimization of black phosphorus electronics and optoelectronics, and may open up some other new possible applications.

  14. Anomalous Sequence of Quantum Hall Liquids Revealing a Tunable Lifshitz Transition in Bilayer Graphene

    Science.gov (United States)

    Varlet, Anastasia; Bischoff, Dominik; Simonet, Pauline; Watanabe, Kenji; Taniguchi, Takashi; Ihn, Thomas; Ensslin, Klaus; Mucha-Kruczyński, Marcin; Fal'ko, Vladimir I.

    2014-09-01

    Bilayer graphene is a unique system where both the Fermi energy and the low-energy electron dispersion can be tuned. This is brought about by an interplay between trigonal warping and the band gap opened by a transverse electric field. Here, we drive the Lifshitz transition in bilayer graphene to experimentally controllable carrier densities by applying a large transverse electric field to a h-BN-encapsulated bilayer graphene structure. We perform magnetotransport measurements and investigate the different degeneracies in the Landau level spectrum. At low magnetic fields, the observation of filling factors -3 and -6 quantum Hall states reflects the existence of three maxima at the top of the valence-band dispersion. At high magnetic fields, all integer quantum Hall states are observed, indicating that deeper in the valence band the constant energy contours are singly connected. The fact that we observe ferromagnetic quantum Hall states at odd-integer filling factors testifies to the high quality of our sample. This enables us to identify several phase transitions between correlated quantum Hall states at intermediate magnetic fields, in agreement with the calculated evolution of the Landau level spectrum. The observed evolution of the degeneracies, therefore, reveals the presence of a Lifshitz transition in our system.

  15. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Zervos, M., E-mail: zervos@ucy.ac.cy; Giapintzakis, J. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Mihailescu, C. N. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Luculescu, C. R. [Department of Mechanical and Manufacturing Engineering, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); National Institute for Laser, Plasma and Radiation Physics, Str. Atomistilor, P.O. Box MG-36, 077125 Magurele (Romania); Florini, N.; Komninou, Ph.; Kioseoglou, J. [Nanostructured Materials Microscopy Group (NMMG), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Othonos, A. [Nanotechnology Research Centre (NRC), University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus); Research Center of Ultrafast Science, Department of Physics, University of Cyprus, P.O. Box 20537, Nicosia 1678 (Cyprus)

    2014-05-01

    Indium tin oxide nanowires were grown by the reaction of In and Sn with O{sub 2} at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In{sub 2}O{sub 3} nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO{sub 2} and suppression of In{sub 2}O{sub 3} permitting compositional and structural tuning from SnO{sub 2} to In{sub 2}O{sub 3} which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  16. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Science.gov (United States)

    Zervos, M.; Mihailescu, C. N.; Giapintzakis, J.; Luculescu, C. R.; Florini, N.; Komninou, Ph.; Kioseoglou, J.; Othonos, A.

    2014-05-01

    Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  17. Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism

    Directory of Open Access Journals (Sweden)

    M. Zervos

    2014-05-01

    Full Text Available Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001. We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.

  18. Tunable fly's-eye lens made of patterned polymer-dispersed liquid crystal.

    Science.gov (United States)

    Liu, Y J; Sun, X W; Shum, P; Yin, X J

    2006-06-12

    A fly's-eye lens was fabricated using polymer-dispersed liquid crystals and its optical properties were evaluated. The morphologies were examined under an optical microscope. The forming process has been simulated based on a patterned photo-polymerization technique in which the spatially modulated reaction rate has been coupled with the time-dependent Ginzburg-Landau (TDGL) equations with the free energies relating to isotropic mixing, nematic ordering, and network elasticity incorporated. The simulated results are in good agreement with the experimental results. The beam profile was tested using a CCD. The results showed that this fly's-eye lens could modulate a Gaussian beam into a mesa-like beam. Such device is potentially useful in beam shaping and many illumination systems that require uniform beam profile.

  19. Liquid-core nanocellulose-shell capsules with tunable oxygen permeability.

    Science.gov (United States)

    Svagan, A J; Bender Koch, C; Hedenqvist, M S; Nilsson, F; Glasser, G; Baluschev, S; Andersen, M L

    2016-01-20

    Encapsulation of oxygen sensitive components is important in several areas, including those in the food and pharmaceutical sectors, in order to improve shelf-life (oxidation resistance). Neat nanocellulose films demonstrate outstanding oxygen barrier properties, and thus nanocellulose-based capsules are interesting from the perspective of enhanced protection from oxygen. Herein, two types of nanocellulose-based capsules with liquid hexadecane cores were successfully prepared; a primary nanocellulose polyurea-urethane capsule (diameter: 1.66 μm) and a bigger aggregate capsule (diameter: 8.3 μm) containing several primary capsules in a nanocellulose matrix. To quantify oxygen permeation through the capsule walls, an oxygen-sensitive spin probe was dissolved within the liquid hexadecane core, allowing non-invasive measurements (spin-probe oximetry, electron spin resonance, ESR) of the oxygen concentration within the core. It was observed that the oxygen uptake rate was significantly reduced for both capsule types compared to a neat hexadecane solution containing the spin-probe, i.e. the slope of the non-steady state part of the ESR-curve was approximately one-third and one-ninth for the primary nanocellulose capsule and aggregated capsule, respectively, compared to that for the hexadecane sample. The transport of oxygen was modeled mathematically and by fitting to the experimental data, the oxygen diffusion coefficients of the capsule wall was determined. These values were, however, lower than expected and one plausible reason for this was that the ESR-technique underestimate the true oxygen uptake rate in the present systems at non-steady conditions, when the overall diffusion of oxygen was very slow. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Electrically tunable multiple Dirac cones in thin films of the (LaO)2(SbSe2)2 family of materials.

    Science.gov (United States)

    Dong, Xiao-Yu; Wang, Jian-Feng; Zhang, Rui-Xing; Duan, Wen-Hui; Zhu, Bang-Fen; Sofo, Jorge O; Liu, Chao-Xing

    2015-10-13

    Two-dimensional Dirac physics has aroused great interests in condensed matter physics ever since the discovery of graphene and topological insulators. The ability to control the properties of Dirac cones, such as bandgap and Fermi velocity, is essential for various new phenomena and the next-generation electronic devices. On the basis of first-principles calculations and an analytical effective model, we propose a new Dirac system with eight Dirac cones in thin films of the (LaO)2(SbSe2)2 family of materials, which has the advantage in its tunability: the existence of gapless Dirac cones, their positions, Fermi velocities and anisotropy all can be controlled by an experimentally feasible electric field. We identify layer-dependent spin texture induced by spin-orbit coupling as the underlying physical reason for electrical tunability of this system. Furthermore, the electrically tunable quantum anomalous Hall effect with a high Chern number can be realized by introducing magnetization into this system.

  1. Giant electric field tunable magnetic properties in a Co50Fe50/lead magnesium niobate-lead titanate multiferroic heterostructure

    Science.gov (United States)

    Yang, Wei-Gang; Morley, Nicola A.; Sharp, Joanne; Rainforth, W. Mark

    2015-08-01

    Co50Fe50/(0 1 1)-oriented lead magnesium niobate-lead titanate (PMN-PT) multiferroic (MF) heterostructures were fabricated by RF sputtering magnetic films onto PMN-PT substrates. The effect of magnetic layer thickness (30 nm to 100 nm) on the magnetoelectric (ME) coupling in the heterostructures was studied independently, due to the almost constant magnetostriction constant (λ = 40   ±   5 ppm) and similar as-grown magnetic anisotropies for all studied magnetic layer thicknesses. A record high remanence ratio (M r/M s) tunability of 95% has been demonstrated in the 65 nm Co50Fe50/PMN-PT heterostructure, corresponding to a large ME constant (α) of 2.5   ×   10-6 s m-1, when an external electric field (E-field) of 9 kV cm-1 was applied. Such an MF heterostructure provides considerable opportunities for E-field-controlled multifunctional devices.

  2. Interdigitated electrode-induced phase grating with an electrically switchable and tunable period.

    Science.gov (United States)

    Kulishov, M

    1999-12-20

    A new design for an adjustable electro-optic phase grating inside a waveguide is proposed. The electric field and the refractive-index distribution induced inside a waveguide by voltage applied to double-sided periodic interdigitated electrode arrays are calculated rigorously on the basis of an original analytical technique. The modeling was carried out with the Mathcad software. It is shown that the fundamental periodicity of the induced grating inside the waveguide can be switched between l and 2l by application of the appropriate voltage, where l is the spatial periodicity of the interdigitated electrodes. One can also fine tune the peak grating reflectivity by changing the constant component of the induced refractive index with the help of the constant component of the electric field inside the waveguide. The suggested design can be used as a basic idea for a variety of optical communication networking applications, including switching, modulation, deflection, and data processing.

  3. Electrically tunable terahertz wave modulator based on complementary metamaterial and graphene

    Energy Technology Data Exchange (ETDEWEB)

    He, Xun-jun, E-mail: hexunjun@hrbust.edu.cn; Li, Teng-yue; Wang, Lei; Wang, Jian-min; Jiang, Jiu-xing [Department of Electronic Science and technology, School of Applied Sciences, Harbin University of Science and Technology, Harbin 150080 (China); Yang, Guo-hui; Meng, Fan-yi; Wu, Qun [Department of Electronic and Communications Engineering, School of Electronic Information Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-05-07

    In this paper, we design and numerically demonstrate an electrically controllable light-matter interaction in a hybrid material/metamaterial system consisting of an artificially constructed cross cut-wire complementary metamaterial and an atomically thin graphene layer to realize terahertz (THz) wave modulator. By applying a bias voltage between the metamaterial and the graphene layer, this modulator can dynamically control the amplitude and phase of the transmitted wave near 1.43 THz. Moreover, the distributions of current density show that this large modulation depth can be attributed to the resonant electric field parallel to the graphene sheet. Therefore, the modulator performance indicates the enormous potential of graphene for developing sophisticated THz communication systems.

  4. Interdigitated Electrode-Induced Phase Grating with an Electrically Switchable and Tunable Period

    Science.gov (United States)

    Kulishov, Mykola

    1999-12-01

    A new design for an adjustable electro-optic phase grating inside a waveguide is proposed. The electric field and the refractive-index distribution induced inside a waveguide by voltage applied to double-sided periodic interdigitated electrode arrays are calculated rigorously on the basis of an original analytical technique. The modeling was carried out with the Mathcad software. It is shown that the fundamental periodicity of the induced grating inside the waveguide can be switched between l and 2 l by application of the appropriate voltage, where l is the spatial periodicity of the interdigitated electrodes. One can also fine tune the peak grating reflectivity by changing the constant component of the induced refractive index with the help of the constant component of the electric field inside the waveguide. The suggested design can be used as a basic idea for a variety of optical communication networking applications, including switching, modulation, deflection, and data processing.

  5. Tunable superlattice amplifiers based on dynamics of miniband electrons in electric and magnetic fields

    OpenAIRE

    Hyart, T. (Timo)

    2009-01-01

    Abstract The most important paradigms in quantum mechanics are probably a twolevel system, a harmonic oscillator and an ideal (infinite) periodic potential. The first two provide a starting point for understanding the phenomena in systems where the spectrum of energy levels is discrete, whereas the last one results in continuous energy bands. Here an attempt is made to study the dynamics of the electrons in a narrow miniband of a semiconductor superlattice under electric and magnetic field...

  6. Electrically tunable transport in antiferromagnetic Sr3Ir2O7

    Science.gov (United States)

    Seinige, Heidi; Wang, Cheng; Cao, Gang; Zhou, Jianshi-S.; Goodenough, John B.; Tsoi, Maxim

    Recently we demonstrated experimentally the existence of interconnections between magnetic state and transport currents in antiferromagnetic (AFM) Mott insulator Sr2IrO4. We found a very large anisotropic magnetoresistance and demonstrated a reversible resistive switching driven by high-density currents/high electric fields. These results support the feasibility of AFM spintronics, where antiferromagnets are used in place of ferromagnets, however a low Néel temperature of this material (240 K) questions any practical applications. Here we present a comparative electrical transport study of its sister compound Sr2IrO4 which has a higher transition temperature (285 K). Similar to the case of Sr2IrO4, we find a continuous reduction in the resistivity of Sr3Ir2O7 as a function of increasing electrical bias and abrupt reversible changes above a threshold bias current. We explain these results by a reduction of activation energy associated with a field-driven lattice distortion. This work was supported in part by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA, and by NSF Grants DMR-1207577, DMR-1265162, and DMR-1122603.

  7. Extraction of DNA by magnetic ionic liquids: tunable solvents for rapid and selective DNA analysis.

    Science.gov (United States)

    Clark, Kevin D; Nacham, Omprakash; Yu, Honglian; Li, Tianhao; Yamsek, Melissa M; Ronning, Donald R; Anderson, Jared L

    2015-02-03

    DNA extraction represents a significant bottleneck in nucleic acid analysis. In this study, hydrophobic magnetic ionic liquids (MILs) were synthesized and employed as solvents for the rapid and efficient extraction of DNA from aqueous solution. The DNA-enriched microdroplets were manipulated by application of a magnetic field. The three MILs examined in this study exhibited unique DNA extraction capabilities when applied toward a variety of DNA samples and matrices. High extraction efficiencies were obtained for smaller single-stranded and double-stranded DNA using the benzyltrioctylammonium bromotrichloroferrate(III) ([(C8)3BnN(+)][FeCl3Br(-)]) MIL, while the dicationic 1,12-di(3-hexadecylbenzimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide bromotrichloroferrate(III) ([(C16BnIM)2C12(2+)][NTf2(-), FeCl3Br(-)]) MIL produced higher extraction efficiencies for larger DNA molecules. The MIL-based method was also employed for the extraction of DNA from a complex matrix containing albumin, revealing a competitive extraction behavior for the trihexyl(tetradecyl)phosphonium tetrachloroferrate(III) ([P6,6,6,14(+)][FeCl4(-)]) MIL in contrast to the [(C8)3BnN(+)][FeCl3Br(-)] MIL, which resulted in significantly less coextraction of albumin. The MIL-DNA method was employed for the extraction of plasmid DNA from bacterial cell lysate. DNA of sufficient quality and quantity for polymerase chain reaction (PCR) amplification was recovered from the MIL extraction phase, demonstrating the feasibility of MIL-based DNA sample preparation prior to downstream analysis.

  8. 30 CFR 57.4130 - Surface electric substations and liquid storage facilities.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Surface electric substations and liquid storage... accumulate within 25 feet of the following: (1) Electric substations. (2) Unburied, flammable or combustible... NONMETAL MINES Fire Prevention and Control Prohibitions/precautions/housekeeping § 57.4130 Surface electric...

  9. 30 CFR 56.4130 - Electric substations and liquid storage facilities.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric substations and liquid storage... MINES Fire Prevention and Control Prohibitions/precautions/housekeeping § 56.4130 Electric substations... shall be stored or allowed to accumulate within 25 feet of the following: (1) Electric substations. (2...

  10. Electrically tunable single-dot nanocavities in the weak and strong coupling regimes

    DEFF Research Database (Denmark)

    Laucht, Arne; Hofbauer, Felix; Angele, Jacob

    2008-01-01

    was varied by changing the lattice temperature [2,3], or by the adsorption of inert-gases at low temperatures [4], we demonstrate that the quantum confined Stark effect can be employed to quickly and reversibly switch the dot-cavity coupling, simply by varying a gate voltage [1]. Our results show...... of the emitted photons from a single-dot nanocavity in the weak and strong coupling regimes. New information is obtained on the nature of the dot-cavity coupling in the weak coupling regime and electrical control of zero dimensional polaritons is demonstrated for the first time. Vacuum Rabi splittings up to 2g...

  11. Electrically tunable transport and resistive switching in doped Ca2RuO4

    Science.gov (United States)

    Shen, Shida; Williamson, Morgan; Cao, Gang; Zhou, Jianshi; Goodenough, John; Tsoi, Maxim

    We study electronic transport properties of Cr doped (2.5%) Mott insulator Ca2RuO4 where electric fields were previously found to induce an insulator-to-metal switching with potential industrial applications. In our experiments we observe a continuous reduction in the resistivity of Ca2RuO4 as a function of increasing electrical bias followed by an abrupt switching at higher biases. Interestingly, the observed switching is non-destructive and requires opposite bias polarities to switch from high-to-low and low-to-high resistance states. Combination of 2-, 3-, and 4-probe measurements provide a means to shed light on the origin of the switching and distinguish between its bulk and interfacial contributions. This work was supported in part by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA, by NSF Grants DMR-1600057, DMR-1265162, and DMR-1122603, and by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2015-CRG4-2626.

  12. Spatial and electrical switching of defect modes in a photonic bandgap device with a polymer-dispersed liquid crystal defect layer.

    Science.gov (United States)

    Wu, Po-Chang; Yeh, En-Rong; Zyryanov, Victor Ya; Lee, Wei

    2014-08-25

    This paper investigates the spectral properties of a one-dimensional photonic crystal (PC) containing an inhomogeneous polymer- dispersed liquid crystal (PDLC) as a defect layer. Experimental results indicate that the voltage-induced reorientation of LC molecules between the light-scattering and transparent states in the PDLC enables the electrical tuning of the transmittance of defect-mode peaks in the spectrum of the PC/PDLC cell. Specifically, owing to the unique configuration of the spatial distribution of LC droplet sizes in the defect layer, a concept concerning the spatial switching in the wavelength of defect modes is proposed. As a result, the PC/PDLC hybrid cell is suggested as a potential element for realizing an electrically tunable and spatially switchable photonic bandgap device, which is polarizer-free and requires no alignment layers in the fabrication process.

  13. Electrically induced reorganization phenomena of liquid metal film printed on biological skin

    Science.gov (United States)

    Guo, Cangran; Yi, Liting; Yu, Yang; Liu, Jing

    2016-12-01

    Liquid metal has been demonstrated to be directly printable on biological skin as physiological measurement elements. However, many fundamental issues remained unclear so far. Here, we disclosed an intriguing phenomenon of electrically induced reorganization of liquid metal film. According to the experiments, when applying an external electric field to liquid metal films which were spray printed on biological skin, it would induce unexpected transformations of the liquid metals among different morphologies and configurations. These include shape shift from a large liquid metal film into a tiny sphere and contraction of liquid metal pool into spherical one. For comprehensively understanding the issues, the impacts of the size, voltage, orientations of the liquid metal electrodes, etc., were clarified. Further, effects of various substrates such as in vitro skin and in vivo skin affecting the liquid metal transformations were experimentally investigated. Compared to the intact tissues, the contraction magnitude of the liquid metal electrode appears weaker on in vivo skin of nude mice under the same electric field. The mechanisms lying behind such phenomena were interpreted through theoretical modeling. Lastly, typical applications of applying the current effect into practical elements such as electrical gating devices were also illustrated as an example. The present findings have both fundamental and practical values, which would help design future technical strategies in fabricating electronically controlled liquid metal electronics on skin.

  14. Electrically tunable sign of capacitance in planar W-doped vanadium dioxide micro-switches

    Directory of Open Access Journals (Sweden)

    Mohammed Soltani, Mohamed Chaker and Joelle Margot

    2011-01-01

    Full Text Available Negative capacitance (NC in a planar W-doped VO2 micro-switch was observed at room temperature in the low-frequency range 1 kHz–10 MHz. The capacitance changed from positive to negative values as the W-doped VO2 active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance–voltage hysteresis was observed as the applied voltage was cycled from −35 to 35 V. These observations suggest that NC results from the increase of the electrically induced conductivity in the active layer. This NC phenomenon could be exploited in advanced multifunctional devices including ultrafast switches, field-effect transistors and memcapacitive systems.

  15. Tunable SnO2 Nanoribbon by Electric Fields and Hydrogen Passivation

    Directory of Open Access Journals (Sweden)

    Xin-Lian Chen

    2017-01-01

    Full Text Available Under external transverse electronic fields and hydrogen passivation, the electronic structure and band gap of tin dioxide nanoribbons (SnO2NRs with both zigzag and armchair shaped edges are studied by using the first-principles projector augmented wave (PAW potential with the density function theory (DFT framework. The results showed that the electronic structures of zigzag and armchair edge SnO2NRs exhibit an indirect semiconducting nature and the band gaps demonstrate a remarkable reduction with the increase of external transverse electronic field intensity, which demonstrate a giant Stark effect. The value of the critical electric field for bare Z-SnO2NRs is smaller than A-SnO2NRs. In addition, the different hydrogen passivation nanoribbons (Z-SnO2NRs-2H and A-SnO2NRs-OH show different band gaps and a slightly weaker Stark effect. The band gap of A-SnO2NRs-OH obviously is enhanced while the Z-SnO2NRs-2H reduce. Interestingly, the Z-SnO2NRs-OH presented the convert of metal-semiconductor-metal under external transverse electronic fields. In the end, the electronic transport properties of the different edges SnO2NRs are studied. These findings provide useful ways in nanomaterial design and band engineering for spintronics.

  16. Investigation of surface charge density on solid-liquid interfaces by modulating the electrical double layer.

    Science.gov (United States)

    Moon, Jong Kyun; Song, Myung Won; Pak, Hyuk Kyu

    2015-05-20

    A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid-liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid-liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a dc bias voltage across the plates, an ac electric current can be generated. By measuring the voltage drop across a load resistor as a function of bias voltage, we can study the surface charge density on solid-liquid interfaces. Our experimental results agree very well with the simple equivalent electrical circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. We expect this method to aid in the study of electrical phenomena on solid-liquid interfaces.

  17. Ultrathin optical switch based on a liquid crystal/silver nanoparticles mixture as a tunable indefinite medium

    CERN Document Server

    Spinozzi, Elisa

    2011-01-01

    We predict that a liquid crystal/silver nanoparticles mixture can be designed so that, in a frequency range, its effective ordinary and extraordinary permittivities have real parts of different signs. We exploit this result to design a nano-photonic device obtained by sandwiching a few hundred nanometer thick slab of the proposed mixture between two silica layers. By resorting to full-wave simulations, we show that, by varying the direction of an externally applied electric field, the device can be used as an optical modulator since its transmissivity can be switched between 0.02 and 0.4 at a wavelength close to the frequency range where the medium is indefinite. The device functionality physically stems from the fact the orientation of the hyperbola characterizing extraordinary waves within the indefinite medium follows the applied electric field direction and therefore, if the hyperbola asymptote is nearly normal to the slab, full switch between evanescent and homogeneous propagating waves can be achieved w...

  18. Electrically and mechanically induced long period gratings in liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Scolari, Lara; Lægsgaard, Jesper

    2007-01-01

    We demonstrate electrically and mechanically induced long period gratings (LPGs) in a photonic crystal fiber (PCF) filled with a highindex liquid crystal. The presence of the liquid crystal changes the guiding properties of the fiber from an index guiding fiber to a photonic bandgap guiding fiber...

  19. Electric field fluctuations in liquid tellurium alloys a hint to bond character

    NARCIS (Netherlands)

    Paulick, C.A.; Brinkmann, R.; Elwenspoek, Michael Curt; von Hartrott, M.; Kiehl, M.; Maxim, P.; Quitmann, D.

    1985-01-01

    Atomic scale electric field fluctuations in liquid tellurium alloys are detected as they induce nuclear spin relaxation rate RQ in noble gas impurity atoms, via quadrupolar interaction. Results for Xe in liquid Ag, Ga, In, Tl, Ge, Sn---Te alloys are discussed, assuming that bonding in these alloys

  20. Electric pulse resistance of liquid nitrogen and rubber

    Science.gov (United States)

    Kurets, V. I.; Tarakanovskii, É. N.; Filatov, G. P.

    1995-05-01

    We report the results of experimental investigations of the breakdown amplitudes of pulsed voltages applied to centimeter-thick layers of liquid nitrogen and various kinds of rubber at 77 K. We report the characteristics of pulses that will puncture rubber in liquid nitrogen.

  1. Liquid Crystal Photonic bandgap Fibers: Modeling and Devices

    DEFF Research Database (Denmark)

    Weirich, Johannes

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

  2. Near-wall molecular ordering of dilute ionic liquids

    NARCIS (Netherlands)

    Jitvisate, Monchai; Seddon, James Richard Thorley

    2017-01-01

    The interfacial behavior of ionic liquids promises tunable lubrication as well as playing an integral role in ion diffusion for electron transfer. Diluting the ionic liquids optimizes bulk parameters, such as electric conductivity, and one would expect dilution to disrupt the near-wall molecular

  3. Tunable femtosecond Cherenkov fiber laser

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper

    2014-01-01

    We demonstrate electrically-tunable femtosecond Cherenkov fiber laser output at the visible range. Using an all-fiber, self-starting femtosecond Yb-doped fiber laser as the pump source and nonlinear photonic crystal fiber link as the wave-conversion medium, ultrafast, milliwatt-level, tunable...

  4. Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

    Directory of Open Access Journals (Sweden)

    Amanda García-García

    2016-06-01

    Full Text Available Single-wall carbon nanotubes (SWCNT are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules.

  5. Electro-optical study of chiral nematic liquid crystal/chiral ionic liquid composites with electrically controllable selective reflection characteristics.

    Science.gov (United States)

    Hu, Wang; Zhang, Lipei; Cao, Hui; Song, Li; Zhao, Haiyan; Yang, Zhou; Cheng, Zihui; Yang, Huai; Guo, Lin

    2010-03-20

    A chiral nematic liquid crystal (N*-LC)/chiral ionic liquid (CIL) composite with unique electro-optical characteristics was prepared and filled into a planar treated cell. When an electric field was applied to the cell, the anions and the cations of CIL moved towards the anode and the cathode of the power supply, respectively, thus forming a density gradient of the chiral groups, which resulted in wideband reflection. By adjusting the intensity of the electric field, the reflection bandwidth can be controlled accurately and reversibly. Moreover, the electric field-induced states can be memorized after the applied electric field is turned off. The reflective properties of the composite are investigated in the visible and near-infrared region, respectively. Additionally, the changes of the reflection bandwidths with the intensity and the applied time of the electric field were also investigated. From scanning electron microscopy (SEM) investigations, the mechanism of the electrically controllable reflection was demonstrated. Potential applications of the composite are related to reflective, color electronic paper (E-paper) and smart reflective windows for the solar light management.

  6. Microencapsulation of chemotherapeutics into monodisperse and tunable biodegradable polymers via electrified liquid jets: control of size, shape, and drug release.

    Science.gov (United States)

    Fattahi, Pouria; Borhan, Ali; Abidian, Mohammad Reza

    2013-09-06

    This paper describes microencapsulation of antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, Carmustine) into biodegradable polymer poly(lactic-co-glycolic) acid (PLGA) using an electrojetting technique. The resulting BCNU-loaded PLGA microcapsules have significantly higher drug encapsulation efficiency, more tunable drug loading capacity, and (3) narrower size distribution than those generated using other encapsulation methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Impedance of Polymer-Dispersed Liquid Crystals with Carbon Nanofibers in Weak Electric Fields

    Science.gov (United States)

    Zhdanov, K. R.; Romanenko, A. I.; Zharkova, G. M.; Podyacheva, O. Yu.

    2016-11-01

    Impedance of polymer-dispersed liquid crystals modified by carbon nanofibers is studied in fields lower than the threshold field of the director reorientation of a liquid crystal. It is shown that the real and imaginary parts of the impedance obey to the relationship (Zre - X0)2 + (Zim - Y0)2 = R 0 2 , where X0, Y0, and R0 are the fitting parameters depending on the frequency of the exciting electric field.

  8. Conductor of high electrical current at high temperature in oxygen and liquid metal environment

    Science.gov (United States)

    Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth

    2016-01-12

    In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.

  9. High pressure electrical conductivity in naturally occurring silicate liquids

    Science.gov (United States)

    Tyburczy, James A.; Waff, Harve S.

    Electrical conductivities of molten Hawaiian rhyodacite and Yellowstone rhyolite obsidian were measured between 1200° C and 1400° C and at pressures up to 25 kilobars. The two melts exhibit similar trends. Arrhenius behavior is observed at all pressures studied. Isobaric activation enthalpies increase from about 0.5 eV at atmospheric pressure to about 0.9 eV at 25 kbars, and the magnitude of the conductivity decreases by about a factor of 4 between 0 and 25 kbar. At pressures between about 10 and 15 kbar an abrupt decrease in the slopes of isothermal log a versus pressure plots is observed. In each pressure range an equation of the form σ = σ'0 exp [- (E'σ + PΔV'σ)/kT], where σ'0, E'σ, and ΔV'σ, are constants, describes the polybaric, polythermal data. Comparison of these data with high pressure electrical conductivities of molten basalt and andesite reveals that relatively silica-rich melts, from andesitic to rhyolitic in composition, display similar trends, while the basaltic melt has analogous, but quantitatively different trends. Comparison of zero-pressure electrical conductivity and sodium diffusivity by means of the Nernst-Einstein relation indicates that sodium ion transport is the dominant mechanism of charge transport in the obsidian melt at zero pressure. The tholeiitic melt, on the other hand, displays only order of magnitude agreement between the electrical conductivity and sodium diffusivity, indicating that either ions other than sodium play a significant role in electrical transport or that the motions of the sodium ions are strongly correlated, or both. Comparison of the isobaric and isochoric activation enthalpies indicates that electrical conduction is energy restrained, as opposed to volume restrained. Conductivities in the andesitic, rhyodacitic, and rhyolitic melts conform to a single compensation law line, with no indication of the change in activation volume. The tholeiitic melt has a slightly different compensation line. In light

  10. The Role of Electrical Double Layer Structure in Ionic Liquid Gated Devices.

    Science.gov (United States)

    Black, Jennifer M; Come, Jérémy; Bi, Sheng; Zhu, Mengyang; Zhao, Wei; Wong, Anthony T; Noh, Joo Hyon; Pudasaini, Pushpa R; Zhang, Pengfei; Okatan, Mahmut Baris; Dai, Sheng; Kalinin, Sergei V; Rack, Philip D; Ward, Thomas Zac; Feng, Guang; Balke, Nina

    2017-10-24

    Ionic liquid gating of transition metal oxides has enabled new states (magnetic, electronic, metal-insulator), providing fundamental insights into physics of strongly correlated oxides. However, despite much research activity little is known about the correlation of the structure of the liquids in contact with the transition metal oxide surface, its evolution with the applied electric potential, and its correlation with the measured electronic properties of the oxide. Here, we investigate the structure of an ionic liquid at a semiconducting oxide interface during the operation of a thin film transistor where the electrical double layer gates the device using experiment and theory. We show that the transition between the ON and OFF states of the amorphous indium gallium zinc oxide transistor is accompanied by a densification and preferential spatial orientation of counter-ions at the oxide channel surface. This process occurs in three distinct steps, corresponding to ion orientations and consequently regimes of different electrical conductivity. The reason for this can be found in the surface charge densities on the oxide surface when different ion arrangements are present. Overall, the field effect gating process is elucidated in terms of the interfacial ionic liquid structure and provides unprecedented insight into the working of a liquid gated transistor linking the nanoscopic structure to the functional property. This knowledge will enable both new ionic liquid design as well as advanced device concepts.

  11. Electric-field variations within a nematic-liquid-crystal layer.

    Science.gov (United States)

    Cummings, L J; Mema, E; Cai, C; Kondic, L

    2014-07-01

    A thin layer of nematic liquid crystal (NLC) across which an electric field is applied is a setup of great industrial importance in liquid crystal display devices. There is thus a large literature modeling this situation and related scenarios. A commonly used assumption is that an electric field generated by electrodes at the two bounding surfaces of the layer will produce a field that is uniform: that is, the presence of NLC does not affect the electric field. In this paper, we use calculus of variations to derive the equations coupling the electric potential to the orientation of the NLC's director field, and use a simple one-dimensional model to investigate the limitations of the uniform field assumption in the case of a steady applied field. The extension of the model to the unsteady case is also briefly discussed.

  12. The effect of electric fields upon liquid extraction. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Carleson, T.E.

    1988-04-13

    A series of mass transfer studies were conducted for the extraction of solute from droplets falling in an electric field. The experiments were planned such that the dispersed phase resistance was controlling. In one series of experiments single drops were formed from a charged nozzle and allowed to fall through a continuous, dielectric phase. The drop size and velocity were correlated by means of a simple force balance. Drop mass transfer coefficients were calculated for the drop free fall period and were compared to predictions based upon literature correlations for an oscillating droplet in-the absence of an electric field. Droplet size and velocity were approximately predicted by a staple force balance whereas the mass transfer coefficient was approximately 25--250% higher than that predicted. Droplet extraction efficiencies Increased about 20--30% in the presence of electric fields up to 2 kv/cm. For the same field, the drop diameter decreased 30--50% and the terminal velocity increased by up to 50%. The enhancements for the toluene-water system can be ascribed to increases in terminal velocity and decreases in drop diameter. The mass transfer model for freely falling drops proposed by Skelland and Wellek roughly predicts the moderate mass transfer efficiency increases (about 18% at 1 kv/cm) for the toluene water system but failed to predict the increases (about 25% at 0.5 kv/cm) for the heptane furfural system. The second series of experiments involved the formation of a swarm of droplets In a three stage sieve tray column. In a separate series of experiments. the effect of the electric field upon mass transfer from drops exhibiting interfacial turbulence was evaluated.

  13. The effect of electric fields upon liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Carleson, T.E.

    1988-04-13

    A series of mass transfer studies were conducted for the extraction of solute from droplets falling in an electric field. The experiments were planned such that the dispersed phase resistance was controlling. In one series of experiments single drops were formed from a charged nozzle and allowed to fall through a continuous, dielectric phase. The drop size and velocity were correlated by means of a simple force balance. Drop mass transfer coefficients were calculated for the drop free fall period and were compared to predictions based upon literature correlations for an oscillating droplet in-the absence of an electric field. Droplet size and velocity were approximately predicted by a staple force balance whereas the mass transfer coefficient was approximately 25--250% higher than that predicted. Droplet extraction efficiencies Increased about 20--30% in the presence of electric fields up to 2 kv/cm. For the same field, the drop diameter decreased 30--50% and the terminal velocity increased by up to 50%. The enhancements for the toluene-water system can be ascribed to increases in terminal velocity and decreases in drop diameter. The mass transfer model for freely falling drops proposed by Skelland and Wellek roughly predicts the moderate mass transfer efficiency increases (about 18% at 1 kv/cm) for the toluene water system but failed to predict the increases (about 25% at 0.5 kv/cm) for the heptane furfural system. The second series of experiments involved the formation of a swarm of droplets In a three stage sieve tray column. In a separate series of experiments. the effect of the electric field upon mass transfer from drops exhibiting interfacial turbulence was evaluated.

  14. Calculations of the Electric Fields in Liquid Solutions

    Science.gov (United States)

    Fried, Stephen D.; Wang, Lee-Ping; Boxer, Steven G.; Ren, Pengyu; Pande, Vijay S.

    2014-01-01

    The electric field created by a condensed phase environment is a powerful and convenient descriptor for intermolecular interactions. Not only does it provide a unifying language to compare many different types of interactions, but it also possesses clear connections to experimental observables, such as vibrational Stark effects. We calculate here the electric fields experienced by a vibrational chromophore (the carbonyl group of acetophenone) in an array of solvents of diverse polarities using molecular dynamics simulations with the AMOEBA polarizable force field. The mean and variance of the calculated electric fields correlate well with solvent-induced frequency shifts and band broadening, suggesting Stark effects as the underlying mechanism of these key solution phase spectral effects. Compared to fixed-charge and continuum models, AMOEBA was the only model examined that could describe non-polar, polar, and hydrogen bonding environments in a consistent fashion. Nevertheless, we found that fixed-charge force fields and continuum models were able to replicate some results of the polarizable simulations accurately, allowing us to clearly identify which properties and situations require explicit polarization and/or atomistic representations to be modeled properly, and for which properties and situations simpler models are sufficient. We also discuss the ramifications of these results for modeling electrostatics in complex environments, such as proteins. PMID:24304155

  15. Tunable electro-optic filter stack

    Energy Technology Data Exchange (ETDEWEB)

    Fontecchio, Adam K.; Shriyan, Sameet K.; Bellingham, Alyssa

    2017-09-05

    A holographic polymer dispersed liquid crystal (HPDLC) tunable filter exhibits switching times of no more than 20 microseconds. The HPDLC tunable filter can be utilized in a variety of applications. An HPDLC tunable filter stack can be utilized in a hyperspectral imaging system capable of spectrally multiplexing hyperspectral imaging data acquired while the hyperspectral imaging system is airborne. HPDLC tunable filter stacks can be utilized in high speed switchable optical shielding systems, for example as a coating for a visor or an aircraft canopy. These HPDLC tunable filter stacks can be fabricated using a spin coating apparatus and associated fabrication methods.

  16. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    Science.gov (United States)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  17. Development of a LSSVM-GC model for estimating the electrical conductivity of ionic liquids

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Ilani-Kashkouli, Poorandokht; Sattari, Mehdi

    2014-01-01

    In this communication, an extensive set of 1077 experimental electrical conductivity data for 54 ionic liquids (ILs) was collected from 21 different literature sources. Using this dataset, a reliable least square support vector machine-group contribution (LSSVM-GC) model has been developed, which...... employs a total of 22 sub-structures in addition to the temperature to represent/predict the electrical conductivity of ILs. In order to distinguish the effects of the anion and cation on the electrical conductivity of ILs, 11 sub-structures related to the chemical structure of anions, and 11 sub...

  18. Temperature influence on electrically controlled liquid crystal filled photonic bandgap fiber devices

    DEFF Research Database (Denmark)

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

    2009-01-01

    We experimentally investigate the temperature influence on electrically controlled liquid crystal filled photonic bandgap fiber device. The phase shift in the wavelength range 1520nm-1600nm for realizing quarter and half wave plates at different temperatures by applying a certain voltage...

  19. 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...

  20. Electrical stimulation towards melanoma therapy via liquid metal printed electronics on skin.

    Science.gov (United States)

    Li, Jun; Guo, Cangran; Wang, Zhongshuai; Gao, Kai; Shi, Xudong; Liu, Jing

    2016-12-01

    We proposed a method of using electrical stimulation for treatment of malignant melanoma through directly spray-printing liquid metal on skin as soft electrodes to deliver low intensity, intermediate frequency electric fields. With patterned conductive liquid metal components on mice skin and under assistance of a signal generator, a sine wave electrical power with voltage of 5 V and 300 kHz could be administrated on treating malignant melanoma tumor. The experiments demonstrated that tumor volume was significantly reduced compared with that of the control group. Under the designed parameters (signal: sine wave, signal amplitude Vpp: 5 V and Vpp: 4 V, frequency: 300 kHz) of Tumor treating fields (TTFields) with the sprayed liquid metal electrode, four mice tumor groups became diminishing after 1 week of treatment. The only device-related side effect as seen was a mild to moderate contact dermatitis underneath the field delivering electrodes. The SEM images and pathological analysis demonstrated the targeted treating behavior of the malignant melanoma tumor. Further, thermal infrared imaging experiments indicated that there occur no evident heating effects in the course of treatment. Besides, the liquid metal is easy to remove through medical alcohol. Tumor treating fields through liquid metal electrode could offer a safe, straightforward and effective treatment modality which evidently slows down tumor growth in vivo. These promising results also raised the possibility of applying spray-printing TTFields as an easy going physical way for future cancer therapy.

  1. Electrical control of Faraday rotation at a liquid-liquid interface.

    Science.gov (United States)

    Marinescu, Monica; Kornyshev, Alexei A; Flatté, Michael E

    2015-01-01

    A theory is developed for the Faraday rotation of light from a monolayer of charged magnetic nanoparticles at an electrified liquid-liquid interface. The polarization fields of neighboring nanoparticles enhance the Faraday rotation. At such interfaces, and for realistic sizes and charges of nanoparticles, their adsorption-desorption can be controlled with a voltage variationFaraday rotation. A calculation based on the Maxwell-Garnett theory predicts that the corresponding redistribution of 40 nm nanoparticles of yttrium iron garnet can switch a cavity with a quality factor larger than 10(4) for light of wavelength 500 nm at normal incidence.

  2. Tunable band gap of MoS2-SiC van der Waals heterostructures under normal strain and an external electric field

    Directory of Open Access Journals (Sweden)

    Luo Min

    2017-01-01

    Full Text Available The structure and electronic properties of the MoS2/SiC van der Waals (vdW heterostructures under an influence of normal strain and an external electric field have been investigated by the first-principles method. Our results reveal that the compressive strain has much influence on the band gap of the vdW heterostructures and the band gap monotonically increases from 0.955 to 1.343 eV. The results also imply that electrons are likely to transfer from MoS2 to SiC monolayer due to the deeper potential of SiC monolayer. Interestingly, by applying a vertical external electric field, the results present a parabola-like relationship between the band gap and the strength. As the E-field changes from -0.55 to +0.18 V/Å, the band gap first increases from zero to a maximum of about 1.76 eV and then decreases to zero. The significant variations of band gap are owing to different states of Mo, S, Si, and C atoms in conduction band and valence band. The predicted electric field tunable band gap of the MoS2/SiC vdW heterostructures is very promising for its potential use in nanodevices.

  3. The electrical resistivity of solid and liquid Fe at pressures up to 7 GPa

    Science.gov (United States)

    Secco, R. A.; Schloessin, H. H.

    1989-05-01

    The electrical resistivity of pure solid and liquid Fe has been measured at pressures up to 7 GPa in a large volume cubic anvil press. In conjunction with the four-wired method, a novel technique of potential lead attachment was employed to measure the resistivity of 0.020-in-diameter Fe wire samples. Both the temperature and pressure coefficients of resistivity have been determined for solid and liquid Fe. The temperature coefficients of resistivity (TCR) in the liquid state are of the order of 10-4 K-1 and show an abrupt increase at approximately 5.2 GPa corresponding to the δ-γ-liquid triple point. We have interpreted this discontinuity in the TCR to be a reflection of local atomic structure in the liquid state which is reminiscent of the parent solid structure. By analogy, this result can be applied to the geophysically more important γ-ɛ-liquid triple point. By examining the fundamental effects of pressure and temperature on the density of states function and their ranges we arrive at an estimate of 1.2-1.5 × 10-6 Ωm for the electrical resistivity of pure Fe at the pressures and temperatures expected in the Earth's core.

  4. An investigation for structure transformation in electric pulse modified liquid aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Qi Jingang, E-mail: Qijingang1974@sina.co [School of Material Science and Engineering, Liaoning University of Technology, Jinzhou 121001 (China); Wang Jianzhong; He Lijia; Zhao Zuofu; Du Huiling [School of Material Science and Engineering, Liaoning University of Technology, Jinzhou 121001 (China)

    2011-02-15

    The electric pulse (EP) modification of liquid metal is a novel method for grain refinement. In this work, the structure tests of EP-modified liquid aluminum were conducted and investigated using high-temperature X-ray diffractometer by virtue of the outstanding structural heredity of EP-modified liquid aluminum. The results show that the EP-modified liquid structure tends to be slack and unordered with increasing temperature similar to that of the unmodified. Nevertheless, the quantitative characterization denoted by the liquid structural parameters exhibits its discrepancy. At the modifying temperature of 750 {sup o}C, the order of degree of EP-modified liquid aluminum is remarkably strengthened and the value of average atomic number per cluster changes from 119 (no EP) up to 174 (EP) by an increase of 46%. These tests experimentally testified Wang's electric pulse modification (EPM) model that was built only by phenomenology, and hereby the mechanism of grain refinement resulting from EPM is further elucidated.

  5. Electric field-tunable Ba{sub x}Sr{sub 1-x}TiO{sub 3} films with high figures of merit grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Mikheev, Evgeny; Kajdos, Adam P.; Hauser, Adam J.; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2012-12-17

    We report on the dielectric properties of Ba{sub x}Sr{sub 1-x}TiO{sub 3} (BST) films grown by molecular beam epitaxy on epitaxial Pt bottom electrodes. Paraelectric films (x Less-Than-Or-Equivalent-To 0.5) exhibit dielectric losses that are similar to those of BST single crystals and ceramics. Films with device quality factors greater than 1000 and electric field tunabilities exceeding 1:5 are demonstrated. The results provide evidence for the importance of stoichiometry control and the use of a non-energetic deposition technique for achieving high figures of merit of tunable devices with BST thin films.

  6. Liquid/vapour phase separation in He-4 using electric fields

    Science.gov (United States)

    Israelsson, U. E.; Jackson, H. W.; Petrac, D.

    1988-01-01

    In space, a replacement must be found for gravity to physically control and, in certain instances, contain cryogenic liquids. A program has been started at the Jet Propulsion Laboratory to study the use of electric field generated forces to establish the required orienting effects. Measurements which show that it is possible to apply strong enough electric fields to a liquid/vapor interface of He-4 to obtain an orienting force comparable to gravity are presented. Our measurements span the temperature range 1.7-4.2 K and demonstrate the applicability of Pashen's law for maximum attainable field before breakdown occurs. Some advantages of the electric field separator as opposed to passive surface tension devices are identified.

  7. Synthesis of fullerene nanowhiskers using the liquid-liquid interfacial precipitation method and their mechanical, electrical and superconducting properties

    Science.gov (United States)

    Miyazawa, Kun'ichi

    2015-02-01

    Fullerene nanowhiskers (FNWs) are thin crystalline fibers composed of fullerene molecules, including C60, C70, endohedral, or functionalized fullerenes. FNWs display n-type semiconducting behavior and are used in a diverse range of applications, including field-effect transistors, solar cells, chemical sensors, and photocatalysts. Alkali metal-doped C60 (fullerene) nanowhiskers (C60NWs) exhibit superconducting behavior. Potassium-doped C60NWs have realized the highest superconducting volume fraction of the alkali metal-doped C60 crystals and display a high critical current density (Jc) under a high magnetic field of 50 kOe. The growth control of FNWs is important for their success in practical applications. This paper reviews recent FNWs research focusing on their mechanical, electrical and superconducting properties and growth mechanisms in the liquid-liquid interfacial precipitation method.

  8. Electric field generation of Skyrmion-like structures in a nematic liquid crystal.

    Science.gov (United States)

    Cattaneo, Laura; Kos, Žiga; Savoini, Matteo; Kouwer, Paul; Rowan, Alan; Ravnik, Miha; Muševič, Igor; Rasing, Theo

    2016-01-21

    Skyrmions are particle-like topological objects that are increasingly drawing attention in condensed matter physics, where they are connected to inversion symmetry breaking and chirality. Here we report the generation of stable Skyrmion-like structures in a thin nematic liquid crystal film on chemically patterned patchy surfaces. Using the interplay of material elasticity and surface boundary conditions, we use a strong electric field to quench the nematic liquid crystal from a fully aligned phase to vortex-like nematic liquid crystal structures, centered on patterned patches, which carry two different sorts of topological defects. Numerical calculations reveal that these are Skyrmion-like structures, seeded from the surface boojum topological defects and swirling towards the second confining surface. These observations, supported by numerical methods, demonstrate the possibility to generate, manipulate and study Skyrmion-like objects in nematic liquid crystals on patterned surfaces.

  9. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF).

    Science.gov (United States)

    Meng, Zhaokai; Petrov, Georgi I; Yakovlev, Vladislav V

    2016-02-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm(-1) to 4500 cm(-1), sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies.

  10. N, S co-doped carbon dots with high quantum yield: tunable fluorescence in liquid/solid and extensible applications

    Science.gov (United States)

    Yang, Mei; Meng, Xinlei; Li, Baoyan; Ge, Shusheng; Lu, Yun

    2017-06-01

    A set of the highly fluorescent N, S co-doped carbon dots (NSCDs) were prepared through one-step hydrothermal synthesis at different temperature with citric acid as the carbon source and cysteamine as the N, S source. The NSCDs synthesized at 200 °C show significant quantum yield (81%) due to its optimal structure. The structure of the NSCDs changed with varying degrees of carbonization/aromatization and different content of multifunctional groups of C=O, -NH2, -OH, -SH, and N, S-aromatic heterocycte under different preparation temperatures, thus exhibiting tunable fluorescence. Especially, the obtained NSCDs exhibited a blue fluorescence in solution state and changed from strong blue to yellowish-green in its solid state under UV light as a result of the increase in preparation temperature. The as-prepared NSCDs can be used in selective detection of complex anions such as Cr2O7 2- and Fe(CN)6 3-, cell imaging, and preparation of fluorescent composite films.

  11. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Amanda García-García

    2015-02-01

    Full Text Available The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low.

  12. Cavity ring-down spectroscopy for detection in liquid chromatography: Extension to tunable sources and ultraviolet wavelengths

    NARCIS (Netherlands)

    van der Sneppen, L.; Wiskerke, A.E.; Ariese, F.; Gooijer, C.; Ubachs, W.M.G.

    2006-01-01

    In earlier studies, it was demonstrated that the sensitivity of absorbance detection in liquid chromatography (LC) can be improved significantly by using cavity ring-down spectroscopy (CRDS). Thus far, CRDS experiments have been performed using visible laser light at fixed standard wavelengths, such

  13. Liquid Phase Synthesis of CoP Nanoparticles with High Electrical Conductivity for Advanced Energy Storage

    Directory of Open Access Journals (Sweden)

    Guo-Qun Zhang

    2017-01-01

    Full Text Available Transition metal phosphide alloys possess the metalloid characteristics and superior electrical conductivity and are a kind of high electrical conductive pseudocapacitive materials. Herein, high electrical conductive cobalt phosphide alloys are fabricated through a liquid phase process and a nanoparticles structure with high surface area is obtained. The highest specific capacitance of 286 F g−1 is reached at a current density of 0.5 A g−1. 63.4% of the specific capacitance is retained when the current density increased 16 times and 98.5% of the specific capacitance is maintained after 5000 cycles. The AC//CoP asymmetric supercapacitor also shows a high energy density (21.3 Wh kg−1 and excellent stability (97.8% of the specific capacitance is retained after 5000 cycles. The study provides a new strategy for the construction of high-performance energy storage materials by enhancing their intrinsic electrical conductivity.

  14. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions.

    Science.gov (United States)

    Li, Yi; Wu, Congjun

    2014-12-10

    The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit d(r(2)-3z(2)) anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid (3)He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled (3)He-B phase with J = 0 and the spin-orbit decoupled (3)He-A phase.

  15. Formation of a Crack-Free, Hybrid Skin Layer with Tunable Surface Topography and Improved Gas Permeation Selectivity on Elastomers Using Gel-Liquid Infiltration Polymerization.

    Science.gov (United States)

    Wang, Mengyuan; Gorham, Justin M; Killgore, Jason P; Omidvar, Maryam; Lin, Haiqing; DelRio, Frank W; Cox, Lewis M; Zhang, Zheng; Ding, Yifu

    2017-08-23

    Surface modifications of elastomers and gels are crucial for emerging applications such as soft robotics and flexible electronics, in large part because they provide a platform to control wettability, adhesion, and permeability. Current surface modification methods via ultraviolet-ozone (UVO) and/or O2 plasma, atomic layer deposition (ALD), plasmas deposition, and chemical treatment impart a dense polymer or inorganic layer on the surface that is brittle and easy to fracture at low strain levels. This paper presents a new method, based on gel-liquid infiltration polymerization, to form hybrid skin layers atop elastomers. The method is unique in that it allows for control of the skin layer topography, with tunable feature sizes and aspect ratios as high as 1.8 without fracture. Unlike previous techniques, the skin layer formed here dramatically improves the barrier properties of the elastomer, while preserving skin layer flexibility. Moreover, the method is versatile and likely applicable to most interfacial polymerization systems and network polymers on flat and patterned surfaces.

  16. Soft Anisotropic Conductors as Electric Vias for Ga-Based Liquid Metal Circuits.

    Science.gov (United States)

    Lu, Tong; Wissman, James; Ruthika; Majidi, Carmel

    2015-12-09

    We introduce a method for sealing liquid metal (LM) circuits with soft anisotropic conductors that prevent leaking, while simultaneously allowing for electrical contact with skin and surface mounted electronics. These films are composed of polydimethylsiloxane (PDMS) embedded with vertically aligned columns of ferromagnetic Ag-Ni microparticles. The microparticles are magnetically aligned and support electrical conductivity only through the thickness (z-axis) of the elastomer film. Measurements on 10-40% (by wt) composites show moderate volumetric resistivity (as low as ρ = 0.03 Ω/m) through the thickness and no conductivity between adjacent traces. Functionality is demonstrated with several illustrative applications related to tactile sensing and electronics hardware integration.

  17. Transparent, Superhydrophobic Surface with Varied Surface Tension Responsiveness in Wettability Based on Tunable Porous Silica Structure for Gauging Liquid Surface Tension.

    Science.gov (United States)

    Wang, Yan; Zhu, Yingjie; Zhang, Chunyang; Li, Jun; Guan, Zisheng

    2017-02-01

    Any solid surface can spontaneously exhibit variational wettability toward liquids with varied surface tension (γ). However, this correspondence has seldom been proposed or used on an artificial superhydrophobic surface, which should be more remarkable and peculiar. Herein, we fabricated robust, transparent superhydrophobic surfaces utilizing acid- and base-catalyzed silica (AC- and BC-silica) particles combined with candle soot template for structural construction and the CVD process for chemical modification. Three types of porous silica structures were devised, which presented distinctive surface tension responsiveness in wettability. Interestingly, all types of surfaces (i.e., AC-, AC/BC-, and BC-silica) show high repellence to high surface tension liquid (γ > 35 mN/m), and small differences are observed. With decreasing γ of the ethanol-water mixtures (γ surfaces have an evident decline, but the features of the decreases are fairly different. As γ decreases, the SCA on the AC-silica surface decreases gradually, but the extent of decline becomes larger when γ surface decreases gradually except for γ ≈ 30.81 mN/m, and the SCA undergoes a sharp decline at γ ≈ 30.81 mN/m. The SCA on the AC/BC-silica surface has a similar variation as that of the SCA on the BC-silica surface, but a lower rate of BC-silica particles, e.g., 1/16, 1/8, 1/1 (AC/BC), further diminishes the critical γ values (where a sharp SCA drop occurs) to 30.16, 29.56, and 28.04 mN/m, respectively. The diversity is believed to be ascribed to the structure-induced selectivity of pore infiltration for the liquid. The tunable responsiveness can be generalized to various classes of organic aqueous solutions including methanol, acetic acid, acetone, and N,N-dimethylformamide. Benefiting from this, we can estimate organics concentration of an organic aqueous solution as well as its liquid surface tension by detecting its wettability on all of the diverse superhydrophobic surfaces.

  18. Tunable, Liquid Resistant Tip Enhanced Raman Spectroscopy Probes: Toward Label-Free Nano-Resolved Imaging of Biological Systems.

    Science.gov (United States)

    Scherger, Jacob D; Foster, Mark D

    2017-08-08

    Tip enhanced Raman spectroscopy (TERS) has been established as a powerful, noninvasive technique for chemical identification at the nanoscale. However, difficulties, including the degradation of probes, limit its use in liquid systems. Here TERS probes for studies in aqueous environments have been demonstrated using titanium nitride coatings with an alumina protective layer. The probes show enhancement in signal intensity as high as 380% in liquid measurements, and the probe resonance can be tuned by varying deposition conditions to optimize performance for different laser sources and types of samples. This development of inexpensively produced probes suited for studies in aqueous environments enables its wider use for fields such as biology and biomedicine in which aqueous environments are the norm.

  19. Acousto-optic tunable filter near-infrared spectroscopy for in-line monitoring liquid-liquid extraction of Gardenia jasminoides Ellis based on statistical analysis.

    Science.gov (United States)

    Wu, Sha; Jin, Ye; Liu, Qi-An; Wu, Jian-Xiong; Bi, Yu-An; Wang, Zhen-Zhong; Xiao, Wei

    2015-10-01

    This study aimed to monitor liquid-liquid extraction of Gardenia jasminoides Ellis (Zhizi in Chinese) using in-line near-infrared spectroscopy. Shanzhiside (SZS), deacetyl asperulosidic acid methyl ester (DAAME), genipin-1-β-D-gentiobioside (GG), geniposide (GS), total acids (TA) and soluble solid content (SSC) were selected as quality control indicators, and measured by reference methods. Both partial least-squares regression (PLSR) and back propagation artificial neural networks (BP-ANN) were applied to create models to predict the content of above indicators. Paired-samples t-test and nonparametric test were used to compare differences in predictive values between two models of each indicator. Relative standard error of prediction (RSEP) and mean absolute percentage error (MAPE) were used to evaluate the predictive accuracy of the established models. The results showed that there was no significant difference in predicting DAAME, GS and TA between two models. However, PLSR model gave better accuracy in predicting GG and SZS than BP-ANN model. The BP-ANN model of SSC was better than PLSR model. This study shows that NIR spectroscopy can be used for rapid and accurate analysis of quality control indicators in the liquid-liquid extraction of Zhizi. Simultaneously, this study can serve as technical support for the application of NIR spectroscopy in the industrial production process.

  20. Electrical probing of submicroliter liquid using graphene strip transistors built on a nanopipette.

    Science.gov (United States)

    Chen, Chang-Hsiao; Lin, Cheng-Te; Lee, Yi-Hsien; Liu, Keng-Ku; Su, Ching-Yuan; Zhang, Wenjing; Li, Lain-Jong

    2012-01-09

    Graphene sheets made by chemical vapor deposition are transferred onto a glass nanopipette to form graphene strips. Two strips are connected at the nanopipette tip end to form a transistor channel. This graphene-based transistor can be operated in a liquid-gating condition, thereby allowing the electrical detection of the pH value of a droplet with submicroliter volume. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids

    OpenAIRE

    Won Lee Seung; Bang In Cheol; Ju Park Eun; Park Hyung Wook

    2011-01-01

    Abstract Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal condit...

  2. Electrically controlled phases of partially polarized light and orientational Kerr effect in liquid crystal ferroelectrics

    Directory of Open Access Journals (Sweden)

    Kiselev Alexei D.

    2017-01-01

    Full Text Available We study the electro-optic properties of subwavelength-pitch deformed-helix ferroelectric liquid crystals illuminated with partially polarized light. In an experimental setup based on the Mach-Zehnder interferometer, it is found that the interference pattern crucially depends on the degree of polarization of the incident light. We evaluate the electric field dependence of both the Pancharatnam relative phase and the geometric phase for the general case of nonunitarily evolving mixed polarization states.

  3. High Power Electric Double-Layer Capacitors based on Room-Temperature Ionic Liquids and Nanostructured Carbons

    Science.gov (United States)

    Perez, Carlos R.

    The efficient storage of electrical energy constitutes both a fundamental challenge for 21st century science and an urgent requirement for the sustainability of our technological civilization. The push for cleaner renewable forms of energy production, such as solar and wind power, strongly depends on a concomitant development of suitable storage methods to pair with these intermittent sources, as well as for mobile applications, such as vehicles and personal electronics. In this regard, Electrochemical Double-Layer Capacitors (supercapacitors) represent a vibrant area of research due to their environmental friendliness, long lifetimes, high power capability, and relative underdevelopment when compared to electrochemical batteries. Currently supercapacitors have gravimetric energies one order of magnitude lower than similarly advanced batteries, while conversly enjoying a similar advantage over them in terms of power. The challenge is to increase the gravimentric energies and conserve the high power. On the material side, research focuses on highly porous supports and electrolytes, the critical components of supercapacitors. Through the use of electrolyte systems with a wider electrochemical stability window, as well as properly tailored carbon nanomaterials as electrodes, significant improvements in performance are possible. Room Temperature Ionic Liquids and Carbide-Derived Carbons are promising electrolytes and electrodes, respectively. RTILs have been shown to be stable at up to twice the voltage of organic solvent-salt systems currently employed in supercapacitors, and CDCs are tunable in pore structure, show good electrical conductivity, and superior demonstrated capability as electrode material. This work aims to better understand the interplay of electrode and electrolyte parameters, such as pore structure and ion size, in the ultimate performance of RTIL-based supercapacitors in terms of power, energy, and temperature of operation. For this purpose, carbon

  4. Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids

    Directory of Open Access Journals (Sweden)

    Won Lee Seung

    2011-01-01

    Full Text Available Abstract Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal conditions were achieved when capacitance was 30 μF, wire length was 38 mm, liquid volume was 500 mL, and the liquid type was deionized water. The average Ag nanoparticle size in water was 118.9 nm and the zeta potential was -42.5 mV. The critical heat flux of the 0.001-vol.% Ag nanofluid was higher than pure water.

  5. Optimal synthesis and characterization of Ag nanofluids by electrical explosion of wires in liquids.

    Science.gov (United States)

    Ju Park, Eun; Won Lee, Seung; Bang, In Cheol; Park, Hyung Wook

    2011-03-15

    Silver nanoparticles were produced by electrical explosion of wires in liquids with no additive. In this study, we optimized the fabrication method and examined the effects of manufacturing process parameters. Morphology and size of the Ag nanoparticles were determined using transmission electron microscopy and field-emission scanning electron microscopy. Size and zeta potential were analyzed using dynamic light scattering. A response optimization technique showed that optimal conditions were achieved when capacitance was 30 μF, wire length was 38 mm, liquid volume was 500 mL, and the liquid type was deionized water. The average Ag nanoparticle size in water was 118.9 nm and the zeta potential was -42.5 mV. The critical heat flux of the 0.001-vol.% Ag nanofluid was higher than pure water.

  6. Further study on heredity of liquid aluminum modified by electric pulse

    Directory of Open Access Journals (Sweden)

    Qi Jingang

    2011-08-01

    Full Text Available The remarkable heredity of liquid aluminum modified by electric pulse (EP, EPM has been uncovered. For better understanding from all aspects on the hereditary properties, the present research deals with the heredity destruction and the secondary EPM procedure. It is shown that the secondary EPM is capable of preventing the heredity reduction of EP-modified liquid aluminum, and that the final refining effect has a close relationship with technique parameters of the secondary EPM. Furthermore, at a certain superheated temperature depending on the initial EPM technique parameters, the heredity relationship of EP-modified liquid aluminum can be cut off during remelting. High temperature X-ray diffraction combining with the DSC tests also indicates that the EP-induced structure changes have almost disappeared at an elevated remelting temperature.

  7. Type of tunable guided-mode resonance filter based on electro-optic characteristic of polymer-dispersed liquid crystal.

    Science.gov (United States)

    Wang, Qi; Zhang, Dawei; Huang, Yuanshen; Ni, Zhengji; Chen, Jiabi; Zhong, Yangwan; Zhuang, Songlin

    2010-04-15

    A narrowband guided-mode resonance filter (GMRF) incorporating polymer-dispersed liquid crystal (PDLC) is designed. Simulating the characteristics of the filter with rigorous coupled-wave analysis, we find that the resonance wavelength of the new kind of GMRF can be tuned from 672.4 to 698.4 nm by varying the refractive index of the PDLC layer with the applied voltage. Furthermore, the resonance wavelengths vary in a linear fashion with respect to the refractive index of the PDLC layer. Therefore, the desired resonance wavelength can be conveniently selected and tuned in a tuning range of 26 nm by using the applied voltage.

  8. Instability of Slender Liquid Jet in AC Electric Field of Arbitrary Frequency

    Science.gov (United States)

    Demekhin, Evgeny A.; Polyanskikh, Sergey V.

    2010-09-01

    In the present work stability of capillary micro-jet of electrolyte solution in alternating longitudinal electric field is investigated theoretically. The gravity effects are neglected. The problem is described by strongly coupled nonlinear system of PDEs for ion transport, electric field and fluid flow under assumption of a viscous Newtonian liquid. The Debye layer thickness is supposed to be small compared with initial jet radius. The Peclet number based on the Debye layer thickness is assumed to be small. These assumptions lead to substantial simplification of the problem. Slender-body theory is used to further simplification of initial statement. Used asymptotic method allows to reduce initially infinite system to three-dimensional ODE with time-periodic coefficients. It is shown that monodromy operator has the only real unstable multiplier. In the case of high-frequency alternating electric field the results showed good agreement with the ones provided by averaging theory.

  9. 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....

  10. An Investigation of Sliding Electrical Contact in Rail Guns and the Development of Grooved-Rail Liquid-Metal Interfaces

    National Research Council Canada - National Science Library

    Adamy, Mark

    2001-01-01

    ... the rails and yet provide sufficient electrical contact to sustain arc-free high-current flow is desirable, This thesis investigates the use of liquid metal as an interface material between the sliding...

  11. Experimental study of electric discharge propagation in gas bubbles in liquid

    Science.gov (United States)

    Faust, Jessica; Gershman, Sophia

    2013-10-01

    The studies of pulsed electrical discharges in gas bubbles in liquids continue to generate interest by their practical applications to the water treatment as well their theoretical significance for the understanding of the discharge propagation along liquid surfaces. Computational models suggest that the discharge path depends on the ratio of the dielectric constant of the liquid and the gas. This study investigates the formation and propagation of the discharge inside a gas bubble in water and glycerin (dielectric constants of approximately 80 and 41, respectively, at 20 C). The discharge is generated by a 1 μs pulse of 10-15 kV applied between a needle electrode piercing the bubble wall and a disk electrode submerged in the liquid. Time-resolved 5-10 ns exposure ICCD images are used to compare the discharge path in Ar, O2, and air bubbles in the two liquid dielectrics. 10 nm bandpass filters are used to image the behavior of various excited species, ex. Ar +, OH. Experimental results are compared to the previous modeling results.

  12. Non-Fermi Liquid Behavior and Continuously Tunable Resistivity Exponents in the Anderson-Hubbard Model at Finite Temperature

    Science.gov (United States)

    Patel, Niravkumar D.; Mukherjee, Anamitra; Kaushal, Nitin; Moreo, Adriana; Dagotto, Elbio

    2017-08-01

    We employ a recently developed computational many-body technique to study for the first time the half-filled Anderson-Hubbard model at finite temperature and arbitrary correlation U and disorder V strengths. Interestingly, the narrow zero temperature metallic range induced by disorder from the Mott insulator expands with increasing temperature in a manner resembling a quantum critical point. Our study of the resistivity temperature scaling Tα for this metal reveals non-Fermi liquid characteristics. Moreover, a continuous dependence of α on U and V from linear to nearly quadratic is observed. We argue that these exotic results arise from a systematic change with U and V of the "effective" disorder, a combination of quenched disorder and intrinsic localized spins.

  13. Enhanced tunability of electrical and magnetic properties in (La,Sr)MnO3 thin films via field-assisted oxygen vacancy modulation

    Science.gov (United States)

    Wong, Hon Fai; Ng, Sheung Mei; Cheng, Wang Fai; Liu, Yukuai; Chen, Xinxin; von Nordheim, Danny; Mak, Chee Leung; Dai, Jiyan; Ploss, Bernd; Leung, Chi Wah

    2017-12-01

    We investigated the tunability of the transport and magnetic properties in 7.5 nm La0.7Sr0.3MnO3 (LSMO) epitaxial films in a field effect geometry with the ferroelectric copolymer P(VDF-TrFE) as the gate insulator. Two different switching behaviors were observed upon application of gate voltages with either high or low magnitudes. The application of single voltage pulses of alternating polarity with an amplitude high enough to switch the remanent polarization of the ferroelectric copolymer led to a 15% change of the resistance of the LSMO channel at temperature 300 K (but less than 1% change at 20 K). A minimal shift of the peak in the resistance-temperature plot was observed, implying that the Curie temperature TC of the manganite layer is not changed. Alternatively, the application of a chain of low voltage pulses was found to shift TC by more than 16 K, and a change of the channel resistance by a 45% was obtained. We attribute this effect to the field-assisted injection and removal of oxygen vacancies in the LSMO layer, which can occur across the thickness of the oxide film. By controlling the oxygen migration, the low-field switching route offers a simple method for modulating the electric and magnetic properties of manganite films.

  14. Tunable Beam Diffraction in Infiltrated Microstructured Fibers

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.

    We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites.......We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites....

  15. Electric-field tunable spin waves in PMN-PT/NiFe heterostructure: Experiment and micromagnetic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ziȩtek, Slawomir, E-mail: zietek@agh.edu.pl [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Chȩciński, Jakub [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059 Kraków (Poland); Frankowski, Marek; Skowroński, Witold; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland)

    2017-04-15

    We present a comprehensive theoretical and experimental study of voltage-controlled standing spin waves resonance (SSWR) in PMN-PT/NiFe multiferroic heterostructures patterned into microstrips. A spin-diode technique was used to observe ferromagnetic resonance (FMR) mode and SSWR in NiFe strip mechanically coupled with a piezoelectric substrate. Application of an electric field to a PMN-PT creates a strain in permalloy and thus shifts the FMR and SSWR fields due to the magnetostriction effect. The experimental results are compared with micromagnetic simulations and a good agreement between them is found for dynamics of FMR and SSWR with and without electric field. Moreover, micromagnetic simulations enable us to discuss the amplitude and phase spatial distributions of FMR and SSWR modes, which are not directly observable by means of spin diode detection technique.

  16. Out-of-plane strain and electric field tunable electronic properties and Schottky contact of graphene/antimonene heterostructure

    Science.gov (United States)

    Phuc, Huynh V.; Hieu, Nguyen N.; Hoi, Bui D.; Phuong, Le T. T.; Hieu, Nguyen V.; Nguyen, Chuong V.

    2017-12-01

    In this paper, the electronic properties of graphene/monolayer antimonene (G/m-Sb) heterostructure have been studied using the density functional theory (DFT). The effects of out-of-plane strain (interlayer coupling) and electric field on the electronic properties and Schottky contact of the G/m-Sb heterostructure are also investigated. The results show that graphene is bound to m-Sb layer by a weak van-der-Waals interaction with the interlayer distance of 3.50 Å and the binding energy per carbon atom of -39.62 meV. We find that the n-type Schottky contact is formed at the G/m-Sb heterostructure with the Schottky barrier height (SBH) of 0.60 eV. By varying the interlayer distance between graphene and the m-Sb layer we can change the n-type and p-type SBH at the G/m-Sb heterostructure. Especially, we find the transformation from n-type to p-type Schottky contact with decreasing the interlayer distance. Furthermore, the SBH and the Schottky contact could be controlled by applying the perpendicular electric field. With the positive electric field, electrons can easily transfer from m-Sb to graphene layer, leading to the transition from n-type to p-type Schottky contact.

  17. Method and apparatus for electrokinetic co-generation of hydrogen and electric power from liquid water microjets

    Science.gov (United States)

    Saykally, Richard J; Duffin, Andrew M; Wilson, Kevin R; Rude, Bruce S

    2013-02-12

    A method and apparatus for producing both a gas and electrical power from a flowing liquid, the method comprising: a) providing a source liquid containing ions that when neutralized form a gas; b) providing a velocity to the source liquid relative to a solid material to form a charged liquid microjet, which subsequently breaks up into a droplet spay, the solid material forming a liquid-solid interface; and c) supplying electrons to the charged liquid by contacting a spray stream of the charged liquid with an electron source. In one embodiment, where the liquid is water, hydrogen gas is formed and a streaming current is generated. The apparatus comprises a source of pressurized liquid, a microjet nozzle, a conduit for delivering said liquid to said microjet nozzle, and a conductive metal target sufficiently spaced from said nozzle such that the jet stream produced by said microjet is discontinuous at said target. In one arrangement, with the metal nozzle and target electrically connected to ground, both hydrogen gas and a streaming current are generated at the target as it is impinged by the streaming, liquid spray microjet.

  18. Electric field stabilization of viscous liquid layers coating the underside of a surface

    Science.gov (United States)

    Anderson, Thomas G.; Cimpeanu, Radu; Papageorgiou, Demetrios T.; Petropoulos, Peter G.

    2017-05-01

    We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a horizontal surface in the presence of an electric field applied parallel to the surface. The model includes the effect of bounding solid dielectric regions above and below the liquid-air system that are typically found in experiments. The competition between gravitational forces, surface tension, and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semispectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations using the volume-of-fluid methodology and assess the accuracy of the obtained solutions in the long-wave (thin-film) regime when varying the electric field strength from zero up to the point when complete stabilization occurs. We employ DNS to examine the limitations of the asymptotically derived behavior as the liquid layer thickness increases and find excellent agreement even beyond the regime of strict applicability of the asymptotic solution. Finally, the asymptotic and computational approaches are utilized to identify robust and efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

  19. Label-free biomolecular detection at electrically displaced liquid interfaces using interfacial electrokinetic transduction (IET).

    Science.gov (United States)

    Mavrogiannis, Nicholas; Crivellari, Francesca; Gagnon, Zachary R

    2016-03-15

    Biosensors require a biorecognition element that specifically binds to a target analyte, and a signal transducer, which converts this targeted binding event into a measurable signal. While current biosensing methods are capable of sensitively detecting a variety of target analytes in a laboratory setting, there are inherent difficulties in developing low-cost portable biosensors for point-of-care diagnostics using traditional optical, mass, or electroanalytical-based signal transducers. It is therefore important to develop new biosensing transducer elements for recognizing binding events at low cost and in portable environments. Here, we demonstrate a novel electrokinetic liquid biosensing method for the sensitive label-free detection of a model biomolecule against a background of serum protein. The biosensor is based on the motion of a microfluidic-generated electrical liquid interface when subjected to an external alternating current electrical field. We demonstrate that the electric field-induced motion of the interface can be used as a sensitive and specific transducer for the detection of avidin at femtomolar concentrations in solution. This new detection strategy does not require surface functionalization or fluorescent labels, and has the potential to serve as a sensitive low-cost method for portable biomarker detection. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Electrically induced structure transition in nematic liquid crystal droplets with conical boundary conditions

    Science.gov (United States)

    Rudyak, V. Yu.; Krakhalev, M. N.; Sutormin, V. S.; Prishchepa, O. O.; Zyryanov, V. Ya.; Liu, J.-H.; Emelyanenko, A. V.; Khokhlov, A. R.

    2017-11-01

    Polymer-dispersed liquid crystal composites have been a focus of study for a long time for their unique electro-optical properties and manufacturing by "bottom-up" techniques at large scales. In this paper, nematic liquid crystal oblate droplets with conical boundary conditions (CBCs) under the action of electric field were studied by computer simulations and polarized optical microscopy. Droplets with CBCs were shown to prefer an axial-bipolar structure, which combines a pair of boojums and circular disclinations on a surface. In contrast to droplets with degenerate planar boundary conditions (PBCs), hybridization of the two structure types in droplets with CBCs leads to a two-minima energy profile, resulting in an abrupt structure transition and bistable behavior of the system. The nature of the low-energy barrier in droplets with CBCs makes it highly sensitive to external stimuli, such as electric or magnetic fields, temperature, and light. In particular, the value of the electric field of the structure reorientation in droplets with CBCs was found to be a few times smaller than the one for droplets with PBCs, and the droplet state remained stable after switching off the voltage.

  1. One-step electric-field driven methane and formaldehyde synthesis from liquid methanol.

    Science.gov (United States)

    Cassone, Giuseppe; Pietrucci, Fabio; Saija, Franz; Guyot, François; Saitta, A Marco

    2017-03-01

    The reaction pathways connecting methanol to methane and formaldehyde are among the most emblematic in chemistry because of their outstanding interest in the fields of energy, synthesis, and bio- and geo-chemistry. Despite of its fundamental nature, the one-pot synthesis of formaldehyde and methane stemming from methanol has never been reported before. Here we present a study, based on ab initio molecular dynamics and free-energy methods, in which the simultaneous oxidation and reduction (i.e., the disproportionation) of liquid methanol into methane and formaldehyde has been achieved at ambient temperature through the application of a static electric field. Because strong electric fields can be generated in the proximity of field emitter tips, this finding shows that the challenge of experimentally disproportionating methanol into formaldehyde and methane could be attempted. We show that the methanol "solvent" molecules play a major role in this process and that the chemical pathway connecting methanol to the detected products in the bulk liquid phase is very different from its reproduced gas-phase counterpart. Finally, we demonstrate that switching on an external electric field drastically modifies the reaction network of methanol, lowering some activation barriers, stabilizing the methane and formaldehyde products, and opening otherwise difficult-to-achieve chemical routes.

  2. Light-induced electric field generated by photovoltaic substrates investigated through liquid crystal reorientation

    Science.gov (United States)

    Lucchetti, L.; Kushnir, K.; Reshetnyak, V.; Ciciulla, F.; Zaltron, A.; Sada, C.; Simoni, F.

    2017-11-01

    Liquid crystal reorientation is exploited to analyze the electric field generated by light irradiation in iron-doped lithium niobate crystals. The evaluation of the strength of this light-induced field is based on the measurement of the phase shift induced in a probe light beam by a liquid crystal cell built with two z-cut iron-doped lithium niobate crystals as substrates. Then, the field profile has been determined starting from a Gaussian-like surface charge density following the model described in the text. The director profile corresponding to the modelled electric field is in good agreement with the director reorientation evaluated experimentally by means of the light-induced phase shift. This investigation gives a new approach to study the effects based on the photovoltaic response of lithium niobate crystals. Moreover, the characterization of the electric field optically generated inside the LC layer is highly desirable in view of the realization of new all-optical devices to be integrated in optofluidic platforms.

  3. Intermediate Temperature Hybrid Fuel Cell System for the Conversion of Natural to Electricity and Liquid Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Theodore [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-11-22

    This goal of this project was to develop a new hybrid fuel cell technology that operates directly on natural gas or biogas to generate electrical energy and to produce ethane or ethylene from methane, the main component of natural gas or biogas, which can be converted to a liquid fuel or high-value chemical using existing process technologies. By taking advantage of the modularity and scalability of fuel cell technology, this combined fuel cell/chemical process technology targets the recovery of stranded natural gas available at the well pad or biogas produced at waste water treatment plants and municipal landfills by converting it to a liquid fuel or chemical. By converting the stranded gas to a liquid fuel or chemical, it can be cost-effectively transported to market thus allowing the stranded natural gas or biogas to be monetized instead of flared, producing CO2, a greenhouse gas, because the volumes produced at these locations are too small to be economically recovered using current gas-to-liquids process technologies.

  4. Fabrication and Characterization of Ni-CNT Composites by Electrical Explosion of Wire in Different Liquids

    Directory of Open Access Journals (Sweden)

    Thuyet-Nguyen M.

    2017-06-01

    Full Text Available In this study, Ni-CNT powders and colloids were synthesized via the Electrical explosion of wire (EEW in different liquid conditions. The influence of ambient solvents (D.I. Water, ethanol, methanol, acetone and ethylene-glycol on characteristics of the as-synthesized Ni-CNT was investigated. The morphology and size were observed by field emission scanning electron microscopy (FE-SEM. The Ni particles were spherical or near spherical shape. The phase of the composite powders analyzed via X-ray diffraction demonstrate the presence of CNTs in composite powders is not affect the structure of Ni. However, the phase of the composites was changed based on the changing of liquid conditions. Stability of colloids was investigated by Turbiscan technique. Magnetic properties were also investigated by Vibrating sample magnetometer (VSM at room temperature. The as-synthesized composite powders revealed a ferromagnetic characteristic material.

  5. Effects of electric field on thermodynamics and ordering of a dipolar liquid

    Science.gov (United States)

    Johari, G. P.

    2016-10-01

    We propose that an electric field's role in changing the structural disorder may be investigated by comparing the field-induced entropy decrease, ΔES, against the pressure-induced and cooling-induced entropy decreases, ΔpS and ΔTS, respectively, for the same increase in the dielectric α-relaxation time, Δτα, or in the viscosity. If these three quantities are found to be the same, the change in the number of microstates, Δln Ω = ΔS/R, would be the same whether there is an electric field-induced dipole vector alignment, or not. The available data [S. Samanta and R. Richert, J. Chem. Phys. 142, 044504 (2015)] show that ΔES ≅ ΔpS, and ΔES ≅ ΔTS. We further argue that in the case of conformational disorder without hydrodynamics, as for a flexible molecule's orientationally disordered or plastic crystal, ΔTS would be more negative than ΔES for the same increase in Δτα. For cyclo-octanol plastic crystal, whose octyl-ring would lose some of its dielectrically inactive conformational degrees of freedom on cooling, ΔTS is five-times ΔES. Hence the entropy of such crystals may not be related to their τα, an aspect relevant to certain biopolymer crystals. We also mention other effects of E. The findings are relevant to a number of recent studies on the analysis of the effect of electric field on a liquid's properties. The method can be used to study the role of other entropy-altering variables in liquid crystals and ferromagnetic liquids.

  6. Electrically tunable transport and high-frequency dynamics in antiferromagnetic S r3I r2O7

    Science.gov (United States)

    Seinige, Heidi; Williamson, Morgan; Shen, Shida; Wang, Cheng; Cao, Gang; Zhou, Jianshi; Goodenough, John B.; Tsoi, Maxim

    2016-12-01

    We report dc and high-frequency transport properties of antiferromagnetic S r3I r2O7 . Temperature-dependent resistivity measurements show that the activation energy of this material can be tuned by an applied dc electrical bias. The latter allows for continuous variations in the sample resistivity of as much as 50% followed by a reversible resistive switching at higher biases. Such a switching is of high interest for antiferromagnetic applications in high-speed memory devices. Interestingly, we found the switching behavior to be strongly affected by a high-frequency (microwave) current applied to the sample. The microwaves at 3-7 GHz suppress the dc switching and produce resonancelike features that we tentatively associated with the dissipationless magnonics recently predicted to occur in antiferromagnetic insulators subject to ac electric fields. We have characterized the effects of microwave irradiation on electronic transport in S r3I r2O7 as a function of microwave frequency and power, strength and direction of external magnetic field, strength and polarity of applied dc bias, and temperature. Our observations support the potential of antiferromagnetic materials for high-speed/high-frequency spintronic applications.

  7. Broad-Range Electrically Tunable Plasmonic Resonances of a Multilayer Coaxial Nanohole Array with an Electroactive Polymer Wrapper.

    Science.gov (United States)

    Zhou, Ziwei; Yu, Ye; Sun, Ningwei; Möhwald, Helmuth; Gu, Panpan; Wang, Liyan; Zhang, Wei; König, Tobias A F; Fery, Andreas; Zhang, Gang

    2017-10-11

    Plasmonic assemblies featuring high sensitivity that can be readily shifted by external fields are the key for sensitive and versatile sensing devices. In this paper, a novel fast-responsive plasmonic nanocomposite composed of a multilayer nanohole array and a responsive electrochromic polymer is proposed with the plasmonic mode appearance vigorously cycled upon orthogonal electrical stimuli. In this nanocomposite, the coaxially stacked plasmonic nanohole arrays can induce multiple intense Fano resonances, which result from the crosstalk between a broad surface plasmon resonance (SPR) and the designed discrete transmission peaks with ultrahigh sensitivity; the polymer wrapper could provide the sensitive nanohole array with real-time-varied surroundings of refractive indices upon electrical stimuli. Therefore, a pronounced pure electroplasmonic shift up to 72 nm is obtained, which is the largest pure electrotuning SPR range to our knowledge. The stacked nanohole arrays here are also directly used as a working electrode, and they ensure sufficient contact between the working electrode (plasmonic structure) and the electroactive polymer, thus providing considerably improved response speed (within 1 s) for real-time sensing and switching.

  8. Electrically controllable in-line-type polarizer using polymer-dispersed liquid-crystal spliced optical fibers.

    Science.gov (United States)

    Baek, Seungin; Jeong, Yoonchan; Kim, Hak-Rin; Lee, Sin-Doo; Lee, Byoungho

    2003-09-01

    The polarization-dependent transmission of light through an electrically controllable in-line-type polarizer that is made from polymer-dispersed liquid-crystal spliced optical fibers is discussed experimentally and theoretically. This in-line-type optical splicing method has the advantage of low transmission loss when it is applied in optical fiber communication systems. An anomalous diffraction approach is used to compute the scattering cross section of polymer-dispersed liquid-crystal droplets. The experimental results are supported by a theoretical analysis. This device can be employed in electrically controllable in-line-type polarizers and has the potential to yield electrically controllable polarization-dependent loss compensators.

  9. Polymers, liquids and colloids in electric fields Interfacial Instabilities, orientation and phase transitions

    CERN Document Server

    Steiner, Ullrich

    2009-01-01

    This unique book aims to expose the reader to a wide range of phenomena occurring when soft matter systems are put under the influence of an external electric field. The book shows how an electric field can be used to affect objects at the submicron scale, and how it controls the phase behavior of liquids and polymers. The main focus is on the basic underlying mechanisms. Some technological applications are dealt with as well. Book chapters are arranged in a logical order, from “simple” systems to more complicated ones. In addition, each topic is covered by the mixed bag of theory, experiment and simulation; and this will give the reader a broad perspective of the underlying physical phenomena

  10. Electrically Controlled Plasmonic Lasing Resonances with Silver Nanoparticles Embedded in Amplifying Nematic Liquid Crystals

    CERN Document Server

    Wang, Chin

    2014-01-01

    We demonstrate an electrically controlled coherent random lasing with silver nano-particles dispersed in a dye-doped nematic liquid crystal (NLC), in which external electric field dependent emission intensity and frequency-splitting are recorded. A modified rate equation model is proposed to interpret the observed coherent lasing, which is a manifestation of double enhancements, caused by the plasmon-polariton near-fields of Ag particles, on the population inversion of laser dye molecules and the optical energy density of lasing modes. The noticeable quenching of lasing resonances in a weak applied field is due to the dynamic light scattering by irregular director fluctuations of the NLC host, which wash out the coherent interference among different particle palsmon-polariton fields. This provides a proof to support that the present lasing resonances are very sensitive to the dielectric perturbations in the host medium and thus are likely associated with some coupled plasmonic oscillations of metal nanopartic...

  11. Infiltrated microstructured fibers as tunable and nonlinear optical devices

    DEFF Research Database (Denmark)

    Rosberg, Christian Romer; Bennet, Francis; Neshev, Dragomir N.

    We study the light guiding properties of microstructured optical fibers infiltrated with nonlinear liquids and demonstrate their applicability for spatial beam control in novel type tunable and nonlinear optical devices.......We study the light guiding properties of microstructured optical fibers infiltrated with nonlinear liquids and demonstrate their applicability for spatial beam control in novel type tunable and nonlinear optical devices....

  12. Synthetically chemical-electrical mechanism for controlling large scale reversible deformation of liquid metal objects

    Science.gov (United States)

    Zhang, Jie; Sheng, Lei; Liu, Jing

    2014-11-01

    Reversible deformation of a machine holds enormous promise across many scientific areas ranging from mechanical engineering to applied physics. So far, such capabilities are still hard to achieve through conventional rigid materials or depending mainly on elastomeric materials, which however own rather limited performances and require complicated manipulations. Here, we show a basic strategy which is fundamentally different from the existing ones to realize large scale reversible deformation through controlling the working materials via the synthetically chemical-electrical mechanism (SCHEME). Such activity incorporates an object of liquid metal gallium whose surface area could spread up to five times of its original size and vice versa under low energy consumption. Particularly, the alterable surface tension based on combination of chemical dissolution and electrochemical oxidation is ascribed to the reversible shape transformation, which works much more flexible than many former deformation principles through converting electrical energy into mechanical movement. A series of very unusual phenomena regarding the reversible configurational shifts are disclosed with dominant factors clarified. This study opens a generalized way to combine the liquid metal serving as shape-variable element with the SCHEME to compose functional soft machines, which implies huge potential for developing future smart robots to fulfill various complicated tasks.

  13. High-performance liquid-catalyst fuel cell for direct biomass-into-electricity conversion.

    Science.gov (United States)

    Liu, Wei; Mu, Wei; Deng, Yulin

    2014-12-01

    Herein, we report high-performance fuel cells that are catalyzed solely by polyoxometalate (POM) solution without any solid metal or metal oxide. The novel design of the liquid-catalyst fuel cells (LCFC) changes the traditional gas-solid-surface heterogeneous reactions to liquid-catalysis reactions. With this design, raw biomasses, such as cellulose, starch, and even grass or wood powders can be directly converted into electricity. The power densities of the fuel cell with switchgrass (dry powder) and bush allamanda (freshly collected) are 44 mW cm(-2) and 51 mW cm(-2) respectively. For the cellulose-based biomass fuel cell, the power density is almost 3000 times higher than that of cellulose-based microbial fuel cells. Unlike noble-metal catalysts, POMs are tolerant to most organic and inorganic contaminants. Therefore, almost any raw biomass can be used directly to produce electricity without prior purification. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Synthetically chemical-electrical mechanism for controlling large scale reversible deformation of liquid metal objects.

    Science.gov (United States)

    Zhang, Jie; Sheng, Lei; Liu, Jing

    2014-11-19

    Reversible deformation of a machine holds enormous promise across many scientific areas ranging from mechanical engineering to applied physics. So far, such capabilities are still hard to achieve through conventional rigid materials or depending mainly on elastomeric materials, which however own rather limited performances and require complicated manipulations. Here, we show a basic strategy which is fundamentally different from the existing ones to realize large scale reversible deformation through controlling the working materials via the synthetically chemical-electrical mechanism (SCHEME). Such activity incorporates an object of liquid metal gallium whose surface area could spread up to five times of its original size and vice versa under low energy consumption. Particularly, the alterable surface tension based on combination of chemical dissolution and electrochemical oxidation is ascribed to the reversible shape transformation, which works much more flexible than many former deformation principles through converting electrical energy into mechanical movement. A series of very unusual phenomena regarding the reversible configurational shifts are disclosed with dominant factors clarified. This study opens a generalized way to combine the liquid metal serving as shape-variable element with the SCHEME to compose functional soft machines, which implies huge potential for developing future smart robots to fulfill various complicated tasks.

  15. System dynamics of the competition of municipal solid waste to landfill, electricity, and liquid fuel in California

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, Jessica; Malczynski, Leonard A.; Manley, Dawn Kataoka

    2014-03-01

    A quantitative system dynamics model was created to evaluate the economic and environmental tradeoffs between biomass to electricity and to liquid fuel using MSW biomass in the state of California as a case study. From an environmental perspective, landfilling represents the worst use of MSW over time, generating more greenhouse gas (GHG) emissions compared to converting MSW to liquid fuel or to electricity. MSW to ethanol results in the greatest displacement of GHG emissions per dollar spent compared to MSW to electricity. MSW to ethanol could save the state of California approximately $60 billion in energy costs by 2050 compared to landfilling, while also reducing GHG emissions state-wide by approximately 140 million metric tons during that timeframe. MSW conversion to electricity creates a significant cost within the state's electricity sector, although some conversion technologies are cost competitive with existing renewable generation.

  16. Direct conversion of fission energy into electricity in liquid gallium contact potential cell

    Energy Technology Data Exchange (ETDEWEB)

    Soh, T., E-mail: tes211@mail.usask.ca [Univ. of Saskatchewan, Dept. of Mechanical Engineering, Saskatoon, Saskatchewan (Canada); Sohtech R& D Inc., Saskatoon, Saskatchewan (Canada)

    2014-07-01

    Nuclear fission of uranium releases about 93% of its energy in the form of highly charged (up to 20+) and highly energetic fission fragment (83.5MeV average) and other ionizing radiations, including beta and gamma radiations. Liquid gallium is a semimetal that had been previously explored as a self recovering ionization media for alphavoltiac contact potential cell (CPC), and had been evaluated as a suitable replacement coolant for the next generation of fast reactor. By improving the neutronic aspect of a Liquid Gallium CPC (LGaCPC) with low neutron absorption construction materials, and by using a heterogeneous mixture of CANDU fuel grade uranium oxide powder (provided by CAMECO Inc.) and liquid gallium as its junction material, the direct conversion of fission energy to electricity has been observed when irradiated by the thermal neutron flux of the SLOWPOKE-II Research Reactor at the Saskatchewan Research Council. To further explore the effect of temperature on the operation of the LGaCPC, a High Temperature LGaCPC (HTLGaCPC), and a 6 meter high monolithic Large Volume Submersible Neutron Irradiation Chamber (LVSNIC) have been designed and constructed, which allow high temperature fission experiment up to 623K with a thermal neutron flux of 1.18 x 10{sup 10} n/cm{sup 2}/s and the result is presented here, along with discussions on the operating principle of the LGaCPC, and on the construction and measurement techniques used in this study. (author)

  17. Molecular dynamics simulation of the electrical double layer in ionic liquids

    Science.gov (United States)

    Kislenko, S. A.; Amirov, R. H.; Samoylov, I. S.

    2013-03-01

    The structure of the electrical double layer in the strongly coupled ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) near a basal plane of graphite was investigated by molecular dynamics simulation. It is found that near an uncharged surface the ionic liquid structure differs from its bulk structure and represents a well-ordered region, extending over ~2 nm from the surface. Interfacial layering is clearly observed at the surface. Ions adsorbed at the uncharged surface form the 2D molecular clusters of two types. In the first cluster type anions are self-assembled in a triangular lattice (containing ~5÷10 ions) while a cation subsystem is disordered. In the second one cations and anions self-assembled in a honeycomb lattice. The behavior of the screening potential in the ionic liquid [BMIM] [PF6] near the charged graphite surface with the charge density in the range -1.7 <= σ <= 1.7 μC/cm2 was investigated. It was shown that the potential is a nonmonotonic function of distance. Asymmetric behavior of the screening potential at surface charge densities equal in magnitude and opposite in sign was detected. It was shown that the local self-diffusion coefficients of ions in the vicinity of the surface correlate with the local ion density. Finally, the influence of temperature on the screening potential in the vicinity of a charged graphite surface has been studied. It was shown that the increase of temperature from 300 K to 400 K induces the decrease of the potential drop across the interface that implies the increase of the capacitance of the electrical double layer.

  18. Electric field measurements in nanosecond pulse discharges in air over liquid water surface

    Science.gov (United States)

    Simeni Simeni, Marien; Baratte, Edmond; Zhang, Cheng; Frederickson, Kraig; Adamovich, Igor V.

    2018-01-01

    Electric field in nanosecond pulse discharges in ambient air is measured by picosecond four-wave mixing, with absolute calibration by a known electrostatic field. The measurements are done in two geometries, (a) the discharge between two parallel cylinder electrodes placed inside quartz tubes, and (b) the discharge between a razor edge electrode and distilled water surface. In the first case, breakdown field exceeds DC breakdown threshold by approximately a factor of four, 140 ± 10 kV cm‑1. In the second case, electric field is measured for both positive and negative pulse polarities, with pulse durations of ∼10 ns and ∼100 ns, respectively. In the short duration, positive polarity pulse, breakdown occurs at 85 kV cm‑1, after which the electric field decreases over several ns due to charge separation in the plasma, with no field reversal detected when the applied voltage is reduced. In a long duration, negative polarity pulse, breakdown occurs at a lower electric field, 30 kV cm‑1, after which the field decays over several tens of ns and reverses direction when the applied voltage is reduced at the end of the pulse. For both pulse polarities, electric field after the pulse decays on a microsecond time scale, due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Measurements 1 mm away from the discharge center plane, ∼100 μm from the water surface, show that during the voltage rise, horizontal field component (Ex ) lags in time behind the vertical component (Ey ). After breakdown, Ey is reduced to near zero and reverses direction. Further away from the water surface (≈0.9 mm), Ex is much higher compared to Ey during the entire voltage pulse. The results provide insight into air plasma kinetics and charge transport processes near plasma-liquid interface, over a wide range of time scales.

  19. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Penwisa Pisitsak

    2012-01-01

    Full Text Available A thermotropic liquid crystalline polymer (LCP was blended with polycarbonate (PC and multiwalled carbon nanotube (CNT with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950 and Vectra V400P (V400P. The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by melt-blending in a twin-screw minicompounder and then injection molded using a mini-injection molder. The fibrillar domains of LCP were found only in the case of PC/VA950 blend. However, these fibrils turned into droplets in the presence of CNT. It was found that CNT preferentially remained inside the LCP domains as predicted from the value of spreading coefficient. The electrical conductivity showed the following order with the numbers in parenthesis representing the electrical percolation threshold of the compounds: PC/CNT (1% > PC/VA950P/CNT (1% > PC/V400P/CNT (3%. The storage modulus showed improvements with the addition of CNT and VA950.

  20. Water liquid-vapor interface subjected to various electric fields: A molecular dynamics study

    Science.gov (United States)

    Nikzad, Mohammadreza; Azimian, Ahmad Reza; Rezaei, Majid; Nikzad, Safoora

    2017-11-01

    Investigation of the effects of E-fields on the liquid-vapor interface is essential for the study of floating water bridge and wetting phenomena. The present study employs the molecular dynamics method to investigate the effects of parallel and perpendicular E-fields on the water liquid-vapor interface. For this purpose, density distribution, number of hydrogen bonds, molecular orientation, and surface tension are examined to gain a better understanding of the interface structure. Results indicate enhancements in parallel E-field decrease the interface width and number of hydrogen bonds, while the opposite holds true in the case of perpendicular E-fields. Moreover, perpendicular fields disturb the water structure at the interface. Given that water molecules tend to be parallel to the interface plane, it is observed that perpendicular E-fields fail to realign water molecules in the field direction while the parallel ones easily do so. It is also shown that surface tension rises with increasing strength of parallel E-fields, while it reduces in the case of perpendicular E-fields. Enhancement of surface tension in the parallel field direction demonstrates how the floating water bridge forms between the beakers. Finally, it is found that application of external E-fields to the liquid-vapor interface does not lead to uniform changes in surface tension and that the liquid-vapor interfacial tension term in Young's equation should be calculated near the triple-line of the droplet. This is attributed to the multi-directional nature of the droplet surface, indicating that no constant value can be assigned to a droplet's surface tension in the presence of large electric fields.

  1. Formation of radical and active chemical species in electrical discharge plasma in the presence of liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Locke, B.R.; Shih, K.Y.; Burlica, R. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemical and Biomedical Engineering

    2010-07-01

    This study investigated the interactions of plasma with liquid water using a combination of emission spectroscopy of radical and atomic species and direct measurements of more stable chemical compounds. The study focused on electrical discharge plasma formed directly in liquid water and on discharges formed in the gas phase above liquid water, in bubbles in liquid water, and in the gas phase with water droplet spray that result in a variety of active chemical species that can be used for pollution control as well as other applications in biomedical and materials engineering. The purpose was to improve the design and operation of plasma reactors for a variety of applications. This presentation also reviewed the mechanisms for the formation of active chemical species such as hydroxyl and other radicals, hydrogen peroxide and molecular hydrogen, in electrical discharge plasma formed in the presence of water.

  2. Electric Field-Responsive Mesoporous Suspensions: A Review

    Directory of Open Access Journals (Sweden)

    Seung Hyuk Kwon

    2015-12-01

    Full Text Available This paper briefly reviews the fabrication and electrorheological (ER characteristics of mesoporous materials and their nanocomposites with conducting polymers under an applied electric field when dispersed in an insulating liquid. Smart fluids of electrically-polarizable particles exhibit a reversible and tunable phase transition from a liquid-like to solid-like state in response to an external electric field of various strengths, and have potential applications in a variety of active control systems. The ER properties of these mesoporous suspensions are explained further according to their dielectric spectra in terms of the flow curve, dynamic moduli, and yield stress.

  3. Machining and Surface Characteristics of AISI 304L After Electric Discharge Machining for Copper and Graphite Electrodes in Different Dielectric Liquids

    National Research Council Canada - National Science Library

    S. Anjum; M. Shah; N. A. Anjum; S. Mehmood; W. Anwar

    2017-01-01

    In Electric Discharge Machining (EDM), the thermal energy used for material erosion depends on the intensity of electric sparks, the thermal conductivities of electrode material and the dielectric liquid...

  4. In situ fabrication of a tunable microlens.

    Science.gov (United States)

    Zhang, Lei; Wang, Zhiyuan; Wang, Yichuan; Qiu, Rui; Fang, Wei; Tong, Limin

    2015-08-15

    We demonstrate an optofluidic variable-focus microlens formed by a solid polydimethylsiloxane (PDMS) meniscus channel wall and a tunable liquid lens body. A novel method for in situ fabrication of the meniscus channel wall is developed by introducing liquid PDMS prepolymer into a microchannel followed by curing. Three-light manipulation techniques including tunable optical focusing, collimating, and diverging are realized by varying the refractive index (RI) of liquid lens body. Also, we present an absorption measurement of methylene blue (MB) with a collimated probing light, achieving a detection limit of 0.25 μM by using a 5-mm-long detection cell.

  5. Extensional flow of nematic liquid crystal with an applied electric field

    KAUST Repository

    CUMMINGS, L. J.

    2013-10-17

    Systematic asymptotic methods are used to formulate a model for the extensional flow of a thin sheet of nematic liquid crystal. With no external body forces applied, the model is found to be equivalent to the so-called Trouton model for Newtonian sheets (and fibres), albeit with a modified \\'Trouton ratio\\'. However, with a symmetry-breaking electric field gradient applied, behaviour deviates from the Newtonian case, and the sheet can undergo finite-time breakup if a suitable destabilizing field is applied. Some simple exact solutions are presented to illustrate the results in certain idealized limits, as well as sample numerical results to the full model equations. Copyright © Cambridge University Press 2013.

  6. Properties of zinc-oxide nanoparticles synthesized by electrical-discharge technique in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Tarasenko, Nikolai; Nevar, Alena; Nedelko, Mikhail [Institute of Physics, National Academy of Sciences of Belarus, 68 Nezalezhnasti Ave., 220072 Minsk (Belarus)

    2010-10-15

    The capabilities of a plasma-assisted technique based on electrical discharge in liquids for synthesis of N-doped and In-N codoped ZnO nanocrystals have been analyzed. The synthesis was carried out in a reactor containing aqueous ammonium nitrate solution of 0.001 M concentration. The pulsed-spark discharges between Zn-Zn and Zn-In electrodes have been used with further deposition of the synthesized particles on the silicon substrates. The optical properties, morphology, and composition of the nanoparticles formed were investigated by means of UV-Vis absorption spectroscopy, SEM, EDX, and XRD. As it followed from the XRD patterns the synthesized product was composed of hexagonal ZnO nanocrystals. The positions of the reflection peaks were observed to be varied with the composition of dopants. The influence of doping level on the structural and optical properties of synthesized nanoparticles has been discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Bifurcation properties of nematic liquid crystals exposed to an electric field: Switchability, bistability, and multistability

    KAUST Repository

    Cummings, L. J.

    2013-07-01

    Bistable liquid crystal displays (LCDs) offer the potential for considerable power savings compared with conventional (monostable) LCDs. The existence of two (or more) stable field-free states that are optically distinct means that contrast can be maintained in a display without an externally applied electric field. An applied field is required only to switch the device from one state to the other, as needed. In this paper we examine the basic physical principles involved in generating multiple stable states and the switching between these states. We consider a two-dimensional geometry in which variable surface anchoring conditions are used to control the steady-state solutions and explore how different anchoring conditions can influence the number and type of solutions and whether or not switching is possible between the states. We find a wide range of possible behaviors, including bistability, tristability, and tetrastability, and investigate how the solution landscape changes as the boundary conditions are tuned. © 2013 American Physical Society.

  8. Liquid cooled plate heat exchanger for battery cooling of an electric vehicle (EV)

    Science.gov (United States)

    Rahman, M. M.; Rahman, H. Y.; Mahlia, T. M. I.; Sheng, J. L. Y.

    2016-03-01

    A liquid cooled plate heat exchanger was designed to improve the battery life of an electric vehicle which suffers from premature aging or degradation due to the heat generation during discharging and charging period. Computational fluid dynamics (CFD) was used as a tool to analyse the temperature distribution when a constant surface heat flux was set at the bottom surface of the battery. Several initial and boundary conditions were set based on the past studies on the plate heat exchanger in the simulation software. The design of the plate heat exchanger was based on the Nissan Leaf battery pack to analyse the temperature patterns. Water at different mass flow rates was used as heat transfer fluid. The analysis revealed the designed plate heat exchanger could maintain the surface temperature within the range of 20 to 40°C which is within the safe operating temperature of the battery.

  9. Transient state study of electric motor heating and phase change solid-liquid cooling

    Energy Technology Data Exchange (ETDEWEB)

    Bellettre, J.; Sartre, V.; Lallemand, A. [Centre National de la Recherche Scientifique (CNRS), Centre de Thermique de Lyon, Villeurbanne, 69 (France); Biais, F. [AUXILEC, Chatou, 78 (France)

    1997-01-01

    This study reports on modelling of an autosynchronous electric motor stator, operating at transient state. The developed model, of the modal type, includes around 20 nodes. The simulations showed that hot spots are localized on the winding heads and led to the choice of a solid-liquid phase change cooling system. The comparison between simulation and experiment permitted the identification of unknown parameters. The model gives a good accuracy during steady-state and in the rising temperature phase. The modelling of the phase change cooling is realized by the addition of two nodes. The sensitivity analysis to PCM properties shows that the hot spot temperature decreases with increasing conductivities, inertia and latent heat of melting of the PCM and with decreasing melting temperature. Gallium (metal melting at 30{sup o}C) is the best PCM for the cooling of hot spots and P116 paraffin is the best non-metallic PCM. (author)

  10. A Review of Experiments and Modeling of Gas-Liquid Flow in Electrical Submersible Pumps

    Directory of Open Access Journals (Sweden)

    Jianjun Zhu

    2018-01-01

    Full Text Available As the second most widely used artificial lift method in petroleum production (and first in produced amount, electrical submersible pump (ESP maintains or increases flow rate by converting kinetic energy to hydraulic pressure of hydrocarbon fluids. To facilitate its optimal working conditions, an ESP has to be operated within a narrow application window. Issues like gas involvement, changing production rate and high oil viscosity, greatly impede ESP boosting pressure. Previous experimental studies showed that the presence of gas would cause ESP hydraulic head degradation. The flow behaviors inside ESPs under gassy conditions, such as pressure surging and gas pockets, further deteriorate ESP pressure boosting ability. Therefore, it is important to know what parameters govern the gas-liquid flow structure inside a rotating ESP and how it can be modeled. This paper presents a comprehensive review on the key factors that affect ESP performance under gassy flow conditions. Furthermore, the empirical and mechanistic models for predicting ESP pressure increment are discussed. The computational fluid dynamics (CFD-based modeling approach for studying the multiphase flow in a rotating ESP is explained as well. The closure relationships that are critical to both mechanistic and numerical models are reviewed, which are helpful for further development of more accurate models for predicting ESP gas-liquid flow behaviors.

  11. Dielectrophoretic- and electrohydrodynamic-driven translational motion of a liquid column in transverse electric fields

    Science.gov (United States)

    Esmaeeli, Asghar

    2016-07-01

    Computer simulations are performed to study translational motion and deformation of a liquid column or jet, in a plane perpendicular to its axis, due to a transverse electric field. A front tracking/finite difference scheme is used in conjunction with the Taylor-Melcher leaky dielectric theory to solve the governing equations. The column is confined within a rectangular channel, wall-bounded in the vertical direction and periodic in the horizontal direction. It is shown that perfect dielectric columns move toward electrode wall of shorter initial distance, but the leaky dielectric columns may move toward or away from it, depending on the relative importance of the ratios (drop fluid to suspending fluid) of their electric permittivity and conductivity. Furthermore, the degree of interface deformation might increase or decrease with the initial separation distance from the shorter electrode wall due to the same factor. Scaling arguments are used to discern the correlation between the translational velocity and the initial separation distance from the electrodes.

  12. Depth-enhanced integral imaging display system with electrically variable image planes using polymer-dispersed liquid-crystal layers.

    Science.gov (United States)

    Kim, Yunhee; Choi, Heejin; Kim, Joohwan; Cho, Seong-Woo; Kim, Youngmin; Park, Gilbae; Lee, Byoungho

    2007-06-20

    A depth-enhanced three-dimensional integral imaging system with electrically variable image planes is proposed. For implementing the variable image planes, polymer-dispersed liquid-crystal (PDLC) films and a projector are adopted as a new display system in the integral imaging. Since the transparencies of PDLC films are electrically controllable, we can make each film diffuse the projected light successively with a different depth from the lens array. As a result, the proposed method enables control of the location of image planes electrically and enhances the depth. The principle of the proposed method is described, and experimental results are also presented.

  13. Solar-Powered, Liquid-Desiccant Air Conditioner for Low-Electricity Humidity Control: Report and Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Dean, J.; Kozubal, E.; Herrmann, L.; Miller, J.; Lowenstein, A.; Barker, G.; Slayzak, S.

    2012-11-01

    The primary objective of this project was to demonstrate the capabilities of a new high-performance, liquid-desiccant dedicated outdoor air system (DOAS) to enhance cooling efficiency and comfort in humid climates while substantially reducing electric peak demand at Tyndall Air Force Base (AFB), which is 12 miles east of Panama City, Florida.

  14. Electrostatic and Electrochemical Nature of Liquid-Gated Electric-Double-Layer Transistors Based on Oxide Semiconductors

    NARCIS (Netherlands)

    Yuan, Hongtao; Shimotani, Hidekazu; Ye, Jianting; Yoon, Sungjae; Aliah, Hasniah; Tsukazaki, Atsushi; Kawasaki, Masashi; Iwasa, Yoshihiro

    2010-01-01

    The electric-double-layer (EDL) formed at liquid/solid interfaces provides a broad and interdisciplinary attraction in terms of electrochemistry, photochemistry, catalysts, energy storage, and electronics because of the large interfacial capacitance coupling and its ability for high-density charge

  15. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 10: Liquid-metal MHD systems. [energy conversion efficiency of electric power plants using liquid metal magnetohydrodynamics

    Science.gov (United States)

    Holman, R. R.; Lippert, T. E.

    1976-01-01

    Electric Power Plant costs and efficiencies are presented for two basic liquid-metal cycles corresponding to 922 and 1089 K (1200 and 1500 F) for a commercial applications using direct coal firing. Sixteen plant designs are considered for which major component equipment were sized and costed. The design basis for each major component is discussed. Also described is the overall systems computer model that was developed to analyze the thermodynamics of the various cycle configurations that were considered.

  16. PIEZOELECTRIC WAVEGUIDE SENSOR FOR MEASURING PULSE PRESSURE IN CLOSED LIQUID VOLUMES AT HIGH VOLTAGE ELECTRIC DISCHARGE

    Directory of Open Access Journals (Sweden)

    V. G. Zhekul

    2017-10-01

    Full Text Available Purpose. Investigations of the characteristics of pressure waves presuppose the registration of the total profile of the pressure wave at a given point in space. For these purposes, various types of «pressure to the electrical signal» transmitters (sensors are used. Most of the common sensors are unsuitable for measuring the pulse pressure in a closed water volume at high hydrostatic pressures, in particular to study the effect of a powerful high-voltage pulse discharge on increasing the inflow of minerals and drinking water in wells. The purpose of the work was to develop antijamming piezoelectric waveguide sensor for measuring pulse pressure at a close distance from a high-voltage discharge channel in a closed volume of a liquid. Methodology. We have applied the calibration method as used as a secondary standard, the theory of electrical circuits. Results. We have selected the design and the circuit solution of the waveguide pressure sensor. We have developed a waveguide pulse-pressure sensor DTX-1 with a measuring loop. This sensor makes it possible to study the spectral characteristics of pressure waves of high-voltage pulse discharge in closed volumes of liquid at a hydrostatic pressure of up to 20 MPa and a temperature of up to 80 °C. The sensor can be used to study pressure waves with a maximum amplitude value of up to 150 MPa and duration of up to 80 µs. According to the results of the calibration, the sensitivity of the developed sensor DTX-1 with a measuring loop is 0.0346 V/MPa. Originality. We have further developed the theory of designing the waveguide piezoelectric pulse pressure sensors for measuring the pulse pressure at a close distance from a high-voltage discharge channel in a closed fluid volume by controlling the attenuation of the amplitude of the pressure signal. Practical value. We have developed, created, calibrated, used in scientific research waveguide pressure pulse sensors DTX-1. We propose sensors DTX-1 for sale

  17. An investigation on the physicochemical properties of the nanostructured [(4-X)PMAT][N(CN)2] ion pairs as energetic and tunable aryl alkyl amino tetrazolium based ionic liquids

    Science.gov (United States)

    Khalili, Behzad; Rimaz, Mehdi

    2017-06-01

    In this study the different class of tunable and high nitrogen content ionic liquids termed TAMATILs (Tunable Aryl Methyl Amino Tetrazolium based Ionic Liquids) were designed. The physicochemical properties of the nanostructured TAMATILs composed of para substituted phenyl methyl amino tetrazolium cations [(4-X)PMAT]+ (X = H, Me, OCH3, OH, NH2, NO2, F, CN, CHO, CF3, COMe and CO2Me) and dicyanimide anion [N(CN)2]- were fully investigated using M06-2X functional in conjunction with the 6-311++G(2d,2p) basis set. For all of the studied nanostructured ILs the structural parameters, interaction energy, cation's enthalpy of formation, natural charges, charge transfer values and topological properties were calculated and discussed. The substituent effect on the interaction energy and physicochemical properties also is taking into account. The results showed that the strength of interaction has a linear correlation with electron content of the phenyl ring in a way the substituents with electron withdrawing effects lead to make more stable ion pairs with higher interaction energies. Some of the main physical properties of ILs such as surface tension, melting point, critical-point temperature, electrochemical stability and conductivity are discussed and estimated for studying ion pairs using quantum chemical computationally obtained thermochemical data. Finally the enthalpy and Gibbs free energy of formation for twelve nanostructured individual cations with the general formula of [(4-X)PMAT]+ (X = 4-H, 4-Me, 4-OMe, 4-OH, 4-NH2, 4-NO2, 4-F, 4-CN, 4-CHO, 4-CF3, 4-COMe and 4-CO2Me) are calculated.

  18. Electric-field-induced transport of microspheres in the isotropic and chiral nematic phase of liquid crystals.

    Science.gov (United States)

    Oh, Jiyoung; Gleeson, Helen F; Dierking, Ingo

    2017-02-01

    The application of an electric field to microspheres suspended in a liquid crystal causes particle translation in a plane perpendicular to the applied field direction. Depending on applied electric field amplitude and frequency, a wealth of different motion modes may be observed above a threshold, which can lead to linear, circular, or random particle trajectories. We present the stability diagram for these different translational modes of particles suspended in the isotropic and the chiral nematic phase of a liquid crystal and investigate the angular velocity, circular diameter, and linear velocity as a function of electric field amplitude and frequency. In the isotropic phase a narrow field amplitude-frequency regime is observed to exhibit circular particle motion whose angular velocity increases with applied electric field amplitude but is independent of applied frequency. The diameter of the circular trajectory decreases with field amplitude as well as frequency. In the cholesteric phase linear as well as circular particle motion is observed. The former exhibits an increasing velocity with field amplitude, while decreasing with frequency. For the latter, the angular velocity exhibits an increase with field amplitude and frequency. The rotational sense of the particles on a circular trajectory in the chiral nematic phase is independent of the helicity of the liquid crystalline structure, as is demonstrated by employing a cholesteric twist inversion compound.

  19. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    Science.gov (United States)

    Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G.

    2014-10-01

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4-5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  20. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Bhargavi, R.; Nair, Geetha G., E-mail: geeraj88@gmail.com, E-mail: skpras@gmail.com; Krishna Prasad, S., E-mail: geeraj88@gmail.com, E-mail: skpras@gmail.com [Centre for Nano and Soft Matter Sciences, Jalahalli, Bangalore 560013 (India); Majumdar, R.; Bag, Braja G. [Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore (W) 721 102 (India)

    2014-10-21

    We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.

  1. Chromostereopsis in "virtual reality" adapters with electrically tuneable liquid lens oculars

    Science.gov (United States)

    Ozolinsh, Maris; Muizniece, Kristine; Berzinsh, Janis

    2016-10-01

    Chromostereopsis can be sight and feel in "Virtual Reality" adapters, that induces the appearance of color dependant depth sense and, finally, combines this sense with the source conceived depth scenario. Present studies are devoted to investigation the induced chromastereopsis when using adapted "Virtual Reality" frame together with mobile devices as smartphones. We did observation of composite visual stimuli presented on the high spatial resolution screen of the mobile phone placed inside a portable "Virtual Reality" adapter. Separated for the left and right eyes stimuli consisted of two areas: a) identical for both eyes color chromostereopsis part, and b) additional conventional color neutral random-dot stereopsis part with a stereodisparity based on the horizontal shift of a random-dot segment in images for the left and right eyes, correspondingly. The observer task was to equalize the depth sense for neutral and colored stimuli areas. Such scheme allows to determine actual observed chromostereopsis disparity value versus eye stimuli color difference. At standard observation conditions for adapter with +2D ocular lenses for mobile red-blue stimuli, the perceptual chromostereopsis depth sensitivity on color difference was linearly approximated with a slope SChS ≈ 2.1[arcmin/(Labcolor difference)] for red-blue pairs. Additional to standard application in adapter the tuneable "Varioptic" liquid lens oculars were incorporated, that allowed stimuli eye magnification, vergence and disparity values control electrically.

  2. Novel Tunable Dye Laser for Lidar Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A tunable dye laser for Lidar detection will be fabricated based on the innovative dye-doped Holographic Polymer Dispersed Liquid Crystals (HPDLC) technology. The...

  3. Fast response and transparent optically isotropic liquid crystal diffraction grating.

    Science.gov (United States)

    Manda, Ramesh; Pagidi, Srinivas; Bhattacharyya, Surjya Sarathi; Park, Chul Ho; Lim, Young Jin; Gwag, Jin Seog; Lee, Seung Hee

    2017-10-02

    We have demonstrated an electrically tunable less polarization sensitive and fast response nanostructured polymer dispersed liquid crystal (nano-PDLC) diffraction grating. Fabricated nano-PDLC is optically transparent in visible wavelength regime. The optical isotropic nature was increased by minimizing the liquid crystal droplet size below visible wavelength thereby eliminated scattering. Diffraction properties of in-plane switching (IPS) and fringe-field switching (FFS) cells were measured and compared with one another up to four orders. We have obtained a pore-type polymer network constructed by highly interlinked polymer beads at which the response time is improved by strong interaction of liquid crystal molecules with polymer beads at interface. The diffraction pattern obtained by transparent nano-PDLC film has several interesting properties such as less polarization dependence and fast response. This device can be used as transparent tunable diffractor along with other photonic application.

  4. The influence of the structure of the metal load removal from liquid steel in electric arc furnaces

    Science.gov (United States)

    Pǎcurar, Cristina; Hepuť, Teodor; Crisan, Eugen

    2016-06-01

    One of the main technical and economic indicators in the steel industry and steel respectively the development it is the removal of liquid steel. This indicator depends on several factors, namely technology: the structure and the quality metal load, the degree of preparedness of it, and the content of non-metallic material accompanying the unit of drawing up, the technology for the elaboration, etc. research has been taken into account in drawing up steel electric arc furnace type spring EBT (Electric Bottom taping), seeking to load and removing components of liquid steel. Metal load has been composed of eight metal grades, in some cases with great differences in terms of quality. Data obtained were processed in the EXCEL spreadsheet programs and MATLAB, the results obtained being presented both graphically and analytically. On the basis of the results obtained may opt for a load optimal structure metal.

  5. Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Kuznetsova, Svetlana M.; Zhukovsky, Sergei

    2015-01-01

    We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric...

  6. Self-assembly of colloidal particles in deformation landscapes of electrically driven layer undulations in cholesteric liquid crystals

    OpenAIRE

    Varney, Michael C. M.; Zhang, Qiaoxuan; Senyuk, Bohdan; Smalyukh, Ivan I.

    2016-01-01

    We study elastic interactions between colloidal particles and deformation landscapes of undulations in a cholesteric liquid crystal under an electric field applied normal to cholesteric layers. The onset of undulation instability is influenced by the presence of colloidal inclusions and, in turn, layers' undulations mediate the spatial patterning of particle locations. We find that the bending of cholesteric layers around a colloidal particle surface prompts the local nucleation of an undulat...

  7. A study of the scintillation induced by alpha particles and gamma rays in liquid xenon in an electric field

    OpenAIRE

    Dawson, JV; Howard, AS; Akimov, D.; Araujo, H.; Bewick, A.; Davidge, DCR; Jones, WG; M; Joshi; Lebedenko, VN; Liubarsky, I.; Quenby, JJ; Rochester, G.; Shaul, D; Sumner, TJ; Walker, RJ

    2005-01-01

    Scintillation produced in liquid xenon by alpha particles and gamma rays has been studied as a function of applied electric field. For back scattered gamma rays with energy of about 200 keV, the number of scintillation photons was found to decrease by 64+/-2% with increasing field strength. Consequently, the pulse shape discrimination power between alpha particles and gamma rays is found to reduce with increasing field, but remaining non-zero at higher fields.

  8. Direct measurement of electric-field-induced birefringence in a polymer-stabilized blue-phase liquid crystal composite.

    Science.gov (United States)

    Yan, Jin; Jiao, Meizi; Rao, Linghui; Wu, Shin-Tson

    2010-05-24

    We demonstrate a method to directly measure the electric-field-induced birefringence of a polymer-stabilized blue-phase liquid crystal (PS-BPLC) composite. The induced birefringence follows the extended Kerr effect well and is approximately 3X the ordinary refractive index change. The measured data are validated by comparing the simulated and measured voltage-dependent transmittance with an in-plane switching cell. The impact of these results to the material optimization of emerging BPLC displays is discussed.

  9. Mechanism of electrically induced photonic band gap broadening in polymer stabilized cholesteric liquid crystals with negative dielectric anisotropies.

    Science.gov (United States)

    Nemati, Hossein; Liu, Shiyi; Zola, Rafael S; Tondiglia, Vincent P; Lee, Kyung Min; White, Timothy; Bunning, Timothy; Yang, Deng-Ke

    2015-02-14

    We experimentally observed that the photonic band gap (reflection band) of polymer stabilized cholesteric liquid crystals with negative dielectric anisotropies can be greatly broadened under DC electric fields. We explored the underlying mechanism. We found that the dispersed polymer network moved when DC voltages were applied across the liquid crystal cell. The motion of the polymer network stretched the helical pitch of the liquid crystal on one side of the cell and compressed the helical pitch on the other side of the cell. We proposed a phenomenological theory to explain the motion of the polymer network and the effect of the polymer network on the helical pitch, and this theoretical prediction agreed well with the experimental results.

  10. Activation and control of microlens liquid arrays on functionalized polar electric crystal substrates by electro-wetting effect and temperature

    Science.gov (United States)

    Ferraro, Pietro; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Finizio, Sergio DeNicola Andrea

    2008-11-01

    In recent years a variety of liquid bases optical elements have been conceived, designed and fabricated even for commercial products like digital cameras o cellular phone cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new Science field of investigation named optofludics. Optofludics, among others topics, deals with investigation and methods for realizing liquid micro-lenses. A variety of liquid micro-lenses have been designed and realized by using different configurations. We demonstrate that a lensing effect can be obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal such as Lithium Niobate (LiNbO3). Electrowetting patterning on LiNbO3 surface is obtained by pyroelectric effect consisting in a simple but reliable electrodes-less and circuit-less configuration. The electrodes are intrinsically embedded into the substrate. The material is functionalised by means of a micro-engineering electric filed poling process. Lens array with variable focus has been demonstrated with a large number of lens elements (10x10) on micrometric scale (aperture of single lens 100 microns).

  11. Tunable Nanoplasmonics

    Directory of Open Access Journals (Sweden)

    M. Swillam

    2013-07-01

    Full Text Available In this paper, we present novel mechanisms for tuning and controlling the response of novel plasmonic filter using metal-insulator-metal (MIM configuration. These mechanisms allow for full control on the transmission response from these waveguide based structures. This control can be done electrically or mechanically. The applications and advantages of these novel schemes are discussed in details. Wideband tuning range has been obtained using these schemes.

  12. Liquid-phase exfoliated graphene self-assembled films: Low-frequency noise and thermal-electric characterization

    Energy Technology Data Exchange (ETDEWEB)

    Tubon Usca, G., E-mail: gabriela.tubon@fis.unical.it [Surface Nanoscience Group, Department of Physics, University of Calabria, Via P. Bucci cubo 33C, 87036, Rende, Cosenza (Italy); DIMES - University of Calabria, Via P. Bucci cubo 42C, 87036, Rende, Cosenza (Italy); Hernandez-Ambato, J., E-mail: jhernandez@dimes.unical.it [DIMES - University of Calabria, Via P. Bucci cubo 42C, 87036, Rende, Cosenza (Italy); Pace, C., E-mail: calogero.pace@unical.it [DIMES - University of Calabria, Via P. Bucci cubo 42C, 87036, Rende, Cosenza (Italy); Caputi, L.S., E-mail: lorenzo.caputi@fis.unical.it [Surface Nanoscience Group, Department of Physics, University of Calabria, Via P. Bucci cubo 33C, 87036, Rende, Cosenza (Italy); Tavolaro, A., E-mail: a.tavolaro@itm.cnr.it [Research Institute on Membrane Technology (ITM-CNR), cubo 17C, 87036 University of Calabria, 87036 Rende, Cosenza (Italy)

    2016-09-01

    Highlights: • Graphene was exfoliated in liquid phase also in the presence of zeolite 4A. • Films were obtained by drop-casting. • SEM, Raman, low-frequency noise and thermal electric measurements show that the presence of zeolite improves the quality of the FLG films. - Abstract: In few years, graphene has become a revolutionary material, leading not only to applications in various fields such as electronics, medicine and environment, but also to the production of new types of 2D materials. In this work, Liquid Phase Exfoliation (LPE) was applied to natural graphite by brief sonication or mixer treatment in suitable solvents, in order to produce Few Layers Graphene (FLG) suspensions. Additionally, zeolite 4A (Z4A) was added during the production of FLG flakes-based inks, with the aim of aiding the exfoliation process. Conductive films were obtained by drop casting three types of suspensions over Al{sub 2}O{sub 3} substrates with interdigitated electrodes, with total channel surface of 1.39 mm{sup 2}. The morphology characterization resulted in the verification of the presence of thin self-assembled flakes. Raman studies gave evidence of 4 to 10 layers graphene flakes. Electrical measurements were performed to state the Low-Frequency Noise and Thermal-Electric characteristics of the samples. We observe interesting relations between sample preparation procedures and electrical properties.

  13. Tunable excitons in bilayer graphene

    Science.gov (United States)

    Ju, Long; Wang, Lei; Cao, Ting; Taniguchi, Takashi; Watanabe, Kenji; Louie, Steven G.; Rana, Farhan; Park, Jiwoong; Hone, James; Wang, Feng; McEuen, Paul L.

    2017-11-01

    Excitons, the bound states of an electron and a hole in a solid material, play a key role in the optical properties of insulators and semiconductors. Here, we report the observation of excitons in bilayer graphene (BLG) using photocurrent spectroscopy of high-quality BLG encapsulated in hexagonal boron nitride. We observed two prominent excitonic resonances with narrow line widths that are tunable from the mid-infrared to the terahertz range. These excitons obey optical selection rules distinct from those in conventional semiconductors and feature an electron pseudospin winding number of 2. An external magnetic field induces a large splitting of the valley excitons, corresponding to a g-factor of about 20. These findings open up opportunities to explore exciton physics with pseudospin texture in electrically tunable graphene systems​.

  14. Economic and environmental evaluation of coal-and-biomass-to-liquids-and-electricity plants equipped with carbon capture and storage (data for figures and tables)

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data used in the manuscript's tables and figures. Most data represent the modeled optimal capacity of the coal-and-biomass-to-liquid fuels-and-electricity (CBTLE)...

  15. Electric properties of liquids. Annual progress report, 1 November 1976--31 October 1977

    Energy Technology Data Exchange (ETDEWEB)

    Painter, L.R.

    1977-01-01

    Studies to develop a more accurate method of determining the optical and dielectric properties of liquids and solutions are described. In this method the ionization in the vapor adjacent to the liquid is used to monitor the photon beam strength before and after reflection. The ratio of ion currents is simply related to the reflectance which can, in turn, be analyzed to yield the electronic properties of the liquid. (GHT)

  16. Perovskite Superlattices as Tunable Microwave Devices

    Science.gov (United States)

    Christen, H. M.; Harshavardhan, K. S.

    2003-01-01

    Experiments have shown that superlattices that comprise alternating epitaxial layers of dissimilar paraelectric perovskites can exhibit large changes in permittivity with the application of electric fields. The superlattices are potentially useful as electrically tunable dielectric components of such microwave devices as filters and phase shifters. The present superlattice approach differs fundamentally from the prior use of homogeneous, isotropic mixtures of base materials and dopants. A superlattice can comprise layers of two or more perovskites in any suitable sequence (e.g., ABAB..., ABCDABCD..., ABACABACA...). Even though a single layer of one of the perovskites by itself is not tunable, the compositions and sequence of the layers can be chosen so that (1) the superlattice exhibits low microwave loss and (2) the interfacial interaction between at least two of the perovskites in the superlattice renders either the entire superlattice or else at least one of the perovskites tunable.

  17. 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...... the whole modulation frequency range of 1-15GHz are obtained....

  18. Self-assembly of colloidal particles in deformation landscapes of electrically driven layer undulations in cholesteric liquid crystals

    Science.gov (United States)

    Varney, Michael C. M.; Zhang, Qiaoxuan; Senyuk, Bohdan; Smalyukh, Ivan I.

    2016-10-01

    We study elastic interactions between colloidal particles and deformation landscapes of undulations in a cholesteric liquid crystal under an electric field applied normal to cholesteric layers. The onset of undulation instability is influenced by the presence of colloidal inclusions and, in turn, layers' undulations mediate the spatial patterning of particle locations. We find that the bending of cholesteric layers around a colloidal particle surface prompts the local nucleation of an undulations lattice at electric fields below the well-defined threshold known for liquid crystals without inclusions, and that the onset of the resulting lattice is locally influenced, both dimensionally and orientationally, by the initial arrangements of colloids defined using laser tweezers. Spherical particles tend to spatially localize in the regions of strong distortions of the cholesteric layers, while colloidal nanowires exhibit an additional preference for multistable alignment offset along various vectors of the undulations lattice. Magnetic rotation of superparamagnetic colloidal particles couples with the locally distorted helical axis and undulating cholesteric layers in a manner that allows for a controlled three-dimensional translation of these particles. These interaction modes lend insight into the physics of liquid crystal structure-colloid elastic interactions, as well as point the way towards guided self-assembly of reconfigurable colloidal composites with potential applications in diffraction optics and photonics.

  19. ASSESSMENT OF THE TOTAL SOLIDS AND FAT CONTENTS IN WHOLE LIQUID EGG PRODUCTS BY ELECTRICAL AND THERMAL CONDUCTIVITY MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    Annachiara Berardinelli

    2012-06-01

    Full Text Available The total solids and fat contents of nine whole liquid egg products were assessed by means of electrical and thermal conductivity measurements. Linear correlations between conductivity values and total solids and fat contents were obtained with R2 values up to 0.995 and 0.990 and maximum errors of predic- 46 TABLE 6 - Linear regression models for the total solids (TS, % and fat (FC, % contents estimation from electrical (Ec, mS/cm and thermal (Tc, W/mK conductivity measurements. SE: Standard Error. Linear regression equation R2 p-level SE (% TS=-6.857*Ec+65.373 0.995 0.000 0.27 FC=-4.993*Ec+40.070 0.985 0.000 0.33 TS=-172.967*Tc+109.605 0.992 0.000 0.33 FC=-126.449*Tc+72.521 0.990 0.000 0.27 tion up to 0.41% and 0.42%, respectively. The electrical conductivity of the albumen, yolk and egg mixtures linearly increased with temperature; at 20°C, temperature coefficients of 2.1%/°C, 2.1%/°C and 1.9 %/°C were respectively calculated. On the contrary, the thermal conductivity of the analysed products did not appear to be substantially influenced by the temperature of the liquid.

  20. Tunable microwave metamaterial absorbers using varactor-loaded split loops

    Science.gov (United States)

    Zhu, Jinfeng; Li, Delong; Yan, Shuang; Cai, Yijun; Huo Liu, Qing; Lin, Timothy

    2015-12-01

    Currently, implementation of active circuit elements within metamaterials is an effective way to make them electrically tunable. We combine varactors with split copper loops in a metamaterial absorber in order to obtain an electrically tunable microwave response. This absorber has a compact planar structure and a simplified back feeding network. Flexible frequency tunability of the microwave reflection in the range of 5-6 GHz is experimentally achieved. The design, simulation, and experimental results are systematically presented. The proposed method is scalable for developing active metamaterial absorbers based on metal loops, and shows a promising potential of active metamaterial absorbers for extensive microwave applications.

  1. Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

    Energy Technology Data Exchange (ETDEWEB)

    Loiko, V. A., E-mail: loiko@ifanbel.bas-net.by; Konkolovich, A. V. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus); Zyryanov, V. Ya. [Russian Academy of Sciences, Kirensky Institute of Physics, Federal Research Center “Krasnoyarsk Scientific Center,” Siberian Branch (Russian Federation); Miskevich, A. A. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)

    2017-03-15

    We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet–polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing the volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ{sub s} and–θ{sub s} relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal–polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.

  2. Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

    Science.gov (United States)

    Loiko, V. A.; Konkolovich, A. V.; Zyryanov, V. Ya.; Miskevich, A. A.

    2017-03-01

    We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet-polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing the volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ s and-θ s relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal-polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.

  3. Highly Tunable Electrostatic Nanomechanical Resonators

    KAUST Repository

    Kazmi, Syed Naveed Riaz

    2017-11-24

    There has been significant interest towards highly tunable resonators for on-demand frequency selection in modern communication systems. Here, we report highly tunable electrostatically actuated silicon-based nanomechanical resonators. In-plane doubly-clamped bridges, slightly curved as shallow arches due to residual stresses, are fabricated using standard electron beam lithography and surface nanomachining. The resonators are designed such that the effect of mid-plane stretching dominates the softening effect of the electrostatic force. This is achieved by controlling the gap-to-thickness ratio and by exploiting the initial curvature of the structure from fabrication. We demonstrate considerable increase in the resonance frequency of nanoresonators with the dc bias voltages up to 108% for 180 nm thick structures with a transduction gap of 1 $mu$m separating them from the driving/sensing electrodes. The experimental results are found in good agreement with those of a nonlinear analytical model based on the Euler-Bernoulli beam theory. As a potential application, we demonstrate a tunable narrow band-pass filter using two electrically coupled nanomechanical arch resonators with varied dc bias voltages.

  4. Tunable plasmonic crystal

    Science.gov (United States)

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  5. Tunable laser applications

    CERN Document Server

    Duarte, FJ

    2008-01-01

    Introduction F. J. Duarte Spectroscopic Applications of Tunable Optical Parametric Oscillators B. J. Orr, R. T. White, and Y. He Solid-State Dye Lasers Costela, I. García-Moreno, and R. Sastre Tunable Lasers Based on Dye-Doped Polymer Gain Media Incorporating Homogeneous Distributions of Functional Nanoparticles F. J. Duarte and R. O. James Broadly Tunable External-Cavity Semiconductor Lasers F. J. Duarte Tunable Fiber Lasers T. M. Shay and F. J. Duarte Fiber Laser Overview and Medical Applications

  6. Microelectromechanical tunable inductor

    Science.gov (United States)

    Stalford, Harold L [Norman, OK; Hietala, Vincent M [Albuquerque, NM; Fleming, James G [Albuquerque, NM; Fleming, legal representative, Carol

    2010-05-04

    A microelectromechanical tunable inductor is formed from a pair of substantially-identically-sized coils arranged side by side and coiled up about a central axis which is parallel to a supporting substrate. An in-plane stress gradient is responsible for coiling up the coils which. The inductance provided by the tunable inductor can be electrostatically changed either continuously or in discrete steps using electrodes on the substrate and on each coil. The tunable inductor can be formed with processes which are compatible with conventional IC fabrication so that, in some cases, the tunable inductor can be formed on a semiconductor substrate alongside or on top of an IC.

  7. Machining and Surface Characteristics of AISI 304L After Electric Discharge Machining for Copper and Graphite Electrodes in Different Dielectric Liquids

    Directory of Open Access Journals (Sweden)

    S. Anjum

    2017-08-01

    Full Text Available In Electric Discharge Machining (EDM, the thermal energy used for material erosion depends on the intensity of electric sparks, the thermal conductivities of electrode material and the dielectric liquid. In this paper, the effect of EDM on AISI 304L steel is studied using copper and graphite electrodes and distilled water and kerosene oil as dielectric liquids. Material Removal Rates (MRR, Tool Wear Rates (TWR and surface conditions are calculated for four different combinations with the two electrode materials and the two dielectric liquids. These investigations are carried out at different pulse currents. Machined surfaces are evaluated by morphological studies, energy dispersive spectrographs (EDS and white layer thickness using Scanning Electron Microscopy (SEM. It is found that a transfer of carbon takes place from the kerosene oil and the graphite electrodes into the machined surface which alters the metallurgical characteristics, depending on the electrical and thermal conductivities of the electrode material and the dielectric liquid.

  8. Coarse-grained simulations for organic molecular liquids based on Gay-Berne and electric multipole potentials.

    Science.gov (United States)

    Xu, Peijun; Shen, Hujun; Yang, Lu; Ding, Yang; Li, Beibei; Shao, Ying; Mao, Yingchen; Li, Guohui

    2013-02-01

    Coarse-grained studies of CH(3)SH, CH(3)CHO and CHCl(3) liquids, based on anisotropic Gay-Berne (GB) and electric multipole potentials (EMP), demonstrate that the coarse-grained model is able to qualitatively reproduce the results obtained from the atomistic model (AMOEBA polarizable force field) and allows for significant saving in computation time. It should be pointed out that the accuracy of the coarse-grained model is very sensitive to how well the anisotropic GB particle is defined and how satisfactorily the EMP sites are chosen.

  9. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

    Directory of Open Access Journals (Sweden)

    Amid Ranjkesh

    2015-12-01

    Full Text Available We propose a highly oriented photochromic dye film for an ultraviolet (UV-sensing layer, where spirooxazine (SO derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation.

  10. Electrically switchable cylindrical Fresnel lens based on holographic polymer-dispersed liquid crystals using a Michelson interferometer

    CERN Document Server

    Jashnsaz, Hossein; Nataj, Nahid Hosain

    2016-01-01

    Fabricating an electrically switchable cylindrical Fresnel lens based on holographic polymer-dispersed liquid crystals (H-PDLC) using a Michelson interferometer is reported. Simplicity of the method and possibility of fabricating different focal length lenses in a single set up are among the advantages of the method. It is demonstrated that the Fresnel structured zone plate acts as a cylindrical lens and focuses light in one dimension. Its electro-optical switching properties are also studied and it is found that at an applied electric field of E=6 Vrms/{\\mu}m across the sample, focusing property of the sample eliminates with a response of about 1 ms in a reversible manner.

  11. Tunable Nano-photonic Devices

    Science.gov (United States)

    Das, Susobhan

    For high speed photonic systems and networks, encoding electronic signal onto optical carrier. requires electro-optic modulators in which electromagnetic fields of the optical carrier can be. manipulated electronically. The central focus of this research is twofold. First, tunable properties. and tuning mechanisms of different optical materials like Graphene, Vanadium di-oxide, and. Indium Tin Oxide are characterized systematically in telecommunication wavelength region. Then, these materials are implemented to design novel nano-photonic devices such as electrooptic. modulators and tunable couplers with high efficiency and miniature footprint suitable for. photonic integration. Specifically, we experimentally investigated the complex index of graphene in near infrared. wavelength through the reflectivity measurement on a SiO2/Si substrate. The measured change. of reflectivity as the function of applied gate voltage is highly correlated with theoretical. modeling based on the Kubo formula. Based on a fiber-optic pump-probe setup we demonstrated. that short optical pulses can be translated from pump wavelength to probe wavelength through. dielectric-to-metal phase transition of vanadium di-oxide. In this process, pump leading edge. induced optical phase modulation on the probe is converted into an intensity modulation through. an optical frequency discriminator. We also theoretically modeled the permittivity of Indium. Tin-Oxide with different level of doping concentration in near infrared region. We proposed an ultra-compact electro-optic modulator based on switching plasmonic resonance. “ON” and “OFF” of ITO-on-graphene via tuning of graphene chemical potential through. electrical gating. The plasmonic resonance of ITO-on-graphene significantly enhances the. electromagnetic field interaction with graphene which allows the reduction of modulator size. compare to graphene based modulators without ITO. We presented a scheme of modeiv. multiplexed near infrared

  12. Liquid Crystals and Photonic Bandgap Fiber Components

    DEFF Research Database (Denmark)

    Weirich, Johannes; Wei, Lei; Scolari, Lara

    Liquid Crystal(LC)filled Photonic Crystal Fibers(PCFs) represent a promising platform for the design and the fabrication of tunable all-in fiber devices. Tunability is achieved by varying the refractive index of the LC thermally, optically or electrically. In this contribution we present important...... parts of the LC theory as well as an application of a LC infiltrated PCF subject to an external electrostatic field. The fiber is placed between two electrodes and the voltage is increased step by step leading to the reorientation of the LC in the fiber capillaries. This mechanism can be used to produce...... a swichable polarizer, and an on chip LC photonic bandgap fiber polarimeter is presented, which admits strong attenuation of one polarization direction while the other one is nearly unaffected....

  13. Tunable Terahertz Hybrid Metal-Graphene Plasmons.

    Science.gov (United States)

    Jadidi, Mohammad M; Sushkov, Andrei B; Myers-Ward, Rachael L; Boyd, Anthony K; Daniels, Kevin M; Gaskill, D Kurt; Fuhrer, Michael S; Drew, H Dennis; Murphy, Thomas E

    2015-10-14

    We report here a new type of plasmon resonance that occurs when graphene is connected to a metal. These new plasmon modes offer the potential to incorporate a tunable plasmonic channel into a device with electrical contacts, a critical step toward practical graphene terahertz optoelectronics. Through theory and experiments, we demonstrate, for example, anomalously high resonant absorption or transmission when subwavelength graphene-filled apertures are introduced into an otherwise conductive layer. These tunable plasmon resonances are essential yet missing ingredients needed for terahertz filters, oscillators, detectors, and modulators.

  14. Vibrational Stark Effect to Probe the Electric-Double Layer of the Ionic Liquid-Metal Electrodes

    Science.gov (United States)

    Garcia Rey, Natalia; Moore, Alexander Knight; Toyouchi, Shuichi; Dlott, Dana

    2017-06-01

    Vibrational sum frequency generation (VSFG) spectroscopy is used to study the effect of room temperature ionic liquids (RTILs) in situ at the electrical double layer (EDL). RTILs have been recognized as electrolytes without solvent for applications in batteries, supercapacitors and electrodeposition^{1}. The molecular response of the RTIL in the EDL affects the performance of these devices. We use the vibrational Stark effect on CO as a probe to detect the changes in the electric field affected by the RTIL across the EDL on metal electrodes. The Stark effect is a shift in the frequency in response to an externally applied electric field and also influenced by the surrounding electrolyte and electrode^{2}. The CO Stark shift is monitored by the CO-VSFG spectra on Pt or Ag in a range of different imidazolium-based RTILs electrolytes, where their composition is tuned by exchanging the anion, the cation or the imidazolium functional group. We study the free induction decay (FID)^{3} of the CO to monitor how the RTIL structure and composition affect the vibrational relaxation of the CO. Combining the CO vibrational Stark effect and the FID allow us to understand how the RTIL electrochemical response, molecular orientation response and collective relaxation affect the potential drop of the electric field across the EDL, and, in turn, how determines the electrical capacitance or reactivity of the electrolyte/electrode interface. ^{1}Fedorov, M. V.; Kornyshev, A. A., Ionic Liquids at Electrified Interfaces. Chem. Rev. 2014, 114, 2978-3036. ^{2} (a) Lambert, D. K., Vibrational Stark Effect of Adsorbates at Electrochemical Interfaces. Electrochim. Acta 1996, 41, 623-630. (b) Oklejas, V.; Sjostrom, C.; Harris, J. M., SERS Detection of the Vibrational Stark Effect from Nitrile-Terminated SAMs to Probe Electric Fields in the Diffuse Double-Layer. J. Am. Chem. Soc. 2002, 124, 2408-2409. ^{3}Symonds, J. P. R.; Arnolds, H.; Zhang, V. L.; Fukutani, K.; King, D. A

  15. MEMS Tunable Antennas

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2014-01-01

    Addressing low frequency bands is challenging on small platforms. Tunability is a promising solution to cover the bandwidth required for 4G mobile communication. The work presents two designs and shows that for comparable efficiency and bandwidth, the tunable antenna occupies half the volume...... required by the wide-band antenna....

  16. Dependence on the electric power of the immersion-angle dependence of the resonant-frequency shift of a quartz crystal microbalance in a liquid.

    Science.gov (United States)

    Yoshimoto, Minoru; Maruyama, Yasuhiro; Kurosawa, Shigeru; Kanazawa, K Keiji

    2007-04-18

    We have investigated the immersion-angle dependence of the series resonant-frequency shift, DeltaF, of the quartz crystal microbalance, QCM, in a Newtonian liquid from the point of view of the supplied electric power level. In the low electric power levels, the immersion-angle dependence and the transition phenomenon of the DeltaF are observed. However, when the higher electric power levels are supplied to the QCM, the region of the transition phenomenon of the DeltaF decreases rapidly with an increase in the electric power level and disappears above 1.5 dBm. That is, above 1.5 dBm, the DeltaF values have only the values of 90 degrees immersion angle in all immersion angles. We suggest that the electric power is very important factor for the DeltaF in a liquid.

  17. Model and Simulation of a Tunable Birefringent Fiber Using Capillaries Filled with Liquid Ethanol for Magnetic Quasiphase Matching In-Fiber Isolator

    Directory of Open Access Journals (Sweden)

    Clint Zeringue

    2010-01-01

    Full Text Available A technique to tune a magnetic quasi-phase matching in-fiber isolator through the application of stress induced by two mutually orthogonal capillary tubes filled with liquid ethanol is investigated numerically. The results show that it is possible to “tune” the birefringence in these fibers over a limited range depending on the temperature at which the ethanol is loaded into the capillaries. Over this tuning range, the thermal sensitivity of the birefringence is an order-of-magnitude lower than conventional fibers, making this technique well suited for magnetic quasi-phase matching.

  18. Gate-tunable conducting oxide metasurfaces

    CERN Document Server

    Huang, Yao-Wei; Sokhoyan, Ruzan; Pala, Ragip; Thyagarajan, Krishnan; Han, Seunghoon; Tsai, Din Ping; Atwater, Harry A

    2015-01-01

    Metasurfaces composed of planar arrays of sub-wavelength artificial structures show promise for extraordinary light manipulation; they have yielded novel ultrathin optical components such as flat lenses, wave plates, holographic surfaces and orbital angular momentum manipulation and detection over a broad range of electromagnetic spectrum. However the optical properties of metasurfaces developed to date do not allow for versatile tunability of reflected or transmitted wave amplitude and phase after fabrication, thus limiting their use in a wide range of applications. Here, we experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in a reflectarray geometry. We measure a phase shift of {\\pi} and ~ 30% change in the reflectanc...

  19. Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, D.C.

    1986-10-08

    Measurements are reported for the electrical conductivity of liquid nitrogen (N/sub 2/), oxygen (O/sub 2/) and benzene (C/sub 6/H/sub 6/), and Hugoniot equation of state of liquid 1-butene (C/sub 4/H/sub 8/) under shock compressed conditions. The conductivity data span 7 x 10/sup -4/ to 7 x 10/sup 1/ ..cap omega../sup -1/cm/sup -1/ over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs.

  20. Electricity generation and nutrients removal from high-strength liquid manure by air-cathode microbial fuel cells.

    Science.gov (United States)

    Lin, Hongjian; Wu, Xiao; Nelson, Chad; Miller, Curtis; Zhu, Jun

    2016-01-01

    Air-cathode microbial fuel cells (MFCs) are widely tested to recover electrical energy from waste streams containing organic matter. When high-strength wastewater, such as liquid animal manure, is used as a medium, inhibition on anode and cathode catalysts potentially impairs the effectiveness of MFC performance in power generation and pollutant removal. This study evaluated possible inhibitive effects of liquid swine manure components on MFC power generation, improved liquid manure-fed MFCs performance by pretreatment (dilution and selective adsorption), and modeled the kinetics of organic matter and nutrients removal kinetics. Parameters monitored included pH, conductivity, chemical oxygen demand (COD), volatile fatty acids (VFAs), total ammoniacal nitrogen (TAN), nitrite, nitrate, and phosphate concentrations. The removals of VFA and TAN were efficient, indicated by the short half-life times of 4.99 and 7.84 d, respectively. The mechanism for phosphate decrease was principally the salt precipitation on cathode, but the removal was incomplete after 42-d operation. MFC with an external resistor of 2.2 kΩ and fed with swine wastewater generated relatively small power (28.2 μW), energy efficiency (0.37%) and Coulombic efficiency (1.5%). Dilution of swine wastewater dramatically improved the power generation as the inhibitory effect was decreased. Zeolite and granular activated carbon were effective in the selective adsorption of ammonia or organic matter in swine wastewater, and so substantially improved the power generation, energy efficiency, and Coulombic efficiency. A smaller external resistor in the circuit was also observed to promote the organic matter degradation and thus to shorten the treatment time. Overall, air-cathode MFCs are promising for generating electrical power from livestock wastewater and meanwhile reducing the level of organic matter and nutrients.

  1. Transformations of Liquid Metals in Ionic Liquid

    OpenAIRE

    Liu, Fujun; Yu, Yongze; Liu, Jing

    2017-01-01

    Experimental studies were carried out on the motions and transformations of liquid metal in ionic liquid under applied electric field. The induced vortex rings and flows of ionic liquid were determined via the photographs taken sequentially over the experiments. The polarization of electric double layer of liquid metals was employed to explain the flow of ionic liquid with the presence of liquid metal. Unlike former observation of liquid metal machine in conventional solution, no gas bubble w...

  2. The effect of liquid target on a nonthermal plasma jet—imaging, electric fields, visualization of gas flow and optical emission spectroscopy

    Science.gov (United States)

    Kovačević, Vesna V.; Sretenović, Goran B.; Slikboer, Elmar; Guaitella, Olivier; Sobota, Ana; Kuraica, Milorad M.

    2018-02-01

    The article describes the complex study of the interaction of a helium plasma jet with distilled water and saline. The discharge development, spatial distribution of the excited species, electric field measurement results and the results of the Schlieren imaging are presented. The results of the experiments showed that the plasma–liquid interaction could be prolonged with the proper choice of the gas composition between the jet nozzle and the target. This depends on the gas flow and the target distance. Increased conductivity of the liquid does not affect the discharge properties significantly. An increase of the gas flow enables an extension of the plasma duration on the liquid surface up to 10 µs, but with a moderate electric field strength in the ionization wave. In contrast, there is a significant enhancement of the electric field on the liquid surface, up to 30 kV cm‑1 for low flows, but with a shorter time of the overall plasma liquid interaction. Ignition of the plasma jet induces a gas flow modification and may cause turbulences in the gas flow. A significant influence of the plasma jet causing a mixing in the liquid is also recorded and it is found that the plasma jet ignition changes the direction of the liquid circulation.

  3. Ionic liquid ferrofluid interface deformation and spray onset under electric and magnetic stresses

    Science.gov (United States)

    Jackson, Brandon A.; Terhune, Kurt J.; King, Lyon B.

    2017-06-01

    An experimental and computational study is presented on the interfacial dynamics of a colloidal fluid having both high electric conductivity and high magnetic permeability in the presence of simultaneous electric and magnetic stresses on the fluid/air interface. A transient computational model is developed that simultaneously solves the Navier-Stokes equation and Maxwells' static equations to predict the transient geometry of the fluid subject to electric and magnetic stresses. This model is first applied to predict the onset of spray emission from a capillary needle electrospray source subjected to a magnetic field. The experimentally determined onset of emissions at each magnetic field agreed well with those predicted by the simulation tool. The predictive modeling tool was then applied to analyze the interfacial profile of a sessile droplet subjected to both electric and magnetic fields. The model captured the geometric evolution of the droplet for voltages up to approximately 85% of the critical onset voltage; near the onset, the model slightly overpredicted the droplet deformation. Using the interfacial stress obtained from the modeling tool, a quantitative discussion is made regarding the roles and magnitudes of the electric and magnetic stress components on the lead-up to the emission instability.

  4. Liquid-phase exfoliated graphene self-assembled films: Low-frequency noise and thermal-electric characterization

    Science.gov (United States)

    Tubon Usca, G.; Hernandez-Ambato, J.; Pace, C.; Caputi, L. S.; Tavolaro, A.

    2016-09-01

    In few years, graphene has become a revolutionary material, leading not only to applications in various fields such as electronics, medicine and environment, but also to the production of new types of 2D materials. In this work, Liquid Phase Exfoliation (LPE) was applied to natural graphite by brief sonication or mixer treatment in suitable solvents, in order to produce Few Layers Graphene (FLG) suspensions. Additionally, zeolite 4A (Z4A) was added during the production of FLG flakes-based inks, with the aim of aiding the exfoliation process. Conductive films were obtained by drop casting three types of suspensions over Al2O3 substrates with interdigitated electrodes, with total channel surface of 1.39 mm2. The morphology characterization resulted in the verification of the presence of thin self-assembled flakes. Raman studies gave evidence of 4 to 10 layers graphene flakes. Electrical measurements were performed to state the Low-Frequency Noise and Thermal-Electric characteristics of the samples. We observe interesting relations between sample preparation procedures and electrical properties.

  5. Spiral phase plate based on polymer dispersed liquid crystal for wide visible band applications.

    Science.gov (United States)

    Wu, Shing-Trong; Fuh, Andy Ying-Guey

    2014-09-01

    This study demonstrates helical wave fronts via a spiral phase plate based on polymer dispersed liquid crystals (PDLCs). Because the PDLC is electric tunable, the plate can be used in a wide visible band. In addition, if the probe beam deviates from the center of the sample, some of the light propagates out of the sectors. We propose some of the applications for the results.

  6. Electrical resistivity of NaPb compound-forming liquid alloy using ab ...

    Indian Academy of Sciences (India)

    Complex formation model [17,18] has its basis on the fact that a typical binary liquid alloy forms a compound at one or more stoichiometric compositions and therefore behaves like a ternary mixture consisting of free atoms A, B and a chemical compound or pseudomolecule AαBβ such that αA + βB = AαBβ. There are nA.

  7. NATO Advanced Study Institute International Advanced Course on The Liquid State and Its Electrical Properties

    CERN Document Server

    Christophorou, L; Luessen, L

    1988-01-01

    As the various disciplines of science advance, they proliferate and tend to become more esoteric. Barriers of specialized terminologies form, which cause scientists to lose contact with their colleagues, and differences in points-of-view emerge which hinder the unification of knowledge among the various disciplines, and even within a given discipline. As a result, the scientist, and especially the student, is in many instances offered fragmented glimpses of subjects that are funda­ mentally synthetic and that should be treated in their own right. Such seems to be the case of the liquid state. Unlike the other states of matter -- gases, solids, and plasmas -- the liquid state has not yet received unified treatment, probably because it has been the least explored and remains the least understood state of matter. Occasionally, events occur which help remove some of the barriers that separate scientists and disciplines alike. Such an event was the ASI on The Liquid State held this past July at the lovely Hotel T...

  8. Bilayers of Ni3C12S12 and Pt3C12S12: graphene-like 2D topological insulators tunable by electric fields

    Science.gov (United States)

    Silveira, Orlando J.; Lima, Érika N.; Chacham, Hélio

    2017-11-01

    In the present work we predict, through first-principles calculations, that bilayers of the recently synthesized Ni3 C12 S12 and Pt3 C12 S12 layered materials are topological insulators upon electron doping, and that their topological insulator properties can be modulated by the application of electric fields with magnitudes achievable in devices. The electronic structures of both bilayers are characterized by spin–orbit split graphene-like bands, with gap magnitudes that are three orders of magnitude larger than graphene’s. In ribbon geometries, chiral edge modes develop at each side with band dispersions similar to that of Kane–Mele graphene model. Surprisingly, the edge states’ spin-propagation locking occurs even for very thin ribbons. We also find that the response of the electronic structure of both materials to applied electric fields are similar to both graphene and the Kane–Mele model with a Rashba term. All these findings indicate that these bilayer systems can be considered as large-spin–orbit graphene analogues with a strong sensitivity to applied electric fields.

  9. Instability of electrically-driven MHD flow in a modified cylindrical annulus filled with liquid GaInSn

    Science.gov (United States)

    Stelzer, Zacharias; Miralles, Sophie; Cébron, David; Vantieghem, Stijn; Noir, Jérôme; Jackson, Andrew

    2014-05-01

    Planetary magnetic fields such as that of the Earth are thought to be generated by motions of electrically conducting fluids and can be described by the theory of magnetohydrodynamics (MHD). Liquid cores of such astrophysical bodies are dominated by Coriolis and Lorentz forces. Instabilities developing in this magnetostrophic regime are poorly known, numerical studies being far from the actual parameters. We study the destabilization of a flow of liquid GaInSn in a modified cylindrical annulus experimentally and numerically. The flow is driven by the Lorentz force resulting from the injection of a radial electrical current under an imposed axial magnetic field. The novel feature compared to previous studies with similar geometry [Moresco and Alboussière, JFM, 2004] is the form of the electrodes, the inner one being a disk electrode, the outer one a ring electrode. A shear layer, termed the Shercliff layer, develops at the edge of the disk electrode. Using magnetic fields up to 1 T and forcing currents up to 150 A, we reach Hartmann numbers up to 2000 and Reynolds numbers of the order of 10 ^ 5 which are hardly accessible in numerical simulations. We measure the liquid-metal motions by ultrasonic Doppler velocimetry and potential differences. We characterize the flow in terms of a mean flow and fluctuations. Initiating from the Shercliff layer at low forcing currents, we observe mainly monochromatic oscillations that grow in frequency and space with increasing forcing current and magnetic field strength. The threshold of instabilities is dependent on the field strength. For the regime of low Hartmann and Reynolds numbers, we also perform numerical simulations of the flow in our setup using the quasi-static approximation. With 2.5 D finite element modelling, we are able to track the threshold of linear stability for the base flow. First results coincide well with the observations from the lab experiment. Future experiments are currently developed to further

  10. Tunable Handset Antenna

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Foroozanfard, Ehsan; Morris, Art

    2017-01-01

    With the future LTE auction for TV white spaces at 600 MHz, there is a strong need for efficient handset antennas operating at very low frequencies. This paper shows a tunable antenna covering the LTE bands from 600 MHz to 2.6 GHz. The antenna uses state-of-the-art MEMS tunable capacitors in order...... to reconfigure its operating frequency. In this work, the design mitigates the tuning loss with a tunable extended ground plane. The resulting dual-resonant antenna exhibits a peak total efficiency of -3.9 dB at 600 MHz....

  11. Tunable Handset Antenna

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Foroozanfard, Ehsan; Morris, Art

    2017-01-01

    With the future LTE auction for TV white spaces at 600 MHz, there is a strong need for efficient handset antennas operating at very low frequencies. This paper shows a tunable antenna covering the LTE bands from 600 MHz to 2.6 GHz. The antenna uses state-of-the-art MEMS tunable capacitors in orde...... to reconfigure its operating frequency. In this work, the design mitigates the tuning loss with a tunable extended ground plane. The resulting dual-resonant antenna exhibits a peak total efficiency of -3.9 dB at 600 MHz....

  12. Electrical signatures of ethanol-liquid mixtures: implications for monitoring biofuels migration in the subsurface

    Science.gov (United States)

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    Ethanol (EtOH), an emerging contaminant with potential direct and indirect environmental effects, poses threats to water supplies when spilled in large volumes. A series of experiments was directed at understanding the electrical geophysical signatures arising from groundwater contamination by ethanol. Conductivity measurements were performed at the laboratory scale on EtOH–water mixtures (0 to 0.97 v/v EtOH) and EtOH–salt solution mixtures (0 to 0.99 v/v EtOH) with and without a sand matrix using a conductivity probe and a four-electrode electrical measurement over the low frequency range (1–1000 Hz). A Lichtenecker–Rother (L–R) type mixing model was used to simulate electrical conductivity as a function of EtOH concentration in the mixture. For all three experimental treatments increasing EtOH concentration resulted in a decrease in measured conductivity magnitude (|σ|). The applied L–R model fitted the experimental data at concentration ≤ 0.4 v/v EtOH, presumably due to predominant and symmetric intermolecular (EtOH–water) interaction in the mixture. The deviation of the experimental |σ| data from the model prediction at higher EtOH concentrations may be associated with hydrophobic effects of EtOH–EtOH interactions in the mixture. The |σ| data presumably reflected changes in relative strength of the three types of interactions (water–water, EtOH–water, and EtOH–EtOH) occurring simultaneously in EtOH–water mixtures as the ratio of EtOH to water changed. No evidence of measurable polarization effects at the EtOH–water and EtOH–water–mineral interfaces over the investigated frequency range was found. Our results indicate the potential for using electrical measurements to characterize and monitor EtOH spills in the subsurface.

  13. Modular Serial Flow Through device for pulsed electric field treatment of the liquid samples.

    Science.gov (United States)

    Kandušer, Maša; Belič, Aleš; Čorović, Selma; Škrjanc, Igor

    2017-08-14

    In biotechnology, medicine, and food processing, simple and reliable methods for cell membrane permeabilization are required for drug/gene delivery into the cells or for the inactivation of undesired microorganisms. Pulsed electric field treatment is among the most promising methods enabling both aims. The drawback in current technology is controllable large volume operation. To address this challenge, we have developed an experimental setup for flow through electroporation with online regulation of the flow rate with feedback control. We have designed a modular serial flow-through co-linear chamber with a smooth inner surface, the uniform cross-section geometry through the majority of the system's length, and the mesh in contact with the electrodes, which provides uniform electric field distribution and fluid velocity equilibration. The cylindrical cross-section of the chamber prevents arching at the active treatment region. We used mathematical modeling for the evaluation of electric field distribution and the flow profile in the active region. The system was tested for the inactivation of Escherichia coli. We compared two flow-through chambers and used a static chamber as a reference. The experiments were performed under identical experimental condition (product and similar process parameters). The data were analyzed in terms of inactivation efficiency and specific energy consumption.

  14. Synthesis of Ag3PO4 Crystals with Tunable Shapes for Facet-Dependent Optical Property, Photocatalytic Activity, and Electrical Conductivity Examinations.

    Science.gov (United States)

    Hsieh, Meng-Shan; Su, Huang-Jen; Hsieh, Pei-Lun; Chiang, Yun-Wei; Huang, Michael H

    2017-11-08

    This work has developed conditions for the synthesis of Ag3PO4 cubes, rhombic dodecahedra, {100}-truncated rhombic dodecahedra, tetrahedra, and tetrapods by tuning the amount of NH4NO3, NaOH, AgNO3, and K2HPO4 solutions added. Use of a minimal amount of AgNO3 solution can form much smaller rhombic dodecahedra and tetrahedra. Submicrometer-sized Ag3PO4 cubes and rhombic dodecahedra with sizes larger than 300 nm do not exhibit the optical size effect, but ∼290 nm rhombic dodecahedra show a smaller band gap value than larger cubes, and tetrahedra show the most blue-shifted absorption edge. The optical facet effect is present in Ag3PO4 crystals. Ag3PO4 cubes are more photocatalytically active than rhombic dodecahedra toward photodegradation of methyl orange, but tetrahedra are inactive, showing clear presence of photocatalytic facet effects. Electron paramagnetic resonance results confirm much higher production of hydroxyl radicals from photoirradiated Ag3PO4 cubes than from rhombic dodecahedra, while tetrahedra yield essentially no radicals. A modified band diagram showing different degrees of band edge bending can explain these observations. All these Ag3PO4 crystals show poor electrical conductivity properties, but the {110} faces are slightly more conductive than the {100} faces. As a result, current rectifying I-V curves have been obtained, demonstrating that facet-dependent electrical properties are broadly observable in many semiconductor materials. This work reveals again that facet-dependent optical, photocatalytic, and electrical conductivity properties are intrinsic semiconductor properties.

  15. Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials.

    Science.gov (United States)

    Andryieuski, Andrei; Kuznetsova, Svetlana M; Zhukovsky, Sergei V; Kivshar, Yuri S; Lavrinenko, Andrei V

    2015-08-27

    We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric resonances in a metamaterial consisting of periodically positioned water-filled reservoirs. The proposed water-based metamaterials can find applications not only as cheap and ecological microwave devices, but also in optical and terahertz metamaterials prototyping and educational lab equipment.

  16. Electrical Properties of Zn-Phthalocyanine and Poly (3-hexylthiophene Doped Nematic Liquid Crystal

    Directory of Open Access Journals (Sweden)

    Y. Karakuş

    2011-01-01

    Full Text Available An E7 coded nematic liquid crystal was doped with zinc phthalocyanine and poly (3-hexylthiophene. A variety of properties including relaxation time, absorption coefficient, and critical frequency of this doped system were investigated using impedance spectroscopy. The doped systems displayed increased absorption coefficients in the range 0.22–0.55 and relaxation times from 5.05×10−7 s to 3.59×10−6 s with a decrease in the critical frequency from 3.54 MHz to 2.048 MHz.

  17. Electrically Rotatable Polarizer Using One-Dimensional Photonic Crystal with a Nematic Liquid Crystal Defect Layer

    Directory of Open Access Journals (Sweden)

    Ryotaro Ozaki

    2015-09-01

    Full Text Available Polarization characteristics of defect mode peaks in a one-dimensional (1D photonic crystal (PC with a nematic liquid crystal (NLC defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD simulation.

  18. Tunable micro-optics

    CERN Document Server

    Duppé, Claudia

    2015-01-01

    Presenting state-of-the-art research into the dynamic field of tunable micro-optics, this is the first book to provide a comprehensive survey covering a varied range of topics including novel materials, actuation concepts and new imaging systems in optics. Internationally renowned researchers present a diverse range of chapters on cutting-edge materials, devices and subsystems, including soft matter, artificial muscles, tunable lenses and apertures, photonic crystals, and complete tunable imagers. Special contributions also provide in-depth treatment of micro-optical characterisation, scanners, and the use of natural eye models as inspiration for new concepts in advanced optics. With applications extending from medical diagnosis to fibre telecommunications, Tunable Micro-optics equips readers with a solid understanding of the broader technical context through its interdisciplinary approach to the realisation of new types of optical systems. This is an essential resource for engineers in industry and academia,...

  19. Liquid Crystal photonic Bandgap Fiber Devices

    DEFF Research Database (Denmark)

    Wei, Lei

    and electrically controlled to work both as a quarter-wave plate or half-wave plate. An electrically tunable bandpass filter based on two solid-core PCFs filled with different LCs is fabricated, and the tunability of the bandwidth is achieved by individually or simultaneously controlling the driving voltage...... presents bandgaps. These bandgaps can be tuned by applying an electric field or by varying the temperature. Therefore, tunable all-in-fiber devices with controllable optical properties can be realized. This thesis focuses on the design, fabrication and development of com-pact LCPBG fiber devices. An on....... A polarizer with electrically tunable polarization extinction ratio is obtained. An on-chip tunable notch filter based on long-period gratings is presented, exhibiting high polarization sensitivity. A tunable polarization controller using negative dielectric LCs is developed, which can be thermally...

  20. Magneto-thermally activated spin-state transition in La0.95Ca0.05CoO3: magnetically-tunable dipolar glass and giant magneto-electricity.

    Science.gov (United States)

    Pandey, Suchita; Kumar, Jitender; Awasthi, A M

    2016-03-07

    The magneto-dielectric spectroscopy of La0.95Ca0.05CoO3 covering the crossover of spin states reveals the strong coupling of its spin and dipolar degrees of freedom. The signature of the spin-state transition at 30 K clearly manifests in the magnetization data at a 1 Tesla optimal field. Our Co L3,2-edge X-ray absorption spectrum on the doped specimen is consistent with its suppressed low-to-intermediate spin-state transition temperature at ∼30 K compared to ∼150 K, documented for pure LaCoO3. The dispersive activation step in the dielectric constant with the associated relaxation peak in imaginary permittivity characterize the allied influence of coexistent spin-states on the dielectric character. Dipolar relaxation in the low-spin regime below the transition temperature is partly segmental (Vogel-Fulcher-Tamman (VFT) kinetics) and features magnetic-field tunability, whereas in the low/intermediate-spin disordered state above ∼30 K, it is uncorrelated (Arrhenic kinetics) and almost impervious to the magnetic field H. Kinetics-switchover defines the dipolar-glass transition temperature Tg(H) (=27 K|0T), below which their magneto-thermally-activated cooperative relaxations freeze out by the VFT temperature T0(H) (=15 K|0T). An applied magnetic field facilitates thermal activation in toggling the low spins up into the intermediate states. Consequently, the downsized dipolar-glass segments in the low-spin state and the independent dipoles in the intermediate state exhibit accelerated dynamics. A critical 5 Tesla field collapses the entire relaxation kinetics into a single Arrhenic behaviour, signaling that the dipolar glass is completely devitrified under all higher fields. The magneto-electricity (ME) spanning sizeable thermo-spectral range registers diverse signatures here in kinetic, spectral, and field behaviors, in contrast to the static/perturbative ME observed close to the spin-ordering in typical multiferroics. Intrinsic magneto-dielectricity (50%) along

  1. Multiphysics control of a two-fluid coaxial atomizer supported by electric-charge on the liquid jet

    Science.gov (United States)

    Machicoane, Nathanael; Osuna, Rodrigo; Aliseda, Alberto

    2017-11-01

    We present an experimental setup to investigate multiphysics control strategies on atomization of a laminar fluid stream by a coaxial turbulent jet. Spray control (i.e. driving the droplet size distribution and the spatio-temporal location of the droplets towards a desired objective) has many potential engineering applications, but requires a mechanistic understanding of the processes that control droplet formation and transport (primary and secondary instabilities, turbulent transport, hydrodynamic and electric forces on the droplets, ...). We characterize experimentally the break-up dynamics in a canonical coaxial atomizer, and the spray structure (droplet size, location, and velocity as a function of time) in a series of open loop conditions with harmonic forcing of the gas swirl ratio, liquid injection rate, the electric field strength at the nozzle and along the spray development region. The effect of these actuators are characterized for different gas Reynolds numbers ranging from 104-106. This open-loop characterization of the injector will be used to develop reduced order models for feedback control, as well as to validate assumptions underlying an adjoint-based computational control strategy. This work is part of a large-scale project funded by an ONR MURI to provide fundamental understanding of the mechanisms for feedback control of sprays.

  2. System Dynamic Model for the Accumulation of Renewable Electricity using Power-to-Gas and Power-to-Liquid Concepts

    Directory of Open Access Journals (Sweden)

    Blumberga Andra

    2015-12-01

    Full Text Available When the renewable energy is used, the challenge is match the supply of intermittent energy with the demand for energy therefore the energy storage solutions should be used. This paper is dedicated to hydrogen accumulation from wind sources. The case study investigates the conceptual system that uses intermitted renewable energy resources to produce hydrogen (power-to-gas concept and fuel (power-to-liquid concept. For this specific case study hydrogen is produced from surplus electricity generated by wind power plant trough electrolysis process and fuel is obtained by upgrading biogas to biomethane using hydrogen. System dynamic model is created for this conceptual system. The developed system dynamics model has been used to simulate 2 different scenarios. The results show that in both scenarios the point at which the all electricity needs of Latvia are covered is obtained. Moreover, the methodology of system dynamics used in this paper is white-box model that allows to apply the developed model to other case studies and/or to modify model based on the newest data. The developed model can be used for both scientific research and policy makers to better understand the dynamic relation within the system and the response of system to changes in both internal and external factors.

  3. Numerical Study on Deformation and Interior Flow of a Droplet Suspended in Viscous Liquid under Steady Electric Fields

    Directory of Open Access Journals (Sweden)

    Zhentao Wang

    2014-07-01

    Full Text Available A model based on the volume of fluid (VOF method and leaky dielectric theory is established to predict the deformation and internal flow of the droplet suspended in another vicious fluid under the influence of the electric field. Through coupling with hydrodynamics and electrostatics, the rate of deformation and internal flow of the single droplet are simulated and obtained under the different operating parameters. The calculated results show that the direction of deformation and internal flow depends on the physical properties of fluids. The numerical results are compared with Taylor's theory and experimental results by Torza et al. When the rate of deformation is small, the numerical results are consistent with theory and experimental results, and when the rate is large the numerical results are consistent with experimental results but are different from Taylor's theory. In addition, fluid viscosity hardly affects the deformation rate and mainly dominates the deformation velocity. For high viscosity droplet spends more time to attain the steady state. The conductivity ratio and permittivity ratio of two different liquids affect the direction of deformation. When fluid electric properties change, the charge distribution at the interface is various, which leads to the droplet different deformation shapes.

  4. Leaching of indium from obsolete liquid crystal displays: comparing grinding with electrical disintegration in context of LCA.

    Science.gov (United States)

    Dodbiba, Gjergj; Nagai, Hiroki; Wang, Li Pang; Okaya, Katsunori; Fujita, Toyohisa

    2012-10-01

    In order to develop an effective recycling system for obsolete Liquid Crystal Displays (LCDs), which would enable both the leaching of indium (In) and the recovery of a pure glass fraction for recycling, an effective liberation or size-reduction method would be an important pre-treatment step. Therefore, in this study, two different types of liberation methods: (1) conventional grinding, and (2) electrical disintegration have been tested and evaluated in the context of Life Cycle Assessment (LCA). In other words, the above-mentioned methods were compared in order to find out the one that ensures the highest leaching capacity for indium, as well as the lowest environmental burden. One of the main findings of this study was that the electrical disintegration was the most effective liberation method, since it fully liberated the indium containing-layer, ensuring a leaching capacity of 968.5mg-In/kg-LCD. In turn, the estimate for the environmental burden was approximately five times smaller when compared with the conventional grinding. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Influence of Liquid Petroleum Gas on the Electrical Parameters of the WO3 Thick Film

    Directory of Open Access Journals (Sweden)

    R. S. KHADAYATE

    2007-02-01

    Full Text Available In this work, the WO3 thick films were prepared by standard screen-printing technology. These films were characterized by x-ray diffraction (XRD measurements and scanning electron microscopy (SEM. Influence of LPG on the electrical properties of the prepared WO3 thick film is reported. It was observed that the slope of the Arrhenius curves of the WO3 thick film decreased as the medium changed from pure air to 100 ppm LPG in air. From I-V characteristics, it was observed that the WO3 thick film exhibit highest sensitivity to 50 ppm LPG in air at 400oC.

  6. Global characterization of nematic liquid crystal display Sony LCX038ARA with applied electric field in the modulation amplitude-coupled regime

    Science.gov (United States)

    Cuevas Cely, C. J.; Acevedo Cáceres, C. H.; Torres Moreno, Y.

    2017-06-01

    In this work, we showed experimental and theoretical results of the characterization of a spatial light modulator based in a nematic liquid crystal display Sony model LCX038ARA with electric field excitation. The parameters: effective molecular twist and equivalent retardation are determinated using the retarder-rotor technique in the amplitude-coupled regime.

  7. Real-time tunability of chip-based light source enabled by microfluidic mixing

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Rasmussen, Torben; Balslev, Søren

    2006-01-01

    We demonstrate real-time tunability of a chip-based liquid light source enabled by microfluidic mixing. The mixer and light source are fabricated in SU-8 which is suitable for integration in SU-8-based laboratory-on-a-chip microsystems. The tunability of the light source is achieved by changing...

  8. Electric Sensors for Express-Method Checking of Liquid Quality Level Monitoring

    Directory of Open Access Journals (Sweden)

    Petro STOLYARCHUK

    2010-02-01

    Full Text Available The research covered in the suggested article is meant for ecological monitoring in the broad sense. The express-method of water solution quality level estimation and the technique of fast response to the quality level of industrial, agricultural and domestic wastewaters along with food products are proposed. The novelty of the proposed technique roots in the implementation of suggested methods and means of electric parameter measurement aimed at the quality index controlling of nonelectric qualimetry objects. Relevant research includes the exploration of water-solutions as well as different-level purification of industrial and domestic spillage waters, colloid solutions (cream, milk with the known contaminants, mixtures of superficially active substances and chlorine-containing substances.

  9. Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

    Science.gov (United States)

    Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

    2016-05-01

    Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

  10. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Science.gov (United States)

    Qazi, H. I. A.; Nie, Qiu-Yue; Li, He-Ping; Zhang, Xiao-Fei; Bao, Cheng-Yu

    2015-12-01

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A-X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  11. Coupled electric fields in photorefractive driven liquid crystal hybrid cells - theory and numerical simulation

    Science.gov (United States)

    Moszczyński, P.; Walczak, A.; Marciniak, P.

    2016-12-01

    In cyclic articles previously published we described and analysed self-organized light fibres inside a liquid crystalline (LC) cell contained photosensitive polymer (PP) layer. Such asymmetric LC cell we call a hybrid LC cell. Light fibre arises along a laser beam path directed in plane of an LC cell. It means that a laser beam is parallel to photosensitive layer. We observed the asymmetric LC cell response on an external driving field polarization. Observation has been done for an AC field first. It is the reason we decided to carry out a detailed research for a DC driving field to obtain an LC cell response step by step. The properly prepared LC cell has been built with an isolating layer and garbage ions deletion. We proved by means of a physical model, as well as a numerical simulation that LC asymmetric response strongly depends on junction barriers between PP and LC layers. New parametric model for a junction barrier on PP/LC boundary has been proposed. Such model is very useful because of lack of proper conductivity and charge carriers of band structure data on LC material.

  12. Fast-Response Liquid Crystal Microlens

    Directory of Open Access Journals (Sweden)

    Su Xu

    2014-06-01

    Full Text Available Electrically tunable liquid crystal microlenses have attracted strong research attention due to their advantages of tunable focusing, voltage actuation, low power consumption, simple fabrication, compact structure, and good stability. They are expected to be essential optical devices with widespread applications. However, the slow response time of nematic liquid crystal (LC microlenses has been a significant technical barrier to practical applications and commercialization. LC/polymer composites, consisting of LC and monomer, are an important extension of pure LC systems, which offer more flexibility and much richer functionality than LC alone. Due to the anchoring effect of a polymer network, microlenses, based on LC/polymer composites, have relatively fast response time in comparison with pure nematic LC microlenses. In addition, polymer-stabilized blue phase liquid crystal (PS-BPLC based on Kerr effect is emerging as a promising candidate for new photonics application. The major attractions of PS-BPLC are submillisecond response time and no need for surface alignment layer. In this paper, we review two types of fast-response microlenses based on LC/polymer composites: polymer dispersed/stabilized nematic LC and polymer-stabilized blue phase LC. Their basic operating principles are introduced and recent progress is reviewed by examples from recent literature. Finally, the major challenges and future perspectives are discussed.

  13. Tunable metamaterial dual-band terahertz absorber

    Science.gov (United States)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  14. Electrical charging effects on the sliding friction of a model nano-confined ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Capozza, R.; Vanossi, A. [International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste (Italy); CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); Benassi, A. [CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Tosatti, E. [International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste (Italy); CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); International Centre for Theoretical Physics (ICTP), Strada Costiera 11, 34014 Trieste (Italy)

    2015-10-14

    Recent measurements suggest the possibility to exploit ionic liquids (ILs) as smart lubricants for nano-contacts, tuning their tribological and rheological properties by charging the sliding interfaces. Following our earlier theoretical study of charging effects on nanoscale confinement and squeezout of a model IL, we present here molecular dynamics simulations of the frictional and lubrication properties of that model under charging conditions. First, we describe the case when two equally charged plates slide while being held together to a confinement distance of a few molecular layers. The shear sliding stress is found to rise strongly and discontinuously as the number of IL layers decreases stepwise. However, the shear stress shows, within each given number of layers, only a weak dependence upon the precise value of the normal load, a result in agreement with data extracted from recent experiments. We subsequently describe the case of opposite charging of the sliding plates and follow the shear stress when the charging is slowly and adiabatically reversed in the course of time, under fixed load. Despite the fixed load, the number and structure of the confined IL layers change with changing charge, and that in turn drives strong friction variations. The latter involves first of all charging-induced freezing of the IL film, followed by a discharging-induced melting, both made possible by the nanoscale confinement. Another mechanism for charging-induced frictional changes is a shift of the plane of maximum shear from mid-film to the plate-film interface, and vice versa. While these occurrences and results invariably depend upon the parameters of the model IL and upon its specific interaction with the plates, the present study helps identifying a variety of possible behavior, obtained under very simple assumptions, while connecting it to an underlying equilibrium thermodynamics picture.

  15. Dynamic behaviour of a ferro-electric liquid crystal by means of nuclear magnetic resonance and dielectric spectroscopy

    Science.gov (United States)

    Domenici, Valentina; Marini, Alberto; Menicagli, Rita; Veracini, Carlo Alberto; Bubnov, Aleksej M.; Glogarova, Milada

    2007-05-01

    The field of ferroelectric liquid crystals (FLCs) is one of the most fascinating aspects of the Science of Materials for their interesting electro-optic applications. Among different chemical and physical properties those related to the molecular dynamics are very stimulating due to the relationship between molecular motions and macroscopic response to external fields, such as electric and magnetic ones. In this work, the molecular dynamics of a ferroelectric smectogen, namely the (S)-2-methylbutyl-[4'-(4"-heptyloxyphenyl)-benzoyl-4-oxy-(S)-2-((S)-2')-benzoyl)-propionyl)]-propionate (ZLL 7/*) has been investigated by means of 2H NMR and dielectric relaxation techniques. The first method allows us to get information on the molecular motions in the fast motion regime, in particular the diffusion reorientational motions of the whole molecule, as well as of the internal motions affecting the phenyl and biphenyl fragments. The second technique, which covers the slow motion regime, has been used to detect collective motions and fluctuation modes. This study allows us to have a complete idea of molecular motions in the different smectic phases formed by the ZLL 7/* mesogens, in particular the paraelectric smectic A (SmA), the ferroelectric smectic C* (SmC*), the antiferroelectric smectic C* A (SmC* A) and the re-entrant ferroelectric smectic C* (SmC* r) phases. This last phase has been investigated for the first time in this work, from the point of view of the dynamic behaviour. All results will be discussed in the framework of the molecular dynamics of ferroelectric liquid crystals, reported in the literature so far.

  16. Structural and electrical characteristics of n-InSb/p-GaAs heterojunction prepared by liquid phase epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Farag, A.A.M., E-mail: alaafaragg@edu.asu.edu.eg [Thin Film Laboratory, Physics Department, Faculty of Education, Ain Shams University (Egypt); Terra, F.S.; Ashery, A.; Mansour, A.M. [Solid State Electronics Laboratory, Physics Division, National Research Center, Dokki, Giza (Egypt)

    2014-12-05

    Highlights: • Growth of n-InSb/p-GaAs heterostructure employing LPE technique. • Optimizing several junction parameters of n-InSb/p-GaAs heterostructure parameters. • Study J–V and C–V characteristics n-InSb/p-GaAs heterostructure. - Abstract: Thin films of n-InSb were successfully fabricated on p-GaAs single crystalline substrates by liquid phase epitaxy, LPE. The elemental composition of the prepared films was confirmed by energy dispersive X-ray (EDX) spectroscopy. The morphology and crystal structure of the film were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The electrical characteristics of liquid phase epitaxially grown n-InSb thin films on GaAs single crystal were investigated. The current density–voltage (J–V) characteristics of n-InSb/p-GaAs heterojunction diode in dark condition were measured at different temperatures in the temperature range 300–400 K. The device exhibited a rectifying property. The current in the prepared heterojunction was found to obey the thermionic emission model in the voltage range (V < 0.4 V) while in the voltage range (0.4 < V < 1.5) the current is space charge limited dominated by single trap distribution. The current density–voltage characteristics allow us to evaluate some characteristic parameters such as the series resistance, R{sub s}, shunt resistance, R{sub sh}, ideality factor, n, and the barrier height, Φ{sub b}. The variation of 1/C{sup 2} with voltage shows a straight line at high frequency indicating the formation of barrier between InSb and GaAs and other important parameters were calculated.

  17. Harvesting vibrational energy with liquid-bridged electrodes: thermodynamics in mechanically and electrically driven RC-circuits

    NARCIS (Netherlands)

    Janssen, Mathijs; Werkhoven, Ben; Van Roij, René

    2016-01-01

    We theoretically study a vibrating pair of parallel electrodes bridged by a (deformed) liquid droplet, which is a recently developed microfluidic device to harvest vibrational energy. The device can operate with various liquids, including liquid metals, electrolytes, as well as ionic liquids. We

  18. Self-assembled tunable networks of sticky colloidal particles

    Energy Technology Data Exchange (ETDEWEB)

    Demortiere, Arnaud; Snezhko, Oleksiy Alexey; Sapozhnikov, Maksim; Becker, Nicholas G.; Proslier, Thomas; Aronson, Igor S.

    2017-07-18

    Self-assembled tunable networks of microscopic polymer fibers ranging from wavy colloidal "fur" to highly interconnected networks are created from polymer systems and an applied electric field. The networks emerge via dynamic self-assembly in an alternating (ac) electric field from a non-aqueous suspension of "sticky" polymeric colloidal particles with a controlled degree of polymerization. The resulting architectures are tuned by the frequency and amplitude of the electric field and surface properties of the particles.

  19. Tunable Microfluidic Dye Laser

    DEFF Research Database (Denmark)

    Olsen, Brian Bilenberg; Helbo, Bjarne; Kutter, Jörg Peter

    2003-01-01

    We present a tunable microfluidic dye laser fabricated in SU-8. The tunability is enabled by integrating a microfluidic diffusion mixer with an existing microfluidic dye laser design by Helbo et al. By controlling the relative flows in the mixer between a dye solution and a solvent......, the concentration of dye in the laser cavity can be adjusted, allowing the wavelength to be tuned. Wavelength tuning controlled by the dye concentration was demonstrated with macroscopic dye lasers already in 1971, but this principle only becomes practically applicable by the use of microfluidic mixing...

  20. Optically tunable chirped fiber Bragg grating.

    Science.gov (United States)

    Li, Zhen; Chen, Zhe; Hsiao, V K S; Tang, Jie-Yuan; Zhao, Fuli; Jiang, Shao-Ji

    2012-05-07

    This work presents an optically tunable chirped fiber Bragg grating (CFBG). The CFBG is obtained by a side-polished fiber Bragg grating (SPFBG) whose thickness of the residual cladding layer in the polished area (D(RC)) varies with position along the length of the grating, which is coated with a photoresponsive liquid crystal (LC) overlay. The reflection spectrum of the CFBG is tuned by refractive index (RI) modulation, which comes from the phase transition of the overlaid photoresponsive LC under ultraviolet (UV) light irradiation. The broadening in the reflection spectrum and corresponding shift in the central wavelength are observed with UV light irradiation density of 0.64mW/mm. During the phase transition of the photoresponsive LC, the RI increase of the overlaid LC leads to the change of the CFBG reflection spectrum and the change is reversible and repeatable. The optically tunable CFBGs have potential use in optical DWDM system and an all-fiber telecommunication system.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    Photonic crystal fibers (PCFs) have attracted significant attention during the last years and much research has been devoted to develop fiber designs for various applications, hereunder tunable fiber devices. Recently, thermally and electrically tunable PCF devices based on liquid crystals (LCs......) have been demonstrated. However, optical tuning of the LC PCF has until now not been demonstrated. Here we demonstrate an all-optical modulator, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid...... crystal. We demonstrate a modulation frequency of 2kHz for a moderate pump power of 2-3mW and describe two pump pulse regimes in which there is an order of magnitude difference between the decay times....

  2. Sterilization of liquid foods by pulsed electric fields – an innovative ultra-high temperature process

    Directory of Open Access Journals (Sweden)

    Kai eReineke

    2015-05-01

    Full Text Available The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm-1, skim milk (0.3% fat; 5.3 mS cm-1 and fresh prepared carrot juice (7.73 mS cm-1. The combination of moderate preheating (70-90 °C and an insulated PEF-chamber, combined with a holding tube (65 cm and a heat exchanger for cooling, enabled a rapid heat up to 105-140 °C (measured above the PEF chamber within 92.2-368.9 µs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using Comsol Multiphysics combined with a Matlab routine.A preheating of saline water to 70 °C with a flow rate of 5 l h-1, a frequency of 150 Hz and an energy input of 226.5 kJ kg-1, resulted in a measured outlet temperature of 117 °C and a 4.67 log10 inactivation of Bacillus subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for Geobacillus stearothermophilus spores in saline water. A preheating to 95 °C and an energy input of 144 kJ kg-1 resulted in an outlet temperature of 126 °C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10 was achieved during the thermal treatment.Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring

  3. Crystalline Electric-Field Randomness in the Triangular Lattice Spin-Liquid YbMgGaO_{4}.

    Science.gov (United States)

    Li, Yuesheng; Adroja, Devashibhai; Bewley, Robert I; Voneshen, David; Tsirlin, Alexander A; Gegenwart, Philipp; Zhang, Qingming

    2017-03-10

    We apply moderate-high-energy inelastic neutron scattering (INS) measurements to investigate Yb^{3+} crystalline electric field (CEF) levels in the triangular spin-liquid candidate YbMgGaO_{4}. Three CEF excitations from the ground-state Kramers doublet are centered at the energies ℏω=39, 61, and 97 meV in agreement with the effective spin-1/2 g factors and experimental heat capacity, but reveal sizable broadening. We argue that this broadening originates from the site mixing between Mg^{2+} and Ga^{3+} giving rise to a distribution of Yb-O distances and orientations and, thus, of CEF parameters that account for the peculiar energy profile of the CEF excitations. The CEF randomness gives rise to a distribution of the effective spin-1/2 g factors and explains the unprecedented broadening of low-energy magnetic excitations in the fully polarized ferromagnetic phase of YbMgGaO_{4}, although a distribution of magnetic couplings due to the Mg/Ga disorder may be important as well.

  4. Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena

    Directory of Open Access Journals (Sweden)

    Yuriy Garbovskiy

    2015-11-01

    Full Text Available The presence of ions in liquid crystals is one of the grand challenges that hinder the application of liquid crystals in various devices, which include advanced 3-D and flexible displays, tunable lenses, etc. Not only do they compromise the overall performance of liquid crystal devices, ions are also responsible for slow response, image sticking, and image flickering, as well as many other negative effects. Even highly purified liquid crystal materials can get contaminated during the manufacturing process. Moreover, liquid crystals can degrade over time and generate ions. All of these factors raise the bar for their quality control, and increase the manufacturing cost of liquid crystal products. A decade of dedicated research has paved the way to the solution of the issues mentioned above through merging liquid crystals and nanotechnology. Nano-objects (guests that are embedded in the liquid crystals (hosts can trap ions, which decreases the ion concentration and electrical conductivity, and improves the electro-optical response of the host. In this paper, we (i review recently published works reporting the effects of nanoscale dopants on the electrical properties of liquid crystals; and (ii identify the most promising inorganic and organic nanomaterials suitable to capture ions in liquid crystals.

  5. Tunability enhanced electromagnetic wiggler

    Science.gov (United States)

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  6. MEMS Tunable nanostructured photodetector

    DEFF Research Database (Denmark)

    Learkthanakhachon, Supannee

    This thesis was prepared at the department of Photonics Engineering, the Technical University of Denmark in fulfilment of the requirements for acquiring a Philosophiae doctor (Ph.D.) in Photonics Engineering. The thesis deals with the design and fabrication of tunable resonant-cavity-enhanced pho...

  7. Polarization-coupled tunable resistive behavior in oxide ferroelectric heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gruverman, Alexei [Univ. of Nebraska, Lincoln, NE (United States); Tsymbal, Evgeny Y. [Univ. of Nebraska, Lincoln, NE (United States); Eom, Chang-Beom [Univ. of Wisconsin, Madison, WI (United States)

    2017-05-03

    This research focuses on investigation of the physical mechanism of the electrically and mechanically tunable resistive behavior in oxide ferroelectric heterostructures with engineered interfaces realized via a strong coupling of ferroelectric polarization with tunneling electroresistance and metal-insulator (M-I) transitions. This report describes observation of electrically conductive domain walls in semiconducting ferroelectrics, voltage-free control of resistive switching and demonstration of a new mechanism of electrical control of 2D electron gas (2DEG) at oxide interfaces. The research goals are achieved by creating strong synergy between cutting-edge fabrication of epitaxial single-crystalline complex oxides, nanoscale electrical characterization by scanning probe microscopy and theoretical modeling of the observed phenomena. The concept of the ferroelectric devices with electrically and mechanically tunable nonvolatile resistance represents a new paradigm shift in realization of the next-generation of non-volatile memory devices and low-power logic switches.

  8. Polarization modulation by tunable electromagnetic metamaterial reflector/absorber.

    Science.gov (United States)

    Zhu, Bo; Feng, Yijun; Zhao, Junming; Huang, Ci; Wang, Zhengbin; Jiang, Tian

    2010-10-25

    We propose a polarization modulation scheme of electromagnetic (EM) waves through reflection of a tunable metamaterial reflector/absorber. By constructing the metamaterial with resonant unit cells coupled by diodes, we demonstrate that the EM reflections for orthogonal polarized incident waves can be tuned independently by adjusting the bias voltages on the corresponding diodes. Owing to this feature, the reflected EM waves can be electrically controlled to a linear polarization with continuously tunable azimuth angle from 0° to 90° at the resonant frequency, or an elliptical polarization with tunable azimuth angle of the major axis when off the resonant frequency. The proposed property has been verified through both numerical simulations and experimental measurements at microwave band, which enables us to electrically modulate the polarization state of EM waves flexibly.

  9. Phosphonium–based ionic liquid as dispersing agent for MWCNT in melt-mixing polystyrene blends: Rheology, electrical properties and EMI shielding effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Soares da Silva, Jéssica P. [Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas, 21941-598, Rio de Janeiro (Brazil); Soares, Bluma G., E-mail: bluma@metalmat.ufrj.br [Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas, 21941-598, Rio de Janeiro (Brazil); Universidade Federal do Rio de Janeiro, Programa de Engenharia Metalurgica e de Materiais - COPPE, Centro de Tecnologia, 21941-972, Rio de Janeiro (Brazil); Livi, Sebastien [Université de Lyon, F-69003, Lyon (France); INSA Lyon, F-69621, Villeurbanne (France); CNRS, UMR 5223, Ingénierie des Matériaux Polymères (France); Barra, Guilherme M.O. [Universidade Federal de Santa Catarina, Departamento de Engenharia Mecânica, Florianópolis, SC (Brazil)

    2017-03-01

    Conducting nanocomposites composed with polystyrene (PS) and multi-walled carbon nanotubes (MWCNT) were prepared by melt mixing procedure assisted by trihexyl-(tetradecyl)-phosphonium combined with bis(trifluoromethylsulfonyl) amide counteranion (TFSI) as the ionic liquid (IL). The non-covalent functionalization of MWCNT with the IL was confirmed by Raman spectroscopy and thermogravimetric analysis. The functionalized MWCNT provided better dispersion of the MWCNT within PS matrix, as indicated by transmission electron microscopy (TEM), and also an electrical conductivity as high as 10{sup −1} S/m with 0.66 m% of MWCNT combined with 3.34 m% of IL. This value is around four orders of magnitude higher when compared to nanocomposites with similar amount of untreated MWCNT. From rheological studies, it was observed that the transition between liquid-like to solid-like behavior occurred at lower frequencies for the systems containing functionalized MWCNT. Moreover, an improvement of around 170% in the electromagnetic interference shielding effectiveness (EMI SE) in the X-band frequency range was observed for the nanocomposites containing 1% of MWCNT non-covalently functionalized with the IL, that is, 1% of MWCNT and 5% of IL. - Highlights: • MWCNT well dispersed in PS matrix, in the presence of ionic liquid. • Outstanding electric conductivity of PS/MWCNT nanocomposite. • Improved EMI shielding effectiveness by addition of ionic liquid in PS/MWCNT nanocomposite.

  10. Reversible Control of Anisotropic Electrical Conductivity using Colloidal Microfluidic Networks

    National Research Council Canada - National Science Library

    Beskok, Ali; Bevan, Michael; Lagoudas, Dimitris; Ounaies, Zoubeida; Bahukudumbi, Pradipkumar; Everett, William

    2007-01-01

    This research addresses the tunable assembly of reversible colloidal structures within microfluidic networks to engineer multifunctional materials that exhibit a wide range of electrical properties...

  11. Electrically excited liquid water

    NARCIS (Netherlands)

    Wexler, A.D.

    2016-01-01

    Water is essential to a healthy and secure world. Developing new technologies which can take full advantage of the unique attributes of water is important for meeting the ever increasing global demand while reducing the production footprint. Water exhibits unexpected departures in more than 70

  12. Liquid Phase Separation and the Aging Effect on Mechanical and Electrical Properties of Laser Rapidly Solidified Cu100−xCrx Alloys

    Directory of Open Access Journals (Sweden)

    Song-Hua Si

    2015-11-01

    Full Text Available Duplex structure Cu-Cr alloys are widely used as contact materials. They are generally designed by increasing the Cr content for the hardness improvement, which, however, leads to the unfavorable rapid increase of the electrical resistivity. The solidification behavior of Cu100−xCrx (x = 4.2, 25 and 50 in wt.% alloys prepared by laser rapid solidification is studied here, and their hardness and electrical conductivity after aging are measured. The results show that the Cu-4.2%Cr alloy has the most desirable combination of hardness and conductive properties after aging in comparison with Cu-25%Cr and Cu-50%Cr alloys. Very importantly, a 50% improvement in hardness is achieved with a simultaneous 70% reduction in electrical resistivity. The reason is mainly attributed to the liquid phase separation occurring in the Cu-4.2%Cr alloy, which introduces a large a

  13. Tunable laser optics

    CERN Document Server

    Duarte, FJ

    2015-01-01

    This Second Edition of a bestselling book describes the optics and optical principles needed to build lasers. It also highlights the optics instrumentation necessary to characterize laser emissions and focuses on laser-based optical instrumentation. The book emphasizes practical and utilitarian aspects of relevant optics including the essential theory. This revised, expanded, and improved edition contains new material on tunable lasers and discusses relevant topics in quantum optics.

  14. Tunable high pressure lasers

    Science.gov (United States)

    Hess, R. V.

    1976-01-01

    Atmospheric transmission of high energy CO2 lasers is considerably improved by high pressure operation which, due to pressure broadening, permits tuning the laser lines off atmospheric absorption lines. Pronounced improvement is shown for horizontal transmission at altitudes above several kilometers and for vertical transmission through the entire atmosphere. Applications of tunable high pressure CO2 lasers to energy transmission and to remote sensing are discussed along with initial efforts in tuning high pressure CO2 lasers.

  15. Tunable and Memory Metamaterials

    Science.gov (United States)

    2015-12-02

    direction of the proposed work was to implement graphene -based metamaterials . A complimentary direction of research was focused on the development and...tunability of the electromagnetic response. The PI has investigated various schemes for implementation of graphene -based metamaterials . One outcome...of this work is that plasmonic-based approaches were established to be most beneficial for realization of graphene -based metamaterials [Nature

  16. Tunable interacting composite fermion phases in a half-filled bilayer-graphene Landau level

    Science.gov (United States)

    Zibrov, A. A.; Kometter, C.; Zhou, H.; Spanton, E. M.; Taniguchi, T.; Watanabe, K.; Zaletel, M. P.; Young, A. F.

    2017-09-01

    Non-Abelian anyons are a type of quasiparticle with the potential to encode quantum information in topological qubits protected from decoherence. Experimental systems that are predicted to harbour non-Abelian anyons include p-wave superfluids, superconducting systems with strong spin–orbit coupling, and paired states of interacting composite fermions that emerge at even denominators in the fractional quantum Hall (FQH) regime. Although even-denominator FQH states have been observed in several two-dimensional systems, small energy gaps and limited tunability have stymied definitive experimental probes of their non-Abelian nature. Here we report the observation of robust even-denominator FQH phases at half-integer Landau-level filling in van der Waals heterostructures consisting of dual-gated, hexagonal-boron-nitride-encapsulated bilayer graphene. The measured energy gap is three times larger than observed previously. We compare these FQH phases with numerical and theoretical models while simultaneously controlling the carrier density, layer polarization and magnetic field, and find evidence for the paired Pfaffian phase that is predicted to host non-Abelian anyons. Electric-field-controlled level crossings between states with different Landau-level indices reveal a cascade of FQH phase transitions, including a continuous phase transition between the even-denominator FQH state and a compressible composite fermion liquid. Our results establish graphene as a pristine and tunable experimental platform for studying the interplay between topology and quantum criticality, and for detecting non-Abelian qubits.

  17. Lightweight Tunable Infrared Filter Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Michigan Aerospace Corporation has developed spaceflight qualified compact tunable Fabry-Perot interferometers for a number of applications, from ranging direct...

  18. Magnetic nanoparticles for tunable microwave metamaterials

    KAUST Repository

    Noginova, Natalia

    2012-09-24

    Commonly, metamaterials are electrically engineered systems with optimized spatial arrangement of subwavelength sized metal and dielectric components. We explore alternative methods based on use of magnetic inclusions, such as magnetic nanoparticles, which can allow permeability of a composite to be tuned from negative to positive at the range of magnetic resonance. To better understand effects of particle size and magnetization dynamics, we performed electron magnetic resonance study on several varieties of magnetic nanoparticles and determined potential of nanoparticle use as building blocks for tunable microwave metamaterials. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  19. Tunable Holstein model with cold polar molecules

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Felipe; Krems, Roman V. [Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1 (Canada)

    2011-11-15

    We show that an ensemble of polar molecules trapped in an optical lattice can be considered as a controllable open quantum system. The coupling between collective rotational excitations and the motion of the molecules in the lattice potential can be controlled by varying the strength and orientation of an external dc electric field as well as the intensity of the trapping laser. The system can be described by a generalized Holstein Hamiltonian with tunable parameters and can be used as a quantum simulator of excitation energy transfer and polaron phenomena. We show that the character of excitation energy transfer can be modified by tuning experimental parameters.

  20. Feasibility studies on selected bioenergy concepts producing electricity, heat, and liquid fuel. IEA Bioenergy, Techno-economic analysis activity

    Energy Technology Data Exchange (ETDEWEB)

    Solantausta, Y.; Koljonen, T. [VTT Energy, Espoo (Finland); Podesser, E. [Joanneum Research (Austria); Beckman, D. [Zeton Inc. (Canada); Overend, R. [National Renewable Energy Lab. (United States)

    1999-07-01

    The IEA Bioenergy Techno-Economic Analysis Activity reported here, had the following objectives: To assist companies working with technologies and products related to bioenergy applications in their efforts to demonstrate these; To promote bioenergy technologies, processes and applications; To build and maintain a network for R and D organisations and industry. The objectives were pursued 1995 - 1997 through carrying out site-specific prefeasibility studies in participating countries. Both electricity and liquid fuel applications were studied, utilising gasification, pyrolysis, and combustion technologies. Studies were carried out in collaboration with companies developing new products or services from participating countries (Austria, Canada, Finland, and the United States of America) in the bioenergy field. Cases are: Austria: Power production at a district heating station, Stirling-engine driven by unclean boiler flue gases, 50 kWe; Canada - Bio-oil production for a boiler power plant, Fast pyrolysis of sawmill wastes and bark, 11 MWe; Finland: Co-generation of power and heat at a pulp and paper mill, Pressurised integrated gasification combined-cycle (IGCC) using bark and wood, 34 MWe; Sweden: Bio-oil production for heating fuel, Fast pyrolysis of forest residues, 20 000 t/a; USA - Case 1: Co-firing in a coal boiler, Combustion of plantation willow, 15 MWe; USA - Case 2: Condensing power production, Pressurised IGCC using alfalfa stems, 75 MWe All of the cases studied are at different stages of development. Results from these case studies are reported together with technical uncertainties and future development needs, which are required for all the systems. In general, the results showed that for most of the cases studied economic conditions are possible, through existing subsidies or tax incentives, for feasible industrial operation. Specially designed Stirling engines have a short amortisation time integrated to biomass district heating plants in Austria

  1. A "counter-charge layer in generalized solvents" framework for electrical double layers in neat and hybrid ionic liquid electrolytes.

    Science.gov (United States)

    Feng, Guang; Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent; Qiao, Rui

    2011-08-28

    Room-temperature ionic liquids (RTILs) have received significant attention as electrolytes due to a number of attractive properties such as their wide electrochemical windows. Since electrical double layers (EDLs) are the cornerstone for the applications of RTILs in electrochemical systems such as supercapacitors, it is important to develop an understanding of the structure-capacitance relationships for the EDLs of these systems. Here we present a theoretical framework termed "counter-charge layer in generalized solvents" (CGS) for describing the structure and capacitance of the EDLs in neat RTILs and in RTILs mixed with different mass fractions of organic solvents. Within this framework, an EDL is made up of a counter-charge layer exactly balancing the electrode charge, and of polarized generalized solvents (in the form of layers of ion pairs, each of which has a zero net charge but has a dipole moment--the ion pairs thus can be considered as a generalized solvent) consisting of all RTILs inside the system except the counter-ions in the counter-charge layer, together with solvent molecules if present. Several key features of the EDLs that originate from the strong ion-ion correlation in RTILs, e.g., overscreening of electrode charge and alternating layering of counter-ions and co-ions, are explicitly incorporated into this framework. We show that the dielectric screening in EDLs is governed predominantly by the polarization of generalized solvents (or ion pairs) in the EDL, and the capacitance of an EDL can be related to its microstructure with few a priori assumptions or simplifications. We use this framework to understand two interesting phenomena observed in molecular dynamics simulations of EDLs in a neat IL of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF(4)]) and in a mixture of [BMIM][BF(4)] and acetonitrile (ACN): (1) the capacitance of the EDLs in the [BMIM][BF(4)]/ACN mixture increases only slightly when the mass fraction of ACN in the mixture

  2. Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air

    OpenAIRE

    Yongjun Men; Martina Ambrogi; Baohang Han; Jiayin Yuan

    2016-01-01

    Ionic liquids and poly(ionic liquid)s have been successfully converted into nitrogen-doped porous carbons with tunable surface area up to 1200 m2/g at high temperatures in air. Compared to conventional carbonization process conducted under inert gas to produce nitrogen-doped carbons, the new production method was completed in a rather shorter time without noble gas protection.

  3. Application of numerical modelling to scaling-up of electrically induced extraction from an organic mixture using an ionic liquid

    Directory of Open Access Journals (Sweden)

    Kamiński Kamil

    2016-03-01

    Full Text Available Liquid-liquid extraction provides an environmentally friendly process as an alternative to azeotropic distillation, pervaporation and reverse osmosis because these techniques require the use of large amounts of energy, may involve volatile organic compounds, and operation at high pressure.

  4. Intramolecular coupling as a mechanism for a liquid-liquid phase transition

    OpenAIRE

    Franzese, Giancarlo; Marqués, Manuel I.; Stanley, H. Eugene

    2003-01-01

    We study a model for water with a tunable intramolecular interaction Js, using mean-field theory and off-lattice Monte Carlo simulations. For all Js>~0, the model displays a temperature of maximum density. For a finite intramolecular interaction Js>0, our calculations support the presence of a liquid-liquid phase transition with a possible liquid-liquid critical point for water, likely preempted by inevitable freezing. For J=0, the liquid-liquid critical point disappears at T=0.

  5. Tunable Nitride Josephson Junctions.

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    We have developed an ambient temperature, SiO2/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the TaxN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlOx barriers for low - power, high - performance computing.

  6. Integrated tunable CMOS laser.

    Science.gov (United States)

    Creazzo, Timothy; Marchena, Elton; Krasulick, Stephen B; Yu, Paul K L; Van Orden, Derek; Spann, John Y; Blivin, Christopher C; He, Lina; Cai, Hong; Dallesasse, John M; Stone, Robert J; Mizrahi, Amit

    2013-11-18

    An integrated tunable CMOS laser for silicon photonics, operating at the C-band, and fabricated in a commercial CMOS foundry is presented. The III-V gain medium section is embedded in the silicon chip, and is hermetically sealed. The gain section is metal bonded to the silicon substrate creating low thermal resistance into the substrate and avoiding lattice mismatch problems. Optical characterization shows high performance in terms of side mode suppression ratio, relative intensity noise, and linewidth that is narrow enough for coherent communications.

  7. Tunable multiwalled nanotube resonator

    Science.gov (United States)

    Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C

    2013-11-05

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  8. Tunable resistance coatings

    Science.gov (United States)

    Elam, Jeffrey W.; Mane, Anil U.

    2015-08-11

    A method and article of manufacture of intermixed tunable resistance composite materials containing at least one of W:Al.sub.2O.sub.3, Mo:Al.sub.2O.sub.3 or M:Al.sub.2O.sub.3 where M is a conducting compound containing either W or Mo. A conducting material and an insulating material are deposited by such methods as ALD or CVD to construct composites with intermixed materials which do not have structure or properties like their bulk counterparts.

  9. Tunable nonlinear graphene metasurfaces

    Science.gov (United States)

    Smirnova, Daria A.; Miroshnichenko, Andrey E.; Kivshar, Yuri S.; Khanikaev, Alexander B.

    2015-10-01

    We introduce an important approach for enhancing the nonlinear response of graphene through its resonant coupling to a plasmonic metasurface via cascaded Fano resonances. Such a hybrid metasurface supports two types of subradiant resonant modes, i.e., asymmetric modes of structured metamaterial elements ("metamolecules") and graphene plasmons exhibiting strong mutual coupling and avoided dispersion crossing. We demonstrate that the tunability of graphene plasmons facilitates the strong interaction between the subradiant modes, modifying the spectral position and lifetime of the Fano resonances. We reveal that a strong resonant interaction, combined with the subwavelength localization of plasmons, leads to an enhanced nonlinear response and high efficiency of the second-harmonic generation.

  10. Harnessing Poly(ionic liquid)s for Sensing Applications

    OpenAIRE

    Guterman, Ryan; Ambrogi, Martina; Yuan, Jiayin

    2016-01-01

    The interest in poly(ionic liquids) for sensing applications are derived from their strong interactions to a variety of analytes. By combining the desirable mechanical properties of polymers with the physical and chemical properties of ILs, new materials can be created. The tunable nature of both ionic liquids and polymers allows for incredible diversity, which is exemplified in their broad applicability. In this article we examine the new field of poly(ionic liquid) sensors by providing a de...

  11. Electrically switchable optical vortex generated by a computer-generated hologram recorded in polymer-dispersed liquid crystals.

    Science.gov (United States)

    Liu, Y J; Sun, X W; Wang, Q; Luo, D

    2007-12-10

    A computer-generated hologram designed to generate an optical vortex was recorded in a cell filled with polymer-dispersed liquid crystal material under a collimated Ar+ laser beam operating at 514.5 nm. Owing to the photopolymerization-induced phase separation between the polymer and the liquid crystal, an index modulation was formed between the polymer-rich and liquid crystal-rich regions. A good optical vortex beam with high fidelity was reconstructed using a collimated He-Ne laser beam. The diffraction efficiency is estimated to be about 13%-17%. With a suitable voltage applied, the reconstructed optical vortex beam can be switched owing to the index change between the polymer and the liquid crystal.

  12. Effects of the vertically switching electric field on the photoelectric properties of polymer-stabilized blue-phase liquid crystal cells using the director model.

    Science.gov (United States)

    Chi, Cheng-Yu; Qiu, Shi-Hao; Lin, Guan-Jhong; Chen, Tien-Jung; Yang, Yin-Jay; Wu, Jin-Jei

    2017-03-20

    This study uses the director model to analyze the optoelectronic properties of polymer-stabilized blue-phase liquid crystal (PS-BPLC). The director model revealed a linear relationship of refractive index change and the cosine squared of the angle between the LCs and the direction of the electric field. Moreover, we employed simulations based on the Kerr effect and compared the results with those of the director model. The simulation results also show high consistency with real circumstances. Consequently, it can be of great help to design BPLC displays that can be applied to adopting better strategies for developing next-generation LCD devices.

  13. A lipophilic ionic liquid based on formamidinium cations and TFSI: the electric response and the effect of CO2 on the conductivity mechanism.

    Science.gov (United States)

    Bertasi, Federico; Giffin, Guinevere A; Vezzù, Keti; Pace, Giuseppe; Abu-Lebdeh, Yaser; Armand, Michel; Di Noto, Vito

    2017-10-04

    This work describes the preparation of the new lipophilic ionic liquid tetraoctyl-formamidinium bis(trifluoromethanesulfonyl) imide (TOFATFSI), which is miscible with lower alkanes. In particular, this work focuses on the electric behaviour of TOFATFSI in the particularly challenging highly apolar environment of supercritical CO2. The conductivity and relaxation phenomena are revealed through the analysis of the broadband electric spectra with a particular emphasis on the effect of temperature and CO2 uptake on the IL conductivity. It is found that temperature boosts the conductivity via an increase in the charge carrier mobility. Also, CO2 absorption affects both the conductivity and the permittivity of the material due to the presence of CO2-IL interactions that modulate the nanostructure and the size of the TOFATFSI aggregates, which increases both the mobility and the density of the charge carriers.

  14. From bulk self-assembly to electrical diffuse layer in a continuum approach for ionic liquids: The impact of anion and cation size asymmetry

    Science.gov (United States)

    Bier, Sariel; Gavish, Nir; Uecker, Hannes; Yochelis, Arik

    2017-06-01

    Ionic liquids are solvent-free electrolytes, some of which possess an intriguing self-assembly at finite length scale due to Coulombic interactions. Using a continuum framework (based on Onsager's relations), it is shown that bulk nanostructures arise via linear (supercritical) and nonlinear (subcritical) bifurcations (morphological phase transitions), which also directly affect the electrical double layer structure. A Ginzburg-Landau amplitude equation is derived and the bifurcation type is related to model parameters, such as temperature, potential, and interactions. Specifically, the nonlinear bifurcation occurs for geometrically dissimilar ions and, surprisingly, is induced by perturbations on the order of thermal fluctuations. Finally, qualitative insights and comparisons to the experimentally decaying charge layers within the electrical double layer are discussed.

  15. Electrokinetic actuation of liquid metal for reconfigurable radio frequency devices

    Science.gov (United States)

    Gough, Ryan C.

    oxide layer. Several proof-of-concept devices are designed and tested to demonstrate the effectiveness of these electrical actuation techniques. A pair of tunable slot antennas are presented that achieve frequency reconfigurability through different implementations of liquid metal tuning elements - the first uses liquid metal as a dynamic short-circuit boundary condition for the magnetic current within the resonant aperture, and the second as a variable-length transmission stub that adds and removes reactance from the antenna. The two antennas are tunable across effective bandwidths of 19% and 15%, respectively. In addition, a tunable bandpass filter is demonstrated in which a central liquid-metal resonant element is 'stretched' to lower the passband of the filter by 10% without impacting the insertion loss. Finally, it is demonstrated how liquid metal can be formed into arbitrary shapes at high speeds (approximately 2.5 cm/s) without the need for an external power supply.

  16. Tunable Topological Phononic Crystals

    KAUST Repository

    Chen, Ze-Guo

    2016-05-27

    Topological insulators first observed in electronic systems have inspired many analogues in photonic and phononic crystals in which remarkable one-way propagation edge states are supported by topologically nontrivial band gaps. Such band gaps can be achieved by breaking the time-reversal symmetry to lift the degeneracy associated with Dirac cones at the corners of the Brillouin zone. Here, we report on our construction of a phononic crystal exhibiting a Dirac-like cone in the Brillouin zone center. We demonstrate that simultaneously breaking the time-reversal symmetry and altering the geometric size of the unit cell result in a topological transition that we verify by the Chern number calculation and edge-mode analysis. We develop a complete model based on the tight binding to uncover the physical mechanisms of the topological transition. Both the model and numerical simulations show that the topology of the band gap is tunable by varying both the velocity field and the geometric size; such tunability may dramatically enrich the design and use of acoustic topological insulators.

  17. Electrothermally Tunable Arch Resonator

    KAUST Repository

    Hajjaj, Amal Z.

    2017-03-18

    This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of electrothermally actuated microelectromechanical arch beams. The beams are made of silicon and are intentionally fabricated with some curvature as in-plane shallow arches. An electrothermal voltage is applied between the anchors of the beam generating a current that controls the axial stress caused by thermal expansion. When the electrothermal voltage increases, the compressive stress increases inside the arch beam. This leads to an increase in its curvature, thereby increasing its resonance frequencies. We show here that the first resonance frequency can increase monotonically up to twice its initial value. We show also that after some electrothermal voltage load, the third resonance frequency starts to become more sensitive to the axial thermal stress, while the first resonance frequency becomes less sensitive. These results can be used as guidelines to utilize arches as wide-range tunable resonators. Analytical results based on the nonlinear Euler Bernoulli beam theory are generated and compared with the experimental data and the results of a multi-physics finite-element model. A good agreement is found among all the results. [2016-0291

  18. Color-tunable light emitting diodes based on quantum dot suspension.

    Science.gov (United States)

    Luo, Zhenyue; Chen, Haiwei; Liu, Yifan; Xu, Su; Wu, Shin-Tson

    2015-04-01

    We propose a color-tunable light emitting diode (LED) consisting of a blue LED as the light source and quantum dot (QD) suspension as the color-conversion medium. The LED color temperature can be controlled by varying the liquid volume of each QD suspension with different photoluminescence colors. We simulate and optimize the light efficiency and color quality of the color-tunable LED and also fabricated a prototype to prove concept. The proposed color-tunable LED exhibits several advantages such as excellent color-rendering property, simple structure and driving mechanism, as well as high energy efficiency. Its potential applications include circadian rhythm regulation and healthy lighting.

  19. Tunable supercontinuum light vector vortex beam generator using a q-plate.

    Science.gov (United States)

    Rumala, Yisa S; Milione, Giovanni; Nguyen, Thien An; Pratavieira, Sebastião; Hossain, Zabir; Nolan, Daniel; Slussarenko, Sergei; Karimi, Ebrahim; Marrucci, Lorenzo; Alfano, Robert R

    2013-12-01

    Spatially coherent multicolored optical vector vortex beams were created using a tunable liquid crystal q-plate and a supercontinuum light source. The feasibility of the q-plate as a tunable spectral filter (switch) was demonstrated, and the polarization topology of the resulting vector vortex beam was mapped. Potential applications include multiplexing for broadband high-speed optical communication, ultradense data networking, and super-resolution microscopy.

  20. Fabrication and electrical characterization of homo- and hetero-structure Si/SiGe nanowire Tunnel Field Effect Transistor grown by vapor-liquid-solid mechanism

    Science.gov (United States)

    Brouzet, V.; Salem, B.; Periwal, P.; Alcotte, R.; Chouchane, F.; Bassani, F.; Baron, T.; Ghibaudo, G.

    2016-04-01

    We demonstrate the fabrication and electrical characterization of Ω -gate Tunnel Field Effect Transistors (TFET) based on p-Si/i-Si/n+Si0.7Ge0.3 heterostructure nanowires grown by Chemical Vapor Deposition (CVD) using the vapor-liquid-solid (VLS) mechanism. The electrical performances of the p-Si/i-Si/n+Si0.7Ge0.3 heterostructure TFET device are presented and compared to Si and Si0.7Ge0.3 homostructure nanowire TFETs. We observe an improvement of the electrical performances of TFET with p-Si/i-Si/n+Si0.7Ge0.3 heterostructure nanowire (HT NW). The optimized devices present an Ion current of about 245 nA at VDS = -0.5 V and VGS = -3 V with a subthreshold swing around 135 mV/dec. Finally, we show that the electrical results are in good agreement with numerical simulation using Kane's Band-to-Band Tunneling model.

  1. Giant tunability of the two-dimensional electron gas at the interface of γ-Al2O3/SrTiO3

    DEFF Research Database (Denmark)

    Niu, Wei; Zhang, Yu; Gan, Yulin

    2017-01-01

    Two-dimensional electron gases (2DEGs) formed at the interface between two oxide insulators provide a rich platform for the next generation of electronic devices. However, their high carrier density makes it rather challenging to control the interface properties under a low electric field through...... a dielectric solid insulator, i.e. in the configuration of conventional field-effect transistors. To surpass this long-standing limit, we used ionic liquids as the dielectric layer for electrostatic gating of oxide interfaces in an electric double layer transistor (EDLT) configuration. Herein, we reported...... giant tunability of the physical properties of 2DEGs at the spinel/perovskite interface of γ-Al2O3/SrTiO3 (GAO/STO). By modulating the carrier density thus the band filling with ionic-liquid gating, the system experiences a Lifshitz transition at a critical carrier density of 3.0×1013 cm-2, where...

  2. Alternative generation of well-aligned uniform lying helix texture in a cholesteric liquid crystal cell

    Science.gov (United States)

    Yu, Chia-Hua; Wu, Po-Chang; Lee, Wei

    2017-10-01

    This work demonstrates a simple approach for obtaining a well-aligned uniform lying helix (ULH) texture and a tri-bistable feature at ambient temperature in a typical 90°-twisted cell filled with a short-pitch cholesteric liquid crystal. This ULH texture is obtained at room temperature from initially field-induced helix-free homeotropic state by gradually decreasing the applied voltage. Depending on the way and rate of reducing the voltage, three stable states (i.e., Grandjean planar, focal conic, and ULH) are generated and switching between any two of them is realized. Moreover, the electrical operation of the cell in the ULH state enables the tunability in phase retardation via the deformation of the ULH. The observations made in this work may be useful for applications such as tunable phase modulators and energy-efficient photonic devices.

  3. Tunable Transmission Line With Nanopatterned Thin Films for Smart RF Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, B. M. Farid; Divan, Ralu; Stan, Liliana; Rosenmann, Daniel; Ocola, Leonidas E.; Wang, Guoan

    2014-11-01

    A concept of tunable transmission line (TL) enabled with nanopatterned ferromagnetic permalloy (Py) and ferroelectric lead zirconium titanate (PZT) thin films is presented. The permittivity (εr) of PZT is electrical tunable with dc voltage, and the permeability (μr) of Py is electrical tunable with dc current, thus simultaneous electric tunable capacitance and inductance capability are provided for the proposed TL. The proposed TL has been fabricated and compared with a regular line without nanofilm patterns. Py is patterned with the dimensions of 10 μm × 150 nm and thickness of 100 nm for high built-in anisotropy field. The ferromagnetic resonant frequency is measured to be 6.3 GHz. Compared with the regular TL, the implemented TL has only generated 0.05 dB additional insertion loss at 4 GHz. The electrical tunability of both the capacitance and the inductance has been demonstrated for the first time. By applying the varied dc current (0–150 mA) and the dc voltage (0–20 V), measured results have shown that the proposed line can provide 90° phase shift from 3.75 to 4 GHz with the fixed characteristic impedance. The continuous tuning of the characteristics impedance from 59 to 61 under suitable bias conditions shows its promise as an impedance matching network. Tunable range of both the phase shifter and the impedance matching network can be further increased with thicker and multilayer films.

  4. Membrane-based aberration-corrected tunable micro-lenses

    Science.gov (United States)

    Waibel, Philipp; Ermantraut, Eugen; Mader, Daniel; Zappe, Hans; Seifert, Andreas

    2010-05-01

    We present measurements and simulations of membrane-based micro-lens stacks, tunable in focal length in the range of 10mm to 50mm without chromatic aberration. The pressure-actuated, liquid-filled, membrane-based micro-lenses are fabricated by an all-silicone molding approach and consist of three chambers separated by two highly flexible silicone-membranes. Based on the idea of the classical achromatic Fraunhofer doublet, two different liquids with suitable optical properties are used. Pressure-dependent surface topologies are measured by profilometry for determining the correlation between refraction and applied pressure. The profiles are fit to polynomials; the coefficients of the polynomials are pressure-dependent and fit to empirically determined functions which are then used as an input for optical ray-tracing. Using this approach, the focal length is tunable while compensating for chromatic aberration by suitably applied pressures.

  5. Electrical breakdown mechanism of cryogenic liquid coolants in the presence of thermal bubbles. Goku teion reibai ekitai no netsu kiho hakai kiko

    Energy Technology Data Exchange (ETDEWEB)

    Hara, M.; Suehiro, J.; Nakamura, I.; Saita, K. (Kyushu Univ., Fukuoka (Japan))

    1991-04-20

    Investigation was made on a breakdown mechanism of a coolant under the simulated condition of a superconducting magnet coil at quenching. The breakdown mechanism was classified in the following 3 points. (1) For an abrupt pulse voltage with micro-second of rising length, the thermal bubbles do not deform, but a series complex insulating system of the gas phase and the liquid phase in the bubble is caused. (2) In the case of a slow rising electric field having a milli-second order rising length, breakdown is caused accompanying the deformation of floating bubbles in the liquid. (3) In the case of slow rising electric field having at least several tens milli-second rising length, bubbles grow from a hot spot and the breakdown is caused in the gas phase after the gap is suspended. The breakdown voltage at this time is near to the DC breakdown voltage of the saturated gas. The characteristics is directly connected to the deformation of heat bubbles when the voltage raising rate is changed in wide range. 19 refs., 11 figs.

  6. Mid-infrared tunable metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A.; Passmore, Brandon Scott

    2017-07-11

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  7. Mid-infrared tunable metamaterials

    Science.gov (United States)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A; Passmore, Brandon Scott; Jun, Young Chul

    2015-04-28

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  8. Tunable grating with active feedback

    Science.gov (United States)

    Rosset, Samuel; O'Brien, Benjamin M.; Gisby, Todd; Xu, Daniel; Shea, Herbert R.; Anderson, Iain A.

    2013-04-01

    We report on the use of capacitive self-sensing to operate a DEA-based tunable grating in closed-loop mode. Due to their large strain capabilities, DEAs are key candidates for tunable optics applications. However, the viscoelasticity of elastomers is detrimental for applications that require long-term stability, such as tunable gratings and lenses. We show that capacitive sensing of the electrode strain can be used to suppress the strain drift and increase the response speed of silicone-based actuators. On the other hand, VHB actuators exhibit a time-dependent permittivity, which causes a drift between the device capacitance and its strain.

  9. Voltage-Impulse-Induced Nonvolatile Control of Inductance in Tunable Magnetoelectric Inductors

    Science.gov (United States)

    Peng, Bin; Zhang, Chenxi; Yan, Yuan; Liu, Ming

    2017-04-01

    In this work, nonvolatile magnetoelectric tunable inductors are developed based on Metglas/(011) Pb (Mg1 /3Nb2 /3)O3-PbTiO3 multiferroic composites. They exhibit a large nonvolatile tunability up to 250% at 10 kHz and 120% at 1 MHz, in which the voltage control of inductance is achieved through strain-mediated magnetoelastic anisotropy. Such high nonvolatile tunability is attributed to a dramatic change of the in-plane lattice strain arising from non-180° ferroelastic domain switching in Pb (Mg1 /3Nb2 /3)O3-PbTiO3 . Electric field dependent inductance is then calculated from the strain-induced effective magnetic field and effective permeability change, and it is consistent with our experimental results. Engineering of ferroelastic domain states in multiferroic composites provides a pathway to realize nonvolatile electrically tunable inductors for lightweight, compact, power-efficient integrated power electronics, rf devices, and systems.

  10. Holographic Polymer-Dispersed Liquid Crystals: Materials, Formation, and Applications

    Directory of Open Access Journals (Sweden)

    Y. J. Liu

    2008-01-01

    Full Text Available By combining polymer-dispersed liquid crystal (PDLC and holography, holographic PDLC (H-PDLC has emerged as a new composite material for switchable or tunable optical devices. Generally, H-PDLC structures are created in a liquid crystal cell filled with polymer-dispersed liquid crystal materials by recording the interference pattern generated by two or more coherent laser beams which is a fast and single-step fabrication. With a relatively ideal phase separation between liquid crystals and polymers, periodic refractive index profile is formed in the cell and thus light can be diffracted. Under a suitable electric field, the light diffraction behavior disappears due to the index matching between liquid crystals and polymers. H-PDLCs show a fast switching time due to the small size of the liquid crystal droplets. So far, H-PDLCs have been applied in many promising applications in photonics, such as flat panel displays, switchable gratings, switchable lasers, switchable microlenses, and switchable photonic crystals. In this paper, we review the current state-of-the-art of H-PDLCs including the materials used to date, the grating formation dynamics and simulations, the optimization of electro-optical properties, the photonic applications, and the issues existed in H-PDLCs.

  11. Modulation of shape and polarization of beam using a liquid crystal q-plate that is fabricated via photo-alignment.

    Science.gov (United States)

    Huang, Yao-Han; Ko, Shih-Wei; Li, Ming-Shian; Chu, Shu-Chun; Fuh, Andy Y-G

    2013-05-06

    A liquid crystal (LC) device, called a "q-plate" (QP), which is based on axially symmetric photo-alignment was investigated. The electrically tunable LC QP device could be modulated to control the shape and polarization of a linearly polarized Gaussian laser beam that propagated through it. The intensity profile and polarization distribution were simulated by MATLAB and 1D-DIMOS. The results of the simulation were consistent with experimental findings. In the fabricated electrically tunable LC QP device, switching between different beam-profile configurations can be realized by applying a voltage. Moreover, the fabrication of an LC QP is relatively simple, and the device has potential for such practical applications as beam shape modulators and spatial polarization converters use in diffractive optics and imaging systems.

  12. Electrothermally Tunable Bridge Resonator

    KAUST Repository

    Hajjaj, Amal Z.

    2016-12-05

    This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator compressed by a force due to electrothermal actuation. We demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally, by passing a DC current through it. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and to simulation results of a multi-physics finite-element model. A good agreement is found among all the results.

  13. Tunable double fano resonances based on bilayer graphene/metal gratings

    Science.gov (United States)

    Lu, Yanan; Yang, Guofeng; Yan, Pengfei; Cao, Jintao

    2017-11-01

    A novel structure with bilayer hybrid graphene/metal (G/M) gratings to realize tunable double Fano resonances has been proposed. Different band gaps can be obtained by applying voltages on the bilayer graphenes. Due to the tunability of the hybrid structure, two different resonances are separately tuned under various parametric conditions. The Fano resonances are produced by the interaction between the metal and graphene gratings, the related mechanism is investigated by the electric field distribution and transmission phase. The superior characteristics of the separately tunable double Fano resonances indicate a promising application in THz optical devices.

  14. Zn x Cd1‑x S tunable band structure-directing photocatalytic activity and selectivity of visible-light reduction of CO2 into liquid solar fuels

    Science.gov (United States)

    Tang, Lanqin; Kuai, Libang; Li, Yichang; Li, Haijin; Zhou, Yong; Zou, Zhigang

    2018-02-01

    A series of Zn x Cd1‑x S monodispersed nanospheres were successfully synthesized with tunable band structures. As-prepared Zn x Cd1‑x S solid solutions show much enhanced photocatalytic efficiency for CO2 photoreduction in aqueous solutions under visible light irradiation, relative to pure CdS analog. Methanol (CH3OH) and acetaldehyde (CH3CHO) are the major products of CO2 photoreduction for the solid solutions with x = 0, 0.2, and 0.5. Interestingly, Zn0.8Cd0.2S photocatalyst with a wide band gap can also additionally generate ethanol (CH3CH2OH) besides CH3OH and CH3CHO. The balance between the band structure-directing redox capacity and light absorption should be considered to influence both product yield and selectivity of CO2 photoreduction. The possible photoreduction mechanism was tentatively proposed.

  15. Electrowetting on liquid-infused film (EWOLF): Complete reversibility and controlled droplet oscillation suppression for fast optical imaging

    Science.gov (United States)

    Hao, Chonglei; Liu, Yahua; Chen, Xuemei; He, Yuncheng; Li, Qiusheng; Li, K. Y.; Wang, Zuankai

    2014-10-01

    Electrowetting on dielectric (EWOD) has emerged as a powerful tool to electrically manipulate tiny individual droplets in a controlled manner. Despite tremendous progress over the past two decades, current EWOD operating in ambient conditions has limited functionalities posing challenges for its applications, including electronic display, energy generation, and microfluidic systems. Here, we demonstrate a new paradigm of electrowetting on liquid-infused film (EWOLF) that allows for complete reversibility and tunable transient response simultaneously. We determine that these functionalities in EWOLF are attributed to its novel configuration, which allows for the formation of viscous liquid-liquid interfaces as well as additional wetting ridges, thereby suppressing the contact line pinning and severe droplet oscillation encountered in the conventional EWOD. Finally, by harnessing these functionalities demonstrated in EWOLF, we also explore its application as liquid lens for fast optical focusing.

  16. Electrostatically Tunable Nanomechanical Shallow Arches

    KAUST Repository

    Kazmi, Syed N. R.

    2017-11-03

    We report an analytical and experimental study on the tunability of in-plane doubly-clamped nanomechanical arches under varied DC bias conditions at room temperature. For this purpose, silicon based shallow arches are fabricated using standard e-beam lithography and surface nanomachining of a highly conductive device layer on a silicon-on-insulator (SOI) wafer. The experimental results show good agreement with the analytical results with a maximum tunability of 108.14% for 180 nm thick arch with a transduction gap of 1 μm between the beam and the driving/sensing electrodes. The high tunability of shallow arches paves the ways for highly tunable band pass filtering applications in high frequency range.

  17. Tunable on chip optofluidic laser

    DEFF Research Database (Denmark)

    Bakal, Avraham; Vannahme, Christoph; Kristensen, Anders

    2016-01-01

    On chip tunable laser is demonstrated by realizing a microfluidic droplet array. The periodicity is controlled by the pressure applied to two separate inlets, allowing to tune the lasing frequency over a broad spectral range.......On chip tunable laser is demonstrated by realizing a microfluidic droplet array. The periodicity is controlled by the pressure applied to two separate inlets, allowing to tune the lasing frequency over a broad spectral range....

  18. Spectral and Radiometric Calibration Using Tunable Lasers

    Science.gov (United States)

    McCorkel, Joel (Inventor)

    2017-01-01

    A tunable laser system includes a tunable laser, an adjustable laser cavity for producing one or more modes of laser light emitted from the tunable laser, a first optical parametric oscillator positioned in a light path of the adjustable laser cavity, and a controller operable to simultaneously control parameters of at least the tunable laser, the first optical parametric oscillator, and the adjustable laser cavity to produce a range of wavelengths emitted from the tunable laser system. A method of operating a tunable laser system includes using a controller to simultaneously control parameters of a tunable laser, an adjustable laser cavity for producing one or more modes of laser light emitted from the tunable laser, and a first optical parametric oscillator positioned in a light path of the adjustable laser cavity, to produce a range of wavelengths emitted from the tunable laser system.

  19. Economic and environmental evaluation of coal-and-biomass-to-liquids-and-electricity plants equipped with carbon capture and storage

    Science.gov (United States)

    Among various clean energy technologies, one innovative option for reducing greenhouse gas (GHG) emissions involves pairing carbon capture and storage (CCS) with the production of synthetic fuels and electricity from co-processed coal and biomass. With a relatively pure CO2 strea...

  20. New devices for flow measurements: Hot film and burial wire sensors, infrared imagery, liquid crystal, and piezo-electric model

    Science.gov (United States)

    Mcree, Griffith J., Jr.; Roberts, A. Sidney, Jr.

    1991-01-01

    An experimental program aimed at identifying areas in low speed aerodynamic research where infrared imaging systems can make significant contributions is discussed. Implementing a new technique, a long electrically heated wire was placed across a laminar flow. By measuring the temperature distribution along the wire with the IR imaging camera, the flow behavior was identified.

  1. Polarization modulation by tunable electromagnetic metamaterial reflector/absorber

    OpenAIRE

    Zhu, Bo; Zhao, Yijun Feng Junming; Huang, Ci; Wang, Zhengbin; Jiang, Tian

    2010-01-01

    We propose a polarization modulation scheme of electromagnetic (EM) waves through reflection of a tunable metamaterial reflector/absorber. By constructing the metamaterial with resonant unit cells coupled by diodes, we demonstrate that the EM reflections for orthogonal polarized incident waves can be tuned independently by adjusting the bias voltages on the corresponding diodes. Owing to this feature, the reflected EM waves can be electrically controlled to a linear polarization with continuo...

  2. Photodynamics and Physics behind Tunable Solid-State Lasers

    Science.gov (United States)

    1991-02-28

    Ultrafast Spectroscopy and Lasers Departments of Physics and Electrical Enginnering City College of New York 138th St. at Convent Avenue, New York...fiber optic communications along with basic scienuiic research. In this article, we will introduce a new tunable solid- state laser system : Chromium...a well de- fined wavelength of 694.3nm. Four different hosts are necessary to cover the 700-UOOnm range. The Cr>~: MgjSiO, system extends the range

  3. Ionogels Based on Poly(methyl methacrylate and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties

    Directory of Open Access Journals (Sweden)

    Kerstin Zehbe

    2016-03-01

    Full Text Available Ionogels (IGs based on poly(methyl methacrylate (PMMA and the metal-containing ionic liquids (ILs bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II, tetrachloride cobaltate(II, and tetrachlorido manganate(II have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic properties of IGs.

  4. Selected properties of high velocity oxy liquid fuel (HVOLF - sprayed nanocrystalline WC-CO INFRALLOYTM S7412 coatings modified by high energy electric pulse

    Directory of Open Access Journals (Sweden)

    S. Spadło

    2017-01-01

    Full Text Available The paper presents a brief study of selected properties of HVOLF-sprayed nanocrystalline WC-Co InfralloyTM S7412 coatings modified by the application of a high energy electric pulse. The anti-wear coatings were applied on carbon steel with the use of High Velocity Oxy Liquid Fuel (HVOLF spraying system TAFA – JP-5000. The process was modified by the application of the SST France & Vision Lasertechnik device WS 7000 S. The resultant type of coatings may be applied to increase the abrasive wear resistance of tools and machine parts. The properties of the powders and coatings were studied using metallographic methods and EDS analyses. The microhardness and nanohardness of the resultant layers were measured and Young’s modulus of elasticity was determined.

  5. Influence of methyl red as a dopant on the electrical properties and device performance of liquid crystals.

    Science.gov (United States)

    Wu, Po-Chang; Hou, Chien-Tsung; Hsiao, Yu-Cheng; Lee, Wei

    2014-12-15

    The ionic effect in nematic liquid-crystal (LC) cells containing the azo dye methyl red was investigated by means of dielectric spectroscopy, measurements of voltage holding ratio (VHR) and ultraviolet/visible absorption spectroscopy. The experimental results indicated that incorporating a minute amount of the methyl red (< 0.03 wt%) in the LC host leads to the suppression of the ionic effect caused by impurity ions. Practically, the doped LC cells with a dye content of 0.02 wt% showed improved VHR and promoted lifetime by 15% and 180%, respectively, in virtually no expense of the optical transmittance.

  6. Tunable Broadband Printed Carbon Transparent Conductor

    Science.gov (United States)

    Xu, Yue; Wan, Jiayu

    Transparent conductors have been widely applied in solar cells, transparent smart skins, and sensing/imaging antennas, etc. Carbon-based transparent conductor has attracted great attention for its low cost and broad range transparency. Ion intercalation has been known to highly dope graphitic materials, thereby tuning materials' optoelectronic properties. For the first time, we successfully tune the optical transmittance of a reduced graphene oxide (RGO)/CNT network from mid-IR range to visible range by means of Li-ion intercalation/deintercalation. We also observed a simultaneous increase of the electrical conductivity with the Li-ion intercalation. This printed carbon hybrid thin film was prepared through all solution processes and was easily scalable. This study demonstrates the possibility of using ion intercalation for low cost, tunable broadband transparent conductors.

  7. Tunable diode laser optogalvanic spectroscopy of molecules

    Science.gov (United States)

    Webster, C. R.; Menzies, R. T.

    1983-01-01

    The laser optogalvanic (LOG) technique for studying molecular spectra has been extended for the first time to the infrared wavelength region. Portions of the NH3 nu-2 band at 9.5 microns and the NO2 nu-3 band at 6.2 microns have been recorded at Doppler-limited resolution using CW tunable diode lasers to probe dc electrical discharges in pure NH3 and an NO2/He gas mixture. Using adjustable electrode positions and an orthogonal geometry between the probe laser and the discharge axis, two contributions to the optogalvanic signal are identified: one which corresponds to an increase in discharge impedance and is seen only for irradiation of the negative glow region; and a second which corresponds to a decrease in discharge impedance and is seen for irradiation of all other discharge regions.

  8. Tunable terahertz metamaterial with a graphene reflector

    Science.gov (United States)

    Deng, Guangsheng; Xia, Tianyu; Yang, Jun; Qiu, Longzhen; Yin, Zhiping

    2016-11-01

    An hybrid graphene/metamaterial(MM) structure by directly depositing single-layer graphene on bottom of a SiO2/Si substrate of the electric ring resonators is proposed and theoretically investigated in the terahertz(THz) region. Our calculated results show that the presence of the graphene strongly changes the THz MM transmittance in the frequency range from 0.1 to 1.7 THz, and a modulation depth of 80% or above is reached on the whole frequency range except a narrow band. The tunability of the proposed structure is mainly dependent on the transmission bands between two neighboring resonance frequencies, which is different from the conventional graphene MM structure based on single resonance dip. Moreover, the energy absorption in graphene layer plays an important role in THz wave modulation. This easy-to-fabricate structure shows potential applications in developing broadband transmission modulators and sensors.

  9. Tunable Multiband Microwave Photonic Filters

    Directory of Open Access Journals (Sweden)

    Mable P. Fok

    2017-11-01

    Full Text Available The increasing demand for multifunctional devices, the use of cognitive wireless technology to solve the frequency resource shortage problem, as well as the capabilities and operational flexibility necessary to meet ever-changing environment result in an urgent need of multiband wireless communications. Spectral filter is an essential part of any communication systems, and in the case of multiband wireless communications, tunable multiband RF filters are required for channel selection, noise/interference removal, and RF signal processing. Unfortunately, it is difficult for RF electronics to achieve both tunable and multiband spectral filtering. Recent advancements of microwave photonics have proven itself to be a promising candidate to solve various challenges in RF electronics including spectral filtering, however, the development of multiband microwave photonic filtering still faces lots of difficulties, due to the limited scalability and tunability of existing microwave photonic schemes. In this review paper, we first discuss the challenges that were facing by multiband microwave photonic filter, then we review recent techniques that have been developed to tackle the challenge and lead to promising developments of tunable microwave photonic multiband filters. The successful design and implementation of tunable microwave photonic multiband filter facilitate the vision of dynamic multiband wireless communications and radio frequency signal processing for commercial, defense, and civilian applications.

  10. Exploiting dimensionality and defect mitigation to create tunable microwave dielectrics.

    Science.gov (United States)

    Lee, Che-Hui; Orloff, Nathan D; Birol, Turan; Zhu, Ye; Goian, Veronica; Rocas, Eduard; Haislmaier, Ryan; Vlahos, Eftihia; Mundy, Julia A; Kourkoutis, Lena F; Nie, Yuefeng; Biegalski, Michael D; Zhang, Jingshu; Bernhagen, Margitta; Benedek, Nicole A; Kim, Yongsam; Brock, Joel D; Uecker, Reinhard; Xi, X X; Gopalan, Venkatraman; Nuzhnyy, Dmitry; Kamba, Stanislav; Muller, David A; Takeuchi, Ichiro; Booth, James C; Fennie, Craig J; Schlom, Darrell G

    2013-10-24

    The miniaturization and integration of frequency-agile microwave circuits--relevant to electronically tunable filters, antennas, resonators and phase shifters--with microelectronics offers tantalizing device possibilities, yet requires thin films whose dielectric constant at gigahertz frequencies can be tuned by applying a quasi-static electric field. Appropriate systems such as BaxSr1-xTiO3 have a paraelectric-ferroelectric transition just below ambient temperature, providing high tunability. Unfortunately, such films suffer significant losses arising from defects. Recognizing that progress is stymied by dielectric loss, we start with a system with exceptionally low loss--Srn+1TinO3n+1 phases--in which (SrO)2 crystallographic shear planes provide an alternative to the formation of point defects for accommodating non-stoichiometry. Here we report the experimental realization of a highly tunable ground state arising from the emergence of a local ferroelectric instability in biaxially strained Srn+1TinO3n+1 phases with n ≥ 3 at frequencies up to 125 GHz. In contrast to traditional methods of modifying ferroelectrics-doping or strain-in this unique system an increase in the separation between the (SrO)2 planes, which can be achieved by changing n, bolsters the local ferroelectric instability. This new control parameter, n, can be exploited to achieve a figure of merit at room temperature that rivals all known tunable microwave dielectrics.

  11. Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} (R=Sm, Gd, Ho) alloys in liquid and amorphous states

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation); Svec, P.; Svec, P.; Janickovic, D. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Sidorova, E. [Plekhanov Russian University of Economics, Moscow (Russian Federation); Son, L. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation)

    2016-06-15

    Electrical resistivity and magnetic susceptibility of Al{sub 86}Ni{sub 8}Sm{sub 6}, Al{sub 86}Ni{sub 8}Gd{sub 6} and Al{sub 86}Ni{sub 8}Ho{sub 6} alloys are studied in a wide temperature range including amorphous, crystalline and liquid states. The negative value of resistivity temperature coefficient in amorphous ribbons is explained by the structural separation starting much before the beginning of their crystallization. The effective magnetic moments per Gd and Ho atoms are found to be essentially lower than for R{sup 3+} ions. The results are discussed in supposition of directed bonds between rare earth and aluminum atoms. - Highlights: • Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} alloys are studied experimentally. • The negative value of rtc in amorphous ribbons is explained. • The effective magnetic moments per Gd and Ho are found to be lower than for R{sup 3+} ions.

  12. Synthesis and characterization of magnetic of Ni/ABS nanocomposites by electrical explosion of wire in liquid and solution blending methods

    Science.gov (United States)

    Thuyet-Nguyen, Minh; Hai-Nguyen, Hong; Kim, Won Joo; Kim, Ho Yoon; Kim, Jin-Chun

    2017-03-01

    Nanomaterials have attracted great attention from chemists, physicists and materials scientists because of their application benefits and special properties. Thermoplastics have been used in many applications such as molding of non-electrical components, conducting, magnetic field and 3D printing. Nanocomposites are known as a material which blends the best properties of components, a high performance material exhibits unusual property combinations and unique design possibilities. In this research, we focused to investigate and report primary results in the synthesis of magnetic nanocomposites based on acrylonitrile butadiene styrene (ABS), which are useful and important thermoplastics. Nickel nanopowder was prepared by electrical explosion of wire in a liquid were used as magnetic component. The composites were prepared by following steps, first the obtained Ni nanopowders were incorporated into the ABS matrix via a solution blending method (drop-casting), and then the solvent was evaporated. The characterizations of obtaining composites were analyzed by field emission scanning electron microscopy, X-Ray Diffraction analysis and vibrating sample magnetometer.

  13. Field-effect induced tunability in hyperbolic metamaterials

    Science.gov (United States)

    Papadakis, Georgia T.; Atwater, Harry A.

    2015-11-01

    We demonstrate that use of the field effect enables tuning of the effective optical parameters of a layered hyperbolic metamaterial at optical frequencies. Field-effect gating electrically modulates the permittivity in transparent conductive oxides via changes in the carrier density. These permittivity changes lead to active modulation of the effective electromagnetic parameters along with active control of the anisotropic dispersion surface of hyperbolic metamaterials and enable the opening and closing of photonic band gaps. Tunability of the effective electric permittivity and magnetic permeability also leads to topological transitions in the optical dispersion characteristics.

  14. Self-Affine Graphene Metasurfaces for Tunable Broadband Absorption

    Science.gov (United States)

    Wu, Pin Chieh; Papasimakis, Nikitas; Tsai, Din Ping

    2016-10-01

    Graphene has emerged as a promising platform for THz metasurfaces supporting electrically tunable deep-subwavelength plasmonic excitations. Here, we introduce a broadband graphene metasurface based on the Hilbert curve, a continuous, space-filling fractal. We demonstrate the enhancement of graphene absorption over a broad frequency band (0.5-60 THz) with an average absorption level exceeding 20%. Owing to the continuous nature of the metasurface patterns, both the absorption level and the bandwidth can be controlled electrically by varying the graphene charge-carrier concentration.

  15. Parametric infrared tunable laser system

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.; Sutter, J. R.

    1980-01-01

    A parametric tunable infrared laser system was built to serve as transmitter for the remote detection and density measurement of pollutant, poisonous, or trace gases in the atmosphere. The system operates with a YAG:Nd laser oscillator amplifier chain which pumps a parametric tunable frequency converter. The completed system produced pulse energies of up to 30 mJ. The output is tunable from 1.5 to 3.6 micrometers at linewidths of 0.2-0.5 /cm (FWHM), although the limits of the tuning range and the narrower line crystals presently in the parametric converter by samples of the higher quality already demonstrated is expected to improve the system performance further.

  16. Complex risk analysis for loss of electric power in liquid metal nuclear reactor by system dynamics (SD) method

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Tae Ho [Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering

    2012-07-15

    The power stabilization of the nuclear power plants (NPPs) is investigated in the aspect of the liquid metal coolant. The quantification of the risk analysis is performed by the system dynamics (SD) method which is processed by the feedback and accumulation complex algorithms. The Vensim software package is used for the simulations, which is supported by the Monte-Carlo method. There are 2 kinds of considerations as the economic and safety properties. The result shows the stability of the operations when the power can be decided. This shows the higher efficiency of the reactor. The failure frequency is 16/60 = 27%. In the event of Power Stabilized, the failure event is in the quite lower frequency rate. The commercial use of the reactor is important in the operations. (orig.)

  17. Tunable Microfluidic Microlasers

    Science.gov (United States)

    2011-09-01

    Francesco Simoni Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio Università Politecnica delle Marche Via Brecce Bianche, 60131...circuits, in order to point out advantages and drawbacks of different experimental techniques. The alignment of liquid crystal in microfluidic...Lasing was detected through an optical fiber connected to a spectrometer. A preliminary experimental result is reported in fig. 13 where the light

  18. Tunable superluminal propagation on a silicon microchip.

    Science.gov (United States)

    Manipatruni, Sasikanth; Dong, Po; Xu, Qianfan; Lipson, Michal

    2008-12-15

    We demonstrate tunable superluminal propagation in a silicon microphotonic device in a solid-state room-temperature device of tens of micrometers in dimension allowing easy integration with high-bandwidth room-temperature systems. We achieve tunable negative delays up to 85 ps and effective group indices tunable between -1158 and -312.

  19. Widely tunable terahertz source based on intra-cavity frequency mixing in quantum cascade laser arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Aiting; Jung, Seungyong; Jiang, Yifan; Kim, Jae Hyun; Belkin, Mikhail A., E-mail: mbelkin@ece.utexas.edu [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Vijayraghavan, Karun [Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); ATX Photonics, 10100 Burnet Rd., Austin, Texas 78758 (United States)

    2015-06-29

    We demonstrate a compact monolithic terahertz source continuously tunable from 1.9 THz to 3.9 THz with the maximum peak power output of 106 μW at 3.46 THz at room temperature. The source consists of an array of 10 electrically tunable quantum cascade lasers with intra-cavity terahertz difference-frequency generation. To increase fabrication yield and achieve high THz peak power output in our devices, a dual-section current pumping scheme is implemented using two electrically isolated grating sections to independently control gain for the two mid-IR pumps.

  20. 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...

  1. Investigation of microstructural evolution and electrical properties for Ni-Sn transient liquid-phase sintering bonding

    Science.gov (United States)

    Feng, Hong-Liang; Huang, Ji-Hua; Yang, Jian; Zhou, Shao-Kun; Zhang, Rong; Wang, Yue; Chen, Shu-Hai

    2017-11-01

    Ni/Ni-Sn/Ni sandwiched simulated package structures were successfully bonded under low temperature and low pressure by Ni-Sn transient liquid-phase sintering bonding. The results show that, after isothermally holding for 240 min at 300 °C and 180 min at 340 °C, Sn was completely transformed into Ni3Sn4 intermetallic compounds. When the Ni3Sn4 phases around Ni particles were pressed together, the porosity of the bonding layer increased, which obviously differed from the normal sintering densification process. With further analysis of this phenomenon, it was found that large volume shrinkage (14.94% at 340 °C) occurred when Ni reacted with Sn to form Ni3Sn4, which caused void formation. A mechanistic model of the microstructural evolution in the bonding layer was proposed. Meanwhile, the resistivity of the bonding layer was measured and analyzed by using the four-probe method; the microstructural evolution was well reflected by the resistivity of the bonding layer. The relationship between the resistivity and microstructure was also discussed in detail.[Figure not available: see fulltext.

  2. Tunable on chip optofluidic laser

    DEFF Research Database (Denmark)

    Bakal, Avraham; Vannahme, Christoph; Kristensen, Anders

    2015-01-01

    A chip scale tunable laser in the visible spectral band is realized by generating a periodic droplet array inside a microfluidic channel. Combined with a gain medium within the droplets, the periodic structure provides the optical feedback of the laser. By controlling the pressure applied to two...

  3. Graphene induced tunable and polarization-insensitive broadband metamaterial absorber

    Science.gov (United States)

    Zhang, Yuping; Li, Yue; Cao, Yanyan; Liu, Yuanzhong; Zhang, Huiyun

    2017-01-01

    We design a tunable and broadband metamaterial absorber in the mid-infrared region based on graphene. The unit cell of the proposed metamaterial absorber consists of circular gold patches, which coupled with a graphene layer, and are separated by a dielectric spacer from the gold film on the bottom. The absorption bandwidth is effectively extended by patterning multi-circular gold patches of different dimension elements with appropriate geometrical parameters in a co-plane. The metamaterial absorber achieves its frequency tunable characteristics via changing the applied voltage or chemical doping to manipulate graphene's Fermi energy. We analyzed the surface current distributions and the distributions of the z-component electric field for understanding the absorption mechanism. Moreover, the design principle here could be regarded as a template to extend bandwidth by introducing more circular patches into each unit cell. Our design has potential applications in various fields of stealth technology, photovoltaic devices, sensors, and broadband communication.

  4. Electric-Field-Tunable Ferroelastic Control of Nonvolatile Resistivity and Ferromagnetic Switching in Multiferroic La0.67Ca0.33MnO3/[PbMg1/3Nb2/3O3] 0.7[PbTiO3]0.3 Heterostructures

    Science.gov (United States)

    Zheng, Ming; Zheng, Ren-Kui

    2016-04-01

    The electric-field-modulated nonvolatile resistivity and magnetization switching in elastically coupled La0.67Ca0.33MnO3 films grown on (111)-oriented 0.7 Pb (Mg1 /3Nb2 /3)O3-0.3 PbTiO3 substrates is achieved through the ferroelastic effect. By taking advantage of the 180° ferroelectric and non-180° ferroelastic domain switching, we identify that such changes in order parameters stem from domain-switching-induced strain rather than accumulation or depletion of charge carriers at the interface. Specifically, the strong correlation between the ferroelastic strain and the magnetic field is manifested not only by the strain-tunable magnetoresistance effect but also by the magnetically manipulated strain effect, which is essentially driven by the electronic phase separation. These findings present a potential strategy for elucidating the essential physics of the ferroelastic-strain effect and delivering prototype devices for energy-efficient and nonvolatile information storage.

  5. Electrothermo-optical effect in liquid crystals and its applications

    Science.gov (United States)

    Hsiao, Yu-Cheng; Lee, Wei

    2017-02-01

    Electro-optical effects in liquid crystals (LCs) have been widely utilized in many optical components and photonic devices, thanks to the anisotropic media that can be easily manipulated by an electric field to modulate the light. In general, dielectric heating in LC applications is negligible because their orientational dielectric relaxations occur at high frequencies. Here we focus on a dual-frequency LC characterized by its much lower relaxation frequency. The fieldinduced heat strongly affects the LC ordering and optical properties. The electrothermo-optical effect reveals an unusual behavior compared with the well-known electro-optical effect in regular LCs. Based on the electrothermo-optical effect, some applications such as optical modulators or tunable optical shutters are demonstrated.

  6. Strong tissue glue with tunable elasticity.

    Science.gov (United States)

    Kelmansky, Regina; McAlvin, Brian J; Nyska, Abraham; Dohlman, Jenny C; Chiang, Homer H; Hashimoto, Michinao; Kohane, Daniel S; Mizrahi, Boaz

    2017-04-15

    Many bio-adhesive materials adhere weakly to tissue due to their high water content and weak structural integrity. Others provide desirable adhesive strength but suffer from rigid structure and lack of elasticity after administration. We have developed two water-free, liquid four-armed PEG pre-polymers modified with NHS or with NH 2 end groups which upon mixing changed from liquids to an elastic solid. The sealant and adhesive properties increased with the amount of the %v/v PEG 4 -NHS pre-polymer, and achieved adhesive properties comparable to those of cyanoacrylate glues. All mixtures showed minimal cytotoxicity in vitro. Mixtures of 90%v/v PEG 4 -NHS were retained in the subcutaneous space in vivo for up to 14days with minimal inflammation. This material's combination of desirable mechanical properties and biocompatibility has potential in numerous biomedical applications. Many bio-adhesive materials adhere weakly to tissue (e.g. hydrogels) due to their high water content and weak structural integrity. Others provide desirable mechanical properties but suffer from poor biocompatibility (e.g. cyanoacrylates). This study proposes a new concept for the formation of super strong and tunable tissue glues. Our bio-materials' enhanced performance is the product of new neat (without water or other solvents) liquid polymers that solidify after administration while allowing interactions with the tissue. Moreover, the elastic modulus of these materials could easily be tuned without compromising biocompatibility. This system could be an attractive alternative to sutures and staples since it can be applied more quickly, causes less pain and may require less equipment while maintaining the desired adhesion strength. Copyright © 2017 Acta Materialia Inc. All rights reserved.

  7. Novel optical devices based on the tunable refractive index of magnetic fluid and their characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yong, E-mail: zhaoyong@ise.neu.edu.cn [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Zhang Yuyan [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China); Shenyang Institute of Engineering, Shenyang 110136 (China); Lv Riqing; Wang Qi [College of Information Science and Engineering, Northeastern University, Shenyang 110819 (China)

    2011-12-15

    As a new type of functional material, magnetic fluid (MF) is a stable colloid of magnetic nanoparticles, dressed with surfactant and dispersed in the carrier liquid uniformly. The MF has many unique optical properties, and the most important one is its tunable refractive index property. This paper summarizes the properties of the MF refractive index and the related optical devices. The refractive index can be easily controlled by external magnetic field, temperature, and so on. But the tunable refractive index of MF has a relaxation effect. As a result, the response time is more than milliseconds and the MF is only suitable for low speed environment. Compared with the traditional optical devices, the magnetic fluid based optical devices have the tuning ability. Compared with the tunable optical devices (the electro-optic devices (LiNbO{sub 3}) of more than 10 GHz modulation speed, acoustic-optic devices (Ge) of more than 20 MHz modulation speed), the speed of the magnetic fluid based optical devices is low. Now there are many applications of magnetic fluid based on the refractive index in the field of optical information communication and sensing technology, such as tunable beam splitter, optical-fiber modulator, tunable optical gratings, tunable optical filter, optical logic device, tunable interferometer, and electromagnetic sensor. With the development of the research and application of magnetic fluid,a new method, structure and material to improve the response time can be found, which will play an important role in the fields of optical information communication and sensing technology. - Highlights: > Magnetic fluid is a new type of functional material, which has many unique optical properties. > We summarize the tunable refractive index property and the related optical devices. > Refractive index can be easily controlled by external magnetic field, temperature and so on. > There are many applications in the field of optical communication and sensing technology

  8. The Influence of Anion Shape on the Electrical Double Layer Microstructure and Capacitance of Ionic Liquids-Based Supercapacitors by Molecular Simulations

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2017-02-01

    Full Text Available Room-temperature ionic liquids (RTILs are an emerging class of electrolytes for supercapacitors. In this work, we investigate the effects of different supercapacitor models and anion shape on the electrical double layers (EDLs of two different RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonylimide ([Emim][Tf2N] and 1-ethyl-3-methylimidazolium 2-(cyanopyrrolide ([Emim][CNPyr] by molecular dynamics (MD simulation. The EDL microstructure is represented by number densities of cations and anions, and the potential drop near neutral and charged electrodes reveal that the supercapacitor model with a single electrode has the same EDL structure as the model with two opposite electrodes. Nevertheless, the employment of the one-electrode model without tuning the bulk density of RTILs is more time-saving in contrast to the two-electrode one. With the one-electrode model, our simulation demonstrated that the shapes of anions significantly imposed effects on the microstructure of EDLs. The EDL differential capacitance vs. potential (C-V curves of [Emim][CNPyr] electrolyte exhibit higher differential capacitance at positive potentials. The modeling study provides microscopic insight into the EDLs structure of RTILs with different anion shapes.

  9. Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

    Science.gov (United States)

    Obeidat, Amr M.

    Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also

  10. Intra-molecular coupling as a mechanism for a liquid-liquid phase transition

    OpenAIRE

    Franzese, Giancarlo; Marques, Manuel I.; Stanley, H. Eugene

    2001-01-01

    We study a model for water with a tunable intra-molecular interaction $J_\\sigma$, using mean field theory and off-lattice Monte Carlo simulations. For all $J_\\sigma\\geq 0$, the model displays a temperature of maximum density.For a finite intra-molecular interaction $J_\\sigma > 0$,our calculations support the presence of a liquid-liquid phase transition with a possible liquid-liquid critical point for water, likely pre-empted by inevitable freezing. For J=0 the liquid-liquid critical point dis...

  11. A tunable, linac based, intense, broad-band THz source forpump-probe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Schmerge, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Adolphsen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Corbett, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dolgashev, V. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Durr, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fazio, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fisher, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Frisch, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gaffney, K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Guehr, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hastings, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hettel, B. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hoffmann, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hogan, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Holtkamp, N. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, X. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Huang, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Kirchmann, P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); LaRue, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Limborg, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lindenberg, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Loos, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Maxwell, T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Nilsson, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Raubenheimer, T. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Reis, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Ross, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shen, Z. -X. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stupakov, G. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tantawi, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tian, K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wu, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Xiang, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Yakimenko, V. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-02

    We propose an intense THz source with tunable frequency and bandwidth that can directly interact with the degrees of freedom that determine the properties of materials and thus provides a new tool for controlling and directing these ultrafast processes as well as aiding synthesis of new materials with new functional properties. This THz source will broadly impact our understanding of dynamical processes in matter at the atomic-scale and in real time. Established optical pumping schemes using femtosecond visible frequency laser pulses for excitation are extended into the THz frequency regime thereby enabling resonant excitation of bonds in correlated solid state materials (phonon pumping), to drive low energy electronic excitations, to trigger surface chemistry reactions, and to all-optically bias a material with ultrashort electric fields or magnetic fields. A linac-based THz source can supply stand-alone experiments with peak intensities two orders of magnitude stronger than existing laser-based sources, but when coupled with atomic-scale sensitive femtosecond x-ray probes it opens a new frontier in ultrafast science with broad applications to correlated materials, interfacial and liquid phase chemistry, and materials in extreme conditions.

  12. Tailoring the nature and strength of electron-phonon interactions in the SrTiO$_3$(001) two-dimensional electron liquid

    OpenAIRE

    Wang, Z.; Mckeown Walker, Siobhan; Tamai, Anna; Wang, Y.; Ristic, Z.; Bruno, Flavio Yair; de la Torre, Alberto; Ricco, Sara; Plumb, N. C.; M. Shi; Hlawenka, P.; Sánchez-Barriga, J.; A. Varykhalov; Kim, T. K.; Hoesch, M.

    2015-01-01

    Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides1–4. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO3(001) surface5–7 to reveal a remarkably complex evolution of electron–phonon coupling with the tunable carrier density of this system. At low density, where superconductivity is found in the analogous 2DEL at the LaAlO3/SrTiO3 interface8–13, o...

  13. Tunable far-infrared spectroscopy

    Science.gov (United States)

    Evenson, K. M.; Jennings, D. A.; Petersen, F. R.

    1984-01-01

    Tunable, CW, far-infrared radiation has been generated by nonlinear mixing of radiation from two CO2 lasers in a metal-insulator-metal (MIM) diode. The FIR difference-frequency power radiated from the MIM diode antenna to a calibrated indium antimonide bolometer. Two-tenths of a microwatt of FIR power was generated by 250 mW from each of the CO2 lasers. The combination of lines from a waveguide CO2 laser, with its larger tuning range, with lines from CO2, N2O, and CO2 isotopic lasers promises complete coverage of the entire far-infrared band from 100 to 5000 GHz (3-200 per cm) with stepwise-tunable CW radiation. To demonstrate the usefulness of the technique, the J = 4-5 line of CO was observed at 567 GHz.

  14. Optofluidic tunable mode-locked fiber laser using a long-period grating integrated microfluidic chip.

    Science.gov (United States)

    Wang, Jie; Yao, Mian; Hu, Chengzhi; Ping Zhang, A; Shen, Yonghang; Tam, Hwa-Yaw; Wai, P K A

    2017-03-15

    An optofluidic tunable mode-locked fiber laser using a microfluidic chip integrated with long-period grating (LPG) is presented. The microfluidic chip enables ultrafine adjustment of the liquid's refractive index and, thus, LPG's spectrum via tuning the mixing ratio of the microfluidic flows. With such an optofluidic spectrum-tunable filter, the central wavelength of the mode-locked laser can be tuned continuously, while the mode-locking state is steadily maintained. The mode-locked pulses are measured with a pulse duration of 0.9 ps and repetition rate of 12.14 MHz, respectively. Moreover, bound solitons with variable soliton separations are experimentally demonstrated.

  15. On-Demand Spin–Orbit Interaction from Which-Layer Tunability in Bilayer Graphene

    Science.gov (United States)

    Khoo, Jun Yong; Morpurgo, Alberto F.; Levitov, Leonid

    2017-11-01

    Spin-orbit interaction (SOI) that is gate-tunable over a broad range is essential to exploiting novel spin phenomena. Achieving this regime has remained elusive because of the weakness of the underlying relativistic coupling and lack of its tunability in solids. Here we outline a general strategy that enables exceptionally high tunability of SOI through creating a which-layer spin-orbit field inhomogeneity in graphene multilayers. An external transverse electric field is applied to shift carriers between the layers with strong and weak SOI. Because graphene layers are separated by sub-nm scales, exceptionally high tunability of SOI can be achieved through a minute carrier displacement. A detailed analysis of the experimentally relevant case of bilayer graphene on a semiconducting transition metal dichalchogenide substrate is presented. In this system, a complete tunability of SOI amounting to its ON/OFF switching can be achieved. New opportunities for spin control are exemplified with electrically driven spin resonance and topological phases with different quantized intrinsic valley Hall conductivities.

  16. Nanoporous carbon tunable resistor/transistor and methods of production thereof

    Science.gov (United States)

    Biener, Juergen; Baumann, Theodore F; Dasgupta, Subho; Hahn, Horst

    2014-04-22

    In one embodiment, a tunable resistor/transistor includes a porous material that is electrically coupled between a source electrode and a drain electrode, wherein the porous material acts as an active channel, an electrolyte solution saturating the active channel, the electrolyte solution being adapted for altering an electrical resistance of the active channel based on an applied electrochemical potential, wherein the active channel comprises nanoporous carbon arranged in a three-dimensional structure. In another embodiment, a method for forming the tunable resistor/transistor includes forming a source electrode, forming a drain electrode, and forming a monolithic nanoporous carbon material that acts as an active channel and selectively couples the source electrode to the drain electrode electrically. In any embodiment, the electrolyte solution saturating the nanoporous carbon active channel is adapted for altering an electrical resistance of the nanoporous carbon active channel based on an applied electrochemical potential.

  17. Additive manufacturing of tunable lenses

    Science.gov (United States)

    Schlichting, Katja; Novak, Tobias; Heinrich, Andreas

    2017-02-01

    Individual additive manufacturing of optical systems based on 3D Printing offers varied possibilities in design and usage. In addition to the additive manufacturing procedure, the usage of tunable lenses allows further advantages for intelligent optical systems. Our goal is to bring the advantages of additive manufacturing together with the huge potential of tunable lenses. We produced tunable lenses as a bundle without any further processing steps, like polishing. The lenses were designed and directly printed with a 3D Printer as a package. The design contains the membrane as an optical part as well as the mechanical parts of the lens, like the attachments for the sleeves which contain the oil. The dynamic optical lenses were filled with an oil. The focal length of the lenses changes due to a change of the radius of curvature. This change is caused by changing the pressure in the inside of the lens. In addition to that, we designed lenses with special structures to obtain different areas with an individual optical power. We want to discuss the huge potential of this technology for several applications. Further, an appropriate controlling system is needed. Wéll show the possibilities to control and regulate the optical power of the lenses. The lenses could be used for illumination tasks, and in the future, for individual measurement tasks. The main advantage is the individuality and the possibility to create an individual design which completely fulfills the requirements for any specific application.

  18. Highly tunable NEMS shallow arches

    KAUST Repository

    Kazmi, Syed N. R.

    2017-11-30

    We report highly tunable nanoelectromechanical systems NEMS shallow arches under dc excitation voltages. Silicon based in-plane doubly clamped bridges, slightly curved as shallow arches, are fabricated using standard electron beam lithography and surface nanomachining of a highly conductive device layer on a silicon-on-insulator wafer. By designing the structures to have gap to thickness ratio of more than four, the mid-plane stretching of the nano arches is maximized such that an increase in the dc bias voltage will result into continuous increase in the resonance frequency of the resonators to wide ranges. This is confirmed analytically based on a nonlinear beam model. The experimental results are found to be in good agreement with that of the results from developed analytical model. A maximum tunability of 108.14% for a 180 nm thick arch with an initially designed gap of 1 μm between the beam and the driving/sensing electrodes is achieved. Furthermore, a tunable narrow bandpass filter is demonstrated, which opens up opportunities for designing such structures as filtering elements in high frequency ranges.

  19. Tunable terahertz absorption in graphene-based metamaterial

    Science.gov (United States)

    Zhang, Qinfei; Ma, Qixiang; Yan, Shitao; Wu, Fengmin; He, Xunjun; Jiang, Jiuxing

    2015-10-01

    One of the most important advantages of graphene is the capability of dynamically tuning its conductivity by means of chemical doping or gate voltage. Based on this property, we proposed a tunable graphene-based terahertz absorber composed of a periodically patterned graphene structure and a metal ground plane spaced by a thin SiO2 dielectric layer. Our calculated results show that a perfect absorption can be achieved by using a single layer of graphene-based metamaterial structure at a fixed Fermi energy level. Moreover, the calculated electric field and power loss distributions enable us to reveal the absorption mechanism of the designed absorber. More importantly, we found that the absorption peak can be dynamically controlled over a broadband frequency range by adjusting the gate voltage without re-optimizing or re-fabricating the physical structure. This work may provide a further step in the development of compact tunable devices, such as tunable sensors and absorbers, switches, and slow light devices.

  20. Polarization-independent actively tunable colour generation on imprinted plasmonic surfaces

    Science.gov (United States)

    Franklin, Daniel; Chen, Yuan; Vazquez-Guardado, Abraham; Modak, Sushrut; Boroumand, Javaneh; Xu, Daming; Wu, Shin-Tson; Chanda, Debashis

    2015-01-01

    Structural colour arising from nanostructured metallic surfaces offers many benefits compared to conventional pigmentation based display technologies, such as increased resolution and scalability of their optical response with structure dimensions. However, once these structures are fabricated their optical characteristics remain static, limiting their potential application. Here, by using a specially designed nanostructured plasmonic surface in conjunction with high birefringence liquid crystals, we demonstrate a tunable polarization-independent reflective surface where the colour of the surface is changed as a function of applied voltage. A large range of colour tunability is achieved over previous reports by utilizing an engineered surface which allows full liquid crystal reorientation while maximizing the overlap between plasmonic fields and liquid crystal. In combination with imprinted structures of varying periods, a full range of colours spanning the entire visible spectrum is achieved, paving the way towards dynamic pixels for reflective displays. PMID:26066375

  1. 1550-nm wavelength-tunable HCG VCSELs

    Science.gov (United States)

    Chase, Christopher; Rao, Yi; Huang, Michael; Chang-Hasnain, Connie

    2014-02-01

    We demonstrate wavelength-tunable VCSELs using high contrast gratings (HCGs) as the top output mirror on VCSELs, operating at 1550 nm. Tunable HCG VCSELs with a ~25 nm mechanical tuning range as well as VCSELs with 2 mW output power were realized. Error-free operation of an optical link using directly-modulated tunable HCG VCSELs transmitting at 1.25 Gbps over 18 channels spaced by 100 GHz and transmitted over 20 km of single mode fiber is demonstrated, showing the suitability of the HCG tunable VCSEL as a low cost source for WDM communications systems.

  2. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  3. Meta-structure and tunable optical device including the same

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghoon; Papadakis, Georgia Theano; Atwater, Harry

    2017-12-26

    A meta-structure and a tunable optical device including the same are provided. The meta-structure includes a plurality of metal layers spaced apart from one another, an active layer spaced apart from the plurality of metal layers and having a carrier concentration that is tuned according to an electric signal applied to the active layer and the plurality of metal layers, and a plurality of dielectric layers spaced apart from one another and each having one surface contacting a metal layer among the plurality of metal layers and another surface contacting the active layer.

  4. The AHA Moment: Assessment of the Redox Stability of Ionic Liquids Based on Aromatic Heterocyclic Anions (AHAs) for Nuclear Separations and Electric Energy Storage.

    Science.gov (United States)

    Shkrob, Ilya A; Marin, Timothy W

    2015-11-19

    Because of their extended conjugated bond network, aromatic compounds generally have higher redox stability than less saturated compounds. We conjectured that ionic liquids (ILs) consisting of aromatic heterocyclic anions (AHAs) may exhibit improved radiation and electrochemical stability. Such properties are important in applications of these ILs as diluents in radionuclide separations and electrolytes in the electric energy storage devices. In this study, we systematically examine the redox chemistry of the AHAs. Three classes of these anions have been studied: (i) simple 5-atom ring AHAs, such as the pyrazolide and triazolides, (ii) AHAs containing an adjacent benzene ring, and (iii) AHAs containing electron-withdrawing groups that were introduced to reduce their basicity and interaction with metal ions. It is shown that fragmentation in the reduced and oxidized states of these AHAs does not generally occur, and the two main products, respectively, are the H atom adduct and the imidyl radical. The latter species occurs either as an N σ-radical or as an N π-radical, depending on the length of the N-N bond, and the state that is stabilized in the solid matrix is frequently different from that having the lowest energy in the gas phase. In some instances, the formation of the sandwich π-stack dimer radical anions has been observed. For trifluoromethylated anions, H adduct formation did not occur; instead, there was facile loss of fluoride from their fluorinated groups. The latter can be problematic in nuclear separations, but beneficial in batteries. Overall, our study suggests that AHA-based ILs are viable candidates for use as radiation-exposed diluents and electrolytes.

  5. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  6. Widely tunable microwave phase shifter based on silicon-on-insulator dual-microring resonator

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Xue, Weiqi

    2010-01-01

    We propose and demonstrate tunable microwave phase shifters based on electrically tunable silicon-on-insulator microring resonators. The phase-shifting range and the RF-power variation are analyzed. A maximum phase-shifting range of 0~600° is achieved by utilizing a dual-microring resonator....... A quasi-linear phase shift of 360° with RF-power variation lower than 2dB and a continuous 270° phase shift without RF-power variation at a microwave frequency of 40GHz are also demonstrated....

  7. Photoresist Design for Elastomeric Light Tunable Photonic Devices

    Directory of Open Access Journals (Sweden)

    Sara Nocentini

    2016-06-01

    Full Text Available An increasing interest in tunable photonic structures is growing within the photonic community. The usage of Liquid Crystalline Elastomer (LCE structures in the micro-scale has been motivated by the potential to remotely control their properties. In order to design elastic photonic structures with a three-dimensional lithographic technique, an analysis of the different mixtures used in the micro-printing process is required. Previously reported LCE microstructures suffer damage and strong swelling as a limiting factor of resolution. In this article, we reported a detailed study on the writing process with four liquid crystalline photoresists, in which the percentage of crosslinker is gradually increased. The experiments reveal that exploiting the crosslinking degree is a possible means in which to obtain suspended lines with good resolution, quite good rigidity, and good elasticity, thereby preserving the possibility of deformation by light irradiation.

  8. Luminescent ion pairs with tunable emission colors for light-emitting devices and electrochromic switches.

    Science.gov (United States)

    Guo, Song; Huang, Tianci; Liu, Shujuan; Zhang, Kenneth Yin; Yang, Huiran; Han, Jianmei; Zhao, Qiang; Huang, Wei

    2017-01-01

    Most recently, stimuli-responsive luminescent materials have attracted increasing interest because they can exhibit tunable emissive properties which are sensitive to external physical stimuli, such as light, temperature, force, and electric field. Among these stimuli, electric field is an important external stimulus. However, examples of electrochromic luminescent materials that exhibit emission color change induced by an electric field are limited. Herein, we have proposed a new strategy to develop electrochromic luminescent materials based on luminescent ion pairs. Six tunable emissive ion pairs ( IP1-IP6 ) based on iridium(iii) complexes have been designed and synthesized. The emission spectra of ion pairs (IPs) show concentration dependence and the energy transfer process is very efficient between positive and negative ions. Interestingly, IP6 displayed white emission at a certain concentration in solution or solid state. Thus, in this contribution, UV-chip (365 nm) excited light-emitting diodes showing orange, light yellow and white emission colors were successfully fabricated. Furthermore, IPs displayed tunable and reversible electrochromic luminescence. For example, upon applying a voltage of 3 V onto the electrodes, the emission color of the solution of IP1 near the anode or cathode changed from yellow to red or green, respectively. Color tunable electrochromic luminescence has also been realized by using other IPs. Finally, a solid-film electrochromic switch device with a sandwiched structure using IP1 has been fabricated successfully, which exhibited fast and reversible emission color change.

  9. Long range surface plasmon resonance enhanced electro-optically tunable Goos-Hänchen shift and Imbert-Fedorov shift in ZnSe prism

    Science.gov (United States)

    Goswami, Nabamita; Kar, Aparupa; Saha, Ardhendu

    2014-11-01

    A new theoretical approach towards the tuning of Goos-Hänchen shift and Imbert-Fedorov shift for the reflected light beam is observed, designed and simulated in this paper through electro-optically tunable liquid crystal at an incident wavelength of 1550 nm within the communication window. Here the considered Kretschmann-Raether geometry comprises a ZnSe prism and a liquid crystal layer of E44 between two metal layers of silver, where with the application of electric field from (0-10) V electro-optically tuning of the Goos-Hänchen shift from 64.09 μm to -53.408 μm and the Imbert-Fedorov shift from 122.8 μm to -32.5 μm for a change in refractive index of the liquid crystal layer from 1.52-1.79 are envisaged. This idea expedites the scope of fine tuning in optical switching within the μm ranges.

  10. Microelectromechanically tunable multiband metamaterial with preserved isotropy.

    Science.gov (United States)

    Pitchappa, Prakash; Ho, Chong Pei; Qian, You; Dhakar, Lokesh; Singh, Navab; Lee, Chengkuo

    2015-06-26

    We experimentally demonstrate a micromachined reconfigurable metamaterial with polarization independent characteristics for multiple resonances in terahertz spectral region. The metamaterial unit cell consists of eight out-of-plane deformable microcantilevers placed at each corner of an octagon ring. The octagon shaped unit cell geometry provides the desired rotational symmetry, while the out-of-plane movable cantilevers preserves the symmetry at different configurations of the metamaterial. The metamaterial is shown to provide polarization independent response for both electrical inductive-capacitive (eLC) resonance and dipolar resonance at all states of actuation. The proposed metamaterial has a switching range of 0.16 THz and 0.37 THz and a transmission intensity change of more than 0.2 and 0.7 for the eLC and dipolar resonances, respectively for both TE and TM modes. Further optimization of the metal layer thickness, provides an improvement of up to 80% modulation at 0.57 THz. The simultaneously tunable dual band isotropic metamaterial will enable the realization of high performance electro-optic devices that would facilitate numerous terahertz applications such as compressive terahertz imaging, miniaturized terahertz spectroscopy and next generation high speed wireless communication possible in the near future.

  11. Tunable metallic conductance in ferroelectric nanodomains.

    Science.gov (United States)

    Maksymovych, Peter; Morozovska, Anna N; Yu, Pu; Eliseev, Eugene A; Chu, Ying-Hao; Ramesh, Ramamoorthy; Baddorf, Arthur P; Kalinin, Sergei V

    2012-01-11

    Metallic conductance in charged ferroelectric domain walls was predicted more than 40 years ago as the first example of an electronically active homointerface in a nonconductive material. Despite decades of research on oxide interfaces and ferroic systems, the metal-insulator transition induced solely by polarization charges without any additional chemical modification has consistently eluded the experimental realm. Here we show that a localized insulator-metal transition can be repeatedly induced within an insulating ferroelectric lead-zirconate titanate, merely by switching its polarization at the nanoscale. This surprising effect is traced to tilted boundaries of ferroelectric nanodomains, that act as localized homointerfaces within the perovskite lattice, with inherently tunable carrier density. Metallic conductance is unique to nanodomains, while the conductivity of extended domain walls and domain surfaces is thermally activated. Foreseeing future applications, we demonstrate that a continuum of nonvolatile metallic states across decades of conductance can be encoded in the size of ferroelectric nanodomains using electric field. © 2011 American Chemical Society

  12. Electrotunable nanoplasmonic liquid mirror

    Science.gov (United States)

    Montelongo, Yunuen; Sikdar, Debabrata; Ma, Ye; McIntosh, Alastair J. S.; Velleman, Leonora; Kucernak, Anthony R.; Edel, Joshua B.; Kornyshev, Alexei A.

    2017-11-01

    Recently, there has been a drive to design and develop fully tunable metamaterials for applications ranging from new classes of sensors to superlenses among others. Although advances have been made, tuning and modulating the optical properties in real time remains a challenge. We report on the first realization of a reversible electrotunable liquid mirror based on voltage-controlled self-assembly/disassembly of 16 nm plasmonic nanoparticles at the interface between two immiscible electrolyte solutions. We show that optical properties such as reflectivity and spectral position of the absorption band can be varied in situ within +/-0.5 V. This observed effect is in excellent agreement with theoretical calculations corresponding to the change in average interparticle spacing. This electrochemical fully tunable nanoplasmonic platform can be switched from a highly reflective `mirror' to a transmissive `window' and back again. This study opens a route towards realization of such platforms in future micro/nanoscale electrochemical cells, enabling the creation of tunable plasmonic metamaterials.

  13. Measurement of group velocity dispersion in a solid-core photonic crystal fiber filled with a nematic liquid crystal.

    Science.gov (United States)

    Wahle, Markus; Kitzerow, Heinz

    2014-08-15

    Liquid crystal-filled photonic crystal fibers (PCFs) are promising candidates for electrically tunable integrated photonic devices. In this Letter, we present group velocity measurements on such fibers. A large mode area PCF, LMA8, was infiltrated with the liquid crystal mixture, E7. The measurements were performed with an interferometric setup. The fiber exhibits several spectral transmission windows in the visible wavelength regime that originate from the bandgap guiding mechanism. The dispersion of these windows is very unusual compared to typical fibers. Our measurements show that it can change from -2500 ps km(-1) nm(-1) to +2500 ps km(-1) nm(-1) within a spectral range of only 15 nm. This leads to multiple zero dispersion wavelengths in the visible wavelength range.

  14. Fast axial scanning for 2-photon microscopy using liquid lens technology

    Science.gov (United States)

    Tehrani, Kayvan Forouhesh; Sun, Min Kyoung; Karumbaiah, Lohitash; Mortensen, Luke J.

    2017-02-01

    Scanning microscopy methods require movement of the focus in Z coordinates to produce an image of a 3-dimensional volume. In a typical imaging system, the optical setup is kept fixed and either the sample or the objective is translated with a mechanical stage driven by a stepper motor or a piezoelectric element. Mechanical Z scanning is precise, but its slow response and vulnerability to mechanical vibrations and stress make it disadvantageous to image dynamic, time-varying samples such as live cell structures. An alternative method less susceptible to these problems is to change the focal plane using conjugate optics. Deformable mirrors, acousto-optics, and electrically tunable lenses have been experimented with to achieve this goal and have attained very fast and precise Z-scanning without physically moving the sample. Here, we present the use of a liquid lens for fast axial scanning. Liquid lenses have a long functional life, high degree of phase shift, and low sensitivity to mechanical stress. They work on the principle of refraction at a liquid-liquid interface. At the boundary of a polar and an apolar liquid a spherical surface is formed whose curvature can be controlled by adjusting its relative wettability using electro-wetting. We characterize the effects of the lens on attainable Z displacement, beam spectral characteristics, and pulse duration as compared with mechanical scanning.

  15. Liquid Crystal-Reconfigurable Antenna Concepts for Space Applications at Microwave and Millimeter Waves

    Directory of Open Access Journals (Sweden)

    A. Gaebler

    2009-01-01

    Full Text Available Novel approaches of tunable devices for millimeter wave applications based on liquid crystal (LC are presented. In the first part of the paper, a novel concept of a tunable LC phase shifter realized in Low Temperature Cofired Ceramics technology is shown while the second part of the paper deals with a tunable high-gain antenna based on an LC tunable reflectarray. The reflectarray features continuously beam scanning in between ±25∘. Also first investigations on radiation hardness of LCs are carried out, indicating that LCs might be suitable for space applications.

  16. Active liquid-crystal deflector and lens with Fresnel structure

    Science.gov (United States)

    Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

    2017-02-01

    A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

  17. A Polarization Maintaining Filter based on a Liquid-Crystal-Photonic-Bandgap-Fiber

    DEFF Research Database (Denmark)

    Scolari, Lara; Olausson, Christina Bjarnal Thulin; Turchinovich, Dmitry

    2008-01-01

    A polarization maintaining filter based on a liquid-crystal-photonic-bandgap-fiber is demonstrated. Its polarization extinction ratio is 14 dB at 1550 nm. Its tunability is 150 nm.......A polarization maintaining filter based on a liquid-crystal-photonic-bandgap-fiber is demonstrated. Its polarization extinction ratio is 14 dB at 1550 nm. Its tunability is 150 nm....

  18. Nonlinear, tunable and active metamaterials

    CERN Document Server

    Lapine, Mikhail; Kivshar, Yuri

    2015-01-01

    Metamaterials, artificial electromagnetic media achieved by structuring on the subwave-length-scale were initially suggested for the negative index and superlensing. They became a paradigm for engineering electromagnetic space and controlling propagation of waves. The research agenda is now shifting on achieving tuneable, switchable, nonlinear and sensing functionalities. The time has come to talk about the emerging research field of metadevices employing active and tunable metamaterials with unique functionalities achieved by structuring of functional matter on the subwave-length scale. This book presents the first systematic and comprehensive summary of the reviews written by the pioneers and top-class experts in the field of metamaterials. It addresses many grand challenges of the cutting edge research for creating smaller and more efficient photonic structures and devices.

  19. Diode pumped tunable dye laser

    Science.gov (United States)

    Burdukova, O.; Gorbunkov, M.; Petukhov, V.; Semenov, M.

    2017-03-01

    A wavelength-tunable dye laser pumped by blue laser diodes (λ =445 nm) in a 200 ns pulsed mode has been developed. We used a 3-mirror cavity with transverse excitation and total internal reflection of laser beam in the active element. Tuning curves for 8 dyes in benzyl alcohol were measured in the range of 506-700 nm. Four dyes have their tuning range more than 60 nm, which is comparable to the tuning ranges of other dye lasers pumped by more expensive sources. The output energy obtained at the generation maximum of both DCM and coumarin 540A dyes was approximately 130 nJ while the pump energy was 2400 nJ.

  20. Thermo-responsive poly(ionic liquid) valves for microfluidic devices

    OpenAIRE

    Tudor, Alexandru; Saez, Janire; Florea, Larisa; Benito-Lopez, Fernando; Diamond, Dermot

    2016-01-01

    Poly(ionic liquid)s (PIL) are a class of ionic liquids that feature polymerizable groups in the cation, the anion or both. They retain most of the properties present in ionic liquids, including ionic conductivity, low vapour pressure and tunable physico-chemical properties. Several phosphonium ionic liquids have been shown to possess a lower critical solution temperature, making them suitable materials for the synthesis of temperature-responsive smart materials.1,2 Herein, we present the synt...

  1. Electro-Optic Tunable Laser Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will develop a compact, rugged, rapidly and widely tunable laser based on a quantum cascade diode laser at...

  2. Tunable Mechanical Filter for Longitudinal Vibrations

    National Research Council Canada - National Science Library

    Asiri, S

    2007-01-01

    This paper presents both theoretically and experimentally a new kind of vibration isolator called tunable mechanical filter which consists of four parallel hybrid periodic rods connected between two plates...

  3. Thermally tunable ferroelectric thin film photonic crystals.

    Energy Technology Data Exchange (ETDEWEB)

    Lin, P. T.; Wessels, B. W.; Imre, A.; Ocola, L. E.; Northwestern Univ.

    2008-01-01

    Thermally tunable PhCs are fabricated from ferroelectric thin films. Photonic band structure and temperature dependent diffraction are calculated by FDTD. 50% intensity modulation is demonstrated experimentally. This device has potential in active ultra-compact optical circuits.

  4. Tunable beam steering enabled by graphene metamaterials.

    Science.gov (United States)

    Orazbayev, B; Beruete, M; Khromova, I

    2016-04-18

    We demonstrate tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. The effective refractive index of such metamaterials can be manipulated by changing the chemical potential of each graphene layer. This can arbitrarily tailor the spatial distribution of the phase of the transmitted beam, providing mechanisms for active beam steering. Three different beam steerer (BS) designs are discussed: a graded-index (GRIN) graphene-based metamaterial block, an array of metallic waveguides filled with graphene-dielectric metamaterial and an array of planar waveguides created in a graphene-dielectric metamaterial block with a specific spatial profile of graphene sheets doping. The performances of the BSs are numerically analyzed, showing the tunability of the proposed designs for a wide range of output angles (up to approximately 70°). The proposed graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.

  5. Tunable Multifunction Filter Using Current Conveyor

    OpenAIRE

    Manish Kumar; Srivastava, M. C.; Umesh Kumar

    2010-01-01

    The paper presents a current tunable multifunction filter using current conveyor. The proposed circuit can be realized as on chip tunable low pass, high pass, band pass and elliptical notch filter. The circuit employs two current conveyors, one OTA, four resistors and two grounded capacitors, ideal for integration. It has only one output terminal and the number of input terminals may be used. Further, there is no requirement for component matching in the circuit. The resonance frequency ({\\om...

  6. A disorder-based strategy for tunable, broadband wave attenuation

    Science.gov (United States)

    Zhang, Weiting; Celli, Paolo; Cardella, Davide; Gonella, Stefano

    2017-04-01

    One of the most daunting limitations of phononic crystals and acoustic/elastic metamaterials is their passivity: a given configuration is bound to display its phononic properties only around its design point, i.e., working at some pre-determined operating conditions. In the past decade, this shortcoming has inspired the design of phononic media with tunable wave characteristics; noteworthy results have been obtained through a family of methodologies involving shunted piezoelectric elements. Shunting a piezoelectric element means connecting it to a passive electric circuit; tunability stems from the ability to modify the effective mechanical properties of the piezoelectric medium by modifying the circuit characteristics. One of the most popular shunting circuits is the resistor-inductor, which allows the patch-and-shunt system to behave as an electromechanical resonator. A common motif among the works employing shunted piezos for phononic control is periodicity: the patches are typically periodically placed in the domain and the circuits are identically tuned. The objective of this work is to demonstrate that the wave attenuation performance of structures with shunted piezoelectric patches can be improved by leveraging notions of organized disorder. Based on the idea of rainbow trapping broadband wave attenuation obtained by tuning an array of resonators at distinct neighboring frequencies we design and test an electromechanical waveguide structure capable of attenuating waves over broad frequency ranges. In order to emphasize the fact that periodicity is not a binding requirement when working with RL shunts (which induce locally resonant bandgaps), we report on the performance of random arrangements of patches. In an attempt to demonstrate the tunability attribute of our strategy, we take advantage of the reconfigurability of the circuits to show how a single waveguide can attenuate both waves and vibrations over different frequency ranges.

  7. Directed Self-Assembly of Colloidal Particles onto Nematic Liquid Crystalline Defects Engineered by Chemically Patterned Surfaces.

    Science.gov (United States)

    Li, Xiao; Armas-Pérez, Julio C; Hernández-Ortiz, Juan P; Arges, Christopher G; Liu, Xiaoying; Martínez-González, José A; Ocola, Leonidas E; Bishop, Camille; Xie, Helou; de Pablo, Juan J; Nealey, Paul F

    2017-06-27

    In exploiting topological defects of liquid crystals as the targeting sites for trapping colloidal objects, previous work has relied on topographic features with uniform anchoring to create defects, achieving limited density and spacing of particles. We report a generalizable strategy to create topological defects on chemically patterned surfaces to assemble particles in precisely defined locations with a tunable interparticle distance at nanoscale dimensions. Informed by experimental observations and numerical simulations that indicate that liquid crystals, confined between a homeotropic-anchoring surface and a surface with lithographically defined planar-anchoring stripes in a homeotropic-anchoring background, display splay-bend deformation, we successfully create pairs of defects and subsequently trap particles with controlled spacing by designing patterns of intersecting stripes aligned at 45° with homeotropic-anchoring gaps at the intersections. Application of electric fields allows for dynamic control of trapped particles. The tunability, responsiveness, and adaptability of this platform provide the opportunities for assembly of colloidal structures toward functional materials.

  8. Underwater tunable organ-pipe sound source.

    Science.gov (United States)

    Morozov, Andrey K; Webb, Douglas C

    2007-08-01

    A highly efficient frequency-controlled sound source based on a tunable high-Q underwater acoustic resonator is described. The required spectrum width was achieved by transmitting a linear frequency-modulated signal and simultaneously tuning the resonance frequency, keeping the sound source in resonance at the instantaneous frequency of the signal transmitted. Such sound sources have applications in ocean-acoustic tomography and deep-penetration seismic tomography. Mathematical analysis and numerical simulation show the Helmholtz resonator's ability for instant resonant frequency switching and quick adjustment of its resonant frequency to the instantaneous frequency signal. The concept of a quick frequency adjustment filter is considered. The discussion includes the simplest lumped resonant source as well as the complicated distributed system of a tunable organ pipe. A numerical model of the tunable organ pipe is shown to have a form similar to a transmission line segment. This provides a general form for the principal results, which can be applied to tunable resonators of a different physical nature. The numerical simulation shows that the "state-switched" concept also works in the high-Q tunable organ pipe, and the speed of frequency sweeping in a high-Q tunable organ pipe is analyzed. The simulation results were applied to a projector design for ocean-acoustic tomography.

  9. Conductive Polymer Porous Film with Tunable Wettability and Adhesion

    Directory of Open Access Journals (Sweden)

    Yuqi Teng

    2015-04-01

    Full Text Available A conductive polymer porous film with tunable wettability and adhesion was fabricated by the chloroform solution of poly(3-hexylthiophene (P3HT and [6,6]-phenyl-C61-butyricacid-methyl-ester (PCBM via the freeze drying method. The porous film could be obtained from the solution of 0.8 wt%, whose pore diameters ranged from 50 nm to 500 nm. The hydrophobic porous surface with a water contact angle (CA of 144.7° could be transferred into a hydrophilic surface with CA of 25° by applying a voltage. The water adhesive force on the porous film increased with the increase of the external voltage. The electro-controllable wettability and adhesion of the porous film have potential application in manipulating liquid collection and transportation.

  10. Multifunctional industrial combustion process monitoring with tunable diode lasers

    Science.gov (United States)

    Von Drasek, William A.; Charon, Olivier; Mulderink, Ken; Sonnenfroh, David M.; Allen, Mark G.

    2001-02-01

    12 To address the inherent issues with extractive sampling, Air Liquide and PSI are collaborating on the development of an in-situ multi-functional near-IR tunable diode laser system. The system is specifically targeted for application in harsh combustion environments with flue gas temperatures > 1600 degree(s)C and high particle densities. The multiplexing capability of the diode laser system allows near simultaneous detection of CO, O2, and H2O. These are essential species in characterizing the combustion state of the process, i.e., fuel-rich or fuel-lean, and the flue gas temperature. Sensor development and testing are conducted on a 700 kW oxy-fuel pilot furnace to evaluate the performance under simulated industrial conditions. Here we present pilot test results for dynamic stoichiometry changes, effect of particle entrainment, and air infiltration monitoring.

  11. Enabling tunable micromechanical bandpass filters through phase-change materials

    Science.gov (United States)

    Cao, Yunqi; Torres, David; Wang, Tongyu; Tan, Xiaobo; Sepúlveda, Nelson

    2017-08-01

    Vanadium dioxide (VO2), one of the most promising phase-change smart materials, has shown strong frequency tuning capabilities in MEMS resonators. In this paper, we demonstrate the potential use of VO2-based MEMS devices as second-order kilohertz (kHz) bandpass filters with tunable band selectivity and adjustable bandwidth (BW). Two identical on-chip micro resonators are actuated using mechanical excitation and measured using optical detection. One of the resonators is not actuated while the other is tuned by applying electric currents across an integrated resistive heater, which induces the phase transition of the VO2, and consequently a large stress to the mechanical structure. The responses of both MEMS resonators are combined, resulting in a resonant peak of tunable BW controlled by the input current. The BW can be extended to 2.62 times by using two bridges or 2.39 times by implementing one pair of cantilevers. The results for both devices are discussed.

  12. Self-orientation effect of liquid crystals on holographic polymer-dispersed liquid crystal and distributed feedback lasers

    Science.gov (United States)

    Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Zhao, Haifeng; Cao, Zhaoliang; Xuan, Li

    2017-07-01

    The average orientation of a liquid crystal (LC) director to the grating formation, morphology, and switching properties of a holographic polymer-dispersed liquid crystal (HPDLC) grating was systematically investigated in this study. The grating possessed high diffraction efficiency and low scattering with the LC director being parallel to the grating vector. The scanning electron microscope confirmed the well-defined morphology with the LC director being parallel to the grating vector. The grating was easily switched when the LC director was perpendicular to the grating vector. Moreover, polarization excitation was performed to investigate the polarization dependence behavior of the HPDLC-distributed feedback (DFB) laser. The results confirmed that the HPDLC grating is suitable as a laser oscillation when the LC director is parallel to the grating vector. Finally, the tuning range was obtained for the HPDLC DFB laser by applying an external electric field. The tunability, ease of fabrication, and mass production make the HPDLC DFB lasers suitable as smart laser sources for spectroscopy and communication.

  13. Ionic liquids and derived materials for lithium and sodium batteries.

    Science.gov (United States)

    Yang, Qiwei; Zhang, Zhaoqiang; Sun, Xiao-Guang; Hu, Yong-Sheng; Xing, Huabin; Dai, Sheng

    2018-02-02

    The ever-growing demand for advanced energy storage devices in portable electronics, electric vehicles and large scale power grids has triggered intensive research efforts over the past decade on lithium and sodium batteries. The key to improve their electrochemical performance and enhance the service safety lies in the development of advanced electrode, electrolyte, and auxiliary materials. Ionic liquids (ILs) are liquids consisting entirely of ions near room temperature, and are characterized by many unique properties such as ultralow volatility, high ionic conductivity, good thermal stability, low flammability, a wide electrochemical window, and tunable polarity and basicity/acidity. These properties create the possibilities of designing batteries with excellent safety, high energy/power density and long-term stability, and also provide better ways to synthesize known materials. IL-derived materials, such as poly(ionic liquids), ionogels and IL-tethered nanoparticles, retain most of the characteristics of ILs while being endowed with other favourable features, and thus they have received a great deal of attention as well. This review provides a comprehensive review of the various applications of ILs and derived materials in lithium and sodium batteries including Li/Na-ion, dual-ion, Li/Na-S and Li/Na-air (O2) batteries, with a particular emphasis on recent advances in the literature. Their unique characteristics enable them to serve as advanced resources, medium, or ingredient for almost all the components of batteries, including electrodes, liquid electrolytes, solid electrolytes, artificial solid-electrolyte interphases, and current collectors. Some thoughts on the emerging challenges and opportunities are also presented in this review for further development.

  14. Inorganic nanosheet liquid crystals and their applications (Conference Presentation)

    Science.gov (United States)

    Miyamoto, Nobuyoshi

    2016-09-01

    Liquid crystal (LC) phase of inorganic nanosheets is fascinating system in the field of condensed matter physics and for potential applications in many fields. In this lecture, I present my research on the LC nanosheet colloids derived from clay minerals, layered niobates, layered titnates, and layered perovskites. Structural analyses by small angle X-ray scattering and confocal laser scanning microscopy reveals not only meso-scale lamellar or nematic structures in the LC phase but also fractal-like porous structures. In that structure, the nanosheets show translational and rotational Brownian motions as revealed by fast-scanning confocal microscopy. The structure is tunable by many factors such as nanosheet concentration, nanosheet lateral size, salt concentration, solvent, counter cations, and charge density of the nanosheets. Some optimized systems show variable structural colors which will be useful for color materials and sensor devices. Under ac-electric field, the orientation of the nanosheets and LC domain is easily controllable; the electric field response is applicable for fabrication of electro-optic devices and formation of anisotropic composite materials. Among many future applications, inorganic nanosheet/ polymer composites with precisely controllable hierarchical structure are fascinating. We synthesized a cm-scale mono-domain gel of exfoliated LC clay/polymer composite. The gel is printable with a dye and the colored part shows photo-induced anomalous deformation behavior, which will be applicable as chemical actuators.

  15. Characteristics of mechanically tunable superconductive resonators

    Energy Technology Data Exchange (ETDEWEB)

    Mine, Shigenobu; Terakago, Masafumi; Sakatani, Tomotaka; Hontsu, Shigeki; Nishikawa, Hiroaki [Department of Electronic System and Information Engineering, Faculty of Biology-Oriented Science and Technology, Kinki University, Naga-gun, Wakayama (Japan); Fujimaki, Akira [Department of Quantum Engineering, Nagoya University, Chikusa-ku, Nagoya (Japan); Nakamori, Masaya [Department of Electrical and Information Engineering, Kinki University Technical College, Kumano, Mie (Japan); Tabata, Hitoshi; Kawai, Tomoji [Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka (Japan)

    2002-04-01

    In order to realize superconductive microwave devices with large tuning characteristics, we have studied a mechanically tunable superconductive resonator beneath a dielectric and/or magnetic floating plate (FP) as a first step. The resonator consists of a half-wavelength coplanar waveguide (CPW). The principle of the mechanically tunable method is that variations of the effective permittivity and/or the effective permeability for the microwave waveguide line can be obtained by changing the distance between the resonator and the FP. In computer simulations of electromagnetic fields for the mechanically tunable half-wavelength CPW resonator, we have obtained a large shift of the resonant frequency with a band of 1.75 GHz to 7 GHz (tunability is approximately 25%) using the (La{sub 0.3}Sr{sub 0.7})(Al{sub 0.65}Ta{sub 0.35})O{sub 3} (LSAT) single crystal (dielectric constant ({epsilon}{sub r})=22.8, loss tangent (tan{delta})=1.7x10{sup -4}) as the FP. Based on the results, we have performed an experiment using a half-wavelength CPW resonator made from YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin film and the LSAT FP. The result shows a drastic resonant frequency shift of approximately 1.36 GHz (tunability is approximately 20%) when the LSAT FP is moved, using an electromagnetic actuator. In this experiment, it is also noted that the insertion loss is quite low, less than 0.8 dB, compared to previous reports for various tunable filters. Moreover, we have also measured the tuning characteristics with a TiO{sub 2} single crystal ({epsilon}{sub r}=85.4, tan{delta}=2.5x10{sup -4}) as the FP. As a result, we have obtained quite large tuning characteristics of approximately 2 GHz (tunability is approximately 28%). (author)

  16. Tunable Micro- and Nanomechanical Resonators

    Directory of Open Access Journals (Sweden)

    Wen-Ming Zhang

    2015-10-01

    Full Text Available Advances in micro- and nanofabrication technologies have enabled the development of novel micro- and nanomechanical resonators which have attracted significant attention due to their fascinating physical properties and growing potential applications. In this review, we have presented a brief overview of the resonance behavior and frequency tuning principles by varying either the mass or the stiffness of resonators. The progress in micro- and nanomechanical resonators using the tuning electrode, tuning fork, and suspended channel structures and made of graphene have been reviewed. We have also highlighted some major influencing factors such as large-amplitude effect, surface effect and fluid effect on the performances of resonators. More specifically, we have addressed the effects of axial stress/strain, residual surface stress and adsorption-induced surface stress on the sensing and detection applications and discussed the current challenges. We have significantly focused on the active and passive frequency tuning methods and techniques for micro- and nanomechanical resonator applications. On one hand, we have comprehensively evaluated the advantages and disadvantages of each strategy, including active methods such as electrothermal, electrostatic, piezoelectrical, dielectric, magnetomotive, photothermal, mode-coupling as well as tension-based tuning mechanisms, and passive techniques such as post-fabrication and post-packaging tuning processes. On the other hand, the tuning capability and challenges to integrate reliable and customizable frequency tuning methods have been addressed. We have additionally concluded with a discussion of important future directions for further tunable micro- and nanomechanical resonators.

  17. Tunable VO{sub 2}/Au hyperbolic metamaterial

    Energy Technology Data Exchange (ETDEWEB)

    Prayakarao, S.; Noginov, M. A., E-mail: mnoginov@nsu.edu [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Mendoza, B.; Devine, A. [Summer Research Program, Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850 (United States); Kyaw, C. [Summer Research Program, Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Dover, R. B. van [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850 (United States); Liberman, V. [MIT LINCOLN Laboratory, 244 Wood Street, Lexington, Massachusetts 02420 (United States)

    2016-08-08

    Vanadium dioxide (VO{sub 2}) is known to have a semiconductor-to-metal phase transition at ∼68 °C. Therefore, it can be used as a tunable component of an active metamaterial. The lamellar metamaterial studied in this work is composed of subwavelength VO{sub 2} and Au layers and is designed to undergo a temperature controlled transition from the optical hyperbolic phase to the metallic phase. VO{sub 2} films and VO{sub 2}/Au lamellar metamaterial stacks have been fabricated and studied in electrical conductivity and optical (transmission and reflection) experiments. The observed temperature-dependent changes in the reflection and transmission spectra of the metamaterials and VO{sub 2} thin films are in a good qualitative agreement with theoretical predictions. The demonstrated optical hyperbolic-to-metallic phase transition is a unique physical phenomenon with the potential to enable advanced control of light-matter interactions.

  18. Tunable dielectric properties of ferrite-dielectric based metamaterial.

    Directory of Open Access Journals (Sweden)

    K Bi

    Full Text Available A ferrite-dielectric metamaterial composed of dielectric and ferrite cuboids has been investigated by experiments and simulations. By interacting with the electromagnetic wave, the Mie resonance can take place in the dielectric cuboids and the ferromagnetic precession will appear in the ferrite cuboids. The magnetic field distributions show the electric Mie resonance of the dielectric cuboids can be influenced by the ferromagnetic precession of ferrite cuboids when a certain magnetic field is applied. The effective permittivity of the metamaterial can be tuned by modifying the applied magnetic field. A good agreement between experimental and simulated results is demonstrated, which confirms that these metamaterials can be used for tunable microwave devices.

  19. Gate-Tunable Spatial Modulation of Localized Plasmon Resonances.

    Science.gov (United States)

    Arcangeli, Andrea; Rossella, Francesco; Tomadin, Andrea; Xu, Jihua; Ercolani, Daniele; Sorba, Lucia; Beltram, Fabio; Tredicucci, Alessandro; Polini, Marco; Roddaro, Stefano

    2016-09-14

    We demonstrate localization and field-effect spatial control of the plasmon resonance in semiconductor nanostructures, using scattering-type scanning near-field optical microscopy in the mid-infrared region. We adopt InAs nanowires embedding a graded doping profile to modulate the free carrier density along the axial direction. Our near-field measurements have a spatial resolution of 20 nm and demonstrate the presence of a local resonant feature whose position can be controlled by a back-gate bias voltage. In the present implementation, field-effect induces a modulation of the free carrier density profile yielding a spatial shift of the plasmon resonance of the order of 100 nm. We discuss the relevance of our electrically tunable nanoplasmonic architectures in view of innovative optoelectronic devices concepts.

  20. Tunable Multilayer Graphene Metamaterials for Terahertz/Infrared Waveguide Modulators

    DEFF Research Database (Denmark)

    Khromova, Irina; Andryieuski, Andrei; Lavrinenko, Andrei

    of radiation. Various approaches have been proposed for THz/IR amplitude, phase, spatial and temporal profile modulation, including the employment of metamaterials [1] and, recently, one-atom-thick graphene [2]. Most of the proposed modulators, including graphene-based ones, are developed for free...... regimes of multilayer graphene-dielectric artificial metamaterials. The interplay between interband and intraband transitions in graphene allows converting the structure into a transparent and/or electromagnetically dense artificial medium. The gate voltage can be used to electrically control...... the concentration of carriers in the graphene sheets and, thus, efficiently change the dispersion of the whole structure. Placed inside a hollow waveguide, a multilayer graphene/dielectric metamaterial provides high-speed modulation and tunable bandpass filtering. The absence of scattered radiation enables dense...