WorldWideScience

Sample records for broadband pulsar-like polarization

  1. Terahertz broadband polarization converter based on metamaterials

    Science.gov (United States)

    Li, Yonghua; Zhao, Guozhong

    2018-01-01

    Based on the metamaterial composed of symmetrical split resonant ring, a broadband reflective terahertz polarization converter is proposed. The numerical simulation shows that it can rotate the polarization direction of linear polarized wave 90° in the range of 0.7-1.8THz and the polarization conversion ratio is over 90%. The reflection coefficient of the two electric field components in the diagonal direction is the same and the phase difference is 180° ,which leads to the cross-polarization rotation.In order to further study the physical mechanism of high polarization conversion, we analyze the surface current distribution of the resonant ring. The polarization converter has potential applications in terahertz wave plate and metamaterial antenna design.

  2. Design of broadband single polarized antenna

    Science.gov (United States)

    Shin, Phoo Kho; Aziz, Mohamad Zoinol Abidin Abd.; Ahmad, Badrul Hisham; Ramli, Mohamad Hafize Bin; Fauzi, Noor Azamiah Md; Malek, Mohd Fareq Abd

    2015-05-01

    In practical wireless communication application, bandwidth enhancement becomes one of the major design considerations. At the same time, circular polarized (CP) antenna received much attention for the applications of modern wireless communication system when compared to linear polarized (LP) antenna. This is because CP antenna can reduce the multipath effect. Hence, broadband antenna with operating frequency at 2.4GHz for WLAN application is proposed. The proposed antenna is done by using L-probe amendment with rectangular patch. The rectangular patch and copper ground plane is separated with 10mm air gap. This approach is used to enhance the bandwidth and the gain of the proposed antenna. The bandwidth of the designed antenna is more than 200MHz which meet broadband application. The return loss for the antenna is below -10dB to achieved 90% matching efficiency. The position of L-probe feed is altered in order to obtained different polarizations. The broadband antenna had been designed and simulated by using Computer Simulation Technology (CST) software. In this paper, the comparison for single polarized antenna with the design of non-inverted patch and inverted patch is discussed. The characteristics of the S-parameter, axial ratio, gain, surface current for each designed antenna are analyzed.

  3. Efficient composite broadband polarization retarders and polarization filters

    Science.gov (United States)

    Dimova, E.; Ivanov, S. S.; Popkirov, G.; Vitanov, N. V.

    2014-12-01

    A new type of broadband polarization half-wave retarder and narrowband polarization filters are described and experimentally tested. Both, the retarders and the filters are designed as composite stacks of standard optical half-wave plates, each of them twisted at specific angles. The theoretical background of the proposed optical devices was obtained by analogy with the method of composite pulses, known from the nuclear and quantum physics. We show that combining two composite filters built from different numbers and types of waveplates, the transmission spectrum is reduced from about 700 nm to about 10 nm width.We experimentally demonstrate that this method can be applied to different types of waveplates (broadband, zero-order, multiple order, etc.).

  4. Freely tunable broadband polarization rotator for terahertz waves.

    Science.gov (United States)

    Fan, Ren-Hao; Zhou, Yu; Ren, Xiao-Ping; Peng, Ru-Wen; Jiang, Shang-Chi; Xu, Di-Hu; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    2015-02-18

    A freely tunable polarization rotator for broadband terahertz waves is demonstrated using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized terahertz wave to any desired direction with nearly perfect conversion efficiency. This low-cost, high-efficiency, and freely tunable device has potential applications as material analysis, wireless communication, and THz imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Metallic stereostructured layer: An approach for broadband polarization state manipulation

    International Nuclear Information System (INIS)

    Xiong, Xiang; Hu, Yuan-Sheng; Jiang, Shang-Chi; Hu, Yu-Hui; Fan, Ren-Hao; Ma, Guo-Bin; Shu, Da-Jun; Peng, Ru-Wen; Wang, Mu

    2014-01-01

    In this letter, we report a full-metallic broadband wave plate assembled by standing metallic L-shaped stereostructures (LSSs). We show that with an array of LSSs, high polarization conversion ratio is achieved within a broad frequency band. Moreover, by rotating the orientation of the array of LSSs, the electric components of the reflection beam in two orthogonal directions and their phase difference can be independently tuned. In this way, all the polarization states on the Poincaré sphere can be realized. As examples, the functionalities of a quarter wave plate and a half wave plate are experimentally demonstrated with both reflection spectra and focal-plane-array imaging. Our designing provides a unique approach in realizing the broadband wave plate to manipulate the polarization state of light

  6. Broad-Band Analysis of Polar Motion Excitations

    Science.gov (United States)

    Chen, J.

    2016-12-01

    Earth rotational changes, i.e. polar motion and length-of-day (LOD), are driven by two types of geophysical excitations: 1) mass redistribution within the Earth system, and 2) angular momentum exchange between the solid Earth (more precisely the crust) and other components of the Earth system. Accurate quantification of Earth rotational excitations has been difficult, due to the lack of global-scale observations of mass redistribution and angular momentum exchange. The over 14-years time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) have provided a unique means for quantifying Earth rotational excitations from mass redistribution in different components of the climate system. Comparisons between observed Earth rotational changes and geophysical excitations estimated from GRACE, satellite laser ranging (SLR) and climate models show that GRACE-derived excitations agree remarkably well with polar motion observations over a broad-band of frequencies. GRACE estimates also suggest that accelerated polar region ice melting in recent years and corresponding sea level rise have played an important role in driving long-term polar motion as well. With several estimates of polar motion excitations, it is possible to estimate broad-band noise variance and noise power spectra in each, given reasonable assumptions about noise independence. Results based on GRACE CSR RL05 solutions clearly outperform other estimates with the lowest noise levels over a broad band of frequencies.

  7. Polarization-independent broadband meta-holograms via polarization-dependent nanoholes.

    Science.gov (United States)

    Zhang, Xiaohu; Li, Xiong; Jin, Jinjin; Pu, Mingbo; Ma, Xiaoliang; Luo, Jun; Guo, Yinghui; Wang, Changtao; Luo, Xiangang

    2018-05-17

    Composed of ultrathin metal or dielectric nanostructures, metasurfaces can manipulate the phase, amplitude and polarization of electromagnetic waves at a subwavelength scale, which is promising for flat optical devices. In general, metasurfaces composed of space-variant anisotropic units are sensitive to the incident polarization due to the inherent polarization dependent geometric phase. Here, we implement polarization-independent broadband metasurface holograms constructed by polarization-dependent anisotropic elliptical nanoholes by elaborate design of complex amplitude holograms. The fabricated meta-hologram exhibits a polarization insensitive feature with an acceptable image quality. We verify the feasibility of the design algorithm for three-dimensional (3D) meta-holograms with simulation and the feasibility for two-dimensional (2D) meta-holograms is experimentally demonstrated at a broadband wavelength range from 405 nm to 632.8 nm. The effective polarization-independent broadband complex wavefront control with anisotropic elliptical nanoholes proposed in this paper greatly promotes the practical applications of the metasurface in technologies associated with wavefront manipulation, such as flat lens, colorful holographic displays and optical storage.

  8. Broadband and polarization reflectors in the lookdown, Selene vomer.

    Science.gov (United States)

    Zhao, Shulei; Brady, Parrish Clawson; Gao, Meng; Etheredge, Robert Ian; Kattawar, George W; Cummings, Molly E

    2015-03-06

    Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Ultra-broadband carpet cloak for transverse-electric polarization

    International Nuclear Information System (INIS)

    Deng, Ye; Xu, Su; Zhang, Runren; Zheng, Bin; Chen, Hongsheng; Chen, Hua; Yu, Faxin; Gao, Fei; Zhang, Baile

    2016-01-01

    Magnetism is a necessity in constructing macroscopic metamaterial invisibility cloaks that are theoretically designed by transformation optics, but will generally limit the cloaking bandwidth to an impractically narrow range. To meet the broad bandwidth demand, magnetism has been fully abandoned in previous demonstrations of macroscopic carpet cloaking, whose approach, however, cannot apply to a transverse-electric (TE) polarization. To fill this gap, here we experimentally demonstrate an ultra-broadband magnetic carpet cloak for the TE polarization. The cloak is made of non-resonant closed-ring metamaterials with little dispersion and the cloaking performance is confirmed with both time-domain simulation and frequency scanning measurement over a broad bandwidth corresponding to a pulse signal illumination. (paper)

  10. Ultra-broadband carpet cloak for transverse-electric polarization

    Science.gov (United States)

    Deng, Ye; Xu, Su; Zhang, Runren; Zheng, Bin; Chen, Hua; Gao, Fei; Yu, Faxin; Zhang, Baile; Chen, Hongsheng

    2016-04-01

    Magnetism is a necessity in constructing macroscopic metamaterial invisibility cloaks that are theoretically designed by transformation optics, but will generally limit the cloaking bandwidth to an impractically narrow range. To meet the broad bandwidth demand, magnetism has been fully abandoned in previous demonstrations of macroscopic carpet cloaking, whose approach, however, cannot apply to a transverse-electric (TE) polarization. To fill this gap, here we experimentally demonstrate an ultra-broadband magnetic carpet cloak for the TE polarization. The cloak is made of non-resonant closed-ring metamaterials with little dispersion and the cloaking performance is confirmed with both time-domain simulation and frequency scanning measurement over a broad bandwidth corresponding to a pulse signal illumination.

  11. Ultracompact and broadband polarization beam splitter based on polarization-dependent critical guiding condition.

    Science.gov (United States)

    Ying, Zhoufeng; Wang, Guanghui; Zhang, Xuping; Ho, Ho-pui; Huang, Ying

    2015-05-01

    An ultracompact and broadband polarization beam splitter (PBS) based on the polarization-dependent critical guiding condition of an asymmetrical directional coupler is proposed. The device consists of a pair of silicon waveguides with different height and width. Due to the different cutoff conditions for the TE and TM polarization modes, it is possible to have the TM mode guided in one waveguide while the TE mode is supported in both. Therefore, only the phase-matching condition for the cross-coupling of the TE mode needs to be considered. This approach not only simplifies the design procedures but also significantly improves device performance with smaller total length and larger bandwidth. Finally, regardless of the contribution of S-bend waveguides, our proposed PBS has a coupling region as short as 0.2 μm, which is the shortest reported until now. The simulation result shows that the extinction ratios for the TE and TM polarization are 13.5 and 16.6 dB at their respective output ports, and their insertion losses are 0.29 and 0.13 dB, respectively. Numerical simulations also show that the device offers a very large bandwidth (∼140  nm) with large extinction ratio (>10  dB) and low insertion loss (<1  dB).

  12. A photo-excited broadband to dual-band tunable terahertz prefect metamaterial polarization converter

    Science.gov (United States)

    Zhu, Jianfeng; Yang, Yang; Li, Shufang

    2018-04-01

    A new and simple design of photo-excited broadband to dual-band tunable terahertz (THz) metamaterial cross polarization converter is proposed in this paper. The tunable converter is a sandwich structure with the center-cut cross-shaped metallic patterned structure as a resonator, the middle dielectric layer as a spacer and the bottom metallic film as the ground. The conductivity of the photoconductive semiconductor (Silicon) filled in the gap of the cross-shaped metallic resonator can be tuned by the incident pump power, leading to an easy modulation of the electromagnetic response of the proposed converter. The results show that the proposed cross-polarization converter can be tuned from a broadband with polarization conversion ratio (PCR) beyond 95% (1.86-2.94 THz) to dual frequency bands (fl = 1 . 46 THz &fh = 2 . 9 THz). The conversion peaks can reach 99.9% for the broadband and, 99.5% (fl) and 99.7% (fh) for the dual-band, respectively. Most importantly, numerical simulations demonstrate that the broadband/dual-band polarization conversion mechanism of the converter originates from the localized surface plasmon modes, which make the design simple and different from previous designs. With these good features, the proposed broadband to dual-band tunable polarization converter is expected to be used in widespread applications.

  13. A Design of 45-Degree Dual-Polarization Broadband Plane Station Antenna

    Directory of Open Access Journals (Sweden)

    Jianming Zhou

    2015-01-01

    Full Text Available A new broadband planar dual-polarization base station antenna is proposed, the antenna consists of two broadband plane coplanar base station antenna units, and so it has features of plane antenna. Two broadband plane station antenna units can, respectively, form double polarization in the direction. We analyzed the relative positions between the two antenna units and their effects on the performances of the antenna, especially for the influence of isolation. Broadband antenna has the characteristics of the broadband station antenna, and bandwidth is also guaranteed. The measured results show that the antenna can obtain 45% relative bandwidth, and 30 dB isolation degree also can be got, and the radiation performance is also good. Measurement results confirmed that the antenna gain can be guaranteed among 48% relative bandwidth, 15 dB of gain is got among bandwidth of 1.69–2.78 GHz, the isolation degree of different polarization method can reach 30 dB, and the measurement gain of two polarization methods of antenna both can reach 8.5 dBi.

  14. Realizing Broadband and Invertible Linear-to-circular Polarization Converter with Ultrathin Single-layer Metasurface

    Science.gov (United States)

    Li, Zhancheng; Liu, Wenwei; Cheng, Hua; Chen, Shuqi; Tian, Jianguo

    2015-01-01

    The arbitrary control of the polarization states of light has attracted the interest of the scientific community because of the wide range of modern optical applications that such control can afford. However, conventional polarization control setups are bulky and very often operate only within a narrow wavelength range, thereby resisting optical system miniaturization and integration. Here, we present the basic theory, simulated demonstration, and in-depth analysis of a high-performance broadband and invertible linear-to-circular (LTC) polarization converter composed of a single-layer gold nanorod array with a total thickness of ~λ/70 for the near-infrared regime. This setup can transform a circularly polarized wave into a linearly polarized one or a linearly polarized wave with a wavelength-dependent electric field polarization angle into a circularly polarized one in the transmission mode. The broadband and invertible LTC polarization conversion can be attributed to the tailoring of the light interference at the subwavelength scale via the induction of the anisotropic optical resonance mode. This ultrathin single-layer metasurface relaxes the high-precision requirements of the structure parameters in general metasurfaces while retaining the polarization conversion performance. Our findings open up intriguing possibilities towards the realization of novel integrated metasurface-based photonics devices for polarization manipulation, modulation, and phase retardation. PMID:26667360

  15. Broadband asymmetric transmission of linearly polarized electromagnetic waves based on chiral metamaterial

    Science.gov (United States)

    Stephen, Lincy; Yogesh, N.; Subramanian, V.

    2018-01-01

    The giant optical activity of chiral metamaterials (CMMs) holds great potential for tailoring the polarization state of an electromagnetic (EM) wave. In controlling the polarization state, the aspect of asymmetric transmission (AT), where a medium allows the EM radiation to pass through in one direction while restricting it in the opposite direction, adds additional degrees of freedom such as one-way channelling functionality. In this work, a CMM formed by a pair of mutually twisted slanted complementary metal strips is realized for broadband AT accompanied with cross-polarization (CP) conversion for linearly polarized EM waves. Numerically, the proposed ultra-thin (˜λ/42) CMM shows broadband AT from 8.58 GHz to 9.73 GHz (bandwidth of 1.15 GHz) accompanied with CP transmission magnitude greater than 0.9. The transmission and reflection spectra reveal the origin of the asymmetric transmission as the direction sensitive cross polarization conversion and anisotropic electric coupling occurring in the structure which is then elaborated with the surface current analysis and electric field distribution within the structure. An experiment is carried out to verify the broadband AT based CP conversion of the proposed CMM at microwave frequencies, and a reliable agreement between numerical and experimental results is obtained. Being ultra-thin, the reported broadband AT based CP conversion of the proposed CMM is useful for controlling radiation patterns in non-reciprocal EM devices and communication networks.

  16. 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....

  17. Broad-band linear polarization and magnetic intensification in rotating magnetic stars

    International Nuclear Information System (INIS)

    Degl'Innocenti, M.L.; Calamai, G.; Degl'Innocenti, E.L.; Patriarchi, P.

    1981-01-01

    Magnetic intensification is proposed as a mechanism to explain the general features of the variable broad-band linear polarization emerging from rotating magnetic stars. This mechanism is studied in detail, and some efforts are made to investigate the wide variety of polarization diagrams that can result from it. Theoretical results are compared with direct observations of the variable magnetic star 53 Cam to determine its geometric and magnetic configuration

  18. Silicon-on-insulator-based polarization-independent 1×3 broadband beam splitter with adiabatic coupling

    Science.gov (United States)

    Gong, Yuanhao; Liu, Lei; Chang, Limin; Li, Zhiyong; Tan, Manqing; Yu, Yude

    2017-10-01

    We propose and numerically simulate a polarization-independent 1×3 broadband beam splitter based on silicon-on-insulator (SOI) technology with adiabatic coupling. The designed structure is simulated by beam-propagation-method (BPM) and gets simulated transmission uniformity of three outputs better than 0.3dB for TE-polarization and 0.8dB for TM-polarization in a broadband of 180nm.

  19. Broadband polarization-independent and low-profile optically transparent metamaterial absorber

    Science.gov (United States)

    Li, Long; Xi, Rui; Liu, Haixia; Lv, Zhiyong

    2018-05-01

    A transparent metamaterial absorber with simultaneously high optical transparency and broadband microwave absorption is presented in this paper. Consisting of a two-layer soda-lime glass substrate and three-layer patch-shaped indium tin oxide (ITO) films, the proposed absorber has advantages of broadband absorption with an absorptivity higher than 85% in the range from 6.1 to 22.1 GHz, good polarization insensitiveness, a high transparency, a low profile, and wide-incident-angle stability. A prototype of the proposed absorber is fabricated and experimentally measured to demonstrate its excellent performance. The measured results agree well with the theoretical design and numerical simulations.

  20. Broadband photonic crystal fiber coupler with polarization selection of coupling ratio

    Science.gov (United States)

    Jaroszewicz, Leszek R.; Stasiewicz, Karol A.; Marć, Paweł; Szymański, Michał

    2010-09-01

    In the paper a new broadband photonic crystal fiber coupler is presented. The proper application of the biconical taper technology has been used for manufacturing the coupler without air holes collapse in LMA10 fiber (NKT Photonics Crystal). This coupler, operates in the weakly coupling condition, protects coupling operation in range from 900 nm to 1700 nm. The coupling ratio between output arms is depending on wavelength and can be tuning by selection the proper input state of polarization. It gives opportunity to use the broadband crystal fiber coupler in many applications in which it is necessary to tune a coupling between output arms during the measurement.

  1. Broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface

    Science.gov (United States)

    Mao, Chenyang; Yang, Yang; He, Xiaoxiang; Zheng, Jingming; Zhou, Chun

    2017-12-01

    In this paper, a broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface is proposed. The proposed metasurface can effectively convert linear-polarized (TE/TM) incident wave into the reflected wave with three different polarizations within the frequency bands of 5.5-22.75 GHz. Based on the electric and magnetic resonant features of the double-L-shaped structure, the proposed metasurface can convert linearly polarized waves into cross-polarized waves at three resonant frequency bands. Furthermore, the incident linearly polarized waves can be effectively converted into left/right handed circular-polarized (LHCP and RHCP) waves at other four non-resonance frequency bands. Thus, the proposed metasurface can be regarded as a seven-band multi-polarization converter. The prototype of the proposed polarization converter is analyzed and measured. Both simulated and measured results show the 3-dB axis ratio bandwidth of circular polarization bands and the high polarization conversion efficiency of cross-polarization bands when the incident wave changes from 0° to 30° at both TE and TM modes.

  2. Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes

    International Nuclear Information System (INIS)

    Dong Guo-Xiang; Xia Song; Li Wei; Zhang An-Xue; Xu Zhuo; Wei Xiao-Yong; Shi Hong-Yu

    2016-01-01

    In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency, covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%. At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave. (paper)

  3. Random Combinatorial Gradient Metasurface for Broadband, Wide-Angle and Polarization-Independent Diffusion Scattering.

    Science.gov (United States)

    Zhuang, Yaqiang; Wang, Guangming; Liang, Jiangang; Cai, Tong; Tang, Xiao-Lan; Guo, Tongfeng; Zhang, Qingfeng

    2017-11-29

    This paper proposes an easy, efficient strategy for designing broadband, wide-angle and polarization-independent diffusion metasurface for radar cross section (RCS) reduction. A dual-resonance unit cell, composed of a cross wire and cross loop (CWCL), is employed to enhance the phase bandwidth covering the 2π range. Both oblique-gradient and horizontal-gradient phase supercells are designed for illustration. The numerical results agree well with the theoretical ones. To significantly reduce backward scattering, the random combinatorial gradient metasurface (RCGM) is subsequently constructed by collecting eight supercells with randomly distributed gradient directions. The proposed metasurface features an enhanced specular RCS reduction performance and less design complexity compared to other candidates. Both simulated and measured results show that the proposed RCGM can significantly suppress RCS and exhibits broadband, wide-angle and polarization independence features.

  4. Broadband working-waveband-tunable polarization converter based on anisotropic metasurface

    Science.gov (United States)

    Lin, Yu; Wang, Lei; Gao, Jun; Lu, Yichao; Jiang, Suhua; Zeng, Wei

    2017-03-01

    We experimentally and theoretically demonstrate an ultrathin, broadband, and highly efficient metamaterial-based polarization converter with a metasurface/insulator/metal (MIM) configuration. In such a system, the resonance undergoes a transition from a vertical Fabry-Pérot type to a transverse type as the spacer thickness decreases. By changing the spacer thickness from 1 to 15 mm, the working waveband of this device could be tuned from 10.9-12.9 to 6-8 GHz without compromising the polarization conversion efficiency. Equivalent circuit theory and the transfer matrix method are used for demonstrating the physical mechanism of our device.

  5. Broadband Polarization-Insensitive Wavelength Conversion Based on Non-Degenerate Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2012-01-01

    We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements....

  6. Broadband non-polarizing beam splitter based on guided mode resonance effect

    International Nuclear Information System (INIS)

    Ma Jian-Yong; Xu Cheng; Qiang Ying-Huai; Zhu Ya-Bo

    2011-01-01

    A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that this double layer SOI structure can provide ∼50/50 beam ratio with the maximum divergences between reflection and transmission being less than 8% over the spectrum of 1.4 μm∼1.7 μm and 1% in the telecommunication band for both TE and TM polarizations. The physical basis of this broadband non-polarizing property is on the simultaneous excitation of the TE and TM strong modulation waveguide modes near the designed spectrum band. Meanwhile, the electric field distributions for both TE and TM polarizations verify the resonant origin of spectrum in the periodic SOI structure. Furthermore, it is demonstrated with our calculations that the beam splitter proposed here is tolerant to the deviations of incident angle and structure parameters, which make it very easy to be fabricated with current IC technology. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  7. Ultra-small and broadband polarization splitters based on double-slit interference

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chengwei; Li, Hongyun [State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871 (China); Gong, Qihuang; Chen, Jianjun, E-mail: jjchern@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006 (China)

    2016-03-07

    An ultra-small and broadband polarization splitter is numerically and experimentally demonstrated based on the double-slit interference in a polymer-film-coated double-slit structure. The hybrid slab waveguide (air-polymer-Au) supports both the transverse-magnetic and transverse-electric modes. The incident beam from the back side can excite these two guided modes of orthogonally polarized states in the hybrid structure. By exploiting the difference slit widths and the large mode birefringence, these two guided modes propagate to the opposite directions along the front metal surface. Moreover, the short interference length broadens the operation bandwidth. Experimentally, a polarization splitter with a lateral dimension of only about 1.6 μm and an operation bandwidth of 50 nm is realized. By designing the double-slit structure in a hybrid strip waveguide, the device dimension can be significant downscaled to about 0.3 × 1.3 μm{sup 2}. Such an ultra-small and broadband polarization splitter may find important applications in the integrated photonic circuits.

  8. Broadband non-polarizing beam splitter based on guided mode resonance effect

    Science.gov (United States)

    Ma, Jian-Yong; Xu, Cheng; Qiang, Ying-Huai; Zhu, Ya-Bo

    2011-10-01

    A broadband non-polarizing beam splitter (NPBS) operating in the telecommunication C+L band is designed by using the guided mode resonance effect of periodic silicon-on-insulator (SOI) elements. It is shown that this double layer SOI structure can provide ~50/50 beam ratio with the maximum divergences between reflection and transmission being less than 8% over the spectrum of 1.4 μm~1.7 μm and 1% in the telecommunication band for both TE and TM polarizations. The physical basis of this broadband non-polarizing property is on the simultaneous excitation of the TE and TM strong modulation waveguide modes near the designed spectrum band. Meanwhile, the electric field distributions for both TE and TM polarizations verify the resonant origin of spectrum in the periodic SOI structure. Furthermore, it is demonstrated with our calculations that the beam splitter proposed here is tolerant to the deviations of incident angle and structure parameters, which make it very easy to be fabricated with current IC technology.

  9. Thermally tunable broadband omnidirectional and polarization-independent super absorber using phase change material VO2

    Directory of Open Access Journals (Sweden)

    Zhejun Liu

    Full Text Available In this letter, we numerically demonstrate a thermally tunable super absorber by using phase change material VO2 as absorbing layer in metal-insulator-metal structure. An omnidirectional super absorption at λ=2.56μm can be realized by heating the patterned grating VO2 film due to magnetic resonance mechanism. Furthermore, a broadband super absorption higher than 0.8 in the entire 1.6μm–4μm region is achieved when VO2 film is patterned chessboard structure and transformed to metal phase beyond transition temperature. This broadband super absorption can be fulfilled in a wide range of incident angle (0°–70° and under all polarization conditions. Keywords: Phase change material, Metal-insulator-metal, Super absorption, Magnetic resonance

  10. Broadband non-polarizing terahertz beam splitters with variable split ratio

    KAUST Repository

    Wei, Minggui

    2017-08-15

    Seeking effective terahertz functional devices has always aroused extensive attention. Of particular interest is the terahertz beam splitter. Here, we have proposed, designed, manufactured, and tested a broadband non-polarizing terahertz beam splitter with a variable split ratio based on an all-dielectric metasurface. The metasurface was created by patterning a dielectric surface of the N-step phase gradient and etching to a few hundred micrometers. The conversion efficiency as high as 81% under the normal incidence at 0.7 THz was achieved. Meanwhile, such a splitter works well over a broad frequency range. The split ratio of the proposed design can be continuously tuned by simply shifting the metasurface, and the angle of emergences can also be easily adjusted by choosing the step of phase gradients. The proposed design is non-polarizing, and its performance is kept under different polarizations.

  11. Broadband non-polarizing terahertz beam splitters with variable split ratio

    Science.gov (United States)

    Wei, Minggui; Xu, Quan; Wang, Qiu; Zhang, Xueqian; Li, Yanfeng; Gu, Jianqiang; Tian, Zhen; Zhang, Xixiang; Han, Jiaguang; Zhang, Weili

    2017-08-01

    Seeking effective terahertz functional devices has always aroused extensive attention. Of particular interest is the terahertz beam splitter. Here, we have proposed, designed, manufactured, and tested a broadband non-polarizing terahertz beam splitter with a variable split ratio based on an all-dielectric metasurface. The metasurface was created by patterning a dielectric surface of the N-step phase gradient and etching to a few hundred micrometers. The conversion efficiency as high as 81% under the normal incidence at 0.7 THz was achieved. Meanwhile, such a splitter works well over a broad frequency range. The split ratio of the proposed design can be continuously tuned by simply shifting the metasurface, and the angle of emergences can also be easily adjusted by choosing the step of phase gradients. The proposed design is non-polarizing, and its performance is kept under different polarizations.

  12. Broadband non-polarizing terahertz beam splitters with variable split ratio

    KAUST Repository

    Wei, Minggui; Xu, Quan; Wang, Qiu; Zhang, Xueqian; Li, Yanfeng; Gu, Jianqiang; Tian, Zhen; Zhang, Xixiang; Han, Jiaguang; Zhang, Weili

    2017-01-01

    Seeking effective terahertz functional devices has always aroused extensive attention. Of particular interest is the terahertz beam splitter. Here, we have proposed, designed, manufactured, and tested a broadband non-polarizing terahertz beam splitter with a variable split ratio based on an all-dielectric metasurface. The metasurface was created by patterning a dielectric surface of the N-step phase gradient and etching to a few hundred micrometers. The conversion efficiency as high as 81% under the normal incidence at 0.7 THz was achieved. Meanwhile, such a splitter works well over a broad frequency range. The split ratio of the proposed design can be continuously tuned by simply shifting the metasurface, and the angle of emergences can also be easily adjusted by choosing the step of phase gradients. The proposed design is non-polarizing, and its performance is kept under different polarizations.

  13. Dynamically polarized hydrogen target as a broadband, wavelength-independent thermal neutron spin polarizer

    International Nuclear Information System (INIS)

    Zhao Jinkui; Garamus, Vasil M.; Mueller, Wilhelm; Willumeit, Regine

    2005-01-01

    A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8mm thick and consists of 43.4wt% water, 54.6wt% glycerol, and 2wt% of EHBA-Cr(v) complex. The wavelength of the incident neutrons for the transmission experiment was λ=8.1A with Δλ/λ=10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission

  14. Wide-angle, polarization-insensitive and broadband absorber based on eight-fold symmetric SRRs metamaterial

    Science.gov (United States)

    Wu, Dong; Liu, Yumin; Yu, Zhongyuan; Chen, Lei; Ma, Rui; Li, Yutong; Li, Ruifang; Ye, Han

    2016-12-01

    In this paper, we propose a novel three dimensional metamaterial design with eight-fold rotational symmetry that shows a polarization-insensitive, wide-angle and broadband perfect absorption in the microwave band. By simulation, the polarization-insensitive absorption is over 90% between 26.9 GHz to 32.9 GHz, and the broadband absorption remains a good absorption performance to a wide incident angles for both TE and TM polarizations. The magnetic field distribution are investigated to interpret the physical mechanism of broadband absorption. The broadband absorption is based on overlapping the multiple magnetic resonances at the neighboring frequencies by coupling effects of multiple metallic split-ring resonators (SRRs). Moreover, it is demonstrate that the designed structure can be extended to other frequencies by scale down the size of the unit cell, such as the visible frequencies. The simulated results show that the absorption of the smaller absorber is above 90% in the frequency range from 467 THz to 765 THz(392-642 nm), which include orange to purple light in visible region(400-760nm). The wide-angle and polarization-insensitive stabilities of the smaller absorber is also demonstrated at visible region. The proposed work provides a new design of realization of a polarization-insensitive, wide-angle and broadband absorber ranging different frequency bands, and such a structure has potential application in the fields of solar cell, imaging and detection.

  15. A dual-polarized broadband planar antenna and channelizing filter bank for millimeter wavelengths

    Science.gov (United States)

    O'Brient, Roger; Ade, Peter; Arnold, Kam; Edwards, Jennifer; Engargiola, Greg; Holzapfel, William L.; Lee, Adrian T.; Myers, Michael J.; Quealy, Erin; Rebeiz, Gabriel; Richards, Paul; Suzuki, Aritoki

    2013-02-01

    We describe the design, fabrication, and testing of a broadband log-periodic antenna coupled to multiple cryogenic bolometers. This detector architecture, optimized here for astrophysical observations, simultaneously receives two linear polarizations with two octaves of bandwidth at millimeter wavelengths. The broad bandwidth signal received by the antenna is divided into sub-bands with integrated in-line frequency-selective filters. We demonstrate two such filter banks: a diplexer with two sub-bands and a log-periodic channelizer with seven contiguous sub-bands. These detectors have receiver efficiencies of 20%-40% and percent level polarization isolation. Superconducting transition-edge sensor bolometers detect the power in each sub-band and polarization. We demonstrate circularly symmetric beam patterns, high polarization isolation, accurately positioned bands, and high optical efficiency. The pixel design is applicable to astronomical observations of intensity and polarization at millimeter through sub-millimeter wavelengths. As compared with an imaging array of pixels measuring only one band, simultaneous measurements of multiple bands in each pixel has the potential to result in a higher signal-to-noise measurement while also providing spectral information. This development facilitates compact systems with high mapping speeds for observations that require information in multiple frequency bands.

  16. Ultra-broadband and high-efficiency polarization conversion metasurface with multiple plasmon resonance modes

    Science.gov (United States)

    Dong, Guo-Xiang; Shi, Hong-Yu; Xia, Song; Li, Wei; Zhang, An-Xue; Xu, Zhuo; Wei, Xiao-Yong

    2016-08-01

    In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency, covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%. At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471292, 61331005, 61471388, 51277012, 41404095, and 61501365), the 111 Project, China (Grant No. B14040), the National Basic Research Program of China (Grant No. 2015CB654602), and the China Postdoctoral Science Foundation ( Grant No. 2015M580849).

  17. Compact broadband polarization beam splitter using a symmetric directional coupler with sinusoidal bends.

    Science.gov (United States)

    Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F

    2017-01-15

    We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.

  18. Scattering Fields Control by Metamaterial Device Based on Ultra-Broadband Polarization Converters

    Directory of Open Access Journals (Sweden)

    Si-Jia Li

    2016-12-01

    Full Text Available We proposed a novel ultra-broadband meta¬material screen with controlling the electromagnetic scat¬tering fields based on the three layers wideband polariza¬tion converter (TLW-PC. The unit cell of TLW-PC was composed of a three layers substrate loaded with double metallic split-rings structure and a metal ground plane. We observed that the polarization converter primarily per¬formed ultra-broadband cross polarization conversion from 5.71 GHz to 14.91 GHz. Furthermore, a metamaterial screen, which contributed to the low scattering charac¬teristics, had been exploited with the orthogonal array based on TLW-PC. The near scattering electronic fields are controlled due to the change of phase and amplitude for incident wave. The metamaterial screen significantly exhibited low scattering characteristics from 5.81 GHz to 15.06 GHz. To demonstrate design, a metamaterial device easily implemented by the common printed circuit board method has been fabricated and measured. Experimental results agreed well with the simulated results.

  19. Flexible and conformable broadband metamaterial absorber with wide-angle and polarization stability for radar application

    Science.gov (United States)

    Chen, Huijie; Yang, Xiaoqing; Wu, Shiyue; Zhang, Di; Xiao, Hui; Huang, Kama; Zhu, Zhanxia; Yuan, Jianping

    2018-01-01

    In this work, a type of flexible, broadband electromagnetic microwave absorber is designed, fabricated and experimentally characterized. The absorber is composed of lumped resistors loaded frequency selective surface which is mounted on flexible substrate using silicone rubber and in turn backed by copper film. The simulated results show that an effective absorption (over 90%) bandwidth spans from 7.6 to 18.3 GHz, which covers both X (8-12 GHz) and Ku (12-18 GHz) bands, namely a 82.6% fraction bandwidth. And the bandwidth performs a good absorption response by varying the incident angle up to 60° for both TE and TM polarization. Moreover, the flexibility of the substrate enables the absorber conformably to bend and attach to cylinders of various radius without breakdown of the absorber. The designed structure has been fabricated and measured for both planar and conformable cases, and absorption responses show a good agreement of the broadband absorption feature with the simulated ones. This work has demonstrated specifically that proposed structure provides polarization-insensitive, wide-angle, flexible and conformable wideband absorption, which extends the absorber’s application to practical radar cross section reductions for radars and warships.

  20. Polarization-sensitive and broadband germanium sulfide photodetectors with excellent high-temperature performance.

    Science.gov (United States)

    Tan, Dezhi; Zhang, Wenjin; Wang, Xiaofan; Koirala, Sandhaya; Miyauchi, Yuhei; Matsuda, Kazunari

    2017-08-31

    Layered materials, such as graphene, transition metal dichalcogenides and black phosphorene, have been established rapidly as intriguing building blocks for optoelectronic devices. Here, we introduce highly polarization sensitive, broadband, and high-temperature-operation photodetectors based on multilayer germanium sulfide (GeS). The GeS photodetector shows a high photoresponsivity of about 6.8 × 10 3 A W -1 , an extremely high specific detectivity of 5.6 × 10 14 Jones, and broad spectral response in the wavelength range of 300-800 nm. More importantly, the GeS photodetector has high polarization sensitivity to incident linearly polarized light, which provides another degree of freedom for photodetectors. Tremendously enhanced photoresponsivity is observed with a temperature increase, and high responsivity is achievable at least up to 423 K. The establishment of larger photoinduced reduction of the Schottky barrier height will be significant for the investigation of the photoresponse mechanism of 2D layered material-based photodetectors. These attributes of high photocurrent generation in a wide temperature range, broad spectral response, and polarization sensitivity coupled with environmental stability indicate that the proposed GeS photodetector is very suitable for optoelectronic applications.

  1. SCRLH-TL Based Sequential Rotation Feed Network for Broadband Circularly Polarized Antenna Array

    Directory of Open Access Journals (Sweden)

    B. F. Zong

    2016-04-01

    Full Text Available In this paper, a broadband circularly polarized (CP microstrip antenna array using composite right/left-handed transmission line (SCRLH-TL based sequential rotation (SR feed network is presented. The characteristics of a SCRLH-TL are initially investigated. Then, a broadband and low insertion loss 45º phase shifter is designed using the SCRLH-TL and the phase shifter is employed in constructing a SR feed network for CP antenna array. To validate the design method of the SR feed network, a 2×2 antenna array comprising sequentially rotated coupled stacked CP antenna elements is designed, fabricated and measured. Both the simulated and measured results indicate that the performances of the antenna element are further enhanced when the SR network is used. The antenna array exhibits the VSWR less than 1.8 dB from 4 GHz to 7 GHz and the 3 dB axial ratio (AR from 4.4 GHz to 6.8 GHz. Also, high peak gain of 13.7 dBic is obtained. Besides, the normalized radiation patterns at the operating frequencies are symmetrical and the side lobe levels are low at φ=0º and φ=90º.

  2. NONLINEAR REFLECTION PROCESS OF LINEARLY POLARIZED, BROADBAND ALFVÉN WAVES IN THE FAST SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Shoda, M.; Yokoyama, T., E-mail: shoda@eps.s.u-tokyo.ac.jp [Department of Earth and Planetary Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2016-04-01

    Using one-dimensional numerical simulations, we study the elementary process of Alfvén wave reflection in a uniform medium, including nonlinear effects. In the linear regime, Alfvén wave reflection is triggered only by the inhomogeneity of the medium, whereas in the nonlinear regime, it can occur via nonlinear wave–wave interactions. Such nonlinear reflection (backscattering) is typified by decay instability. In most studies of decay instabilities, the initial condition has been a circularly polarized Alfvén wave. In this study we consider a linearly polarized Alfvén wave, which drives density fluctuations by its magnetic pressure force. For generality, we also assume a broadband wave with a red-noise spectrum. In the data analysis, we decompose the fluctuations into characteristic variables using local eigenvectors, thus revealing the behaviors of the individual modes. Different from the circular-polarization case, we find that the wave steepening produces a new energy channel from the parent Alfvén wave to the backscattered one. Such nonlinear reflection explains the observed increasing energy ratio of the sunward to the anti-sunward Alfvénic fluctuations in the solar wind with distance against the dynamical alignment effect.

  3. Exciton versus Free Carrier Photogeneration in Organometal Trihalide Perovskites Probed by Broadband Ultrafast Polarization Memory Dynamics

    Science.gov (United States)

    Sheng, ChuanXiang; Zhang, Chuang; Zhai, Yaxin; Mielczarek, Kamil; Wang, Weiwei; Ma, Wanli; Zakhidov, Anvar; Vardeny, Z. Valy

    2015-03-01

    We studied the ultrafast transient response of photoexcitations in two hybrid organic-inorganic perovskite films used for high efficiency photovoltaic cells, namely, CH3NH3PbI3 and CH3NH3PbI1.1Br1.9 using polarized broadband pump-probe spectroscopy in the spectral range of 0.3-2.7 eV with 300 fs time resolution. For CH3NH3PbI3 with above-gap excitation we found both photogenerated carriers and excitons, but only carriers are photogenerated with below-gap excitation. In contrast, mainly excitons are photogenerated in CH3NH3PbI1.1Br1.9 . Surprisingly, we also discovered in CH3NH3PbI3 , but not in CH3NH3PbI1.1Br1.9 , transient photoinduced polarization memory for both excitons and photocarriers, which is also reflected in the steady state photoluminescence. From the polarization memory dynamics we obtained the excitons diffusion constant in CH3NH3PbI3 , D ≈0.01 cm2 s-1 .

  4. CIRCULARLY POLARIZED SLOTTED APERTURE ANTENNA WITH COPLANAR WAVEGUIDE FED FOR BROADBAND APPLICATIONS

    Directory of Open Access Journals (Sweden)

    B. T. P. MADHAV

    2016-02-01

    Full Text Available Coplanar waveguide fed circularly polarized microstrip patch antenna performance evaluation is presented in this paper. The broadband characteristics are attained by placing open end slot at the lower side of the antenna. The proposed design has the return loss of less than -10dB and VSWR<2 in the desired band of operation. A gain of 3dB to 4dB is attained in the desired band with good radiation characteristics and a suitable axial ratio of less than 3 dB is attained in the prescribed band of operation. Proposed antenna is fabricated on the FR4 substrate with dielectric constant of 4.4. Parametric analysis with change in substrate permittivity also performed and the optimized dimensions are presented in this work.

  5. Broadband and Broad-angle Polarization-independent Metasurface for Radar Cross Section Reduction.

    Science.gov (United States)

    Sun, Hengyi; Gu, Changqing; Chen, Xinlei; Li, Zhuo; Liu, Liangliang; Xu, Bingzheng; Zhou, Zicheng

    2017-01-20

    In this work, a broadband and broad-angle polarization-independent random coding metasurface structure is proposed for radar cross section (RCS) reduction. An efficient genetic algorithm is utilized to obtain the optimal layout of the unit cells of the metasurface to get a uniform backscattering under normal incidence. Excellent agreement between the simulation and experimental results show that the proposed metasurface structure can significantly reduce the radar cross section more than 10 dB from 17 GHz to 42 GHz when the angle of incident waves varies from 10° to 50°. The proposed coding metasurface provides an efficient scheme to reduce the scattering of the electromagnetic waves.

  6. Ultrashort broadband polarization beam splitter based on a combined hybrid plasmonic waveguide.

    Science.gov (United States)

    Chang, Ken-Wei; Huang, Chia-Chien

    2016-01-20

    We propose an ultracompact broadband polarization beam splitter (PBS) based on a combined hybrid plasmonic waveguide (HPW). The proposed PBS separates transverse-electric (TE) and transverse-magnetic (TM) modes using a bent lower HPW with vertical nanoscale gaps and a straight upper HPW with a horizontal nanoscale gap, respectively, without relying on an additional coupling region. This design considerably reduces the length of the PBS to the submicron scale (920 nm, the shortest PBS reported to date) while offering polarization extinction ratios (PERs) of ~19 dB (~18 dB) and insertion losses (ILs) of ~0.6 dB (~0.3 dB) for the TE (TM) mode over an extremely broad band of 400 nm (from λ = 1300 nm to 1700 nm, covering entirely second and third telecom windows). The length of the designed PBS can be reduced further to 620 nm while still offering PERs of 15 dB, realizing a densely photonic integrated circuit. Considering the fabrication tolerance, the designed PBS allows for large geometrical deviations of ± 20 nm while restricting PER variations to within 1 dB, except for those in the nanoscale gaps smaller than 10nm. Additionally, we also address the input and ouput coupling efficiencies of the proposed PBS.

  7. A nonuniform-polarization high-energy ultra-broadband laser with a long erbium-doped fiber

    International Nuclear Information System (INIS)

    Mao, Dong

    2013-01-01

    We have experimentally investigated nonuniformly polarized broadband high-energy pulses delivered from a mode-locked laser with an ultra-long erbium-doped fiber (EDF). The pulses exhibit a broadband spectrum of ∼73 nm and can avoid optical wave breaking at high-pump regimes. The polarization states of the pulses evolve from uniform to nonuniform at each round trip in the oscillator, which is distinct from other pulses. Remarkably, the output pulses broaden in anomalous- or normal-dispersion regimes while they can be shortened with an EDF amplifier external to the cavity. Our results suggest that the long EDF results in a nonuniform-polarization state and plays a decisive role in the formation of high-energy pulses. (paper)

  8. Relations between broad-band linear polarization and Ca II H and K emission in late-type dwarf stars

    Science.gov (United States)

    Huovelin, Juhani; Saar, Steven H.; Tuominen, Ilkka

    1988-01-01

    Broadband UBV linear polarization data acquired for a sample of late-type dwarfs are compared with contemporaneous measurements of Ca II H and K line core emission. A weighted average of the largest values of the polarization degree is shown to be the best parameter for chromospheric activity diagnosis. The average maximum polarization in the UV is found to increase from late-F to late-G stars. It is noted that polarization in the U band is considerably more sensitive to activity variations than that in the B or V bands. The results indicate that stellar magnetic fields and the resulting saturation in the Zeeman-sensitive absorption lines are the most probably source of linear polarization in late-type main-sequence stars.

  9. Broadband Circularly Polarized Slot Antenna Loaded by a Multiple-Circular-Sector Patch.

    Science.gov (United States)

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2018-05-15

    In this paper, a microstrip-fed broadband circularly polarized (CP) slot antenna is presented. CP operation can be attained simply by embedding an S-shaped strip. By loading with a multiple-circular-sector patch, which consists of 12 circular-sector patches with identical central angles of 30° and different radii, the 3 dB axial ratio (AR) bandwidth is significantly broadened. To validate the performance of the proposed antenna, an antenna prototype is fabricated and tested. The fabricated antenna is 54 mm × 54 mm × 0.8 mm in size. The measured -10 dB reflection and 3 dB AR bandwidths are 81.06% (1.68⁻3.97 GHz) and 70.55% (1.89⁻3.95 GHz), respectively. Within the 3 dB AR bandwidth, the measured peak gain is 3.81 dBic. Reasonable agreement is also obtained between the measured and simulated results.

  10. Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

    Science.gov (United States)

    Li, Long; Zhou, Xiaoxiao

    2018-03-23

    In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

  11. Broadband silicon polarization beam splitter with a high extinction ratio using a triple-bent-waveguide directional coupler.

    Science.gov (United States)

    Ong, Jun Rong; Ang, Thomas Y L; Sahin, Ezgi; Pawlina, Bryan; Chen, G F R; Tan, D T H; Lim, Soon Thor; Png, Ching Eng

    2017-11-01

    We report on the design and experimental demonstration of a broadband silicon polarization beam splitter (PBS) with a high extinction ratio (ER)≥30  dB. This was achieved using triple-bent-waveguide directional coupling in a single PBS, and cascaded PBS topology. For the single PBS, the bandwidths for an ER≥30  dB are 20 nm for the quasi-TE mode, and 70 nm for the quasi-TM mode when a broadband light source (1520-1610 nm) was employed. The insertion loss (IL) varies from 0.2 to 1 dB for the quasi-TE mode and 0.2-2 dB for the quasi-TM mode. The cascaded PBS improved the bandwidth of the quasi-TE mode for an ER≥30  dB to 90 nm, with a low IL of 0.2-2 dB. To the best of our knowledge, our PBS system is one of the best broadband PBSs with an ER as high as ∼42  dB and a low IL below 1 dB around the central wavelength, and experimentally demonstrated using edge-coupling.

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

    DEFF Research Database (Denmark)

    Canning, John; Skivesen, Nina; Kristensen, Martin

    2007-01-01

    Both quasi-TE and TM polarisation spectra for a silicon- on-insulator (SOI) waveguide are recorded over (1100-1700) nm using a broadband supercontinuum source. By studying both the input and output polarisation eigenstates we observe narrowband resonant cross coupling near the lowest quasi-TE mode...... cut-off. We also observe relatively broadband mixing between the two eigenstates to generate a complete photonic bandgap. By careful analysis of the output polarisation state we report on an inherent non-reciprocity between quasi TE and TM fundamental mode cross coupling. The nature of polarisation...

  13. Broadband spectral shaping in regenerative amplifier based on modified polarization-encoded chirped pulse amplification

    Science.gov (United States)

    Wang, Xinliang; Lu, Xiaoming; Liu, Yanqi; Xu, Yi; Wang, Cheng; Li, Shuai; Yu, Linpeng; Liu, Xingyan; Liu, Keyang; Xu, Rongjie; Leng, Yuxin

    2018-06-01

    We present an intra-cavity spectral shaping method to suppress the spectral narrowing in a Ti:sapphire (Ti:Sa) regenerative amplifier. The spectral shaping is realized by manipulating the stored energies of two Ti:Sa crystals with orthogonal c-axes, changing the length of a quartz plate, and rotating a broadband achromatic half-wave plate. Using this method, in our proof-of-concept experiment, an 84-nm-(FWHM)-broadband amplified pulse with an energy gain larger than 106 is obtained, which supports a 17.8 fs Fourier-transform-limited pulse duration. The pulse is compressed to 18.9 fs.

  14. Unidirectional cross polarization rotator with enhanced broadband transparency by cascading twisted nanobars

    International Nuclear Information System (INIS)

    Wang, Ying-Hua; Shao, Jian; Li, Jie; Zhu, Ming-Jie; Li, Jiaqi; Dong, Zheng-Gao

    2016-01-01

    We demonstrate the optical activity for linear polarization by twisting cascading multilayer nanobars, for which the x- (y-)polarized light is significantly transformed to a y- (x-)polarized one with enhanced transmittance in a unidirectional manner, and the bandwidth can be broadened by increasing the cascading number of layers. The polarization conversion rate reaches nearly 100% with a maximum cross-polarization transmission coefficient larger than 0.95. This phenomenon is attributed to the chiral structural arrangement and anisotropic resonance of nanobars, which consequently leads to different cross-polarization conversions between forward and backward incident lights, and thus the unidirectional transmission with an extinction ratio up to 10 3 . These characteristics show application potential in optical nano-devices. (paper)

  15. Broadband polarized emission from P(NDI2OD-T2) polymer.

    Science.gov (United States)

    Ulrich, Steve; Sutch, Tabitha; Szulczewski, Greg; Schweizer, Matthias; Barbosa, Newton; Araujo, Paulo

    2018-05-18

    We investigate the P(NDI2OD-T2) photophysical properties via absorbance and fluorescence spectroscopy, in association with the experimental approach baptized Stokes Spectroscopy, which provides valuable material information through the acquisition and analysis of the fluorescence polarization degree. By changing solvents and using different samples such as solutions, thick, and thin films, it is possible to control the polarization degree spectrum associated to the fluorescence emitted by the polymer's isolated chains and aggregates. We show that the polarization degree could become a powerful tool to obtain information related to the samples morphology, which is connected to their microscopic structure. Moreover, the polarization degree spectra suggest that depolarization effects linked to energy and charge transfer mechanisms are likely taking place. Our findings indicate that P(NDI2OD-T2) polymers are excellent candidates for the advancement of organic technologies that rely on the emission and detection of polarized lights. © 2018 IOP Publishing Ltd.

  16. Generation of a mid-infrared broadband polarized supercontinuum in As2Se3 photonic crystal fibers

    International Nuclear Information System (INIS)

    Wang Xiao-Yan; Li Shu-Guang; Liu Shuo; Yin Guo-Bing; Li Jian-She

    2012-01-01

    A simplified structure of birefringent chalcogenide As 2 Se 3 photonic crystal fiber (PCF) is designed. Properties of birefringence, polarization extinction ratio, chromatic dispersion, nonlinear coefficient, and transmission are studied by using the multipole method, the finite-difference beam propagation method, and the adaptive split-step Fourier method. Considering that the zero dispersion wavelength of our proposed fiber is about 4 μm, we have analysed the mechanism of spectral broadening in PCFs with different pitches in detail, with femtosecond pulses at a wavelength of 4 μm as the pump pulses. Especially, mid-infrared broadband polarized supercontinuums are obtained in a 3-cm PCF with an optimal pitch of 2 μm. Their spectral width at −20 dB reaches up to 12 μm. In the birefringent PCF, we find that the supercontinuum generation changes with the pump alignment angle. Research results show that no coupling between eigenpolarization modes are observed at the maximum average power (i.e., 37 mW), which indicates that the polarization state is well maintained. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  17. High-efficiency broadband polarization converter based on Ω-shaped metasurface

    Science.gov (United States)

    Zhang, Tianyao; Huang, Lingling; Li, Xiaowei; Liu, Juan; Wang, Yongtian

    2017-11-01

    The polarization state, which cannot be directly detected by human eyes, forms an important characteristic of electromagnetic waves. Control of polarization states has long been pursued for various applications. Conventional polarization converters can hardly meet the requirements in lab-on-chip systems, due to the involvement of bulk materials. Here, we propose the design and realization of a linear to circular polarization converter based on metasurfaces. The metasurface is deliberately designed using achiral two-fold mirror symmetry Ω-shaped antennas. The converter integrates a ground metal plane, a spacer dielectric layer and an antenna array, leading to a high conversion efficiency and broad operating bandwidth in the near infrared regime. The calculated Stokes parameters indicate an excellent conversion of linear to circular polarization for the reflected light. The tunability of the bandwidth by oblique incidence and by modulating the thickness of the dielectric layer is also introduced and demonstrated, which shows great flexibilities for such metasurface converters. The proposed metasurface may open up intriguing possibilities towards the realization of ultrathin nanophotonic devices for polarization manipulation and wavefront engineering.

  18. Tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated photonic crystal fiber

    Science.gov (United States)

    Liu, Yingchao; Chen, Hailiang; Ma, Mingjian; Zhang, Wenxun; Wang, Yujun; Li, Shuguang

    2018-03-01

    We propose a tunable ultra-broadband polarization filter based on three-core resonance of the fluid-infiltrated and gold-coated high birefringent photonic crystal fiber (HB-PCF). Gold film was applied to the inner walls of two cladding air holes and surface plasmon polaritons were generated on its surface. The two gold-coated cladding air holes acted as two defective cores. As the phase matching condition was satisfied, light transmitted in the fiber core and coupled to the two defective cores. The three-core PCF supported three super modes in two orthogonal polarization directions. The coupling characteristics among these modes were investigated using the finite-element method. We found that the coupling wavelengths and strength between these guided modes can be tuned by altering the structural parameters of the designed HB-PCF, such as the size of the voids, thickness of the gold-films and liquid infilling pattern. Under the optimized structural parameters, a tunable broadband polarization filter was realized. For one liquid infilling pattern, we obtained a broadband polarization filter which filtered out the light in y-polarization direction at the wavelength of 1550 nm. For another liquid infilling pattern, we filtered out light in the x-polarization direction at the wavelength of 1310 nm. Our studies on the designed HB-PCF made contributions to the further devising of tunable broadband polarization filters, which are extensively used in telecommunication and sensor systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505175 and 61475134) and the Natural Science Foundation of Hebei Province (Grant Nos. F2017203110 and F2017203193).

  19. Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

    Science.gov (United States)

    Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

    2015-06-01

    Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

  20. A STUDY OF BROADBAND FARADAY ROTATION AND POLARIZATION BEHAVIOR OVER 1.3–10 GHz IN 36 DISCRETE RADIO SOURCES

    International Nuclear Information System (INIS)

    Anderson, C. S.; Gaensler, B. M.; Feain, I. J.

    2016-01-01

    We present a broadband polarization analysis of 36 discrete polarized radio sources over a very broad, densely sampled frequency band. Our sample was selected on the basis of polarization behavior apparent in narrowband archival data at 1.4 GHz: half the sample shows complicated frequency-dependent polarization behavior (i.e., Faraday complexity) at these frequencies, while half shows comparatively simple behavior (i.e., they appear Faraday simple ). We re-observed the sample using the Australia Telescope Compact Array in full polarization, with 6 GHz of densely sampled frequency coverage spanning 1.3–10 GHz. We have devised a general polarization modeling technique that allows us to identify multiple polarized emission components in a source, and to characterize their properties. We detect Faraday complex behavior in almost every source in our sample. Several sources exhibit particularly remarkable polarization behavior. By comparing our new and archival data, we have identified temporal variability in the broadband integrated polarization spectra of some sources. In a number of cases, the characteristics of the polarized emission components, including the range of Faraday depths over which they emit, their temporal variability, spectral index, and the linear extent of the source, allow us to argue that the spectropolarimetric data encode information about the magneto-ionic environment of active galactic nuclei themselves. Furthermore, the data place direct constraints on the geometry and magneto-ionic structure of this material. We discuss the consequences of restricted frequency bands on the detection and interpretation of polarization structures, and the implications for upcoming spectropolarimetric surveys.

  1. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Science.gov (United States)

    Barho, Franziska B.; Gonzalez-Posada, Fernando; Milla, Maria-Jose; Bomers, Mario; Cerutti, Laurent; Tournié, Eric; Taliercio, Thierry

    2017-11-01

    Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA) spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR) with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  2. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Directory of Open Access Journals (Sweden)

    Barho Franziska B.

    2017-11-01

    Full Text Available Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  3. Broadbanding of circularly polarized patch antenna by waveguided magneto-dielectric metamaterial

    Directory of Open Access Journals (Sweden)

    Xin Mi Yang

    2015-12-01

    Full Text Available Design of bandwidth-enhanced circularly polarized (CP patch antenna using artificial magneto-dielectric substrate was investigated. The artificial magneto-dielectric material adopted here takes the form of waveguided metamaterial (WG-MTM. In particular, the embedded meander line (EML structure was employed as the building element of the WG-MTM. As verified by the retrieved effective medium parameters, the EML-based waveguided magneto-dielectric metamaterial (WG-MDM exhibits two-dimensionally isotropic magneto-dielectric property with respect to TEM wave excitations applied in two orthogonal directions. A CP patch antenna loaded with the EML-based WG-MDM (WG-MDM antenna has been proposed and its design procedure is described in detail. Simulation results show that the impedance and axial ratio bandwidths of the WG-MDM antenna have increased by 125% and 133%, respectively, compared with those obtained with pure dielectric substrate offering the same patch size. The design of the novel WG-MDM antenna was also validated by measurement results, which show good agreement with their simulated counterparts.

  4. Broadband Access

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Broadband Access. Worldwide market for broadband access $30 Billion! Over 200 million broadband subscribers worldwide! Various Competing Broadband access. Digital Subscriber line; Wireless; Optical Fiber.

  5. Proposal of a broadband, polarization-insensitive and high-efficiency hot-carrier schottky photodetector integrated with a plasmonic silicon ridge waveguide

    International Nuclear Information System (INIS)

    Yang, Liu; Kou, Pengfei; Shen, Jianqi; Lee, El Hang; He, Sailing

    2015-01-01

    We propose a broadband, polarization-insensitive and high-efficiency plasmonic Schottky diode for detection of sub-bandgap photons in the optical communication wavelength range through internal photoemission (IPE). The distinctive features of this design are that it has a gold film covering both the top and the sidewalls of a dielectric silicon ridge waveguide with the Schottky contact formed at the gold–silicon interface and the sidewall coverage of gold can be easily tuned by an insulating layer. An extensive physical model on IPE of hot carriers is presented in detail and is applied to calculate and examine the performance of this detector. In comparison with a diode having only the top gold contact, the polarization sensitivity of the responsivity is greatly minimized in our photodetector with gold film covering both the top and the sidewall. Much higher responsivities for both polarizations are also achieved over a broad wavelength range of 1.2–1.6 μm. Moreover, the Schottky contact is only 4 μm long, leading to a very small dark current. Our design is very promising for practical applications in high-density silicon photonic integration. (paper)

  6. Polarization-sensitive electro-optic detection of terahertz wave using three different types of crystal symmetry: Toward broadband polarization spectroscopy

    International Nuclear Information System (INIS)

    Oguchi, Kenichi; Iwasaki, Hotsumi; Okano, Makoto; Watanabe, Shinichi

    2016-01-01

    We investigated polarization-sensitive electro-optic (EO) detection of terahertz (THz) waves by using two uniaxial crystals: a c-cut gallium selenide and a c-cut lithium niobate crystals. We formulated a general frequency-domain description of EO detection by in-plane isotropic EO crystals, which holds regardless of the frequency. Based on this description, the polarization of THz waves can be derived by analyzing EO sampling signals measured with two orthogonal configurations of the in-plane isotropic EO crystals as well as typical (111) zinc-blende EO crystals. In addition, we experimentally demonstrated that the frequency-dependent polarization of THz waves can be reproducibly retrieved using three EO crystals with different crystal symmetries and with different phase matching conditions. Our description provides essential information for practical polarization sensing in the THz frequency range as well as in the mid-infrared range

  7. Light reflection by the cuticle of C. aurigans scarabs: a biological broadband reflector of left handed circularly polarized light

    Science.gov (United States)

    Libby, E.; Azofeifa, D. E.; Hernández-Jiménez, M.; Barboza-Aguilar, C.; Solís, A.; García-Aguilar, I.; Arce-Marenco, L.; Hernández, A.; Vargas, W. E.

    2014-08-01

    Measured reflection spectra from elytra of Chrysina aurigans scarabs are reported. They show a broad reflection band for wavelengths from 0.525 to 1.0 μm with a sequence of maxima and minima reflection values superimposed on a mean value of around 40% for the high reflection band. Different mechanisms contributing to the reflection spectra have been considered, with the dominant effect, reflection of left handed circularly polarized light, being produced by a laminated left handed twisted structure whose pitch changes with depth through the procuticle in a more complex way than that characterizing broad band circular polarizers based on cholesteric liquid crystals.

  8. Light reflection by the cuticle of C. aurigans scarabs: a biological broadband reflector of left handed circularly polarized light

    International Nuclear Information System (INIS)

    Libby, E; Azofeifa, D E; Hernández-Jiménez, M; García-Aguilar, I; Arce-Marenco, L; Hernández, A; Vargas, W E; Barboza-Aguilar, C; Solís, A

    2014-01-01

    Measured reflection spectra from elytra of Chrysina aurigans scarabs are reported. They show a broad reflection band for wavelengths from 0.525 to 1.0 μm with a sequence of maxima and minima reflection values superimposed on a mean value of around 40% for the high reflection band. Different mechanisms contributing to the reflection spectra have been considered, with the dominant effect, reflection of left handed circularly polarized light, being produced by a laminated left handed twisted structure whose pitch changes with depth through the procuticle in a more complex way than that characterizing broad band circular polarizers based on cholesteric liquid crystals. (fast track communication)

  9. On-chip broadband ultra-compact optical couplers and polarization splitters based on off-centered and non-symmetric slotted Si-wire waveguides

    Science.gov (United States)

    Haldar, Raktim; Mishra, V.; Dutt, Avik; Varshney, Shailendra K.

    2016-10-01

    In this work, we propose novel schemes to design on-chip ultra-compact optical directional couplers (DC) and broadband polarization beam splitters (PBS) based on off-centered and asymmetric dielectric slot waveguides, respectively. Slot dimensions and positions are optimized to achieve maximum coupling coefficients between two symmetric and non-symmetric slotted Si wire waveguides through overlap integral method. We observe >88% of enhancement in the coupling coefficients when the size-optimized slots are placed in optimal positions, with respect to the same waveguides with no slot. When the waveguides are parallel, in that case, a coupling length as short as 1.73 μm is accomplished for TM mode with the off-centered and optimized slots. This scheme enables us to design optical DC with very small footprint, L c ∼ 0.9 μm in the presence of S-bends. We also report a compact (L c ∼ 1.1 μm) on-chip broadband PBS with hybrid slots. Extinction ratios of 13 dB and 22.3 dB are realized with very low insertion loss (0.055 dB and 0.008 dB) for TM and TE modes at 1.55 μm, respectively. The designed PBS exhibits a bandwidth of 78 nm for the TM mode (C-and partial L-bands) and >100 nm for the TE mode (S + C + L wavelength bands). Such on-chip devices can be used to design compact photonic interconnects and quantum information processing units efficiently. We have also investigated the fabrication tolerances of the proposed devices and described the fabrication steps to realize such hybrid devices. Our results are in good agreement with 3D FDTD simulations.

  10. Broadband photonic single sideband frequency up-converter based on the cross polarization modulation effect in a semiconductor optical amplifier for radio-over-fiber systems.

    Science.gov (United States)

    Lee, Seung-Hun; Kim, Hyoung-Jun; Song, Jong-In

    2014-01-13

    A broadband photonic single sideband (SSB) frequency up-converter based on the cross polarization modulation (XPolM) effect in a semiconductor optical amplifier (SOA) is proposed and experimentally demonstrated. An optical radio frequency (RF) signal in the form of an optical single sideband (OSSB) is generated by the photonic SSB frequency up-converter to solve the power fading problem caused by fiber chromatic dispersion. The generated OSSB RF signal has almost identical optical carrier power and optical sideband power. This SSB frequency up-conversion scheme shows an almost flat electrical RF power response as a function of the RF frequency in a range from 31 GHz to 75 GHz after 40 km single mode fiber (SMF) transmission. The photonic SSB frequency up-conversion technique shows negligible phase noise degradation. The phase noise of the up-converted RF signal at 49 GHz for an offset of 10 kHz is -93.17 dBc/Hz. Linearity analysis shows that the photonic SSB frequency up-converter has a spurious free dynamic range (SFDR) value of 79.51 dB · Hz(2/3).

  11. Broadband cross-polarization-based heteronuclear dipolar recoupling for structural and dynamic NMR studies of rigid and soft solids

    International Nuclear Information System (INIS)

    Kharkov, B. B.; Chizhik, V. I.; Dvinskikh, S. V.

    2016-01-01

    Dipolar recoupling is an essential part of current solid-state NMR methodology for probing atomic-resolution structure and dynamics in solids and soft matter. Recently described magic-echo amplitude- and phase-modulated cross-polarization heteronuclear recoupling strategy aims at efficient and robust recoupling in the entire range of coupling constants both in rigid and highly dynamic molecules. In the present study, the properties of this recoupling technique are investigated by theoretical analysis, spin-dynamics simulation, and experimentally. The resonance conditions and the efficiency of suppressing the rf field errors are examined and compared to those for other recoupling sequences based on similar principles. The experimental data obtained in a variety of rigid and soft solids illustrate the scope of the method and corroborate the results of analytical and numerical calculations. The technique benefits from the dipolar resolution over a wider range of coupling constants compared to that in other state-of-the-art methods and thus is advantageous in studies of complex solids with a broad range of dynamic processes and molecular mobility degrees

  12. Visible light broadband perfect absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

    2016-03-15

    The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

  13. Proton polarization above 70% by DNP using photo-excited triplet states, a first step towards a broadband neutron spin filter

    International Nuclear Information System (INIS)

    Eichhorn, T.R.; Niketic, N.; Brandt, B. van den; Filges, U.; Panzner, T.; Rantsiou, E.; Wenckebach, W.Th.; Hautle, P.

    2014-01-01

    The use of polarized protons as neutron spin filter is an attractive alternative to the well established neutron polarization techniques, as the large, spin-dependent neutron scattering cross-section for protons is useful up to the sub-MeV region. Employing optically excited triplet states for the dynamic nuclear polarization (DNP) of the protons relieves the stringent requirements of classical DNP schemes, i.e low temperatures and strong magnetic fields, making technically simpler systems with open geometries possible. Using triplet DNP a record polarization of 71% has been achieved in a pentacene doped naphthalene single crystal at a field of 0.36 T using a simple helium flow cryostat for cooling. Furthermore, by placing the polarized crystal in a neutron optics focus and de-focus scheme, the actual sample cross-section could be increased by a factor 35 corresponding to an effective spin filter cross-section of 18×18mm 2

  14. Proton polarization above 70% by DNP using photo-excited triplet states, a first step towards a broadband neutron spin filter

    Energy Technology Data Exchange (ETDEWEB)

    Eichhorn, T.R. [Laboratory for Developments and Methods (LDM), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Laboratory of Functional and Metabolic Imaging, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Niketic, N.; Brandt, B. van den; Filges, U.; Panzner, T.; Rantsiou, E.; Wenckebach, W.Th. [Laboratory for Developments and Methods (LDM), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Hautle, P., E-mail: patrick.hautle@psi.ch [Laboratory for Developments and Methods (LDM), Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-08-01

    The use of polarized protons as neutron spin filter is an attractive alternative to the well established neutron polarization techniques, as the large, spin-dependent neutron scattering cross-section for protons is useful up to the sub-MeV region. Employing optically excited triplet states for the dynamic nuclear polarization (DNP) of the protons relieves the stringent requirements of classical DNP schemes, i.e low temperatures and strong magnetic fields, making technically simpler systems with open geometries possible. Using triplet DNP a record polarization of 71% has been achieved in a pentacene doped naphthalene single crystal at a field of 0.36 T using a simple helium flow cryostat for cooling. Furthermore, by placing the polarized crystal in a neutron optics focus and de-focus scheme, the actual sample cross-section could be increased by a factor 35 corresponding to an effective spin filter cross-section of 18×18mm{sup 2}.

  15. Adoption of Broadband Services

    DEFF Research Database (Denmark)

    Falch, Morten

    2008-01-01

    Broadband is seen as a key infrastructure for developing the information society. For this reason many Governments are actively engaged in stimulating investments in broadband infrastructures and use of broadband services. This chapter compares a wide range of broadband strategies in the most suc....... Many countries have provided active support for stimulating diffusion of broadband and national variants of this type of policies in different countries are important for an explanation of national differences in adoption of broadband....

  16. Ultra-Broadband Silicon-Wire Polarization Beam Combiner/Splitter Based on a Wavelength Insensitive Coupler With a Point-Symmetrical Configuration

    OpenAIRE

    Uematsu, Takui; Kitayama, Tetsuya; Ishizaka, Yuhei; Saitoh, Kunimasa

    2014-01-01

    An ultrabroadband silicon wire polarization beam combiner/splitter (PBCS) based on a wavelength-insensitive coupler is proposed. The proposed PBCS consists of three identical directional couplers and two identical delay lines. We design the PBCS using the 3-D finite element method. Numerical simulations show that the proposed PBCS can achieve the transmittance of more than 90% over a wide wavelength range from 1450 to 1650 nm for both TE and TM polarized modes.

  17. Broadband IR polarizing beam splitter using a subwavelength-structured one-dimensional photonic-crystal layer embedded in a high-index prism.

    Science.gov (United States)

    Khanfar, H K; Azzam, R M A

    2009-09-20

    An iterative procedure for the design of a polarizing beam splitter (PBS) that uses a form-birefringent, subwavelength-structured, one-dimensional photonic-crystal layer (SWS 1-D PCL) embedded in a high-index cubical prism is presented. The PBS is based on index matching and total transmission for the p polarization and total internal reflection for the s polarization at the prism-PCL interface at 45 degrees angle of incidence. A high extinction ratio in reflection (>50 dB) over the 4-12 microm IR spectral range is achieved using a SWS 1-D PCL of ZnTe embedded in a ZnS cube within an external field of view of +/-6.6 degrees and in the presence of grating filling factor errors of up to +/-10%. Comparable results, but with wider field of view, are also obtained with a Ge PCL embedded in a Si prism.

  18. High-precision broad-band linear polarimetry of early-type binaries. II. Variable, phase-locked polarization in triple Algol-type system λ Tauri

    Science.gov (United States)

    Berdyugin, A.; Piirola, V.; Sakanoi, T.; Kagitani, M.; Yoneda, M.

    2018-03-01

    Aim. To study the binary geometry of the classic Algol-type triple system λ Tau, we have searched for polarization variations over the orbital cycle of the inner semi-detached binary, arising from light scattering in the circumstellar material formed from ongoing mass transfer. Phase-locked polarization curves provide an independent estimate for the inclination i, orientation Ω, and the direction of the rotation for the inner orbit. Methods: Linear polarization measurements of λ Tau in the B, V , and R passbands with the high-precision Dipol-2 polarimeter have been carried out. The data have been obtained on the 60 cm KVA (Observatory Roque de los Muchachos, La Palma, Spain) and Tohoku 60 cm (Haleakala, Hawaii, USA) remotely controlled telescopes over 69 observing nights. Analytic and numerical modelling codes are used to interpret the data. Results: Optical polarimetry revealed small intrinsic polarization in λ Tau with 0.05% peak-to-peak variation over the orbital period of 3.95 d. The variability pattern is typical for binary systems showing strong second harmonic of the orbital period. We apply a standard analytical method and our own light scattering models to derive parameters of the inner binary orbit from the fit to the observed variability of the normalized Stokes parameters. From the analytical method, the average for three passband values of orbit inclination i = 76° + 1°/-2° and orientation Ω = 15°(195°) ± 2° are obtained. Scattering models give similar inclination values i = 72-76° and orbit orientation ranging from Ω = 16°(196°) to Ω = 19°(199°), depending on the geometry of the scattering cloud. The rotation of the inner system, as seen on the plane of the sky, is clockwise. We have found that with the scattering model the best fit is obtained for the scattering cloud located between the primary and the secondary, near the inner Lagrangian point or along the Roche lobe surface of the secondary facing the primary. The inclination i

  19. Broadband measurements of electron cyclotron emission in TFTR [Tokamak Fusion Test Reactor] using a quasi-optical light collection system and a polarizing Michelson interferometer

    International Nuclear Information System (INIS)

    Stauffer, F.J.; Boyd, D.A.; Cutler, R.C.; Diesso, M.; McCarthy, M.P.; Montague, J.; Rocco, R.

    1988-04-01

    For the past three years, a Fourier transform spectrometer diagnostic system, employing a fast-scanning polarizing Michelson interferometer, has been operating on the TFTR tokamak at Princeton Plasma Physics Laboratory. It is used to measure the electron cyclotron emission spectrum over the range 2.5 to 18 cm/sup /minus/1/ (75-540 GHz) with a resolution of 0.123 cm/sup /minus/1/(3.7 GHz), at a rate of 72 spectra per second. The quasi-optical system for collecting the light and transporting it through the interferometer to the detector has been designed using the concepts of both Gaussian and geometrical optics in order to produce a system that is efficient over the entire spectral range. The commerical Michelson interferometer was custom-made for this project and is at the state of the art for this type of specialized instrument. Various pre-installation and post-installation tests of the optical system and the interferometer were performed and are reported here. An error propagation analysis of the absolute calibration process is given. Examples of electron cyclotron emission spectra measured in two polarization directions are given, and electron temperature profiles derived from each of them are compared. 34 refs., 17 figs

  20. Low-Cost and High-Gain SIW Circularly Polarized Circular-Horn-Loaded Antenna for Broadband Millimeter-Wave Applications

    Directory of Open Access Journals (Sweden)

    Ming Du

    2017-09-01

    Full Text Available A wideband, low-cost and high-gain circularly polarized (CP circular-horn-loaded antenna based on substrate integrated waveguide (SIW technology operating at Ka band is presented. The proposed antenna, which is built on a single-layer substrate, consists of five parts: a short-ended SIW, a centro-symmetric wide slot, an L-shaped probe, a circular horn and a transition from SIW to air-filled rectangular waveguide for measurement. The slot is etched on the upper ground of the SIW, while the L-shaped probe for generating CP wave is printed inside the slot and connected to the SIW. A circular horn is also loaded on the surface of the SIW slot for high gain. Then, the proposed antenna with a dimension of 45×45×24.16 mm3 was fabricated and measured. The measured results show that the antenna has a wide impedance matching bandwidth of 28.6% from 30 to 40 GHz for |S11| ≤10 dB and a wide axial ratio (AR bandwidth of 22.8% from 31.5 to 39.6 GHz for AR ≤ 3 dB. The measured maximum gain is 15.6 dBi at 36 GHz with slight fluctuations over the 30–40-GHz frequency range. This kind of antenna merits low cost and easy integration with common differential circuits at the same time.

  1. Polarization and emission geometry of the Crab pulsar

    International Nuclear Information System (INIS)

    Kaiyou Chen; Cheng Ho

    1993-01-01

    Optical emission of the Crab pulsar can best be understood as synchrotron radiation of relativistic particles from the outer magnetosphere of the neutron star. The outer gap model was developed specifically to address energy balance and double-pulsed emission (from optical to high-energy gamma-ray) of young pulsars like the Crab. In this paper, we present the polarization properties of the optical pulses calculated from the outer gap model. We found that the theoretical light curves exhibit the same qualitative behavior as observations

  2. Broadband Radiometric LED Measurements

    OpenAIRE

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2016-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(��) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irr...

  3. Broadband Faraday isolator.

    Science.gov (United States)

    Berent, Michał; Rangelov, Andon A; Vitanov, Nikolay V

    2013-01-01

    Driving on an analogy with the technique of composite pulses in quantum physics, we theoretically propose a broadband Faraday rotator and thus a broadband optical isolator, which is composed of sequences of ordinary Faraday rotators and achromatic quarter-wave plates rotated at the predetermined angles.

  4. Broadband Circularly Polarized Patch Antenna and Method

    Science.gov (United States)

    2016-09-16

    February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...thereon or therefor. CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0002] None. BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The

  5. Broadband Electromagnetic Technology

    Science.gov (United States)

    2011-06-23

    The objectives of this project are to continue the enhancements to the combined Broadband Electromagnetic and Full Encirclement Unit (BEM-FEU) technologies and to evaluate the systems capability in the laboratory and the field. The BEM instrument ...

  6. Broadband radiometric LED measurements

    Science.gov (United States)

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2016-09-01

    At present, broadband radiometric LED measurements with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  7. Direct UV-written broadband directional broadband planar waveguide couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    2005-01-01

    We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation.......We report the fabrication of broadband directional couplers by direct UV-writing. The fabrication process is shown to be beneficial, robust and flexible. The components are compact and show superior performance in terms of loss and broadband operation....

  8. Broadband Internet and Income Inequality

    OpenAIRE

    HOUNGBONON , Georges Vivien; Liang , Julienne

    2017-01-01

    Policy makers are aiming for a large coverage of high-speed broadband Internet. However , there is still a lack of evidence about its effects on income distribution. In this paper, we investigate the effects of fixed broadband Internet on mean income and income inequality using a unique town-level data on broadband adoption and quality in France. We find that broadband adoption and quality raise mean income and lower income inequality. These results are robust to initial conditions, and yield...

  9. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  10. Broadband waveguided light sources

    NARCIS (Netherlands)

    Pollnau, Markus

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The

  11. Advanced broadband baffle materials

    International Nuclear Information System (INIS)

    Seals, R.D.

    1991-01-01

    In this paper broadband performance characteristics of robust, light-weight, diffuse-absorptive baffle surfaces fabricated from sputter-deposited beryllium on cross-rolled Be ingot sheet material and on Be foam, plasma sprayed beryllium, plasma sprayed boron-on-beryllium, and chemical vapor deposited boron carbide on graphite are described and compared to Martin Black. An overview of the Optics Manufacturing Operations Development and Integration Laboratory (MODIL) Advanced Optical Baffle Program will be discussed

  12. Broadband electromagnetic environments simulator (EMES)

    International Nuclear Information System (INIS)

    Pollard, N.

    1977-01-01

    A new test facility has been developed by Sandia Laboratories for determining the effects of electromagnetic environments on systems and components. The facility is capable of producing uniform, vertically polarized, continuous wave (CW) and pulsed fields over the frequency range of dc to 10 GHz. This broadband capability addresses the electromagnetic radiation (EMR) threat and is ideally suited to computer controlled sweeping and data acquisition. EMES is also capable of producing uniform transient fields having the wave shape and magnitude characteristic of a nuclear electromagnetic pulse (EMP) and near lightning. The design consists of a truncated, triplate, rectangular coaxial transmission line. The spacing between the flat center conductor and the ground planes is 4 meters. The line is terminated in its characteristic impedance of 50 ohms. At frequencies below the first resonance of the facility it behaves as a typical coaxial system. Above resonance, a wall of electromagnetic absorbing material provides a nonreflecting termination. Thus, EMES essentially combines the elements of a transmission line and an anechoic chamber. It will not radiate electromagnetic energy into the surrounding area because it is a shielded transmission line

  13. Broadband Radio Service (BRS) and Educational Broadband Service (EBS) Transmitters

    Data.gov (United States)

    Department of Homeland Security — The Broadband Radio Service (BRS), formerly known as the Multipoint Distribution Service (MDS)/Multichannel Multipoint Distribution Service (MMDS), is a commercial...

  14. AIRTV: Broadband Direct to Aircraft

    Science.gov (United States)

    Sorbello, R.; Stone, R.; Bennett, S. B.; Bertenyi, E.

    2002-01-01

    over the poles. The system consists of a constellation of 4 geostationary satellites covering the earth and delivering its signals to the aircraft at S band (2.52 -2.67 GHz). The S-band spectrum is ideal for this application since it is allocated on a primary basis by the ITU for global broadcast service. The AirTV service is expected to begin in 2004 and should be unencumbered by adjacent satellite interference due to near completion of the ITU coordination process. Each satellite will deliver four 20 Mbps QPSK data streams consisting of multiplexed compressed digital video channels and IP data over the full global beam coverage. The 80 Mbps capacity of each satellite will provide approximately 60 video channels while still allocating 40 Mbits to data services. The combined constellation capacity of 320 Mbits will significantly exceed the capacity of any similar existing or currently planned global satellite system. In addition, the simplicity of the 4-satellite approach is the most cost effective means to deliver high bandwidth globally. Return links, which are required for internet service, will be provided through the existing Inmarsat Aero-H system already onboard virtually all long haul aircraft and will provide return data rates from the aircraft as high as 432 kbps. integrated receiver/decoder (IRD) assembly. The phased array antenna, a key technology element, is being developed by AirTV's strategic partner, CMC Electronics. This antenna is a scaled version of CMC's Inmarsat Aero H antenna and is capable of scanning to 5 degrees above the horizon. Wide angle scanning up to 85 degrees from zenith is necessary for aircraft traversing the northernmost latitudes on transoceanic routes. AirTV has designed both the satellite coverage and aircraft antenna performance to ensure that high signal quality is maintained along all non-polar airline routes. AirTV will be the future of aeronautical broadband delivery. It has been designed specifically for global services and

  15. Handheld Broadband Electromagnetic UXO Sensor

    National Research Council Canada - National Science Library

    Won, I. J; San Filipo, William A; Marqusee, Jeffrey; Andrews, Anne; Robitaille, George; Fairbanks, Jeffrey; Overbay, Larry

    2005-01-01

    The broadband electromagnetic sensor improvement and demonstration undertaken in this project took the prototype GEM-3 and evolved it into an operational sensor with increased bandwidth and dynamic...

  16. Broadband chirality and asymmetric transmission in ultrathin 90°-twisted Babinet-inverted metasurfaces

    Science.gov (United States)

    Shi, J. H.; Ma, H. F.; Guan, C. Y.; Wang, Z. P.; Cui, T. J.

    2014-04-01

    A broadband asymmetric transmission of linearly polarized waves with totally suppressed copolarization transmission is experimentally demonstrated in ultrathin 90°-twisted Babinet-inverted metasurfaces constructed by an array of asymmetrically split ring apertures. The only accessible direction-dependent cross-polarization transmission is allowed in this anisotropic chiral metamaterial. Through full-wave simulation and experiment results, the bilayered Babinet-inverted metasurface reveals broadband artificial chirality and asymmetric transmission, with a transmission contrast that is better than 17.7 dB within a 50% relative bandwidth for two opposite directions. In particular, we can modify polarization conversion efficiency and the bandwidth of asymmetric transmission via parametric study.

  17. An Assessment of Emerging Wireless Broadband Technologies

    National Research Council Canada - National Science Library

    Fountanas, Leonidas

    2001-01-01

    ... technologies in providing broadband services today, emerging wireless broadband technologies are expected to significantly increase their market share over the next years, Deploying a wireless network...

  18. Interferometric polarization control

    International Nuclear Information System (INIS)

    Chuss, David T.; Wollack, Edward J.; Moseley, S. Harvey; Novak, Giles

    2006-01-01

    We develop the Jones and Mueller matrices for structures that allow control of the path length difference between two linear orthogonal polarizations and consider the effect of placing multiple devices in series. Specifically, we find that full polarization modulation (measurement of Stokes Q, U, and V) can be achieved by placing two such modulators in series if the relative angles of the beam-splitting grids with respect to the analyzer orientation are appropriately chosen. Such a device has several potential advantages over a spinning wave plate modulator for measuring astronomical polarization in the far infrared through millimeter: (i) The use of small, linear motions eliminates the need for cryogenic rotational bearings; (ii) the phase flexibility allows measurement of circular as well as linear polarization; and (iii) this architecture allows for both multiwavelength and broadband modulation. We also present initial laboratory results

  19. Broadband unidirectional ultrasound propagation

    Science.gov (United States)

    Sinha, Dipen N.; Pantea, Cristian

    2017-12-12

    A passive, linear arrangement of a sonic crystal-based apparatus and method including a 1D sonic crystal, a nonlinear medium, and an acoustic low-pass filter, for permitting unidirectional broadband ultrasound propagation as a collimated beam for underwater, air or other fluid communication, are described. The signal to be transmitted is first used to modulate a high-frequency ultrasonic carrier wave which is directed into the sonic crystal side of the apparatus. The apparatus processes the modulated signal, whereby the original low-frequency signal exits the apparatus as a collimated beam on the side of the apparatus opposite the sonic crystal. The sonic crystal provides a bandpass acoustic filter through which the modulated high-frequency ultrasonic signal passes, and the nonlinear medium demodulates the modulated signal and recovers the low-frequency sound beam. The low-pass filter removes remaining high-frequency components, and contributes to the unidirectional property of the apparatus.

  20. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities

    KAUST Repository

    Zhang, Xueqian; Tian, Zhen; Yue, Weisheng; Gu, Jianqiang; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2013-01-01

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Broadband terahertz wave deflection based on C-shape complex metamaterials with phase discontinuities

    KAUST Repository

    Zhang, Xueqian

    2013-06-21

    A broadband terahertz wave deflector based on metasurface induced phase discontinuities is reported. Various frequency components ranging from 0.43 to 1.0 THz with polarization orthogonal to the incidence are deflected into a broad range of angles from 25° to 84°. A Fresnel zone plate consequently developed from the beam deflector is capable of focusing a broadband terahertz radiation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Compact U-Slotted Antenna for Broadband Radar Applications

    Directory of Open Access Journals (Sweden)

    S. Costanzo

    2013-01-01

    Full Text Available The original U-shaped patch antenna is properly modified in this work to provide a compact and broadband antenna configuration with reduced cross-polar effects, well suitable for modern radar applications. The proposed antenna layout is applied to design, realize, and test two different prototypes working at P-band and C-band, typically adopted for ground-penetrating radar. The experimental results successfully demonstrate a large operating bandwidth between 15% and 20%, a significant reduction of size (about half of the standard configuration, and a low cross-polarization level within the operating frequency range.

  3. Broadband accelerator control network

    International Nuclear Information System (INIS)

    Skelly, J.; Clifford, T.; Frankel, R.

    1983-01-01

    A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AG) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating system has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel

  4. Manipulating the strength and broadband of the resonators in the terahertz metamaterials

    Science.gov (United States)

    Liu, Changxiang; Zhou, Qingli; Li, Chenyu; Zhang, Cunlin

    2018-01-01

    We investigate two dipoles which are attached or separated with the orthogonal arrangement in the terahertz frequency. These results show that the metasurface could achieve the resonance coupling and polarization conversion effect. There are two resonance dips in the transmission spectra, when these two dipoles are attached to form the L-shaped structure. With the spacing between vertical and horizontal dipoles separated, the broadband of the resonator becomes narrower and resonance dips merge into one deeper dip due to the superposition of the interaction of two dipoles. The loss of the energy is not only coupled to the free space but also converted to the cross-polarization. The broadband and the strength of the crosspolarization are modulated by changing the distance between the vertical and horizontal dipoles. Tuning the spacing, we control the co- and cross polarization of the broadband and the strength at the same time. This modulation provides the functionally potential applications in the terahertz modulators and filters.

  5. Broadband Rotational Spectroscopy

    Science.gov (United States)

    Pate, Brooks

    2014-06-01

    The past decade has seen several major technology advances in electronics operating at microwave frequencies making it possible to develop a new generation of spectrometers for molecular rotational spectroscopy. High-speed digital electronics, both arbitrary waveform generators and digitizers, continue on a Moore's Law-like development cycle that started around 1993 with device bandwidth doubling about every 36 months. These enabling technologies were the key to designing chirped-pulse Fourier transform microwave (CP-FTMW) spectrometers which offer significant sensitivity enhancements for broadband spectrum acquisition in molecular rotational spectroscopy. A special feature of the chirped-pulse spectrometer design is that it is easily implemented at low frequency (below 8 GHz) where Balle-Flygare type spectrometers with Fabry-Perot cavity designs become technologically challenging due to the mirror size requirements. The capabilities of CP-FTMW spectrometers for studies of molecular structure will be illustrated by the collaborative research effort we have been a part of to determine the structures of water clusters - a project which has identified clusters up to the pentadecamer. A second technology trend that impacts molecular rotational spectroscopy is the development of high power, solid state sources in the mm-wave/THz regions. Results from the field of mm-wave chirped-pulse Fourier transform spectroscopy will be described with an emphasis on new problems in chemical dynamics and analytical chemistry that these methods can tackle. The third (and potentially most important) technological trend is the reduction of microwave components to chip level using monolithic microwave integrated circuits (MMIC) - a technology driven by an enormous mass market in communications. Some recent advances in rotational spectrometer designs that incorporate low-cost components will be highlighted. The challenge to the high-resolution spectroscopy community - as posed by Frank De

  6. Driving demand for broadband networks and services

    CERN Document Server

    Katz, Raul L

    2014-01-01

    This book examines the reasons why various groups around the world choose not to adopt broadband services and evaluates strategies to stimulate the demand that will lead to increased broadband use. It introduces readers to the benefits of higher adoption rates while examining the progress that developed and emerging countries have made in stimulating broadband demand. By relying on concepts such as a supply and demand gap, broadband price elasticity, and demand promotion, this book explains differences between the fixed and mobile broadband demand gap, introducing the notions of substitution and complementarity between both platforms. Building on these concepts, ‘Driving Demand for Broadband Networks and Services’ offers a set of best practices and recommendations aimed at promoting broadband demand.  The broadband demand gap is defined as individuals and households that could buy a broadband subscription because they live in areas served by telecommunications carriers but do not do so because of either ...

  7. Linearization Technologies for Broadband Radio-Over-Fiber Transmission Systems

    Directory of Open Access Journals (Sweden)

    Xiupu Zhang

    2014-11-01

    Full Text Available Linearization technologies that can be used for linearizing RoF transmission are reviewed. Three main linearization methods, i.e. electrical analog linearization, optical linearization, and electrical digital linearization are presented and compared. Analog linearization can be achieved using analog predistortion circuits, and can be used for suppression of odd order nonlinear distortion components, such as third and fifth order. Optical linearization includes mixed-polarization, dual-wavelength, optical channelization and the others, implemented in optical domain, to suppress both even and odd order nonlinear distortion components, such as second and third order. Digital predistortion has been a widely used linearization method for RF power amplifiers. However, digital linearization that requires analog to digital converter is severely limited to hundreds of MHz bandwidth. Instead, analog and optical linearization provide broadband linearization with up to tens of GHz. Therefore, for broadband radio over fiber transmission that can be used for future broadband cloud radio access networks, analog and optical linearization are more appropriate than digital linearization. Generally speaking, both analog and optical linearization are able to improve spur-free dynamic range greater than 10 dB over tens of GHz. In order for current digital linearization to be used for broadband radio over fiber transmission, the reduced linearization complexity and increased linearization bandwidth are required. Moreover, some digital linearization methods in which the complexity can be reduced, such as Hammerstein type, may be more promising and require further investigation.

  8. Femtosecond Broadband Stimulated Raman Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Soo-Y; Yoon, Sagwoon; Mathies, Richard A

    2006-01-01

    Femtosecond broadband stimulated Raman spectroscopy (FSRS) is a new technique where a narrow bandwidth picosecond Raman pump pulse and a red-shifted broadband femtosecond Stokes probe pulse (with or without time delay between the pulses) act on a sample to produce a high resolution Raman gain spectrum with high efficiency and speed, free from fluorescence background interference. It can reveal vibrational structural information and dynamics of stationary or transient states. Here, the quantum picture for femtosecond broadband stimulated Raman spectroscopy (FSRS) is used to develop the semiclassical coupled wave theory of the phenomenon and to derive an expression for the measurable Raman gain in FSRS. The semiclassical theory is applied to study the dependence of lineshapes in FSRS on the pump-probe time delay and to deduce vibrational dephasing times in cyclohexane in the ground state

  9. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J S [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  10. Observations involving broadband impedance modelling

    International Nuclear Information System (INIS)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances

  11. Polarized neutrons

    International Nuclear Information System (INIS)

    Williams, W.G.

    1988-01-01

    The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

  12. Towards helium-3 neutron polarizers

    International Nuclear Information System (INIS)

    Tasset, F.

    1995-01-01

    With a large absorption cross-section entirely due to antiparallel spin capture, polarized helium-3 is presently the most promising broad-band polarizer for thermal and epithermal neutrons. Immediate interest was raised amongst the neutron community when a dense gaseous 3 He polarizer was used for the first time in 1988, on a pulsed neutron beam at Los Alamos. With 20 W of laser power on a 30 cm long, 8.6 atm target, 40% 3 He polarization was achieved in a recent polarized electron scattering experiment at SLAC. In this technique the 3 He nuclei are polarized directly at an appropriate high pressure through spin-exchange collisions with a thick, optically pumped rubidium vapor. A different and competitive approach is being presently developed at Mainz University in collaboration with ENS Paris and now the ILL. A discharge is established in pure 3 He at low pressure producing excited metastable atoms which can be optically pumped with infra-red light. Highly effective exchange collision with the atoms remaining in the ground state quickly produces 75% polarization at 1.5 mbar. A truly non-magnetic system then compresses the polarized gas up to several bars as required. The most recent machine comprises a two-stage glass-titanium compressor. In less than 1 h it can inflate a 100 cm 3 target cell with three bars of polarized gas. The very long relaxation times (several days) now being obtained at high pressure with a special metallic coating on the glass walls, the polarized cell can be detached and inserted in the neutron beam as polarizer. We expect 50% 3 He-polarization to be reached soon, allowing such filters to compete favorably with existing Heusler-crystal polarizers at thermal and short neutron wavelengths. It must be stressed that such a system based on a 3 He polarization factory able to feed several passive, transportable, polarizers is well matched to neutron scattering needs. (orig.)

  13. Polarization recovery through scattering media.

    Science.gov (United States)

    de Aguiar, Hilton B; Gigan, Sylvain; Brasselet, Sophie

    2017-09-01

    The control and use of light polarization in optical sciences and engineering are widespread. Despite remarkable developments in polarization-resolved imaging for life sciences, their transposition to strongly scattering media is currently not possible, because of the inherent depolarization effects arising from multiple scattering. We show an unprecedented phenomenon that opens new possibilities for polarization-resolved microscopy in strongly scattering media: polarization recovery via broadband wavefront shaping. We demonstrate focusing and recovery of the original injected polarization state without using any polarizing optics at the detection. To enable molecular-level structural imaging, an arbitrary rotation of the input polarization does not degrade the quality of the focus. We further exploit the robustness of polarization recovery for structural imaging of biological tissues through scattering media. We retrieve molecular-level organization information of collagen fibers by polarization-resolved second harmonic generation, a topic of wide interest for diagnosis in biomedical optics. Ultimately, the observation of this new phenomenon paves the way for extending current polarization-based methods to strongly scattering environments.

  14. Achieving universal access to broadband

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders

    2009-01-01

    The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures...

  15. Recovering a hidden polarization by ghost polarimetry.

    Science.gov (United States)

    Janassek, Patrick; Blumenstein, Sébastien; Elsäßer, Wolfgang

    2018-02-15

    By exploiting polarization correlations of light from a broadband fiber-based amplified spontaneous emission source we succeed in reconstructing a hidden polarization in a ghost polarimetry experiment in close analogy to ghost imaging and ghost spectroscopy. Thereby, an original linear polarization state in the object arm of a Mach-Zehnder interferometer configuration which has been camouflaged by a subsequent depolarizer is recovered by correlating it with light from a reference beam. The variation of a linear polarizer placed inside the reference beam results in a Malus law type second-order intensity correlation with high contrast, thus measuring a ghost polarigram.

  16. Multilayer tungsten-alumina-based broadband light absorbers for high-temperature applications

    DEFF Research Database (Denmark)

    Chirumamilla, Manohar; Roberts, Alexander Sylvester; Ding, Fei

    2016-01-01

    Efficient broadband absorption of visible and near-infrared light by low quality-factor metal-insulator-metal (MIM) resonators using refractory materials is reported. Omnidirectional absorption of incident light for broad angles of incidence and polarization insensitivity are observed for the fab...

  17. The polarization of NGC 1068

    International Nuclear Information System (INIS)

    Bailey, Jeremy; Axon, D.J.; Hough, J.H.; Heathcote, S.R.

    1988-01-01

    Broad-band polarimetry of NGC 1068 over the wavelength range 0.36-4.8μm is presented, together with high-resolution spectropolarimetry of the Hβ, [O III] and Hα, [N II] regions of the spectrum. We recognize several different polarization components and conclude that they can all be accounted for by processes involving dust. Optical continuum polarization and broad features associated with the Balmer emission lines are due to scattering into the line of sight, of radiation from an obscured Seyfert I nucleus. We argue that the scattering is probably by dust in the narrow line region, but cannot exclude the possibility of electron scattering. (author)

  18. Broadband near-infrared metamaterial absorbers utilizing highly lossy metals

    DEFF Research Database (Denmark)

    Ding, Fei; Dai, Jin; Chen, Yiting

    2016-01-01

    Radiation absorbers have increasingly been attracting attention as crucial components for controllable thermal emission, energy harvesting, modulators, etc. However, it is still challenging to realize thin absorbers which can operate over a wide spectrum range. Here, we propose and experimentally...... demonstrate thin, broadband, polarization-insensitive and omnidirectional absorbers working in the near-infrared range. We choose titanium (Ti) instead of the commonly used gold (Au) to construct nano-disk arrays on the top of a silicon dioxide (SiO2) coated Au substrate, with the quality (Q) factor...

  19. A broadband electromagnetic UT system

    International Nuclear Information System (INIS)

    Repplinger, W.; Salzburger, H.J.

    1985-01-01

    An ultrasonic testing system based on contactless electromagnetic acoustic (E.M.A.) transduction has been developed by which broadband ultrasonic pulses are excited. This system overcomes disadvantages of usual E.M.A. transducers with meanderlike coil configuration, namely the excitation of narrowband pulses and the symmetrical radiation pattern. By dividing up a meanderlike coil into single elements and a time-delayed firing of the elements, whereby the time delay is given by the distance of the elements and the phase velocity of the wave propagating along the surface, the ultrasonic pulse radiated in one preferred direction becomes broadband by constructive interference. The signals radiated in the opposite direction do no more interfere. Its amplitude is smaller than that of the other direction, so that the transducer becomes uni-directional. This technique can be applied for the excitation of all dispersionless waves (bulk waves and guided waves)

  20. Integrated Broadband Quantum Cascade Laser

    Science.gov (United States)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  1. VIIRS-J1 Polarization Narrative

    Science.gov (United States)

    Waluschka, Eugene; McCorkel, Joel; McIntire, Jeff; Moyer, David; McAndrew, Brendan; Brown, Steven W.; Lykke, Keith; Butler, James; Meister, Gerhard; Thome, Kurtis J.

    2015-01-01

    The VIS/NIR bands polarization sensitivity of Joint Polar Satellite Sensor 1 (JPSS1) Visible/Infrared Imaging Radiometer Suite (VIIRS) instrument was measured using a broadband source. While polarization sensitivity for bands M5-M7, I1, and I2 was less than 2.5%, the maximum polarization sensitivity for bands M1, M2, M3, and M4 was measured to be 6.4%, 4.4%, 3.1%, and 4.3%, respectively with a polarization characterization uncertainty of less than 0.3%. A detailed polarization model indicated that the large polarization sensitivity observed in the M1 to M4 bands was mainly due to the large polarization sensitivity introduced at the leading and trailing edges of the newly manufactured VISNIR bandpass focal plane filters installed in front of the VISNIR detectors. This was confirmed by polarization measurements of bands M1 and M4 bands using monochromatic light. Discussed are the activities leading up to and including the instruments two polarization tests, some discussion of the polarization model and the model results, the role of the focal plane filters, the polarization testing of the Aft-Optics-Assembly, the testing of the polarizers at Goddard and NIST and the use of NIST's T-SIRCUS for polarization testing and associated analyses and results.

  2. Electronic resonances in broadband stimulated Raman spectroscopy

    Science.gov (United States)

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

  3. Analysis of the Proposed Ghana Broadband Strategy

    DEFF Research Database (Denmark)

    Williams, Idongesit; Botwe, Yvonne

    This project studied the Ghana Broadband Strategy with the aim of evaluating the recommendations in the strategy side by side the broadband development in Ghana. The researchers conducted interviews both officially and unofficially with ICT stakeholders, made observations, studied Government...... intervention policies recommended in the Ghana broadband policy is used to evaluate the broadband market to find out whether the strategy consolidates with the Strengths and opportunities of the market and whether it corrects the anomalies that necessitate the weaknesses and threats to the market....... The strategy did address some threats and weaknesses of the broadband market. It also consolidated on some strengths and opportunities of the broadband market. The researchers also discovered that a market can actually grow without a policy. But a market will grow faster if a well implemented policy is guiding...

  4. Metamaterial-based half Maxwell fish-eye lens for broadband directive emissions

    Science.gov (United States)

    Dhouibi, Abdallah; Nawaz Burokur, Shah; de Lustrac, André; Priou, Alain

    2013-01-01

    The broadband directive emission from a metamaterial surface is numerically and experimentally reported. The metasurface, composed of non-resonant complementary closed ring structures, is designed to obey the refractive index of a half Maxwell fish-eye lens. A planar microstrip Vivaldi antenna is used as transverse magnetic polarized wave launcher for the lens. A prototype of the lens associated with its feed structure has been fabricated using standard lithography techniques. To experimentally demonstrate the broadband focusing properties and directive emissions, both the far-field radiation patterns and the near-field distributions have been measured. Measurements agree quantitatively and qualitatively with theoretical simulations.

  5. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  6. Tuchola County Broadband Network (TCBN)

    DEFF Research Database (Denmark)

    Zabludowski, Antoni; Dubalski, B.; Zabludowski, Lukasz

    2012-01-01

    In the paper the designing project (plan) of Tuchola City broadband IP optical network has been presented. The extended version of network plan constitute technical part of network Feasibility Study, that it is expected to be implemented in Tuchola and be financed from European Regional Development...... Funds. The network plan presented in the paper contains both topological structure of fiber optic network as well as the active equipment for the network. In the project described in the paper it has been suggested to use Modular Cable System - MCS for passive infrastructure and Metro Ethernet...

  7. Understanding broadband over power line

    CERN Document Server

    Held, Gilbert

    2006-01-01

    Understanding Broadband over Power Line explores all aspects of the emerging technology that enables electric utilities to provide support for high-speed data communications via their power infrastructure. This book examines the two methods used to connect consumers and businesses to the Internet through the utility infrastructure: the existing electrical wiring of a home or office; and a wireless local area network (WLAN) access point.Written in a practical style that can be understood by network engineers and non-technologists alike, this volume offers tutorials on electric utility infrastru

  8. Achieving Universal Access to Broadband

    Directory of Open Access Journals (Sweden)

    Morten FALCH

    2009-01-01

    Full Text Available The paper discusses appropriate policy measures for achieving universal access to broadband services in Europe. Access can be delivered by means of many different technology solutions described in the paper. This means a greater degree of competition and affects the kind of policy measures to be applied. The paper concludes that other policy measure than the classical universal service obligation are in play, and discusses various policy measures taking the Lisbon process as a point of departure. Available policy measures listed in the paper include, universal service obligation, harmonization, demand stimulation, public support for extending the infrastructure, public private partnerships (PPP, and others.

  9. Coherent active polarization control without loss

    Science.gov (United States)

    Ye, Yuqian; Hay, Darrick; Shi, Zhimin

    2017-11-01

    We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

  10. Coherent active polarization control without loss

    Directory of Open Access Journals (Sweden)

    Yuqian Ye

    2017-11-01

    Full Text Available We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

  11. Broadband Wireline Provider Service Summary; BBRI_wirelineSum12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of broadband Internet access in Rhode Island via all wireline technologies assessed by Broadband Rhode Island. Broadband...

  12. Broadband and high-efficiency vortex beam generator based on a hybrid helix array.

    Science.gov (United States)

    Fang, Chaoqun; Wu, Chao; Gong, Zhijie; Zhao, Song; Sun, Anqi; Wei, Zeyong; Li, Hongqiang

    2018-04-01

    The vortex beam which carries the orbital angular momentum has versatile applications, such as high-resolution imaging, optical communications, and particle manipulation. Generating vortex beams with the Pancharatnam-Berry (PB) phase has drawn considerable attention for its unique spin-to-orbital conversion features. Despite the PB phase being frequency independent, an optical element with broadband high-efficiency circular polarization conversion feature is still needed for the broadband high-efficiency vortex beam generation. In this work, a broadband and high-efficiency vortex beam generator based on the PB phase is built with a hybrid helix array. Such devices can generate vortex beams with arbitrary topological charge. Moreover, vortex beams with opposite topological charge can be generated with an opposite handedness incident beam that propagates backward. The measured efficiency of our device is above 65% for a wide frequency range, with the relative bandwidth of 46.5%.

  13. 75 FR 10464 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-03-08

    ... window for Public Computer Center (PCC) and Sustainable Broadband Adoption (SBA) projects. DATES: All...; Extension of Application Closing Deadline for Comprehensive Community Infrastructure (CCI) Projects. SUMMARY... Infrastructure (CCI) projects under the Broadband Technology Opportunities Program (BTOP) is extended until 5:00...

  14. Broadband for all closing the infrastructure gap

    CSIR Research Space (South Africa)

    Roux, K

    2015-10-01

    Full Text Available than just addressing the infrastructure issue. The CSIR is mapping the country’s broadband infrastructure to understand where the largest gaps are, is developing models for how those gaps in broadband infrastructure can be closed. In this presentation...

  15. Customer Churn Prediction for Broadband Internet Services

    Science.gov (United States)

    Huang, B. Q.; Kechadi, M.-T.; Buckley, B.

    Although churn prediction has been an area of research in the voice branch of telecommunications services, more focused studies on the huge growth area of Broadband Internet services are limited. Therefore, this paper presents a new set of features for broadband Internet customer churn prediction, based on Henley segments, the broadband usage, dial types, the spend of dial-up, line-information, bill and payment information, account information. Then the four prediction techniques (Logistic Regressions, Decision Trees, Multilayer Perceptron Neural Networks and Support Vector Machines) are applied in customer churn, based on the new features. Finally, the evaluation of new features and a comparative analysis of the predictors are made for broadband customer churn prediction. The experimental results show that the new features with these four modelling techniques are efficient for customer churn prediction in the broadband service field.

  16. Mapping Surface Broadband Albedo from Satellite Observations: A Review of Literatures on Algorithms and Products

    Directory of Open Access Journals (Sweden)

    Ying Qu

    2015-01-01

    Full Text Available Surface albedo is one of the key controlling geophysical parameters in the surface energy budget studies, and its temporal and spatial variation is closely related to the global climate change and regional weather system due to the albedo feedback mechanism. As an efficient tool for monitoring the surfaces of the Earth, remote sensing is widely used for deriving long-term surface broadband albedo with various geostationary and polar-orbit satellite platforms in recent decades. Moreover, the algorithms for estimating surface broadband albedo from satellite observations, including narrow-to-broadband conversions, bidirectional reflectance distribution function (BRDF angular modeling, direct-estimation algorithm and the algorithms for estimating albedo from geostationary satellite data, are developed and improved. In this paper, we present a comprehensive literature review on algorithms and products for mapping surface broadband albedo with satellite observations and provide a discussion of different algorithms and products in a historical perspective based on citation analysis of the published literature. This paper shows that the observation technologies and accuracy requirement of applications are important, and long-term, global fully-covered (including land, ocean, and sea-ice surfaces, gap-free, surface broadband albedo products with higher spatial and temporal resolution are required for climate change, surface energy budget, and hydrological studies.

  17. Cylinder and metal grating polarization beam splitter

    Science.gov (United States)

    Yang, Junbo; Xu, Suzhi

    2017-08-01

    We propose a novel and compact metal grating polarization beam splitter (PBS) based on its different reflected and transmitted orders. The metal grating exhibits a broadband high reflectivity and polarization dependence. The rigorous coupled wave analysis is used to calculate the reflectivity and the transmitting spectra and optimize the structure parameters to realize the broadband PBS. The finite-element method is used to calculate the field distribution. The characteristics of the broadband high reflectivity, transmitting and the polarization dependence are investigated including wavelength, period, refractive index and the radius of circle grating. When grating period d = 400 nm, incident wavelength λ = 441 nm, incident angle θ = 60° and radius of circle d/5, then the zeroth reflection order R0 = 0.35 and the transmission zeroth order T0 = 0.08 for TE polarization, however, T0 = 0.34 and R0 = 0.01 for TM mode. The simple fabrication method involves only single etch step and good compatibility with complementary metal oxide semiconductor technology. PBS designed here is particularly suited for optical communication and optical information processing.

  18. Emission polarization study on quartz and calcite.

    Science.gov (United States)

    Vincent, R. K.

    1972-01-01

    Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

  19. Advent of broadband public-switched communications

    Science.gov (United States)

    Casey, John J.

    1992-02-01

    Advances in data communications infrastructure, display technology, and man-machine interfaces have changed business applications and the requirements of public network data transport. These changes have created opportunities for a new generation of public broadband services to more efficiently extend high speed communications capabilities beyond the customer premises. This paper provides a view of the technology and market evolution of these public broadband data communications services, and suggests early customer networked applications that justify the deployment of a public switched broadband network infrastructure.

  20. 47 CFR 27.1305 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Shared wireless broadband network. 27.1305... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network. At...

  1. 47 CFR 90.1405 - Shared wireless broadband network.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Shared wireless broadband network. 90.1405... broadband network. The Shared Wireless Broadband Network developed by the 700 MHz Public/Private Partnership must be designed to meet requirements associated with a nationwide, public safety broadband network. At...

  2. HERA Broadband Feed Design for Low-Frequency Radio Astronomy

    Science.gov (United States)

    Garza, Sierra; Trung, Vincent; Ewall-Wice, Aaron Michael; Li, Jianshu; Hewitt, Jacqueline; Riley, Daniel; Bradley, Richard F.; Makhija, Krishna

    2018-01-01

    As part of the Hydrogen Epoch of Reionization Array (HERA) project, we are designing a broadband low-frequency radio feed to extend the bandwidth from 100-200 MHz to 50-220 MHz. By extending the lower-limit to 50 MHz, we hope to detect the signatures of the first black holes heating the hydrogen gas in the intergalactic medium.The isolation of a very faint signal from vastly brighter foregrounds sets strict requirements on antenna spectral smoothness, polarization purity, forward gain, and internal reflections. We are currently working to meet these requirements with a broad-band sinuous antenna feed suspended over the 14-m parabolic HERA dish, using a combination of measurements and simulations to verify the performance of our design.A sinuous feed has been designed and simulated with Computer Simulation Technology (CST) software. We will present the construction of a prototype sinuous antenna and measurements of its reflection coefficient, S11, including laboratory characterization of baluns. Our measurements agree well with the CST simulations of the antenna’s performance, giving us confidence in our ability to model the feed and ensure that it meets the requirements of a 21cm cosmology measurement.

  3. Analysis of United States' Broadband Policy

    National Research Council Canada - National Science Library

    Uzarski, Joel S

    2007-01-01

    .... With every month that passes, the United States fails to close the gap in the digital divide both inside its borders as well as among the other countries that lead the world in broadband penetration...

  4. Energy efficiency in future wireless broadband networks

    CSIR Research Space (South Africa)

    Masonta, MT

    2012-10-01

    Full Text Available greener economy and environment. In this research, we investigate the concept of green radio communications in wireless networks and discuss approaches for energy efficient solutions in wireless broadband network deployments. These solutions include...

  5. Analyzing Broadband Divide in the Farming Sector

    DEFF Research Database (Denmark)

    Jensen, Michael; Gutierrez Lopez, Jose Manuel; Pedersen, Jens Myrup

    2013-01-01

    , upstream and downstream connection. The main constraint is that farms are naturally located in rural areas where the required access broadband data rates are not available. This paper studies the broadband divide in relation to the Danish agricultural sector. Results show how there is an important......Agriculture industry has been evolving for centuries. Currently, the technological development of Internet oriented farming tools allows to increase the productivity and efficiency of this sector. Many of the already available tools and applications require high bandwidth in both directions...... difference between the broadband availability for farms and the rest of the households/buildings the country. This divide may be slowing down the potential technological development of the farming industry, in order to keep their competitiveness in the market. Therefore, broadband development in rural areas...

  6. Catalyzing Broadband Internet in Africa | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    ... generates a 1.4% increase in gross domestic product (GDP) in low-income countries. ... Africa offers a good example of the potential benefits and challenges of ... the policy challenges related to providing affordable broadband services; ...

  7. Nanophotonic Design for Broadband Light Management

    Energy Technology Data Exchange (ETDEWEB)

    Kosten, Emily; Callahan, Dennis; Horowitz, Kelsey; Pala, Ragip; Atwater, Harry

    2014-10-13

    We describe nanophotonic design approaches for broadband light management including i) crossed-trapezoidal Si structures ii) Si photonic crystal superlattices, and iii) tapered and inhomogeneous diameter III-V/Si nanowire arrays.

  8. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon

  9. Wireless Broadband Access and Accounting Schemes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, we propose two wireless broadband access and accounting schemes. In both schemes, the accounting system adopts RADIUS protocol, but the access system adopts SSH and SSL protocols respectively.

  10. Broadband and Unbundling Regulations in OECD Countries

    OpenAIRE

    Wallsten, Scott

    2006-01-01

    Broadband penetration and available speeds vary widely across OECD countries. Policymakers around the world, and especially in countries like the U.S. that lag in the rankings, are searching for policies to narrow those gaps. Relatively little empirical work tests possible reasons for these differences. In this paper I test the impacts of regulations and demographics on broadband development in a panel dataset across countries. In addition to adding to the meager empirical literature on broad...

  11. Polarization developments

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist

  12. A reflective-backing-free metamaterial absorber with broadband response

    Directory of Open Access Journals (Sweden)

    Cuilian Xu

    2017-06-01

    Full Text Available In this paper, we propose a polarization-independent and broadband perfect infrared (IR metamaterial absorber (MA without reflective backing. The proposed absorber is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones which can absorb 80% EM wave from 50.70 to 81.87THz, while transmit 80% EM wave from 0 to 37.71THz. With the decreasing of frequency, the transmissivity increases, which is close to 100% from 0 to 5THz. We can broaden the absorption bandwidth of the MA by cascading multi-layers truncated cones. Furthermore, the proposed IR MA promises to be one desirable stealth material for radar-IR compatibility.

  13. A multievent study of broadband electrons observed by the DMSP satellites and their relation to red aurora observed at midlatitude stations

    International Nuclear Information System (INIS)

    Shiokawa, K.; Meng, C.; Reeves, G.D.; Rich, F.J.; Yumoto, K.

    1997-01-01

    Broadband electrons during magnetic storms are characterized by an unusually intense flux of precipitating electrons in the broadband energy range from 30 eV to 30 keV near the equatorward edge of the auroral oval (47 degree endash 66 degree magnetic latitude). Broadband electrons were first reported by Shiokawa et al. [1996]. In this paper, we report a multievent study of broadband electrons, using particle data obtained by the Defense Meteorological Satellite Program (DMSP) satellites during 23 magnetic storms from January 1989 through May 1992. Twelve broadband electron events are identified. Most of them are observed in the night sector, but some are observed in the morning sector. Particle data for successive polar passes of the DMSP multisatellites are used to show that broadband electrons generally last for less than 30 min and that for some events, they precipitate over a wide range of local times simultaneously. On the basis of a quantitative calculation of optical emissions from electrons in the neutral atmosphere, we conclude that broadband electrons are a possible cause of red auroras observed at midlatitude ground stations. We suggest that broadband electrons are associated with certain substorms during the main phase of magnetic storms. This conjecture comes from observations of H component positive bays and Pi 2 pulsations observed at low-latitude magnetic stations and from magnetic field variations observed at geosynchronous satellites. We conclude that the magnetospheric source of broadband electrons lies within the inner part of the plasma sheet. This conclusion is based on the facts that broadband electrons appear in latitudes where plasma sheet particles were observed before the event and that broadband electrons are observed poleward of the subauroral ion drifts, a position that corresponds to the inner edge of the injected particle layer during storms. (Abstract Truncated)

  14. Broadband direct RF digitization receivers

    CERN Document Server

    Jamin, Olivier

    2014-01-01

    This book discusses the trade-offs involved in designing direct RF digitization receivers for the radio frequency and digital signal processing domains.  A system-level framework is developed, quantifying the relevant impairments of the signal processing chain, through a comprehensive system-level analysis.  Special focus is given to noise analysis (thermal noise, quantization noise, saturation noise, signal-dependent noise), broadband non-linear distortion analysis, including the impact of the sampling strategy (low-pass, band-pass), analysis of time-interleaved ADC channel mismatches, sampling clock purity and digital channel selection. The system-level framework described is applied to the design of a cable multi-channel RF direct digitization receiver. An optimum RF signal conditioning, and some algorithms (automatic gain control loop, RF front-end amplitude equalization control loop) are used to relax the requirements of a 2.7GHz 11-bit ADC. A two-chip implementation is presented, using BiCMOS and 65nm...

  15. A broadband accelerator control network

    International Nuclear Information System (INIS)

    Skelly, J.; Clifford, T.; Frankel, R.

    1983-01-01

    A broadband data communications network has been implemented at BNL for control of the Alternating Gradient Synchrotron (AGS) proton accelerator, using commercial CATV hardware, dual coaxial cables as the communications medium, and spanning 2.0 km. A 4 MHz bandwidth Digital Control Channel using CSMA-CA protocol is provided for digital data transmission, with 8 access nodes available over the length of the RELWAY. Each node consists of an rf modem and a microprocessor-based store-and-forward message handler which interfaces the RELWAY to a branch line implemented in GPIB. A gateway to the RELWAY control channel for the (preexisting) AGS Computerized Accelerator Operating System has been constructed using an LSI-11/23 microprocessor as a device in a GPIB branch line. A multilayer communications protocol has been defined for the Digital Control Channel, based on the ISO Open Systems Interconnect layered model, and a RELWAY Device Language defined as the required universal language for device control on this channel

  16. Ultra-broadband photonic internet

    Science.gov (United States)

    Romaniuk, Ryszard S.

    2011-06-01

    In this paper, there is presented a review of our today's understanding of the ultimately broadband photonic Internet. A simple calculation is presented showing the estimate of the throughput of the core photonic network branches. Optoelectronic components, circuits, systems and signals, together with analogous electronic entities and common software layers, are building blocks of the contemporary Internet. Participation of photonics in development of the physical layer in the future Internet will probably increase. The photonics leads now to a better usage of the available bandwidth (increase of the spectral efficiency measured in Bit/s/Hz), increase in the transmission rate (from Gbps, via Tbps up to probably Pbps), increase in the transmission distance without signal regeneration (in distortion compensated active optical cables), increase in energy/power efficiency measured in W/Gbps, etc. Photonics may lead, in the future, to fully transparent optical networks and, thus, to essential increase in bandwidth and network reliability. It is expected that photonics (with biochemistry, electronics and mechatronics) may build psychological and physiological interface for humans to the future global network. The following optical signal multiplexing methods were considered, which are possible without O/E/O conversion: TDM-OTDM, FDM-CO-OFDM, OCDM-OCDMA, WDM-DWDM.

  17. Helicity multiplexed broadband metasurface holograms.

    Science.gov (United States)

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

    2015-09-10

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

  18. Neutron polarization

    International Nuclear Information System (INIS)

    Firk, F.W.K.

    1976-01-01

    Some recent experiments involving polarized neutrons are discussed; they demonstrate how polarization studies provide information on fundamental aspects of nuclear structure that cannot be obtained from more traditional neutron studies. Until recently, neutron polarization studies tended to be limited either to very low energies or to restricted regions at higher energies, determined by the kinematics of favorable (p, vector n) and (d, vector n) reactions. With the advent of high intensity pulsed electron and proton accelerators and of beams of vector polarized deuterons, this is no longer the case. One has entered an era in which neutron polarization experiments are now being carried out, in a routine way, throughout the entire range from thermal energies to tens-of-MeV. The significance of neutron polarization studies is illustrated in discussions of a wide variety of experiments that include the measurement of T-invariance in the β-decay of polarized neutrons, a search for the effects of meson exchange currents in the photo-disintegration of the deuteron, the determination of quantum numbers of states in the fission of aligned 235 U and 237 Np induced by polarized neutrons, and the double- and triple-scattering of fast neutrons by light nuclei

  19. Broadband in schools: towards a definition and model of broadband for South African schools

    CSIR Research Space (South Africa)

    Ford, Merryl

    2017-05-01

    Full Text Available South Africa is about to provide broadband internet connectivity to all schools in the country via the implementation of the national broadband policy. The challenge is to ensure a balance between the schools’ demand-side usage and supply...

  20. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  1. Revealing the Faraday depth structure of radio galaxy NGC 612 with broad-band radio polarimetric observations

    Science.gov (United States)

    Kaczmarek, J. F.; Purcell, C. R.; Gaensler, B. M.; Sun, X.; O'Sullivan, S. P.; McClure-Griffiths, N. M.

    2018-05-01

    We present full-polarization, broad-band observations of the radio galaxy NGC 612 (PKS B0131-637) from 1.3 to 3.1 GHz using the Australia Telescope Compact Array. The relatively large angular scale of the radio galaxy makes it a good candidate with which to investigate the polarization mechanisms responsible for the observed Faraday depth structure. By fitting complex polarization models to the polarized spectrum of each pixel, we find that a single polarization component can adequately describe the observed signal for the majority of the radio galaxy. While we cannot definitively rule out internal Faraday rotation, we argue that the bulk of the Faraday rotation is taking place in a thin skin that girts the polarized emission. Using minimum energy estimates, we find an implied total magnetic field strength of 4.2 μG.

  2. Broad-band beam buncher

    International Nuclear Information System (INIS)

    Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

    1986-01-01

    This patent describes a broad-band beam buncher. This beam buncher consists of: a housing adapted to be eacuated, an electron gun in the housing for producing a beam of electrons, buncher means in the housing forming a buncher cavity which has an entrance opening for receiving the electron beam and an exit opening through which the electron beam passes out of the buncher cavity, a drift tube electrode in the buncher cavity and disposed between the entrance opening and the exit opening with first and second gaps between the drift tube electrode and the entrance and exit openings, the drift tube electrode which has a first drift space through which the electron beam passes in traveling between the entrance and exit openings, modulating means for supplying an ultrahigh frequeny modulating signal to the drift tube electrode for producing velocity modulation of the electrons in the electron beam as the electrons pass through the buncher cavity and the drift tube electrode between the entrance opening and the exit opening, drift space means in the housing forming a second drift space for receiving the velocity modulated electron beam from the exit opening, the velocity modulated electron beam being bunched as it passes along the second drift space, the drift space means has a discharge opening through which the electron beam is discharged from the second drift space after being bunched therein, the modulating means containing a signal source for producing an ultrahigh frequency signal, a transmission line connected between the signal source and the drift tube electrode, and terminating means connected to the drift tube electrode for terminating the transmission line in approximately its characteristic impedance to afford a broad response band with minimum 6 variations therein

  3. Identifying Broadband Rotational Spectra with Neural Networks

    Science.gov (United States)

    Zaleski, Daniel P.; Prozument, Kirill

    2017-06-01

    A typical broadband rotational spectrum may contain several thousand observable transitions, spanning many species. Identifying the individual spectra, particularly when the dynamic range reaches 1,000:1 or even 10,000:1, can be challenging. One approach is to apply automated fitting routines. In this approach, combinations of 3 transitions can be created to form a "triple", which allows fitting of the A, B, and C rotational constants in a Watson-type Hamiltonian. On a standard desktop computer, with a target molecule of interest, a typical AUTOFIT routine takes 2-12 hours depending on the spectral density. A new approach is to utilize machine learning to train a computer to recognize the patterns (frequency spacing and relative intensities) inherit in rotational spectra and to identify the individual spectra in a raw broadband rotational spectrum. Here, recurrent neural networks have been trained to identify different types of rotational spectra and classify them accordingly. Furthermore, early results in applying convolutional neural networks for spectral object recognition in broadband rotational spectra appear promising. Perez et al. "Broadband Fourier transform rotational spectroscopy for structure determination: The water heptamer." Chem. Phys. Lett., 2013, 571, 1-15. Seifert et al. "AUTOFIT, an Automated Fitting Tool for Broadband Rotational Spectra, and Applications to 1-Hexanal." J. Mol. Spectrosc., 2015, 312, 13-21. Bishop. "Neural networks for pattern recognition." Oxford university press, 1995.

  4. Polarization variablity among Wolf-Rayet stars. IV. A complete lack of circular polarization in the optical continuum

    International Nuclear Information System (INIS)

    Robert, C.; Moffat, A.F.J.

    1989-01-01

    Quasi-simultaneous blue and red, broadband optical monitoring in linear and circular polarization and in intensity has been carried out over an interval of three weeks for several Wolf-Rayet stars that show relatively large Delta P variations in linear polarization. No significant varying Delta V component of circular polarization is detected in any of these stars. The lower upper limit Delta V/Delta P implies that the intrinsic linearly polarized light which does vary cannot be produced by electrons gyrating in a magnetic field, unless they are ultrarelativistic - a rather unlikely situation. The low mean circular polarization typically observed is probably interstellar in origin. Lack of periodicity in the observed variations of linear polarization implies that even weak magnetic field loops are unlikely to be involved in confining pockets of wind plasma. The observed linear polarization variations are related mainly to electron scattering. 25 refs

  5. Is European Broadband Ready for Smart Grid?

    DEFF Research Database (Denmark)

    Balachandran, Kartheepan; Pedersen, Jens Myrup

    2014-01-01

    In this short paper we compare the communication requirements for three Smart Grid scenarios with the availability of broadband and mobile communication networks in Europe. We show that only in the most demanding case - where data is collected and transmitted every second - a standard GSM/GPRS co....../GPRS connection is not enough. Whereas in the less demanding scenarios it is almost all of the European households that can be covered by a standard broadband technology for use with Smart Grid.......In this short paper we compare the communication requirements for three Smart Grid scenarios with the availability of broadband and mobile communication networks in Europe. We show that only in the most demanding case - where data is collected and transmitted every second - a standard GSM...

  6. Magnetically levitated autoparametric broadband vibration energy harvesting

    International Nuclear Information System (INIS)

    Kurmann, L.; Jia, Y.; Manoli, Y.; Woias, P.

    2016-01-01

    Some of the lingering challenges within the current paradigm of vibration energy harvesting (VEH) involve narrow operational frequency range and the inevitable non-resonant response from broadband noise excitations. Such VEHs are only suitable for limited applications with fixed sinusoidal vibration, and fail to capture a large spectrum of the real world vibration. Various arraying designs, frequency tuning schemes and nonlinear vibratory approaches have only yielded modest enhancements. To fundamentally address this, the paper proposes and explores the potentials in using highly nonlinear magnetic spring force to activate an autoparametric oscillator, in order to realize an inherently broadband resonant system. Analytical and numerical modelling illustrate that high spring nonlinearity derived from magnetic levitation helps to promote the 2:1 internal frequency matching required to activate parametric resonance. At the right internal parameters, the resulting system can intrinsically exhibit semi-resonant response regardless of the bandwidth of the input vibration, including broadband white noise excitation. (paper)

  7. Service Differentiation in Residential Broadband Networks

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias

    2004-01-01

    As broadband gains widespread adoption with residential users, revenue generating voice- and video-services have not yet taken off. This slow uptake is often attributed to lack of Quality of Service management in residential broadband networks. To resolve this and induce service variety, network...... access providers are implementing service differentiation in their networks where voice and video gets prioritised before data. This paper discusses the role of network access providers in multipurpose packet based networks and the available migration strategies for supporting multimedia services...... in digital subscriber line (DSL) based residential broadband networks. Four possible implementation scenarios and their technical characteristics and effects are described. To conclude, the paper discusses how network access providers can be induced to open their networks for third party service providers....

  8. Policy factors affecting broadband development in Poland

    DEFF Research Database (Denmark)

    Henten, Anders; Windekilde, Iwona Maria

    2014-01-01

    of telecommunications network development in Poland than other countries in the European Union is the reason that the circumstances and also the effects of the implementation of some solutions of the EU regulation model are different in Poland than in the most developed EU countries. The aim of the paper is to examine...... and discuss broadband access development in Poland and the policy factors influencing this development as well as to examine national strategies used to stimulate service and infrastructure competition in Poland. There are, indeed, many other factors affecting broadband development such as the income level....../distribution in the country and the infrastructural point of departure. The paper, therefore, analyses the implications of the policy initiatives in light of these basic conditions and the broader context of factors influencing broadband development. In the paper, different kinds of policy initiatives are examined...

  9. Ionic polarization

    International Nuclear Information System (INIS)

    Mahan, G.D.

    1992-01-01

    Ferroelectricity occurs in many different kinds of materials. Many of the technologically important solids, which are ferroelectric, can be classified as ionic. Any microscopic theory of ferroelectricity must contain a description of local polarization forces. We have collaborated in the development of a theory of ionic polarization which is quite successful. Its basic assumption is that the polarization is derived from the properties of the individual ions. We have applied this theory successfully to diverse subjects as linear and nonlinear optical response, phonon dispersion, and piezoelectricity. We have developed numerical methods using the local Density approximation to calculate the multipole polarizabilities of ions when subject to various fields. We have also developed methods of calculating the nonlinear hyperpolarizability, and showed that it can be used to explain light scattering experiments. This paper elaborates on this polarization theory

  10. Polarization experiments

    International Nuclear Information System (INIS)

    Halzen, F.

    1977-02-01

    In a theoretical review of polarization experiments two important points are emphasized: (a) their versatility and their relevance to a large variety of aspects of hadron physics (tests of basic symmetries; a probe of strong interaction dynamics; a tool for hadron spectroscopy); (b) the wealth of experimental data on polarization parameters in pp and np scattering in the Regge language and in the diffraction language. (author)

  11. Broadband terahertz generation of metamaterials

    Science.gov (United States)

    Luo, Liang; Wang, Jigang; Koschny, Thomas; Wegener, Martin; Soukoulis, Costas M.

    2017-06-20

    Provided are systems and methods to generate single-cycle THz pulses from a few tens of nanometers thin layer of split ring resonators (SRRs) via optical rectification of femtosecond laser pulses. The emitted THz radiation, with a spectrum ranging from about 0.1 to 4 THz, arises exclusively from pumping the magnetic-dipole resonance of SRRs around 200 THz. This resonant enhancement, together with pump polarization dependence and power scaling of the THz emission, underpins the nonlinearity from optically induced circulating currents in SRRs, with a huge effective nonlinear susceptibility of 0.8.times.10.sup.-16 m.sup.2/V that far exceeds surface nonlinearities of both thin films and bulk organic/inorganic crystals and sheet nonlinearities of non-centrosymmetric materials such as ZnTe.

  12. 4G Mobile Broadband Networks

    DEFF Research Database (Denmark)

    Kardaras, Georgios

    This thesis has investigated a number of methods for optimizing energy and spectrum performance for 4G commercial radio access applications. The research interest is narrowed down to distributed base station architectures and in particular the remote radio module. Designing energy efficient radio...... and a comparison with conventional base station architectures was realized. This analysis demonstrated that efficient hardware, intelligent software and self-organized subsystems can result in decreasing substantially power wastes. The advantages of optical fiber as transport medium for relaying baseband modulated...... digital predistortion block is proposed based on cartesian to polar conversion. It has been designed and implemented on a low-cost FPGA, overcoming the challenges imposed by the logical size and timing constraints....

  13. Participation in the broadband society in Denmark

    DEFF Research Database (Denmark)

    Falch, Morten; Henten, Anders; Skouby, Knud Erik

    2009-01-01

    passed the threshold set by the EU with respect to the relevance of initiating a discussion on the implementation of a universal service obligation on broadband. As documented in the paper, there are groups among primarily the elderly and the unemployed who do not have Internet access. Their own......The purpose of the paper is to provide an empirical overview of broadband developments in Denmark. The overview includes sections on coverage and penetration, connection speeds, retail prices, competition, interconnection prices, and residential access to Internet. The documentation shows...

  14. Polarization measurement for internal polarized gaseous targets

    International Nuclear Information System (INIS)

    Ye Zhenyu; Ye Yunxiu; Lv Haijiang; Mao Yajun

    2004-01-01

    The authors present an introduction to internal polarized gaseous targets, polarization method, polarization measurement method and procedure. To get the total nuclear polarization of hydrogen atoms (including the polarization of the recombined hydrogen molecules) in the target cell, authors have measured the parameters relating to atomic polarization and polarized hydrogen atoms and molecules. The total polarization of the target during our measurement is P T =0.853 ± 0.036. (authors)

  15. VT Wireline Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  16. VT Public Locations of Broadband Data - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  17. VT Public Locations of Broadband Data - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  18. VT Public Locations of Broadband Data - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  19. VT Cable Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  20. VT Total Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  1. VT Cable Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  2. VT Detailed Broadband Availability by Census Block -12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  3. VT Detailed Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  4. VT Detailed Broadband Availability by Census Block -12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  5. VT Detailed Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  6. VT Wireline Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  7. VT Wireless Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  8. VT Total Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  9. VT Wireline Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  10. VT Wireless Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  11. VT Total Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  12. VT Cable Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  13. VT Wireless Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  14. VT Detailed Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  15. VT Total Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  16. VT DSL Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  17. VT Wireline Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  18. VT DSL Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  19. VT Wireless Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  20. 7 CFR 1738.11 - Availability of broadband service.

    Science.gov (United States)

    2010-01-01

    ..., DEPARTMENT OF AGRICULTURE RURAL BROADBAND ACCESS LOANS AND LOAN GUARANTEES Loan Purposes and Basic Policies... given to loans to finance service to eligible rural communities in which broadband service is not...

  1. VT Wireless Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  2. VT Public Locations of Broadband Data - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  3. VT DSL Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  4. VT Cable Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  5. VT Wireline Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  6. VT Cable Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  7. VT Wireless Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  8. VT DSL Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  9. VT Wireline Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  10. VT Public Locations of Broadband Data - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  11. VT Cable Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  12. VT Total Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  13. VT Detailed Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  14. VT DSL Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  15. VT DSL Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  16. VT Public Locations of Broadband Data - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  17. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-01-01

    multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which

  18. VT Total Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  19. Broadband and high efficiency all-dielectric metasurfaces for wavefront steering with easily obtained phase shift

    Science.gov (United States)

    Yang, Hui; Deng, Yan

    2017-12-01

    All-dielectric metasurfaces for wavefront deflecting and optical vortex generating with broadband and high efficiency are demonstrated. The unit cell of the metasurfaces is optimized to function as a half wave-plate with high polarization conversion efficiency (94%) and transmittance (94.5%) at the telecommunication wavelength. Under such a condition, we can get rid of the complicated parameter sweep process for phase shift selecting. Hence, a phase coverage ranges from 0 to 2 π can be easily obtained by introducing the Pancharatnam-Berry phase. Metasurfaces composed of the two pre-designed super cells are demonstrated for optical beam deflecting and vortex beam generating. It is found that the metasurfaces with more phase shift sampling points (small phase shift increment) exhibit better performance. Moreover, optical vortex beams can be generated by the designed metasurfaces within a wavelength range of 200 nm. These results will provide a viable route for designing broadband and high efficiency devices related to phase modulation.

  20. Sources of polarized neutrons

    International Nuclear Information System (INIS)

    Walter, L.

    1983-01-01

    Various sources of polarized neutrons are reviewed. Monoenergetic source produced with unpolarized or polarized beams, white sources of polarized neutrons, production by transmissions through polarized hydrogen targets and polarized thermal neutronsare discussed, with appropriate applications included. (U.K.)

  1. A high extinction ratio THz polarizer fabricated by double-bilayer wire grid structure

    Science.gov (United States)

    Lu, Bin; Wang, Haitao; Shen, Jun; Yang, Jun; Mao, Hongyan; Xia, Liangping; Zhang, Weiguo; Wang, Guodong; Peng, Xiao-Yu; Wang, Deqiang

    2016-02-01

    We designed a new style of broadband terahertz (THz) polarizer with double-bilayer wire grid structure by fabricating them on both sides of silicon substrate. This THz polarizer shows a high average extinction ratio of 60dB in 0.5 to 2.0 THz frequency range and the maximum of 87 dB at 1.06 THz, which is much higher than that of conventional monolayer wire grid polarizers and single-bilayer wire grid ones.

  2. Broadband luminescent materials in waveguide geometry

    NARCIS (Netherlands)

    Pollnau, Markus

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The

  3. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

    Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...

  4. WIRELESS FIDELITY (Wi-Fi) BROADBAND NETWORK ...

    African Journals Online (AJOL)

    ES Obe

    broadband speed and coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet ... Microwave Access (WiMAX), IEEE 802.11 standards. 1.0 INTRODUCTION .... These 2G systems provided circuit- switched data ...

  5. 77 FR 36903 - Accelerating Broadband Infrastructure Deployment

    Science.gov (United States)

    2012-06-20

    ... the Nation's global competitiveness in the 21st century, driving job creation, promoting innovation, and expanding markets for American businesses. Broadband access also affords public safety agencies... infrastructure has been deployed in a vast majority of communities across the country, today too many areas still...

  6. 75 FR 27984 - Broadband Technology Opportunities Program

    Science.gov (United States)

    2010-05-19

    ... applications, including: streaming video (surveillance, remote monitoring); digital imaging; automatic vehicle location; computer-aided dispatching; electronic mail; mapping and GPS; remote database access; report... entities to deploy public safety broadband systems using the 700 MHz spectrum licensed to the PSST.\\13\\ The...

  7. 75 FR 29516 - Broadband Researchers' Data Workshop

    Science.gov (United States)

    2010-05-26

    ... foundation for long-term economic stability and prosperity.\\1\\ The increased availability and use of... telecommunications policies pertaining to the Nation's economic and technological advancement. In order to achieve... stakeholders to develop and implement economic and regulatory policies that foster broadband deployment and...

  8. Electromagnetically induced transparency with broadband laser pulses

    International Nuclear Information System (INIS)

    Yavuz, D. D.

    2007-01-01

    We suggest a scheme to slow and stop broadband laser pulses inside an atomic medium using electromagnetically induced transparency. Extending the suggestion of Harris et al. [Phys. Rev. Lett. 70, 552 (1993)], the key idea is to use matched Fourier components for the probe and coupling laser beams

  9. Management of broadband technology and innovation policy, deployment, and use

    CERN Document Server

    Choudrie, Jyoti

    2013-01-01

    When one considers broadband, the Internet immediately springs to mind. However, broadband is impacting society in many ways. For instance, broadband networks can be used to deliver healthcare or community related services to individuals who don't have computers, have distance as an issue to contend with, or don't use the internet. Broadband can support better management of scarce energy resources with the advent of smart grids, enables improved teleworking capacity and opens up a world of new entertainment possibilities. Yet scholarly examinations of broadband technology have so far examin

  10. Polarization study

    International Nuclear Information System (INIS)

    Nurushev, S.B.

    1989-01-01

    Brief review is presented of the high energy polarization study including experimental data and the theoretical descriptions. The mostimportant proposals at the biggest accelerators and the crucial technical developments are also listed which may become a main-line of spin physics. 35 refs.; 10 figs.; 4 tabs

  11. Polar Stratigraphy

    Science.gov (United States)

    1999-01-01

    These three images were taken on three different orbits over the north polar cap in April 1999. Each shows a different part of the same ice-free trough. The left and right images are separated by a distance of more than 100 kilometers (62 miles). Note the similar layers in each image.

  12. Local government broadband policies for areas with limited Internet access

    Directory of Open Access Journals (Sweden)

    Yoshio Arai

    2014-03-01

    Full Text Available Despite their wide diffusion in developed countries, broadband services are still limited in areas where providing them is not profitable for private telecom carriers. To address this, many local governments in Japan have implemented broadband deployment projects subsidized by the national government. In this paper, we discuss local government broadband policies based on survey data collected from municipalities throughout the country. With the support of national promotion policies, broadband services were rapidly introduced to most local municipalities in Japan during the 2000s. Local government deployment policies helped to reduce the number of areas with no broadband access. A business model based on the Indefeasible Right of Use (IRU contract between a private telecom carrier and a local government has been developed in recent years. Even local governments without the technical capacity to operate a broadband business can introduce broadband services into their territory using the IRU business model.

  13. Broadband and high-efficient terahertz wave deflection based on C-shaped complex metamaterials with phase discontinuities

    KAUST Repository

    Tian, Zhen

    2013-09-01

    A terahertz metamaterial comprised of C-shaped SRRs was experimentally devised and demonstrated to exhibit high-efficient and broadband anomalous refraction with strong phase discontinuities. The generalized refraction properties of the proposed metamaterial, including the effect of various incident angles and polarizations were investigated at broad terahertz frequencies. By employing such metasurface, we demonstrated a simple method to tailor transmission and phase of terahertz wave. © 2013 IEEE.

  14. Broadband and high-efficient terahertz wave deflection based on C-shaped complex metamaterials with phase discontinuities

    KAUST Repository

    Tian, Zhen; Zhang, Xueqian; Yue, Weisheng; Gu, Jianqiang; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2013-01-01

    A terahertz metamaterial comprised of C-shaped SRRs was experimentally devised and demonstrated to exhibit high-efficient and broadband anomalous refraction with strong phase discontinuities. The generalized refraction properties of the proposed metamaterial, including the effect of various incident angles and polarizations were investigated at broad terahertz frequencies. By employing such metasurface, we demonstrated a simple method to tailor transmission and phase of terahertz wave. © 2013 IEEE.

  15. Polarization Control for Silicon Photonic Circuits

    Science.gov (United States)

    Caspers, Jan Niklas

    In recent years, the field of silicon photonics has received much interest from researchers and companies across the world. The idea is to use photons to transmit information on a computer chip in order to increase computational speed while decreasing the power required for computation. To allow for communication between the chip and other components, such as the computer memory, these silicon photonics circuits need to be interfaced with optical fiber. Unfortunately, in order to interface an optical fiber with an integrated photonics circuit two major challenges need to be overcome: a mode-size mismatch as well as a polarization mismatch. While the problem of mode-size has been well investigated, the polarization mismatch has yet to be addressed. In order to solve the polarization mismatch one needs to gain control over the polarization of the light in a waveguide. In this thesis, I will present the components required to solve the polarization mismatch. Using a novel wave guiding structure, the hybrid plasmonic waveguide, an ultra-compact polarization rotator is designed, fabricated, and tested. The hybrid plasmonic rotator has a performance similar to purely dielectric rotators while being more than an order of magnitude smaller. Additionally, a broadband hybrid plasmonic coupler is designed and measured. This coupler has a performance similar to dielectric couplers while having a footprint an order of magnitude smaller. Finally, a system solution to the polarization mismatch is provided. The system, a polarization adapter, matches the incoming changing polarization from the fiber actively to the correct one of the silicon photonics circuit. The polarization adapter is demonstrated experimentally to prove its operation. This proof is based on dielectric components, but the aforementioned hybrid plasmonic waveguide components would make the system more compact.

  16. Broadband spectral observation of a dMe star radio flare

    International Nuclear Information System (INIS)

    Guedel, M.; Benz, A.O.; Fuerst, E.; Simett, G.M.; Davis, R.J.

    1989-01-01

    A flare on the dMe star AD Leonis was simultaneously observed with the radio telescopes in Effelsberg, Jodrell Bank, and Arecibo using spectrometers at 1665, 166 and 1415 MHz with bandwidths of 25, 100 and 40 MHz respectively. The time coincidence confirms the stellar origin of the radiation. The flare emission was resolved into a multitude of broadband pulsations. The e-folding rise and decay times were of the order of the time resolution of the Effelsberg data (125 ms), or less. The circular polarization was ∼ 100%. Similar bursts, but 4 orders of magnitude less powerful, have been observed from the sun at lower frequencies

  17. Design of broadband multilayer dichroic coating for a high-efficiency solar energy harvesting system.

    Science.gov (United States)

    Jiachen, Wang; Lee, Sang Bae; Lee, Kwanil

    2015-05-20

    We report on the design and performance of a broadband dichroic coating for a solar energy conversion system. As a spectral beam splitter, the coating facilitates a hybrid system that combines a photovoltaic cell with a thermal collector. When positioned at a 45° angle with respect to incident light, the coating provides high reflectance in the 40-1100 nm and high transmission in the 1200-2000 nm ranges for a photovoltaic cell and a thermal collector, respectively. Numerical simulations show that our design leads to a sharp transition between the reflection and transmission bands, low ripples in both bands, and slight polarization dependence.

  18. Experimental study of broadband unidirectional splitting in photonic crystal gratings with broken structural symmetry

    Science.gov (United States)

    Colak, Evrim; Serebryannikov, Andriy E.; Ozgur Cakmak, A.; Ozbay, Ekmel

    2013-04-01

    It is experimentally demonstrated that the combination of diode and splitter functions can be realized in one broadband reciprocal device. The suggested performance is based on the dielectric photonic crystal grating whose structural symmetry is broken owing to non-deep corrugations placed at one of the two interfaces. The study has been performed at a normally incident beam-type illumination obtained from a microwave horn antenna. The two unidirectionally transmitted, deflected beams can show large magnitude and high contrast, while the angular distance between their maxima is 90° and larger. The dual-band unidirectional splitting is possible when using TM and TE polarizations.

  19. Broadband standard dipole antenna for antenna calibration

    Science.gov (United States)

    Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

    1995-06-01

    Antenna calibration of EMI antennas is mostly performed by the standard antenna method at an open-field test site using a specially designed dipole antenna as a reference. In order to develop broadband standard antennas, the antenna factors of shortened dipples are theoretically investigated. First, the effects of the dipole length are analyzed using the induced emf method. Then, baluns and loads are examined to determine their influence on the antenna factors. It is found that transformer-type baluns are very effective for improving the height dependence of the antenna factors. Resistive loads are also useful for flattening the frequency dependence. Based on these studies, a specification is developed for a broadband standard antenna operating in the 30 to 150 MHz frequency range.

  20. Broadband phase-preserved optical elevator

    OpenAIRE

    Luo, Yuan; Han, Tiancheng; Zhang, Baile; Qiu, Cheng-Wei; Barbastathis, George

    2011-01-01

    Phase-preserved optical elevator is an optical device to lift up an entire plane virtually without distortion in light path or phase. Using transformation optics, we have predicted and observed the realization of such a broadband phase-preserved optical elevator, made of a natural homogeneous birefringent crystal without resorting to absorptive and narrowband metamaterials involving time-consuming nano-fabrication. In our demonstration, the optical elevator is designed to lift a sheet upwards...

  1. Switched Broadband Services For The Home

    Science.gov (United States)

    Sawyer, Don M.

    1990-01-01

    In considering the deployment of fiber optics to the residence, two critical questions arise: what are the leading services that could be offered to justify the required investment; and what is the nature of the business that would offer these services to the consumer ? This talk will address these two questions together with the related issue of how the "financial engine" of today's television distribution infrastructure - TV advertising - would be affected by an open access system based on fiber optics coupled with broadband switching. On the business side, the talk concludes that the potential for open ended capacity expansion, fair competition between service providers, and new interactive services inherent in an open access, switched broadband system are the critical items in differentiating it from existing video and TV distribution systems. On the question of broadband services, the talk will highlight several new opportunities together with some findings from recent market research conducted by BNR. The talk will show that there are variations on existing services plus many new services that could be offered and which have real consumer appeal. The postulated open access system discussed here is visualized as having ultimately 1,000 to 2,000 video channels available to the consumer. Although this may appear to hopelessly fragment the TV audience and destroy the current TV advertising infrastructure, the technology of open access, switched broadband will present many new advertising techniques, which have the potential to be far more effective than those available today. Some of these techniques will be described in this talk.

  2. Broadband Spectroscopy of Nanoporous-Gold Promoter

    Directory of Open Access Journals (Sweden)

    S. K. Nakatani

    2014-02-01

    Full Text Available The efficiency of UV photocatalysis on TiO2 particles was increased by mixing TiO2 particles with nanoporous gold (NPG with pore diameters of 10–40 nm. This means that NPG acts as a promoter in the photocatalytic reaction of TiO2. Broadband spectroscopic results from millimeter wave to ultra violet of NPG membrane are discussed to estimate plasmonic effect on the catalysis.

  3. Broadband S-band class E HPA

    NARCIS (Netherlands)

    Wanum, M.; van Dijk, R.; de Hek, A.P.; van Vliet, Frank Edward

    2009-01-01

    A broadband class E High Power Amplifier (HPA) is presented. This HPA is designed to operate at S-band (2.75 to 3.75 GHz). A power added efficiency of 50% is obtained for the two stage amplifier with an output power of 35.5 dBm on a chip area of 5.25 times 2.8 mm2.

  4. Diagonalizing sensing matrix of broadband RSE

    International Nuclear Information System (INIS)

    Sato, Shuichi; Kokeyama, Keiko; Kawazoe, Fumiko; Somiya, Kentaro; Kawamura, Seiji

    2006-01-01

    For a broadband-operated RSE interferometer, a simple and smart length sensing and control scheme was newly proposed. The sensing matrix could be diagonal, owing to a simple allocation of two RF modulations and to a macroscopic displacement of cavity mirrors, which cause a detuning of the RF modulation sidebands. In this article, the idea of the sensing scheme and an optimization of the relevant parameters will be described

  5. Broadband luminescence in liquid-solid transition

    CERN Document Server

    Achilov, M F; Trunilina, O V

    2002-01-01

    Broadband luminescence (BBL) intensity behavior in liquid-solid transition in polyethyleneglycol-600 has been established. Oscillation of BBL intensity observed in liquid-polycrystal transition are not found to observed in liquid-amorphous solid transition. It is shown that application of the theory of electron state tails to interpretation of BBL spectral properties in liquids demands restriction. BBL spectroscopy may be applied for optimization of preparation of polymers with determined properties. (author)

  6. Broadband electromagnetic analysis of compacted kaolin

    International Nuclear Information System (INIS)

    Bore, Thierry; Scheuermann, Alexander; Wagner, Norman; Cai, Caifang

    2017-01-01

    The mechanical compaction of soil influences not only the mechanical strength and compressibility but also the hydraulic behavior in terms of hydraulic conductivity and soil suction. At the same time, electric and dielectric parameters are increasingly used to characterize soil and to relate them with mechanic and hydraulic parameters. In the presented study electromagnetic soil properties and suction were measured under defined conditions of standardized compaction tests. The impact of external mechanical stress conditions of nearly pure kaolinite was analyzed on soil suction and broadband electromagnetic soil properties. An experimental procedure was developed and validated to simultaneously determine mechanical, hydraulic and broadband (1 MHz–3 GHz) electromagnetic properties of the porous material. The frequency dependent electromagnetic properties were modeled with a classical mixture equation (advanced Lichtenecker and Rother model, ALRM) and a hydraulic-mechanical-electromagnetic coupling approach was introduced considering water saturation, soil structure (bulk density, porosity), soil suction (pore size distribution, water sorption) as well as electrical conductivity of the aqueous pore solution. Moreover, the relaxation behavior was analyzed with a generalized fractional relaxation model concerning a high-frequency water process and two interface processes extended with an apparent direct current conductivity contribution. The different modeling approaches provide a satisfactory agreement with experimental data for the real part. These results show the potential of broadband electromagnetic approaches for quantitative estimation of the hydraulic state of the soil during densification. (paper)

  7. Design and fabrication of broadband rugate filter

    International Nuclear Information System (INIS)

    Zhang Jun-Chao; Fang Ming; Shao Yu-Chuan; Jin Yun-Xia; He Hong-Bo

    2012-01-01

    The design and the deposition of a rugate filter for broadband applications are discussed. The bandwidth is extended by increasing the rugate period continuously with depth. The width and the smoothness of the reflection band with the distribution of the periods are investigated. The improvement of the steepness of the stopband edges and the suppression of the side lobes in the transmission zone are realized by adding two apodized rugate structures with fixed periods at the external broadband rugate filter interfaces. The rapidly alternating deposition technology is used to fabricate a rugate filter sample. The measured transmission spectrum with a reflection bandwidth of approximately 505 nm is close to that of the designed broadband rugate filter except a transmittance peak in the stopband. Based on the analysis of the cross-sectional scanning electron microscopic image of the sample, it is found that the transmission peak is most likely to be caused by the instability of the deposition rate. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  8. Broadband dielectric spectroscopy of phonons and polar nanoclusters in PbMg.sub.1/3./sub.Nb.sub.2/3./sub.O.sub.3./sub.-35%PbTiO.sub.3./sub. ceramics: Grain size effects

    Czech Academy of Sciences Publication Activity Database

    Bovtun, Viktor; Kamba, Stanislav; Veljko, Sergiy; Nuzhnyy, Dmitry; Kroupa, Jan; Savinov, Maxim; Vaněk, Přemysl; Petzelt, Jan; Holc, J.; Kosec, M.; Amorin, H.; Alguero, M.

    2009-01-01

    Roč. 79, č. 10 (2009), 104111/1-104111/12 ISSN 1098-0121 R&D Projects: GA MŠk OC 101; GA ČR(CZ) GA202/09/0682; GA ČR(CZ) GA202/06/0403; GA MŠk OC09023 Institutional research plan: CEZ:AV0Z10100520 Keywords : polar clusters * relaxor ferroelectrics * soft modes * phonons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009 http://link.aps.org/doi/10.1103/PhysRevB.79.104111

  9. Broadband perfect infrared absorption by tuning epsilon-near-zero and epsilon-near-pole resonances of multilayer ITO nanowires.

    Science.gov (United States)

    Zhou, Kun; Cheng, Qiang; Song, Jinlin; Lu, Lu; Jia, Zhihao; Li, Junwei

    2018-01-01

    We numerically investigate the broadband perfect infrared absorption by tuning epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) resonances of multilayer indium tin oxide nanowires (ITO NWs). The monolayer ITO NWs array shows intensive absorption at ENZ and ENP wavelengths for p polarization, while only at the ENP wavelength for s polarization. Moreover, the ENP resonances are almost omnidirectional and the ENZ resonances are angularly dependent. Therefore, the absorption bandwidth is broader for p polarization than that for s polarization when polarized waves are incident obliquely. The ENZ resonances can be tuned by altering the doping concentration and volume filling factor of ITO NWs. However, the ENP resonances only can be tuned by changing the doping concentration of ITO NWs, and volume filling factor impacts little on the ENP resonances. Based on the strong absorption properties of each layer at their own ENP and ENZ resonances, the tuned absorption of the bilayer ITO NWs with the different doping concentrations can be broader and stronger. Furthermore, multilayer ITO NWs can achieve broadband perfect absorption by controlling the doping concentration, volume filling factor, and length of the NWs in each layer. This study has the potential to apply to applications requiring efficient absorption and energy conversion.

  10. Broadband Radio Polarimetry of Fornax A. I. Depolarized Patches Generated by Advected Thermal Material from NGC 1316

    Science.gov (United States)

    Anderson, C. S.; Gaensler, B. M.; Heald, G. H.; O’Sullivan, S. P.; Kaczmarek, J. F.; Feain, I. J.

    2018-03-01

    We present observations and analysis of the polarized radio emission from the nearby radio galaxy Fornax A over 1.28–3.1 GHz, using data from the Australia Telescope Compact Array. In this, the first of two associated papers, we use modern broadband polarimetric techniques to examine the nature and origin of conspicuous low-polarization (low-p) patches in the lobes. We resolve the (low-p) patches and find that their low fractional polarization is associated with complicated frequency-dependent interference in the polarized signal generated by Faraday effects along the line of sight (LOS). The low-p patches are spatially correlated with interfaces in the magnetic structure of the lobe, across which the LOS-projected magnetic field changes direction. Spatial correlations with the sky-projected magnetic field orientation and structure in total intensity are also identified and discussed. We argue that the (low-p) patches, along with associated reversals in the LOS magnetic field and other related phenomena, are best explained by the presence of { \\mathcal O }({10}9) {M}ȯ of magnetized thermal plasma in the lobes, structured in shells or filaments, and likely advected from the interstellar medium of NCG 1316 or its surrounding intracluster medium. Our study underscores the power and utility of spatially resolved, broadband, full-polarization radio observations to reveal new facets of flow behaviors and magneto-ionic structure in radio lobes and their interplay with the surrounding environment.

  11. Broadband and short (10-ps) pulse generation on Nova

    International Nuclear Information System (INIS)

    Perry, M.D.; Browning, D.; Bibeau, C.; Patterson, F.G.; Wilcox, R.; Henesian, M.

    1990-01-01

    The ability to produce high power broadband pulses for purposes of focal spot beam smoothing has recently become an important issue in inertial confinement fusion (ICF). As the first step toward the generation and propagation of such pulses on Nova, the authors have performed a series of experiments with 10-ps pulses. Aside from the inherently broad bandwidth, these short pulses have important applications in ICF experiments and x-ray laser research. The author's experimental results are discussed. The short pulses were produced by diffraction grating pulse compression of chirped pulses formed from self-phase modulation in a single-mode 10-m fused silica fiber. Use of such a short fiber produces a nonlinearly chirped spectrum of 0.74 nm. The central nearly linearly chirped 0.26 nm is selected by polarization discrimination and compressed using 1800-line/mm diffraction gratings to a nearly Gaussian pulse of 10 ps FWHM with an energy contrast ratio of 20:1. This 1-nJ pulse is injected into a Nova amplifier chain with selected amplifiers unfired

  12. Polar Polygons

    Science.gov (United States)

    2005-01-01

    18 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-outlined polygons on a frost-covered surface in the south polar region of Mars. In summer, this surface would not be bright and the polygons would not have dark outlines--these are a product of the presence of seasonal frost. Location near: 77.2oS, 204.8oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  13. Broadband pulsed difference frequency generation laser source centered 3326 nm based on ring fiber lasers

    Science.gov (United States)

    Chen, Guangwei; Li, Wenlei

    2018-03-01

    A broadband pulsed mid-infrared difference frequency generation (DFG) laser source based on MgO-doped congruent LiNbO3 bulk is experimentally demonstrated, which employs a homemade pulsed ytterbium-doped ring fiber laser and a continuous wave erbium-doped ring fiber laser to act as seed sources. The experimental results indicate that the perfect phase match crystal temperature is about 74.5∘C. The maximum spectrum bandwidth of idler is about 60 nm with suitable polarization states of fundamental lights. The central wavelength of idlers varies from 3293 nm to 3333 nm over the crystal temperature ranges of 70.4-76∘C. A jump of central wavelength exists around crystal temperature of 72∘C with variation of about 30 nm. The conversion efficiency of DFG can be tuned with the crystal temperature and polarization states of fundamental lights.

  14. Strategic Polarization.

    Science.gov (United States)

    Kalai, Adam; Kalai, Ehud

    2001-08-01

    In joint decision making, similarly minded people may take opposite positions. Consider the example of a marriage in which one spouse gives generously to charity while the other donates nothing. Such "polarization" may misrepresent what is, in actuality, a small discrepancy in preferences. It may be that the donating spouse would like to see 10% of their combined income go to charity each year, while the apparently frugal spouse would like to see 8% donated. A simple game-theoretic analysis suggests that the spouses will end up donating 10% and 0%, respectively. By generalizing this argument to a larger class of games, we provide strategic justification for polarization in many situations such as debates, shared living accommodations, and disciplining children. In some of these examples, an arbitrarily small disagreement in preferences leads to an arbitrarily large loss in utility for all participants. Such small disagreements may also destabilize what, from game-theoretic point of view, is a very stable equilibrium. Copyright 2001 Academic Press.

  15. Rail-based Broadband Synthetic Aperture Ocean Measurement System

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Enables collection of broadband acoustic scattering databases where acoustic sources and receivers can be translated on a precise linear path under program...

  16. Handheld, Broadband Electromagnetic UXO Sensor: Cost & Performance Report

    National Research Council Canada - National Science Library

    Won, I. J; SanFilipo, Bill; Oren, Alex

    2006-01-01

    The broadband electromagnetic sensor improvement and demonstration undertaken in this project took the prototype GEM-3 and evolved it into an operational sensor with increased bandwidth and dynamic...

  17. Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors

    Directory of Open Access Journals (Sweden)

    Masaki Kanao

    2014-06-01

    Full Text Available “Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147, the GAmburtsev Mountain SEISmic experiment (GAMSEIS, a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185 were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A, Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN in southern high latitude.

  18. Resource Management in Broadband Communication Networks

    DEFF Research Database (Denmark)

    Hansen, Mads Stenhuus

    2003-01-01

    . The first part gives a brief description of some of the existing protocols for routing and controlling resources, such as RSVP, OSPF, BGP, PNNI, etc. The remaining part concerns the following two fundamentally different approaches to resource management etc.: - Software agents - Simulated ants......This thesis - Resource Management in Broadband Communication Networks - deals with different ways of optimizing the available resources of data- or telecommunication networks. Especially topics like optimal routing, load balancing and fast recovery of routes in case of link failures are covered...

  19. Designing Broadband Access Networks with Triple Redundancy

    DEFF Research Database (Denmark)

    Pedersen, Jens Myrup; Riaz, Muhammad Tahir; Knudsen, Thomas Phillip

    2005-01-01

    An architecture is proposed for designing broadband access networks, which offer triple redundancy to the end users, resulting in networks providing connectivity even in case of any two independent node or line failures. Two physically independent connections are offered by fiber, and the last...... provided by some wireless solution. Based on experience with planning Fiber To The Home, the architecture is designed to meet a number of demands, making it practicable and useful in realworld network planning. The proposed wired topology is planar, and suitable for being fitted onto the road network...

  20. Broadband Planar 5:1 Impedence Transformer

    Science.gov (United States)

    Ehsan, Negar; Hsieh, Wen-Ting; Moseley, Samuel H.; Wollack, Edward J.

    2015-01-01

    This paper presents a broadband Guanella-type planar impedance transformer that transforms so 50 omega to 10 omega with a 10 dB bandwidth of 1-14GHz. The transformer is designed on a flexible 50 micrometer thick polyimide substrate in microstrip and parallel-plate transmission line topologies, and is Inspired by the traditional 4:1 Guanella transformer. Back-to-back transformers were designed and fabricated for characterization in a 50 omega system. Simulated and measured results are in excellent agreement.

  1. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison...... to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View...

  2. Optimizing UV Index determination from broadband irradiances

    Science.gov (United States)

    Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

    2018-03-01

    A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

  3. Source of broadband Jovian Kilometric radiation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.; Leblanc, Y.

    1987-02-01

    Broadband Jovian Kilometric radiation was observed by Voyagers 1 and 2 to be beamed away from the zenomagnetic equatorial plane. Two theories were proposed for the equatorial shadow zone. One suggested that Io plasma torus forms an obstacle to radiation produced on auroral field lines. The other theory proposed that the source is located on the outer flanks of the torus, the beaming being inherent to the emission mechanism. Results are presented which indicate that the latter is consistent with the observations and it would appear that the emission is produced by linear mode conversion of electrostatic upper hybrid to electromagnetic waves in plasma density gradients.

  4. Source of broadband Jovian Kilometric radiation

    International Nuclear Information System (INIS)

    Jones, D.; Leblanc, Y.

    1987-01-01

    Broadband Jovian Kilometric radiation was observed by Voyagers 1 and 2 to be beamed away from the zenomagnetic equatorial plane. Two theories were proposed for the equatorial shadow zone. One suggested that Io plasma torus forms an obstacle to radiation produced on auroral field lines. The other theory proposed that the source is located on the outer flanks of the torus, the beaming being inherent to the emission mechanism. Results are presented which indicate that the latter is consistent with the observations and it would appear that the emission is produced by linear mode conversion of electrostatic upper hybrid to electromagnetic waves in plasma density gradients

  5. Hyperbolic metamaterials: Nonlocal response regularizes broadband supersingularity

    DEFF Research Database (Denmark)

    Yan, Wei; Wubs, Martijn; Mortensen, N. Asger

    2012-01-01

    We study metamaterials known as hyperbolic media that in the usual local-response approximation exhibit hyperbolic dispersion and an associated broadband singularity in the density of states. Instead, from the more microscopic hydrodynamic Drude theory we derive qualitatively different optical...... properties of these metamaterials, due to the free-electron nonlocal optical response of their metal constituents. We demonstrate that nonlocal response gives rise to a large-wavevector cutoff in the dispersion that is inversely proportional to the Fermi velocity of the electron gas, but also for small...

  6. Peramalan Pengguna Broadband di Indonesia [Forecasting of Broadband Users in Indonesia

    Directory of Open Access Journals (Sweden)

    Azwar Aziz

    2016-07-01

    Full Text Available Negara Indonesia memiliki peluang yang sangat besar untuk merealisasikan potensi pitalebar, mengingat Indonesia memiliki jumlah penduduk 253 juta orang dan pengguna internet 88,1 juta orang pada tahun 2014. Di sisi lain sektor komunikasi (salah satunya termasuk telekomunikasi merupakan satu-satunya sektor yang secara konsisten memberikan kontribusi pertumbuhan terhadap Pendapatan Domestik Bruto (PDB sebesar dua angka (double digit. Kemudian peran penting pemerintah adalah selalu mengantisipasi dalam membuat regulasi telekomunikasi, salah satu nya untuk mempercepat penggelaran prasarana pitalebar, seperti menerbitkan Peraturan Presiden RI. Nomor 96 Tahun 2014 tentang Rencana Pitalebar Indonesia 2014 – 2019.  Secara riil pembangunan jaringan pitalebar di Indonesia masih dilakukan di kota-kota besar, mengingat pengguna telekomunikasi sebagian besar berada di kota-kota besar. Selain itu perangkat hanset atau handphone, ketersediaan di pasaran masih terbatas dan harganya masih mahal. Kajian ini menggunakan metodologi penelitian kuantitatif dengan menghitung peramalan dan kualitatif, dengan melakukan observasi atau pengamatan langsung ke lapangan kepada perusahaan Telkom, Telkomsel, XL Axiata dan Indosat. Selanjutnya hasil penelitian ini diperoleh lima faktor yang mempengaruhi penggunaan pitalebar yaitu jumlah penduduk, produk domestik bruto, pendapatan per kapita, laju pertumbuhan ekonomi dan inflasi, dan laju penetrasi. Selain itu, hasil pitalebar menunjukkan pengguna pitalebar lima tahun kedepan selalu meningkat.*****Indonesia has a tremendous opportunity to implement the potential of broadband, as Indonesia has a population of 253 million people and 88.1 million Internet users in 2014. On the other hand, the communication sector (one of them including telecommunications is the only sector that is consistently contributed to the growth of Gross Domestic Product (GDP as many as two numbers (double-digit. Then the important role of government is

  7. Polarized secondary radioactive beams

    International Nuclear Information System (INIS)

    Zaika, N.I.

    1992-01-01

    Three methods of polarized radioactive nuclei beam production: a) a method nuclear interaction of the non-polarized or polarized charged projectiles with target nuclei; b) a method of polarization of stopped reaction radioactive products in a special polarized ion source with than following acceleration; c) a polarization of radioactive nuclei circulating in a storage ring are considered. Possible life times of the radioactive ions for these methods are determined. General schemes of the polarization method realizations and depolarization problems are discussed

  8. Polar crane

    International Nuclear Information System (INIS)

    Makosinski, S.

    1981-01-01

    In many applications polar cranes have to be repeatedly positioned with high accuracy. A guidance system is disclosed which has two pairs of guides. Each guide consists of two rollers carried by a sheave rotatable mounted on the crane bridge, the rollers being locatable one on each side of a guideway, e.g. the circular track on which the bridge runs. The pairs of guides are interconnected by respective rope loops which pass around and are locked to the respective pairs of sheaves in such a manner that movement of one guide results in equal movement of the other guide in a sense to maintain the repeatability of positioning of the centre of the bridge. A hydraulically-linked guide system is also described. (author)

  9. Invited Article: An active terahertz polarization converter employing vanadium dioxide and a metal wire grating in total internal reflection geometry

    Science.gov (United States)

    Liu, Xudong; Chen, Xuequan; Parrott, Edward P. J.; Han, Chunrui; Humbert, Georges; Crunteanu, Aurelian; Pickwell-MacPherson, Emma

    2018-05-01

    Active broadband terahertz (THz) polarization manipulation devices are challenging to realize, but also of great demand in broadband terahertz systems. Vanadium dioxide (VO2) shows a promising phase transition for active control of THz waves and provides broadband polarization characteristics when integrated within grating-type structures. We creatively combine a VO2-based grating structure with a total internal reflection (TIR) geometry providing a novel interaction mechanism between the electromagnetic waves and the device, to realize a powerful active broadband THz polarization-controlling device. The device is based on a Si-substrate coated with a VO2 layer and a metal grating structure on top, attached to a prism for generating the TIR condition on the Si-VO2-grating interface. The grating is connected to electrodes for electrically switching the VO2 between its insulating and conducting phases. By properly selecting the incident angle of the THz waves, the grating direction, and the incident polarization state, we first achieved a broadband intensity modulator under a fused silica prism with an average modulation depth of 99.75% in the 0.2-1.1 THz region. Additionally, we realized an active ultra-broadband quarter-wave converter under a Si prism that can be switched between a 45° linear rotator and a quarter wave converter in the 0.8-1.5 THz region. This is the first demonstration of an active quarter-wave converter with ultra-broad bandwidth performance. Our work shows a highly flexible and multifunctional polarization-controlling device for broadband THz applications.

  10. A high throughput liquid crystal light shutter for unpolarized light using polymer polarization gratings

    Science.gov (United States)

    Komanduri, Ravi K.; Lawler, Kris F.; Escuti, Michael J.

    2011-05-01

    We report on a broadband, diffractive, light shutter with the ability to modulate unpolarized light. This polarizer-free approach employs a conventional liquid crystal (LC) switch, combined with broadband Polarization Gratings (PGs) formed with polymer LC materials. The thin-film PGs act as diffractive polarizing beam-splitters, while the LC switch operates on both orthogonal polarization states simultaneously. As an initial experimental proof-of- concept for unpolarized light with +/-7° aperture, we utilize a commercial twisted-nematic LC switch and our own polymer PGs to achieve a peak transmittance of 80% and peak contrast ratio of 230:1. We characterize the optoelectronic performance, discuss the limitations, and evaluate its use in potential nonmechanical shutter applications (imaging and non-imaging).

  11. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    Science.gov (United States)

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

    A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

  12. Asymmetric quantum well broadband thyristor laser

    Science.gov (United States)

    Liu, Zhen; Wang, Jiaqi; Yu, Hongyan; Zhou, Xuliang; Chen, Weixi; Li, Zhaosong; Wang, Wei; Ding, Ying; Pan, Jiaoqing

    2017-11-01

    A broadband thyristor laser based on InGaAs/GaAs asymmetric quantum well (AQW) is fabricated by metal organic chemical vapor deposition (MOCVD). The 3-μm-wide Fabry-Perot (FP) ridge-waveguide laser shows an S-shape I-V characteristic and exhibits a flat-topped broadband optical spectrum coverage of ~27 nm (Δ-10 dB) at a center wavelength of ~1090 nm with a total output power of 137 mW under pulsed operation. The AQW structure was carefully designed to establish multiple energy states within, in order to broaden the gain spectrum. An obvious blue shift emission, which is not generally acquired in QW laser diodes, is observed in the broadening process of the optical spectrum as the injection current increases. This blue shift spectrum broadening is considered to result from the prominent band-filling effect enhanced by the multiple energy states of the AQW structure, as well as the optical feedback effect contributed by the thyristor laser structure. Project supported by the National Natural Science Foundation of China (Nos. 61604144, 61504137). Zhen Liu and Jiaqi Wang contributed equally to this work.

  13. Broadband impedance of the NESTOR storage ring

    International Nuclear Information System (INIS)

    Androsov, V.P.; Gladkikh, P.I.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.

    2011-01-01

    The contributions from lossy and inductive vacuum chamber components to the broadband impedance of the NESTOR storage ring are obtained by using both low-frequency analytical approaches and computer simulations. As was expected considering the small ring circumference (15.44m), the main contributions both to the longitudinal impedance Z || /n and the loss factor k loss come from the RF-cavity. Cavity impedance was also estimated with CST Microwave Studio (CST Studio Suite TM 2006) by simulating coaxial wire method commonly used for impedance measurements. Both estimates agree well. Finally, we performed the simulations of a number of inductive elements with CST Particle Studio 2010 by using wake field solver. We have also evaluated the bunch length in NESTOR taking the conservative estimate of 3 Ohm for the ring broadband impedance and have found that the bunch length s z = 0.5 cm could be obtained in steady state operation mode for the designed bunch current of 10 mA and RF-voltage of 250 kV.

  14. A Design of Double Broadband MIMO Antenna

    Directory of Open Access Journals (Sweden)

    Yanfeng Geng

    2015-01-01

    Full Text Available The MIMO antenna applied to LTE mobile system should be miniaturization and can work in the current communication frequency band; isolation between each antenna unit also should be good so as to reduce loss of radio wave energy and improve the antenna performance of the MIMO system. This paper puts forward the design scheme of a broadband MIMO double antenna. And the design of antenna unit and debugging and related technical measures, such as bending antenna bracket, are both presented; the integration design of high isolation of ultra broadband MIMO antenna is realized on the plate with the volume of 100 × 52 × 0.8 mm3; antenna working bands are 698 MHz~960 MHz and 1710 MHz~2700 MHz; in the whole spectrum, the 10 dB of port isolation can be basically achieved; in low frequency band, the isolation degree of antenna port can reach 12 dB.

  15. Broadband acoustic properties of a murine skull.

    Science.gov (United States)

    Estrada, Héctor; Rebling, Johannes; Turner, Jake; Razansky, Daniel

    2016-03-07

    It has been well recognized that the presence of a skull imposes harsh restrictions on the use of ultrasound and optoacoustic techniques in the study, treatment and modulation of the brain function. We propose a rigorous modeling and experimental methodology for estimating the insertion loss and the elastic constants of the skull over a wide range of frequencies and incidence angles. A point-source-like excitation of ultrawideband acoustic radiation was induced via the absorption of nanosecond duration laser pulses by a 20 μm diameter microsphere. The acoustic waves transmitted through the skull are recorded by a broadband, spherically focused ultrasound transducer. A coregistered pulse-echo ultrasound scan is subsequently performed to provide accurate skull geometry to be fed into an acoustic transmission model represented in an angular spectrum domain. The modeling predictions were validated by measurements taken from a glass cover-slip and ex vivo adult mouse skulls. The flexible semi-analytical formulation of the model allows for seamless extension to other transducer geometries and diverse experimental scenarios involving broadband acoustic transmission through locally flat solid structures. It is anticipated that accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in a broad variety of applications employing transcranial detection or transmission of high frequency ultrasound.

  16. Monochromatic Measurements of the JPSS-1 VIIRS Polarization Sensitivity

    Science.gov (United States)

    McIntire, Jeff; Moyer, David; Brown, Steven W.; Lykke, Keith R.; Waluschka, Eugene; Oudrari, Hassan; Xiong, Xiaoxiong

    2016-01-01

    Polarization sensitivity is a critical property that must be characterized for spaceborne remote sensing instruments designed to measure reflected solar radiation. Broadband testing of the first Joint Polar-orbiting Satellite System (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS) showed unexpectedly large polarization sensitivities for the bluest bands on VIIRS (centered between 400 and 600 nm). Subsequent ray trace modeling indicated that large diattenuation on the edges of the bandpass for these spectral bands was the driver behind these large sensitivities. Additional testing using the National Institute of Standards and Technologies Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources was added to the test program to verify and enhance the model. The testing was limited in scope to two spectral bands at two scan angles; nonetheless, this additional testing provided valuable insight into the polarization sensitivity. Analysis has shown that the derived diattenuation agreed with the broadband measurements to within an absolute difference of about0.4 and that the ray trace model reproduced the general features of the measured data. Additionally, by deriving the spectral responsivity, the linear diattenuation is shown to be explicitly dependent on the changes in bandwidth with polarization state.

  17. Optical broadband in-home networks for converged service delivery

    NARCIS (Netherlands)

    Shi, Y.

    2013-01-01

    Broadband access networks, and in particular fibre-to-the-home (FTTH) networks, are offering abundantly available bandwidth in the local loop with high quality of services. Under such broadband connectivity conditions, in-home networks should not represent the bottleneck for high capacity service

  18. Radio-over-fibre technology for broadband wireless communication systems

    NARCIS (Netherlands)

    Ng'Oma, A.

    2005-01-01

    Wireless coverage of the end-user domain, be it outdoors or indoors (in-building), is poised to become an essential part of broadband communication networks. In order to offer integrated broadband services (combining voice, data, video, multimedia services, and new value added services), these

  19. Broadband Liner Optimization for the Source Diagnostic Test Fan

    Science.gov (United States)

    Nark, Douglas M.; Jones, Michael G.

    2012-01-01

    The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more appealing. This paper describes a broadband acoustic liner optimization study for the scale model Source Diagnostic Test fan. Specifically, in-duct attenuation predictions with a statistical fan source model are used to obtain optimum impedance spectra over a number of flow conditions for three liner locations in the bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Typical tonal liner designs targeting single frequencies at one operating condition are first produced to provide baseline performance information. These are followed by multiple broadband design approaches culminating in a broadband liner targeting the full range of frequencies and operating conditions. The broadband liner is found to satisfy the optimum impedance objectives much better than the tonal liner designs. In addition, the broadband liner is found to provide better attenuation than the tonal designs over the full range of frequencies and operating conditions considered. Thus, the current study successfully establishes a process for the initial design and evaluation of novel broadband liner concepts for complex engine configurations.

  20. Techno-economic evaluation of broadband access technologies

    DEFF Research Database (Denmark)

    Sigurdsson, Halldór Matthias; Skouby, Knud Erik

    2005-01-01

    Broadband for all is an essential element in the EU policy concerning the future of ICT-based society. The overall purpose of this paper is to present a model for evaluation of different broadband access technologies and to present some preliminary results based on the model that has been carried...

  1. Silicon graphene waveguide tunable broadband microwave photonics phase shifter.

    Science.gov (United States)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-04-07

    We propose the use of silicon graphene waveguides to implement a tunable broadband microwave photonics phase shifter based on integrated ring cavities. Numerical computation results show the feasibility for broadband operation over 40 GHz bandwidth and full 360° radiofrequency phase-shift with a modest voltage excursion of 0.12 volt.

  2. The role of public initiatives facilitating investments in broadband infrastructures

    DEFF Research Database (Denmark)

    Falch, Morten; Tadayoni, Reza; Henten, Anders

    2015-01-01

    This paper discusses the role of a developmental approach to broadband policy. The policy approaches made in Denmark and Sweden are compared, and the scope for public intervention at the broadband market is discussed. The paper includes a case study on public intervention in the rural areas of th...

  3. Analisis Perkembangan Internet Broadband di Daerah Perbatasan Sulawesi Utara

    Directory of Open Access Journals (Sweden)

    Riva'atul Adaniah Wahab

    2016-12-01

    Full Text Available Adopsi teknologi internet broadband dapat memberikan dampak ekonomi bagi masyarakat perbatasan. Karenanya pemerataan pembangunan internet broadband di wilayah  ini harus segera diwujudkan. Penelitian deskriptif kuantitatif ini dilaksanakan di wilayah perbatasan Provinsi Sulawesi Utara untuk mengetahui kondisi aspek supply dan demand perkembangan internet broadband di wilayah tersebut. Berdasarkan hasil penelitian, dapat disimpulkan bahwa dari aspek supply, kondisi infrastruktur masih sangat kurang, ketersediaan layanan internet broadband berkualitas tinggi dengan tarif rendah juga masih sulit diwujudkan. Dari aspek demand, stigma atau persepsi masyarakat bahwa internet tidak penting menjadi salah satu faktor penyebab tidak memiliki akses internet. Adapun hambatan yang paling dominan adalah ketidakpahaman dalam penggunaan internet. Faktor ini juga menjadi mendasari literasi internet broadband masyarakat pada level 0 yaitu  tidak peduli akan pentinya internet. Menanggapai kondisi ini, penyusunan dan penetapan kebijakan serta regulasi seperti QoS layanan, tarif interkoneksi, infrastructure sharing dibuat untuk menyediakan internet broadband berkualitas tinggi dengan harga murah. Selain itu distribusi perangkat mobile berharga murah (smartphone juga perlu didorong dengan penerapan TKDN untuk produksi perangkat. Tidak kalah pentingnya adalah peningkatan literasi internet broadband masyarakat melalui sosialisasi atau pelatihan baik formal maupun nonformal. Abstract   Adoption of internet broadband internet can provide the economic impact for border communities. Hence equitable development of internet broadband in the region should be immediately implemented. This quantitative descriptive study was conducted in the border region of North Sulawesi to determine the condition of supply and demand aspects of the development of internet broadband. Based on the results, it can be concluded that from the aspect of supply, the condition of the

  4. Measuring the influence of aerosols and albedo on sky polarization.

    Science.gov (United States)

    Kreuter, A; Emde, C; Blumthaler, M

    2010-11-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

  5. Chaos-assisted broadband momentum transformation in optical microresonators.

    Science.gov (United States)

    Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

    2017-10-20

    The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  6. Chaos-assisted broadband momentum transformation in optical microresonators

    Science.gov (United States)

    Jiang, Xuefeng; Shao, Linbo; Zhang, Shu-Xin; Yi, Xu; Wiersig, Jan; Wang, Li; Gong, Qihuang; Lončar, Marko; Yang, Lan; Xiao, Yun-Feng

    2017-10-01

    The law of momentum conservation rules out many desired processes in optical microresonators. We report broadband momentum transformations of light in asymmetric whispering gallery microresonators. Assisted by chaotic motions, broadband light can travel between optical modes with different angular momenta within a few picoseconds. Efficient coupling from visible to near-infrared bands is demonstrated between a nanowaveguide and whispering gallery modes with quality factors exceeding 10 million. The broadband momentum transformation enhances the device conversion efficiency of the third-harmonic generation by greater than three orders of magnitude over the conventional evanescent-wave coupling. The observed broadband and fast momentum transformation could promote applications such as multicolor lasers, broadband memories, and multiwavelength optical networks.

  7. Analysis of JPSS J1 VIIRS Polarization Sensitivity Using the NIST T-SIRCUS

    Science.gov (United States)

    McIntire, Jeffrey W.; Young, James B.; Moyer, David; Waluschka, Eugene; Oudrari, Hassan; Xiong, Xiaoxiong

    2015-01-01

    The polarization sensitivity of the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) measured pre-launch using a broadband source was observed to be larger than expected for many reflective bands. Ray trace modeling predicted that the observed polarization sensitivity was the result of larger diattenuation at the edges of the focal plane filter spectral bandpass. Additional ground measurements were performed using a monochromatic source (the NIST T-SIRCUS) to input linearly polarized light at a number of wavelengths across the bandpass of two VIIRS spectral bands and two scan angles. This work describes the data processing, analysis, and results derived from the T-SIRCUS measurements, comparing them with broadband measurements. Results have shown that the observed degree of linear polarization, when weighted by the sensor's spectral response function, is generally larger on the edges and smaller in the center of the spectral bandpass, as predicted. However, phase angle changes in the center of the bandpass differ between model and measurement. Integration of the monochromatic polarization sensitivity over wavelength produced results consistent with the broadband source measurements, for all cases considered.

  8. Broadband radio spectro-polarimetric observations of high-Faraday-rotation-measure AGN

    Science.gov (United States)

    Pasetto, Alice; Carrasco-González, Carlos; O'Sullivan, Shane; Basu, Aritra; Bruni, Gabriele; Kraus, Alex; Curiel, Salvador; Mack, Karl-Heinz

    2018-06-01

    We present broadband polarimetric observations of a sample of high-Faraday-rotation-measure (high-RM) active galactic nuclei (AGN) using the Karl. G. Jansky Very Large Array (JVLA) telescope from 1 to 2 GHz, and 4 to 12 GHz. The sample (14 sources) consists of very compact sources (linear resolution smaller than ≈5 kpc) that are unpolarized at 1.4 GHz in the NRAO VLA Sky Survey (NVSS). Total intensity data have been modeled using a combination of synchrotron components, revealing complex structure in their radio spectra. Depolarization modeling, through the so-called qu-fitting (the modeling of the fractional quantities of the Stokes Q and U parameters), has been performed on the polarized data using an equation that attempts to simplify the process of fitting many different depolarization models. These models can be divided into two major categories: external depolarization (ED) and internal depolarization (ID) models. Understanding which of the two mechanisms is the most representative would help the qualitative understanding of the AGN jet environment and whether it is embedded in a dense external magneto-ionic medium or if it is the jet-wind that causes the high RM and strong depolarization. This could help to probe the jet magnetic field geometry (e.g., helical or otherwise). This new high-sensitivity data shows a complicated behavior in the total intensity and polarization radio spectrum of individual sources. We observed the presence of several synchrotron components and Faraday components in their total intensity and polarized spectra. For the majority of our targets (12 sources), the depolarization seems to be caused by a turbulent magnetic field. Thus, our main selection criteria (lack of polarization at 1.4 GHz in the NVSS) result in a sample of sources with very large RMs and depolarization due to turbulent magnetic fields local to the source. These broadband JVLA data reveal the complexity of the polarization properties of this class of radio sources

  9. Nuclear polarization and neutrons

    International Nuclear Information System (INIS)

    Glaettli, H.

    1985-01-01

    Different possibilities for the use of polarized nuclei in thermal neutron scattering on condensed matter are reviewed. Highly polarized nuclei are the starting point for studying dipolar magnetic order. Systematic measurement of spin-dependent scattering lengths is possible on samples with polarized nuclei. Highly polarized hydrogen should help to unravel complicated structures in chemistry and biology. The use of polarized proton targets as an energy-independent neutron polarizer in the thermal and epithermal region should be considered afresh. (author)

  10. Broadband Optical Access Technologies to Converge towards a Broadband Society in Europe

    Science.gov (United States)

    Coudreuse, Jean-Pierre; Pautonnier, Sophie; Lavillonnière, Eric; Didierjean, Sylvain; Hilt, Benoît; Kida, Toshimichi; Oshima, Kazuyoshi

    This paper provides insights on the status of broadband optical access market and technologies in Europe and on the expected trends for the next generation optical access networks. The final target for most operators, cities or any other player is of course FTTH (Fibre To The Home) deployment although we can expect intermediate steps with copper or wireless technologies. Among the two candidate architectures for FTTH, PON (Passive Optical Network) is by far the most attractive and cost effective solution. We also demonstrate that Ethernet based optical access network is very adequate to all-IP networks without any incidence on the level of quality of service. Finally, we provide feedback from a FTTH pilot network in Colmar (France) based on Gigabit Ethernet PON technology. The interest of this pilot lies on the level of functionality required for broadband optical access networks but also on the development of new home network configurations.

  11. High efficiency and broadband acoustic diodes

    Science.gov (United States)

    Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

    2018-01-01

    Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

  12. Frequency Doubling Broadband Light in Multiple Crystals

    International Nuclear Information System (INIS)

    Alford, William J.; Smith, Arlee V.

    2000-01-01

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth

  13. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua

    2013-04-25

    Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range. © 2013 IOP Publishing Ltd.

  14. Piezoelectric energy harvesting from broadband random vibrations

    International Nuclear Information System (INIS)

    Adhikari, S; Friswell, M I; Inman, D J

    2009-01-01

    Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples

  15. Piezoelectric energy harvesting from broadband random vibrations

    Science.gov (United States)

    Adhikari, S.; Friswell, M. I.; Inman, D. J.

    2009-11-01

    Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples.

  16. Techno-Economics of Residential Broadband Deployment

    DEFF Research Database (Denmark)

    Sigurdsson, Halldor Matthias

    2007-01-01

    on account of their existing telecom network (”the raw copper”), and typically they will prefer an xDSL-based strategy (various types of Digital Subscriber Line-technology: ADSL, VDSL, etc.), where the rate of speed of data connections are increased gradually to 10-50 Mbit/s or even more, in order to gain...... broadband deployment strategy is depending on a complexed set of parameters, and there is a demand for precise techno-economic cost models estimating financial feasibility. The existing cost models do not consider the dynamic developments in the market caused by competition. The PhD thesis has a profound...... the general principles from the Danish LRAIC-model (Long Run Average Incremental Cost) and divides Denmark in 4 geografical profiles. Considering the existing copper-infrastructure the most advantageous strategies for the players of each of these profiles are identified. The importance of the time horizon...

  17. Broadband plasmon induced transparency in terahertz metamaterials

    International Nuclear Information System (INIS)

    Zhu Zhihua; Yang Xu; Gu Jianqiang; Jiang Jun; Tian Zhen; Han Jiaguang; Zhang Weili; Yue Weisheng; Tonouchi, Masayoshi

    2013-01-01

    Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range. (paper)

  18. QCD on the Cell Broadband Engine

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Nils [Department of Physics, University of Regensburg, 93040 Regensburg (Germany)

    2008-07-01

    We evaluate IBM's Enhanced Cell Broadband Engine (BE) as a possible building block of a new generation of lattice QCD machines. The Enhanced Cell BE will provide full support of double precision floating-point arithmetics, including IEEE-compliant rounding. We have developed a performance model and applied it to relevant lattice QCD kernels. The performance estimates are supported by micro- and application-benchmarks that have been obtained on currently available Cell BE-based computers, such as IBM QS20 blades and PlayStation 3. The results are encouraging and show that this processor is an interesting option for lattice QCD applications. For a massively parallel machine on the basis of the Cell BE, an application-optimized network needs to be developed.

  19. QCD on the Cell Broadband Engine

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Nils [Department of Physics, University of Regensburg, 93040 Regensburg (Germany)

    2008-07-01

    We evaluate IBM's Enhanced Cell Broadband Engine (BE) as a possible building block of a new generation of lattice QCD machines. The Enhanced Cell BE will provide full support of double precision floating-point arithmetics, including IEEE-compliant rounding. We have developed a performance model and applied it to relevant lattice QCD kernels. The performance estimates are supported by micro- and application-benchmarks that have been obtained on currently available Cell BE-based computers, such as IBM QS20 blades and PlayStation 3. The results are encouraging and show that this processor is an interesting option for lattice QCD applications. For a massively parallel machine on the basis of the Cell BE, an application-optimized network needs to be developed.

  20. Patient portals and broadband internet inequality.

    Science.gov (United States)

    Perzynski, Adam T; Roach, Mary Joan; Shick, Sarah; Callahan, Bill; Gunzler, Douglas; Cebul, Randall; Kaelber, David C; Huml, Anne; Thornton, John Daryl; Einstadter, Douglas

    2017-09-01

    Patient portals have shown potential for increasing health care quality and efficiency. Internet access and other factors influencing patient portal use could worsen health disparities. Observational study of adults with 1 or more visits to the outpatient clinics of an urban public health care system from 2012 to 2015. We used mixed effects logistic regression to evaluate the association between broadband internet access and (1) patient portal initiation (whether a patient logged in at least 1 time) and (2) messaging, controlling for demographic and neighborhood characteristics. There were 243 248 adults with 1 or more visits during 2012-2015 and 70 835 (29.1%) initiated portal use. Portal initiation was 34.1% for whites, 23.4% for blacks, and 23.8% for Hispanics, and was lower for Medicaid (26.5%), Medicare (23.4%), and uninsured patients (17.4%) than commercially insured patients (39.3%). In multivariate analysis, both initiation of portal use (odds ratio [OR] = 1.24 per quintile, 95% confidence interval [CI], 1.23-1.24, P  internet access. The majority of adults with outpatient visits to a large urban health care system did not use the patient portal, and initiation of use was lower for racial and ethnic minorities, persons of lower socioeconomic status, and those without neighborhood broadband internet access. These results suggest the emergence of a digital divide in patient portal use. Given the scale of investment in patient portals and other internet-dependent health information technologies, efforts are urgently needed to address this growing inequality. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  1. Neutron polarization in polarized 3He targets

    International Nuclear Information System (INIS)

    Friar, J.L.; Gibson, B.F.; Payne, G.L.; Bernstein, A.M.; Chupp, T.E.

    1990-01-01

    Simple formulas for the neutron and proton polarizations in polarized 3 He targets are derived assuming (1) quasielastic final states; (2) no final-state interactions; (3) no meson-exchange currents; (4) large momentum transfers; (5) factorizability of 3 He SU(4) response-function components. Numerical results from a wide variety of bound-state solutions of the Faddeev equations are presented. It is found that this simple model predicts the polarization of neutrons in a fully polarized 3 He target to be 87%, while protons should have a slight residual polarization of -2.7%. Numerical studies show that this model works very well for quasielastic electron scattering

  2. Metropolitan area networks: a corner stone in the broadband era

    Science.gov (United States)

    Ghanem, Adel

    1991-02-01

    Deployment of Broadband ISDN is being influenced by both a market pull and a technology push. New broadband service opportunities exist in the business and residential sectors of the market place. It is envisioned that some customers will need connections directly to broadband switches because of the high bandwidth needed for their applications. At the same time Metropolitan Area Network (MAN) systems will serve those customers with bandwidth requirements less than or equal to 150 Mbps. A given MAN will have a geographical domain to serve where it will carry out the switching tasks within this domain. While MANs couldbe designed using differentarchitecturalconcepts the setofservices expected tobeprovidedby MANs could be equivalent to thelist ofservices thatwillbe supported by the targetbroadband network. This paperpositions MANs as a major building block for Broadband networks. It also examines the evolution process ofMANs as a needed step to assure the successful deployment of these new broadband services. 2. BISDN - OVERVIEW Broadband ISDN (BISDN) is being driven into existence by both a market pull as well as a technology push. Opportunities for new valueadded services are the prime market pull for future broadband networks. These services opportunities extend beyond simple voice and low speed data applications and cover both the residential and the business sectors of the market. It is noted for instance that business customers have growing needs for sophisticated telecommunication vehicles to support their

  3. Broadband availability in metropolitan and non-metropolitan Pennsylvania

    Directory of Open Access Journals (Sweden)

    Lawrence E. Wood

    2016-09-01

    Full Text Available Over the past few years having a broadband connection has become essential for many Internet activities. As broadband increases in importance, it becomes imperative to assess how its use and availability may vary, especially in relation to issues such as geographic location. For rural areas in particular, the availability of broadband service is especially important. This research assesses broadband service availability in rural areas of Pennsylvania, USA. In particular, it examines the extent to which Digital Subscriber Line (DSL and broadband cable modem services are being deployed throughout rural Pennsylvania. It compares this deployment with the availability of such services in the state’s urban and metropolitan areas. The results of this research suggest that there is a “digital divide” in terms of broadband availability between rural and urban areas of Pennsylvania. However, this “divide” is perhaps not as wide as might be expected. Thus, as broadband is becoming increasingly available in rural areas of the U.S. and throughout much of the rest of the world, this research concludes that while research must remain vigilant in terms of assessing advanced telecommunications availability in rural areas, future research should also be sure to focus on how such technologies can be used to promote economic and social concerns, including in relation to building online networks and diminishing social and professional isolation in rural areas.

  4. Detailed analysis of evolution of the state of polarization in all-fiber polarization transformers.

    Science.gov (United States)

    Zhu, Xiushan; Jain, Ravinder K

    2006-10-30

    We present a detailed analysis of key attributes and performance characteristics of controllably-spun birefringent-fiber-based all-fiber waveplates or "all fiber polarization transformers" (AFPTs), first proposed and demonstrated by Huang [11]; these AFPTs consist essentially of a long carefully-designed "spin-twisted" high-birefringence fiber, fabricated by slowly varying the spin rate of a birefringent fiber preform (either from very fast to very slow or vice versa) while the fiber is being drawn. The evolution of the eigenstate from a linear polarization state to a circular polarization state, induced by slow variation of the intrinsic structure from linear anisotropy at the unspun end to circular anisotropy at the fast-spun end, enables the AFPT to behave like an all-fiber quarter-wave plate independent of the wavelength of operation. Power coupling between local eigenstates causes unique evolution of the polarization state along the fiber, and has been studied to gain insight into - as well as to understand detailed characteristics of -- the polarization transformation behavior. This has been graphically illustrated via plots of the relative power in these local eigenstates as a function of distance along the length of the fiber and plots of the extinction ratio of the output state of polarization (SOP) as a function of distance and the normalized spin rate. Deeper understanding of such polarization transformers has been further elucidated by quantitative calculations related to two crucial requirements for fabricating practical AFPT devices. Our calculations have also indicated that the polarization mode dispersion behaviour of the AFPT is much smaller than that of the original birefringent fiber. Finally, a specific AFPT was experimentally investigated at two widely-separated wavelengths (1310 nm and 1550 nm) of interest in telecommunications systems applications, further demonstrating and elucidating the broadband character of such AFPTs.

  5. Broadband infrared beam splitter for spaceborne interferometric infrared sounder.

    Science.gov (United States)

    Yu, Tianyan; Liu, Dingquan; Qin, Yang

    2014-10-01

    A broadband infrared beam splitter (BS) on ZnSe substrate used for the spaceborne interferometric infrared sounder (SIIRS) is studied in the spectral range of 4.44-15 μm. Both broadband antireflection coating and broadband beam-splitter coating in this BS are designed and tested. To optimize the optical properties and the stability of the BS, suitable infrared materials were selected, and improved deposition techniques were applied. The designed structures matched experimental data well, and the properties of the BS met the application specification of SIIRS.

  6. Polarized electron sources

    International Nuclear Information System (INIS)

    Prepost, R.

    1994-01-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented

  7. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  8. Metallic metasurfaces for high efficient polarization conversion control in transmission mode.

    Science.gov (United States)

    Li, Tong; Hu, Xiaobin; Chen, Huamin; Zhao, Chen; Xu, Yun; Wei, Xin; Song, Guofeng

    2017-10-02

    A high efficient broadband polarization converter is an important component in integrated miniaturized optical systems, but its performances is often restricted by the material structures, metallic metasurfaces for polarization control in transmission mode never achieved efficiency above 0.5. Herein, we theoretically demonstrate that metallic metasurfaces constructed by thick cross-shaped particles can realize a high efficient polarization transformation over a broadband. We investigated the resonant properties of designed matesurfaces and found that the interaction between double FP cavity resonances and double bulk magnetic resonances is the main reason to generate a high transmissivity over a broadband. In addition, through using four resonances effect and tuning the anisotropic optical response, we realized a high efficient (> 0.85) quarter-wave plate at the wavelength range from 1175nm to 1310nm and a high efficient (> 0.9) half-wave plate at the wavelength range from 1130nm to 1230nm. The proposed polarization converters may have many potential applications in integrated polarization conversion devices and optical data storage systems.

  9. Polarized neutron spectrometer

    International Nuclear Information System (INIS)

    Abov, Yu.G.; Novitskij, V.V.; Alfimenkov, V.P.; Galinskij, E.M.; Mareev, Yu.D.; Pikel'ner, L.B.; Chernikov, A.N.; Lason', L.; Tsulaya, V.M.; Tsulaya, M.I.

    2000-01-01

    The polarized neutron spectrometer, intended for studying the interaction of polarized neutrons with nuclei and condensed media in the area of energies from thermal up to several electron-volt, is developed at the IBR-2 reactor (JINR, Dubna). Diffraction on the Co(92%)-Fe(8%) magnetized monocrystals is used for the neutron polarization and polarization analysis. The neutron polarization within the whole energy range equals ∼ 95% [ru

  10. Conversion of broadband IR radiation and structural disorder in lithium niobate single crystals with low photorefractive effect

    Science.gov (United States)

    Litvinova, Man Nen; Syuy, Alexander V.; Krishtop, Victor V.; Pogodina, Veronika A.; Ponomarchuk, Yulia V.; Sidorov, Nikolay V.; Gabain, Aleksei A.; Palatnikov, Mikhail N.; Litvinov, Vladimir A.

    2016-11-01

    The conversion of broadband IR radiation when the noncritical phase matching condition is fulfilled in lithium niobate (LiNbO3) single crystals with stoichiometric (R = Li/Nb = 1) and congruent (R = 0.946) compositions, as well as in congruent single crystals doped with zinc has been investigated. It is shown that the spectrum parameters of converted radiation, such as the conversion efficiency, spectral width and position of maximum, depend on the ordering degree of structural units of the cation sublattice along the polar axis of crystal.

  11. Interest in broadband dielectric spectroscopy to study the electronic transport in materials for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Badot, Jean-Claude, E-mail: jc.badot@chimie-paristech.fr [Institut de Recherche de Chimie Paris, UMR CNRS 8247, Réseau sur le Stockage Electrochimique de l' Energie (RS2E), Chimie Paris Tech, PSL*, 11 rue P. et M. Curie, 75231 Cedex 05 Paris (France); Lestriez, Bernard [Institut des Matériaux Jean Rouxel, UMR CNRS 6502, Université de Nantes, 2 rue de la Houssinière, BP32229, 44322 Nantes (France); Dubrunfaut, Olivier [GeePs | Group of electrical engineering – Paris, UMR CNRS 8507, CentraleSupélec, Univ. Paris-Sud, Université Paris-Saclay, Sorbonne Universités, UPMC Univ Paris 06, 3 & 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette CEDEX, Paris (France)

    2016-11-15

    Highlights: • Broadband dielectric spectroscopy measures the multiscale electronic conductivity from macroscopic to interatomic sizes. • There is an influence of the surface states on the electronic transfer of powdered materials (e.g. thin insulating layer of Li{sub 2}CO{sub 3} on LiNiO{sub 2} and carbon coating on LiFePO{sub 4}). • Electrical relaxations resulting from the interfacial polarizations at the different scales of the carbon black network are evidenced. - Abstract: Broadband dielectric spectroscopy (BDS) is used to measure complex permittivity and conductivity of conducting materials for lithium batteries at frequencies from a few Hz to several GHz with network and impedance analysers. Under the influence of an electric field, there will be charge density fluctuations in the conductor mainly due to electronic transfer. These fluctuations result in dielectric relaxations for frequencies below 100 GHz. The materials are compacted powders in which each element (particles, agglomerates of particles) can have different sizes and morphologies. In the present review, studies are reported on the influence of surface states in LiNiO{sub 2} (ageing and degradation in air) and LiFePO{sub 4} (carbon coating thin layer), and on a composite electrode based on the lithium trivanadate (Li{sub 1.1}V{sub 3}O{sub 8}) active material. The results have shown that the BDS technique is very sensitive to the different scales of materials architectures involved in electronic transport, from interatomic distances to macroscopic sizes.

  12. A broadband metamaterial absorber based on multi-layer graphene in the terahertz region

    Science.gov (United States)

    Fu, Pan; Liu, Fei; Ren, Guang Jun; Su, Fei; Li, Dong; Yao, Jian Quan

    2018-06-01

    A broadband metamaterial absorber, composed of the periodic graphene pattern on SiO2 dielectric with the double layer graphene films inserted in it and all of them backed by metal plan, is proposed and investigated. The simulation results reveal that the wide absorption band can be flexibly tuned between the low-frequency band and the high-frequency band by adjusting graphene's Fermi level. The absorption can achieve 90% in 5.50-7.10 THz, with Fermi level of graphene is 0.3 eV, while in 6.98-9.10 THz with Fermi level 0.6 eV. Furthermore, the proposed structure can be switched from reflection (>81%) to absorption (>90%) over the whole operation band, when the Fermi level of graphene varies from 0 to 0.6 eV. Besides, the proposed absorber is insensitive to the polarization and can work over a wide range of incident angle. Compared with the previous broadband absorber, our graphene based wideband terahertz absorber can enable a wide application of high performance terahertz devices, including sensors, imaging devices and electro-optic switches.

  13. The development and characterization of advanced broadband mirror coatings for the far-UV

    Science.gov (United States)

    Egan, Arika; Fleming, Brian T.; Wiley, James; Quijada, Manuel; Del Hoyo, Javier; Hennessy, John; Hicks, Brian; France, Kevin; Kruczek, Nicholas; Erickson, Nicholas

    2017-08-01

    We present a progress report on the development of new broadband mirror coatings that demonstrate > 80% reflectivities from 1020-5000Å. Four different coating recipes are presented as candidates for future far-ultraviolet (FUV) sensitive broadband observatories. Three samples were first coated with aluminum (Al) and lithium fluoride (LiF) at the NASA Goddard Space Flight Center (GSFC) using a new high-temperature physical vapor deposition (PVD) process. Two of these samples then had an ultrathin (10-20 Å) protective coat of either magnesium fluoride (MgF2) or aluminum fluoride (AlF3) applied using atomic later deposition (ALD) at the NASA Jet Propulsion Laboratory (JPL). A fourth sample was coated with Al and a similar high temperature PVD coating of AlF3. Polarized reflectivities into the FUV for each sample were obtained through collaboration with the Synchrotron Ultraviolet Radiation Facility at the National Institute of Standards and Technology. We present a procedure for using these reflectivities as a baseline for calculating the optical constants of each coating recipe. Given these results, we describe plans for improving our measurement methodology and techniques to develop and characterize these coating recipes for future FUV missions.

  14. Broadband and wide angle near-unity absorption in graphene-insulator-metal thin film stacks

    Science.gov (United States)

    Zhang, H. J.; Zheng, G. G.; Chen, Y. Y.; Xu, L. H.

    2018-05-01

    Broadband unity absorption in graphene-insulator-metal (GIM) structures is demonstrated in the visible (VIS) and near-infrared (NIR) spectra. The spectral characteristics possess broadband absorption peaks, by simply choosing a stack of GIM, while no nanofabrication steps and patterning are required, and thus can be easily fabricated to cover a large area. The electromagnetic (EM) waves can be entirely trapped and the absorption can be greatly enhanced are verified with the finite-difference time-domain (FDTD) and rigorous coupled wave analysis (RCWA) methods. The position and the number of the absorption peak can be totally controlled by adjusting the thickness of the insulator layer. The proposed absorber maintains high absorption (above 90%) for both transverse electric (TE) and transverse magnetic (TM) polarizations, and for angles of incidence up to 80°. This work opens up a promising approach to realize perfect absorption (PA) with ultra-thin film, which could implicate many potential applications in optical detection and optoelectronic devices.

  15. Interest in broadband dielectric spectroscopy to study the electronic transport in materials for lithium batteries

    International Nuclear Information System (INIS)

    Badot, Jean-Claude; Lestriez, Bernard; Dubrunfaut, Olivier

    2016-01-01

    Highlights: • Broadband dielectric spectroscopy measures the multiscale electronic conductivity from macroscopic to interatomic sizes. • There is an influence of the surface states on the electronic transfer of powdered materials (e.g. thin insulating layer of Li_2CO_3 on LiNiO_2 and carbon coating on LiFePO_4). • Electrical relaxations resulting from the interfacial polarizations at the different scales of the carbon black network are evidenced. - Abstract: Broadband dielectric spectroscopy (BDS) is used to measure complex permittivity and conductivity of conducting materials for lithium batteries at frequencies from a few Hz to several GHz with network and impedance analysers. Under the influence of an electric field, there will be charge density fluctuations in the conductor mainly due to electronic transfer. These fluctuations result in dielectric relaxations for frequencies below 100 GHz. The materials are compacted powders in which each element (particles, agglomerates of particles) can have different sizes and morphologies. In the present review, studies are reported on the influence of surface states in LiNiO_2 (ageing and degradation in air) and LiFePO_4 (carbon coating thin layer), and on a composite electrode based on the lithium trivanadate (Li_1_._1V_3O_8) active material. The results have shown that the BDS technique is very sensitive to the different scales of materials architectures involved in electronic transport, from interatomic distances to macroscopic sizes.

  16. BROADBAND RADIO POLARIMETRY AND FARADAY ROTATION OF 563 EXTRAGALACTIC RADIO SOURCES

    International Nuclear Information System (INIS)

    Anderson, C. S.; Gaensler, B. M.; Feain, I. J.; Franzen, T. M. O.

    2015-01-01

    We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the presence of material possessing complicated magnetoionic structure along the line of sight (LOS). For sources classified as Faraday-complex, we have analyzed a number of their radio and multiwavelength properties to determine whether they differ from Faraday-simple polarized sources (sources for which LOS magnetoionic structures are comparatively simple) in these properties. We use this information to constrain the physical nature of the magnetoionic structures responsible for generating the observed complexity. We detect Faraday complexity in 12% of polarized sources at ∼1′ resolution, but we demonstrate that underlying signal-to-noise limitations mean the true percentage is likely to be significantly higher in the polarized radio source population. We find that the properties of Faraday-complex objects are diverse, but that complexity is most often associated with depolarization of extended radio sources possessing a relatively steep total intensity spectrum. We find an association between Faraday complexity and LOS structure in the Galactic interstellar medium (ISM) and claim that a significant proportion of the Faraday complexity we observe may be generated at interfaces of the ISM associated with ionization fronts near neutral hydrogen structures. Galaxy cluster environments and internally generated Faraday complexity provide possible alternative explanations in some cases

  17. Broadband back grating design for thin film solar cells

    KAUST Repository

    Janjua, Bilal; Jabbour, Ghassan E.

    2013-01-01

    In this paper, design based on tapered circular grating structure was studied, to provide broadband enhancement in thin film amorphous silicon solar cells. In comparison to planar structure an absorption enhancement of ~ 7% was realized.

  18. Fixed Broadband Deployment Data: June, 2016 Status V1

    Data.gov (United States)

    Federal Communications Commission — Version 1 reflects data filed by the March 1, 2016 filing deadline and any revisions made before February 10, 2017. All facilities-based broadband providers are...

  19. Broadband Reflective Coating Process for Large FUVOIR Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ZeCoat Corporation will develop and demonstrate a set of revolutionary coating processes for making broadband reflective coatings suitable for very large mirrors (4+...

  20. Direct and quantitative broadband absorptance spectroscopy with multilayer cantilever probes

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan Kien-Kwok; Liao, Bolin; Chen, Gang

    2015-04-21

    A system for measuring the absorption spectrum of a sample is provided that includes a broadband light source that produces broadband light defined within a range of an absorptance spectrum. An interferometer modulates the intensity of the broadband light source for a range of modulation frequencies. A bi-layer cantilever probe arm is thermally connected to a sample arm having at most two layers of materials. The broadband light modulated by the interferometer is directed towards the sample and absorbed by the sample and converted into heat, which causes a temperature rise and bending of the bi-layer cantilever probe arm. A detector mechanism measures and records the deflection of the probe arm so as to obtain the absorptance spectrum of the sample.

  1. Fixed Broadband Deployment Data: June, 2016 Status V2

    Data.gov (United States)

    Federal Communications Commission — This data contains status reports for June 2016, with revisions accepted through May 2017. All facilities-based broadband providers are required to file data with...

  2. Expressive Communication and Human Development in the New Broadband Environment

    Science.gov (United States)

    Carey, John

    2004-01-01

    An understanding of the structure and functions of expressive communication in face-to-face communication and audiovisual media can inform the development of new educational services for human development across cultures in the emerging broadband environment.

  3. Broadband Wireless Data Acquisition and Control Device, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobitrum is proposing to develop a broadband wireless device for real-time data acquisition and monitoring applicable to the field instrumentation and control...

  4. 76 FR 13769 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2011-03-14

    ... pharmacy work, and savings to health facilities from outsourcing specialized medical procedures. One study... international markets and enables new, small, and home-based businesses to thrive. Broadband access affords...

  5. 78 FR 8353 - Rural Broadband Access Loans and Loan Guarantees

    Science.gov (United States)

    2013-02-06

    ... outsourcing specialized medical procedures. One study of 24 rural hospitals placed the annual cost of not... a key to economic growth. For rural businesses, broadband gives access to national and international...

  6. Broadband and High power Reactive Jamming Resilient Wireless Communication

    Science.gov (United States)

    2017-10-21

    Broadband and High -power Reactive Jamming Resilient Wireless Communication The views, opinions and/or findings contained in this report are those of... available in extremely hostile environments, where FHSS and DSSS are completely defeated by a broadband and high -power reactive jammer. b. Wireless...SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS

  7. Crosstalk analysis of a broadband data communications system

    Science.gov (United States)

    Crutcher, R. I.; Ewing, P. D.; Hayes, T. W.

    1987-11-01

    A broadband cable system represents a significant resource for data transmission within a facility. Duplication of a broadband network to provide services of varying sensitivity levels within the same area is wasteful of capital resources. The sharing of a network by different data services is financially attractive providing that sensitive data are inaccessible from nonsensitive ports. The use of equipment from two manufacturers introduces a deliberate incompatibility for the purpose of data isolation. This report presents test results obtained by this technique.

  8. A high extinction ratio THz polarizer fabricated by double-bilayer wire grid structure

    Directory of Open Access Journals (Sweden)

    Bin Lu

    2016-02-01

    Full Text Available We designed a new style of broadband terahertz (THz polarizer with double-bilayer wire grid structure by fabricating them on both sides of silicon substrate. This THz polarizer shows a high average extinction ratio of 60dB in 0.5 to 2.0 THz frequency range and the maximum of 87 dB at 1.06 THz, which is much higher than that of conventional monolayer wire grid polarizers and single-bilayer wire grid ones.

  9. Polarized (3) He Spin Filters for Slow Neutron Physics.

    Science.gov (United States)

    Gentile, T R; Chen, W C; Jones, G L; Babcock, E; Walker, T G

    2005-01-01

    Polarized (3)He spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation coefficient measurements. In addition, they are broadband devices that can polarize large area and high divergence neutron beams with little gamma-ray background, and allow for an additional spin-flip for systematic tests. These attributes are relevant to all neutron sources, but are particularly well-matched to time of flight analysis at spallation sources. There are several issues in the practical use of (3)He spin filters for slow neutron physics. Besides the essential goal of maximizing the (3)He polarization, we also seek to decrease the constraints on cell lifetimes and magnetic field homogeneity. In addition, cells with highly uniform gas thickness are required to produce the spatially uniform neutron polarization needed for beta-decay correlation coefficient experiments. We are currently employing spin-exchange (SE) and metastability-exchange (ME) optical pumping to polarize (3)He, but will focus on SE. We will discuss the recent demonstration of 75 % (3)He polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping.

  10. Ultra-broadband THz time-domain spectroscopy of common polymers using THz air photonics

    DEFF Research Database (Denmark)

    D’Angelo, Francesco; Mics, Zoltán; Bonn, Mischa

    2014-01-01

    -domain spectrometer employing air-photonics for the generation and detection of single-cycle sub-50 fs THz transients. The time domain measurements provide direct access to both the absorption and refractive index spectra. The polymers LDPE and TOPAS® demonstrate negligible absorption and spectrally-flat refractive...... index across the entire spectroscopy window, revealing the high potential of these polymers for applications in THz photonics such as ultra-broadband polymer-based dielectric mirrors, waveguides, and fibers. Resonant high-frequency polar vibrational modes are observed and assigned in polymers PA6...... and PTFE, and their dielectric functions in the complete frequency window 2-15 THz are theoretically reproduced. Our results demonstrate the potential of ultrabroadband air-photonics-based THz time domain spectroscopy as a valuable analytic tool for materials science....

  11. Cluster observations and theoretical identification of broadband waves in the auroral region

    Directory of Open Access Journals (Sweden)

    M. Backrud-Ivgren

    2005-12-01

    Full Text Available Broadband waves are common on auroral field lines. We use two different methods to study the polarization of the waves at 10 to 180 Hz observed by the Cluster spacecraft at altitudes of about 4 Earth radii in the nightside auroral region. Observations of electric and magnetic wave fields, together with electron and ion data, are used as input to the methods. We find that much of the wave emissions are consistent with linear waves in homogeneous plasma. Observed waves with a large electric field perpendicular to the geomagnetic field are more common (electrostatic ion cyclotron waves, while ion acoustic waves with a large parallel electric field appear in smaller regions without suprathermal (tens of eV plasma. The regions void of suprathermal plasma are interpreted as parallel potential drops of a few hundred volts.

  12. How to adapt broad-band gravitational-wave searches for r-modes

    International Nuclear Information System (INIS)

    Owen, Benjamin J.

    2010-01-01

    Up to now there has been no search for gravitational waves from the r-modes of neutron stars in spite of the theoretical interest in the subject. Several oddities of r-modes must be addressed to obtain an observational result: The gravitational radiation field is dominated by the mass current (gravitomagnetic) quadrupole rather than the usual mass quadrupole, and the consequent difference in polarization affects detection statistics and parameter estimation. To astrophysically interpret a detection or upper limit it is necessary to convert the gravitational-wave amplitude to an r-mode amplitude. Also, it is helpful to know indirect limits on gravitational-wave emission to gauge the interest of various searches. Here I address these issues, thereby providing the ingredients to adapt broad-band searches for continuous gravitational waves to obtain r-mode results. I also show that searches of existing data can already have interesting sensitivities to r-modes.

  13. Broadband one-dimensional photonic crystal wave plate containing single-negative materials.

    Science.gov (United States)

    Chen, Yihang

    2010-09-13

    The properties of the phase shift of wave reflected from one-dimensional photonic crystals consisting of periodic layers of single-negative (permittivity- or permeability-negative) materials are demonstrated. As the incident angle increases, the reflection phase shift of TE wave decreases, while that of TM wave increases. The phase shifts of both polarized waves vary smoothly as the frequency changes across the photonic crystal stop band. Consequently, the difference between the phase shift of TE and that of TM wave could remain constant in a rather wide frequency range inside the stop band. These properties are useful to design wave plate or retarder which can be used in wide spectral band. In addition, a broadband photonic crystal quarter-wave plate is proposed.

  14. Frequency-dependent absorbance of broadband terahertz wave in dense plasma sheet

    Science.gov (United States)

    Peng, Yan; Qi, Binbin; Jiang, Xiankai; Zhu, Zhi; Zhao, Hongwei; Zhu, Yiming

    2018-05-01

    Due to the ability of accurate fingerprinting and low-ionization for different substances, terahertz (THz) technology has a lot of crucial applications in material analysis, information transfer, and safety inspection, etc. However, the spectral characteristic of atmospheric gas and ionized gas has not been widely investigated, which is important for the remote sensing application. Here, in this paper, we investigate the absorbance of broadband terahertz wave in dense plasma sheet generated by femtosecond laser pulses. It was found that as the terahertz wave transmits through the plasma sheet formed, respectively, in carbon dioxide, oxygen, argon and nitrogen, spectrum presents completely different and frequency-dependent absorbance. The reasons for these absorption peaks are related to the molecular polarity, electric charge, intermolecular and intramolecular interactions, and collisional absorption of gas molecules. These results have significant implications for the remote sensing of gas medium.

  15. Investigating broadband acoustic adsorption using rapid manufacturing

    Science.gov (United States)

    Godbold, O.

    The reduction of nuisance noise and the removal of unwanted sound modes within a room or component enclosure-area can be accomplished through the use of acoustic absorbers. Sound absorption can be achieved through conversion of the kinetic energy associated with pressure waves, into heat energy via viscous dissipation. This occurs within open porous materials, or by utilising resonant effects produced using simple cavity and orifice configurations. The manufacture of traditional porous and resonant absorbers is commonly realised using basic manufacturing techniques. These techniques restrict the geometry of a given resonant construction, and limit the configuration of porous absorbers. The aim of this work is to exploit new and emerging capabilities of Rapid Manufacturing (RM) to produce components with geometrical freedom, and apply it to the development of broadband acoustic absorption. New and novel absorber geometric configurations are identified and their absorption performance is determined. The capabilities and limitations of RM processes in reproducing these configurations are demonstrated. The geometric configuration of RM resonant absorbers is investigated. Cavity modifications aimed at damping the resonant effect by restricting the motion of cavity air, and adding increased viscous resistance are explored. Modifications relating to cavity shape, the addition of internal perforations and increased cavity surface area have all been shown to add acoustic resistance, thereby increasing the bandwidth of absorption. Decreasing the hydraulic radius of the cavity cross section and reducing internal feature dimensions provide improved resistance over conventional configurations..

  16. Broadband spectrally dynamic solid state illumination source

    Energy Technology Data Exchange (ETDEWEB)

    Nicol, David B; Asghar, Ali; Gupta, Shalini; Kang, Hun; Pan, Ming [Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, GA 30332-0250 (United States); Strassburg, Martin [Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, GA 30332-0250 (United States); Georgia State University, Department of Physics and Astronomy, Atlanta, GA 30302-4106 (United States); Summers, Chris; Ferguson, Ian T [Georgia Institute of Technology, School of Materials Science and Engineering, Atlanta, GA 30332 (United States)

    2006-06-15

    Solid state lighting has done well recently in niche markets such as signage and displays, however, no available SSL technologies incorporate all the necessary attributes for general illumination. Development of a novel solid state general illumination source is discussed here. Two LEDs emitting at two distinct wavelengths can be monolithically grown and used to excite two or more phosphors with varied excitation spectra. The combined phosphorescence spectrum can then be controlled by adjusting the relative intensities of the two LED emissions. Preliminary phosphor analysis shows such a scheme to be viable for use in a spectrally dynamic broadband general illumination source. A tunnel junction is envisioned as a means of current spreading in a buried layer for three terminal operation. However, tunnel junction properties in GaN based materials are not well understood, and require further optimization to be practical devices. Preliminary results on GaN tunnel junctions are presented here as well. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Broadband over powerline : advances and applications

    Energy Technology Data Exchange (ETDEWEB)

    Gunther, E.W. [EnerNex Corp., Knoxville, TN (United States)

    2006-07-01

    An overview of the broadband over powerline (BPL) industry was presented with reference to the history of the technology; current trials and deployments; applications; and, technologies currently in service. The presentation offers background information and a history of BPL, an early adopters test lab, BPL deployment map and access BPL stats. A comparison of wireless, hybrid and fiber optic communication technologies was presented along with access BPL systems and a review of how BPL can enhance utility operations. Diagnostic monitoring, operations improvement, system protection, load and DG management, distribution automation, and customer interface were included in an eye chart for operations enhancement. Suggestions on how BPL can reduce distribution line radio interference were presented along with examples of how BPL EMI analysis can find faulty electrical equipment. BPL customer services include Internet access, consumer portal, voice over Internet protocol, video surveillance, video conferencing, and building automation and energy management. BPL technical issues include installation, operation and electromagnetic compatibility. BPL regulations and standard efforts were described. It was concluded that BPL has a variety of applications in the utility sector including power quality, reliability monitoring and improvement. 1 tab., 7 figs.

  18. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  19. Silicon Micromachined Sensor for Broadband Vibration Analysis

    Science.gov (United States)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  20. Broadband Ionospheric Scintillation Measurements from Space

    Science.gov (United States)

    Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

    2014-12-01

    The U.S. Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 825 - 1100 MHz. In this paper, we present an overview of the RFProp on-orbit research and analysis effort with particular focus on an equatorial scintillation experiment called ESCINT. The 3-year ESCINT project is designed to characterize equatorial ionospheric scintillation in the upper HF and lower VHF portions of the radio spectrum (20 - 150 MHz). Both a 40 MHz continuous wave (CW) signal and 30 - 42 MHz swept frequency signal are transmitted to the satellite receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in four separate campaigns centered on the 2014 and 2015 equinoxes. Results from the first campaign conducted from April 22 - May 15, 2014 will be presented including (a) coherence bandwidth measurements over a full range of transmission frequencies and scintillation activity levels, (b) spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities, and (c) supporting ray-trace simulations. The broadband nature of the measurements is found to offer unique insight into both the structure of ionospheric irregularities and their impact on HF/VHF trans-ionospheric radio wave propagation.

  1. Ionomer Dynamics: Insights from Broadband Dielectric Spectroscopy

    Science.gov (United States)

    Runt, James

    2015-03-01

    Ionomers (polymers containing ionic functionality) have been traditionally used as packaging materials and in molding applications, and are now of increasing interest as candidate single ion conductors for energy storage devices, in energy conversion, and for other electroactive materials applications. The focus of this presentation is on the insight that broadband dielectric (impedance) spectroscopy brings to our understanding of ion and polymer dynamics of this family of materials. As an example of our recent work on relatively conductive ionomers, the first portion of the presentation will focus on anion conducting polyphosphazene ionomers, in which polymer bound cations are quaternized with either short alkyl or short ether oxygen chains. The low Tg, amorphous nature, and cation-solvating backbone distinguish polyphosphazenes as promising materials for ion conduction, the iodide variants being of particular interest in solar cells. In the second part of this overview, the first findings on the molecular dynamics of linear precise polyethylene-based ionomers containing 1-methylimidazolium bromide pendants on exactly every 9th, 15th, or 21st carbon atom will be summarized. In order to develop a robust interpretation of the dynamics of these materials, it is imperative to develop a thorough understanding of microphase separation (e.g. ion aggregation), and each of the above studies is complimented by multiangle X-ray scattering experiments. Supported by the NSF Polymers Program and DOE Basic Energy Sciences.

  2. Broadband unidirectional invisibility for airborne sound

    Science.gov (United States)

    Kan, Weiwei; Guo, Mengping; Shen, Zhonghua

    2018-05-01

    We present a metafluid-based broadband cloak capable of guiding acoustic waves around obstacles along given directions while maintaining the wavefront undisturbed. The required parameter distribution of the proposed cloak is derived by coordinate transformation and practically implemented by employing the acoustic metafluid formed with periodically arranged slabs in acoustic chambers. The method for independently modulating the effective mass density and bulk modulus of the metafluid is developed by tuning the geometry parameters and the temperature of the acoustic chamber in a specific process. By virtue of this free-modulated method, the range of realizable effective parameters is substantially broadened, and the acoustic impedance of the anisotropic structures can be well matched to the background. The performance of the designed structure is quantitatively evaluated in the frequency range of 3-4 kHz by the averaged invisibility factor. The results show that the proposed cloak is effective in manipulating the acoustic field along the given direction and suppressing the wave scattering from the hidden object.

  3. A Broadband Ultrathin Nonlinear Switching Metamaterial

    Directory of Open Access Journals (Sweden)

    E. Zarnousheh Farahani

    2017-05-01

    Full Text Available In this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient.

  4. Pricing by timing: innovating broadband data plans

    Science.gov (United States)

    Ha, Sangtae; Joe-Wong, Carlee; Sen, Soumya; Chiang, Mung

    2012-01-01

    Wireless Internet usage is doubling every year. Users are using more of high bandwidth data applications, and the heavy usage concentrates on several peak hours in a day, forcing ISPs to overprovision their networks accordingly. In order to remain profitable, ISPs have been using pricing as a congestion management tool. We review many of such pricing schemes in practice today and argue that they do not solve ISPs' problem of growing data traffic. We believe that dynamic, time-dependent usage pricing, which charges users based on when they access the Internet, can incentivize users to spread out their bandwidth consumption more evenly across different times of the day, thus helping ISPs to overcome the problem of peak congestion. Congestion pricing is not a new idea in itself, but the time for its implementation in data networks has finally arrived. Our key contribution lies in developing new analysis and a fully integrated system architecture, called TUBE (Time-dependent Usage-based Broadband price Engineering) that enables ISPs to implement the proposed TDP plan. The theory, simulation, and system implementation of TUBE system is further complemented with consumer surveys conducted in India and the US, along with preparations for a field trial that is currently underway.

  5. First Observation of the Submillimeter Polarization Spectrum in a Translucent Molecular Cloud

    Science.gov (United States)

    Ashton, Peter C.; Ade, Peter A. R.; Angilè, Francesco E.; Benton, Steven J.; Devlin, Mark J.; Dober, Bradley; Fissel, Laura M.; Fukui, Yasuo; Galitzki, Nicholas; Gandilo, Natalie N.; Klein, Jeffrey; Korotkov, Andrei L.; Li, Zhi-Yun; Martin, Peter G.; Matthews, Tristan G.; Moncelsi, Lorenzo; Nakamura, Fumitaka; Netterfield, Calvin B.; Novak, Giles; Pascale, Enzo; Poidevin, Frédérick; Santos, Fabio P.; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A.; Soler, Juan D.; Thomas, Nicholas E.; Tucker, Carole E.; Tucker, Gregory S.; Ward-Thompson, Derek

    2018-04-01

    Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM, but a troublesome contaminant for studies of cosmic microwave background polarization. In each case, an understanding of the significance of the polarization signal requires well-calibrated physical models of dust grains. Despite decades of progress in theory and observation, polarized dust models remain largely underconstrained. During its 2012 flight, the balloon-borne telescope BLASTPol obtained simultaneous broadband polarimetric maps of a translucent molecular cloud at 250, 350, and 500 μm. Combining these data with polarimetry from the Planck 850 μm band, we have produced a submillimeter polarization spectrum, the first for a cloud of this type. We find the polarization degree to be largely constant across the four bands. This result introduces a new observable with the potential to place strong empirical constraints on ISM dust polarization models in a previously inaccessible density regime. Compared to models by Draine & Fraisse, our result disfavors two of their models for which all polarization arises due only to aligned silicate grains. By creating simple models for polarized emission in a translucent cloud, we verify that extinction within the cloud should have only a small effect on the polarization spectrum shape, compared to the diffuse ISM. Thus, we expect the measured polarization spectrum to be a valid check on diffuse ISM dust models. The general flatness of the observed polarization spectrum suggests a challenge to models where temperature and alignment degree are strongly correlated across major dust components.

  6. Polarized targets and beams

    International Nuclear Information System (INIS)

    Meyer, W.

    1985-01-01

    First the experimental situation of the single-pion photoproduction and the photodisintegration of the deuteron is briefly discussed. Then a description of the Bonn polarization facilities is given. The point of main effort is put on the polarized target which plays a vital role in the program. A facility for photon induced double polarization experiments at ELSA will be presented in section 4. Properties of a tensor polarized deuteron target are discussed in section 5. The development in the field of polarized targets, especially on new target materials, enables a new generation of polarized target experiments with (polarized) electrons. Some comments on the use of a polarized target in combination with electron beams will be discussed in section 6. Electron deuteron scattering from a tensor polarized deuteron target is considered and compared with other experimental possibilities. (orig./HSI)

  7. Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light

    Science.gov (United States)

    Zhang, Lei; Hao, Jiaming; Ye, Huapeng; Yeo, Swee Ping; Qiu, Min; Zouhdi, Said; Qiu, Cheng-Wei

    2013-03-01

    We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by

  8. Characteristics of Broadband Seismic Noise in Taiwan and Neighboring Islands

    Science.gov (United States)

    Chen, Ching-Wei; Rau, Ruey-Juin

    2017-04-01

    We used seismic waveform data from 115 broad-band stations of BATS (Institute of Earth Science, Academia Sinica) and Central Weather Bureau Seismic Network from 2012 to 2016 for noise-level mapping in Taiwan and neighboring islands. We computed Power Spectral Density (PSD) for each station and analyzed long-term variance of microseism energy and polarizations of noise for severe weather events. The island of Taiwan is surrounded by ocean and the Central Range which has the highest peak Jade Mountain at 3,952 meters height occupies more than 66% of the island and departs it into the east and west coasts. The geographic settings then result in the high population density in the western plain and northern Taiwan. The dominant noise source in the microseism band (periods from 4-20 seconds) is the coupling between the near-coast ocean and sea floor which produces the high noise of averaging -130 dB along the west coastal area. In the eastern volcanic-arc coastal areas, the noise level is about 7% smaller than the west coast due to its deeper offshore water depth. As for the shorter periods (0.1-0.25 seconds) band, the so-called culture noise, an anthropic activity variance with the highest -103 dB can be identified in the metropolitan areas, such as the Taipei city and the noise level in the Central Range area is averaging -138 dB. Moreover, the noise also shows a daily and temporal evolution mainly related to the traffic effect. Furthermore, we determined the noise level for the entire island of Taiwan during 26-28 September, 2016, when the typhoon Megi hit the island and retrieved the enhancement of secondary microseism energy for each stations. Typhoon Megi landed in eastern and central Taiwan and reached the maximum wind speed of 45m/s in the surrounded eyewall. The Central Range, as a barrier, decreased the wind speed in southern Taiwan making an enhancement less than 10 dB, while in northern Taiwan where the direction the typhoon headed to, can reach more than 35

  9. Developing Advanced Broadband Microwave Detectors for Next-Generation CMB Polarization Studies

    Data.gov (United States)

    National Aeronautics and Space Administration — The photons of the cosmic microwave background (CMB) stream toward us from the boundary of the observable universe and arrive with information about both their point...

  10. Computing broadband accelerograms using kinematic rupture modeling

    International Nuclear Information System (INIS)

    Ruiz Paredes, J.A.

    2007-05-01

    In order to make the broadband kinematic rupture modeling more realistic with respect to dynamic modeling, physical constraints are added to the rupture parameters. To improve the slip velocity function (SVF) modeling, an evolution of the k -2 source model is proposed, which consists to decompose the slip as a sum of sub-events by band of k. This model yields to SVF close to the solution proposed by Kostrov for a crack, while preserving the spectral characteristics of the radiated wave field, i.e. a w 2 model with spectral amplitudes at high frequency scaled to the coefficient of directivity C d . To better control the directivity effects, a composite source description is combined with a scaling law defining the extent of the nucleation area for each sub-event. The resulting model allows to reduce the apparent coefficient of directivity to a fraction of C d , as well as to reproduce the standard deviation of the new empirical attenuation relationships proposed for Japan. To make source models more realistic, a variable rupture velocity in agreement with the physics of the rupture must be considered. The followed approach that is based on an analytical relation between the fracture energy, the slip and the rupture velocity, leads to higher values of the peak ground acceleration in the vicinity of the fault. Finally, to better account for the interaction of the wave field with the geological medium, a semi-empirical methodology is developed combining a composite source model with empirical Green functions, and is applied to the Yamaguchi, M w 5.9 earthquake. The modeled synthetics reproduce satisfactorily well the observed main characteristics of ground motions. (author)

  11. BROADBAND OBSERVATIONS OF HIGH REDSHIFT BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Paliya, Vaidehi S. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Parker, M. L.; Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Stalin, C. S., E-mail: vpaliya@g.clemson.edu [Indian Institute of Astrophysics, Block II, Koramangala, Bangalore-560034 (India)

    2016-07-01

    We present a multi-wavelength study of four high redshift blazars, S5 0014+81 ( z = 3.37), CGRaBS J0225+1846 ( z = 2.69), BZQ J1430+4205 ( z = 4.72), and 3FGL J1656.2−3303 ( z = 2.40) using quasi-simultaneous data from the Swift , Nuclear Spectroscopic Telescope Array ( NuSTAR ) and the Fermi -Large Area Telescope (LAT) and also archival XMM-Newton observations. Other than 3FGL J1656.2−3303, none of the sources were known as γ -ray emitters, and our analysis of ∼7.5 yr of LAT data reveals the first time detection of statistically significant γ -ray emission from CGRaBS J0225+1846. We generate the broadband spectral energy distributions (SED) of all the objects, centering at the epoch of NuSTAR observations and reproduce them using a one-zone leptonic emission model. The optical−UV emission in all the objects can be explained by radiation from the accretion disk, whereas the X-ray to γ -ray windows of the SEDs are found to be dominated by inverse Compton scattering off the broad line region photons. All of them host black holes that are billions of solar masses. Comparing the accretion disk luminosity and the jet power of these sources with a large sample of blazars, we find them to occupy a high disk luminosity–jet power regime. We also investigate the X-ray spectral properties of the sources in detail with a major focus on studying the causes of soft X-ray deficit, a feature generally seen in high redshift radio-loud quasars. We summarize that this feature could be explained based on the intrinsic curvature in the jet emission rather than being due to the external effects predicted in earlier studies, such as host galaxy and/or warm absorption.

  12. Broadband Spectral Investigations of Magnetar Bursts

    Science.gov (United States)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin

    2017-09-01

    We present our broadband (2-250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550-5418, SGR 1900+14, and SGR 1806-20 detected with the Rossi X-ray Timing Explorer (RXTE) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  13. Broadband Spectral Investigations of Magnetar Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Kırmızıbayrak, Demet; Şaşmaz Muş, Sinem; Kaneko, Yuki; Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu [Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı Tuzla, Istanbul 34956 (Turkey)

    2017-09-01

    We present our broadband (2–250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550−5418, SGR 1900+14, and SGR 1806−20 detected with the Rossi X-ray Timing Explorer ( RXTE ) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.

  14. Specdata: Automated Analysis Software for Broadband Spectra

    Science.gov (United States)

    Oliveira, Jasmine N.; Martin-Drumel, Marie-Aline; McCarthy, Michael C.

    2017-06-01

    With the advancement of chirped-pulse techniques, broadband rotational spectra with a few tens to several hundred GHz of spectral coverage are now routinely recorded. When studying multi-component mixtures that might result, for example, with the use of an electrical discharge, lines of new chemical species are often obscured by those of known compounds, and analysis can be laborious. To address this issue, we have developed SPECdata, an open source, interactive tool which is designed to simplify and greatly accelerate the spectral analysis and discovery. Our software tool combines both automated and manual components that free the user from computation, while giving him/her considerable flexibility to assign, manipulate, interpret and export their analysis. The automated - and key - component of the new software is a database query system that rapidly assigns transitions of known species in an experimental spectrum. For each experiment, the software identifies spectral features, and subsequently assigns them to known molecules within an in-house database (Pickett .cat files, list of frequencies...), or those catalogued in Splatalogue (using automatic on-line queries). With suggested assignments, the control is then handed over to the user who can choose to accept, decline or add additional species. Data visualization, statistical information, and interactive widgets assist the user in making decisions about their data. SPECdata has several other useful features intended to improve the user experience. Exporting a full report of the analysis, or a peak file in which assigned lines are removed are among several options. A user may also save their progress to continue at another time. Additional features of SPECdata help the user to maintain and expand their database for future use. A user-friendly interface allows one to search, upload, edit or update catalog or experiment entries.

  15. A Design Of Feeding Network For A Dual-Linear Polarization, Stacked, Probe-Fed Microstrip Patch Antenna Array

    DEFF Research Database (Denmark)

    Jaworski, G.; Krozer, Viktor

    2004-01-01

    Components of multilayer feed network are presented for application in broad-band dual-linear polarized stacked C-band antenna. Measurement results of wide band matching circuits and different types of power divider networks constituting parts of BFN demonstrate wideband operation. Suitable...

  16. Generation of 1.024-Tb/s Nyquist-WDM phase-conjugated twin vector waves by a polarization-insensitive optical parametric amplifier for fiber-nonlinearity-tolerant transmission

    DEFF Research Database (Denmark)

    Liu, Xiang; Hu, Hao; Chandrasekhar, S.

    2014-01-01

    We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all...

  17. Scattering with polarized neutrons

    International Nuclear Information System (INIS)

    Schweizer, J.

    2007-01-01

    In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

  18. Polarized Light Corridor Demonstrations.

    Science.gov (United States)

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  19. Techniques in polarization physics

    International Nuclear Information System (INIS)

    Clausnitzer, G.

    1974-01-01

    A review of the current status of the technical tools necessary to perform different kinds of polarization experiments is presented, and the absolute and relative accuracy with which data can be obtained is discussed. A description of polarized targets and sources of polarized fast neutrons is included. Applications of polarization techniques to other fields is mentioned briefly. (14 figures, 3 tables, 110 references) (U.S.)

  20. Polarized Moessbauer transitions

    International Nuclear Information System (INIS)

    Barb, D.

    1975-01-01

    Theoretical aspects of the emission, absorption and scattering of polarized gamma rays are reviewed for a general case of combined magnetic and electric hyperfine interactions; various possibilities of obtaining polarized gamma sources are described and examples are given of the applications of Moessbauer spectroscopy with polarized gamma rays in solving problems of solid state physics. (A.K.)

  1. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  2. Calculation of polarization effects

    International Nuclear Information System (INIS)

    Chao, A.W.

    1983-09-01

    Basically there are two areas of accelerator applications that involve beam polarization. One is the acceleration of a polarized beam (most likely a proton beam) in a synchrotron. Another concerns polarized beams in an electron storage ring. In both areas, numerical techniques have been very useful

  3. The relationship investigation between factors affecting demand for broadband and the level of satisfaction among broadband customers in the South East Coast of Sabah, Malaysia

    Science.gov (United States)

    Hashim, S. H. A.; Hamid, F. A.; Kiram, J. J.; Sulaiman, J.

    2017-09-01

    This paper aims to investigate the relationship between factors that affecting the demand for broadband and the level of satisfaction. Previous researchers have found that the adoption of broadband is greatly influenced by many factors. Thus, in this study, a self-administered questionnaire was developed to obtain the factors affecting demand for broadband among broadband customers as well as their level of satisfaction. Pearson correlation, one-way analysis of variance (ANOVA) and t-test were used for statistical interpretation of the relationship. This study shows that there are better relationships between several factors over demand for broadband and satisfaction level.

  4. Study of the spectral characteristics of unidentified galactic EGRET sources. Are they pulsar-like?

    Science.gov (United States)

    Merck, M.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Fichtel, C. E.; Fierro, J. M.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mayer-Hasselwander, H. A.; Michelson, P. F.; von Montigny, C.; Muecke, A.; Mukherjee, R.; Nolan, P. L.; Pohl, M.; Schneid, E.; Sreekumar, P.; Thompson, D. J.; Willis, T. D.

    1996-12-01

    A spectral study of unidentified galactic EGRET sources was performed. The derived spectra are compared to the spectra of pulsars to test the hypothesis, that a significant fraction of these sources are Geminga like radio-quiet pulsars (Yadigaroglu & Romani 1995ApJ...449..211Y). Most of the sources show significantly different spectra than expected under this hypothesis. Of those with spectra consistent with typical pulsar spectra, four are positionally consistent with young spin-powered radio pulsars leaving only very few Geminga type candidates in the sample.

  5. Detailed Balance Limit of Efficiency of Broadband-Pumped Lasers.

    Science.gov (United States)

    Nechayev, Sergey; Rotschild, Carmel

    2017-09-13

    Broadband light sources are a wide class of pumping schemes for lasers including LEDs, sunlight and flash lamps. Recently, efficient coupling of broadband light to high-quality micro-cavities has been demonstrated for on-chip applications and low-threshold solar-pumped lasers via cascade energy transfer. However, the conversion of incoherent to coherent light comes with an inherent price of reduced efficiency, which has yet to be assessed. In this paper, we derive the detailed balance limit of efficiency of broadband-pumped lasers and discuss how it is affected by the need to maintain a threshold population inversion and thermodynamically dictated minimal Stokes' shift. We show that lasers' slope efficiency is analogous to the nominal efficiency of solar cells, limited by thermalisation losses and additional unavoidable Stokes' shift. The lasers' power efficiency is analogous to the detailed balance limit of efficiency of solar cells, affected by the cavity mirrors and impedance matching factor, respectively. As an example we analyze the specific case of solar-pumped sensitized Nd 3+ :YAG-like lasers and define the conditions to reach their thermodynamic limit of efficiency. Our work establishes an upper theoretical limit for the efficiency of broadband-pumped lasers. Our general, yet flexible model also provides a way to incorporate other optical and thermodynamic losses and, hence, to estimate the efficiency of non-ideal broadband-pumped lasers.

  6. Broadband set-top box using MAP-CA processor

    Science.gov (United States)

    Bush, John E.; Lee, Woobin; Basoglu, Chris

    2001-12-01

    Advances in broadband access are expected to exert a profound impact in our everyday life. It will be the key to the digital convergence of communication, computer and consumer equipment. A common thread that facilitates this convergence comprises digital media and Internet. To address this market, Equator Technologies, Inc., is developing the Dolphin broadband set-top box reference platform using its MAP-CA Broadband Signal ProcessorT chip. The Dolphin reference platform is a universal media platform for display and presentation of digital contents on end-user entertainment systems. The objective of the Dolphin reference platform is to provide a complete set-top box system based on the MAP-CA processor. It includes all the necessary hardware and software components for the emerging broadcast and the broadband digital media market based on IP protocols. Such reference design requires a broadband Internet access and high-performance digital signal processing. By using the MAP-CA processor, the Dolphin reference platform is completely programmable, allowing various codecs to be implemented in software, such as MPEG-2, MPEG-4, H.263 and proprietary codecs. The software implementation also enables field upgrades to keep pace with evolving technology and industry demands.

  7. Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

    International Nuclear Information System (INIS)

    Semenova, V A; Kulya, M S; Bespalov, V G

    2016-01-01

    The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm. (paper)

  8. Broadband low-frequency sound isolation by lightweight adaptive metamaterials

    Science.gov (United States)

    Liao, Yunhong; Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming

    2018-03-01

    Blocking broadband low-frequency airborne noises is highly desirable in lots of engineering applications, while it is extremely difficult to be realized with lightweight materials and/or structures. Recently, a new class of lightweight adaptive metamaterials with hybrid shunting circuits has been proposed, demonstrating super broadband structure-borne bandgaps. In this study, we aim at examining their potentials in broadband sound isolation by establishing an analytical model that rigorously combines the piezoelectric dynamic couplings between adaptive metamaterials and acoustics. Sound transmission loss of the adaptive metamaterial is investigated with respect to both the frequency and angular spectrum to demonstrate their sound-insulation effects. We find that efficient sound isolation can indeed be pursued in the broadband bi-spectrum for not only the case of the small resonator's periodicity where only one mode relevant to the mass-spring resonance exists, but also for the large-periodicity scenario, so that the total weight can be even lighter, in which the multiple plate-resonator coupling modes appear. In the latter case, the negative spring stiffness provided by the piezoelectric stack has been utilized to suppress the resonance-induced high acoustic transmission. Such kinds of adaptive metamaterials could open a new approach for broadband noise isolation with extremely lightweight structures.

  9. Tunable Broadband Nanocarbon Transparent Conductor by Electrochemical Intercalation.

    Science.gov (United States)

    Wan, Jiayu; Xu, Yue; Ozdemir, Burak; Xu, Lisha; Sushkov, Andrei B; Yang, Zhi; Yang, Bao; Drew, Dennis; Barone, Veronica; Hu, Liangbing

    2017-01-24

    Optical transparent and electrical conducting materials with broadband transmission are important for many applications in optoelectronic, telecommunications, and military devices. However, studies of broadband transparent conductors and their controlled modulation are scarce. In this study, we report that reversible transmittance modulation has been achieved with sandwiched nanocarbon thin films (containing carbon nanotubes (CNTs) and reduced graphene oxide (rGO)) via electrochemical alkali-ion intercalation/deintercalation. The transmittance modulation covers a broad range from the visible (450 nm) to the infrared (5 μm), which can be achieved only by rGO rather than pristine graphene films. The large broadband transmittance modulation is understood with DFT calculations, which suggest a decrease in interband transitions in the visible range as well as a reduced reflection in the IR range upon intercalation. We find that a larger interlayer distance in few-layer rGO results in a significant increase in transparency in the infrared region of the spectrum, in agreement with experimental results. Furthermore, a reduced plasma frequency in rGO compared to few-layer graphene is also important to understand the experimental results for broadband transparency in rGO. The broadband transmittance modulation of the CNT/rGO/CNT systems can potentially lead to electrochromic and thermal camouflage applications.

  10. System and method for detection of dispersed broadband signals

    Science.gov (United States)

    Qian, S.; Dunham, M.E.

    1999-06-08

    A system and method for detecting the presence of dispersed broadband signals in real time are disclosed. The present invention utilizes a bank of matched filters for detecting the received dispersed broadband signals. Each matched filter uses a respective robust time template that has been designed to approximate the dispersed broadband signals of interest, and each time template varies across a spectrum of possible dispersed broadband signal time templates. The received dispersed broadband signal x(t) is received by each of the matched filters, and if one or more matches occurs, then the received data is determined to have signal data of interest. This signal data can then be analyzed and/or transmitted to Earth for analysis, as desired. The system and method of the present invention will prove extremely useful in many fields, including satellite communications, plasma physics, and interstellar research. The varying time templates used in the bank of matched filters are determined as follows. The robust time domain template is assumed to take the form w(t)=A(t)cos[l brace]2[phi](t)[r brace]. Since the instantaneous frequency f(t) is known to be equal to the derivative of the phase [phi](t), the trajectory of a joint time-frequency representation of x(t) is used as an approximation of [phi][prime](t). 10 figs.

  11. Bio-inspired heterogeneous composites for broadband vibration mitigation.

    Science.gov (United States)

    Chen, Yanyu; Wang, Lifeng

    2015-12-08

    Structural biological materials have developed heterogeneous and hierarchical architectures that are responsible for the outstanding performance to provide protection against environmental threats including static and dynamic loading. Inspired by this observation, this research aims to develop new material and structural concepts for broadband vibration mitigation. The proposed composite materials possess a two-layered heterogeneous architecture where both layers consist of high-volume platelet-shape reinforcements and low-volume matrix, similar to the well-known "brick and mortar" microstructure of biological composites. Using finite element method, we numerically demonstrated that broadband wave attenuation zones can be achieved by tailoring the geometric features of the heterogeneous architecture. We reveal that the resulting broadband attenuation zones are gained by directly superimposing the attenuation zones in each constituent layer. This mechanism is further confirmed by the investigation into the phonon dispersion relation of each layer. Importantly, the broadband wave attenuation capability will be maintained when the mineral platelet orientation is locally manipulated, yet a contrast between the mineral platelet concentrations of the two constituent layers is essential. The findings of this work will provide new opportunities to design heterogeneous composites for broadband vibration mitigation and impact resistance under mechanically challenging environmental conditions.

  12. Acceleration of polarized particles

    International Nuclear Information System (INIS)

    Buon, J.

    1992-05-01

    The spin kinetics of polarized beams in circular accelerators is reviewed in the case of spin-1/2 particles (electrons and protons) with emphasis on the depolarization phenomena. The acceleration of polarized proton beams in synchrotrons is described together with the cures applied to reduce depolarization, including the use of 'Siberian Snakes'. The in-situ polarization of electrons in storage rings due to synchrotron radiation is studied as well as depolarization in presence of ring imperfections. The applications of electron polarization to accurately calibrate the rings in energy and to use polarized beams in colliding-beam experiments are reviewed. (author) 76 refs., 19 figs., 1 tab

  13. Manta A New BroadBand OBS

    Science.gov (United States)

    Hello, Y.; Yegikyan, M.; Charvis, P.; Philippe, O.

    2017-12-01

    Manta is a new BroadBand OBS developed at Geoazur and commercialized by Osean. The design is inspired by 3-years autonomy MUG-OBS a Multiparameter Ocean Bottom System which carry a lot of sort of sensor types. As Mug-OBS, Manta-OBS rated 6000m is designed to resist a trawling. All the components are non corrosive such polyethylene, titanium and buoyancy is ensured by syntactic foam. Equipped in standard version with a Trillium compact OBS Manta has an autonomy of 18 months, but can accept on its 4 input channels any kind of signal as low as from an hydrophone or larger from other type of a seismometer or accelerometer. Tri-axial geophones unit (2 Hz or 4.5 Hz ) can replace the seismometer and will expend the lifespan for the instrument. The seismometer is encapsulated in a central well established by four panels of the main structure to protect it from sea current convection and is decoupled from main chassis. An health bulletin is recoverable by acoustic any time to facilitate the installation and during a visit when instrument is deployed. Main parameters for acquisition can be changed by acoustics command from surface at any time. Once at the bottom, release for the main sensor installation is programmed on a timer but controlled by the tilt of the OBS. If the tilt is too important based on programmed limits, sensor will not released automatically, but this can be forced by acoustic command after returning the tilt informations to the boat operator. Manta is equipped with flash light and AIS system for easy location at recovery, and can also send it's position by Iridium satellite in case of an unexpected ascent such caused by a possible trawling if deployed in shallow water. Clock drift calculation is automatically made against GPS time signal once the OBS return at the surface. The recovery of the OBS is initiated by an acoustic command. These new features made Manta a very versatile instrument for monitoring earthquakes.

  14. Bandwidth broadening of a graphene-based circular polarization converter by phase compensation.

    Science.gov (United States)

    Gao, Xi; Yang, Wanli; Cao, Weiping; Chen, Ming; Jiang, Yannan; Yu, Xinhua; Li, Haiou

    2017-10-02

    We present a broadband tunable circular polarization converter composed of a single graphene sheet patterned with butterfly-shaped holes, a dielectric spacer, and a 7-layer graphene ground plane. It can convert a linearly polarized wave into a circularly polarized wave in reflection mode. The polarization converter can be dynamically tuned by varying the Fermi energy of the single graphene sheet. Furthermore, the 7-layer graphene acting as a ground plane can modulate the phase of its reflected wave by controlling the Femi energy, which provides constructive interference condition at the surface of the single graphene sheet in a broad bandwidth and therefore significantly broadens the tunable bandwidth of the proposed polarization converter.

  15. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.

    1981-01-01

    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  16. The Physics of Polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    2015-10-01

    The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

  17. Broadband unidirectional cloaks based on flat metasurface focusing lenses

    International Nuclear Information System (INIS)

    Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

    2015-01-01

    Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects. (paper)

  18. Broadband unidirectional cloaks based on flat metasurface focusing lenses

    Science.gov (United States)

    Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

    2015-08-01

    Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects.

  19. Broadband and Resonant Approaches to Axion Dark Matter Detection.

    Science.gov (United States)

    Kahn, Yonatan; Safdi, Benjamin R; Thaler, Jesse

    2016-09-30

    When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. We propose a new experiment to detect this axion effective current. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. We consider both resonant and broadband readout circuits and show that a broadband approach has advantages at small axion masses. We estimate the reach of this design, taking into account the irreducible sources of noise, and demonstrate potential sensitivity to axionlike dark matter with masses in the range of 10^{-14}-10^{-6}  eV. In particular, both the broadband and resonant strategies can probe the QCD axion with a GUT-scale decay constant.

  20. Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

    Science.gov (United States)

    Kostylev, M.; Stashkevich, A. A.; Adeyeye, A. O.; Shakespeare, C.; Kostylev, N.; Ross, N.; Kennewell, K.; Magaraggia, R.; Roussigné, Y.; Stamps, R. L.

    2010-11-01

    The broadband microstrip ferromagnetic resonance (FMR), cavity FMR, and Brillouin light scattering spectroscopy techniques have been applied for detection and characterization of a magnetic inhomogeneity in a film sample. In the case of a 100 nm thick permalloy film, an additional magnetically depleted top sublayer has been detected due to pinning effect it produces on the magnetization in the bulk of the film. The pinning results in appearance of an exchange standing spin wave mode in the broadband FMR absorption spectrum, whose amplitudes are different depending on whether the film or the film substrate faces the microstrip transducer. Comparison of the experimental amplitudes for this mode with results of our theory for both film placements revealed that the depleted layer is located at the film surface facing away from the film substrate. Subsequent broadband FMR characterization of a large number of other presumably single-layer films with thicknesses in the range 30-100 nm showed the same result.

  1. National Broadband strategies – The case of Brazil

    DEFF Research Database (Denmark)

    Falch, Morten; Iaskio, Emerson

    2018-01-01

    as differences in institutional factors. For instance has the government played a leading role in Japan and South Korea, while US and UK have a strong emphasis on market forces and competition. Brazil has chosen their own strategy for broadband development. This strategy is defined within a specific national...... of comparing broadband strategies in different countries. The paper first describes these dimensions, and how the framework relates to other kinds of categorisations. Second it provides a brief overview of how the Brazilian telecom market developed. The subsequent section presents various policy initiatives......). Broadband for all is a widely accepted policy objective in both developed and developing countries. However, the policy strategies for achieving this goal are very different in different countries. These differences are originated in different levels of economic and technological development, as well...

  2. Broadband electromagnetic dipole scattering by coupled multiple nanospheres

    Science.gov (United States)

    Jing, Xufeng; Ye, Qiufeng; Hong, Zhi; Zhu, Dongshuo; Shi, Guohua

    2017-11-01

    With the development of nanotechnology, the ability to manipulate light at the nanoscale is critical to future optical functional devices. The use of high refractive index dielectric single silicon nanoparticle can achieve electromagnetic dipole resonant properties. Compared with single nanosphere, the use of dimer and trimer introduces an additional dimension (gap size) for improving the performance of dielectric optical devices through the coupling between closely connected silicon nanospheres. When changing the gap size between the nanospheres, the interaction between the particles can be from weak to strong. Compared with single nanospheres, dimerized or trimeric nanospheres exhibit more pronounced broadband scattering properties. In addition, by introducing more complex interaction, the trimericed silicon nanospheres exhibit a more significant increase in bandwidth than expected. In addition, the presence of the substrate will also contribute to the increase in the bandwidth of the nanospheres. The broadband response in dielectric nanostructures can be effectively applied to broadband applications such as dielectric nanoantennas or solar cells.

  3. Broadband enhancement of infrared absorption in microbolometers using Ag nanocrystals

    International Nuclear Information System (INIS)

    Hyun, Jerome K.; Ahn, Chi Won; Kim, Woo Choong; Kim, Tae Hyun; Hyun, Moon Seop; Kim, Hee Yeoun; Park, Jae Hong; Lee, Won-Oh

    2015-01-01

    High performance microbolometers are widely sought for thermal imaging applications. In order to increase the performance limits of microbolometers, the responsivity of the device to broadband infrared (IR) radiation needs to be improved. In this work, we report a simple, quick, and cost-effective approach to modestly enhance the broadband IR response of the device by evaporating Ag nanocrystals onto the light entrance surface of the device. When irradiated with IR light, strong fields are built up within the gaps between adjacent Ag nanocrystals. These fields resistively generate heat in the nanocrystals and underlying substrate, which is transduced into an electrical signal via a resistive sensing element in the device. Through this method, we are able to enhance the IR absorption over a broadband spectrum and improve the responsivity of the device by ∼11%

  4. 77 FR 62461 - Implementing Public Safety Broadband Provisions of the Middle Class Tax Relief and Job Creation...

    Science.gov (United States)

    2012-10-15

    ... Wireless Broadband Network,'' ``Special Purpose Bankruptcy Remote Entity,'' ``Upper 700 MHz D Block license... definitions ``700 MHz Public/Private Partnership,'' ``Network Assets Holder,'' ``Network Sharing Agreement...,'' ``Public safety broadband network operator,'' ``Shared Wireless Broadband Network, '' ``Special Purpose...

  5. Broadband dielectric spectroscopy of oxidized porous silicon

    International Nuclear Information System (INIS)

    Axelrod, Ekaterina; Urbach, Benayahu; Sa'ar, Amir; Feldman, Yuri

    2006-01-01

    Dielectric measurements accompanied by infrared absorption and photoluminescence (PL) spectroscopy were used to investigate the electrical and optical properties of oxidized porous silicon (PS). As opposed to non-oxidized PS, only high temperature relaxation processes could be resolved for oxidized PS. Two relaxation processes have been observed. The first process is related to dc-conductivity that dominates at high temperatures and low frequencies. After subtraction of dc-conductivity we could analyse a second high-temperature relaxation process that is related to interface polarization induced by charge carriers trapped at the host matrix-pore interfaces. We found that, while the main effect of the oxidation on the PL appears to be a size reduction in the silicon nanocrystals that gives rise to a blue shift of the PL spectrum, its main contribution to the dielectric properties turns out to be blocking of transport channels in the host tissue and activation of hopping conductivity between silicon nanocrystals

  6. Broadband dielectric spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Axelrod, Ekaterina [Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Urbach, Benayahu [Racah Institute of Physics and the Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Sa' ar, Amir [Racah Institute of Physics and the Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Feldman, Yuri [Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel)

    2006-04-07

    Dielectric measurements accompanied by infrared absorption and photoluminescence (PL) spectroscopy were used to investigate the electrical and optical properties of oxidized porous silicon (PS). As opposed to non-oxidized PS, only high temperature relaxation processes could be resolved for oxidized PS. Two relaxation processes have been observed. The first process is related to dc-conductivity that dominates at high temperatures and low frequencies. After subtraction of dc-conductivity we could analyse a second high-temperature relaxation process that is related to interface polarization induced by charge carriers trapped at the host matrix-pore interfaces. We found that, while the main effect of the oxidation on the PL appears to be a size reduction in the silicon nanocrystals that gives rise to a blue shift of the PL spectrum, its main contribution to the dielectric properties turns out to be blocking of transport channels in the host tissue and activation of hopping conductivity between silicon nanocrystals.

  7. Comparison of VP broadband tiltmeter and VS vertical pendulum tiltmeter

    Directory of Open Access Journals (Sweden)

    Wugang Ma

    2015-05-01

    Full Text Available Vertical pendulum (VP tiltmeter is a kind of earthquake precursor observation equipment, which is used to record the interaction force associated with astronomical tidal tilts caused. Currently, VP broadband tiltmeter and vertical sensor (VS vertical pendulum tiltmeter are primarily used. In this paper, we compare the two different instruments by using four aspects—mechanical structure, circuitry, zeroing, and bandwidth—based on their working principles and applications. We conclude that VP broadband tiltmeter is more superior compared with VS vertical pendulum tiltmeter because of its higher bandwidth and degree of automation.

  8. Broadband electrical impedance matching for piezoelectric ultrasound transducers.

    Science.gov (United States)

    Huang, Haiying; Paramo, Daniel

    2011-12-01

    This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.

  9. Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.

    Science.gov (United States)

    Lee, Joong Seok; Yoo, Sungmin; Ahn, Young Kwan; Kim, Yoon Young

    2015-09-01

    This paper investigates the feasibility of broadband sound blocking with rotationally symmetric extensible inclusions introduced in phononic crystals. By varying the size of four equally shaped inclusions gradually, the phononic crystal experiences remarkable changes in its band-stop properties, such as shifting/widening of multiple Bragg bandgaps and evolution to resonance gaps. Necessary extensions of the inclusions to block sound effectively can be determined for given incident frequencies by evaluating power transmission characteristics. By arraying finite dissimilar unit cells, the resulting phononic crystal exhibits broadband sound blocking from combinational effects of multiple Bragg scattering and local resonances even with small-numbered cells.

  10. Measurement uncertainty in broadband radiofrequency radiation level measurements

    Directory of Open Access Journals (Sweden)

    Vulević Branislav D.

    2014-01-01

    Full Text Available For the evaluation of measurement uncertainty in the measurement of broadband radio frequency radiation, in this paper we propose a new approach based on the experience of the authors of the paper with measurements of radiofrequency electric field levels conducted in residential areas of Belgrade and over 35 municipalities in Serbia. The main objective of the paper is to present practical solutions in the evaluation of broadband measurement uncertainty for the in-situ RF radiation levels. [Projekat Ministarstva nauke Republike Srbije, br. III43009

  11. Broadband polymer microstructured THz fiber coupler with downdoped cores

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Bang, Ole

    2010-01-01

    We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz.......We demonstrate a broadband THz directional coupler based on a dual core photonic crystal fiber (PCF) design with mechanically down-doped core regions. For a center frequency of 1.3 THz we demonstrate a bandwidth of 0.65 THz....

  12. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  13. Analysis of broadband aerodynamic noise from VS45

    Energy Technology Data Exchange (ETDEWEB)

    Dundabin, P. [Renewable Energy Systems Ltd., Glasgow, Scotland (United Kingdom)

    1997-12-31

    This paper describes the analysis of acoustic data taken from the VS45 at Kaiser-Wilhelm-Koog. The aim was to investigate the dependence of aerodynamic noise on tip speed and angle of attack. In particular, the dependence of noise in individual third octave bands on these variable is examined. The analysis is divided into 3 sections: data selection, data checks and analysis of broadband nacelle noise; analysis of broadband aerodynamic noise and its sensitivity to tip speed and angle of attack. (LN)

  14. Implementation of Scientific Computing Applications on the Cell Broadband Engine

    Directory of Open Access Journals (Sweden)

    Guochun Shi

    2009-01-01

    Full Text Available The Cell Broadband Engine architecture is a revolutionary processor architecture well suited for many scientific codes. This paper reports on an effort to implement several traditional high-performance scientific computing applications on the Cell Broadband Engine processor, including molecular dynamics, quantum chromodynamics and quantum chemistry codes. The paper discusses data and code restructuring strategies necessary to adapt the applications to the intrinsic properties of the Cell processor and demonstrates performance improvements achieved on the Cell architecture. It concludes with the lessons learned and provides practical recommendations on optimization techniques that are believed to be most appropriate.

  15. Workshop on polarized neutron filters and polarized pulsed neutron experiments

    International Nuclear Information System (INIS)

    Itoh, Shinichi

    2004-07-01

    The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

  16. Instrumentation with polarized neutrons

    International Nuclear Information System (INIS)

    Boeni, P.; Muenzer, W.; Ostermann, A.

    2009-01-01

    Neutron scattering with polarization analysis is an indispensable tool for the investigation of novel materials exhibiting electronic, magnetic, and orbital degrees of freedom. In addition, polarized neutrons are necessary for neutron spin precession techniques that path the way to obtain extremely high resolution in space and time. Last but not least, polarized neutrons are being used for fundamental studies as well as very recently for neutron imaging. Many years ago, neutron beam lines were simply adapted for polarized beam applications by adding polarizing elements leading usually to unacceptable losses in neutron intensity. Recently, an increasing number of beam lines are designed such that an optimum use of polarized neutrons is facilitated. In addition, marked progress has been obtained in the technology of 3 He polarizers and the reflectivity of large-m supermirrors. Therefore, if properly designed, only factors of approximately 2-3 in neutron intensity are lost. It is shown that S-benders provide neutron beams with an almost wavelength independent polarization. Using twin cavities, polarized beams with a homogeneous phase space and P>0.99 can be produced without significantly sacrificing intensity. It is argued that elliptic guides, which are coated with large m polarizing supermirrors, provide the highest flux.

  17. VT Fiber Optic Broadband Availability by Census Block - 12-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201012 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2010. This...

  18. VT Fiber Optic Broadband Availability by Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  19. Broadband Wireline Provider Service: Cable Modem - DOCSIS 3.0; BBRI_cableDOCSIS12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - DOCSIS 3.0" technology. Broadband availability is...

  20. VT Fiber Optic Broadband Availability by Census Block - 12-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201112 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2011. This...

  1. Broadband Wireline Provider Service: Symmetric xDSL; BBRI_DSLsym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Symmetric xDSL technology. Broadband availability is summarized at...

  2. VT Fiber Optic Broadband Availability by Census Block - 12-2012

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201212 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 12/31/2012. This...

  3. Broadband Wireline Provider Service: Cable Modem - Other; BBRI_cableOther12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - Other" technology. Broadband availability is...

  4. Broadband Wireline Provider Service: Asymmetric xDSL; BBRI_DSLasym12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via Asymmetric xDSL technology. Broadband availability is summarized...

  5. VT Fiber Optic Broadband Availability by Census Block - 06-2011

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201106 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2011. This...

  6. VT Fiber Optic Broadband Availability by Census Block - 06-2010

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201006 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2010. This...

  7. VT Current and Future Status of Broadband Availability by Sub-Census Block - 06-2013

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The VTBB201306 VT Broadband Availability Dataset represents wireline and wireless 'broadband service' availability in VT as of 6/30/2013. This...

  8. Broadband Wireline Provider Service: Optical Carrier - Fiber to the End User; BBRI_fiber12

    Data.gov (United States)

    University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Optical Carrier - Fiber to the End User" technology. Broadband...

  9. 77 FR 14340 - Proposed Information Collection; Comment Request; Broadband Technology Opportunities Program...

    Science.gov (United States)

    2012-03-09

    ..., broadband service by public safety agencies; and (5) To stimulate the demand for broadband, economic growth, and job creation. OMB also requires agencies administering grant programs to [[Page 14341

  10. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  11. Community Broadband Networks and the Opportunity for E-Government Services

    DEFF Research Database (Denmark)

    Williams, Idongesit

    2017-01-01

    Community Broadband Networks (CBN) facilitate Broadband connectivity in underserved areas in many countries. The lack of Broadband connectivity is one of the reasons for the slow diffusion of e-government services in many countries.This article explains how CBNs can be enabled by governments...... to facilitate the delivery of e–government services in underserved areas in the developed and developing countries.The Community Based Broadband Mobilization (CBNM) models are used as explanatory tools....

  12. Multiphoton polarization Bremsstrahlung effect

    International Nuclear Information System (INIS)

    Golovinskij, P.A.

    2001-01-01

    A general approach to induced polarization effects was formulated on the basis of theory of many particles in a strong periodic field. Correlation with the perturbation theory is shown and the types of effective polarization potentials both for isolated atoms and ions, and for ions in plasma, are provided. State of art in the theory of forced polarization Bremsstrahlung effect is analyzed and some outlooks for further experimental and theoretical studies are outlined [ru

  13. Interoperability of Services in an Open Broadband Market : Cases from the Netherlands

    NARCIS (Netherlands)

    Burgmeijer, J.

    2006-01-01

    End-to-end interoperability of broadband services and networks is a condition for an open broadband market. A business model for broadband service interoperability is given. Two cases from the Netherlands, of initiatives from the market to reach interoperability, are presented: E-norm and FIST VoIP.

  14. Reflecting metallic metasurfaces designed with stochastic optimization as waveplates for manipulating light polarization

    Science.gov (United States)

    Haberko, Jakub; Wasylczyk, Piotr

    2018-03-01

    We demonstrate that a stochastic optimization algorithm with a properly chosen, weighted fitness function, following a global variation of parameters upon each step can be used to effectively design reflective polarizing optical elements. Two sub-wavelength metallic metasurfaces, corresponding to broadband half- and quarter-waveplates are demonstrated with simple structure topology, a uniform metallic coating and with the design suited for the currently available microfabrication techniques, such as ion milling or 3D printing.

  15. Exploring the Connection between Parsec-scale Jet Activity and Broadband Outbursts in 3C 279

    Science.gov (United States)

    Rani, B.; Jorstad, S. G.; Marscher, A. P.; Agudo, I.; Sokolovsky, K. V.; Larionov, V. M.; Smith, P.; Mosunova, D. A.; Borman, G. A.; Grishina, T. S.; Kopatskaya, E. N.; Mokrushina, A. A.; Morozova, D. A.; Savchenko, S. S.; Troitskaya, Yu. V.; Troitsky, I. S.; Thum, C.; Molina, S. N.; Casadio, C.

    2018-05-01

    We use a combination of high-resolution very long baseline interferometry (VLBI) radio and multiwavelength flux density and polarization observations to constrain the physics of the dissipation mechanism powering the broadband flares in 3C 279 during an episode of extreme flaring activity in 2013–2014. Six bright flares superimposed on a long-term outburst are detected at γ-ray energies. Four of the flares have optical and radio counterparts. The two modes of flaring activity (faster flares sitting on top of a long-term outburst) present at radio, optical, and γ-ray frequencies are missing in X-rays. X-ray counterparts are only observed for two flares. The first three flares are accompanied by ejection of a new VLBI component (NC2), suggesting the 43 GHz VLBI core as the site of energy dissipation. Another new component, NC3, is ejected after the last three flares, which suggests that the emission is produced upstream from the core (closer to the black hole). The study therefore indicates multiple sites of energy dissipation in the source. An anticorrelation is detected between the optical percentage polarization (PP) and optical/γ-ray flux variations, while the PP has a positive correlation with optical/γ-ray spectral indices. Given that the mean polarization is inversely proportional to the number of cells in the emission region, the PP versus optical/γ-ray anticorrelation could be due to more active cells during the outburst than at other times. In addition to the turbulent component, our analysis suggests the presence of a combined turbulent and ordered magnetic field, with the ordered component transverse to the jet axis.

  16. Airborne Laser Polarization Sensor

    Science.gov (United States)

    Kalshoven, James, Jr.; Dabney, Philip

    1991-01-01

    Instrument measures polarization characteristics of Earth at three wavelengths. Airborne Laser Polarization Sensor (ALPS) measures optical polarization characteristics of land surface. Designed to be flown at altitudes of approximately 300 m to minimize any polarizing or depolarizing effects of intervening atmosphere and to look along nadir to minimize any effects depending on look angle. Data from measurements used in conjunction with data from ground surveys and aircraft-mounted video recorders to refine mathematical models used in interpretation of higher-altitude polarimetric measurements of reflected sunlight.

  17. Polarization of Be stars

    International Nuclear Information System (INIS)

    Johns, M.W.

    1975-01-01

    Linear polarization of starlight may be produced by electron scattering in the extended atmospheres of early type stars. Techniques are investigated for the measurement and interpretation of this polarization. Polarimetric observations were made of twelve visual double star systems in which at least one member was a B type star as a means of separating the intrinsic stellar polarization from the polarization produced in the interstellar medium. Four of the double stars contained a Be star. Evidence for intrinsic polarization was found in five systems including two of the Be systems, one double star with a short period eclipsing binary, and two systems containing only normal early type stars for which emission lines have not been previously reported. The interpretation of these observations in terms of individual stellar polarizations and their wavelength dependence is discussed. The theoretical basis for the intrinsic polarization of early type stars is explored with a model for the disk-like extended atmospheres of Be stars. Details of a polarimeter for the measurement of the linear polarization of astronomical point sources are also presented with narrow band (Δ lambda = 100A) measurements of the polarization of γ Cas from lambda 4000 to lambda 5800

  18. Polarization at SLC

    International Nuclear Information System (INIS)

    Swartz, M.L.

    1988-07-01

    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs

  19. Distributed Shared Memory for the Cell Broadband Engine (DSMCBE)

    DEFF Research Database (Denmark)

    Larsen, Morten Nørgaard; Skovhede, Kenneth; Vinter, Brian

    2009-01-01

    in and out of non-coherent local storage blocks for each special processor element. In this paper we present a software library, namely the Distributed Shared Memory for the Cell Broadband Engine (DSMCBE). By using techniques known from distributed shared memory DSMCBE allows programmers to program the CELL...

  20. Will they fly? : PPPs and the ultrafast broadband initiative

    NARCIS (Netherlands)

    Sadowski, B.M.; Howell, B.

    2012-01-01

    The political perception of New Zealand's broadband market performance as ‘poor' has underpinned many significant changes to the telecommunications policy and regulatory environments since 2001. Most recently, this has been manifested in substantial government subsidies by way of public-private

  1. Impact of cyclostationarity on fan broadband noise prediction

    Science.gov (United States)

    Wohlbrandt, A.; Kissner, C.; Guérin, S.

    2018-04-01

    One of the dominant noise sources of modern Ultra High Bypass Ratio (UHBR) engines is the interaction of the rotor wakes with the leading edges of the stator vanes in the fan stage. While the tonal components of this noise generation mechanism are fairly well understood by now, the broadband components are not. This calls to further the understanding of the broadband noise generation in the fan stage. This article introduces a new extension to the Random Particle Mesh (RPM) method, which accommodates in-depth studies of the impact of cyclostationary wake characteristics on the broadband noise in the fan stage. The RPM method is used to synthesize a turbulence field in the stator domain using a URANS simulation characterized by time-periodic turbulence and mean flow. The rotor-stator interaction noise is predicted by a two-dimensional CAA computation of the stator cascade. The impact of cyclostationarity is decomposed into various effects, which are separately investigated. This leads to the finding that the periodic turbulent kinetic energy (TKE) and periodic flow have only a negligible effect on the radiated sound power. The impact of the periodic integral length scale (TLS) is, however, substantial. The limits of a stationary representation of the TLS are demonstrated making this new extension to the RPM method indispensable when background and wake TKE are of comparable level. Good agreement of the predictions with measurements obtained from the 2015 AIAA Fan Broadband Noise Prediction Workshop are also shown.

  2. Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

    KAUST Repository

    Yu, Zongfu; Raman, Aaswath; Fan, Shanhui

    2012-01-01

    to an upper bound dictated by the second law of thermodynamics. Such bound limits how efficient light can be coupled to any photonic structure. As one example of application, we use this upper bound to derive the limit of light absorption in broadband solar

  3. Biobased Nanoparticles for Broadband UV Protection with Photostabilized UV Filters

    NARCIS (Netherlands)

    Hayden, D.R.|info:eu-repo/dai/nl/412640694; Imhof, A.|info:eu-repo/dai/nl/145641600; Velikov, K. P.|info:eu-repo/dai/nl/239483472

    2016-01-01

    Sunscreens rely on multiple compounds to provide effective and safe protection against UV radiation. UV filters in sunscreens, in particular, provide broadband UV protection but are heavily linked to adverse health effects due to the generation of carcinogenic skin-damaging reactive oxygen species

  4. Novel crystalline-waveguide broadband light sources for interferometry

    NARCIS (Netherlands)

    Pollnau, Markus

    In recent years, broadband fiber interferometers have become very popular as basic instruments used in optical low-coherence reflectometry for diagnostics of fiber and integrated optics devices or in optical coherence tomography (OCT) for imaging applications in the biomedical field. The

  5. Mission-Critical Mobile Broadband Communications in Open Pit Mines

    DEFF Research Database (Denmark)

    Uzeda Garcia, Luis Guilherme; Portela Lopes de Almeida, Erika; Barbosa, Viviane S. B.

    2016-01-01

    that need to be met by the wireless network. This article introduces fundamental concepts behind open-pit mining and discusses why this ever changing environment coupled with strict industrial reliability requirements pose unique challenges to traditional broadband network planning and optimization...

  6. Control over multiscale mixing in broadband-forced turbulence

    NARCIS (Netherlands)

    Kuczaj, Arkadiusz K.; Geurts, Bernardus J.

    2008-01-01

    The effects of explicit flow modulation on the dispersion of a passive scalar field are studied. Broadband forcing is applied to homogeneous isotropic turbulence to modulate the energy cascading and alter the kinetic energy spectrum. Consequently, a manipulation of turbulent flow can be achieved

  7. Photonic crystal fiber design for broadband directional coupling

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Bang, Ole; Bjarklev, Anders Overgaard

    2004-01-01

    A novel design for a broadband directional coupler based on a photonic crystal fiber is investigated numerically. It is shown that suitable index-depressing doping of the core regions in an index-guiding twin-core photonic crystal fiber can stabilize the coupling coefficient between the cores over...

  8. Multicomponent gas analysis using broadband quantum cascade laser spectroscopy

    NARCIS (Netherlands)

    Reyes Reyes, A.; Hou, Z.; Van Mastrigt, E.; Horsten, R.C.; De Jongste, J.C.; Pijnenburg, M.W.; Urbach, H.P.; Bhattacharya, N.

    2014-01-01

    We present a broadband quantum cascade laser-based spectroscopic system covering the region between 850 and 1250 cm?1. Its robust multipass cavity ensures a constant interaction length over the entire spectral region. The device enables the detection and identification of numerous molecules present

  9. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Tian, Zhen; Gu, Jianqiang; Yue, Weisheng; Zhang, Shuang; Han, Jiaguang; Zhang, Weili; Zhang, Weili

    2015-01-01

    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  10. Catalyzing Broadband Internet in Africa | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project aims to inform policies that help marginalized groups in Africa, such as women and the poor, to take advantage of the social and economic opportunities of broadband Internet. Internet access is critical for social and economic development in developing countries. According to a 2009 World Bank study, a 10% ...

  11. 75 FR 36071 - Framework for Broadband Internet Service

    Science.gov (United States)

    2010-06-24

    ... Internet service. Introduction 3. This Commission exists ``[f]or the purpose of regulating interstate and... news groups, the ability to create a personal Web page, and the ability to retrieve information from... broadband policies. 31. Some have suggested that although the D.C. Circuit rejected the Commission's theory...

  12. Broadband phase difference method for ultrasonic velocimetry in molten glass

    International Nuclear Information System (INIS)

    Kikura, Hiroshige; Ihara, Tomonori

    2016-01-01

    This study aims to develop ultrasonic Doppler velocimetry in molten glass. Realization of such a technique has two difficulties: ultrasonic transmission into molten salt and Doppler signal processing. Buffer rod technique was developed in our research to transmit ultrasound into high temperature molten glass. This article discusses newly developed signal processing technique named broadband phase difference method. (J.P.N.)

  13. The social surplus of broadband initiatives in compulsory education

    Directory of Open Access Journals (Sweden)

    David Peter Parsons

    2016-10-01

    Full Text Available In 2010, the New Zealand government embarked upon an ambitious programme of broadband infrastructure investment, a process that will continue until at least 2019. Part of this investment is specifically targeted at compulsory education, with initiatives that include bringing fibre connections to the school gate, supporting on-site network upgrades (including wireless and providing teaching, learning and support services delivered through these networks. Such investments are not made without some projections of the likely rate of return, but calculating return on investment (ROI in educational broadband is complex, as it encompasses a range of factors. This article reports on an interview-based study engaging a range of stakeholders in educational broadband provision. The study utilises a research model that considers the various elements of social surplus, namely; producer surplus (savings, producer surplus (profit and consumer surplus (perceived value over and above cost, to explore the elements of social surplus that have been used to define educational broadband ROI calculations and justify the scale of investment. The results indicate that all three components of social surplus are relevant, though the concept of profit can only be seen in the broader context of long term contributions to the economy. A note of caution is that projections of ROI based only on positive returns fail to acknowledge the potential for some innovations to actually increase costs. Further, purely quantitative models do not properly take into account qualitative components of consumer surplus.

  14. Fast elliptic-curve cryptography on the Cell Broadband Engine

    NARCIS (Netherlands)

    Costigan, N.; Schwabe, P.; Preneel, B.

    2009-01-01

    This paper is the first to investigate the power of the Cell Broadband Engine for state-of-the-art public-key cryptography. We present a high-speed implementation of elliptic-curve Diffie-Hellman (ECDH) key exchange for this processor, which needs 697080 cycles on one Synergistic Processor Unit for

  15. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...

  16. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu

    2015-02-12

    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  17. Multiphase lattice Boltzmann on the Cell Broadband Engine

    International Nuclear Information System (INIS)

    Belletti, F.; Mantovani, F.; Tripiccione, R.; Biferale, L.; Schifano, S.F.; Toschi, F.

    2009-01-01

    Computational experiments are one of the most used and flexible investigation tools in fluid dynamics. The Lattice Boltzmann Equation is a well established computational method particularly promising for multi-phase flows at micro and macro scales. Here we present preliminary results on performances of the Lbe method on the Cell Broadband Engine platform.

  18. Broadband illusion optical devices based on conformal mappings

    Science.gov (United States)

    Xiong, Zhan; Xu, Lin; Xu, Ya-Dong; Chen, Huan-Yang

    2017-10-01

    In this paper, we propose a simple method of illusion optics based on conformal mappings. By carefully developing designs with specific conformal mappings, one can make an object look like another with a significantly different shape. In addition, the illusion optical devices can work in a broadband of frequencies.

  19. Energy savings in mobile broadband network based on load predictions

    DEFF Research Database (Denmark)

    Samulevicius, Saulius; Pedersen, Torben Bach; Sørensen, Troels Bundgaard

    2012-01-01

    Abstract—The deployment of new network equipment is resulting in increasing energy consumption in mobile broadband networks (MBNs). This contributes to higher CO2 emissions. Over the last 10 years MBNs have grown considerably, and are still growing to meet the evolution in traffic volume carried...

  20. Characterisation of optical filters for broadband UVA radiometer

    Science.gov (United States)

    Alves, Luciana C.; Coelho, Carla T.; Corrêa, Jaqueline S. P. M.; Menegotto, Thiago; Ferreira da Silva, Thiago; Aparecida de Souza, Muriel; Melo da Silva, Elisama; Simões de Lima, Maurício; Dornelles de Alvarenga, Ana Paula

    2016-07-01

    Optical filters were characterized in order to know its suitability for use in broadband UVA radiometer head for spectral irradiance measurements. The spectral transmittance, the angular dependence and the spatial uniformity of the spectral transmittance of the UVA optical filters were investigated. The temperature dependence of the transmittance was also studied.

  1. Imaging of Polarization-dependent Photocurrent in Graphene Photodevices

    Science.gov (United States)

    Kim, Minjung; Yoon, Duhee; Ang Yoon, Ho; Lee, Sang Wook; Cheong, Hyeonsik

    2012-02-01

    Recently, a metal-graphene-metal photodetector for high-speed optical communications was reported. In addition, a graphene-based photodetector was reported to be able to absorb broadband light owing to the unique band structure of graphene [Mueller et al., Nature Photonics 4, 297 (2010)]. We investigated the polarization dependence of the photocurrent generated in metal-graphene-metal junctions. The graphene photodevice was fabricated by depositing Pd/Au and Ti/Au electrodes on single-layer graphene samples. When the polarization of incident laser beam is rotated with respect to the metal-graphene-metal junction, the photocurrent is significantly modulated. In addition, we measured the exact positions where the photocurrent is generated by measuring the photocurrent and Raman images of the graphene photodevices simultaneously.

  2. The optical and near-infrared continuum polarization of five magnetic white dwarf stars - new observations and considerations regarding its origin

    Energy Technology Data Exchange (ETDEWEB)

    West, S.C. (Carnegie Institution of Washington, Observatories, Pasadena, CA (USA) Steward Observatory, Tucson, AZ (USA))

    1989-10-01

    Linear and circular broadband continuum polarization measurements throughout the 0.35-1.65-micron spectral region were obtained for GrW +70 deg 8247, GD 229, G240-72, G227-35, and LP 790-29. The continuum is found to be characterized by significant Coulomb modification of the Landau-type autoionization thresholds. The spectral characteristics of continuum polarization originating from a centered dipole field distribution are predicted. The magnetobremsstrahlung model can describe several characteristics of the polarization of Grw + 70 deg 8247, suggesting that plasma eigenmodes draw the resultant continuum polarization away from a photoionization edge. 86 refs.

  3. Unbundling in Current Broadband and Next-Generation Ultra-Broadband Access Networks

    Science.gov (United States)

    Gaudino, Roberto; Giuliano, Romeo; Mazzenga, Franco; Valcarenghi, Luca; Vatalaro, Francesco

    2014-05-01

    This article overviews the methods that are currently under investigation for implementing multi-operator open-access/shared-access techniques in next-generation access ultra-broadband architectures, starting from the traditional "unbundling-of-the-local-loop" techniques implemented in legacy twisted-pair digital subscriber line access networks. A straightforward replication of these copper-based unbundling-of-the-local-loop techniques is usually not feasible on next-generation access networks, including fiber-to-the-home point-to-multipoint passive optical networks. To investigate this issue, the article first gives a concise description of traditional copper-based unbundling-of-the-local-loop solutions, then focalizes on both next-generation access hybrid fiber-copper digital subscriber line fiber-to-the-cabinet scenarios and on fiber to the home by accounting for the mix of regulatory and technological reasons driving the next-generation access migration path, focusing mostly on the European situation.

  4. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  5. Observations on the variability of linear polarization in late-type dwarf stars

    Energy Technology Data Exchange (ETDEWEB)

    Huovelin, J.; Linnaluoto, S.; Tuominen, I.; Virtanen, H.

    1989-04-01

    Broadband (UBV) linear polarimetric observations of a sample of late-type (F7-K5) dwarfs are reported. The observations include ten stars and extend over a maximum of 20 nights. Seven stars show significant temporal variability of polarization, which could be interpreted as rotational modulation due to slowly varying magnetic regions. Magnetic intensification in saturated Zeeman sensitive absorption lines is suggested as the dominant effect connecting linear polarization with magnetic activity in the most active single late-type dwarfs, while the wavelength dependence in the less active stars could also be due to a combination of Rayleigh and Thomson scattering.

  6. Measurement of product rotational alignment in associative-ionization collisions between polarized Na(3p) atoms

    International Nuclear Information System (INIS)

    Wang, M.; de Vries, M.S.; Weiner, J.

    1986-01-01

    We have studied the effect of reactant Na(3p) polarization on the rotational angular momentum alignment of product Na 2 + ions arising from associative-ionization (AI) collisions. Our results show that sensitivity of the AI rate constant to initial atomic polarization persists even when all hyperfine states are populated with broadband (3 cm -1 ) pulsed laser excitation of Na( 2 P/sub 3/2/) and that the spatial distribution of product rotational angular momentum vectors is anisotropic. We discuss a qualitative description of the collision process consistent with our measurements which indicates that sigma-orbital symmetry is preferred to π-orbital symmetry as the colliding partners approach

  7. Modifications of Surface Wave Discrimination Filter Based on the Polarization Properties

    International Nuclear Information System (INIS)

    Kutlu, Y. A.; Sayil, N.

    2007-01-01

    The polarization properties of Love and Rayleigh waves are utilized to design Surface Wave Discrimination Filter. Filtering process for a selected window length and moving interval is that the amplitudes at each frequency on vertical, radial and transverse components are weighted according to how closely the theoretical three-dimensional particle motion pattern. In this study, weighted functions have been modified for epicenteral distances smaller than about 2200 km to corresponding with angular distribution of polarization parameters obtained from computed synthetic seismograms. Modified Surface Wave Discrimination Filter has been tested on synthetic seismograms and digital three-components broadband records at Trabzon earthquake station

  8. Chirality-induced polarization effects in the cuticle of scarab beetles: 100 years after Michelson

    Science.gov (United States)

    Arwin, Hans; Magnusson, Roger; Landin, Jan; Järrendahl, Kenneth

    2012-04-01

    One hundred years ago Michelson discovered circular polarization in reflection from beetles. Today a novel Mueller-matrix ellipsometry setup allows unprecedented detailed characterization of the beetles' polarization properties. A formalism based on elliptical polarization for description of reflection from scarab beetles is here proposed and examples are given on four beetles of different character: Coptomia laevis - a simple dielectric mirror; Cetonia aurata - a left-hand narrow-band elliptical polarizer; Anoplognathus aureus - a broad-band elliptical polarizer; and Chrysina argenteola - a left-hand polarizer for visible light at small angles, whereas for larger angles, red reflected light is right-handed polarized. We confirm the conclusion of previous studies which showed that a detailed quantification of ellipticity and degree of polarization of cuticle reflection can be performed instead of only determining whether reflections are circularly polarized or not. We additionally investigate reflection as a function of incidence angle. This provides much richer information for understanding the behaviour of beetles and for structural analysis.

  9. TRANSVERSELY POLARIZED Λ PRODUCTION

    International Nuclear Information System (INIS)

    BORER, D.

    2000-01-01

    Transversely polarized Λ production in hard scattering processes is discussed in terms of a leading twist T-odd fragmentation function which describes the fragmentation of an unpolarized quark into a transversely polarized Λ. We focus on the properties of this function and its relevance for the RHIC and HERMES experiments

  10. Our Polar Past

    Science.gov (United States)

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  11. Marine polar steroids

    International Nuclear Information System (INIS)

    Stonik, Valentin A

    2001-01-01

    Structures, taxonomic distribution and biological activities of polar steroids isolated from various marine organisms over the last 8-10 years are considered. The peculiarities of steroid biogenesis in the marine biota and their possible biological functions are discussed. Syntheses of some highly active marine polar steroids are described. The bibliography includes 254 references.

  12. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  13. Polarization Optics in Telecommunications

    CERN Document Server

    Damask, Jay N

    2005-01-01

    The strong investments into optical telecommunications in the late 1990s resulted in a wealth of new research, techniques, component designs, and understanding of polarization effects in fiber. Polarization Optics in Telecommunications brings together recent advances in the field to create a standard, practical reference for component designers and optical fiber communication engineers. Beginning with a sound foundation in electromagnetism, the author offers a dissertation of the spin-vector formalism of polarization and the interaction of light with media. Applications discussed include optical isolators, optical circulators, fiber collimators, and a variety of applied waveplate and prism combinations. Also included in an extended discussion of polarization-mode dispersion (PMD) and polarization-dependent loss (PDL), their representation, behavior, statistical properties, and measurement. This book draws extensively from the technical and patent literature and is an up-to-date reference for researchers and c...

  14. Parallel Polarization State Generation.

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-05-17

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  15. Astronomy in Denver: Probing Interstellar Circular Polarization with Polvis, a Full Stokes Single Shot Polarimeter

    Science.gov (United States)

    Wolfe, Tristan; Stencel, Robert E.

    2018-06-01

    Measurements of optical circular polarization (Stokes V) introduced by dust grains in the ISM are important for two main reasons. First of all, the polarization itself contains information about the metallic versus dielectric composition of the dust grains themselves (H. C. van de Hulst 1957, textbook). Additionally, circular polarization can help constrain the interstellar component of the polarization of any source that may have intrinsic polarization, which needs to be calibrated for astrophysical study. Though interstellar circular polarization has been observed (P. G. Martin 1972, MNRAS 159), most broadband measurements of ISM polarization include linear polarization only (Stokes Q and U), due to the relatively low circular polarization signal and the added instrumentation complexity of including V-measurement capability. Prior circular polarization measurements have also received very little follow-up in the past several decades, even as polarimeters have become more accurate due to advances in technology. The University of Denver is pursuing these studies with POLVIS, a prototype polarimeter that utilizes a stress-engineered optic ("SEO", A. K. Spilman and T. G. Brown 2007, Applied Optics IP 46) to produce polarization-dependent PSFs (A. M. Beckley and T. G. Brown 2010, Proc SPIE 7570). These PSFs are analyzed to provide simultaneous Stokes I, Q, U, and V measurements, in a single beam and single image, along the line-of-sight to point source-like objects. Polvis is the first polarimeter to apply these optics and measurement techniques for astronomical observations. We present the first results of this instrument in B, V, and R wavebands, providing a fresh look at full Stokes interstellar polarization. Importantly, this set of efforts will constrain the ISM contribution to the polarization with respect to intrinsic stellar components. The authors are grateful to the estate of William Herschel Womble for the support of astronomy at the University of Denver

  16. Polar bears at risk

    Energy Technology Data Exchange (ETDEWEB)

    Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

    2002-05-01

    Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such

  17. Polarized atomic beams for targets

    International Nuclear Information System (INIS)

    Grueebler, W.

    1984-01-01

    The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density

  18. GUIDE FOR POLARIZED NEUTRONS

    Science.gov (United States)

    Sailor, V.L.; Aichroth, R.W.

    1962-12-01

    The plane of polarization of a beam of polarized neutrons is changed by this invention, and the plane can be flipped back and forth quicitly in two directions in a trouble-free manner. The invention comprises a guide having a plurality of oppositely directed magnets forming a gap for the neutron beam and the gaps are spaced longitudinally in a spiral along the beam at small stepped angles. When it is desired to flip the plane of polarization the magnets are suitably rotated to change the direction of the spiral of the gaps. (AEC)

  19. Heidelberg polarized alkali source

    International Nuclear Information System (INIS)

    Kraemer, D.; Steffens, E.; Jaensch, H.; Philipps Universitaet, Marburg, Germany)

    1984-01-01

    A new atomic beam type polarized alkali ion source has been installed at Heidelberg. In order to improve the beam polarization considerably optical pumping is applied in combination with an adiabatic medium field transition which results in beams in single hyperfine sublevels. The m state population is determined by laser-induced fluorescence spectroscopy. Highly polarized beams (P/sub s/ > 0.9, s = z, zz) with intensities of 30 to 130 μA can be extracted for Li + and Na + , respectively

  20. Nonlinear Analysis of Renal Autoregulation Under Broadband Forcing Conditions

    DEFF Research Database (Denmark)

    Marmarelis, V Z; Chon, K H; Chen, Y M

    1994-01-01

    Linear analysis of renal blood flow fluctuations, induced experimentally in rats by broad-band (pseudorandom) arterial blood pressure forcing at various power levels, has been unable to explain fully the dynamics of renal autoregulation at low frequencies. This observation has suggested...... the possibility of nonlinear mechanisms subserving renal autoregulation at frequencies below 0.2 Hz. This paper presents results of 3rd-order Volterra-Wiener analysis that appear to explain adequately the nonlinearities in the pressure-flow relation below 0.2 Hz in rats. The contribution of the 3rd-order kernel...... in describing the dynamic pressure-flow relation is found to be important. Furthermore, the dependence of 1st-order kernel waveforms on the power level of broadband pressure forcing indicates the presence of nonlinear feedback (of sigmoid type) based on previously reported analysis of a class of nonlinear...

  1. Broadband infrared absorption enhancement by electroless-deposited silver nanoparticles

    DEFF Research Database (Denmark)

    Gritti, Claudia; Raza, Søren; Kadkhodazadeh, Shima

    2017-01-01

    Decorating semiconductor surfaces with plasmonic nanoparticles (NPs) is considered a viable solution for enhancing the absorptive properties of photovoltaic and photodetecting devices. We propose to deposit silver NPs on top of a semiconductor wafer by a cheap and fast electroless plating technique....... Optical characterization confirms that the random array of electroless-deposited NPs improves absorption by up to 20% in a broadband of nearinfrared frequencies from the bandgap edge to 2000 nm. Due to the small filling fraction of particles, the reflection in the visible range is practically unchanged......, which points to the possible applications of such deposition method for harvesting photons in nanophotonics and photovoltaics. The broadband absorption is a consequence of the resonant behavior of particles with different shapes and sizes, which strongly localize the incident light at the interface...

  2. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M; Labelle, André J; Thon, Susanna M; Lan, Xinzheng; Hoogland, Sjoerd; Sargent, Edward H

    2013-01-01

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  3. Broadband Laser Ranging for Position Measurements in Shock Physics Experiments

    Science.gov (United States)

    Rhodes, Michelle; Bennett, Corey; Daykin, Edward; Younk, Patrick; Lalone, Brandon; Kostinski, Natalie

    2017-06-01

    Broadband laser ranging (BLR) is a recently developed measurement system that provides an attractive option for determining the position of shock-driven surfaces. This system uses broadband, picosecond (or femtosecond) laser pulses and a fiber interferometer to measure relative travel time to a target and to a reference mirror. The difference in travel time produces a delay difference between pulse replicas that creates a spectral beat frequency. The spectral beating is recorded in real time using a dispersive Fourier transform and an oscilloscope. BLR systems have been designed that measure position at 12.5-40 MHz with better than 100 micron accuracy over ranges greater than 10 cm. We will give an overview of the basic operating principles of these systems. Prepared by LLNL under Contract DE-AC52-07NA27344, by LANL under Contract DE-AC52-06NA25396, and by NSTec Contract DE-AC52-06NA25946.

  4. Characteristics of hybrid broadcast broadband television (HbbTV

    Directory of Open Access Journals (Sweden)

    Jakšić Branimir

    2017-01-01

    Full Text Available This paper describes the working principle of hybrid broadcast-broadband TV (Hybrid Broadcast Broadband TV - HbbTV. The architecture of HbbTV system is given, the principle of its operation, as well as an overview of HbbTV specification standards that are in use, with their basic characteristics. Here are described the services provided by Hybrid TV. It is also provided an overview of the distribution of HbbTV services in Europe in terms of the number of TV channels that HbbTV services offer, the number of active hybrid TV devices, HbbTV standards which are in use and models of broadcast networks used to distribute HbbTV service.

  5. Radiative cooling and broadband phenomenon in low-frequency waves

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial -plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves. Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period, and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabatic heating. when the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.

  6. The broadband spectral energy distributions of SDSS blazars

    Science.gov (United States)

    Li, Huai-Zhen; Chen, Luo-En; Jiang, Yun-Guo; Yi, Ting-Feng

    2015-07-01

    We compiled the radio, optical and X-ray data of blazars from the Sloan Digital Sky Survey database, and presented the distribution of luminosities and broadband spectral indices. The distribution of luminosities shows that the averaged luminosity of flat spectrum radio quasars (FSRQs) is larger than that of BL Lacertae (BL Lac) objects. On the other hand, the broadband spectral energy distribution reveals that FSRQs and low energy peaked BL Lac objects have similar spectral properties, but high energy peaked BL Lac objects have a distinct spectral property. This may be due to the fact that different subclasses of blazars have different intrinsic environments and are at different cooling levels. Even so, a unified scheme is also revealed from the color-color diagram, which hints that there are similar physical processes operating in all objects under a range of intrinsic physical conditions or beaming parameters. Supported by the National Natural Science Foundation of China.

  7. Broadband and chiral binary dielectric meta-holograms.

    Science.gov (United States)

    Khorasaninejad, Mohammadreza; Ambrosio, Antonio; Kanhaiya, Pritpal; Capasso, Federico

    2016-05-01

    Subwavelength structured surfaces, known as meta-surfaces, hold promise for future compact and optically thin devices with versatile functionalities. By revisiting the concept of detour phase, we demonstrate high-efficiency holograms with broadband and chiral imaging functionalities. In our devices, the apertures of binary holograms are replaced by subwavelength structured microgratings. We achieve broadband operation from the visible to the near infrared and efficiency as high as 75% in the 1.0 to 1.4 μm range by compensating for the inherent dispersion of the detour phase with that of the subwavelength structure. In addition, we demonstrate chiral holograms that project different images depending on the handedness of the reference beam by incorporating a geometric phase. Our devices' compactness, lightness, and ability to produce images even at large angles have significant potential for important emerging applications such as wearable optics.

  8. Broadband solar absorption enhancement via periodic nanostructuring of electrodes.

    KAUST Repository

    Adachi, Michael M

    2013-10-14

    Solution processed colloidal quantum dot (CQD) solar cells have great potential for large area low-cost photovoltaics. However, light utilization remains low mainly due to the tradeoff between small carrier transport lengths and longer infrared photon absorption lengths. Here, we demonstrate a bottom-illuminated periodic nanostructured CQD solar cell that enhances broadband absorption without compromising charge extraction efficiency of the device. We use finite difference time domain (FDTD) simulations to study the nanostructure for implementation in a realistic device and then build proof-of-concept nanostructured solar cells, which exhibit a broadband absorption enhancement over the wavelength range of λ = 600 to 1,100 nm, leading to a 31% improvement in overall short-circuit current density compared to a planar device containing an approximately equal volume of active material. Remarkably, the improved current density is achieved using a light-absorber volume less than half that typically used in the best planar devices.

  9. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    Science.gov (United States)

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region.

  10. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Directory of Open Access Journals (Sweden)

    Cheng Chuantong

    2017-07-01

    Full Text Available Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  11. Monolithic optoelectronic integrated broadband optical receiver with graphene photodetectors

    Science.gov (United States)

    Cheng, Chuantong; Huang, Beiju; Mao, Xurui; Zhang, Zanyun; Zhang, Zan; Geng, Zhaoxin; Xue, Ping; Chen, Hongda

    2017-07-01

    Optical receivers with potentially high operation bandwidth and low cost have received considerable interest due to rapidly growing data traffic and potential Tb/s optical interconnect requirements. Experimental realization of 65 GHz optical signal detection and 262 GHz intrinsic operation speed reveals the significance role of graphene photodetectors (PDs) in optical interconnect domains. In this work, a novel complementary metal oxide semiconductor post-backend process has been developed for integrating graphene PDs onto silicon integrated circuit chips. A prototype monolithic optoelectronic integrated optical receiver has been successfully demonstrated for the first time. Moreover, this is a firstly reported broadband optical receiver benefiting from natural broadband light absorption features of graphene material. This work is a perfect exhibition of the concept of monolithic optoelectronic integration and will pave way to monolithically integrated graphene optoelectronic devices with silicon ICs for three-dimensional optoelectronic integrated circuit chips.

  12. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.

    1997-01-01

    Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity...... of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....

  13. A broadband Soleil-Babinet compensator for ultrashort light pulses

    Science.gov (United States)

    Xu, Shixiang; Ma, Yingkun; Cai, Yi; Lu, Xiaowei; Zeng, Xuanke; Chen, Hongyi; Li, Jingzhen

    2013-12-01

    This letter reports a novel design for a broadband Soleil-Babinet compensator including two pairs of optical wedges plus one plate. According to our birefringent dispersion compensation model, we can eliminate the first-order birefringent phase retardation (BPR) dispersion by using three different birefringent crystals. Our results show a Soleil-Babinet compensator based on a MgF2/ADP/KDP combination can work from 0° to 360° phase compensation with the maximal residual BPR less than 6° within the spectral region from 0.65 to 0.95 μm. The residual BPR of the compensator increases monotonically with the spectral deviation from the designed central wavelength, so our compensator is very suitable to be used for broadband laser pulses with most of their energies around the central wavelengths.

  14. A broadband Soleil–Babinet compensator for ultrashort light pulses

    International Nuclear Information System (INIS)

    Xu, Shixiang; Ma, Yingkun; Cai, Yi; Lu, Xiaowei; Zeng, Xuanke; Chen, Hongyi; Li, Jingzhen

    2013-01-01

    This letter reports a novel design for a broadband Soleil–Babinet compensator including two pairs of optical wedges plus one plate. According to our birefringent dispersion compensation model, we can eliminate the first-order birefringent phase retardation (BPR) dispersion by using three different birefringent crystals. Our results show a Soleil–Babinet compensator based on a MgF 2 /ADP/KDP combination can work from 0° to 360° phase compensation with the maximal residual BPR less than 6° within the spectral region from 0.65 to 0.95 μm. The residual BPR of the compensator increases monotonically with the spectral deviation from the designed central wavelength, so our compensator is very suitable to be used for broadband laser pulses with most of their energies around the central wavelengths. (letter)

  15. The representation of neutron polarization

    International Nuclear Information System (INIS)

    Byrne, J.

    1979-01-01

    Neutron beam polarization representation is discussed under the headings; transfer matrices, coherent parity violation for neutrons, neutron spin rotation in helical magnetic fields, polarization and interference. (UK)

  16. Comparison of VP broadband tiltmeter and VS vertical pendulum tiltmeter

    OpenAIRE

    Ma, Wugang; Wu, Yanxia; Zhao, Huiqin

    2015-01-01

    Vertical pendulum (VP) tiltmeter is a kind of earthquake precursor observation equipment, which is used to record the interaction force associated with astronomical tidal tilts caused. Currently, VP broadband tiltmeter and vertical sensor (VS) vertical pendulum tiltmeter are primarily used. In this paper, we compare the two different instruments by using four aspects—mechanical structure, circuitry, zeroing, and bandwidth—based on their working principles and applications. We conclude that VP...

  17. Economists' Statement on U.S. Broadband Policy

    OpenAIRE

    Kahn, Alfred E.; Goolsbee, Austan; Bailey, Elizabeth E.; Faulhaber, Gerald R.; Mayo, John; Flamm, Kenneth; Baily, Martin Neil; Milgrom, Paul; Cramton, Peter; Gilbert, Richard; Hall, Robert E.; Litan, Robert E.; Hahn, Robert W.; Greenstein, Shane; Hazlett, Thomas W.

    2006-01-01

    In this statement, a group of economists assembled by the AEI-Brookings Joint Center makes the following two recommendations to improve the competitive provision of broadband services. First, Congress should eliminate local franchising regulations, which serve as a barrier to new entry. Second, Congress and the Federal Communications Commission should make more spectrum available to private parties and allow them to use it as they see fit or trade their licenses in the market, so that spectru...

  18. Gain-assisted broadband ring cavity enhanced spectroscopy

    Science.gov (United States)

    Selim, Mahmoud A.; Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

    2017-02-01

    Incoherent broadband cavity enhanced spectroscopy can significantly increase the effective path length of light-matter interaction to detect weak absorption lines over broad spectral range, for instance to detect gases in confined environments. Broadband cavity enhancement can be based on the decay time or the intensity drop technique. Decay time measurement is based on using tunable laser source that is expensive and suffers from long scan time. Intensity dependent measurement is usually reported based on broadband source using Fabry-Perot cavity, enabling short measurement time but suffers from the alignment tolerance of the cavity and the cavity insertion loss. In this work we overcome these challenges by using an alignment-free ring cavity made of an optical fiber loop and a directional coupler, while having a gain medium pumped below the lasing threshold to improve the finesse and reduce the insertion loss. Acetylene (C2H2) gas absorption is measured around 1535 nm wavelength using a semiconductor optical amplifier (SOA) gain medium. The system is analyzed for different ring resonator forward coupling coefficient and loses, including the 3-cm long gas cell insertion loss and fiber connector losses used in the experimental verification. The experimental results are obtained for a coupler ratio of 90/10 and a fiber length of 4 m. The broadband source is the amplified spontaneous emission of another SOA and the output is measured using a 70pm-resolution optical spectrum analyzer. The absorption depth and the effective interaction length are improved about an order of magnitude compared to the direct absorption of the gas cell. The presented technique provides an engineering method to improve the finesse and, consequently the effective length, while relaxing the technological constraints on the high reflectivity mirrors and free-space cavity alignment.

  19. Comparison of sine dwell and broadband methods for modal testing

    Science.gov (United States)

    Chen, Jay-Chung

    1989-01-01

    The objectives of modal tests for large complex spacecraft structural systems are outlined. The comparison criteria for the modal test methods, namely, the broadband excitation and the sine dwell methods, are established. Using the Galileo spacecraft modal test and the Centaur G Prime upper stage vehicle modal test as examples, the relative advantage or disadvantage of each method is examined. The usefulness or shortcomings of the methods are given from a practical engineering viewpoint.

  20. On sine dwell or broadband methods for modal testing

    Science.gov (United States)

    Chen, Jay-Chung; Wada, Ben K.

    1987-01-01

    For large, complex spacecraft structural systems, the objectives of the modal test are outlined. Based on these objectives, the comparison criteria for the modal test methods, namely, the broadband excitation and the sine dwell methods are established. Using the Galileo spacecraft modal test and the Centaur G Prime upper stage vehicle modal test as examples, the relative advantages or disadvantages of each method are examined. The usefulness or shortcoming of the methods are given from a practicing engineer's view point.

  1. Long-period pulses in broadband records of near earthquakes

    Czech Academy of Sciences Publication Activity Database

    Zahradník, J.; Plešinger, Axel

    2005-01-01

    Roč. 95, č. 5 (2005), s. 1928-1939 ISSN 0037-1106 R&D Projects: GA ČR GA205/02/0381; GA ČR GA205/03/1047 Grant - others:EC(XE) EVG3-CT-2002-80006 ( MAGMA ) Institutional research plan: CEZ:AV0Z30120515 Keywords : broadband records * near earthquakes * seismic signal Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.772, year: 2005

  2. Entry Threat and Entry Deterrence: The Timing of Broadband Rollout

    OpenAIRE

    Mo Xiao; Peter F. Orazem

    2007-01-01

    Past empirical literature provides strong evidence that competition increases when new firms enter a market. However, rarely have economists been able to examine how competition changes with the threat of entry. This paper uses the evolution of the zip code level market structure of facilities-based broadband providers from 1999 to 2004 to investigate how a firm adjusts its entry strategy when facing the threat of additional entrants. We identify the potential entrant into a local market as t...

  3. A broadband electromagnetic energy harvester with a coupled bistable structure

    OpenAIRE

    Zhu, Dibin; Beeby, Steve

    2013-01-01

    This paper investigates a broadband electromagnetic energy harvester with a coupled bistable structure. Both analytical model and experimental results showed that the coupled bistable structure requires lower excitation force to trigger bistable operation than conventional bistable structures. A compact electromagnetic vibration energy harvester with a coupled bistable structure was implemented and tested. It was excited under white noise vibrations. Experimental results showed that the coupl...

  4. Patterning of graphite nanocones for broadband solar spectrum absorption

    Directory of Open Access Journals (Sweden)

    Yaoran Sun

    2015-06-01

    Full Text Available We experimentally demonstrate a broadband vis-NIR absorber consisting of 300-400 nm nanocone structures on highly oriented pyrolytic graphite. The nanocone structures are fabricated through simple nanoparticle lithography process and analyzed with three-dimensional finite-difference time-domain methods. The measured absorption reaches an average level of above 95% over almost the entire solar spectrum and agrees well with the simulation. Our simple process offers a promising material for solar-thermal devices.

  5. Optimization of broadband semiconductor chirped mirrors with genetic algorithm

    OpenAIRE

    Dems, M.; Wnuk, P.; Wasylczyk, P.; Zinkiewicz, L.; Wojcik-Jedlinska, A.; Reginski, K.; Hejduk, K.; Jasik, A.

    2016-01-01

    Genetic algorithm was applied for optimization of dispersion properties in semiconductor Bragg reflectors for applications in femtosecond lasers. Broadband, large negative group-delay dispersion was achieved in the optimized design: The group-delay dispersion (GDD) as large as −3500 fs2 was theoretically obtained over a 10-nm bandwidth. The designed structure was manufactured and tested, providing GDD −3320 fs2 over a 7-nm bandwidth. The mirror performance was ...

  6. A flexible experimental setup for femtosecond time-resolved broad-band ellipsometry and magneto-optics

    Energy Technology Data Exchange (ETDEWEB)

    Boschini, F.; Hedayat, H.; Piovera, C.; Dallera, C. [Dipartimento di Fisica, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milano (Italy); Gupta, A. [Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Carpene, E., E-mail: ettore.carpene@polimi.it [CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milano (Italy)

    2015-01-15

    A versatile experimental setup for femtosecond time-resolved ellipsometry and magneto-optical Kerr effect measurements in the visible light range is described. The apparatus is based on the pump-probe technique and combines a broad-band probing beam with an intense near-infrared pump. According to Fresnel scattering matrix formalism, the analysis of the reflected beam at different polarization states of the incident probe light allows one to determine the diagonal and the off-diagonal elements of the dielectric tensor in the investigated sample. Moreover, the pump-probe method permits to study the dynamics of the dielectric response after a short and intense optical excitation. The performance of the experimental apparatus is tested on CrO{sub 2} single crystals as a benchmark.

  7. A flexible experimental setup for femtosecond time-resolved broad-band ellipsometry and magneto-optics

    International Nuclear Information System (INIS)

    Boschini, F.; Hedayat, H.; Piovera, C.; Dallera, C.; Gupta, A.; Carpene, E.

    2015-01-01

    A versatile experimental setup for femtosecond time-resolved ellipsometry and magneto-optical Kerr effect measurements in the visible light range is described. The apparatus is based on the pump-probe technique and combines a broad-band probing beam with an intense near-infrared pump. According to Fresnel scattering matrix formalism, the analysis of the reflected beam at different polarization states of the incident probe light allows one to determine the diagonal and the off-diagonal elements of the dielectric tensor in the investigated sample. Moreover, the pump-probe method permits to study the dynamics of the dielectric response after a short and intense optical excitation. The performance of the experimental apparatus is tested on CrO 2 single crystals as a benchmark

  8. Broadband seismic : case study modeling and data processing

    Science.gov (United States)

    Cahyaningtyas, M. B.; Bahar, A.

    2018-03-01

    Seismic data with wide range of frequency is needed due to its close relation to resolution and the depth of the target. Low frequency provides deeper penetration for the imaging of deep target. In addition, the wider the frequency bandwidth, the sharper the wavelet. Sharp wavelet is responsible for high-resolution imaging and is very helpful to resolve thin bed. As a result, the demand for broadband seismic data is rising and it spurs the technology development of broadband seismic in oil and gas industry. An obstacle that is frequently found on marine seismic data is the existence of ghost that affects the frequency bandwidth contained on the seismic data. Ghost alters bandwidth to bandlimited. To reduce ghost effect and to acquire broadband seismic data, lots of attempts are used, both on the acquisition and on the processing of seismic data. One of the acquisition technique applied is the multi-level streamer, where some streamers are towed on some levels of depth. Multi-level streamer will yield data with varied ghost notch shown on frequency domain. If the ghost notches are not overlapping, the summation of multi-level streamer data will reduce the ghost effect. The result of the multi-level streamer data processing shows that reduction of ghost notch on frequency domain indeed takes place.

  9. Broadband illumination of superconducting pair breaking photon detectors

    International Nuclear Information System (INIS)

    Guruswamy, T; Goldie, D J; Withington, S

    2016-01-01

    Understanding the detailed behaviour of superconducting pair breaking photon detectors such as Kinetic Inductance Detectors (KIDs) requires knowledge of the nonequilibrium quasiparticle energy distributions. We have previously calculated the steady state distributions resulting from uniform absorption of monochromatic sub gap and above gap frequency radiation by thin films. In this work, we use the same methods to calculate the effect of illumination by broadband sources, such as thermal radiation from astrophysical phenomena or from the readout system. Absorption of photons at multiple above gap frequencies is shown to leave unchanged the structure of the quasiparticle energy distribution close to the superconducting gap. Hence for typical absorbed powers, we find the effects of absorption of broadband pair breaking radiation can simply be considered as the sum of the effects of absorption of many monochromatic sources. Distribution averaged quantities, like quasiparticle generation efficiency η, match exactly a weighted average over the bandwidth of the source of calculations assuming a monochromatic source. For sub gap frequencies, however, distributing the absorbed power across multiple frequencies does change the low energy quasiparticle distribution. For moderate and high absorbed powers, this results in a significantly larger η–a higher number of excess quasiparticles for a broadband source compared to a monochromatic source of equal total absorbed power. Typically in KIDs the microwave power absorbed has a very narrow bandwidth, but in devices with broad resonance characteristics (low quality factors), this increase in η may be measurable. (paper)

  10. Near-perfect broadband absorption from hyperbolic metamaterial nanoparticles

    Science.gov (United States)

    Riley, Conor T.; Smalley, Joseph S. T.; Brodie, Jeffrey R. J.; Fainman, Yeshaiahu; Sirbuly, Donald J.; Liu, Zhaowei

    2017-02-01

    Broadband absorbers are essential components of many light detection, energy harvesting, and camouflage schemes. Current designs are either bulky or use planar films that cause problems in cracking and delamination during flexing or heating. In addition, transferring planar materials to flexible, thin, or low-cost substrates poses a significant challenge. On the other hand, particle-based materials are highly flexible and can be transferred and assembled onto a more desirable substrate but have not shown high performance as an absorber in a standalone system. Here, we introduce a class of particle absorbers called transferable hyperbolic metamaterial particles (THMMP) that display selective, omnidirectional, tunable, broadband absorption when closely packed. This is demonstrated with vertically aligned hyperbolic nanotube (HNT) arrays composed of alternating layers of aluminum-doped zinc oxide and zinc oxide. The broadband absorption measures >87% from 1,200 nm to over 2,200 nm with a maximum absorption of 98.1% at 1,550 nm and remains large for high angles. Furthermore, we show the advantages of particle-based absorbers by transferring the HNTs to a polymer substrate that shows excellent mechanical flexibility and visible transparency while maintaining near-perfect absorption in the telecommunications region. In addition, other material systems and geometries are proposed for a wider range of applications.

  11. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H B [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  12. Polarized proton colliders

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    High energy polarized beam collisions will open up the unique physics opportunities of studying spin effects in hard processes. This will allow the study of the spin structure of the proton and also the verification of the many well documented expectations of spin effects in perturbative QCD and parity violation in W and Z production. Proposals for polarized proton acceleration for several high energy colliders have been developed. A partial Siberian Snake in the AGS has recently been successfully tested and full Siberian Snakes, spin rotators, and polarimeters for RHIC are being developed to make the acceleration of polarized beams to 250 GeV possible. This allows for the unique possibility of colliding two 250 GeV polarized proton beams at luminosities of up to 2 x 10 32 cm -2 s -1

  13. Plasma polarization spectroscopy

    International Nuclear Information System (INIS)

    Iwamae, Atsushi; Horimoto, Yasuhiro; Fujimoto, Takashi; Hasegawa, Noboru; Sukegawa, Kouta; Kawachi, Tetsuya

    2005-01-01

    The electron velocity distribution function (EVDF) in plasma can be anisotropic in laser-produced plasmas. We have developed a new technique to evaluate the polarization degree of the emission lines in the extreme vacuum ultra violet wavelength region. The polarization of the emission lines and the continuums from the lithium-like nitrogen and from helium- and hydrogen-like carbon in recombining plasma is evaluated. Particle simulation in the velocity space gives the time scale for relaxation of anisotropic EVDFs. (author)

  14. No More Polarization, Please!

    OpenAIRE

    Reinholt, Mia

    2006-01-01

    The organizational science literature on motivation has for long been polarized into two main positions; the organizational economic position focusing on extrinsic motivation and the organizational behavior position emphasizing intrinsic motivation. With the rise of the knowledge economy and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on mot...

  15. Inertial polarization of dielectrics

    OpenAIRE

    Zavodovsky, A. G.

    2011-01-01

    It was proved that accelerated motion of a linear dielectric causes its polarization. Accelerated translational motion of a dielectric's plate leads to the positive charge of the surface facing the direction of motion. Metal plates of a capacitor were used to register polarized charges on a dielectric's surface. Potential difference between the capacitor plates is proportional to acceleration, when acceleration is constant potential difference grows with the increase of a dielectric's area, o...

  16. The Polarization of Achernar

    Science.gov (United States)

    McDavid, D.

    2005-11-01

    Recent near-infrared measurements of the angular diameter of Achernar (the bright Be star alpha Eridani) with the ESO VLT interferometer have been interpreted as the detection of an extremely oblate photosphere, with a ratio of equatorial to polar radius of at least 1.56 ± 0.05 and a minor axis orientation of 39° ± 1° (from North to East). The optical linear polarization of this star during an emission phase in 1995 September was 0.12 ± 0.02% at position angle 37° ± 8° (in equatorial coordinates), which is the direction of the projection of the rotation axis on the plane of the sky according to the theory of polarization by electron scattering in an equatorially flattened circumstellar disk. These two independent determinations of the orientation of the rotation axis are therefore in agreement. The observational history of correlations between Hα emission and polarization as found in the literature is that of a typical Be star, with the exception of an interesting question raised by the contrast between Schröder's measurement of a small polarization perpendicular to the projected rotation axis in 1969--70 and Tinbergen's measurement of zero polarization in 1974.5, both at times when emission was reportedly absent.

  17. Data Quality Control of the French Permanent Broadband Network in the RESIF Framework.

    Science.gov (United States)

    Grunberg, M.; Lambotte, S.; Engels, F.

    2014-12-01

    In the framework of the RESIF (Réseau Sismologique et géodésique Français) project, a new information system is setting up, allowing the improvement of the management and the distribution of high quality data from the different elements of RESIF. Within this information system, EOST (in Strasbourg) is in charge of collecting real-time permanent broadband seismic waveform, and performing Quality Control on these data. The real-time and validated data set are pushed to the French National Distribution Center (Isterre/Grenoble) to make them publicly available. Furthermore EOST hosts the BCSF-ReNaSS, in charge of the French metropolitan seismic bulletin. This allows to benefit from some high-end quality control based on the national and world-wide seismicity. Here we present the real-time seismic data flow from the stations of the French National Broad Band Network to EOST, and then, the data Quality Control procedures that were recently installed, including some new developments.The data Quality Control consists in applying a variety of processes to check the consistency of the whole system from the stations to the data center. This allows us to verify that instruments and data transmission are operating correctly. Moreover, time quality is critical for most of the scientific data applications. To face this challenge and check the consistency of polarities and amplitudes, we deployed several high-end processes including a noise correlation procedure to check for timing accuracy (intrumental time errors result in a time-shift of the whole cross-correlation, clearly distinct from those due to change in medium physical properties), and a systematic comparison of synthetic and real data for teleseismic earthquakes of magnitude larger than 6.5 to detect timing errors as well as polarity and amplitude problems.

  18. Fusion of a polarized projectile with a polarized target

    International Nuclear Information System (INIS)

    Christley, J.A.; Johnson, R.C.; Thompson, I.J.

    1995-01-01

    The fusion cross sections for a polarized target with both unpolarized and polarized projectiles are studied. Expressions for the observables are given for the case when both nuclei are polarized. Calculations for fusion of an aligned 165 Ho target with 16 O and polarized 7 Li beams are presented

  19. Calculation of femtosecond pulse laser induced damage threshold for broadband antireflective microstructure arrays.

    Science.gov (United States)

    Jing, Xufeng; Shao, Jianda; Zhang, Junchao; Jin, Yunxia; He, Hongbo; Fan, Zhengxiu

    2009-12-21

    In order to more exactly predict femtosecond pulse laser induced damage threshold, an accurate theoretical model taking into account photoionization, avalanche ionization and decay of electrons is proposed by comparing respectively several combined ionization models with the published experimental measurements. In addition, the transmittance property and the near-field distribution of the 'moth eye' broadband antireflective microstructure directly patterned into the substrate material as a function of the surface structure period and groove depth are performed by a rigorous Fourier model method. It is found that the near-field distribution is strongly dependent on the periodicity of surface structure for TE polarization, but for TM wave it is insensitive to the period. What's more, the femtosecond pulse laser damage threshold of the surface microstructure on the pulse duration taking into account the local maximum electric field enhancement was calculated using the proposed relatively accurate theoretical ionization model. For the longer incident wavelength of 1064 nm, the weak linear damage threshold on the pulse duration is shown, but there is a surprising oscillation peak of breakdown threshold as a function of the pulse duration for the shorter incident wavelength of 532 nm.

  20. Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution.

    Science.gov (United States)

    Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

    2016-05-26

    Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.