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15 Oct 2007

Volume 91, Issue 16, Articles (16xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 91, 162101 (2007); http://dx.doi.org/10.1063/1.2794995 (3 pages)

D. J. Reilly, C. M. Marcus, M. P. Hanson, and A. C. Gossard
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Absolute frequency stabilization of a diode laser to cesium atom-molecular hyperfine transitions via modulating molecules

Jie Ma, Lirong Wang, Yanting Zhao, Liantuan Xiao, and Suotang Jia

Appl. Phys. Lett. 91, 161101 (2007); http://dx.doi.org/10.1063/1.2799250 (3 pages) | Cited 9 times

Online Publication Date: 15 October 2007

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We have demonstrated a robust method of directly stabilizing diode laser frequency to the cesium atom-molecular hyperfine transitions. The trap loss fluorescence spectroscopy was applied to yield the error signal based on modulating molecules with ultralow modulation frequency of 1.2 Hz. The excursions over 300 s of the frequency of the laser were bounded by 1.5 MHz. The root of Allan variance of the error signals reached a minimum of 4.8×10−11 for an averaging time of 100 s.
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33.80.-b Photon interactions with molecules
33.15.Pw Fine and hyperfine structure
33.50.Dq Fluorescence and phosphorescence spectra
42.55.Px Semiconductor lasers; laser diodes

Suppression of longitudinal modes in two-sectioned, coupled-cavity GaAs/(Al,Ga)As terahertz quantum-cascade lasers

M. Giehler, H. Kostial, R. Hey, and H. T. Grahn

Appl. Phys. Lett. 91, 161102 (2007); http://dx.doi.org/10.1063/1.2794008 (3 pages) | Cited 2 times

Online Publication Date: 15 October 2007

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The spectra of two-sectioned, coupled-cavity (TSCC) terahertz quantum-cascade lasers exhibit a number of longitudinal modes, which are periodically suppressed due to interference effects. The number of suppressed modes is equal to the ratio of the lengths of the two subcavities. At maximum laser output, the mode suppression disappears due to optical saturation, and a switching between TSCC and single-cavity-like mode features appears for certain delays between the current pulses through the individual subcavities. A transfer-matrix approach reproduces the mode spacings very well, but predicts a smaller modulation of the mode heights and does not describe the observed mode switching.
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42.55.Px Semiconductor lasers; laser diodes
42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Quantum key distribution using a triggered quantum dot source emitting near 1.3 μm

P. M. Intallura, M. B. Ward, O. Z. Karimov, Z. L. Yuan, P. See, A. J. Shields, P. Atkinson, and D. A. Ritchie

Appl. Phys. Lett. 91, 161103 (2007); http://dx.doi.org/10.1063/1.2799756 (3 pages) | Cited 23 times

Online Publication Date: 15 October 2007

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We report the distribution of a cryptographic key, secure from photon number splitting attacks, over 35 km of optical fiber using single photons from an InAs quantum dot emitting ∼ 1.3 μm in a pillar microcavity. Using below GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton emission to 10% of the Poissonian level without detector dark count subtraction. The source is incorporated into a phase encoded interferometric scheme implementing the BB84 protocol for key distribution over standard telecommunication optical fiber. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at 1310 nm in the same system.
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03.67.Dd Quantum cryptography and communication security
42.50.Ar Photon statistics and coherence theory
07.60.Ly Interferometers
02.50.Ng Distribution theory and Monte Carlo studies
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

InAs/AlAsSb based quantum cascade lasers

X. Marcadet, C. Renard, M. Carras, M. Garcia, and J. Massies

Appl. Phys. Lett. 91, 161104 (2007); http://dx.doi.org/10.1063/1.2790824 (3 pages) | Cited 5 times

Online Publication Date: 15 October 2007

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The advantages and drawbacks of the different semiconductor materials which can be used for the fabrication of quantum cascade laser (QCL) emitting in the 3–4 μm wavelength range bring us to propose a material combination which can be lattice matched to InAs substrate. It is shown that using InAs quantum wells and AlAsSb barriers, it is possible to balance the strain in QCL structures made on InAs whatever the active region design and the wavelength targeted. A first InAs/AlAsSb QCL structure has been grown and fully characterized by x-ray diffraction. The devices emit at 3.5 μm at 300 K in pulsed mode.
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42.55.Px Semiconductor lasers; laser diodes
68.65.Fg Quantum wells
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Femtosecond real-time single-shot digitizer

Jason Chou, Ozdal Boyraz, Daniel Solli, and Bahram Jalali

Appl. Phys. Lett. 91, 161105 (2007); http://dx.doi.org/10.1063/1.2799741 (3 pages) | Cited 27 times

Online Publication Date: 16 October 2007

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We demonstrate a single-shot digitizer with a 10 Tsample/s sampling rate. This feat is accomplished with a photonic time stretch preprocessor that slows down the electrical waveform by an unprecedented factor of 250 before it is captured by a commercial electronic digitizer. To achieve such a large stretch factor, distributed Raman optical amplification is realized inside the dispersive element that performs the time stretch.
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42.55.Ye Raman lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
42.30.-d Imaging and optical processing
42.79.Hp Optical processors, correlators, and modulators
42.55.Wd Fiber lasers

Coherence in Y-coupled quantum cascade lasers

L. K. Hoffmann, C. A. Hurni, S. Schartner, M. Austerer, E. Mujagić, M. Nobile, A. Benz, W. Schrenk, A. M. Andrews, P. Klang, and G. Strasser

Appl. Phys. Lett. 91, 161106 (2007); http://dx.doi.org/10.1063/1.2800293 (3 pages) | Cited 5 times

Online Publication Date: 16 October 2007

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A monolithic coupling scheme in which two active waveguides merge into a single waveguide is presented for a GaAs/AlGaAs quantum cascade laser. The evolving fields interfere and a constant phase is observed in the Y-shaped laser cavity, resulting in a far field pattern of a double slit. The mode distribution is comprehensively derived by matching the far field profiles to simulated values and shows a weak current dependence. The device demonstrates the feasibility of coherent laser resonators with prospective applications in interferometric sensing and high power laser arrays.
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42.55.Px Semiconductor lasers; laser diodes
42.55.Sa Microcavity and microdisk lasers
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Thermo- and photoinduced voltages in Ag heterodimensional junctions

Jia Xu, Jia-Lin Sun, and Jia-Lin Zhu

Appl. Phys. Lett. 91, 161107 (2007); http://dx.doi.org/10.1063/1.2800295 (3 pages) | Cited 8 times

Online Publication Date: 16 October 2007

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Macroscopic-long Ag nanowires have been synthesized through an improved solid-state ionics method and characterized at different spatial scales. Using a bundle of as-fabricated Ag nanowires to connect with two bulk Ag electrodes, two Ag heterodimensional junctions are formed into an electrical circuit. Thermo- and photoinduced electromotive forces are observed and the corresponding voltages are measured in the circuit on the macroscale. For the photoinduced voltage, the fast dynamic response of the circuit, irradiated locally by 532 nm and 10.6 μm lasers, is exhibited. The studied low-dimensional effects need to be taken into account in future applications of Ag nanowires.
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72.15.Jf Thermoelectric and thermomagnetic effects
72.40.+w Photoconduction and photovoltaic effects
73.63.Nm Quantum wires
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Longitudinal spatial hole burning in terahertz quantum cascade lasers

Josef Kröll, Juraj Darmo, Karl Unterrainer, Sukhdeep S. Dhillon, Carlo Sirtori, Xavier Marcadet, and Michel Calligaro

Appl. Phys. Lett. 91, 161108 (2007); http://dx.doi.org/10.1063/1.2747185 (3 pages) | Cited 6 times

Online Publication Date: 16 October 2007

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The propagation of a quasi-single-cycle terahertz pulse through an active terahertz quantum cascade laser is studied. The terahertz pulse is found to be diffracted on the optically induced longitudinal modulation of the refractive index of the laser active region. This modulation is a result of longitudinal spatial hole burning due to the formation of a standing wave in the laser cavity.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.65.-k Nonlinear optics
42.60.Fc Modulation, tuning, and mode locking
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Optical gain at 1535 nm in LaF3:Er,Yb nanoparticle-doped organic-inorganic hybrid material waveguide

Dan Zhang, Cong Chen, Changming Chen, Chunsheng Ma, Daming Zhang, Shuhui Bo, and Zhen Zhen

Appl. Phys. Lett. 91, 161109 (2007); http://dx.doi.org/10.1063/1.2799582 (3 pages) | Cited 10 times

Online Publication Date: 17 October 2007

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LaF3:Er,Yb nanoparticle-doped organic-inorganic hybrid material waveguides were demonstrated using reactive ion etching technology. The absorption and photoluminescence spectra were observed on a 140 μm thick film of the nanoparticle-doped hybrid material. Under excitation at 976 nm, the fluorescence was obtained at 1535 nm, and its full width at half maximum was about 83 nm. A relative optical gain of about 5 dB was measured at 1535 nm in a 22-mm-long waveguide.
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42.79.Gn Optical waveguides and couplers
81.07.Pr Organic-inorganic hybrid nanostructures
81.65.Cf Surface cleaning, etching, patterning
42.86.+b Optical workshop techniques
42.79.Wc Optical coatings
42.55.Rz Doped-insulator lasers and other solid state lasers
42.70.Hj Laser materials

Boron carbide spherical particles encapsulated in graphite prepared by pulsed laser irradiation of boron in liquid medium

Yoshie Ishikawa, Yoshiki Shimizu, Takeshi Sasaki, and Naoto Koshizaki

Appl. Phys. Lett. 91, 161110 (2007); http://dx.doi.org/10.1063/1.2799786 (3 pages) | Cited 11 times

Online Publication Date: 17 October 2007

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B4C submicron particles were obtained by laser irradiation of B particles in ethyl acetate under atmospheric pressure and room temperature. Absorbed laser energy brought about B melting and decomposition of surrounding liquid medium molecules, leading to a reaction between the melted B and carbon species to form B4C. Moreover, the obtained B4C particles were encapsulated in a graphite layer. Such a graphite surface layer is useful for medical functionalization of particles. Thus, obtained B4C particles encapsulated in graphite are expected to be promising agents for boron neutron capture therapy.
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42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.62.Cf Industrial applications

Influence of InAs, AlAs δ layers on the optical, electronic, and thermal characteristics of strain-compensated GaInAs/AlInAs quantum-cascade lasers

Miriam S. Vitiello, Tobias Gresch, Antonia Lops, Vincenzo Spagnolo, Gaetano Scamarcio, Nicolas Hoyler, Marcella Giovannini, and Jérôme Faist

Appl. Phys. Lett. 91, 161111 (2007); http://dx.doi.org/10.1063/1.2798061 (3 pages) | Cited 14 times

Online Publication Date: 17 October 2007

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We extracted the electronic temperatures, the thermal resistance (RL = 11.5 K/W), the cross-plane thermal conductivity [k = 2.0±0.1 W/(Km)], and the thermal boundary resistance [TBR = (5–11)×10−10K/Wm2] in strain-compensated Ga0.609In0.391As/AlIn0.546As0.454 quantum-cascade lasers operating at 4.78 μm in continuous wave up to 15 °C and in pulsed mode up to 40 °C. Submonolayer thick InAs and AlAs δ layers are included in the active region to increase the conduction band discontinuity. We found that potential interface broadening caused by the insertion of these δ layers allows for a 60% improvement of the thermal conductivity with respect to conventional lattice-matched GaInAs/AlInAs heterostructures.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

All-optical modulation of laser light in amorphous silicon-filled microstructured optical fibers

Dong-Jin Won, Mariola O. Ramirez, Hoonsoo Kang, Venkatraman Gopalan, Neil F. Baril, Jacob Calkins, John V. Badding, and Pier J. A. Sazio

Appl. Phys. Lett. 91, 161112 (2007); http://dx.doi.org/10.1063/1.2790079 (3 pages) | Cited 14 times

Online Publication Date: 17 October 2007

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Amorphous silicon is deposited within optical fibers by a high pressure microfluidic deposition process and characterized via Raman spectroscopy. All-optical modulation of 1.55 μm light guided through the silicon core is demonstrated using the free carrier absorption generated by a 532 nm pump pulse. Modulation depths of up to 8.26 dB and modulation frequencies of up to 1.4 MHz are demonstrated.
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42.81.Bm Fabrication, cladding, and splicing
42.81.Cn Fiber testing and measurement of fiber parameters
42.81.Dp Propagation, scattering, and losses; solitons
47.85.Np Fluidics

Enhancement and reduction of line broadening due to Auger scattering in modulation-doped InGaAs/GaAs quantum dot devices

H. H. Nilsson, J.-Z. Zhang, and I. Galbraith

Appl. Phys. Lett. 91, 161113 (2007); http://dx.doi.org/10.1063/1.2799244 (3 pages) | Cited 3 times

Online Publication Date: 18 October 2007

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We calculate the line broadening of various Auger processes in modulation-doped InGaAs/GaAs quantum dot (QD) semiconductor optical amplifiers (SOAs), involving scattering of carriers between wetting-layer states and confined QD states. We find that, as a result of p doping, the optical gain and the linewidth are significantly enhanced, while in shallow dots, n doping surprisingly leads to a reduction in the homogeneous linewidth. Our findings support the development of high-speed QD lasers and SOAs incorporating p doping and using optical amplifiers with n-doped shallow QDs for wavelength-division-multiplexing applications.
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78.67.Hc Quantum dots
78.66.Fd III-V semiconductors
73.21.La Quantum dots

Digital resonance tuning of high-Q/Vm silicon photonic crystal nanocavities by atomic layer deposition

Xiaodong Yang, Charlton J. Chen, Chad A. Husko, and Chee Wei Wong

Appl. Phys. Lett. 91, 161114 (2007); http://dx.doi.org/10.1063/1.2800312 (3 pages) | Cited 18 times

Online Publication Date: 18 October 2007

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We propose and demonstrate the digital resonance tuning of high-Q/Vm silicon photonic crystal nanocavities using a self-limiting atomic layer deposition technique. Control of resonances in discrete steps of 122±18 pm/hafnium oxide atomic layer is achieved through this postfabrication process, nearly linear over a full 17 nm tuning range. The cavity Q is maintained in this perturbative process, and can reach up to its initial values of 49 000 or more. Our results are highly controllable, applicable to many material systems, and particularly critical to matching resonances and transitions involving mesoscopic optical cavities.
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42.82.Gw Other integrated-optical elements and systems
42.70.Qs Photonic bandgap materials
42.65.-k Nonlinear optics

Passband filters for terahertz radiation based on dual metallic photonic structures

A. J. Gallant, M. A. Kaliteevski, D. Wood, M. C. Petty, R. A. Abram, S. Brand, G. P. Swift, D. A. Zeze, and J. M. Chamberlain

Appl. Phys. Lett. 91, 161115 (2007); http://dx.doi.org/10.1063/1.2800381 (3 pages) | Cited 8 times

Online Publication Date: 18 October 2007

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This paper reports on the development of two-dimensional metallic microstructures for the filtering of terahertz radiation. These structures are fabricated using ultraviolet-based processing of thick SU8 resist. This micromachining technique enables the array patterns, dimensions, and consequently the filter characteristics to be readily defined. In particular, we demonstrate that a filter with an isolated near-square-shaped passband can be realized on the basis of a combination of two different metallic photonic arrays of optimized design.
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42.79.Ci Filters, zone plates, and polarizers
84.40.-x Radiowave and microwave (including millimeter wave) technology
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Lasing in electrodeposited ZnO inverse opal

L. K. Teh, C. C. Wong, H. Y. Yang, S. P. Lau, and S. F. Yu

Appl. Phys. Lett. 91, 161116 (2007); http://dx.doi.org/10.1063/1.2801358 (3 pages) | Cited 15 times

Online Publication Date: 19 October 2007

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We report room-temperature ultraviolet lasing in ZnO inverse opals fabricated via colloidal templating with electrochemical infiltration. Lasing occurs above an excitation threshold of 0.38 MW/cm2. Lasing modes associated with radiative recombinations of exciton-exciton (ex-ex) and electron-hole plasma (EHP) were discerned. Compared to ZnO polycrystalline film, lasing wavelength blueshifts and ex-ex lasing with a narrower bandwidth have been realized. Tuning the primary photonic pseudogap of inverse opals to gain maximum reduces the threshold for EHP lasing. We infer that periodic structures facilitate strain-induced change in lasing energy and provide modulation in refractive index for enhanced light confinement as well as optical feedback.
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42.55.Rz Doped-insulator lasers and other solid state lasers
71.35.Ee Electron-hole drops and electron-hole plasma
42.70.Qs Photonic bandgap materials
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Continuum visible spectra from InBr discharge excited in a microwave resonant cavity

Yuming Chen and Dahua Chen

Appl. Phys. Lett. 91, 161501 (2007); http://dx.doi.org/10.1063/1.2799167 (2 pages) | Cited 1 time

Online Publication Date: 15 October 2007

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Emissions from InBr radiation have been investigated in a microwave resonant cavity system. We demonstrate that with proper operation the emission spectra of InBr can be a continuum in the visible range and can be suitable for lighting applications. The continuum spectra are stronger with an increase in input microwave power. In our system, a high color rendering index of 97 can be obtained from the bulb with 25 mg InBr and 800 W input microwave power. The spectral lines 410.1 and 451.1 nm from In I play an important role to balance the spectral distribution for lighting requirements. The continuum spectra may be due to the transition of Rydberg states to the C state of InBr molecules.
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78.40.Fy Semiconductors
78.55.Hx Other solid inorganic materials

Simulated experiment for elimination of air contaminated with odorous chemical agents by microwave plasma burner

Yong Cheol Hong, Dong Hun Shin, and Han Sup Uhm

Appl. Phys. Lett. 91, 161502 (2007); http://dx.doi.org/10.1063/1.2800302 (3 pages) | Cited 5 times

Online Publication Date: 16 October 2007

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An experimental study on elimination of odorous chemical agent was carried out by making use of a microwave plasma burner, which consists of a microwave plasma torch and a reaction chamber with a fuel injector. Injection of hydrocarbon fuels into a high-temperature microwave torch plasma generates a plasma flame. The plasma flame can eliminate the odorous chemical agent diluted in air or purify the interior air of a large volume in isolated spaces. The specially designed reaction chamber eliminated H2S and NH3 diluted in airflow rate of 5000 lpm (liters per minute), showing β values of 46.52 and 39.69 J/l, respectively.
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52.75.Hn Plasma torches
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.70.Gw Radio-frequency and microwave measurements

Anomalous absorption of surface plasma wave by particles adsorbed on metal surface

Gagan Kumar and V. K. Tripathi

Appl. Phys. Lett. 91, 161503 (2007); http://dx.doi.org/10.1063/1.2800305 (3 pages) | Cited 6 times

Online Publication Date: 18 October 2007

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A surface plasma wave (SPW) propagating on a metal surface, covered with thin layer of metallic nanoparticles, excites resonant plasma oscillations in the particles. The particles absorb energy from the wave via electrons, incurring attenuation of the surface plasma wave. For spherical metallic particles with plasma frequency ωPe, the resonant plasma oscillations occur at ω = ωPe/math, where ω is the frequency of the SPW. In the vicinity of this frequency, a sharp increase in the absorption of surface plasma wave by the metallic particles, depending upon its size, occurs.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.68.+m Optical properties of surfaces

Carbon fiber-based cathodes for magnetically insulated transmission line oscillator operation

Lie Liu, Limin Li, Xiaoping Zhang, Jianchun Wen, Hong Wan, and Huihuang Zhong

Appl. Phys. Lett. 91, 161504 (2007); http://dx.doi.org/10.1063/1.2801389 (3 pages) | Cited 6 times

Online Publication Date: 19 October 2007

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We report experimental results of carbon fiber cathodes for the magnetically insulated transmission line oscillator (MILO). The fabrication process of carbon fiber cathodes is presented. In experiments employing a 500 kV, 100 ns high-voltage pulsed accelerator, microwave generation in the C band was obtained with ∼ 900 MW peak power and ∼ 20 ns pulse width at about 4.5% efficiency. The MILO operation exhibited high stability by using carbon fiber cathodes. These results show that carbon fiber cathodes can offer promising applications for high performance MILOs.
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84.40.-x Radiowave and microwave (including millimeter wave) technology

Laser-induced fluorescence measurements in an inductively coupled plasma reactor

Brett Jacobs, Walter Gekelman, Pat Pribyl, Michael Barnes, and Michael Kilgore

Appl. Phys. Lett. 91, 161505 (2007); http://dx.doi.org/10.1063/1.2801393 (3 pages) | Cited 6 times

Online Publication Date: 19 October 2007

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The authors report on laser-induced fluorescence (LIF) measurements of ion velocity distribution functions made in an inductively coupled plasma reactor with a pulsed plasma source. Vertical and radial velocities have been measured at thousands of spatial locations within a plane, and the LIF data have been calibrated to a 96 GHz microwave interferometer. The ions are observed to approach the Bohm velocity and the inferred electric potential within the presheath agrees well with theory. A two-dimensional flow pattern of the ion velocity above the substrate is presented.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.75.-d Plasma devices

High-density energy conversion using compact magnetohydrodynamic electrical power generator

Tomoyuki Murakami and Yoshihiro Okuno

Appl. Phys. Lett. 91, 161506 (2007); http://dx.doi.org/10.1063/1.2800785 (3 pages) | Cited 7 times

Online Publication Date: 19 October 2007

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We describe high-density energy conversion using a compact closed-cycle magnetohydrodynamic electrical power generator. The slightly divergent disk-shaped generator exhibits improved energy-conversion performance, in particular, a high power density of 0.76 GW/m3. The application of high- and uniform-density magnetic flux to the entire generator, the high electrical conductivity, the symmetric plasma structure and stable plasma behavior, and the sufficient pressure gradient used to drive the fluid contribute to the outstanding performance of the generator.
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84.60.Lw Magnetohydrodynamic conversion
52.75.Fk Magnetohydrodynamic generators and thermionic convertors; plasma diodes

A simple device of generating glow discharge plasma in atmospheric pressure argon

Xuechen Li, Lifang Dong, Na Zhao, Zengqian Yin, Tongzhen Fang, and Long Wang

Appl. Phys. Lett. 91, 161507 (2007); http://dx.doi.org/10.1063/1.2800814 (3 pages) | Cited 10 times

Online Publication Date: 19 October 2007

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Atmospheric pressure glow discharge is realized in argon by using a plasma needle. With increasing the applied voltage, uniform plasma increases in scale from a small region near the needle tip to a plasma plume with a length of about 20 mm. The discharge mechanism is discussed based on the light emission waveforms from the plasma. Optical emission spectroscopy is used to determine excited electron temperature and vibrational temperature, and the results indicate that the excited electron temperature and the molecular vibrational temperature are about 6000 and 2300 K, respectively.
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52.80.Hc Glow; corona
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
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Surface elastic properties of porous nanosilica coatings by scanning force microscopy

A. Vincent, S. Babu, and S. Seal

Appl. Phys. Lett. 91, 161901 (2007); http://dx.doi.org/10.1063/1.2799249 (3 pages) | Cited 3 times

Online Publication Date: 15 October 2007

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Surface elastic properties of sol-gel derived porous nanosilica optical coatings were determined using scanning force microscopy. Silica nanocoatings prepared under acid and base catalyzed sol-gel process exhibited varying surface morphology, particle size and porosity. Force-distance spectroscopy measurements were conducted on these coatings using scanning force microscopy, and their elastic moduli were obtained by applying Hertz model. The elastic modulus of the coatings varied from 2.4 to 13.4 GPa depending on the nature and concentration of the catalyst used.
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68.60.Bs Mechanical and acoustical properties
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.35.Gy Mechanical properties; surface strains
61.46.-w Structure of nanoscale materials

Probing the phase composition of silicon films in situ by etch product detection

G. Dingemans, M. N. van den Donker, A. Gordijn, W. M. M. Kessels, and M. C. M. van de Sanden

Appl. Phys. Lett. 91, 161902 (2007); http://dx.doi.org/10.1063/1.2799738 (3 pages) | Cited 8 times

Online Publication Date: 15 October 2007

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Exploiting the higher etch probability for amorphous silicon relative to crystalline silicon, the transiently evolving phase composition of silicon films in the microcrystalline growth regime was probed in situ by monitoring the etch product (SiH4) gas density during a short H2 plasma treatment step. Etch product detection took place by the easy-to-implement techniques of optical emission spectroscopy and infrared absorption spectroscopy. The phase composition of the films was probed as a function of the SiH4 concentration during deposition and as a function of the film thickness. The in situ results were corroborated by Raman spectroscopy and solar cell analysis.
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68.55.Nq Composition and phase identification
68.55.-a Thin film structure and morphology
68.55.A- Nucleation and growth
64.70.K- Solid-solid transitions
81.65.Cf Surface cleaning, etching, patterning
81.15.Jj Ion and electron beam-assisted deposition; ion plating
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