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4 Oct 2004

Volume 85, Issue 14, pp. 2679-2983

Issue Cover Spotlight Figure

Appl. Phys. Lett. 85, 2860 (2004); http://dx.doi.org/10.1063/1.1799245 (3 pages)

Priya Mahadevan and Alex Zunger
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Miniaturization and embedding of soliton-based electro-optically addressable photonic arrays

A. D’Ercole, E. Palange, E. DelRe, A. Ciattoni, B. Crosignani, and A. J. Agranat

Appl. Phys. Lett. 85, 2679 (2004); http://dx.doi.org/10.1063/1.1795359 (3 pages) | Cited 32 times

Online Publication Date: 14 October 2004

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We achieved the soliton-based miniaturized integration of electro-optic devices in a photorefractive paraelectric bulk crystal, by driving self-trapping through an external bias field in a top-sided electrode geometry. The ensuing spatially resolved electric field manifests a localized voltage-dependent region in which a quasi-uniform field leads to screening-like self-trapped waves at considerably low voltages without sample miniaturization, along with their electro-optic beam manipulation. By replicating the electrode structure, our achievements constitute the basic building block that paves the way to digitally addressable volume photonic manipulator arrays.
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42.65.Tg Optical solitons; nonlinear guided waves
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Jq Electro-optical effects

Experimental demonstration of Bloch mode parity change in photonic crystal waveguide

B. Cluzel, D. Gérard, E. Picard, T. Charvolin, V. Calvo, E. Hadji, and F. de Fornel

Appl. Phys. Lett. 85, 2682 (2004); http://dx.doi.org/10.1063/1.1795370 (3 pages) | Cited 15 times

Online Publication Date: 14 October 2004

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We experimentally show coupling between two photonic crystal waveguide Bloch modes having a different parity. A monomode ridge waveguide etched in a silicon-on-insulator substrate and connecting to the photonic crystal waveguide allows us to excite the even Bloch mode. Transmission measurements, performed on a broad spectral range, show the even mode propagation along the defect line. Then, spectrally resolved near-field patterns obtained by using a scanning near-field optical microscope in collection mode for wavelengths, inside and outside the multimode region of the photonic crystal waveguide, clearly demonstrate coupling phenomenon between even and odd modes.
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42.79.Gn Optical waveguides and couplers
42.70.Qs Photonic bandgap materials
68.37.Uv Near-field scanning microscopy and spectroscopy

Site-selective 900 nm quasi-three-level laser emission in Nd-doped strontium lanthanum aluminate

G. Aka, D. Vivien, and V. Lupei

Appl. Phys. Lett. 85, 2685 (2004); http://dx.doi.org/10.1063/1.1799243 (3 pages) | Cited 3 times

Online Publication Date: 14 October 2004

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Neodymium-doped strontium lanthanum aluminate crystals Sr1−xLax−yNdyMgxAl12-xO19 contain two structural Nd centers with slightly different spectroscopic properties, whose proportion is determined by the composition parameter x. By choosing a composition with x=0.4, which grants the dominance of one of these centers (the center C1), whose properties are suitable for quasi-three-level Nd laser scheme, efficient 901 nm continuous-wave laser emission (slope efficiency ∼0.74) was obtained under 792 nm Ti:sapphire laser pumping. Preliminary experiments evidence the possibility of obtaining 450.5 nm radiation by frequency doubling. Owing to the large absorption linewidth (∼4 nm) this crystal shows good prospect for diode laser pumping.
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42.55.Rz Doped-insulator lasers and other solid state lasers

Microlens reflector for out-of-plane optical coupling of a waveguide to a buried silicon photodiode

Menachem Nathan

Appl. Phys. Lett. 85, 2688 (2004); http://dx.doi.org/10.1063/1.1803617 (3 pages) | Cited 1 time

Online Publication Date: 14 October 2004

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A photoresist microlens is shown to be an extremely efficient reflective element for out-of-plane coupling of light from a negative epoxy-based photoresist (SU8) optical waveguide into a buried silicon pn photodetector. Experimentally determined coupling efficiencies are given for integrated waveguide∕photodetector and waveguide∕microlens∕photodetector structures. The highest measured coupling efficiency in a structure with a 40 μm diameter, 13 μm high microlens is about 74%, versus an average of about 11% in structures without a microlens. The measured microlens-mediated coupling efficiency is in satisfactory agreement with a simple ray tracing simulation that provides a calculated value of 77.5% for the coupling efficiency.
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42.79.Gn Optical waveguides and couplers
85.60.Dw Photodiodes; phototransistors; photoresistors
42.79.Bh Lenses, prisms and mirrors
85.40.Hp Lithography, masks and pattern transfer
42.15.Dp Wave fronts and ray tracing
42.82.Et Waveguides, couplers, and arrays

Cholesteric liquid-crystal laser as an optic fiber-based temperature sensor

M. F. Moreira, I. C. S. Carvalho, W. Cao, C. Bailey, B. Taheri, and P. Palffy-Muhoray

Appl. Phys. Lett. 85, 2691 (2004); http://dx.doi.org/10.1063/1.1781363 (3 pages) | Cited 34 times

Online Publication Date: 14 October 2004

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In this work, we have studied the temperature dependence of a cholesteric liquid-crystal laser coupled to an optical fiber, with a view towards optical fiber sensor applications. To stabilize the laser emission, we developed a procedure to align the liquid crystal placed in the fiber. Unexpected oscillations in the laser emission were observed as the temperature was varied, which can be understood in terms of the competition between bulk and surface anchoring torques.
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42.70.Df Liquid crystals
42.81.Pa Sensors, gyros
07.20.Dt Thermometers
42.55.Mv Dye lasers

Competing terahertz radiation mechanisms in semi-insulating InP at high-density excitation

M. Nakajima, Y. Oda, and T. Suemoto

Appl. Phys. Lett. 85, 2694 (2004); http://dx.doi.org/10.1063/1.1796532 (3 pages) | Cited 12 times

Online Publication Date: 14 October 2004

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The excitation density dependence of the terahertz radiation from a semi-insulating InP surface was investigated in detail. By changing the excitation density, substantial changes were observed in the wave form with a reversal of the polarity of the radiation field. Different azimuthal angle dependence was also observed for low- and high-density excitations. These facts indicate that three different radiation mechanisms coexist and that the dominant radiation mechanism changes with increasing the excitation density from the drift current, for low-excitation density, to the diffusion current and the optical rectification, for high-excitation density.
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42.65.Re Ultrafast processes; optical pulse generation and pulse compression
78.47.-p Spectroscopy of solid state dynamics
68.47.Fg Semiconductor surfaces

1.55 μm Ge islands resonant-cavity-enhanced detector with high-reflectivity bottom mirror

C. B. Li, R. W. Mao, Y. H. Zuo, L. Zhao, W. H. Shi, L. P. Luo, B. W. Cheng, J. Z. Yu, and Q. M. Wang

Appl. Phys. Lett. 85, 2697 (2004); http://dx.doi.org/10.1063/1.1801166 (3 pages) | Cited 6 times

Online Publication Date: 14 October 2004

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A 1.55 μm Ge islands resonant-cavity-enhanced (RCE) detector with high-reflectivity bottom mirror was fabricated by a simple method. The bottom mirror was deposited in the hole formed by anisotropically etching in a basic solution from the back side of the sample with the buried SiO2 layer in silicon-on-insulator substrate as the etch-stop layer. Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2–1.65 μm. The peak responsivity of the RCE detector at 1543.8 nm is 0.028 mA∕W and a full width at half maximum of 5 nm is obtained. Compared with the conventional p-i-n photodetector, the responsivity of RCE detector has a nearly threefold enhancement.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
81.65.Cf Surface cleaning, etching, patterning

Fabrication of high-resolution zone plates with wideband extreme-ultraviolet holography

Harun H. Solak, Christian David, and Jens Gobrecht

Appl. Phys. Lett. 85, 2700 (2004); http://dx.doi.org/10.1063/1.1803937 (3 pages) | Cited 6 times

Online Publication Date: 14 October 2004

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We report an achromatic holographic method to fabricate high-resolution x-ray optics using coherent extreme-ultraviolet radiation from an undulator source. The interference pattern between two spherical beams, which are created using Fresnel zone plates, is recorded to produce a higher-resolution zone plate. Analytical and simulation results showing the formation of the zone plate pattern was confirmed experimentally with the production and testing of a lens with 60-nm outermost zone width. The combination of extreme-ultraviolet light, which exposes photoresists with practically no proximity effect, and holography, which guarantees the accurate placement of zones, addresses the main difficulties faced in the improvement of the resolution of x-ray lenses. Holography with extreme-ultraviolet light has the potential to produce lenses with sub-10-nm resolution.
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07.85.-m X- and γ-ray instruments
41.50.+h X-ray beams and x-ray optics
42.40.Kw Holographic interferometry; other holographic techniques
42.79.Ci Filters, zone plates, and polarizers
42.40.Lx Diffraction efficiency, resolution, and other hologram characteristics

Opto-electronic versus electro-optic modulation

A. Passian, A. L. Lereu, E. T. Arakawa, R. H. Ritchie, T. Thundat, and T. L. Ferrell

Appl. Phys. Lett. 85, 2703 (2004); http://dx.doi.org/10.1063/1.1804252 (3 pages) | Cited 5 times

Online Publication Date: 14 October 2004

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We present a nonlinear modulation scheme based on coupling between optically excited surface plasmons in a thin gold film and the heating of the film by a pulsed direct current, and also for the reverse process. The reflected surface-plasmon excitation beam is shown to undergo a spatial deformation as a function of a pulsed current through the foil. Similarly, the current through the thin film is modulated by the action of periodic excitation of surface plasmons using infrared photons.
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73.61.At Metal and metallic alloys
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.38.-k Polarons and electron-phonon interactions
78.66.Bz Metals and metallic alloys

Temporal and noise characteristics of continuous-wave-pumped continuum generation in holey fibers around 1300 nm

C. J. S. de Matos, S. V. Popov, and J. R. Taylor

Appl. Phys. Lett. 85, 2706 (2004); http://dx.doi.org/10.1063/1.1801175 (3 pages) | Cited 11 times

Online Publication Date: 14 October 2004

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The noise of continuous-wave-pumped broadband continua generated in a holey fiber is characterized in two different all-fiber configurations. An amplified spontaneous emission seeded ytterbium-doped fiber source and fiber Bragg grating based Yb laser were employed to initiate Raman-soliton continuum generation in 100 m of anomalously dispersive holey fiber with spectral width of 300 nm and spectral power density over 10 mW/nm. Low noise operation makes these sources suitable for optical coherence tomography applications.
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78.45.+h Stimulated emission
42.79.Dj Gratings
42.65.Tg Optical solitons; nonlinear guided waves
42.81.Dp Propagation, scattering, and losses; solitons
78.30.Hv Other nonmetallic inorganics
42.25.Kb Coherence
42.55.Wd Fiber lasers

Recovering image resolution in reconstructing digital off-axis holograms by Fresnel-transform method

Pietro Ferraro, Sergio De Nicola, Andrea Finizio, Giovanni Pierattini, and Giuseppe Coppola

Appl. Phys. Lett. 85, 2709 (2004); http://dx.doi.org/10.1063/1.1791735 (3 pages) | Cited 21 times

Online Publication Date: 14 October 2004

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The resolution of amplitude and phase reconstruction of images from digital holograms by the Fresnel transformation method is limited by the pixel width in the reconstructed image plane. The reconstruction pixel depends on distance, wavelength, and number of pixels in the hologram. The spatial frequencies, in the reconstructed image, are band limited by the size of the reconstruction pixel. Undersampling can occur, in the image plane, in the reconstructed amplitude and/or wrapped phase maps. Recovery of reconstructed undersampled spatial frequencies, is possible by the fictitious enlargement of the digital hologram. Correct profile reconstruction of a silicon microelectromechanical structure is demonstrated, applying the proposed method.
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42.40.Jv Computer-generated holograms
42.30.Wb Image reconstruction; tomography
42.30.Va Image forming and processing

High-temperature annealing and optical activation of Eu-implanted GaN

K. Lorenz, U. Wahl, E. Alves, S. Dalmasso, R. W. Martin, K. P. O'Donnell, S. Ruffenach, and O. Briot

Appl. Phys. Lett. 85, 2712 (2004); http://dx.doi.org/10.1063/1.1801686 (3 pages) | Cited 34 times

Online Publication Date: 14 October 2004

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Europium was implanted into GaN through a 10 nm thick epitaxially grown AlN layer that protects the GaN surface during the implantation and also serves as a capping layer during the subsequent furnace annealing. Employing this AlN layer prevents the formation of an amorphous surface layer during the implantation. Furthermore, no dissociation of the crystal was observed by Rutherford backscattering and channeling measurements for annealing temperatures up to 1300°C. Remarkably, the intensity of the Eu related luminescence, as measured by cathodoluminescence at room temperature, increases by one order of magnitude within the studied annealing range between 1100 and 1300°C.
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81.05.Ea III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.uj III-V and II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Fd III-V semiconductors

Antenna effects in terahertz apertureless near-field optical microscopy

Kanglin Wang, Daniel M. Mittleman, Nick C. J. van der Valk, and Paul C. M. Planken

Appl. Phys. Lett. 85, 2715 (2004); http://dx.doi.org/10.1063/1.1797554 (3 pages) | Cited 27 times

Online Publication Date: 14 October 2004

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We have performed measurements on terahertz (THz) apertureless near-field microscopy that show that the temporal shape of the observed near-field signals is approximately proportional to the time-integral of the incident field. Associated with this signal change is a bandwidth reduction by approximately a factor of 3 which is observed using both a near-field detection technique and a far-field detection technique. Using a dipole antenna model, it is shown how the observed effects can be explained by the signal filtering properties of the metal tips used in the experiments.
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42.79.-e Optical elements, devices, and systems
07.79.Fc Near-field scanning optical microscopes

Formal description of diffraction in optical systems: Calculations and experimental evidence

Josep Ferré-Borrull and Salvador Bosch

Appl. Phys. Lett. 85, 2718 (2004); http://dx.doi.org/10.1063/1.1801672 (3 pages) | Cited 1 time

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We present a rigorous mathematical formulation of the diffraction process in optical systems, provided the aperture stop is much smaller than the remaining components. This mathematical scheme allows us to develop methods for the exact numerical calculation of the complex amplitude for any optical system consisting of lenses and an aperture stop placed at any space (either input, output, or intermediate). The procedure eliminates the need of using the exit pupil for calculations and evidences the practical inaccuracies that may arise due to the use of the exit pupil. We present several results for a meniscus lens working with an aperture stop placed before the lens, so that the comparison between the standard calculation procedures, our methods, and the experiment is clearly illustrated.
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42.79.Bh Lenses, prisms and mirrors
42.25.Fx Diffraction and scattering

Short cladding-pumped Er∕Yb phosphate fiber laser with 1.5 W output power

L. Li, M. Morrell, T. Qiu, V. L. Temyanko, A. Schülzgen, A. Mafi, D. Kouznetsov, J. V. Moloney, T. Luo, S. Jiang, and N. Peyghambarian

Appl. Phys. Lett. 85, 2721 (2004); http://dx.doi.org/10.1063/1.1798394 (3 pages) | Cited 18 times

Online Publication Date: 14 October 2004

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We report experimental results on a high-power, cladding-pumped, heavily Er∕Yb co-doped phosphate fiber laser of very short length. Up to 1.5 W cw laser power was obtained from an11-cm-long multimode-core active fiber with optimized input and output couplers, when pumped by a 15 W diode laser at 975 nm. The fiber laser was demonstrated at 1535 nm with a linewidth <1.2 nm, and a good beam quality of M2<3.
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42.55.Wd Fiber lasers
81.05.Kf Glasses (including metallic glasses)
42.81.Bm Fabrication, cladding, and splicing
42.81.Qb Fiber waveguides, couplers, and arrays

Quasistatic electric-field-modulated optical pattern transition in a thin nematic liquid-crystal film with a single feedback mirror

Hsu-Kuan Hsu, Yinchieh Lai, and Shu-Hsia Chen

Appl. Phys. Lett. 85, 2724 (2004); http://dx.doi.org/10.1063/1.1795363 (3 pages)

Online Publication Date: 14 October 2004

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We present here the pattern formation in the transverse profile of a continuous-wave laser beam passing through a parallel planar-aligned nematic liquid crystal (NLC) film biased by a quasistatic electric field and then reflected back to the sample cell by a single planar mirror. The effect of the biasing voltage is studied through the ability to change the nonlinearity by modulating the orientation of the NLC molecules electrically. By suitably modulating the quasistatic electric field the optical pattern transition from the hexagon to the roll is achieved. The pattern transition can be explained by the linear stability analysis for the nonlinear liquid crystal film with optical feedback.
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42.70.Df Liquid crystals
42.79.Bh Lenses, prisms and mirrors
42.79.Hp Optical processors, correlators, and modulators
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Channel waveguide lasers in a lead silicate glass fashioned using the extrusion technique

Arshad K. Mairaj, Xian Feng, David P. Shepherd, and Daniel W. Hewak

Appl. Phys. Lett. 85, 2727 (2004); http://dx.doi.org/10.1063/1.1803623 (3 pages) | Cited 3 times

Online Publication Date: 14 October 2004

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We report the use of extrusion for the development of planar buried channel waveguide lasers in a neodymium-doped lead-silicate glass host. The extrusion process was performed at a constant die temperature of 555±10°C, an applied pressure of 1850 N cm−2 and a viscosity of 107.8–107.2 P, respectively. A planar substrate, 10 mm in length cut from the extruded product, had four buried waveguides each with a core size of 8 by 2.5 μm in the horizontal and vertical directions. Optical characterization of this waveguide revealed single-mode laser operation at 1058 nm with a slope efficiency of 40% for an absorbed power of 59.3 mW. The measured device propagation loss was ∼0.3 dB cm−1.
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42.55.Rz Doped-insulator lasers and other solid state lasers
42.79.Gn Optical waveguides and couplers
42.70.Ce Glasses, quartz

Total internal reflection scattering

Marco A. C. Potenza, D. Brogioli, and M. Giglio

Appl. Phys. Lett. 85, 2730 (2004); http://dx.doi.org/10.1063/1.1801681 (3 pages) | Cited 6 times

Online Publication Date: 14 October 2004

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We show that the wave front of a total internal reflected beam is perturbed by fluctuations in the region probed by the evanescent wave, and light is scattered both above and below the critical angle. While singly scattered light is related to the two-dimensional Fourier transform at the boundary, multiply scattered light originating from very turbid samples can appear only below the critical angle. We show that the very weak scattered light above the critical angle is due to a double tunnel effect, and it is solely due to single scattering at the surface. Applications are discussed.
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42.15.Dp Wave fronts and ray tracing
42.25.Fx Diffraction and scattering
42.25.Gy Edge and boundary effects; reflection and refraction
82.70.Kj Emulsions and suspensions

Semiconductor lasers with an inversely biased active region for generation of millimeter wave modulated signals

T. Toda

Appl. Phys. Lett. 85, 2733 (2004); http://dx.doi.org/10.1063/1.1758778 (3 pages)

Online Publication Date: 14 October 2004

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A semiconductor laser structure is proposed to introduce field effects in its active region. It has five layers of p-n-i-p-n with four electrical contacts to the doped layers, where the current injection into an inversely biased active region is based on the operation of two complementary bipolar transistors with their base-collector junction common. The inverse bias is useful to incorporate carrier transfer phenomena like Gunn effect in semiconductor lasers. Our analysis on the proposed lasers shows that its lasing operation is possible while applying a high electric field more than 106 V/m in the carrier transfer domain. © 2004 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
72.20.Ht High-field and nonlinear effects
85.30.Pq Bipolar transistors
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Enhanced generation of fast protons from a polymer-coated metal foil by a femtosecond intense laser field

Hiroaki Kishimura, Hiroto Morishita, Yasuhisa H. Okano, Yasuaki Okano, Yoichiro Hironaka, Ken-ichi Kondo, Kazutaka G. Nakamura, Yuji Oishi, and Koshichi Nemoto

Appl. Phys. Lett. 85, 2736 (2004); http://dx.doi.org/10.1063/1.1803915 (3 pages) | Cited 11 times

Online Publication Date: 14 October 2004

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The results of generation of fast protons from 5-μm-thick copper foil targets by 60 fs laser irradiation at 1.5×1017 W∕cm2 are presented. Both polyvinylmethylether (PVME)-coated and uncoated copper foil targets are examined. Fast protons are measured using a Thomson mass spectrometer and maximum proton energies are 570 and 280 keV for the PVME-coated and the uncoated target, respectively. The intensity of fast protons with energy of 160 keV from the PVME-coated target is approximately 80-fold higher than that from the uncoated target.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Pv Polymers, organic compounds
61.82.Bg Metals and alloys

Nature of high-energy ions in the cathode plasma jet of a vacuum arc with high rate of current rise

I. I. Beilis

Appl. Phys. Lett. 85, 2739 (2004); http://dx.doi.org/10.1063/1.1801171 (2 pages) | Cited 2 times

Online Publication Date: 14 October 2004

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The production mechanism of extremely high-energy (up to 10 keV) ions observed in vacuum arcs having only a few tens of volts of arc voltage was considered. A model was developed for the plasma acceleration in a high-current (≥1 kA) short pulsed (<1 μs) vacuum arc, taking into account the high rate of rise of the spot current (dI∕dt>100 MA∕s). A system of equations, including equations for the cathode spot and the plasma jet, was solved self-consistently with dI∕dt in the range of 0.1–10 GA∕s. It was shown that the plasma could be accelerated to the measured energy in the near spot region due to a gas dynamic mechanism and that the ion energy depends on the ratio of the ion flux to the electron flux. This ratio is determined by the cathode erosion rate. The calculated cathode erosion rate varies from 200 to 10 μg∕C when the ion energy increases from 0.1 to 10 keV and well agrees with measurements.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.25.Fi Transport properties
52.70.Ds Electric and magnetic measurements
52.50.-b Plasma production and heating
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Valence photoelectron spectra of an electron-beam-irradiated C60 film

Jun Onoe, Aiko Nakao, and Akira Hida

Appl. Phys. Lett. 85, 2741 (2004); http://dx.doi.org/10.1063/1.1799229 (3 pages) | Cited 10 times

Online Publication Date: 14 October 2004

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Valence photoelectron spectra of an electron-beam (EB) irradiated C60 film, which exhibited metallic electron-transport properties in air at room temperature, are presented. The electronic structure of the C60 film became closer to that of graphite as the EB-irradiation time increased, and its density of states around the Fermi level was eventually greater than for the graphite. This suggests that the electronic structure of the C60 film changed from a semiconductor to a semimetal and/or metal by EB irradiation. Interestingly, the electronic structure remained metallic even after five days of air exposure, which is the reason for the metallic electron-transport property in our previous report [Appl. Phys. Lett. 82, 595 (2003)].
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79.60.Dp Adsorbed layers and thin films
71.20.Tx Fullerenes and related materials; intercalation compounds
61.80.Fe Electron and positron radiation effects
81.05.ub Fullerenes and related materials

Thin biaxially textured TiN films on amorphous substrates prepared by ion-beam assisted pulsed laser deposition

R. Hühne, S. Fähler, and B. Holzapfel

Appl. Phys. Lett. 85, 2744 (2004); http://dx.doi.org/10.1063/1.1802385 (3 pages) | Cited 11 times

Online Publication Date: 14 October 2004

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Thin TiN films have been grown using reactive ion-beam assisted pulsed laser deposition. The texture development was in situ analyzed using reflection high-energy electron diffraction. Above 300 °C a sharp cube textured nucleation layer is observed using an ion beam with energies above 400 eV under an angle of 45° relative to the substrate normal. The cube texture is not stable during further ion-beam assisted growth but can be preserved using homoepitaxial growth. Resulting films showed an in-plane orientation of about 13°. The texture development can be described in terms of energy considerations and anisotropic sputter rates.
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68.55.A- Nucleation and growth
68.55.-a Thin film structure and morphology
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Fg Pulsed laser ablation deposition
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Photomechanical effect in films of polyvinylidene fluoride

Sergey S. Sarkisov, Michael J. Curley, Aisha Fields, Sergey S. Sarkisov, and Grigory Adamovsky

Appl. Phys. Lett. 85, 2747 (2004); http://dx.doi.org/10.1063/1.1802390 (3 pages) | Cited 6 times

Online Publication Date: 14 October 2004

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Photothermal bending of strips of polyvinylidene fluoride was initiated by a laser beam with a power of a few milliwatts. A bending strip generated a force of 10−4 N that propelled a 1 g oscillating wheel of a mechanical clock. The frequency of photomechanical resonance at pulsed illumination was inversely proportional to the length of the strip. The proposed model explained bending as a result of uneven thermal expansion on opposite sides of the strip. The model predicted, in agreement with experiment, that the force is proportional to beam power and does not depend on the shape or position of the beam in the strip.
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78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
65.40.De Thermal expansion; thermomechanical effects

On the origin of ultrahigh cryogenic strength of nanocrystalline metals

Y. M. Wang and E. Ma

Appl. Phys. Lett. 85, 2750 (2004); http://dx.doi.org/10.1063/1.1799238 (3 pages) | Cited 66 times

Online Publication Date: 14 October 2004

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At liquid nitrogen temperature, the yield strength of nanocrystalline Ni and Co increases by as much as 50%–80% over the already-impressive (∼1 GPa) room-temperature values. This unusual strength ratio as well as the remarkable magnitude of flow stress reached (as high as 2.5 GPa) are unexpected for conventional close-packed pure metals. The strong temperature dependence is attributed to the unusually small activation volume measured in strain rate change tests. Grain boundary dislocation nucleation is proposed as the thermally activated deformation mechanism in nanocrystalline grains.
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81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.46.-w Structure of nanoscale materials
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