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Applied Physics Letters Collection (91 Books)


 
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Applied Physics Letters : Influence of polarity on carrier transpo...

By: Yoshinobu Kawaguchi, Chia-Yen Huang, Yuh-Renn Wu, Qimin Yan, Chih-Chien Pan et al

Description: We investigate the influence of polarity on carrier transport in single-quantum-well and multiple-quantum-well (MQW) light-emitting diodes (LEDs) grown on the semipolar (20¯21) and (20¯21) orientations of free-standing GaN. For semipolar MQW LEDs with the opposite polarity to conventional Ga-polar c-plane LEDs, the polarization-related electric field in the QWs results in an additional energy barrier for carriers to escape the QWs. We show that semipolar (20...

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Applied Physics Letters : Experimental isolation of degradation me...

By: Z. Olszewski, R. Houlihan, C. Ryan, C. OMahony, and R. Duane

Description: DC and bipolar voltage stresses are used to isolate mechanical degradation of the movable electrode from charging mechanism in microelectromechanical capacitive switches. Switches with different metals as the movable electrode were investigated. In titanium switches, a shift in the pull-in voltages is observed after dc stressing whereas no shift occurs after the bipolar stressing, which is to be expected from charging theory. On switches with similar dielect...

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Applied Physics Letters : Photonic integration in k-space: Enhanci...

By: Mads Brøkner Christiansen, Anders Kristensen, Sanshui Xiao, and Niels Asger Mortensen

Description: We demonstrate how two optical functionalities can be implemented in a single photonic crystal structure by carefully engineering dispersion in several different bands at several different wavelengths. We use the concept for optically pumped dye doped hybrid polymer band edge lasers and show how a rectangular photonic crystal lattice imprinted into the surface can provide both feedback for in-plane band edge lasing and couple pump light into the device plane...

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Applied Physics Letters : Terahertz generation in multiple laser-i...

By: Meng-Ku Chen, Jae Hun Kim, Chia-En Yang, Stuart Shizhuo Yin, Rongqing Hui et al

Description: An investigation of the terahertz wave generation in multiple laser-induced air plasmas is presented. First, it is demonstrated that the intensity of the terahertz wave increases as the number of air plasmas increases. Second, the physical mechanism of this enhancement effect of the terahertz generation is studied by quantitatively measuring the intensity of the generated terahertz wave as a function of phase difference between adjacent air plasmas. It is fo...

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Applied Physics Letters : Direct measurement of the complex refrac...

By: B. Mills, C. F. Chau, E. T. F. Rogers, J. Grant-Jacob, S. L. Stebbings et al

Description: Using extreme ultraviolet XUV radiation from a high harmonic source, we observe diffraction from a single-layer self-assembled hexagonal array of 196 1.2 nm diameter polystyrene spheres. The Mie solution is used to predict the correct form factor for a single sphere and hence model the intensities of the observed diffraction peaks for the first three orders. By measuring the diffraction intensities in this way, we demonstrate a technique for obtaining the ...

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Applied Physics Letters : Large cavity quantum cascade lasers with...

By: A. Bismuto, T. Gresch, A. Bächle, and Jérôme Faist

Description: Multicore quantum cascade lasers with large cavities show low optical losses, high saturation intensity, and low beam divergence. We present a four active core laser based on InGaAs–AlInAs material system emitting at 10.5 μm. To improve thermal conductance, InP interstacks were used to separate active regions. Selective lateral etching of the active regions was used to reduce optical losses. Peak powers up to 4.6 W, average powers up to 310 mW, and wall-plu...

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Applied Physics Letters : Plasmonic photonic crystal with a comple...

By: Liang Feng, Ming-Hui Lu, Vitaliy Lomakin, and Yeshaiahu Fainman

Description: A dielectric plasmonic photonic crystal for manipulating surface plasmon polariton SPP fields has been designed, fabricated, and tested. The band structure of SPP fields inside the plasmonic photonic crystal has been calculated using the plane wave expansion method and validated by full wave numerical simulations. The fabricated device was characterized using our far-field SPP imaging technique. The transmittance of incident SPP waves is about 5% at 1520 n...

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Applied Physics Letters : Generation of polychromatic radially and...

By: T. Grosjean, M. Suarez, and A. Sabac

Description: We propose a fiber-based system aimed at generating radially and azimuthally polarized beams over spectral ranges of several tens of nanometers. The device is either adaptable to polychromatic sources such as supercontinuum fiber lasers or to tunable ones optical parametric oscillator, laser diode, etc. . A preliminary version of the system has been engineered to work in the visible portion of the spectrum. The concept proposed here can be adapted to the in...

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Applied Physics Letters : Enhanced four-wave mixing by atomic cohe...

By: Hai-Hua Wang, Dun-Mao Du, Yun-Fei Fan, Ai-Jun Li, Lei Wang et al

Description: We experimentally demonstrate an enhanced four-wave mixing FWM based on atomic coherence in a Pr3+:Y2SiO5 crystal. By employing coherent population return and fractional stimulated Raman adiabatic passage to prepare maximum atomic coherence in the crystal, an efficient FWM signal can be generated. By measuring the generated FWM signal, the time-dependent atomic coherence is monitored. Such an enhanced FWM in solids may have practical applications in nonlin...

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Applied Physics Letters : Experimental demonstration of a µ = .1 m...

By: Manuel J. Freire, Ricardo Marques, and Lukas Jelinek

Description: In this work a μ =−1 metamaterial MM lens for magnetic resonance imaging MRI is demonstrated. MRI uses surface coils to detect the radio frequency rf energy absorbed and emitted by the nuclear spins in the imaged object. The proposed MM lens manipulates the rf field detected by these surface coils so that the coil sensitivity and spatial localization are substantially improved. Beyond this specific application, we feel that the reported results are th...

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Applied Physics Letters : Directional light extraction from thin-f...

By: K. Bergenek, Ch. Wiesmann, H. Zull, R. Wirth, P. Sundgren et al

Description: We report directional light extraction from AlGaInP thin-film resonant cavity light emitting diodes RCLEDs with shallow photonic crystals PhCs . Diffraction of guided modes into the light extraction cone enhances the light extraction by a factor of 2.6 compared to unstructured RCLEDs, where the farfields still show higher directionality than Lambertian emitters. The external quantum efficiency is 15.5% to air and 26% with encapsulation, respectively. The ...

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Applied Physics Letters : Wave propagation and tunneling through p...

By: I. V. Konoplev, P. Maclnnes, A. W. Cross, A. D. R. Phelps, L. Fisher et al

Description: The phenomenon of tunneling manifests itself in nearly every field of physics. The ability to distinguish a wave tunneling through a barrier from one propagating is important for a number of applications. Here we explore the properties of the wave traveling through the band gap created by a lattice, either as a consequence of tunneling through the barrier or due to the presence of a pass band inside the gap. To observe the pass band for studying tunneling an...

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Applied Physics Letters : Enhanced and partially polarized output ...

By: Kun-Ching Shen, Cheng-Yen Chen, Hung-Lu Chen, Chi-Feng Huang, Yean-Woei Kiang et al

Description: The enhanced and partially polarized output of a green light-emitting diode (LED) , in which its InGaN/GaN quantum well (QW) couples with surface plasmons (SPs) on a surface Ag grating structure, is demonstrated. Compared with a LED sample without flat Ag coating, the total output intensity of an LED of SP-QW coupling can be enhanced by ~59% ( ~ 200 %) when the grating period and groove depth are 500 and 30 nm, respectively. Also, a bottom-emission po...

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Applied Physics Letters : Temperature distribution and modificatio...

By: Masaaki Sakakura, Masahiro Shimizu, Yasuhiko Shimotsuma, Kiyotaka Miura, and Kazuyuki Hirao

Description: Heat accumulation by high repetition rate femtosecond laser irradiation inside glass generates a much larger modification than that by a single pulse. In this study, we determined the temperature distribution due to heat accumulation and the characteristic temperature for heat modification inside a soda lime glass by analyzing the relationship between the radius of modification and glass temperature. The validity of the analysis was confirmed by reproducing ...

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Applied Physics Letters : Restoration of high spatial frequency at...

By: Du Hyun Beak, Jin Woo Yoon, Jae Sung Shin, and Hong Jin Kong

Description: We have found experimentally that it is possible to restore the high spatial frequency of optical images by using stimulated Brillouin scattering (SBS) with a prepulse. The Stokes wave usually has to lose the high spatial frequency because of the necessary energy to generate the acoustic grating. However, this problem has been resolved by using a prepulse method. We have achieved an amplitude increase of ~41% compared to the normal SBS scheme at a spatial ...

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Applied Physics Letters : Depth-resolved holographic optical coher...

By: M. Salvador, J. Prauzner, S. Köber, K. Meerholz, K. Jeong et al

Description: We present coherence-gated holographic imaging using a highly sensitive photorefractive PR polymer composite as the recording medium. Due to the high sensitivity of the composite holographic recording at intensities as low as 5 mW/cm2 allowed for a frame exposure time of only 500 ms. Motivated by regenerative medical applications, we demonstrate optical depth sectioning of a polymer foam for use as a cell culture matrix. An axial resolution of 18 m and a ...

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Applied Physics Letters : Enhanced contrast coherent anti-Stokes R...

By: Michael R. Beversluis and Stephan J. Stranick

Description: We have experimentally demonstrated enhanced image contrast of sample fine structure in a coherent anti-Stokes Raman scattering (CARS) microscope using liquid crystal spatial light modulators as programmable Toraldo-style pupil phase masks. We demonstrated through modeling, implementation, and verification of the focal intensity and phase distributions of the excitation beams the trade-offs between improved image contrast and CARS signal levels.

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Applied Physics Letters : Elliptically polarized terahertz emissio...

By: Yanping Chen, Claude Marceau, Weiwei Liu, Zhen-Dong Sun, Yizhu Zhang et al

Description: Elliptically polarized terahertz emission from a femtosecond laser filament in air in the forward direction was discovered by using a wire grid polarizer and electro-optic sampling technique. The generation mechanism could be through four-wave optical rectification or second-order optical rectification inside the filament zone where the inversion symmetry of air is broken.

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Applied Physics Letters : Ultrafast carrier capturing in GaInP/Er,...

By: Y. Terai, K. Hidaka, K. Fujii, S. Takemoto, M. Tonouchi et al

Description: Carrier capturing in GaInP/Er,O-codoped GaAs (GaAs:Er,O) /GaInP laser diodes (LDs) was investigated by means of the threshold current density (Jth) of laser emission. The Er-doped LDs showed laser emission of the GaAs band edge at room temperature, and its Jth increases with the Er flow rate during the growth. In the dependence of Jth on reciprocal cavity length, the effective gain factor of the LDs decreased by the codoping of Er and O. These results r...

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Applied Physics Letters : Underwater microdischarge in arranged mi...

By: Osamu Sakai, Masaru Kimura, Tatsuru Shirafuji, and Kunihide Tachibana

Description: Pulsed microdischarge was generated in microbubbles produced by electrolysis in an electrolyte solution without external gas feed by using a fabric-type electrode. The electrode structure not only allowed low-voltage ignition of the atmospheric-pressure discharge in hydrogen or oxygen containing microbubbles but also worked effectively in producing and holding the bubbles on its surface. The generation of reactive species was verified by optical emissions fr...

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