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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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Journal of Applied Physics : Study of laser excited vibration of s...

By: Yaqin Song, Bernard Cretin, D. M. Todorovic, and Pascal Vairac

Description: In this paper an interferometric setup called “thermoelastic microscopy” has been used to measure the vibration response of the semiconductor cantilevers under modulated laser thermal source. The small vibration amplitude has been detected well below 10 pm magnitude in accurate adjustment conditions. The results showed that experimental responses have a good agreement with the theoretical ones. Also from the analysis we could conclude that the signal amplitu...

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Applied Physics Letters : Effects of disorder and scaling of optic...

By: K. R. Mavani, M. Nagai, D. S. Rana, H. Yada, I. Kawayama et al

Description: We have explored the low energy charge dynamics of charge-ordered Nd0.5Ca0.5MnO3 and Ba-doped Nd0.5Ca0.48Ba0.02MnO3 manganite thin films by recording the complex optical spectra using terahertz time-domain spectroscopy. The extracted frequency- and temperature-dependent optical conductivity (σ) and dielectric constant (ε1) show distinct features at Néel’s ordering and the charge-ordering temperatures (TN and TCO) . We found that the Ba-doping induced cation...

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Physics of Plasmas : Physics of collisionless phase mixing

By: D. Tsiklauri and T. Haruki

Description: Previous studies of phase mixing of ion cyclotron (IC), Alfvénic, waves in the collisionless regime have established the generation of parallel electric field and hence acceleration of electrons in the regions of transverse density inhomogeneity. However, outstanding issues were left open. Here we use the 2.5 D, relativistic, fully electromagnetic particle-in-cell code and an analytic magnetohydrodynamic (MHD) formulation, to establish the following points: ...

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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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Journal of Applied Physics : Ion transport in polyacetylene ionomers

By: Fuding Lin, Yongjun Wang, and Mark Lonergan

Description: Ion transport in cationically and anionically functionalized polyacetylene ionomers, PAC and PAA, respectively, was investigated by analyzing the impedance responses of thin film Au∣ionomer∣Au sandwich configurations. Samples were measured over a frequency range of 10−2–106 Hz and a temperature range of 298–398 K. Electrode polarization at low frequencies and dispersion due to ion hopping at higher frequencies were observed. The impedance data were analyzed ...

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Chaos : Response to Comment on 'Synchronization of chaotic systems...

By: Tingwen Huang, Chuandong Li, and Xinzhi Liu

Description:

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Applied Physics Letters : Uniform InGaAs quantum dot arrays fabric...

By: X. Qian, J. Li, D. Wasserman, and W. D. Goodhue

Description: We demonstrate the fabrication of optically active uniform InGaAs quantum dot arrays by combining nanosphere lithography and bromine ion-beam-assisted etching on a single InGaAs/ GaAs quantum well. A wide range of lateral dot sizes was achieved from an oxygen plasma nanosphere resizing process. The increased lateral confinement of carriers in the dots results in low temperature photoluminescence blueshifts from 0.5 to 11 meV. Additional quantization was achi...

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Chaos : Complete periodic synchronization in coupled systems

By: Wei Zou and Meng Zhan

Description: Recently, complete chaotic synchronization in coupled systems has been well studied. In this paper, we study complete synchronization in coupled periodic oscillators with diffusive and gradient couplings. Eight typical types of critical curve for the transverse Lyapunov exponent of standard mode, which give rise to different synchronization-desynchronization patterns, are classified. All possible desynchronous behaviors including steady state, periodic state...

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Biblioteca Hispanica : Discourse in Central University by Don Bern...

By: Bernardino Gallego and Saceda
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The Journal of Chemical Physics : Magnetic exchange couplings from...

By: Juan E. Peralta and Veronica Barone

Description: We propose a method for the evaluation of magnetic exchange couplings based on noncollinear spin density functional calculations. The method employs the second derivative of the total Kohn–Sham energy of a single reference state, in contrast to approximations based on Kohn–Sham total energy differences. The advantage of our approach is twofold: It provides a physically motivated picture of the transition from a low-spin to a high-spin state, and it utilizes ...

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Journal of Applied Physics : Transitions of epitaxially lifted-off...

By: C. M. N. Mateo, J. J. Ibañez, J. G. Fernando, J. C. Garcia, K. Omambac et al

Description: Low temperature photoluminescence and reflectance measurements on epitaxially lifted-off (ELO) bulk GaAs and GaAs/AlGaAs multiple quantum wells (MQWs) bonded to Si and MgO substrates are reported. Photoluminescence measurements indicate no strain at room temperature for the ELO bulk GaAs film but show biaxial strain at 10 K. Si-bonded films undergo tensile strain, while films with MgO host substrates experience compressive strain. Reflectance measurements at...

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Physics of Fluids : Experimental investigation of turbulent diffus...

By: Balaji Gopalan, Edwin Malkiel, and Joseph Katz

Description: High-speed inline digital holographic cinematography is used for studying turbulent diffusion of slightly buoyant 0.5–1.2 mm diameter diesel droplets and 50 μm diameter neutral density particles. Experiments are performed in a 50×50×70 mm3 sample volume in a controlled, nearly isotropic turbulence facility, which is characterized by two dimensional particle image velocimetry. An automated tracking program has been used for measuring velocity time history of ...

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Applied Physics Letters : Ferromagnetic structurally disordered Zn...

By: K. Potzger, Shengqiang Zhou, Qingyu Xu, A. Shalimov, R. Groetzschel et al

Description: We present superparamagnetic clusters of structurally highly disordered Co–Zn–O created by high fluence Co ion implantation into ZnO (0001) single crystals at low temperatures. This secondary phase cannot be detected by common x-ray diffraction but is observed by high-resolution transmission electron microscopy. In contrast to many other secondary phases in a ZnO matrix, it induces low-field anomalous Hall effect and is thus a candidate for magnetoelectronics applications.

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Physics of Fluids : Viscous jet drawing air into a bath

By: Etienne Reyssat, Elise Lorenceau, Frédéric Restagno, and David Quéré

Description:

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Journal of Applied Physics : Charge dynamics in ionic polymer meta...

By: Maurizio Porfiri

Description: In this paper, we study the charge dynamics in ionic polymer metal composites (IPMCs) in response to a voltage difference applied across their electrodes. We use the Poisson–Nernst–Planck equations to model the time evolution of the electric potential and the concentration of mobile counterions. We present an analytical solution of the nonlinear initial-boundary value problem by using matched asymptotic expansions. We determine the charge and electric potent...

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Review of Scientific Instruments : Bubble velocity, diameter, and ...

By: Ho-Joon Lim, Kuang-An Chang, Chin B. Su, and Chi-Yueh Chen

Description: A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the unde...

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Review of Scientific Instruments : Transferring cold atoms in doub...

By: Junmin Wang, Jing Wang, Shubin Yan, Tao Geng, and Tiancai Zhang

Description: A novel scheme of transferring cold atoms in a double magneto-optical trap (MOT) system has been experimentally demonstrated. Cold cesium atoms trapped in a vapor-cell MOT are efficiently transferred to an ultrahigh-vacuum (UHV) MOT by a continuous-wave divergent Gaussian transfer laser beam. When large red detuning and moderate intensity are adopted for the transfer laser beam, enhancement of the recapturing of atoms in the UHV MOT is clearly observed. Usin...

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Review of Scientific Instruments : Polarimetric interferometer for...

By: S. Xu, K. Ouedraogo, L. Chassagne, S. Topçu, P. Juncar et al

Description: We propose and demonstrate a displacement control method at the subnanometric scale based on a Michelson interferometer combined with a polarimeter and a phase-locked loop electronic board. Step by step displacements with a step value of 5 nm are presented. A repeatability of 0.47 nm is obtained from back and forth displacements over 1 μm range. We show that a residual ellipticity of less than 10° on the polarization state leads to a positioning error of les...

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Review of Scientific Instruments : High-resolution Rydberg tagging...

By: Brant Jones, Jingang Zhou, Lei Yang, and C. Y. Ng

Description: By coupling a comprehensive tunable vacuum ultraviolet (VUV) laser system to a velocity-mapped ion imaging apparatus, we show that high-resolution high-n Rydberg tagging time-of-flight (TOF) measurements of nascent atomic photofragments formed by laser photodissociation can be made using single-photon VUV laser photoexcitation. To illustrate this single-photon Rydberg tagging TOF method, we present here the results of the VUV laser high-n Rydberg tagging TOF...

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