Summary form only given. The work reports a new high responsivity high sensitivity, high frequency and low voltage photodetector capable of operating at 850 nm and lower wavelengths at multi-GHz frequencies, while pro...
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Summary form only given. The work reports a new high responsivity high sensitivity, high frequency and low voltage photodetector capable of operating at 850 nm and lower wavelengths at multi-GHz frequencies, while providing compatibility with silicon system-on-chip technology. By decoupling the carrier generation process from the carrier collection process, silicon can provide performance characteristics that are either comparable of superior to that achieved from III-V semiconductors. This decoupling is achieved using deep-trench technology based lateral p/sup ++/-polysilicon doped and n/sup ++/-doped junctions that allow for short carrier collection distances while allowing for large absorption depths. Use of poly-silicon-based junctions in silicon allows for low darkcurrent and nearly ideal diodes. Small junction separations and low doping allow low bias and efficient separation of carriers.
In this paper, the technique of model reference robust control (MRRC) is applied to a passive line-of-sight (LOS) stabilization system. The system uses a flywheel as a spinning mass gyroscope to stabilize a two gimbal...
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In this paper, the technique of model reference robust control (MRRC) is applied to a passive line-of-sight (LOS) stabilization system. The system uses a flywheel as a spinning mass gyroscope to stabilize a two gimbal system against base motion. Due to the gimbal geometry, unwanted dynamic coupling exists in the LOS system. The system is treated as a two input - two output system, and it is then decoupled and controlled using only input/output measurements rather than state feedback. The technique used in this paper for decoupling and control of the LOS system is MRRC which is an extension of model reference control to nonlinear MIMO systems. The technique utilizes bounds of plant parameter uncertainties via controller parameter uncertainties and also input disturbances bounds. Specifically, dynamics of the passive line-of-sight stabilization system are described, followed by a perfect knowledge (MRC) control design and then a nonlinear robust control design.
Sub-two-cycle optical pulses (5 fs) with spectra extending over more than one octave are generated directly from a Kerr-lens modelocked (KLM) Ti:sapphire laser. Applications of this broadband source in optical coheren...
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Sub-two-cycle optical pulses (5 fs) with spectra extending over more than one octave are generated directly from a Kerr-lens modelocked (KLM) Ti:sapphire laser. Applications of this broadband source in optical coherence tomography and phase sensitive nonlinear optics are demonstrated.
We report results of very sensitive electron spin resonance (ESR) and electrical measurements made on MOSFETs subjected to medium energy proton bombardment. We observe that the measured defect density levels are simil...
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We report results of very sensitive electron spin resonance (ESR) and electrical measurements made on MOSFETs subjected to medium energy proton bombardment. We observe that the measured defect density levels are similar for both the ESR measurements and electrical measurements. The density of defects is observed to be larger for proton bombarded devices compared to devices irradiated with much larger doses of /sup 60/Co gamma rays. Initial ESR and electrical measurements were made on-site soon after bombardment in the cyclotron.
Summary form only given. Soliton interactions are universal, displaying features common to all solitons, in spite of the diversity of the physical systems in which solitons are found. The reason for this universality ...
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Summary form only given. Soliton interactions are universal, displaying features common to all solitons, in spite of the diversity of the physical systems in which solitons are found. The reason for this universality is the fact that solitons can be viewed as modes of their own induced waveguide. The simplest case arises when the self-induced waveguide has only one mode populated, in which case the soliton is a "scalar soliton". In this vein, collisions of single-mode solitons can be viewed intuitively as interactions between guided modes of adjacent waveguides. In this case, the interaction outcome is determined by the relation between the collision angle and the (complementary) critical angle for total internal reflection in each waveguide, /spl theta//sub c/. Experimentally, collisions between scalar solitons were studied in detail, demonstrating fully-elastic collisions between Kerr solitons, almost-elastic collisions between solitons in saturable nonlinearities interacting at angles above /spl theta//sub c/ and inelastic collisions that yield fusion, fission, annihilation, and spiraling.
It is shown that the Mel’nikov-Meshkov formalism for bridging the very low damping (VLD) and intermediate-to-high damping (IHD) Kramers escape rates as a function of the dissipation parameter for mechanical particles...
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It is shown that the Mel’nikov-Meshkov formalism for bridging the very low damping (VLD) and intermediate-to-high damping (IHD) Kramers escape rates as a function of the dissipation parameter for mechanical particles may be extended to the rotational Brownian motion of magnetic dipole moments of single-domain ferromagnetic particles in nonaxially symmetric potentials of the magnetocrystalline anisotropy so that both regimes of damping occur. The procedure is illustrated by considering the particular nonaxially symmetric problem of superparamagnetic particles possessing uniaxial anisotropy subject to an external uniform field applied at an angle to the easy axis of magnetization. Here the Mel’nikov-Meshkov treatment is found to be in good agreement with an exact calculation of the smallest eigenvalue of Brown’s Fokker-Planck equation, provided the external field is large enough to ensure significant departure from axial symmetry, so that the VLD and IHD formulas for escape rates of magnetic dipoles for nonaxially symmetric potentials are valid.
KTiOPO/sub 4/ (KTP) crystals doped with Nb (Nb:KTP) can not only largely blue-shift the cut-off wavelength for the type II second harmonic generation (SHG) phase matching of KTP crystals, but can also change the optim...
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KTiOPO/sub 4/ (KTP) crystals doped with Nb (Nb:KTP) can not only largely blue-shift the cut-off wavelength for the type II second harmonic generation (SHG) phase matching of KTP crystals, but can also change the optimum phase matching angle of Nd:YAG 1.0642 /spl mu/m laser which has a noncritical phase matching direction.
作者：
M.R. BlackD.A. BroidoG. ChenS.B. CroninG. DresselhausM.S. DresselhausT. KogaY.-M. LinG.D. MahanO. RabinT.L. ReineckeRama Venkatasubramanian(1)
Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts (123)
Department of Physics Boston College Chestnut Hill Massachusetts (203)
Mechanical and Aerospace Engineering Department University of California Los Angeles California (1)
Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts (1)
Francis Bitter Magnet Laboratory Massachusetts Institute of Technology Cambridge Massachusetts (1)
Department of Physics and Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts (1)
Department of Applied Physics Harvard University Cambridge Massachusetts (157)
Solid State Division Oak Ridge National Laboratory Oak Ridge Tennessee (1)
Department of Chemistry Massachusetts Institute of Technology Cambridge Massachusetts (123)
Naval Research Laboratory Washington D.C. (175)
Research Triangle Institute Research Triangle Park North Carolina
Superconducting circuits with Josephson tunnel junctions are interesting systems for research on quantum-mechanical behavior of macroscopic degrees of freedom. A particular realization is a small superconducting loop ...
Superconducting circuits with Josephson tunnel junctions are interesting systems for research on quantum-mechanical behavior of macroscopic degrees of freedom. A particular realization is a small superconducting loop containing three Josephson junctions. Close to magnetic frustration 1/2, the physics of this system corresponds to a double well, whose minima correspond to persistent currents of opposite sign. We present DC measurements of the flux indicating a smooth transition close to the degeneracy point even at very low temperatures. Furthermore, microwave-spectroscopy experiments allow for the excitation to the next excited state. The dependence of the energy of the resonance on the applied flux clearly indicates the nature of these states as tunneling-splitted superpositions of flux states. We theoretically analyze the system using a generalized master-equation formulation of the spin-boson model. We address the nature of the measuring process by a switching DC SQUID and the possible interpretation of the spectroscopy data in terms of quantum coherence. We discuss these aspects in the context of further applications as a quantum bit.
Signals from 12 soprano and mezzo-soprano singers are analyzed with the modal distribution, a high-resolution time-frequency analysis method, to obtain measures of instantaneous amplitude and frequency of the signals...
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