RF-MEMS for basestations

  • Fischer G.

Talk: 1) Introduction 2) Frequency agile radio versus SDR 3) Multiband power amplifiers 4) Summary

AlGaN/GaN HEMTs Grown by Molecular Beam Epitaxy on Sapphire, SiC, and HVPE GaN Templates

  • Baldwin K.
  • D.V. Lang
  • Hsu J.
  • Manfra M.
  • Pfeiffer L.
  • R.J. Molnar
  • S.N.G. Chu
  • Weimann N.
  • West K.

Molecular Beam Eiptaxy of GaN and related alloys is becoming a rival to the more established Metalorganic Vapor Phase Epitaxy. Excellent control of impurity, interface abruptness, and in-situ monitoring of the growth are driving the increase in quality of MBE epilayers. We have developed nucleation schemes with plasma-assisted MBE on ...

Dynamic Configuration of Mobile Devices for Wireless Internet Access

  • Laporta T.
  • Ramjee R.
  • Salgarelli L.
  • Thuel S.

This chapter provides a taxonomy of dynamic configuration solutions for mobile devices and focuses on the study of two proposals which use the home agent to mediate a mobile device's access to DHCP, namely, Transient Tunneling and DHCP proxy [8,12,13]. In Transient Tunneling, a home agent is used to temporarily ...

Congestion Control Policies for IP-Based CDMA Radio Access Networks

  • Kasera S.
  • Ramjee R.
  • Thuel S.
  • Wang X.

In this paper we propose and evaluate three congestion control mechanisms, admission control, diversity control, and router control, to maximize network capacity while maintaining good voice quality. We first propose two new enhancements to CDMA call admission control so that a unified view of both IP RAN and air interface ...

Enhanced and Suppressed Birefringence in Fiber Bragg Gratings

  • L.E. Pipe
  • S. Pereira
  • Slusher R.

We demonstrate theoretically and experimentally that the two orthogonal polarizations of light see an unequal index constrast in a UV induced fiber Bragg grating. We find that in a Bragg grating the phase velocity mismatch is a function of detuning, and hence we can introduce an effective birefringence. The description ...

Supercontinuum Quantum Cascade Laser for Subpicosecond Mid-IR Pulse Generation

  • Capasso F.
  • Cho A.
  • Gmachl C.
  • Hc L.
  • Hwang H.
  • Sivco D.
  • Soibel A.

A supercontinuum quantum cascade (QC) laser with flat optical gain from 6.7 to 7.4mum wavelength was designed and fabricated to provide a wavelength independent threshold current.

A 2 Rebit Gate Universal for Quantum Computing

  • Grover L.
  • T. Rudolph

We show, within the circuit model, how any quantum computation can be efficiently performed using states with only real amplitudes (a result known within the Quantum Turing Machine model). This allows us to identify a 2-qubit (in fact 2-rebit) gate which is universal for quantum computing, although it cannot be ...

Large Synoptic Survey Telescope: Overview

  • Tyson J.

A large wide-field telescope and camera with optical throughput over 200 m sup 2 deg sup 2 -- a factor of 50 beyond what we currently have -- would enable the detection of faint moving or bursting optical objects: from Earth threatening asteroids to energetic events at the edge of ...

Vapor Sensing with alpha, omega-Dihexylquarterthiophene Field-Effect Transistors: The Role of Grain Boundaries

  • A. Dodabalapur
  • A. Gelperin
  • Katz H.
  • Lovinger A.
  • T. Someya

We have investigated the channel-length dependence of responses to a vapor analyte with a series of alpha, omega-dihexylquarterthiophene (DHalpha4T) field-effect transistors (FETs). Single-crystalline DHalpha4T devices deposited by vacuum sublimation at substrate temperatures of 70 degC are compared with polycrystalline DHalpha4T films deposited at room temperature. By changing the length of ...

A Microscope for Imaging, Spectroscopy, and Lithography at the Nanometer Scale: Combination ofa Two-Photon Laser Scanning Microscope and an Atomic Force Microscope

  • Chaban E.
  • F.F. Schey
  • Hsu J.
  • Matthews M.

We designed and built a unique instrument that combines a two-photon laser scanning microscope (LSM) with an inverted atomic force microscope (AFM). Local photoluminescence (PL) spectroscopy and three-dimensional lithography are demonstrated using the two-photon LSM. High spatial resolution topographic images from the AFM can be recorded simultaneously with the PL ...

Submicron AlGaN/GaN HEMTs with very high drain current density grown by plasma Assisted MBE on 6H-SiC

  • Manfra M.
  • S. Chakraborty
  • Tennant D.
  • Weimann N.

High Electron Mobility Transistors (HEMTs) were fabricated from AlGaN/GaN layers grown by plasma-assisted Molecular Beam Epitaxy on semi-insulating 6H-SiC substrates. This is the first report of high-power submicron AlGaN/GaN HEMTs grown by plasma-assisted MBE on semi-insulating 6H-SiC substrates, and the highest drain current density in any AlGaN/GaN HEMT structure delivering ...

Evidence of Landau Levels and Interactions in Low-Lying Excitations of Composite Fermions at 1/3 <= v <= 2/5

  • Dennis B.
  • I. Dujovne
  • M. Kang
  • Pfeiffer L.
  • Pinczuk A.
  • West K.

Excitation modes in the range 2/5 >= v >= 1/3 of the fractional quantum Hall regime are observed by resonant inelastic light scattering. Spectra of spin reversed excitations suggest a structure of lowest spin-split Landau levels of composite fermions that is similar to that of electrons. Spin-flip energies determined from ...

Inelastic Light-Scattering and Photoluminescence from Extremely High-Mobility Very Dilute Two-Dimensional Hole Gases

  • Dennis B.
  • Pfeiffer L.
  • Pinczuk A.
  • Plaut A.
  • West K.

We have observed charged excitons by optical emission and intersubband transitions by inelastic light-scattering in two-dimensional very dilute hole gases with As-grown hole densities down to below p = 6.5x10 sup 9 cm sup -2. The hole mobility reaches 2.1x10 sup 6 cm sup 2/Vs at 0.3 Kelvin.

Quantum Cascade Lasers with Heterogeneous, Stacked Cascades: Sum-Frequency and Second Harmonic Generation

  • Capasso F.
  • Cho A.
  • Colombelli R.
  • Gmachl C.
  • N. Owschimikow
  • Sivco D.

Quantum cascade (QC) lasers have recently been demonstrated with stacked, interdigitated or collaborative cascades. Different active regions, in all cases of the "three-well vertical transition" type and designed at different emission wavelengths, were stacked -- with matching injector regions -- and inserted into one waveguide core. This approach is attractive ...

Mid-IR Electroluminescence in Quantum Cascade Structures with GaInAs/InP Active Region

  • Capasso F.
  • Chen J.
  • Cho A.
  • Gmachl C.
  • Peabody M.
  • Sivco D.
  • Troccoli M.

Quantum Cascade (QC) lasers are based on inter-subband transitions in the conduction band. This characteristic gives the flexibility to design the active region specifically to meet the user requirements, almost independently of the material chosen for its realization. So far, laser action has been reported in a number of different ...

Weak Lensing Discovery and Tomography of a Cluster at Z = 0.68

  • I.P. Dell'Antonio
  • J.G. Cohen
  • Margoniner V.
  • Tyson J.
  • Wittman D.

We report the discovery, spectrographic confirmation, and weak lensing tomography of a massive cluster of galaxies at z = 0.68. The first shear-selected cluster from the Deep Lens Survey, a deep optical imaging survey of 28 deg sup 2, it dominates the weak lensing mass map of its 40' field. ...

OSNR Margin Assessment for Optical Transmissions in the Nonlinear Regime with Forward Error Correction

  • Chandrasekhar S.
  • Gnauck A.
  • Liu X.
  • Wei X.

We study numerically and experimentally the OSNR margin of high-speed optical transmission systems in the nonlinear regime at FEC thresholds. It is found that the OSNR margin can be significatnly larger than the Q margin, in contrast to ideal linear case. As a result, the FEC coding gains for transmissions ...

Polarization Dependent Parametric Gain in Amplifiers with Orthogonally Multiplexed Optical Pumps

  • C. Headley
  • C.G. Jorgensen
  • Jopson R.
  • K. Brar
  • Mckinstrie C.
  • Radic S.

We show that the orthogonal pump configuration does not guarantee the polarization insensitive operation of two-pump parametric amplifiers. Experimental observations are made with various lengths of highly nonlinear optical fiber to demonstrate the polarization dependence of the parametric gain.

Alternating Subspace-Spanning Resampling to Accelerate Markov Chain Monte Carlo Simulation

  • Liu C.

This paper provides a simple method to accelerate MCMC sampling algorithms, such as the data augmentation and the Gibbs sampler, via alternating subspace-spanning resampling (ASSR). The ASSR algorithm often shares the simplicity of its parent sampler but has dramatically improved efficiency. The methodology is illustrated with Bayesian estimation for analysis ...

Telecommunications Industry's View of Profitable

  • Furman D.
  • Wang Q.

This paper presents an analytical model that complements empirical studies for determining the profitability of a segment in the telecommunications industry. By considering impacts of technology innovation, which is a non-incremental force that drives market development, and simulating carrier's optimal decision-making, we show that in order for the segment to ...