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Matthew R Pufall - One of the best experts on this subject based on the ideXlab platform.

  • time Domain Measurement of phase noise in a spin torque oscillator
    Applied Physics Letters, 2009
    Co-Authors: Mark W Keller, Thomas J Silva, William H Rippard, Matthew R Pufall
    Abstract:

    We measure oscillator phase from the zero crossings of the voltage versus time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency f as 1/f2, consistent with frequency fluctuations driven by a thermal source. The linewidth implied by phase noise alone is about 70% of that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth.

  • time Domain Measurement of phase noise in a spin torque oscillator
    arXiv: Mesoscale and Nanoscale Physics, 2009
    Co-Authors: Mark W Keller, Thomas J Silva, William H Rippard, Anthony B Kos, Matthew R Pufall
    Abstract:

    We measure oscillator phase from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency $f$ as $1/f^2$, consistent with frequency fluctuations driven by a thermal source. The linewidth implied by phase noise alone is about 70 % of that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth.

Paul L. Mceuen - One of the best experts on this subject based on the ideXlab platform.

  • Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube
    Nature Nanotechnology, 2008
    Co-Authors: Zhaohui Zhong, Nathaniel M. Gabor, Jay E. Sharping, Alexander L. Gaeta, Paul L. Mceuen
    Abstract:

    Understanding the physics of low-dimensional systems and the operation of next-generation electronics will depend on our ability to measure the electrical properties of nanomaterials at terahertz frequencies (∼100 GHz to 10 THz). Single-walled carbon nanotubes are prototypical one-dimensional nanomaterials because of their unique band structure^ 1 , 2 and long carrier mean free path^ 3 , 4 , 5 . Although nanotube transistors have been studied at microwave frequencies (100 MHz to 50 GHz)^ 6 , 7 , 8 , 9 , 10 , 11 , no techniques currently exist to probe their terahertz response^ 12 . Here, we describe the first terahertz electrical Measurements of single-walled carbon nanotube transistors performed in the time Domain. We observe a ballistic electron resonance that corresponds to the round-trip transit of an electron along the nanotube with a picosecond-scale period. The electron velocity is found to be constant and equal to the Fermi velocity, showing that the high-frequency electron response is dominated by single-particle excitations rather than collective plasmon modes. These results demonstrate a powerful new tool for directly probing picosecond electron motion in nanostructures.

  • Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube
    Nature nanotechnology, 2008
    Co-Authors: Zhaohui Zhong, Nathaniel M. Gabor, Jay E. Sharping, Alexander L. Gaeta, Paul L. Mceuen
    Abstract:

    Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube

Mark W Keller - One of the best experts on this subject based on the ideXlab platform.

  • time Domain Measurement of phase noise in a spin torque oscillator
    Applied Physics Letters, 2009
    Co-Authors: Mark W Keller, Thomas J Silva, William H Rippard, Matthew R Pufall
    Abstract:

    We measure oscillator phase from the zero crossings of the voltage versus time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency f as 1/f2, consistent with frequency fluctuations driven by a thermal source. The linewidth implied by phase noise alone is about 70% of that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth.

  • time Domain Measurement of phase noise in a spin torque oscillator
    arXiv: Mesoscale and Nanoscale Physics, 2009
    Co-Authors: Mark W Keller, Thomas J Silva, William H Rippard, Anthony B Kos, Matthew R Pufall
    Abstract:

    We measure oscillator phase from the zero crossings of the voltage vs. time waveform of a spin torque nanocontact oscillating in a vortex mode. The power spectrum of the phase noise varies with Fourier frequency $f$ as $1/f^2$, consistent with frequency fluctuations driven by a thermal source. The linewidth implied by phase noise alone is about 70 % of that measured using a spectrum analyzer. A phase-locked loop reduces the phase noise for frequencies within its 3 MHz bandwidth.

Zhaohui Zhong - One of the best experts on this subject based on the ideXlab platform.

  • Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube
    Nature Nanotechnology, 2008
    Co-Authors: Zhaohui Zhong, Nathaniel M. Gabor, Jay E. Sharping, Alexander L. Gaeta, Paul L. Mceuen
    Abstract:

    Understanding the physics of low-dimensional systems and the operation of next-generation electronics will depend on our ability to measure the electrical properties of nanomaterials at terahertz frequencies (∼100 GHz to 10 THz). Single-walled carbon nanotubes are prototypical one-dimensional nanomaterials because of their unique band structure^ 1 , 2 and long carrier mean free path^ 3 , 4 , 5 . Although nanotube transistors have been studied at microwave frequencies (100 MHz to 50 GHz)^ 6 , 7 , 8 , 9 , 10 , 11 , no techniques currently exist to probe their terahertz response^ 12 . Here, we describe the first terahertz electrical Measurements of single-walled carbon nanotube transistors performed in the time Domain. We observe a ballistic electron resonance that corresponds to the round-trip transit of an electron along the nanotube with a picosecond-scale period. The electron velocity is found to be constant and equal to the Fermi velocity, showing that the high-frequency electron response is dominated by single-particle excitations rather than collective plasmon modes. These results demonstrate a powerful new tool for directly probing picosecond electron motion in nanostructures.

  • Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube
    Nature nanotechnology, 2008
    Co-Authors: Zhaohui Zhong, Nathaniel M. Gabor, Jay E. Sharping, Alexander L. Gaeta, Paul L. Mceuen
    Abstract:

    Terahertz time-Domain Measurement of ballistic electron resonance in a single-walled carbon nanotube

Waclaw Urbanczyk - One of the best experts on this subject based on the ideXlab platform.

  • Spectral-Domain Measurement of strain sensitivity of a two-mode birefringent holey fiber
    18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2012
    Co-Authors: Petr Hlubina, Mariusz Makara, Krzysztof Poturaj, Tadeusz Martynkien, Jacek Olszewski, Pawel Mergo, Waclaw Urbanczyk
    Abstract:

    In this paper, the strain sensitivity of a two-mode birefringent holey fiber is measured in the spectral Domain. In a simple experimental setup comprising a broadband source, a polarizer, a two-mode birefringent holey fiber under varied elongations, an analyzer and a compact spectrometer, the spectral interferograms are resolved. These are characterized by a specific wavelength, the equalization wavelength, at which spectral interference fringes have the highest visibility (the largest period) due to the zero group optical path difference between the fundamental, the LP01 mode and the higher-order, the LP11 mode. The spectral interferograms with the equalization wavelength are processed by a new method to retrieve the phase as a function of the wavelength. From the retrieved phase functions corresponding to different elongations of a two-mode birefringent holey fiber under test, the spectral strain sensitivity is obtained. Using this approach, the intermodal spectral strain sensitivity was measured for two orthogonal (x and y) polarizations.

  • Spectral-Domain Measurement of Strain Sensitivity of a Two-Mode Birefringent Side-Hole Fiber
    Sensors, 2012
    Co-Authors: Petr Hlubina, Mariusz Makara, Krzysztof Poturaj, Tadeusz Martynkien, Jacek Olszewski, Pawel Mergo, Waclaw Urbanczyk
    Abstract:

    The strain sensitivity of a two-mode birefringent side-hole fiber is measured in the spectral Domain. In a simple experimental setup comprising a broadband source, a polarizer, a two-mode birefringent side-hole fiber under varied elongations, an analyzer and a compact spectrometer, the spectral interferograms are resolved. These are characterized by the equalization wavelength at which spectral interference fringes have the highest visibility (the largest period) due to the zero group optical path difference between the fundamental, the LP01 mode and the higher-order, the LP11 mode. The spectral interferograms with the equalization wavelength are processed to retrieve the phase as a function of the wavelength. From the retrieved phase functions corresponding to different elongations of a two-mode birefringent side-hole fiber under test, the spectral strain sensitivity is obtained. Using this approach, the intermodal spectral strain sensitivity was measured for both x and y polarizations. Moreover, the spectral polarimetric sensitivity to strain was measured for the fundamental mode when a birefringent delay line was used in tandem with the fiber. Its spectral dependence was also compared with that obtained from a shift of the spectral interferograms not including the equalization wavelength, and good agreement was confirmed.