Topic
Brillouin zone
About: Brillouin zone is a research topic. Over the lifetime, 13849 publications have been published within this topic receiving 383077 citations.
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TL;DR: In this article, the phonon spectra, distortion mechanisms, and thermoelastic properties of cubic perovskite structure were investigated as a function of pressure using a lattice dynamic approach.
Abstract: The phonon spectra, distortion mechanisms, and thermoelastic properties of CaSiO3and MgSiO3 in the cubic perovskite structure are investigated as a function of pressure using a lattice dynamic approach. The bonding forces are derived from a parameter-free rigid-ion electron-gas formulation. At low pressures, CaSiO3 is found to be dynamically stable in the cubic perovskite structure; however, the phonon spectrum exhibits soft modes at the Brillouin zone boundary which ultimately result in a dynamic instability of the lattice near 80 GPa. The computed phonon spectrum of cubic MgSiO3 perovskite exhibits complex frequencies along parts of the zone boundary at all densities investigated. These vibrational instabilities include coupled octahedral rotations which produce the observed distorted structure of MgSiO3 perovskite. The measured bulk modulus of MgSiO3 perovskite compares well with our calculated value for the cubic structure.
76 citations
TL;DR: A time-domain distributed temperature sensing based on birefringence effect on transient Brillouin grating in a polarization-maintaining photonic crystal fiber (PM-PCF), which uses two short pump pulses to excite a TBG and a long probe pulse to map the transient Brillouchi grating spectrum associated with the bireFringence.
Abstract: We demonstrate a time-domain distributed temperature sensing based on birefringence effect on transient Brillouin grating (TBG) in a polarization-maintaining photonic crystal fiber (PM-PCF), which uses two short pump pulses (2 ns) to excite a TBG and a long probe pulse (6 ns) to map the transient Brillouin grating spectrum (TBGS) associated with the birefringence. The 2 ns pump pulses defines a spatial resolution of 20 cm and a temperature measurement range of a few hundred degrees Celsius, and the long probe pulse provides a narrow TBGS with a temperature resolution of 0.07°C.
76 citations
TL;DR: In this paper, a Brillouin technique is proposed for determining the acoustic and opto-acoustic properties of thin polymers at hypersonic frequencies, which is especially suitable for studying acoustic dispersion behavior at high frequencies.
Abstract: Within this paper we propose a versatile Brillouin technique which allows an easy determination of acoustic and opto-acoustic properties of thin films. This new technique is especially suitable for studying acoustic dispersion behaviour at hypersonic frequencies. Typical applications in the field of polymers have been used to demonstrate the efficiency of the proposed scattering technique.
76 citations
TL;DR: Brillouin light scattering is utilized to investigate the magnetic properties of the hexagonal-close-packed as well as the body- and face-centered cubic phases of elemental cobalt stabilized as thin epilayers and the implications towards the understanding of magnetic property of itinerant ferromagnets are discussed.
Abstract: We utilize Brillouin light scattering to investigate the magnetic properties of the hexagonal-close-packed as well as the body- and face-centered cubic phases of elemental cobalt stabilized as thin epilayers. Expressions for the dependence of the surface and bulk magnons on applied magnetic field and in-plane propagation direction yield the exchange stiffness constant D, saturation magnetization M, and magnetic anisotropy fields of the cobalt atoms synthesized in these distinct crystal structures. Estimates of D and M are also calculated from the electronic band structure for the different crystalline phases. Satisfactory agreement is found between theory and experiment. The implications of these results towards our understanding of magnetic properties of itinerant ferromagnets are discussed. \textcopyright{} 1996 The American Physical Society.
76 citations
TL;DR: Through this analysis, it is determined numerically that the bandwidth of the Brillouin backscattered light becomes wider, and thus the measurement accuracy in determining the peak-power frequency degrades in approximately inverse proportion to the launched pulse width.
Abstract: We theoretically analyze the relation between the pulse width of light launched into an optical fiber and the resultant power spectrum of spontaneous Brillouin backscattered light. Through this analysis, we determine numerically that the bandwidth of the Brillouin backscattered light becomes wider, and thus the measurement accuracy in determining the peak-power frequency degrades in approximately inverse proportion to the launched pulse width. Experimental results with various pulse widths are in good agreement with the derived theoretical results.
76 citations