Showing papers on "Brillouin scattering published in 1990"
TL;DR: In this paper, the power limitations of light-wave systems were analyzed as a function of a number of wavelength-multiplexed channels and methods for scaling these results with changes in system parameters were presented.
Abstract: Optical nonlinearities in the context of lightwave systems limitations are described. The nature and severity of system degradation due to stimulated Raman scattering, carrier-induced phase noise, stimulated Brillouin scattering, and four-photon mixing are discussed. The system power limitations are plotted as a function of a number of wavelength-multiplexed channels. Methods for scaling these results with changes in system parameters are presented. >
787 citations
TL;DR: Temperature distribution in silica single-mode optical fibers, from -30 to +60 degrees C, is successfully measured by using Brillouin optical-fiber time-domain analysis.
Abstract: Temperature distribution in silica single-mode optical fibers, from -30 to +60 degrees C, is successfully measured by using Brillouin optical-fiber time-domain analysis. A temperature measurement accuracy of 3 degrees C with a spatial resolution of 100 m is attained over a fiber length of 1.2 km.
435 citations
TL;DR: In this article, the authors describe a theoretical model that shows how stimulated Brillouin scattering (SBS) is initiated by thermally excited acoustic waves distributed within a SBS-active medium, which predicts how the SBS reflectivity, Stokes linewidth, and fluctuations in Stokes intensity depend upon the laser intensity and upon the physical properties of the medium.
Abstract: We describe a theoretical model that shows how stimulated Brillouin scattering (SBS) is initiated by thermally excited acoustic waves distributed within a Brillouin-active medium. This model predicts how the SBS reflectivity, Stokes linewidth, and fluctuations in Stokes intensity depend upon the laser intensity and upon the physical properties of the SBS medium. This model also leads to the prediction that the value of the single-pass gain (i.e., G=gIL) at the threshold for SBS is not a universal number, but depends upon the laser frequency and on the properties of the SBS medium. For typical organic liquids at room temperature, G is in the range 20--25.
427 citations
TL;DR: In this paper, a technique based on Brillouin optical fiber time-domain analysis (BOTDA) was proposed for optical fiber wound on drums at various tensions is presented, achieving better than 2*10/sup -5/ and a spatial resolution of 100 m.
Abstract: The technique is based on Brillouin optical-fiber time-domain analysis (BOTDA), which uses Brillouin interaction between counterpropagating pump and probe light waves. Experimental results for fibers wound on drums at various tensions are presented. A strain measurement accuracy of better than 2*10/sup -5/ and a spatial resolution of 100 m are achieved. >
267 citations
TL;DR: Brillouin frequency shift in two kinds of jacketed optical single-mode silica fiber, with an ultraviolet curable resin coat and a nylon coat, has been measured at temperatures ranging from -30 to +60 degrees C.
Abstract: Brillouin frequency shift in two kinds of jacketed optical single-mode silica fiber, with an ultraviolet curable resin coat and a nylon coat, has been measured at temperatures ranging from -30 to +60 degrees C. It has been found that there are two reasons for the Brillouin frequency shift change in jacketed optical fibers against temperature change. One is the Brillouin frequency shift change for bare fibers. The other is the thermal stress due to the differences in thermal expansion coefficients in bare fiber and its coating material.
182 citations
Book•
01 Jan 1990
TL;DR: In this article, the authors describe the physical optics of enhanced backscattering and surface scattering, including surface impedance boundary conditions, and the use of the Calderon projectors and the capacity operators in scattering.
Abstract: Part I: Volume Scattering. Experimental and theoretical studies on enhanced hackscattering from scatterers and rough surfaces (A. Ishimaru). Multiple scattering in dynamic systems (I. Freund). Dynamics of Brownian particles from strongly multiple light scattering (P.E. Wolf, G. Maret). Multiple scattering in dense media (P. Bruscaglioni, G. Zaccanti). Role of the inner scale of atmospheric turbulence in optical propagation and methods to measure it (A. Consortini). Diffraction tomography: Potentials and problems (L.-J. Gelius, J.J. Stamnes). The physical optics of enhanced backscattering (E. Jakeman). Part II: Surface Scattering. Scattering experiments with smoothly varying random rough surfaces and their interpretation (E.R. Mendez, K.A. O'Donnell). Measurements of angular scattering by randomly rough metal and dielectric surfaces (J.C. Dainty, M.-J. Kim, A.J. Sant). Backscattering effects in the elastic scattering of p-polarized light from a large amplitude random grating (A.A. Maradudin, E.R. Mendez, T. Michel). Electromagnetic scattering from very rough random surfaces and its connections with blazes from reflection gratings (M. Nieto-Vesperinas, J.M. Soto-Crespo). Rigorous solution of problems of scattering by large size objects (D. Maystre, M. Saillard). The method of smoothing applied to random volume and surface scattering (G.S. Brown). Scattering of EM waves from particles with random rough surfaces (R. Schiffer). Surface impedance boundary conditions used to study light scattering from metallic surfaces (R.A. Depine). The use of the Calderon projectors and the capacity operators in scattering (M. Cessenat). Part III. Non-linear Interactions. Gratings as electromagnetic field amplifiers for second harmonic generation (R. Reinisch, M. Neviere). Intrinsic instabilities of laser-irradiated surfaces (J.E. Sipe, H.M. van Driel). Brillouin scattering from thin films (G.I. Stegeman et al.) Author Index. Subject Index.
93 citations
TL;DR: In this paper, the authors measured the Brillouin gain spectra in two 250m-long single-mode fibers with GeO/sub 2/-doped core/pure-silica cladding (fiber A) and pure-Silica core/F-doped cladding(fiber B) at temperatures ranging from -40 to +60 degrees C at a wavelength of 1.32 mu m.
Abstract: Brillouin gain spectra in two 250-m-long single-mode fibers with GeO/sub 2/-doped core/pure-silica cladding (fiber A) and pure-silica core/F-doped cladding (fiber B) were measured at temperatures ranging from -40 to +60 degrees C at a wavelength of 1.32 mu m. The temperature coefficients of Brillouin frequency shift were found to be 1.17 and 1.33 MHz/ degrees C for fibers A and B, respectively. Temperature coefficients of Brillouin gain bandwidth were found to be -0.12 and -0.10 MHz/ degrees C. These measurements provide useful information for applications of stimulated Brillouin scattering. >
81 citations
76 citations
TL;DR: In this paper, an observation of intermodal forward stimulated Brillouin scattering at 514.5 nm in dual-mode optical fibres is reported, where the FSBS signal is shifted by 16.6 MHz and does not depend significantly on the laser linewidth.
Abstract: Observation of intermodal forward stimulated Brillouin scattering at 514.5 nm in dual-mode optical fibres is reported. The FSBS signal is shifted by 16.6 MHz and, unlike in normal background SBS, does not depend significantly on the laser linewidth. The Brillouin gain in backward and forward directions is compared.
75 citations
TL;DR: It was found that NDS fibers operated at a wavelength of 1550 nm can be widely deployed in multichannel systems both for the long-haul and information distribution transmissions, if the signal waveform distortion due to fiber chromatic dispersion is precluded.
Abstract: Transmission limitations due to stimulated Brillouin scattering and four-wave mixing processes are investigated for optical frequency division multiplexing (FDM) systems. The applicability of the dispersion-shifted (DS) and nondispersion-shifted (NDS) fibers is discussed, taking account of channel frequency separation, total channel numbers, input signal power, transmission length, and receiver sensitivity degradation. Experimental results on Brillouin gain spectra and the wave generation efficiency in four-wave mixing processes are also presented to discuss the applicability of the two types of single-node fiber. It was found that NDS fibers operated at a wavelength of 1550 nm can be widely deployed in multichannel systems both for the long-haul and information distribution transmissions, if the signal waveform distortion due to fiber chromatic dispersion is precluded. The delay equalizer will be useful for a high-speed system employing bit rates over 10 Gb/s and repeaterless spans over 300 km. For such an application, DS fiber is preferable. Concerning information distribution network applications, the NDS fiber should be more attractive as a transmission medium for FDM system applications. >
65 citations
TL;DR: In this paper, a Q-switched mode-locked 532-nm laser was used to satisfy the input resonance condition of various low-order (l = 2 to l = 4) TE and TM morphology-dependent resonances in 23.0-23.7-μm-diameter ethanol droplets.
Abstract: Programmed size ramping of an aerosol stream permits a Q-switched mode-locked 532-nm laser to satisfy periodically the input resonance condition of various low-order (l = 2 to l = 4) TE and TM morphology-dependent resonances in 23.0–23.7-μm-diameter ethanol droplets. The resulting size-versus-amplitude spectra of stimulated Raman scattered light revealed high-Q modes that are not normally observed in elastic scattering. Simultaneous elastic scattering measurements permit unambiguous identification of these input resonances. The relative output intensities of stimulated Raman scattering and time histories imply that the Q of the l = 2 modes is degraded to a value of 107 by the departure of the droplet from an ideal homogeneous sphere.
01 Aug 1990
TL;DR: In this article, it is shown that for long-haul transmission systems with fiber lengths exceeding 100 km, typical channel separation of 10 GHz, and few channels, the maximum allowed input power per channel, P/sub max/, is limited by SBS (stimulated Brillouin scattering) to about 5 dBm.
Abstract: Various nonlinear optical interactions in single-mode fibers that are used in coherent FDM (frequency division multiplexed) transmission systems are examined. It is these nonlinearities that lead to crosstalk between channels, power losses, and deleterious fluctuations, which in turn limit the power of the transmitted light and the number of allowed channels, and dictate the channel allocations. It is shown that, for long-haul transmission systems with fiber lengths exceeding 100 km, typical channel separation of 10 GHz, and few channels, the maximum allowed input power per channel, P/sub max/, is limited by SBS (stimulated Brillouin scattering) to about 5 dBm. As the number of channels increases, FWM (four wave mixing) becomes the limiting process with P/sub max/ of about -5 dBm, whereas above several hundred channels SRS (stimulated Raman scattering) becomes dominant with P/sub max/ of about -5 dBm. For local area networks with shorter lengths, the results are similar, except that the values of P/sub max/ are uniformly higher by about 5 dB. >
TL;DR: In this article, the solutions of stimulated Brillouin scattering (SBS) equations in single mode fibres are reported, and how the results can be used to enable easy and flexible evaluation of the power budget requirements in optical fiber transmission systems.
Abstract: The solutions of stimulated Brillouin scattering (SBS) equations in single mode fibres are reported, and it is shown how the results can be used to enable easy and flexible evaluation of the power budget requirements in optical fibre transmission systems.
TL;DR: In this paper, the temporal profiles of the laser pulse, SRS, and SBS are simultaneously measured with a streak camera (100psec resolution) with a single-mode laser beam.
Abstract: The intensity threshold for stimulated Raman scattering (SRS) with a single-mode laser beam is noted to be ≈3 times lower than that with a multimode beam. The intensity threshold for stimulated Brillouin scattering (SBS) from droplets is lower than that for SRS. The temporal profiles of the laser pulse, SRS, and SBS are simultaneously measured with a streak camera (100-psec resolution). The first SBS pulse always occurs earlier than the first SRS pulse. In addition, the subsequent series of SBS and SRS pulses is temporally correlated; i.e., the minimum of the (n + 1)th SBS pulse occurs when the nth SRS pulse reaches a maximum. The second-harmonic beam of a single-mode or multimode Q-switched Nd:YAG laser is tightly focused at the center of the droplet’s illuminated face in order to avoid excitation of any morphology-dependent resonances of a droplet. We conclude that, for single-mode laser excitation of droplets, the internal SBS pumps the SRS.
TL;DR: The dynamic structure factor of room-temperature 36 Ar is investigated at two densities and at very low momentum transfer to find linearized hydrodynamics agrees with the experimental data only at the higher density.
Abstract: We have investigated the dynamic structure factor of room-temperature 36 Ar at two densities (0.25 and 0.63 times the critical) and at very low momentum transfer (0.3<κ<1.3 nm −1 ). Linearized hydrodynamics agrees with the experimental data only at the higher density and κ<1 nm −1
TL;DR: In this article, Brillouin scattering is used to measure the longitudinal-phonon dispersion curves for a suspension of hard-sphere colloids and two distinct propagating acoustic excitations are observed when the wavelength of the sound is comparable to, or smaller than, the size of the spheres.
Abstract: We use Brillouin scattering to measure the longitudinal-phonon dispersion curves for a suspension of hard-sphere colloids. Two distinct propagating acoustic excitations are observed when the wavelength of the sound is comparable to, or smaller than, the size of the spheres. One excitation has a velocity intermediate between that of the fluid and the solid phases and is interpreted as an acoustic wave propagating through the composite medium of fluid and solid spheres. The second has a velocity slower than both that of the solid and that of the fluid phase and is interpreted as a coupled interfacial, or Stoneley, wave.
TL;DR: In this article, the relaxation data for 0.4Ca(NO3)20.6KNO3 obtained for temperatures above 100°C by ultrasound measurements and by normal as well as by stimulated Brillouin scattering experiments are reanalyzed in order to show that they all obey the time temperature superposition principle with the same Kohlrausch model as master function.
TL;DR: In this paper, optical feedback was used to enhance the phase-conjugation process of stimulated Brillouin scattering in a pulsed Nd:YAG laser system and numerical simulations were derived.
Abstract: The technique of using optical feedback to enhance the phase-conjugation process of stimulated Brillouin scattering is experimentally and theoretically investigated. Several feedback arrangements are experimentally studied and demonstrate the ability to reduce significantly the threshold power requirement, enhance the efficiency, and improve the phase-conjugate fidelity of the Brillouin process. Steady-state analytical solutions for the interactions, including the effects of laser pump depletion, are derived. Numerical modeling is used to introduce the more complete transient effects. Good agreement between the experimental results using a pulsed Nd:YAG laser system and the numerical simulations is achieved. The results are applicable, with modification, to other forms of stimulated scattering and also to self-pumped photoreflection. >
TL;DR: In this article, the elastic properties and equation of state for SiO2 and GeO2 glasses were obtained from the Brillouin scattering measurements with respect to pressure, and the anomalous behavior was reconciled with a model based on the pressure dependent bending of the oxygen angles in both glass types.
Abstract: Brillouin and Raman Scattering Spectra in SiO2 and GeO2 glasses have been measured in a diamond anvil cell up to pressures of 14 GPa. The elastic properties and equation of state for each glass type were obtained from the Brillouin scattering measurements with respect to pressure. Both elastic constants and compressibility of SiO2 and GeO2 showed anomalous behavior with respect to pressure. This anomalous behavior is reconciled with a model based on the pressure dependent bending of the oxygen angles in both glass types. The Raman measurements corroborate the conclusions from the Brillouin scattering results, namely that the SiO2 and GeO2 bond angles are changing with pressure or the oxygen angle distribution is changed without bond breaking.
TL;DR: In this article, the modulation wavelength dependence of the surface-wave velocity in Cu/Ni superlattices has been investigated using Brillouin scattering, which is the first compositionally modulated system to be studied by this technique.
Abstract: The modulation wavelength dependence of the surface‐wave velocity in Cu/Ni superlattices has been investigated using Brillouin scattering. It is the first compositionally modulated system to be studied by this technique and the first for which elastic properties have been determined by both ‘‘macroscopic’’ methods and Brillouin scattering. Contrary to the enhancements previously reported in the biaxial modulus and in the Young’s modulus, the modulus associated with the surface‐wave velocity shows no evidence of anomalous behavior.
TL;DR: In this article, the authors show that the stimulated Brillouin scattering gain of methane can be systematically varied by the addition of helium, and the gain variation is explained in terms of a transient gain model in which the dominant effect of the helium is to increase the Brillounin linewidth (acoustic attenuation).
Abstract: Experimental measurements are presented that show that the stimulated Brillouin scattering gain of methane, and hence the nature of the competition between stimulated Brillouin scattering and stimulated Raman scattering, can be systematically varied by the addition of helium. The gain variation is explained in terms of a transient gain model in which the dominant effect of the helium is to increase the Brillouin linewidth (acoustic attenuation). Broadening mechanisms are discussed. At methane and helium partial pressures of 19 and 41.8 kTorr (25 and 55 atm), respectively, backward stimulated Raman scattering dominates stimulated Brillouin scattering when the 532-nm pump energy exceeds 160 mJ.
TL;DR: In this article, a high pressure oxygen cell was used to generate vibrational stimulated Raman scattering, using a Q-switched laser, with peak first-Stokes conversion efficiencies of 6% and direct use of the cell output for stimulating Raman pumping of oxygen in room air to the first vibrationally excited level.
Abstract: A high-pressure oxygen cell has been used to generate vibrational stimulated Raman scattering, using a Q-switched laser. Peak first-Stokes conversion efficiencies of 6% are reported, and direct use of the cell output for stimulated Raman pumping of oxygen in room air to the first vibrationally excited level is demonstrated. Coherent anti-Stokes Raman spectroscopy is used to study the density dependence of the 298-K Q-branch line shape in the 5–31-amagat range, with the results compared with spectral models that incorporate the effects of intermolecular rotational energy transfer.
TL;DR: Experimental Brillouin-scattering studies of fast-ion conductors at high temperatures and complementary computer simulations are reviewed in this article, where the behavior of the acoustic-mode frequencies and elastic constants below and above the transition temperature to the state of highionic conductivity is examined.
Abstract: Experimental Brillouin-scattering studies of fast-ion conductors at high temperatures and complementary computer simulations are reviewed. Several different compounds are considered: fluorites, cubic zirconias and rare-earth trifluorides. The behaviour of the acoustic-mode frequencies and elastic constants below and above the transition temperature to the state of high-ionic conductivity is examined. Static-lattice and defect-energy calculations which provide theoretical insights into the diffuse-phase transition, and provide explanations of the anharmonic and defect contributions to the observed reductions in elastic constants, are discussed.
TL;DR: In this paper, the authors showed that the effect of aberration on the output signal-to-noise ratio of a high-gain Brillouin amplifier can be as much as a factor of 3, depending on the nature of the aberration.
Abstract: Amplification of a weak input signal (~0.5 pJ) in a high-gain (G = 109) Brillouin amplifier has resulted in an output signal-to-noise ratio of 85:1, within a factor of 4 of the theoretical estimate. For a near-diffraction-limited Gaussian pump beam this noise increases exponentially with pump intensity with the same gain coefficient as for an input signal. When the pump beam is aberrated, the effective gain coefficient for the conjugate is enhanced by as much as a factor of 3, depending on the nature of the aberration. The enhancement factor J is found to vary significantly when the laser beam passes through different regions of the aberrator.
TL;DR: Stimulated Brillouin scattering beam combining is shown to be extremely sensitive to optical misalignments, especially for beam displacements normal to the plane defined by the beams' propagation paths.
Abstract: Stimulated Brillouin scattering beam combining is shown to be extremely sensitive to optical misalignments. For the coupling of two overlapping beams, the angular misalignment bandwidth is of the order of 1 mrad, which corresponds to a separation of +/-0.64 beam spot diameter. This occurs for beam displacements normal to the plane defined by the beams' propagation paths.
TL;DR: An experimental study of Brillouin two-beam coupling in CS2 at 1.06 μm in the regime below the pump’s stimulated BrillouIn scattering threshold, finding no competitive self-SBS of the pump was observed despite operation near the SBS threshold.
Abstract: We report an experimental study of Brillouin two-beam coupling in CS2 at 1.06 μm in the regime below the pump’s stimulated Brillouin scattering (SBS) threshold. Angular discrimination between the pump and signal beams is employed. No competitive self-SBS (phase conjugation) of the pump was observed despite operation near the SBS threshold. Image intensification by a factor of 300 is demonstrated with this configuration.
TL;DR: In this paper, the sputtered CoNiPt film was studied by Brillouin scattering and it was shown that the spin-wave spectra in the film are remarkably broadened with width 13 GHz (full width at half maximum), which is much larger than the width of 3 GHz in a film prepared by vapor deposition.
Abstract: Sputtered CoNiPt films prepared for high‐density magnetic recording media have been studied by Brillouin scattering. The spin‐wave spectra in the film are remarkably broadened with width 13 GHz (full width at half maximum), which is much larger than the width of 3 GHz in a film prepared by vapor deposition. Observation by a transmission electron microscope has clarified that the sputtered film consists of Co crystallites with a diameter of 50–100 A, which are separated from each other. The remarkable damping of the spin waves in the sputtered CoNiPt film is caused by the film structure. The film is, however, elastically homogeneous, which is known from the undamped surface acoustic wave spectra. The result shows the segregation of the nonmagnetic Pt‐related alloys takes place between the Co crystallites. The exchange stiffness constant was determined as 2.4×10−9 Oe cm2 in the sputtered film, which is 1/1.7 that in the vapor‐deposited films.
TL;DR: In this paper, the phase transition of TlH 2 PO 4 was shown to be a ferroelastic one induced by an instability of the transverse acoustic mode which corresponds to the shear strain x 5.
Abstract: Temperature dependence of the acoustic modes of TlH 2 PO 4 has been observed by the Brillouin scattering around its higher phase transition point at 357 K ( T tr ). The elastic constant c 55 obtained by the angular-dependent spectra shows softening with the Curie-Weiss law in both phases. The phase transition is concluded to be a ferroelastic one induced by an instability of the transverse acoustic mode which corresponds to the shear strain x 5 . The angular dependence of the spectra reveals a typical monoclinicity below T tr . The two-dimensionality of hydrogen-bonded network does not affect the dynamical property of the phase transition mechanism.
TL;DR: What is to the authors' knowledge the first high-resolution Brillouin gain spectrum in a solid is reported, observed with good resolution and a high signal-to-noise ratio.
Abstract: We report what is to our knowledge the first high-resolution Brillouin gain spectrum in a solid. Resonances corresponding to longitudinal (compressional) and transverse (shear) acoustic waves in fused silica are observed with good resolution and a high signal-to-noise ratio. Absolute gain coefficients, linewidths, and Brillouin frequency shifts are measured. The agreement with previously measured values is good.
TL;DR: Analytical solutions of the nonlinear fluid equations predict formation of the periodic sequence of shock waves and compare well with the results of numerical simulations of the full set of the hydrodynamical and Maxwell equations, which reveal the oscillatory structure of the shock.
Abstract: The nonlinear properties of ion acoustic waves produced by a strong ponderomotive force have been analyzed in the regime where the amplitude of ponderomotive potential is comparable to the plasma thermal energy density. Analytical solutions of the nonlinear fluid equations predict formation of the periodic sequence of shock waves. These solutions compare well with the results of numerical simulations of the full set of the hydrodynamical and Maxwell equations, which also reveal the oscillatory structure of the shock. These results are applied to the analysis of stimulated Brillouin scattering.