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Showing papers on "Brillouin scattering published in 2008"


Journal ArticleDOI
TL;DR: A differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) for centimeter spatial resolution sensing using meter equivalent pulses is proposed.
Abstract: A differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) for centimeter spatial resolution sensing using meter equivalent pulses is proposed. This scheme uses the time domain waveform subtraction at the same scanned Brillouin frequency obtained from pulse lights with different pulse-widths (e.g. 50ns and 49ns) to form the differential Brillouin gain spectrum (BGS) at each fiber location. The spatial resolution is defined by the average of the rise and fall time equivalent fiber length for a small stress section rather than the pulse-width difference equivalent length. The spatial resolution of 0.18m for the 50/49ns pulse pair and 0.15m for 20/19ns pulse pair over 1km sensing length with Brillouin frequency shift accuracy of 2.6MHz are demonstrated.

376 citations


Journal ArticleDOI
TL;DR: A Brillouin optical correlation-domain reflectometry (BOCDR), which can measure the distribution of strain and/or temperature along an optical fiber from a single end, by detecting spontaneous BrillouIn scattering with controlling the interference of continuous lightwaves is proposed.
Abstract: We propose a Brillouin optical correlation-domain reflectometry (BOCDR), which can measure the distribution of strain and/or temperature along an optical fiber from a single end, by detecting spontaneous Brillouin scattering with controlling the interference of continuous lightwaves. In a pulse-based conventional Brillouin optical time-domain reflectometry (BOTDR), it is difficult in principle to achieve a spatial resolution less than 1 m, and the measurement time is as long as 5-10 minutes. On the contrary, the continuous-wave-based BOCDR can exceed the limit of 1-m resolution, and realize much faster measurement and random access to measuring positions. Spatial resolution of 40 cm was experimentally demonstrated with sampling rate of 50 Hz.

280 citations


Journal ArticleDOI
TL;DR: In this article, a moving acoustic grating is generated by stimulated Brillouin scattering between writing beams in one polarization and used to reflect an orthogonally polarized reading beam at different wavelengths.
Abstract: We report a novel kind of all-optical dynamic grating based on Brillouin scattering in a polarization maintaining fiber (PMF). A moving acoustic grating is generated by stimulated Brillouin scattering between writing beams in one polarization and used to reflect an orthogonally polarized reading beam at different wavelengths. The center wavelength of the grating is controllable by detuning the writing beams, and the 3 dB bandwidth of approximately 80 MHz is observed with the tunable reflectance of up to 4% in a 30 m PMF.

246 citations


Journal ArticleDOI
TL;DR: It is found that for a wide range of practical pump powers and for sufficiently long fibers with typical SBS and birefringence parameters, the signal aligned for maximum SBS interaction will enter/emerge from the fiber with its electric field closely tracing the same ellipse in space as that of the pump at the corresponding side of the fiber, albeit with the opposite sense of rotation.
Abstract: The polarization properties of stimulated Brillouin scattering (SBS) amplification or attenuation in standard single-mode fibers are examined through vectorial analysis, simulation and experiment. Vector propagation equations for the signal wave, incorporating SBS and birefringence, are derived and analyzed in both the Jones and Stokes spaces. The analysis shows that in the undepleted pump regime, the fiber may be regarded as a polarization-dependent gain (or loss) medium, having two orthogonal input SOPs, and corresponding two orthogonal output SOPs, for the signal, which, respectively, provide the signal with maximum and minimum SBS amplification (or attenuation). Under high Brillouin gain conditions and excluding zero-probability cases, the output SOP of arbitrarily polarized input signals, would tend to converge towards that of maximum SBS gain. In the case of high SBS attenuation the output SOP of an arbitrarily polarized signal would approach the output SOP corresponding to minimum attenuation. It is found that for a wide range of practical pump powers (<= 100 mW) and for sufficiently long fibers with typical SBS and birefringence parameters, the signal aligned for maximum SBS interaction will enter/emerge from the fiber with its electric field closely tracing the same ellipse in space as that of the pump at the corresponding side of the fiber, albeit with the opposite sense of rotation. The analytic predictions are experimentally demonstrated for both Stokes (amplification) and anti-Stokes (attenuation) signals.

195 citations


BookDOI
22 Dec 2008
TL;DR: The fundamental physics of slow light in different media are discussed in this paper, where the authors present a detailed discussion of the structural, application, and tradeoff of the slow light.
Abstract: Fundamental Physics of Slow Light in Different Media Slow Light in Atomic Vapors R. M. Camacho and J. C. Howell Slow and Fast Light in Semiconductors S.-W. Chang and S. L. Chuang Slow Light in Optical Waveguides Z. Zhu, D. J. Gauthier, A. L. Gaeta, and R. W. Boyd Slow Light in Photonic Crystal Waveguides T. F. Krauss Slow Light in Periodic Photonic Structures Periodic Coupled Resonator Structures J. K.S. Poon, P. Chak, J. E. Sipe, and A. Yariv Resonator-Mediated Slow Light: Novel Structures, Applications, and Tradeoffs A. B. Matsko and L. Maleki Disordered Optical Slow-Wave Structures: What Is the Velocity of Slow Light? S. Mookherjea Slow Light in Fibers Slow and Fast Light Propagation in Narrow Band Raman-Assisted Fiber Parametric Amplifiers G. Eisenstein, E. Shumakher, and A. Willinger Slow and Fast Light Using Stimulated Brillouin Scattering: A Highly Flexible Approach A L. ThA (c)venaz Slow Light and Nonlinear Phenomena Nonlinear Slow-Wave Structures A. Melloni and F. Morichetti Slow Light Gap Solitons J.T. Mok, I. C.M. Littler, M. Ibsen, C. Martijn de Sterke, and B. J. Eggleton Coherent Control and NonlinearWave Mixing in Slow LightMedia Y. Rostovtsev Dynamic Structures for Storing Light Stopping and Storing Light in Semiconductor QuantumWells and OpticalMicroresonators N. H. Kwong, J. E. Sipe, R. Binder, Z. Yang, and A. L. Smirl Stopping Light via Dynamic Tuning of Coupled Resonators S. Fan and M. L. Povinelli Applications Bandwidth Limitation in Slow Light Schemes J. B. Khurgin Reconfigurable Signal Processing Using Slow-Light-Based Tunable Optical Delay Lines A. E. Willner, B. Zhang, and L. Zhang Slow Light Buffers for Packet Switching R. S. Tucker Application of Slow Light to Phased Array Radar Beam Steering Z. Dutton, M. Bashkansky, and M. Steiner Index

166 citations


Journal ArticleDOI
TL;DR: In this paper, anharmonic oscillator model, using the normalized photon energy, gives an excellent fit to the data over three orders of magnitude, and measured third order nonlinearities increase with the value of x, and are up to about 1000 times larger than silica for As 2 Se 3 glass.
Abstract: High purity chalcogenide glasses were prepared in the series As 2 S (3− x ) Se x where x = 0 to 3. The measured third order non-linearities increase with the value of x , and are up to about 1000 times larger than silica for As 2 Se 3 glass. We show that the anharmonic oscillator model, using the normalized photon energy, gives an excellent fit to the data over three orders of magnitude. Single mode optical fibers based on As 2 S 3 and As 2 Se 3 glasses have been fabricated using the double crucible technique and the Stimulated Brillouin Scattering (SBS) investigated. The threshold intensity for the SBS process was measured and used to estimate the Brillouin gain coefficient. Preliminary results indicate record high values for the figure of merit and theoretical gain, compared to silica, which bodes well for slow-light based applications in chalcogenide fibers.

143 citations


Journal ArticleDOI
TL;DR: In this article, a micro-Brillouin light scattering spectroscopy technique was proposed for spin wave dynamics in magnetic nanostructures, which offers advantages for studies of small magnetic squares with closure domain structure and magnetic nanoelements similar to those used in magnetic random access memory.
Abstract: We describe a new technique, micro-Brillouin light scattering spectroscopy, for investigation of spin wave dynamics in magnetic nanostructures. The technique offers advantages for studies of small magnetic squares with closure domain structure and magnetic nanoelements similar to those used in magnetic random access memory. The technique is particularly effective in two-dimensional mapping of spin waves excited by a single nanocontact due to the spin torque transfer effect.

138 citations


Journal ArticleDOI
TL;DR: By exploiting Raman amplification with an incoherent pump, the amplified signal is shown to develop a series of temporal intensity spikes whose peak power follows a power-law probability distribution.
Abstract: We report experimental observation and characterization of rogue wave-like extreme value statistics arising from pump-signal noise transfer in a fiber Raman amplifier. Specifically, by exploiting Raman amplification with an incoherent pump, the amplified signal is shown to develop a series of temporal intensity spikes whose peak power follows a power-law probability distribution. The results are interpreted using a numerical model of the Raman gain process using coupled nonlinear Schrodinger equations, and the numerical model predicts results in good agreement with experiment.

128 citations


Journal ArticleDOI
TL;DR: Two hypersonic phononic gaps of different nature in three-dimensional colloidal films of nanospheres using Brillouin light scattering are observed, originating from the interaction of the band of quadrupole particle eigenmodes with the acoustic effective-medium band and the hybridization gap is robust.
Abstract: We report on the observation of two hypersonic phononic gaps of different nature in three-dimensional colloidal films of nanospheres using Brillouin light scattering One is a Bragg gap occurring at the edge of the first Brillouin zone along a high-symmetry crystal direction The other is a hybridization gap in crystalline and amorphous films, originating from the interaction of the band of quadrupole particle eigenmodes with the acoustic effective-medium band, and its frequency position compares well with the computed lowest eigenfrequency Structural disorder eliminates the Bragg gap, while the hybridization gap is robust

106 citations


Journal ArticleDOI
TL;DR: This phase-conjugated laser amplifier system consisting of two thermally-edge-controlled zigzag slab amplifiers and a stimulated Brillouin scattering mirror produces an average power of 213 W at 10 Hz with an optical-to-optical conversion efficiency of 11.7% and a near-diffraction-limited beam.
Abstract: We report a high-average-power and high-pulse-energy diode-pumped Nd:glass laser amplifier system consisting of two thermally-edge-controlled zigzag slab amplifiers and a stimulated Brillouin scattering mirror. This phase-conjugated system produces an average power of 213 W at 10 Hz in a 8.9 ns pulse (2.4 GW peak power) with an optical-to-optical conversion efficiency of 11.7% and a near-diffraction-limited beam. To the best of our knowledge, this is the highest performance from a Nd:glass-based laser amplifier system ever built.

103 citations


Journal ArticleDOI
TL;DR: In this article, a model based on the Bloch wave approach was proposed for spin wave propagation in an array of magnetic stripes coupled by dynamic dipole interaction, and it was demonstrated that this structure supports propagation of discrete spin waves at any angle with respect to the stripes length.
Abstract: Collective spin wave modes propagating in an array of magnetic stripes coupled by dynamic dipole interaction are investigated by Brillouin light scattering. It is demonstrated that this structure supports propagation of discrete spin waves at any angle with respect to the stripes length. The data are interpreted using a theoretical model based on the Bloch wave approach. It is shown that, due to the one-dimensional artificial periodicity of the medium, the gaps in the spin wave spectrum are partial: the frequency passbands for propagation along the direction of periodicity overlap with the stop bands for propagation along the stripes.

Journal ArticleDOI
TL;DR: Experimental and theoretical investigations on spontaneous and stimulated Brillouin scattering during operation of a high-power single-frequency polarization-maintaining ytterbium doped fiber amplifier and their results have been compared with a theoretical model based on coupled intensity equations.
Abstract: We report on theoretical and experimental investigations on spontaneous and stimulated Brillouin scattering during operation of a high-power single-frequency polarization-maintaining ytterbium doped fiber amplifier. For different amplifier configurations with co- and counter-propagating seed and pump radiation the evolution of Brillouin scattering spectra was investigated with a heterodyne detection scheme. Spontaneous Brillouin gain spectra at low powers were additionally investigated using a pump-probe technique. The data obtained from these experiments have been compared with a theoretical model based on coupled intensity equations. A Brillouin scattering suppression has been investigated theoretically and experimentally with externally applied temperature gradients along the fiber resulting in up to 3.5 dB suppression and 115 W of amplifier output power.

Journal ArticleDOI
TL;DR: In this paper, the authors present extensive stimulated Brillouin scattering (SBS) results from experiments and modeling for four different photonic crystal fibers (PCFs) with core diameters ranging from 8 to 1.7 μm.
Abstract: We present extensive stimulated Brillouin scattering (SBS) results from experiments and modeling for four different photonic crystal fibers (PCFs) with core diameters ranging from 8 to 1.7 μm. These results reveal several SBS characteristic features of small-core PCFs, high thresholds, and acoustic peaks, which are due to their antiguiding nature and highly multimode acoustic character. The nature of what we believe to be new acoustic modes is examined in the light of the large variations observed in the Brillouin gain, Brillouin threshold, and Brillouin shift with decreasing core diameter and optical wavelength.

Journal ArticleDOI
TL;DR: In this article, a strong relaxation mode was observed in the paraelectric phase of barium titanate (BaTiO3) single crystals by Brillouin scattering study and was found to correlate with the softening of the longitudinal acoustic mode and the increase in the hypersonic damping.
Abstract: A strong relaxation mode was observed in the paraelectric phase of barium titanate (BaTiO3) single crystals by Brillouin scattering study and was found to correlate with the softening of the longitudinal acoustic mode and the increase in the hypersonic damping. These observations support the existence of polar percursors and their electrostrictive coupling with the strain caused by the acoustic waves, consistent with former studies evidencing off-centered Ti ions in the high-symmetry cubic phase. A critical slowing down has been clearly observed in the vicinity of the cubic-tetragonal phase transition, indicating order-disorder component contributes to the phase transition of BaTiO3.

Journal ArticleDOI
TL;DR: In this paper, a linear cavity Brillouin fiber laser (BFL) is proposed and demonstrated for multi-wavelength operation, which uses a single mode fiber (SMF) as a nonlinear gain medium.
Abstract: A linear cavity Brillouin fiber laser (BFL) is proposed and demonstrated for multi-wavelength operation. The BFL uses a single mode fiber (SMF) as a non-linear gain medium and an optical circulator to generate a linear cavity resonator. Two couplers are used to inject the Brillouin Pump (BP) and tap the BFL output respectively. The effect of the coupler ratio on the BFL performance is studied by keeping constant the ratio of the first coupler and varying the ratio of the second coupler. 11 simultaneous lines with a line spacing of 0.8 nm are obtained at a BP of 11.7 dBm and a coupler ratio of 95:5. The laser output is stable at room temperature with 5 lines obtained at above – 30 dBm, and has the largest signal to noise ratio observed at the remaining lines. The proposed BFL has the advantage of being able to operate at any wavelength and is only dependent on the available BP wavelength.

Proceedings ArticleDOI
TL;DR: In this article, a ramp-like acoustic index contrast of 0.09 was achieved for an Al/Ge fixme-co-doped large mode area (LMA) gain fiber.
Abstract: 11.2 dB suppression of stimulated Brillouin scattering (SBS) in an Yb-doped, Al/Ge co-doped large mode area (LMA) gain fiber is demonstrated with a ramp-like acoustic index profile exhibiting an acoustic index contrast of 0.09 and acoustic index slope of 0.01/μm.

Journal ArticleDOI
TL;DR: A new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals to achieve high frequency stability without using a supercavity.
Abstract: We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.

Journal ArticleDOI
TL;DR: In this article, a Brillouin distributed fiber sensor based on optical time-domain analysis is proposed, which achieves resolution of 7 m all over a 47 km single-mode fiber and resolution down to 30 cm in a few kilometer fiber.
Abstract: A novel configuration for a Brillouin distributed fiber sensor based on Brillouin optical time-domain analysis is proposed. This configuration eliminates many intensity noise issues found in previous schemes. Resolution of 7 m all over a 47 km single-mode fiber was achieved and resolution down to 30 cm in a few kilometer fiber. Noise reduction makes possible measurements with a 16 times averaging.

Journal ArticleDOI
TL;DR: An enhanced multiwavelength L-band Brillouin-erbium fiber laser (BEFL) is demonstrated, in which the BrillouIn pump is pre-amplified before entering the single-mode fiber, and the number of output channels is enhanced within the same tuning range.
Abstract: We demonstrate an enhanced multiwavelength L-band Brillouin-erbium fiber laser (BEFL), in which the Brillouin pump is pre-amplified before entering the single-mode fiber. The Brillouin pump pre-amplification provided by the Erbium-doped fiber has created higher intensity of Brillouin Stokes line generated in the single-mode fiber that leads to the homogenous gain saturation. Thus the built-up of self-lasing cavity modes is suppressed in a wider wavelength range. In contrary to the conventional linear-cavity BEFL, the number of output channels is enhanced within the same tuning range.

Journal ArticleDOI
TL;DR: In this paper, the authors investigate polarization squeezing of ultrashort pulses in optical fiber, over a wide range of input energies and fiber lengths, and compare experimental data and quantum dynamical simulations to find good quantitative agreement.
Abstract: We investigate polarization squeezing of ultrashort pulses in optical fiber, over a wide range of input energies and fiber lengths. Comparisons are made between experimental data and quantum dynamical simulations to find good quantitative agreement. The numerical calculations, performed using both truncated Wigner and exact $+P$ phase-space methods, include nonlinear and stochastic Raman effects, through coupling to phonon variables. The simulations reveal that excess phase noise, such as from depolarizing guided acoustic wave Brillouin scattering, affects squeezing at low input energies, while Raman effects cause a marked deterioration of squeezing at higher energies and longer fiber lengths. We also calculate the optimum fiber length for maximum squeezing.

Journal ArticleDOI
TL;DR: In this paper, the backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser is examined in the kinetic regime using particle-in-cell simulations and wavefront bowing of electron plasma waves due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SBS regime for the first time.
Abstract: Backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser are examined in the kinetic regime using particle-in-cell simulations. The SRS reflectivity measured as a function of the laser intensity in a single hot spot from two-dimensional (2D) simulations shows a sharp onset at a threshold laser intensity and a saturated level at higher intensities, as obtained previously in Trident experiments [D. S. Montgomery et al., Phys. Plasmas 9, 2311 (2002)]. In these simulations, wavefront bowing of electron plasma waves (ion acoustic waves) due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) [H. A. Rose, Phys. Plasmas 12, 12318 (2005)] is shown to occur in both two- and three-dimensional SRS simulations. The key physics underlying nonlinear saturation of SRS is identified as a combination of wavefront bowing, TPMI, and self-focusing of...

Journal ArticleDOI
TL;DR: Experimental results confirm that, differently from Raman-based sensors, pulse coding affects the stimulated Brillouin threshold, resulting in lower optimal input power levels; these features allow one to achieve high sensing performance avoiding the use of high peak power pulses.
Abstract: A theoretical and experimental analysis of optical pulse coding techniques applied to distributed optical fiber temperature sensors based on spontaneous Brillouin scattering using the Landau-Placzek ratio (LPR) scheme is presented, quantifying in particular the impact of Simplex coding on stimulated Brillouin and Raman power thresholds. The signal-to-noise ratio (SNR) enhancement and temperature resolution improvement provided by coding are also characterized. Experimental results confirm that, differently from Raman-based sensors, pulse coding affects the stimulated Brillouin threshold, resulting in lower optimal input power levels; these features allow one to achieve high sensing performance avoiding the use of high peak power pulses.

Journal ArticleDOI
Abstract: In this paper, Brillouin gain performances of tellurite fiber are investigated for photonics applications. We demonstrate stimulated Brillouin amplification and lasing and the simulated performance of slow light generation in a single-mode tellurite fiber. A Brillouin gain of 29 dB is achieved in a 100-m tellurite fiber with a pump power of 10 mW at 1550 nm. A peak value of Brillouin gain coefficients of 1.6989 X 10-10 m/W is measured on the base of gain characteristics. An all-fiber Brillouin laser with the maximum unsaturated power of 54.6 mW at 1550 nm and a slope efficiency of 38.2% is achieved from a 200-m tellurite fiber by employing a ring cavity. Furthermore, widely tunable (~27 nm) Brillouin comb laser with 26 lines spaced at 7.97 GHz is obtained from the ring laser cavity including an erbium-doped fiber amplifier (EDFA). A simple theoretical model based on laser threshold theory successfully explains the properties of Brillouin comb lasers. Stimulated Brillouin scattering (SBS)-induced time delay per unit power and per unit length is also calculated using the measured data of Brillouin gain coefficients. A peak value of 0.09246 ns/mW/m and a time delay slope efficiency of 1.75 ns/dB are obtained for this tellurite fiber. Potential performance of a tellurite fiber for slow light generation is clarified on the base of Brillouin gain characteristic. Our results show that tellurite fiber is a promising gain medium for Brillouin fiber amplifiers, lasers, and slow light generation due to its low background loss and large Brillouin gain coefficient.

Journal ArticleDOI
TL;DR: In this paper, the authors presented a pilot application of Brillouin optical time domain reflectometry to measure strain profiles along the steel girders of a continuous slab-on-girder bridge subjected to diagnostic load testing.
Abstract: Fiber optic sensing technologies are emerging as valid alternatives for the health monitoring of civil structures. Distributed sensors based on Brillouin scattering add the unique capability of measuring strain and temperature profiles along optical fibers. Measurement is performed by establishing the correlation between fiber strain and temperature, and the frequency shift of the Brillouin backscattered light induced by a monochromatic light pulse. The technology holds potential for use on large structures and integrated transportation infrastructure. Its effectiveness has been assessed through scaled laboratory experiments, whereas field validation is limited to very few demonstration projects conducted to date. This paper presents a pilot application of Brillouin optical time domain reflectometry to measure strain profiles along the steel girders of a continuous slab-on-girder bridge subjected to diagnostic load testing. One of the exterior continuous girders required heat-straightening after falling during construction due to wind. The significance of applying a distributed measurement technique lies in the potential to assess the global girder response, which would be impractical and uneconomical using discrete measurement techniques. A 1.16 km long sensing circuit was installed onto the web of four girders. The circuit comprises bare optical fiber sensors, and a novel adhesively bonded fiberglass tape with embedded sensing fibers for strain measurement and thermal compensation. The strain profiles were first converted into deflection profiles and validated against discrete deflection measurements performed with a high-precision total station system. Structural assessment based on comparison of the strain profiles with the results of three-dimensional finite-element analysis of the bridge superstructure, and with specification mandated criteria, indicated that the response of the girder under investigation was within the design limits, and did not pose serviceability concerns. Factors that may affect measurement accuracy are finally discussed on the basis of the experimental and numerical results.

Journal ArticleDOI
TL;DR: The ratio of Raman to Brillouin gain coefficient of a fiber is identified as a figure of merit for building a narrow linewidth fiber Raman amplifier.
Abstract: Up to 4.8 W, ∼10 MHz, 1178 nm laser is obtained by Raman amplification of a distributed feedback diode laser in standard single mode fibers pumped by an 1120 nm Yb fiber laser. More than 10% efficiency and 27 dB amplification is achieved, limited by onset of stimulated Brillouin scattering. The ratio of Raman to Brillouin gain coefficient of a fiber is defined as a figure of merit for building a narrow linewidth fiber Raman amplifier.

Journal ArticleDOI
TL;DR: A configuration for linear cavity Brillouin fiber laser generation is demonstrated using a standard single-mode fiber, two optical circulators, a 3 dB coupler, and a 95/5 coupler to allow high efficiency.
Abstract: A configuration for linear cavity Brillouin fiber laser (BFL) generation is demonstrated using a standard single-mode fiber, two optical circulators, a 3 dB coupler, and a 95/5 coupler to allow high efficiency. With a Brillouin pump (BP) power of 13 dBm, the laser peak power is 12.3 dB higher than a conventional linear cavity BFL at an upshifted wavelength of 0.086 nm from the BP wavelength. In addition, it is revealed that the BFL peak power can be higher than the transmitted BP peak power when the BP power exceeds the second Brillouin Stokes threshold power.

Proceedings ArticleDOI
14 Apr 2008
TL;DR: In this article, a simple physical description of the nonlinear optical interaction based on Brillouin echoes is presented, which makes potentially possible distributed optical sensing down to centimeter spatial resolution.
Abstract: A simple physical description of the nonlinear optical interaction based on Brillouin echoes is presented. This technique makes potentially possible distributed Brillouin sensing down to centimeter spatial resolution while preserving the narrowband feature of the natural Brillouin gain spectrum. Experimental conditions for the generation of Brillouin echoes are described and demonstrations of distributed measurements using a 1 ns (10 cm) pulse are presented.

Journal ArticleDOI
TL;DR: In this paper, the inelastic light scattering of the acoustic vibration of spherical nanoparticles has been studied within a continuum approximation, extending the previous models, valid for small particles, to the case of particle sizes comparable with the wavelength of the light.
Abstract: The inelastic light scattering of the acoustic vibration of spherical nanoparticles has been studied within a continuum approximation, extending the previous models, valid for small particles, to the case of particle sizes comparable with the wavelength of the light. A mechanism appears, i.e. the polarizability modulation related to density changes, which is typical of Brillouin scattering and is negligible for small particles. Furthermore, the contribution of the polarizability modulation induced by the relative displacements of atoms, which produces the Raman scattering in small particles, strongly changes. Spheroidal modes other than the $l=0$ and $l=2$ ones, the only Raman active in small particles, contribute to both scattering mechanisms. As the size increases, higher $l$ modes with higher $n$, the index that labels the radial wave vector, become important. In relatively large particles, the active $(n,l,m)$ spheroidal modes are those with frequency close to that of the Brillouin active vibrations in the bulk material, i.e., ${\ensuremath{\omega}}^{nl}\ensuremath{\approx}q{v}_{L}$, where $\mathbf{q}$ is the exchanged wave vector of the light and ${v}_{L}$ is the longitudinal sound velocity. Also torsional modes become active and produce depolarized light scattering with properties similar to those of transverse acoustic phonons.

Journal ArticleDOI
TL;DR: In this article, the authors used optical fiber embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montreal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz.
Abstract: For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h−1), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montreal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m.

Journal ArticleDOI
TL;DR: In this article, a multi-wavelength laser is demonstrated using stimulated Brillouin scattering in a singlemode fiber with a feedback loop using two couplers and an optical circulator.
Abstract: A multi-wavelength laser is demonstrated using stimulated Brillouin scattering in a single-mode fiber with a feedback loop using two couplers and an optical circulator. This Brillouin fiber laser can operate at any wavelength depending on the Brillouin pump (BP) wavelength used. With a BP of 14 dBm, approximately 8 to 10 BFL lines are obtained in both forward and backward directions respectively with a line spacing of 0.16 nm. The use of the 99/1 coupler and 50/50 coupler gives the highest power and number of lines for the forward and backward outputs respectively. The maximum Stokes power obtained is approximately 8.0 dBm. The anti-Stokes lines are also obtained due to four wave mixing and bidirectional operation. The combination of forward and backward output can generate a larger number of lines with channel spacing of 0.08 nm.