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1.
2.
Stimulated Brillouin scattering-induced phase noise in an interferometric fiber sensing system
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Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. The localized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber. The phase noise structure is analyzed for an interferometric fiber sensing system, and an unbalanced Michelson interferometer with an optical path difference of 1 m, as well as the phase-generated carrier technique, is used to measure the phase noise. It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold, increases dramatically at first and then gradually becomes flat when the input power is above the threshold, which is similar to the variation in relative intensity noise. It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering, which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering. 相似文献
3.
A first time O band Brillouin fiber laser is demonstrated and compared with the C band Brillouin fiber laser. By utilizing
a 20 km True wave fiber (TWF), the experiment demonstrated four Brillouin lines generated from the simple set-up of Brillouin
fiber laser. We compared the threshold between the Brillouin pump wavelength at 1310 nm which represent O band region and
1550 nm for C band region. It shows that the Brillouin threshold at O band region is smaller that C band. The channels spacing
between these two bands are also different, where O band have 12.72 GHz spacing while 1550 nm have 10.25 GHz spacing. 相似文献
4.
具体给出了含可饱和吸收体的单模驻波激光系统的哈密顿(Hamiltonian)量和序参量运动方程,并对序参量的定态解做了线性稳定性分析。结果表明,驻波系统在阈值附近的定态行为(非平衡相变行为、双稳行为、临界点附近的指数行为等)与行波系统定性类似,但具体细节有异。特别不同于行波的是,驻波情形下三个定态解中的I_分支有可能实现。 相似文献
5.
We experimentally demonstrate a multiwavelength Brillouin-erbium fiber laser in two configurations; uni-directional and bi-directional propagation of Brillouin pump and Brillouin Stokes signals through an Erbium-doped fiber gain. The influence of these configurations on the performance of the output parameters in terms of lasing threshold, output channel generation and tuning range of the generated output channels are investigated. We discovered that there is a trade-off between these two fiber laser configurations. The uni-directional amplifier configuration provides greater tuning range of 46.8 nm against 23 nm at maximum Brillouin pump power of 2 mW and 1480-nm pump power of 130 mW. On the other hand, the bi-directional amplifier configuration provides 13 output channels against 6 output channels obtained from the uni-directional amplifier configuration at the same pumping powers. Nevertheless, the bi-directional amplifier configuration requires much lower pump power to initiate lasing. 相似文献
6.
提出了一种新型的由熔石英棒和石英光纤组成的复合型相位共轭镜,其可运用于高重复频率激光输入系统中以改善光束质量.该复合相位共轭镜具有较高的受激布里渊散射反射率和受激布里渊散射损伤阈值以及较低的受激布里渊散射阈值等优点.实验中,在100 Hz重复频率下,最大获得了42.05%的受激布里渊散射反射率.根据实验条件,由耦合波方程及边界条件得到的物理模型,经数值求解后得到的结果和实验符合较好.且由理论结果提出了一种提高该复合型相位共轭镜工作状态的有效方法.
关键词:
复合型相位共轭镜
受激布里渊散射
熔石英
耦合波方程 相似文献
7.
SBS mirrors for XeCl lasers with a broad spectrum 总被引:2,自引:0,他引:2
H. J. Eichler R. König H. -J. Pätzold J. Schwartz 《Applied physics. B, Lasers and optics》1995,61(1):73-80
The stimulated Brillouin scattering threshold of focused broad-band XeCl laser radiation depends on the ratio of the coherence length to the Rayleigh range, which is affected by the transverse beam quality. With reduction of the focal length, the threshold decreases first and then reaches a nearly constant value. In addition, the energy reflectivity is increased. On the other hand, pulse shortening occurs and the phase conjugation fidelity is decreased. Separation of single lines from the structured XeCl laser spectrum improves the SBS efficiency. 相似文献
8.
Stimulated Brillouin scattering-induced phase noise in an interferometric fiber sensing system
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Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems.The localized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber.The phase noise structure is analyzed for an interferometric fiber sensing system,and an unbalanced Michelson interferometer with an optical path difference of 1 m,as well as the phase-generated carrier technique,is used to measure the phase noise.It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold,increases dramatically at first and then gradually becomes flat when the input power is above the threshold,which is similar to the variation in relative intensity noise.It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering,which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering. 相似文献
9.
M. Singh A. Sangwan S. Redhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(3):403-410
Optical phase conjugation via stimulated Brillouin scattering (OPC-SBS) in magnetized diffusion driven semiconductors under
the off-resonant transition regime has been investigated theoretically. The model is based upon the coupled-mode approach
and
incorporates the effect of pump absorption through the first-order induced polarization. The linear dispersion is found not
to
affect the reflectivity of the phase conjugate Stokes shifted Brillouin mode. The reflectivity of the image radiation is dependent
upon the Brillouin susceptibility and can be significantly enhanced through n-type doping of the crystal and the simultaneous
application of magnetic field. Moreover, the threshold of the pump intensity required for the occurrence of SBS in the crystal
with finite optical attenuation can be considerably diminished through a suitable choice of the excess carrier concentration
and
the magnetic field. Consequently, OPC-SBS becomes a possible tool in phase-conjugate optics even under not-too-high power
laser
excitation by using moderately doped n-type semiconductors kept under the influence of magnetic field. Numerical estimates
made
for n-InSb crystal at 77 K duly irradiated by nanosecond pulsed 10.6 μm CO2 laser show that high OPC-SBS reflectivity
(70%) can be achieved at pump intensities below the optical damage threshold if the crystal is used as an optical waveguide
with
relatively large interaction length (L ∼5 mm) which proves its potential in practical applications such as fabrication of
phase
conjugate mirrors. 相似文献
10.
A XeCl laser system without dispersive elements is used to investigate near threshold reflectivity and phase-conjugation (PC) fidelity of stimulated Brillouin scattering (SBS) mirrors with SF6 as the active medium. Using different focal-length lenses to focus the broadband laser radiation into the Brillouin medium, it was found that at threshold the effective interaction length for SBS is equal to the confocal parameter and that the SBS gain is equal to its steady-state value for monochromatic pumping. High PC-fidelity values ranging from 0.8–1.0 were found under most of the experimental conditions investigated. 相似文献
11.
S. Ghosh Nishchhal Yadav 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(2):173-178
Using the hydrodynamical model and following the coupled mode approach, detailed analytical investigation of stimulated Brillouin
scattering is performed in an electrostrictive semiconductor. The total induced current density including diffusion current
density and the effective Brillouin susceptibility are obtained under off-resonant laser irradiation. The analysis deals with
the qualitative behaviour of the Brillouin gain and transmitted intensity with respect to excess doping concentration and
magnetic field. Efforts are directed towards optimizing the doping level and magnetic field to achieve maximum Brillouin gain
at pump intensities far below the optical damage threshold level. It is found that by immersing a moderately doped semiconductor
in a sufficiently strong magnetic field in transverse direction, one can achieve resonant enhancement of Brillouin gain provided
the generated acoustic mode lies in the dispersionless regime. 相似文献
12.
We present experimental data on mass removal during 1064-nm pulsed laser ablation of graphite, niobium and YBa2Cu3O7-δ superconductor. Evidence for the transition from normal vaporization to phase explosion has been obtained for these materials,
showing a dramatic increase in the ablation rate at the threshold fluences of 22, 15 and 17.5 J/cm2, respectively. A numerical model is used to evaluate the ablation rate and temperature distribution within the targets under
near-threshold ablation conditions. The results are analyzed from the viewpoint of the vaporized matter approaching the critical
point with increasing laser fluence. A possible means of the estimating the thermodynamic critical temperature from the data
for nanosecond laser ablation is discussed. It is suggested that the critical temperature of refractory metals is higher than
that estimated with the traditional methods due to plasma effects. An analogy with the boiling crisis (the transition from
nucleate to film boiling) is drawn to explain the formation of ablation craters with spallated edges.
Received: 18 May 2000 / Accepted: 14 July 2000 / Published online: 22 November 2000 相似文献
13.
14.
Temporally stable high-fidelity optical phase conjugation by stimulated Brillouin scattering of cw laser radiation is achieved in multimode silica fiber with cavity feedback. A power threshold of approximately 500 mW and a reflectivity of 70% were obtained in a 340-m-long fiber with a cw Nd:YAG laser. 相似文献
15.
A photonic crystal fibre Brillouin laser based on fibre Bragg grating Fabr-Perot cavity is presented. A highly nonlinear photonic crystal fibre 25 m in length is used as Brillouin gain medium and fibre Bragg grating Fabry-Perot cavity is chosen in order to enhance the laser conversion efficiency and suppress the higher-order Stokes waves. The laser reaches the threshold at input power of 35 mW, and the experimental laser conversion efficiency achieves 18% of the input power of 140 mW and does not show higher-order Stokes waves. A photonic crystal fibre Brillouin laser with shorter fibre length and lower threshold is experimentally realized. 相似文献
16.
Da-he Liu Jin-wei Shi Xu-dong Chen Min Ouyang Wen-ping Gong 《Frontiers of Physics in China》2010,5(1):82-106
The principle of a lidar based on Brillouin scattering is introduced. The basic physics of the Brillouin lidar is discussed.
The applications of the Brillouin lidar in remote sensing of the ocean, such as measurement of the sound speed and the bulk
viscosity of water and detecting submerged objects are investigated. An actual Brillouin lidar system is developed. Also,
several basic problems related to Brillouin lidar are studied in detail. The attenuation coefficient of a pulsed laser beam
with high pulsed energy in water is investigated; it is helpful to reveal the propagation property of a laser beam in water.
The investigations on the threshold value of SBS are made theoretically and experimentally. Finally, a novel phenomena is
investigated experimentally, in which Stimulated Raman scattering can be enhanced by stimulated Brillouin scattering. 相似文献
17.
A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber. The laser exhibits a 3.6-mW threshold. The output power is 22 mW with 40-mW pump power, and the maximum optical-to-optical efficiency is 5570. The output is single wavelength with a 3-dB linewidth of 5 MHz, and the interval of center frequency between the laser and the pump light is 11 GHz (0.088 nm). It is shown that the stimulated Brillouin scattering threshold of ring resonator is lower and the energy transfer efficiency is higher than those in fiber. 相似文献
18.
Yu. F. Markov E. M. Roginskii 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(8):1008-1011
Bragg and diffuse X-ray reflections from the M points of the Brillouin zone boundary of a benzil crystal paraphrase, the integral intensity of which is associated with the order parameter and its fluctuations, are studied. Original data on the temperature behavior of the order parameter and diffuse scattering are obtained. The relevant critical exponents are determined. A conclusion is drawn as to the proximity of the phase transition in these crystals to the tricritical point. A phase transition model is discussed. 相似文献
19.
M. Goul’kov O. Shinkarenko S. Odoulov E. Krätzig R. Pankrath 《Applied physics. B, Lasers and optics》2001,72(2):187-190
The threshold behavior is studied for a ring-loop coherent oscillator with a photorefractive strontium barium niobate (SBN)
sample. A soft onset of oscillation is revealed and critical slowing down is observed in the temporal development of light-induced
scattering below the threshold, thus pointing to a similarity with a second-order phase transition.
Received: 10 July 2000 / Published online: 20 September 2000 相似文献
20.
The correlation functions of the intensity fluctuations are calculated by use of a linearization procedure for the equations of motion which include the coupling of the counter-rotating travelling waves of the ring laser in the cases of Doppler broadening, of homogeneous broadening with a self-induced population-inversion grating, and in intermediate cases. Depending on the strength of the mode competition various stable stationary solutions exist for the amplitudes. The transition between these stable states shows phenomena closely resembling phase transitions such as critical fluctuations, critical slowing down, etc. In particular, when the system passes from the state where both modes are above threshold to the state where one mode is below threshold, the negative cross-correlation of the fluctuations also becomes critical. In the case of the transient behaviour of the ring laser in the unstable region the time development of the amplitudes and the correlation functions are described in a short-time approximation. 相似文献