Simultaneous position-resolved mapping of chromatic dispersion and Brillouin shift along single-mode optical fibers

We describe a new method for performing simultaneous position-resolved measurements of chromatic dispersion and Brillouin shift along single-mode optical fibers. The technique provides consistent high-resolution and low-noise results for both quantities. Our measurements indicate a certain correlation between both magnitudes, although the degree of correlation varies for the different manufacturers tested

Physical limits to broadening compensation in a linear slow light system

The dispersion experienced by a signal in a slow light system leads to a significant pulse broadening and sets a limit to the maximum delay actually achievable by the system. To overcome this limitation, a substantial research effort is currently being carried out, and successful strategies to reduce distortion in linear slow light systems have already been demonstrated. Recent theoretical and experimental works have even claimed the achievement of zero-broadening of pulses in these systems. In this work we obtain some physical limits to broadening compensation in linear slow light systems based on simple Fourier analysis. We show that gain and dispersion broadening can never compensate in such a system. Additionally, it is simply proven that all the linear slow light systems that introduce a low-pass filtering of the signal (a reduction in the signal root-mean- square spectral width), will always cause pulse broadening. These demonstrations are done using a rigorous shape-independent definition of pulse width (the root-mean-square temporal width) and arguments borrowed from time-frequency analysis

Spatially resolved measurement of chromatic dispersion and Brillouin shift along single-mode optical fibers

We present a new technique for simultaneous measurement of chromatic dispersion and Brillouin shift distribution along conventional, single-mode optical fibers used in telecommunications. It is based on performing Brillouin Optical Time Domain Analysis (BOTDA) over the four-wave mixing generated by two low-power pumps ( less than or equal 10 mW). Unlike others, this technique can measure any arbitrary value of dispersion. With the use of this technique we have obtained consistent, high-resolution and low-noise measurements for both magnitudes. Our measurements indicate a certain correlation between the spatial distribution of both quantities, although the degree of correlation varies for the different manufacturers tested

“Slow Light” in stimulated Brillouin scattering: on the influence of the spectral width of pump radiation on the group index: Comment

In a recent paper by Kovalev et al [Optics Express 17, 17317 (2009)] the coupled equations describing stimulated Brillouin scattering (SBS) were solved in the Fourier domain. The main conclusion driven by the authors was that SBS pump spectral broadening was not effective in increasing the interaction bandwidth. While the calculations are essentially correct, the interpretation of the results leads to erroneous conclusions

Development of a Mesoscale Finite Element Constitutive Model for Fiber Kinking

A mesoscale finite element material model is proposed to analyze structures that fail by the fiber kinking damage mode. To evaluate the assumptions of the mesoscale model, the results were compared with those of a high-fidelity micromechanical model. A direct comparison between the two models shows remarkable correlation, indicating that the key features of the fiber kinking phenomenon are appropriately accounted for in the mesoscale model. The mesoscale model is applied to structural analysis cases to demonstrate the capabilities of the model. A verification study is conducted with an unnotched compression specimen and preliminary validation is demonstrated with a notched compression specimen. The results show that the model is successful at representing the kinematics of fiber kinking while at the same time highlighting the need for further verification and validation

Distributed measurement of chromatic dispersion by four-wave mixing and Brillouin optical-time-domain analysis

A new nondestructive method for measuring the spatial distribution of chromatic dispersion along an optical fiber is presented. It is based on using Brillouin optical time-domain analysis to probe the power distribution of the four-wave mixing generated by two continuous-wave lasers. The results obtained prove that this new method is capable of providing better performance than comparable techniques. Furthermore, sensing the variations of Brillouin gain maximum produces additional information about the fiber, such as presence of strain and concentration of GeO2. © 2003 Optical Society of America

Self-Advanced Propagation of Light Pulse in an Optical Fiber Based on Brillouin Scattering

We propose a novel method to realize self-induced fast light and signal advancement with no distinct pump source in optical fibers, based on stimulated Brillouin scattering. This scheme will be helpful for real application systems

Self-advanced fast light propagation in an optical fiber based on Brillouin scattering

We experimentally demonstrate an extremely simple technique to achieve pulse advancements in optical fibers by using both spontaneous amplified and stimulated Brillouin scattering. It is shown that the group velocity of a light signal is all-optically controlled by its average power while it propagates through an optical fiber. The signal generates an intense back-propagating Stokes emission that causes a loss on the signal through depletion. This narrowband loss gives rise to a fast light propagation at the exact signal frequency. The Stokes emission self-adapts in real time to the Brillouin properties of the fiber and to a wide extent to the signal bandwidth

Modeling Fiber Kinking at the Microscale and Mesoscale

A computational micromechanics (CMM) model is employed to interrogate the assumptions of a recently developed mesoscale continuum damage mechanics (CDM) model for fiber kinking. The CMM model considers an individually discretized three dimensional fiber and surrounding matrix accounting for nonlinearity in the fiber, matrix plasticity, fiber/matrix interface debonding, and geometric nonlinearity. Key parameters of the CMM model were measured through experiments. In particular, a novel experimental technique to characterize the in situ longitudinal compressive strength of carbon fibers through indentation of micropillars is presented. The CDM model is formulated on the basis of Budiansky's fiber kinking theory (FKT) with a constitutive deformation-decomposition approach to alleviate mesh size sensitivity. In contrast to conventional mesoscale CDM models that prescribe a constitutive response directly, the response of the proposed model is an outcome of material nonlinearity and large rotations of the fiber direction following FKT. Comparison of the predictions from the CMM and CDM models shows remarkable correlation in strength, post-peak residual stress, and fiber rotation, with less than 10% difference between the two models in most cases. Additional comparisons are made with several fiber kinking models proposed in the literature to highlight the efficacy of the two models. Finally, the CMM model is exercised in parametric studies to explore opportunities to improve the longitudinal compression strength of a ply through the use of nonconventional microstructures

Zero-gain slow and fast light propagation in an optical fiber

Slow and fast light with null amplification or loss of a light signal is experimentally demonstrated. This novel method for producing zero-gain slow and fast light takes advantage of the great flexibility of stimulated Brillouin scattering in optical fibers to generate synthesized gain spectra. Generation of optical delays and advancements with minor amplitude change is realized through the superposition of gain and loss profiles showing very different spectral widths, resulting in a synthesized spectral profile identical to an ideal electromagnetically-induced transparency. © 2006 Optical Society of America