Model analysis of the Raman spectrum from fused silica optical fibers

Walrafen, G. E.; Krishnan, P. N.

doi:10.1364/ao.21.000359

Cited by 48 publications

(27 citation statements)

References 11 publications

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“…Indeed, the intensity of Raman scattering from the silica optical fibers was significantly decreased. It is possible to note in these spectra that the optical signal extends to 1100 cm −1 , and it consists of a number of broadened lines, which corresponds to different types of glass lattice vibrations of the quartz [17]. Figure 4 presents two spectra that permit to compare the effect of the presence of the optical filter in the catheter in contact with a sample of naphthalene.…”

Section: Resultsmentioning

confidence: 99%

Catheter with dielectric optical filter deposited upon the fiber optic end for Ramanin vivobiospectroscopy applications

et al. 2008

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Abstract. Raman spectroscopy (RS) is a powerful tool that allows obtaining significant biochemical information from biological tissue. The fiber optic catheter permits applications in vivo that present wide clinical employment. This biochemical analysis is developed through a guide light that furnishes to Raman spectroscopy system the data obtained from tissue. These Raman signals represent the modes of vibration of molecular groups that are present in the biological molecules. Raman measurements undergo the optical influence of the material that constitutes the catheter, mainly Raman scattering of the silica that composes the fiber optic, decreasing signal to noise ratio (SNR) of the resultant spectra. In this work, a dielectric optical filter called "bandpass" was deposited upon the surface of the tip of the central fiber optic (distal probe). Indeed, other six fibers without any optical filter are disposed around this central optical fiber with "bandpass". This prototype of catheter presented significant decrease of the silica Raman scattering when compared with unfiltered catheters. The biomedical applications of this new catheter are auspicious, involving biochemical analysis and diagnosis in vivo, since the SNR improvement obtained propitiates a much more informative Raman spectrum.

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Section: Resultsmentioning

confidence: 99%

Catheter with dielectric optical filter deposited upon the fiber optic end for Ramanin vivobiospectroscopy applications

et al. 2008

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“…Such a modeling, provided in [35] and [36], has shown that it is necessary to combine an ensemble of damped oscillators to get an accurate fit to the response function. In this intermediate broadening model, which involves neither homogeneously nor inhomogeneously broadened oscillators, the Raman response is modeled as an ensemble of 13 damped harmonic oscillators with a Gaussian distribution of the mean frequencies.…”

Section: Response Timementioning

confidence: 99%

Analyzing the fundamental properties of Raman amplification in optical fibers

Rottwitt

Povlsen

2005

J. Lightwave Technol.

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Abstract-The Raman response of germanosilicate fibers is presented. This includes not only the material dependence but also the relation between the spatial-mode profile of the light and the Raman response in the time and frequency domain. From the Raman-gain spectrum, information is derived related to the nonlinear refractive index due to nuclear motions and the Raman response function in the time domain. It is demonstrated that the Raman-gain coefficient may be reduced up to 60% if the signal propagates in the fundamental mode while the pump alternates between the fundamental mode and a higher order mode. A simple model shows that the time response related to the decay of phonons is significantly larger in germanate glass relative to silica glass. From the Raman gain, it is found that the contribution to the nonlinear refractive index from nuclear motions is reduced by a factor of 2 in germanate relative to silica glass.

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“…Firstly spectroscopic classification, multiple modes decomposition and interpretation of the experimental spontaneous Raman Stokes spectra were made in [6]. After development of the Raman gain spectrum from experimental spontaneous Raman spectrum [7,8], it was proposed [9] multiple modes decomposition of the Raman gain profile based on intermediate broadening model.…”

Section: Introductionmentioning

confidence: 99%

<title>Spectroscopic multiple-vibrational modeling of Raman gain in FRA</title>

Felinskyi¹

2008

SPIE Proceedings

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Fiber Raman amplifiers with the theoretical limit of gain bandwidth up to 12 THz are becoming more and more essential in wavelength-division-multiplexing optical communication systems with terabit capacity. In this work, the new spectroscopic model for the Raman gain spectrum decomposition in arbitrary optical fiber using multiple vibrational modes is presented. Modeling results is given for the development of stimulated Raman gain spectrum in silica fiber. Nonlinear fitting procedure with Levenberg-Marquardt method of Raman gain profile was applied and it gives practically exact approximation of the observed Raman gain spectrum in silica fiber. The integrated intensities of model spectra are coincided with experimental spectrum within <0.3%. The optimal set of Raman gain parameters is compiled to simple analytical expressions that can be integrated and differentiated in symbolic form and are easy to evaluate numerically. Modeling results on the set of basic Raman amplifier characteristics such us: gain ripple, bandwidth, group delay, and noise performance is presented. Model is applicable to FRA design in fiber materials with known SRS spectra of any complexity.

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Model analysis of the Raman spectrum from fused silica optical fibers

Cited by 48 publications

References 11 publications

Catheter with dielectric optical filter deposited upon the fiber optic end for Ramanin vivobiospectroscopy applications

Catheter with dielectric optical filter deposited upon the fiber optic end for Ramanin vivobiospectroscopy applications

Analyzing the fundamental properties of Raman amplification in optical fibers

<title>Spectroscopic multiple-vibrational modeling of Raman gain in FRA</title>

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