Rotational CARS generation through a multiple four-color interaction

Aldén, Marcus; Bengtsson, Per-Erik; Edner, Hans

doi:10.1364/ao.25.004493

Cited by 114 publications

(35 citation statements)

References 27 publications

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“…1 5-17 In one of these approaches (rotational dual-broadband CARS) the noise obtained in non~Raman resonant spectra was a factor of 2 lower than with a conventional CARS setup. 17 Current~ ly the optimum configuration of a CARS thermometry setup is an open question. Comparisons of the experimental char~ acteristics of CARS spectra recorded using a multimode or a single-mode pump laser have been performed for the conventional CARS setup.…”

Section: Introductionmentioning

confidence: 99%

Influence of laser-mode statistics on noise in nonlinear-optical processes—application to single-shot broadband coherent anti-Stokes Raman scattering thermometry

Kröll¹,

Sandell

1988

J. Opt. Soc. Am. B

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A quantitative approach for calculating the noise due to the stochastic nature of multimode laser radiation in nonlinear-optical processes is presented. The model is applicable when it is appropriate to describe the nonlinear interaction with a perturbation expansion in the incoming field, and it is derived under the assumption of independent individual laser-mode intensities and phases. It is possible to separate noise contributions from mode-amplitude and -phase fluctuations, respectively, and also to identify the noise contribution from each laser source. For coherent anti-Stokes Raman scattering (CARS) thermometry, the model shows that with a singlemode pump laser the stochastic phases in the dye laser do not generate noise in the conventional approach and that amplitude fluctuations in the dye laser(s) do not (significantly) generate noise in the dual-broadband approaches. Thus, in the dual-broadband approaches, the spectral noise in the Stokes beam is not a lower limit for the noise in the CARS beam. The model seems to overestimate the noise due to phase fluctuations and to underestimate the noise due to amplitude fluctuations.

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Section: Introductionmentioning

confidence: 99%

Influence of laser-mode statistics on noise in nonlinear-optical processes—application to single-shot broadband coherent anti-Stokes Raman scattering thermometry

Kröll¹,

Sandell

1988

J. Opt. Soc. Am. B

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“…In order to overcome this problem and increase the quality of single-shot spectral line contours, we applied a dual-broadband 8,9 (DBB) CARS configuration. This approach reduces the spectral noise in the CARS lineshape obtained during a single laser shot by averaging over the spectrum of driving force (Raman pumps spectra convolution) resulting from the interaction of two broadband pump dye laser sources with Raman transition.…”

Section: Methodsmentioning

confidence: 99%

Single‐shot high‐resolution dual‐broadband CARS interferometric lineshape spectroscopy

Vereschagin

Смирнов

Stelmakh

et al. 2005

J Raman Spectroscopy

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A high-resolution spectroscopic method that allows single-shot spectra of Raman-active molecular transitions in non-stationary media to be obtained with a resolution of ∼0.1 cm −1 was developed. The method is based on application of a Fabry-Pérot interferometer to spectral analysis of the CARS signal from Raman transitions with further detection of an interference pattern by a two-dimensional photo-matrix. The implementation of a dual-broadband (DBB) CARS configuration for effective spectral averaging over pump and Stokes laser spectra together with angular averaging of CARS intensities along the complete circumference of Fabry-Pérot interference patterns leads to a significant improvement of interferogram quality, so that nearly all of the single-shot interference patterns obtained for Q-branch lines of the hydrogen molecule in a gas probe volume became suitable for linewidth measurements.

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“…ω 4 D ω 1 ω 2 C ω 3 . In rotational CARS, using the dualbroadband rotational CARS approach 14,15 as in the present work, the rotational Raman resonances are excited by ω 1 and ω 2 from one broadband laser, whereas ω 3 is generated by a narrowband laser. Dual-broadband rotational CARS has been shown to be superior to single-broadband rotational CARS both from an experimental point of view and regarding the precision of the technique.…”

Section: Theorymentioning

confidence: 99%

Improved species concentration measurements using a species‐specific weighting procedure on rotational CARS spectra

Vestin

Afzelius

Bengtsson

2005

J Raman Spectroscopy

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Rotational coherent anti-Stokes Raman spectroscopy (CARS) is used for measurements of temperaturesand relative species concentrations. The evaluation of a rotational CARS spectrum is normally performed using a least-squares fitting algorithm to find the best-fit theoretical spectrum in a library of spectra calculated at different temperatures and relative concentrations. A general problem is that species with weak spectral features have a minor influence on the results in the standard evaluation procedure. A species-specific weighting (SSW) procedure enhancing the influence of weak spectral features in the spectral fitting algorithm has therefore been developed. The SSW procedure was tested on the evaluation of low concentrations of O 2 in mixtures with N 2 , and it is shown that both the accuracy and precision of single-shot spectra concentration measurements are improved by use of the SSW evaluation procedure. Also, a comparison with previously used weighting procedures shows that this approach is superior. The application of the technique to oxygen concentration measurements in the product gas of a fuel-lean flame is demonstrated. In addition, a test was made using the developed weighting procedure for thermometry, by applying spectral weighting to the rotational spectrum originating from the first thermally excited vibrational state. The precision of the temperature measurements was then slightly improved.

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Rotational CARS generation through a multiple four-color interaction

Cited by 114 publications

References 27 publications

Influence of laser-mode statistics on noise in nonlinear-optical processes—application to single-shot broadband coherent anti-Stokes Raman scattering thermometry

Influence of laser-mode statistics on noise in nonlinear-optical processes—application to single-shot broadband coherent anti-Stokes Raman scattering thermometry

Single‐shot high‐resolution dual‐broadband CARS interferometric lineshape spectroscopy

Improved species concentration measurements using a species‐specific weighting procedure on rotational CARS spectra

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