Suppression of plasma contribution in femtosecond degenerate four‐wave mixing (fs‐DFWM) at high intensity

We study theoretically strong field effects in rotational femtosecond degenerate four-wave-mixing (DFWM). First, we developed a perturbative approach and calculated the leading correction to the standard (weak field) formula for femtosecond DFWM signal. Second, we constructed a nonperturbative approach for computing femtosecond DFWM signals excited by (short) pulses of arbitrary intensity. Third, we worked out the theory to describe femtosecond DFWM with an extra aligning pulse. We show that the strong-pulse-induced nonadiabatic alignment does explain many experimentally detected features that develop in femtosecond DFWM signals with increasing laser intensity beyond the standard weak field regime. However, we also show that this nonadiabatic alignment cannot solely be responsible for the onset of the heterodyne detection and pronounced constant background in DFWM signals excited by high intensity laser pulses.

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“…The background has repeatedly been detected experimentally. 8,[12][13][14][15][16][17][18][19][20] To describe it, a formula…”

Section: Perturbative Approachmentioning

confidence: 99%

“…[9][10][11] To improve the signal-to-noise, rather strong laser pulses are frequently used, so that the standard ͑weak field͒ theory is no longer applicable. Furthermore, strong pulses cause several interesting features in femtosecond DFWM signals, 8,[12][13][14][15][16][17][18][19][20] which are not entirely understood yet.…”

Section: Introductionmentioning

confidence: 99%

Strong field effects in rotational femtosecond degenerate four-wave mixing

Gelin

Riehn²,

Kunitski³

et al. 2010

The Journal of Chemical Physics

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“…The effect of higher electronic surfaces in H 2 and the control of the shapes of vibrational wave packets were discussed. Femtosecond degenerate fourwave mixing (DFWM) experiments in CO 2 at high intensity were performed by Rouzée et al 71 A strong background due to plasma formation was observed in these samples. The authors showed that the plasma contribution can be avoided by employing perpendicular polarizations for the two pump pulses.…”

Section: Other Nonlinear Techniquesmentioning

confidence: 99%

Recent advances in linear and nonlinear Raman spectroscopy II

Kiefer

2008

J Raman Spectroscopy

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Following the first review on recent advances in linear and nonlinear Raman spectroscopy, the present review summarizes papers mainly published in the Journal of Raman Spectroscopy during 2007. This serves to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal.

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“…[11] CARS spectroscopy has been performed via single-beam [12,13] coherently engineered by spatial light modulation, optimal control [14] and tunable supercontinuum source from photonic-crystal fibers. [15,16] Recently, CARS is also used to study molecules in background plasmas [17] and terahertz regime, [18] simultaneous detection of multi-species gas [19] , determination of temperature [20] and collision induced dephasing and rotational energy transfer. [21] Good reviews on the fundamentals, developments and applications of CARS technique were given by Kiefer [22] and Zheltikov.…”

Section: Introductionmentioning

confidence: 99%

Theory of coherent anti‐Stokes Raman scattering for mesoscopic particle with complex molecules: angular‐dependent spectrum

Ooi

2009

J Raman Spectroscopy

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We present a microscopic theory of nonlinear scattering of mesoscopic particle that may be composed of complex molecules. We predict that the spectrum of the scattered field depends on the angle of observation. Transform theory is used to compute the third-order susceptibility for coherent anti-Stokes Raman scattering (CARS) of molecules with known absorption spectrum and vibrational modes. By incorporating the theory into an integral scattering formula, we develop a rigorous theory which leads to powerful numerical experimentation of nonlinear optical process in mesoscopic systems composed of complex molecules and driven by laser pulses with arbitrary shape and spectral content. We obtain an expression for spectral dependent CARS field which includes multiple internal reflection and refraction of the incident fields via Mie theory. The theory is used to study the variations of the CARS spectra and intensity on laser parameters and direction of detection. High-resolution spectra computed for hybrid CARS scheme shows that the relative intensities of the characteristic peaks in the CARS spectrum depend on the direction of detection. This effect can be explained by the interference between the linear response (absorption and dispersion) and the four-wave mixing process in the mesoscopic medium. The theory is useful for nonlinear spectroscopy, microscopy and nanophotonics involving small particles.

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Suppression of plasma contribution in femtosecond degenerate four‐wave mixing (fs‐DFWM) at high intensity

Cited by 10 publications

References 14 publications

Strong field effects in rotational femtosecond degenerate four-wave mixing

Strong field effects in rotational femtosecond degenerate four-wave mixing

Recent advances in linear and nonlinear Raman spectroscopy II

Theory of coherent anti‐Stokes Raman scattering for mesoscopic particle with complex molecules: angular‐dependent spectrum

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