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Grün, J. B.; McQuillan, A. K.; Stoicheff, B. P.

doi:10.1103/physrev.180.61

Cited by 92 publications

(6 citation statements)

References 28 publications

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“…We study how laser detuning and decoherence time of the atomic spin wave affect the onset threshold. We find that the onset of the Raman oscillation is not due to optical feedback, as commonly believed [3,5,31,32], but is from the coherent buildup of the atomic spin wave. Therefore there is no need for optical feedback.…”

Section: Introductionsupporting

confidence: 57%

“…Theoretical descriptions [2] basically provided only some gain mechanisms and attributed the observed sharp onset of the coherent Raman oscillation to the optical feedback due to Rayleigh scattering of the Raman fields or diffusive reflection of the window of sample cells [3], similar to the mechanism of the laser's operation. More complicated selffocusing theory is successful in some cases [4].…”

Section: Introductionmentioning

confidence: 99%

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Mirrorless parametric oscillation in an atomic Raman process

et al. 2014

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We investigate experimentally and theoretically the onset of parametric oscillation in a single-pass atomic Raman scattering process without the optical feedback. We find that this Raman oscillation effect is due to the coherent buildup of the atomic spin waves, and therefore the threshold of the Raman pump power for the onset of the oscillation depends on the decoherence time of the atomic spin waves and the Raman coupling constant but is not sensitive to the loss of the Stokes field, unlike the effect of amplified spontaneous emission. A simple theory of atomic Raman process fits the experimental results very well. The long decoherence time of the atomic spin waves in the atomic Raman process leads to a threshold power as low as a few hundred microwatts.

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Section: Introductionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Mirrorless parametric oscillation in an atomic Raman process

et al. 2014

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“…The combined effects of self-focusing and beam diffraction result in filament formation [1][2][3][4][5][9][10][11][12]. The self-focusing increases the pulse intensity enormously and enhances all nonlinear optical effects [13][14][15][16][17][18][19]. The abrupt rise of nonlinear optical effects is an indication of self-focusing and may be used to determine the self-focusing length.…”

Section: Pacsmentioning

confidence: 99%

Determination of nonlinear refractive indices by external self-focusing

Meier

Penzkofer

1989

Appl. Phys. B

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The nonlinear refractive index of benzene is determined by measuring the reduction of the beam divergence of picosecond ruby laser pulses when passing through a benzene sample. Time-integrated spatial beam profiles give an effective refractive index while time-resolved beam profiles measured with a streak camera allow the determination of the temporal evolution of the nonlinear refractive index. PACS:42.65, 42.65.J At high laser powers the refractive index of materials becomes intensity dependent. The spatial laser beam profile causes a spatial refractive index profile and leads to self-focusing [1][2][3][4][5][6]. The overall beam profile is responsible for whole-beam self-focusing while an intensity modulation of the spatial intensity distribution leads to a beam break-up (small-scale selffocusing) [5][6][7][8]. The combined effects of self-focusing and beam diffraction result in filament formation [1][2][3][4][5][9][10][11][12]. The self-focusing increases the pulse intensity enormously and enhances all nonlinear optical effects [13][14][15][16][17][18][19]. The abrupt rise of nonlinear optical effects is an indication of self-focusing and may be used to determine the self-focusing length. The determination of the nonlinear refractive index from the abrupt rise of nonlinear optical effects is complicated by the fact that either whole-scale self-focusing or small-scale selffocusing may act and the small-scale self-focusing parameters (ripple widths and modulation depths) are difficult to determine.The vagueness of whole-scale or small-scale selffocusing dynamics may be avoided by changing from internal self-focusing (focal point caused by nonlinear refractive index is inside sample) to external selffocusing (focal point is outside sample) [1 ]. In this case the nonlinear refractive index of the sample causes a reduction of the overall beam divergence and the effects of small ripples across the beam profile may be neglected.In our experiments we determine the reduction of beam divergence by comparing the beam diameters (FWHM) of two pulses at a certain distance behind the sample position, where one pulse passes through the sample and the other pulse is bypassed. Our timeresolved measurements of the beam diameters with a streak camera and a two dimensional readout system allow the study of the instantaneous and transient contributions to the nonlinear refractive index [12,18,20]. The effective time-averaged and the time-resolved nonlinear refractive index of benzene are measured with picosecond light pulses of a ruby laser. The reported time-averaged nonlinear refractive index coefficients n 2 of benzene vary by a factor of ten in the region between n 2 = 1.4x 10~2 1 m 2 V~2 and lxlO" 20 m 2 V-2

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“…Stimulated Raman scattering of CS 2 has been observed for high intensity laser excitation, 50,51 and should grow exponentially from the spontaneous Raman scattering. The gain is proportional to the product of the total differential cross section, the number of molecules, and the term (⌬) Ϫ1…”

Section: Figures 2͑a͒ and 2͑b͒mentioning

confidence: 99%

Raman resonance de-enhancement in the excitation profile of CS2

Ray

Sedlacek

1998

The Journal of Chemical Physics

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Enhancement and de-enhancement effects in vibrational resonance Raman optical activity J. Chem. Phys. 132, 044113 (2010); 10.1063/1.3300069Comparison of the resonance-enhanced multiphoton ionization spectra of pyrrole and 2,5-dimethylpyrrole: Building toward an understanding of the electronic structure and photochemistry of porphyrinsThe total differential Raman cross section of the symmetric vibrational mode of CS 2 (652 cm Ϫ1 ) in liquid phase has been measured as a function of excitation wavelength from the visible to the ultraviolet. The resulting excitation profile shows a strong preresonance enhancement when the excitation wavelength is less than 300 nm. The cross section measured at 240 nm is about three orders-of-magnitude larger than the 4 dependence for Raman scattering. The observed preresonant effect appears to be dominated by the 1 B 2 ( 1 ⌺ u ϩ )← 1 ⌺ g ϩ transition. A minimum in the excitation profile occurs at a wavelength that is associated with the peak of the near-UV absorption band (ϳ320 nm). The observed dip in the profile is ascribable to a quantum interference between the 1 B 2 ( 1 ⌺ u ϩ ) and the two Renner-Teller components, 1 B 2 and 1 A 2 ( 1 ⌬ u ). The transition from the ground state to the lower electronic state is electronically forbidden, but it becomes vibronically allowed due to the Renner-Teller interaction. This may be the first observation of Raman resonance de-enhancement due to the interference involving three excited states.

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Intensity and Gain Measurements on the Stimulated Raman Emission in LiquidO2andN2

Cited by 92 publications

References 28 publications

Mirrorless parametric oscillation in an atomic Raman process

Mirrorless parametric oscillation in an atomic Raman process

Determination of nonlinear refractive indices by external self-focusing

Raman resonance de-enhancement in the excitation profile of CS2

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