mareev_2018#

E. Mareev, V. Aleshkevich, F. Potemkin, V. Bagratashvili, N. Minaev and V. Gordienko, Opt. Express 26, 13229 (2018)

Source record · Catalogue · Review register

Source kind: measurement

Recorded technique: Spectral broadening by self-phase modulation of 1240 nm Cr:forsterite pulses (200 fs in the set-up description, ‘150-fs laser pulse’ in the Fig. 5 caption; up to 2 mJ, 10 Hz, energy kept below filamentation) through an 11.6 cm stainless-steel supercritical-fluid cell with two 5 mm sapphire windows, at pressures up to 200 bar along isotherms (CO2 33.5 and 50 C; Xe 24 and 34 C); RMS spectral widths averaged over 20 pulses; n2 from the RMS broadening formula (Eq. 14) and the nonlinear phase (Eq. 9); the accuracy was ‘verified’ on a 5 mm fused-silica window with n2 = 2.8 +- 0.3 x 10^-20 m^2/W (their ref. 32).

Materials in structured entries: CO2, Xe

Dataset quantities: nonlinear_index

Contents: 2 datasets; 0 formulas.

Curation notes#

Defining equations. Theory (p. 4-5): n = 1 + N beta/3 + (4 pi N beta^2 / (45 k T)) E^2 = n0 + n2 E^2 (Eq. 1), n2 = 4 pi N beta^2/(45 k_B T) ~ N beta^2 (Eq. 2): a Langevin orientational model with the mean polarizability beta, used to motivate the cluster-driven rise of n2 near the Widom line; it is not a model of the electronic n2 (an isotropic atom has no orientational Kerr effect). Measurement (p. 6-7): phi_max = -L (w0/c) (n2/n0) I0 (Eq. 9; plus a fluctuating part) and Delta w_out/Delta w_in = (1 + (4/(3 sqrt 3)) phi_max^2)^2 (Eq. 14, as printed, for a transform-limited Gaussian pulse, from their ref. 31). The values are in m^2/W, so n2 multiplies the intensity (coefficient = self, SPM of one beam). No beam size or intensity is reported.

Values (Fig. 5 caption, p. 9, checked in the PDF text layer): ‘First bar corresponds to the n2 = 3.4 +- 0.6*10^-22 m2/W in CO2 and n2 = 6.2 +- 1.6*10^-22 m2/W in Xe at atmospheric pressure’ (the library’s markdown reads ‘m/W’ for CO2; the PDF has m2/W); ‘First bar’ is the 1 bar point of the pressure scans. The temperature is that of the isotherm, not stated for the 1 bar points: the lower isotherm is assumed (CO2 306.65 K, Xe 297.15 K). Maxima near the ridge (Widom line), supercritical states, not gas-phase values (abstract): 4.8 x 10^-20 m^2/W (CO2), 3.5 x 10^-20 m^2/W (Xe). Density slopes (p. 9): n2 ~ (0.9 +- 0.2) rho (CO2, 1-60 bar), (0.8 +- 0.2) rho (90-150 bar), (0.7 +- 0.2) rho (Xe, 0-45 bar), (0.4 +- 0.1) rho (70-90 bar), in ‘m5/(W*kg)’ with rho in kg/m^3: a factor of about 1e-22 is evidently missing (the 1 bar values over the densities, about 1.7 and 5.3 kg/m^3 with molar masses 44.01 and 131.29 g/mol and optmat’s densities, give 2.0e-22 and 1.2e-22 m^5/(W kg)). Not extracted.

Both 1 bar values are excluded: they are about ten times the established values. Xe: 6.2e-22 m^2/W against 5.8e-23 m^2/W at 800 nm (Wahlstrand et al. 2012b, quoted by pigeon_2018; the dispersion to 1240 nm lowers it by a few per cent), a factor 11; CO2: 3.4e-22 against Geints et al.’s 1.0e-23 (50 fs) and 5.4e-23 m^2/W (500 fs) at 800 nm (geints_2025), a factor 6 to 34 (rotation explains at most the long-pulse part). Why (an assessment; the paper gives no error budget beyond the silica check): (1) the two 5 mm sapphire windows. With the paper’s own fused-silica value as a stand-in for sapphire, the windows’ n2 L (2.8e-22 m) is about 40 times that of 11.6 cm of Xe at 1 bar (6.6e-24 m for n2 = 5.7e-23 m^2/W); the paper does not say how the window SPM was separated from the gas SPM, and an incomplete subtraction at 1 bar, where the gas adds about 2 % to the phase, inflates the gas value by a large factor. (2) The intensity I0 of Eq. (9) is not reported; an error in it scales n2 directly. (3) Eq. (14) as printed (an outer square) gives broadening 1 + (8/(3 sqrt 3)) phi^2 for small phi; any misprint in that exponent changes n2 by a factor of about 2, not 10. An earlier reading’s ‘about 10 times too high’ is confirmed for Xe; the cause cannot be settled from the paper.

Wavelength 1240 nm (medium not stated). Parts: Xe electronic; CO2 at 200 fs includes part of the rotational response (instantaneous).

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets#

mareev_2018/spm_1bar_CO2#

{
  "id": "spm_1bar_CO2",
  "material": "CO2",
  "table": "text",
  "quantity": "nonlinear_index",
  "unit": "m2/W",
  "scale": 1e-22,
  "abscissa_unit": "nm",
  "state": {
    "pressure_pa": 100000.0,
    "temperature_k": 306.65
  },
  "use": "excluded",
  "uncertainty": {
    "column": true,
    "level": "not stated"
  },
  "parameters": {
    "part": "instantaneous",
    "coefficient": "self",
    "pulse_fs": 200
  }
}

1 inline points in the source record.

Fig. 5 caption (p. 9): n2 = 3.4 +- 0.6 x 10^-22 m^2/W ‘at atmospheric pressure’ (1 bar point of the 33.5 C isotherm assumed). Excluded: 6 to 34 times Geints et al.’s 800 nm values; see the record’s notes for the likely causes.

mareev_2018/spm_1bar_Xe#

{
  "id": "spm_1bar_Xe",
  "material": "Xe",
  "table": "text",
  "quantity": "nonlinear_index",
  "unit": "m2/W",
  "scale": 1e-22,
  "abscissa_unit": "nm",
  "state": {
    "pressure_pa": 100000.0,
    "temperature_k": 297.15
  },
  "use": "excluded",
  "uncertainty": {
    "column": true,
    "level": "not stated"
  },
  "parameters": {
    "part": "electronic",
    "coefficient": "self",
    "pulse_fs": 200
  }
}

1 inline points in the source record.

Fig. 5 caption (p. 9): n2 = 6.2 +- 1.6 x 10^-22 m^2/W ‘at atmospheric pressure’ (1 bar point of the 24 C isotherm assumed). Excluded: about 11 times the established Xe value; see the record’s notes.

Formulas#

No formulas are recorded.

Corrections#

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.