geints_2025#
Yu. E. Geints, V. O. Kompanets and S. V. Chekalin, Opt. Commun. 596, 132584 (2025)
Source record · Catalogue · Review register
DOI: 10.1016/j.optcom.2025.132584
Source kind: measurement
Recorded technique: Self-focusing distance of collimated (4 mm) 800 nm Ti:sapphire pulses (45 fs, 48 fs after the entrance window, taken as 50 fs; chirped to 100-500 fs with the compressor; up to 3 mJ, about 60 GW; 20 Hz) in a 315 cm polycarbonate cell of Ar, N2 or CO2 (99.995 %) at 1-11 bar; the filament start z_SF located with a movable screen from the plasma spot and the onset of supercontinuum; n2 from Marburger’s law z_SF ~ (P0/P_c)^-k with k = 0.5 and P_c = 3.79 lambda^2 / (8 pi n0 n2), relative to a reference.
Materials in structured entries: Ar, CO2, N2
Dataset quantities: nonlinear_index
Contents: 7 datasets; 0 formulas.
Curation notes#
Defining equations (p. 2-3). n(E) = n0 + n2 |E|^2 (p. 2; the values are in m^2/W, so |E|^2 is the intensity: coefficient = self, the single-beam index of self-focusing). P_c = 3.79 lambda^2 / (8 pi n0 n2) (Eq. 2); z_SF ~ L_R* / eta^k, eta = P0/P_c (Eq. 1); linear pressure scaling n2(mu) = mu n2^0, mu = p/p0 (Eq. 3); n2^0(t) = n_K^0 [1 + f_R h_R(t)] with a damped-oscillator Raman response (Eqs. 6-7; for air Omega_R = 16 THz, tau1 = 70 fs); n2^0(tau_p) = n2^sh [1 + Delta n_R(tau_p)] (Eq. 8), with Delta n_R from the ratio of z_SF of chirped (long) and short pulses at equal eta0 (Eq. 10), and the pressure dependence of n2^sh from n2^sh(p)/n2^sh(p0) = (1/mu) [z_SF^sh(p0)/z_SF^sh(p)]^(1/k) (Eq. 11), fitted with z_SF = L_R* [eta mu a (1 + b mu)]^-0.5 (Eq. 12, L_R* = 2.68 m).
Calibration: absolute values rest on Wahlstrand et al. (Phys. Rev. A 85, 043820 (2012), ref. 25): ‘The experimental data from Ref. [25] were used as a benchmark for the purely Kerr response of nitrogen and argon’ (p. 7), n2^sh = 7.4 (N2) and 9.7 x 10^-24 m^2/W (Ar) (p. 6). For CO2 at 1 bar: ‘in the case of the SP limit, the nonlinear response of CO2 is most similar in magnitude to that of argon. Consequently, we can estimate that the value of n2^sh(CO2) = 10^-23 m^2/W best suits the experimental data’ (p. 6); Table 1 prints 10.0 +- 1.1 (this work). So the CO2 value is in effect a ratio to Wahlstrand’s Ar, from z_SF comparisons. Check of the LP column: LP = SP x (1 + Delta n_R) with the paper’s Delta n_R(1 bar) at the longest pulse, 0.92 (N2) and 4.4 (CO2) (p. 7): 7.4 x 1.92 = 14.2 and 10.0 x 5.4 = 54.0, against 14.1 and 54.1 printed.
Table 1 (‘Optical Kerr nonlinearity (n2 x 10^24 m^2/W) of compressed gases at lambda = 800 nm’; SP tau_p = 50 fs, LP tau_p = 250...500 fs; tbl_2c05f4da79d1, JSON cells equal to the image): Ar SP 9.7 +- 1.5 (a, ref. 25), 18.9 +- 1.8, 26.2 +- 2.5; N2 SP 7.4 +- 0.9 (a), 14.4 +- 1.6, 20.1 +- 2.2 and LP 14.1 +- 1.5, 36.0 +- 3.9, 74.7 +- 8.5; CO2 SP 10.0 +- 1.1, 19.6 +- 2.0, 27.3 +- 2.6 and LP 54.1 +- 3.8, 121.5 +- 9.3, 333.1 +- 10.4 (1, 5, 11 bar). Geints quote Wahlstrand’s Ar value as 9.7 +- 1.5; Wahlstrand et al. 2012 (Table I, image) print 9.7 +- 1.2 (and N2 7.4 +- 0.9); Geints label them ‘1 bar’, Wahlstrand’s are at 1 atm.
The 5 and 11 bar values are excluded rows: they are not n2 at 5 or 11 bar (linear scaling would give 48.5 and 107 for Ar) but the pressure-normalised effective coefficient of Eq. (11) (the 1/mu factor), and its rise with pressure is attributed by the authors to beam aberration and modulation instability during self-focusing, not to the gas (p. 6, Conclusion). The interpretation of these columns as per-1-bar values is this record’s reading of Eq. (11); the paper does not state it.
Parts. Ar: electronic. N2 and CO2: the SP (50 fs) value still contains part of the rotational response (the paper’s Delta n_R is measured relative to it, p. 6-7) and the LP values contain much more: both part = instantaneous (pulse-dependent mixtures). Uncertainty: the +- of Table 1 (regression standard errors below 10 % for SP, p. 5; level not stated). State: ‘1 bar’ with no temperature: 100000 Pa and 293.15 K assumed. Wavelength 800 nm (central).
Recorded bibliographic identity status: VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
geints_2025/sp_CO2#
{
"id": "sp_CO2",
"material": "CO2",
"file": "CO2/geints_2025__sp_CO2.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "primary",
"excluded_rows": {
"sp_5bar": "Measured at 5 bar; the pressure-normalised effective value of Eq. (11), whose rise with pressure the authors attribute to beam aberration (p. 6).",
"sp_11bar": "Measured at 11 bar; pressure-normalised effective value, aberration-affected (p. 6)."
},
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "instantaneous",
"coefficient": "self",
"pulse_fs": 50
}
}
Table 1, SP (50 fs) column, 1 bar: 10.0 +- 1.1 x 10^-24 m^2/W, ‘for the first time’ for CO2 at 800 nm (abstract); in effect scaled to Wahlstrand’s Ar value (see the record’s notes). Contains part of the rotational response. 293.15 K assumed.
geints_2025/lp_CO2#
{
"id": "lp_CO2",
"material": "CO2",
"file": "CO2/geints_2025__lp_CO2.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "primary",
"excluded_rows": {
"lp_5bar": "Measured at 5 bar; pressure-normalised effective value (Eqs. 10-11), aberration-affected.",
"lp_11bar": "Measured at 11 bar; pressure-normalised effective value, aberration-affected."
},
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "instantaneous",
"coefficient": "self",
"pulse_fs": 500
}
}
Table 1, LP column, 1 bar: SP x (1 + Delta n_R) with Delta n_R = 4.4 for the longest (500 fs) chirped pulse (p. 7); the rotational response of CO2 was still growing at 500 fs (Fig. 6a). 293.15 K assumed.
geints_2025/lp_N2#
{
"id": "lp_N2",
"material": "N2",
"file": "N2/geints_2025__lp_N2.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "primary",
"excluded_rows": {
"lp_5bar": "Measured at 5 bar; pressure-normalised effective value (Eqs. 10-11), aberration-affected.",
"lp_11bar": "Measured at 11 bar; pressure-normalised effective value, aberration-affected."
},
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "instantaneous",
"coefficient": "self",
"pulse_fs": 300
}
}
Table 1, LP column, 1 bar: SP (Wahlstrand’s 7.4) x (1 + Delta n_R) with Delta n_R = 0.92 at the longest N2 pulse (data end at 300 fs, the response saturating at 250 fs, p. 7). The authors note their n2^sh/n2^lng = 0.52 against Wahlstrand’s 0.23 (p. 7). 293.15 K assumed.
geints_2025/sp_N2#
{
"id": "sp_N2",
"material": "N2",
"file": "N2/geints_2025__sp_N2.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "excluded",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "instantaneous",
"coefficient": "self",
"pulse_fs": 50
}
}
Table 1, SP column at 5 and 11 bar (the 1 bar value is Wahlstrand’s, dataset wahlstrand_2012_N2): pressure-normalised effective values (Eq. 11) relative to Wahlstrand’s 1 bar value; their rise with pressure is attributed by the authors to beam aberration (p. 6). Excluded; state is the 1 bar normalisation, not the measurement pressure.
geints_2025/sp_Ar#
{
"id": "sp_Ar",
"material": "Ar",
"file": "Ar/geints_2025__sp_Ar.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "excluded",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "electronic",
"coefficient": "self",
"pulse_fs": 50
}
}
Table 1, SP column at 5 and 11 bar (the 1 bar value is Wahlstrand’s, dataset wahlstrand_2012_Ar): pressure-normalised effective values (Eq. 11), aberration-affected (p. 6). Excluded; state is the 1 bar normalisation, not the measurement pressure.
geints_2025/wahlstrand_2012_Ar#
{
"id": "wahlstrand_2012_Ar",
"material": "Ar",
"file": "Ar/geints_2025__wahlstrand_2012_Ar.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "reproduced",
"reproduced_from": [
"wahlstrand_2012"
],
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "electronic",
"coefficient": "self"
}
}
Table 1, Ar SP 1 bar, footnote a (ref. 25): Wahlstrand et al. 2012’s 9.7, quoted with +- 1.5 (Wahlstrand print +- 1.2) and labelled 1 bar (Wahlstrand: 1 atm). Use the wahlstrand_2012 record.
geints_2025/wahlstrand_2012_N2#
{
"id": "wahlstrand_2012_N2",
"material": "N2",
"file": "N2/geints_2025__wahlstrand_2012_N2.csv",
"table": "tbl_2c05f4da79d1",
"quantity": "nonlinear_index",
"unit": "m2/W",
"scale": 1e-24,
"abscissa_unit": "nm",
"state": {
"pressure_pa": 100000.0,
"temperature_k": 293.15
},
"use": "reproduced",
"reproduced_from": [
"wahlstrand_2012"
],
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"part": "electronic",
"coefficient": "self"
}
}
Table 1, N2 SP 1 bar, footnote a (ref. 25): Wahlstrand et al. 2012’s electronic n2 7.4 +- 0.9, labelled 1 bar (Wahlstrand: 1 atm). Use the wahlstrand_2012 record.
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.