cheng_2018

S. Cheng, G. Chatterjee, F. Tellkamp, A. Ruehl and R. J. D. Miller, “Multi-octave supercontinuum generation in YAG pumped by mid-infrared, multi-picosecond pulses”, Opt. Lett. 43, 4329 (2018)

Source record · Catalogue · Review register

DOI: 10.1364/ol.43.004329

Source kind: measurement

Recorded technique: Supercontinuum generation in 5-15-cm YAG crystals by near-transform-limited 3.0-ps pulses at 2.05 um (Ho:YLF regenerative amplifier, 1 kHz) focused with NA 0.001-0.005 (50-100 cm lenses and an iris); spectra 200 nm - 4.3 um, SHG-FROG of the output. A simple rate-equation estimate (Keldysh ionization seeding a Drude avalanche) sets the breakdown intensity and so the NA.

Materials in structured entries: YAG

Dataset quantities: avalanche_coefficient, band_gap, damage_threshold_energy, damage_threshold_intensity, electron_collision_time, multiphoton_ionization_cross_section

Contents: 6 datasets; 1 formula.

Curation notes

Journal pages 4329-4332 = PDF pages 1-4. Identity validated.

MEASURED: ‘The filament formation was initiated at the rear end of the 15 cm YAG crystal for a pump energy of ~17 uJ and was found to shift towards the front end of the crystal upon increasing the pump energy until ~175 uJ, which was determined as the threshold for irreversible crystal damage. At this energy, the filament started ~5 cm from the front end of the crystal’ (p. 4330): recorded as a bulk damage-threshold energy (15-cm crystal, NA ~0.005, 3.0 ps, 2.05 um, 1 kHz; the damage criterion and the number of shots are not stated). The continuum at 150 uJ spans 500 nm - 3.5 um at -30 dB (to 4.5 um), 1.9 % rms over 20 min, >60 % efficiency with ~1 uJ above 2.4 um at 120 uJ (no curated quantity). Crystal orientation and polarization not stated.

RATE-EQUATION ESTIMATE (p. 4330, inputs assumed): ‘YAG with a bandgap energy of U_i = 6.5 eV [4,18]’ (silva_2012; Xu and Ching, Phys. Rev. B 59, 10530 (1999)); the multiphoton asymptote ‘W_MPI = sigma_11 I^11, where sigma_11 = 1.3 x 10^-126 s^-1 (W/cm2)^-11 for rho_0 = 7 x 10^22 cm^-3 [4]’: silva_2012 prints neither (its rates are in the supplementary information, not in the library); ‘an estimated collision time tau_c = 3 fs [4] yields an inverse Bremsstrahlung coefficient of sigma_IB = 2.06 x 10^-17 cm2’; the result, a threshold I_th ~ 3 x 10^11 W/cm2 for the 3-ps pulse, where the density reaches ‘the plasma critical density rho_c = 2.6 x 10^20 cm^-3’, so the NA must be <~ 0.005 for ~10 P_cr at <~ 1e11 W/cm2. The background neutral density rho_0 = 7e22 cm^-3 is not recorded as an atom_density dataset: ‘neutral density’ does not say whether atoms or formula units are counted (a vocabulary gap, reported).

CHECKS (2026-09-26): sigma_IB = e^2 tau_c/(m_e n0 eps0 c (1 + omega0^2 tau_c^2)) = 3.70e-17/n0 cm2 at 2.05 um, 2.06e-17 for n0 = 1.80 (n0 not stated); rho_c = omega0^2 eps0 m_e/e^2 = 2.65e20 cm^-3 (printed 2.6e20); 6.5 eV/0.605 eV = 10.7, so 11 photons. silva_2012 gives sigma = 2.6e-20 cm2 at 3.1 um for the same tau_c, which is not the Drude value (see silva_2012).

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

Datasets

cheng_2018/damage_energy

{
  "id": "damage_energy",
  "material": "YAG",
  "table": "text",
  "quantity": "damage_threshold_energy",
  "unit": "uJ",
  "abscissa": "duration",
  "abscissa_unit": "ps",
  "use": "primary",
  "parameters": {
    "site": "bulk",
    "criterion": "irreversible crystal damage (not further specified)",
    "wavelength_nm": 2050,
    "numerical_aperture": 0.005,
    "shots": "not stated (1 kHz)"
  }
}

1 inline points in the source record.

p. 4330: ‘~175 uJ, which was determined as the threshold for irreversible crystal damage’ in the 15-cm crystal with NA ~0.005 (Rayleigh length ~12 cm); pulse 3.0 ps FWHM (FROG, Fig. 5). Approximate (‘~’); uncertainty not stated.

cheng_2018/model_band_gap

{
  "id": "model_band_gap",
  "material": "YAG",
  "table": "text",
  "quantity": "band_gap",
  "unit": "eV",
  "abscissa": "none",
  "use": "check",
  "reproduced_from": [
    "silva_2012",
    "Y.-N. Xu and W. Y. Ching, Phys. Rev. B 59, 10530 (1999)"
  ],
  "parameters": {
    "kind": "assumed",
    "assumed": true
  }
}

1 inline points in the source record.

p. 4330: ‘for YAG with a bandgap energy of U_i = 6.5 eV [4,18]’.

cheng_2018/model_sigma11

{
  "id": "model_sigma11",
  "material": "YAG",
  "table": "text",
  "quantity": "multiphoton_ionization_cross_section",
  "unit": "s-1 (W/cm2)-11",
  "abscissa_unit": "nm",
  "use": "check",
  "reproduced_from": [
    "silva_2012"
  ],
  "parameters": {
    "photons": 11,
    "assumed": true
  }
}

1 inline points in the source record.

p. 4330: ‘W_MPI = sigma_11 I^11, where sigma_11 = 1.3 x 10^-126 s^-1 (W/cm2)^-11 for rho_0 = 7 x 10^22 cm^-3 [4]’, the low-intensity asymptote of their Keldysh rate at 2.05 um (Fig. 1a). The printed unit makes it a rate per atom; ‘for rho_0’ says the per-volume rate uses rho_0 = 7e22 cm^-3. silva_2012’s main text does not print it (its Supplementary Fig. S2 may).

cheng_2018/model_collision_time

{
  "id": "model_collision_time",
  "material": "YAG",
  "table": "text",
  "quantity": "electron_collision_time",
  "unit": "fs",
  "abscissa": "none",
  "use": "check",
  "reproduced_from": [
    "silva_2012"
  ],
  "parameters": {
    "assumed": true
  }
}

1 inline points in the source record.

p. 4330: ‘an estimated collision time tau_c = 3 fs [4]’.

cheng_2018/model_avalanche_cross_section

{
  "id": "model_avalanche_cross_section",
  "material": "YAG",
  "table": "text",
  "quantity": "avalanche_coefficient",
  "unit": "cm2",
  "abscissa_unit": "nm",
  "use": "check",
  "parameters": {
    "definition": "sigma_IB in W_AI = sigma_IB I/U_i, d rho/dt = W_OFI(I)(rho_0 - rho) + W_AI(I) rho",
    "assumed": true
  }
}

1 inline points in the source record.

p. 4330: ‘W_AI = sigma_IB I/U_i ... according to the Drude model, where an estimated collision time tau_c = 3 fs [4] yields an inverse Bremsstrahlung coefficient of sigma_IB = 2.06 x 10^-17 cm2’; the Drude value for n0 = 1.80 (source notes).

cheng_2018/model_breakdown_intensity

{
  "id": "model_breakdown_intensity",
  "material": "YAG",
  "table": "text",
  "quantity": "damage_threshold_intensity",
  "unit": "W/cm2",
  "abscissa": "duration",
  "abscissa_unit": "ps",
  "use": "check",
  "parameters": {
    "site": "bulk",
    "criterion": "calculated: electron density reaching rho_c = 2.6e20 cm^-3",
    "wavelength_nm": 2050
  }
}

1 inline points in the source record.

p. 4330 (Fig. 1b): calculated, ‘beyond a threshold intensity of I_th ~ 3 x 10^11 W/cm2 the electron density rho(t) rapidly reaches the plasma critical density rho_c = 2.6 x 10^20 cm^-3 for the duration of our pump pulse’. A model estimate.

Formulas

cheng_2018/rate_equation

{
  "id": "rate_equation",
  "material": "YAG",
  "equation": "p. 4330 (text)",
  "printed": "d rho/dt = W_OFI(I)(rho_0 - rho) + W_AI(I) rho; W_MPI = sigma_11 I^11; W_AI = sigma_IB I/U_i",
  "variable": "rho: electron density; rho_0 the background neutral density; W_OFI the Keldysh optical-field-ionization rate (refs. 1, 17)",
  "coefficients": {
    "U_i": "6.5 eV",
    "sigma_11": "1.3e-126 s^-1 (W/cm^2)^-11",
    "rho_0": "7e22 cm^-3",
    "tau_c": "3 fs",
    "sigma_IB": "2.06e-17 cm^2",
    "rho_c": "2.6e20 cm^-3"
  },
  "reproduced_from": [
    "silva_2012",
    "couairon_2005"
  ],
  "check": "sigma_IB and rho_c checked (source notes); I_th ~ 3e11 W/cm2 not recomputed (the Keldysh rate is a figure)."
}

The library text renders the avalanche term as W_AI(I) rho~ (a lost glyph).

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.