ermolov_2015
============

A\. Ermolov, K\. F\. Mak, M\. H\. Frosz, J\. C\. Travers and P\. St\.J\. Russell, Phys\. Rev\. A 92, 033821 \(2015\)

`Source record <https://github.com/LupoLab/optmat/blob/main/src/optmat/data/sources/ermolov_2015.toml>`__ · :doc:`Catalogue </the-data/sources>` · :doc:`Review register </register>`

DOI: `10\.1103/PhysRevA\.92\.033821 <https://doi.org/10.1103/PhysRevA.92.033821>`__

**Source kind:** fit

**Recorded technique:** A three\-term 'modified Sellmeier equation' for helium fitted to published refractive\-index data down to 90 nm \(Huber & Tondello 1974 is the one cited\)\.

**Materials in structured entries:** He

**Dataset quantities:** None recorded.

**Contents:** 0 datasets; 1 formula.

Curation notes
--------------

No datasets\: the paper's only refractive\-index content is its helium formula \(Eq\. \(3\) and Table I\)\. Table I \(tbl\_a8db8f8174bd\) lost its header row in extraction \(the first coefficient pair became the header\); the six coefficients are read from the table image\. Luna's \:He/\:HeJ \(PhysData\.jl\) uses the same coefficients with more digits \(2\.16463842e\-05, \-6\.80769781e\-04, \.\.\.\), recorded under source luna\_physdata\. The paper states the formula is 'for helium at 1 bar and 273 K' with rho 'the gas density relative to 1 bar at 273 K'; solprop instead references it to 1 atm because it then agrees with Mansfield & Peck \(1969\) to 0\.13 %\. The data comparison here will say which state the fit really corresponds to\.

Third\-order values\: none printed\. The simulations \(a multimode, carrier\-resolved unidirectional propagation equation with the Kerr effect, self\-focusing, ionisation and plasma, ref\. 50\) state only 'The nonlinear refractive index data was taken from \[51\]' \(pdf p\. 4\), ref\. 51 being Lehmeier, Leupacher & Penzkofer, Opt\. Commun\. 56, 67 \(1985\) \(record lehmeier\_1985\: THG hyperpolarizabilities at 1055 nm, P = 4 eps0 chi E E E\), for the He and Ne fillings; no value, convention or conversion is given\. The other nonlinear citation, ref\. 25 \(Boling, Glass & Owyoung, IEEE J\. Quantum Electron\. 14, 601 \(1978\)\), concerns optical solids and is cited only for the trend of lower nonlinearity with higher ionisation potential\. No third\-order dataset is added\.

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

Datasets
--------

No datasets are recorded.

Formulas
--------

ermolov\_2015/sellmeier\_He
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "sellmeier_He",
     "material": "He",
     "equation": "Eq. (3) and Table I, p. 5",
     "printed": "n0^2(lambda) - 1 = rho sum_{i=1}^3 B_i lambda^2 / (lambda^2 - C_i); B1 = 2.16463e-5, C1 = -6.8077e-4, B2 = 2.10561e-7, C2 = 5.13251e-3, B3 = 4.75093e-5, C3 = 3.18621e-3",
     "variable": "lambda: wavelength in um; rho: density relative to 1 bar at 273 K",
     "form": "n2_sellmeier",
     "terms": {
       "B": [
         "2.16463e-5",
         "2.10561e-7",
         "4.75093e-5"
       ],
       "C": [
         "-6.8077e-4",
         "5.13251e-3",
         "3.18621e-3"
       ]
     },
     "state": "1bar_0C",
     "density": "real",
     "range_nm": [
       90.0,
       1000.0
     ],
     "check": "Not checkable against the paper, which prints no values of n."
   }

C1 \< 0 puts the first 'pole' at an imaginary wavelength\: the term is a smooth background, not a resonance\. The paper states no range; 90 nm is the short end of the data it cites, 1000 nm the long end of what Luna PR \#425 and solprop assume\. 273 K is read as 273\.15 K\.

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 :doc:`review register </register>` for the checks and decisions.