Optical constants

Refractive index of SrF₂ (Strontium fluoride)

Li 1980: n 0.15–12.0 µm

Data: formula 1
Range: 0.15–14 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.4381
Extinction coefficient k: 0

Permittivity ε₁: 2.06814
Permittivity ε₂: 0

Absorption coefficient α: 0 cm⁻¹
Penetration depth δ = λ/(2πk): — nm

Abbe number V_d: 92.129
Chromatic dispersion dn/dλ: -0.0245185 µm⁻¹

Group index n_g: 1.45251
Group velocity dispersion: 44.279 fs²/mm

Dispersion parameter D: -241.566 ps/(nm·km)
Photon energy: 2.11001 eV

ε = (n + ik)², α = 4πk/λ, n_g = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith

import lightsmith as ls

# SrF2 (Strontium fluoride): Li 1980: n 0.15–12.0 µm
srf2 = ls.fetch_refractiveindex("main", "SrF2", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(srf2.range_nm)  # (150, 14000) nm
eps = srf2.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_e9f4973e764e/lightsmith"
srf2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(srf2.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (srf2/li-1980).

# ... load srf2 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=srf2)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength

Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_e9f4973e764e/lightsmith?model=drude_lorentz"
srf2_dl = ls.DrudeLorentz.model_validate(json.load(urllib.request.urlopen(url)))

A dispersive Drude–Lorentz model for time-domain solvers.

Materials guide Open a sphere of it in Studio Quick start Ask the community

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Dispersion formula

Sellmeier (formula 1), λ in µm

n^{2} - 1 = 0.33973 + \frac{0.7097 λ^{2}}{λ^{2} - {0.09597}^{2}} + \frac{0.1788 λ^{2}}{λ^{2} - {26.03}^{2}} + \frac{3.8796 λ^{2}}{λ^{2} - {45.6}^{2}}

Valid from 0.15 to 14.0 µm.

Coefficients as stored

C_i	Value
C1	0.33973
C2	0.7097
C3	0.09597
C4	0.1788
C5	26.03
C6	3.8796
C7	45.6

Comments and conditions

293 K (20 °C).

References

H. H. Li. Refractive index of alkaline earth halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 9, 161-289 (1980) and references therein.
* Sellmeier formula is derived by critical analysis of experimental data from several sources.
** There is a misprint in the dispersion formula in the paper: "-" instead of "+" before the last term of the equation.

doi:10.1063/1.555616 Refractive index of alkaline earth halides and its wavelength and temperature derivatives, Journal of Physical and Chemical Reference Data (1980)

Cite

H. H. Li. Refractive index of alkaline earth halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data, 9, 161-290 (1980), doi:10.1063/1.555616; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

Computed on 400 wavelengths, the same grid as the API and the library

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

SrF2 (Strontium fluoride), Li 1980: n 0.15–12.0 µm: n and k versus wavelength
λ (µm)	n
0.15	1.594123
0.151715	1.58833
0.15345	1.582818
0.155204	1.577566
0.156979	1.572559
0.158774	1.567781
0.160589	1.563218
0.162425	1.558855
0.164282	1.554682
0.166161	1.550688
0.16806	1.546862
0.169982	1.543194
0.171926	1.539675
0.173891	1.536299
0.17588	1.533056
0.177891	1.529941
0.179924	1.526945
0.181982	1.524064
0.184062	1.521292
0.186167	1.518623
0.188296	1.516051
0.190448	1.513574
0.192626	1.511185
0.194828	1.508881
0.197056	1.506659
0.199309	1.504513
0.201588	1.502442
0.203893	1.500441
0.206224	1.498507
0.208582	1.496639
0.210967	1.494832
0.213379	1.493084
0.215819	1.491394
0.218286	1.489758
0.220782	1.488174
0.223307	1.486641
0.22586	1.485156
0.228442	1.483717
0.231054	1.482323
0.233696	1.480972
0.236368	1.479662
0.239071	1.478392
0.241804	1.47716
0.244569	1.475965
0.247365	1.474806
0.250193	1.47368
0.253054	1.472588
0.255947	1.471528
0.258874	1.470498
0.261834	1.469498
0.264827	1.468527
0.267855	1.467583
0.270918	1.466666
0.274016	1.465775
0.277149	1.464909
0.280318	1.464067
0.283523	1.463249
0.286764	1.462452
0.290043	1.461678
0.293359	1.460925
0.296714	1.460193
0.300106	1.45948
0.303537	1.458787
0.307008	1.458112
0.310518	1.457455
0.314069	1.456816
0.31766	1.456193
0.321292	1.455587
0.324965	1.454997
0.328681	1.454423
0.332439	1.453863
0.33624	1.453318
0.340084	1.452787
0.343973	1.45227
0.347906	1.451766
0.351884	1.451275
0.355907	1.450796
0.359976	1.45033
0.364092	1.449875
0.368255	1.449432
0.372466	1.449
0.376724	1.448579
0.381032	1.448169
0.385388	1.447768
0.389795	1.447378
0.394251	1.446997
0.398759	1.446626
0.403319	1.446264
0.40793	1.445911
0.412594	1.445566
0.417312	1.44523
0.422083	1.444902
0.426909	1.444582
0.43179	1.444269
0.436727	1.443965
0.441721	1.443667
0.446771	1.443377
0.451879	1.443093
0.457046	1.442817
0.462272	1.442547
0.467557	1.442283
0.472903	1.442025
0.47831	1.441774
0.483779	1.441528
0.489311	1.441289
0.494905	1.441055
0.500564	1.440826
0.506287	1.440602
0.512076	1.440384
0.517931	1.440171
0.523853	1.439962
0.529842	1.439759
0.5359	1.43956
0.542028	1.439365
0.548225	1.439175
0.554493	1.43899
0.560833	1.438808
0.567246	1.43863
0.573731	1.438457
0.580291	1.438287
0.586926	1.438121
0.593637	1.437959
0.600424	1.4378
0.60729	1.437645
0.614233	1.437493
0.621256	1.437344
0.628359	1.437198
0.635544	1.437056
0.642811	1.436917
0.65016	1.43678
0.657594	1.436647
0.665113	1.436516
0.672718	1.436388
0.680409	1.436262
0.688189	1.436139
0.696057	1.436019
0.704016	1.435901
0.712065	1.435785
0.720207	1.435672
0.728442	1.435561
0.736771	1.435452
0.745195	1.435345
0.753715	1.435241
0.762333	1.435138
0.771049	1.435037
0.779865	1.434938
0.788782	1.434841
0.7978	1.434745
0.806922	1.434652
0.816148	1.43456
0.82548	1.434469
0.834918	1.43438
0.844465	1.434293
0.85412	1.434207
0.863886	1.434123
0.873763	1.43404
0.883754	1.433958
0.893858	1.433877
0.904078	1.433798
0.914415	1.43372
0.924871	1.433643
0.935445	1.433567
0.946141	1.433492
0.956959	1.433419
0.9679	1.433346
0.978967	1.433274
0.99016	1.433203
1.00148	1.433133
1.01293	1.433064
1.02451	1.432995
1.03623	1.432928
1.04808	1.432861
1.06006	1.432795
1.07218	1.432729
1.08444	1.432664
1.09684	1.432599
1.10938	1.432536
1.12206	1.432472
1.13489	1.432409
1.14787	1.432347
1.16099	1.432285
1.17427	1.432223
1.18769	1.432162
1.20127	1.432101
1.21501	1.43204
1.2289	1.43198
1.24295	1.431919
1.25716	1.431859
1.27154	1.431799
1.28608	1.43174
1.30078	1.43168
1.31565	1.43162
1.3307	1.431561
1.34591	1.431501
1.3613	1.431441
1.37686	1.431381
1.39261	1.431322
1.40853	1.431262
1.42463	1.431201
1.44092	1.431141
1.4574	1.431081
1.47406	1.43102
1.49092	1.430959
1.50796	1.430897
1.5252	1.430835
1.54264	1.430773
1.56028	1.430711
1.57812	1.430648
1.59617	1.430584
1.61442	1.43052
1.63287	1.430455
1.65154	1.43039
1.67043	1.430324
1.68953	1.430258
1.70884	1.430191
1.72838	1.430123
1.74814	1.430054
1.76813	1.429985
1.78835	1.429915
1.8088	1.429843
1.82948	1.429771
1.8504	1.429698
1.87155	1.429624
1.89295	1.429549
1.91459	1.429473
1.93649	1.429396
1.95863	1.429318
1.98102	1.429238
2.00367	1.429157
2.02658	1.429076
2.04975	1.428992
2.07319	1.428908
2.09689	1.428821
2.12087	1.428734
2.14512	1.428645
2.16964	1.428554
2.19445	1.428462
2.21954	1.428368
2.24492	1.428273
2.27059	1.428176
2.29655	1.428077
2.32281	1.427976
2.34937	1.427873
2.37623	1.427769
2.4034	1.427662
2.43088	1.427553
2.45867	1.427442
2.48678	1.427329
2.51522	1.427214
2.54397	1.427097
2.57306	1.426977
2.60248	1.426854
2.63224	1.426729
2.66233	1.426602
2.69277	1.426472
2.72356	1.426339
2.7547	1.426204
2.7862	1.426065
2.81806	1.425924
2.85028	1.42578
2.88287	1.425633
2.91583	1.425482
2.94917	1.425329
2.98289	1.425172
3.01699	1.425011
3.05149	1.424847
3.08638	1.42468
3.12167	1.424509
3.15736	1.424334
3.19346	1.424155
3.22997	1.423973
3.2669	1.423786
3.30426	1.423595
3.34204	1.4234
3.38025	1.4232
3.4189	1.422996
3.45799	1.422788
3.49753	1.422575
3.53752	1.422357
3.57796	1.422134
3.61887	1.421906
3.66025	1.421673
3.7021	1.421434
3.74443	1.42119
3.78724	1.420941
3.83054	1.420685
3.87434	1.420424
3.91864	1.420157
3.96344	1.419884
4.00876	1.419604
4.0546	1.419318
4.10095	1.419026
4.14784	1.418726
4.19527	1.41842
4.24324	1.418106
4.29175	1.417785
4.34082	1.417457
4.39046	1.417121
4.44066	1.416777
4.49143	1.416425
4.54278	1.416065
4.59472	1.415696
4.64726	1.415319
4.70039	1.414933
4.75414	1.414537
4.80849	1.414133
4.86347	1.413718
4.91908	1.413294
4.97532	1.41286
5.03221	1.412415
5.08975	1.41196
5.14794	1.411494
5.2068	1.411017
5.26634	1.410528
5.32655	1.410028
5.38745	1.409515
5.44905	1.408991
5.51135	1.408453
5.57437	1.407903
5.63811	1.407339
5.70257	1.406762
5.76777	1.406171
5.83372	1.405565
5.90042	1.404945
5.96788	1.404309
6.03612	1.403659
6.10513	1.402992
6.17494	1.402308
6.24554	1.401609
6.31695	1.400891
6.38918	1.400157
6.46223	1.399404
6.53612	1.398632
6.61085	1.397842
6.68644	1.397031
6.76289	1.396201
6.84021	1.39535
6.91842	1.394477
6.99753	1.393583
7.07753	1.392667
7.15846	1.391727
7.2403	1.390764
7.32309	1.389776
7.40682	1.388764
7.49151	1.387726
7.57716	1.386661
7.6638	1.385569
7.75142	1.38445
7.84005	1.383301
7.92969	1.382124
8.02036	1.380915
8.11206	1.379676
8.20481	1.378405
8.29862	1.3771
8.39351	1.375761
8.48948	1.374388
8.58654	1.372978
8.68472	1.371532
8.78402	1.370047
8.88445	1.368523
8.98603	1.366958
9.08878	1.365351
9.1927	1.363702
9.2978	1.362008
9.40411	1.360268
9.51164	1.358482
9.62039	1.356646
9.73039	1.354761
9.84164	1.352823
9.95417	1.350833
10.068	1.348787
10.1831	1.346684
10.2995	1.344523
10.4173	1.3423
10.5364	1.340015
10.6569	1.337665
10.7787	1.335248
10.902	1.332762
11.0266	1.330204
11.1527	1.327571
11.2802	1.324862
11.4092	1.322073
11.5396	1.319202
11.6716	1.316245
11.805	1.313199
11.94	1.310062
12.0765	1.306829
12.2146	1.303497
12.3542	1.300062
12.4955	1.29652
12.6384	1.292867
12.7829	1.289099
12.929	1.28521
13.0769	1.281197
13.2264	1.277052
13.3776	1.272772
13.5306	1.268351
13.6853	1.263781
13.8417	1.259056
14	1.25417

Optical transmission calculator

Free-standing sample in vacuum, normal incidence

Transmittance T: —
Reflectance R: —

Fresnel reflection calculator

R_p: —
R_s: —
R = (R_p+R_s)/2: —
Phase φ_p: —
Phase φ_s: —
Brewster angle θ_B: —
Critical angle θ_C: —

SrF₂ (Strontium fluoride): all datasets

About SrF2 (Strontium fluoride)

Strontium fluoride (SrF₂) is an inorganic compound that appears as a white crystalline solid at room temperature. With a high melting point and good thermal stability, it is often used in optical applications due to its notable transparency to ultraviolet and visible wavelengths. Its optical clarity has led to its use in the manufacture of windows and lenses, especially in specialized optical systems. Additionally, SrF₂ is employed as a thin film in the production of optical coatings, thanks to its low refractive index. Moreover, the compound is explored for potential use in fluoride ion batteries due to its high ionic conductivity. In nature, strontium fluoride occurs as the mineral strontianite, though most commercial preparations are synthesized through chemical reactions.

More about SrF2 (Strontium fluoride) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/SrF2/nk/Li.yml
ID: ds_e9f4973e764e
API: /v1/datasets/ds_e9f4973e764e

Plot