Optical constants

Refractive index of CaF₂ (Calcium fluoride)

Li 1980: n 0.15–12.0 µm; 20 °C

Data: formula 1
Range: 0.15–12 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.43388
Extinction coefficient k: 0

Permittivity ε₁: 2.05601
Permittivity ε₂: 0

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

Abbe number V_d: 95.313
Chromatic dispersion dn/dλ: -0.0235512 µm⁻¹

Group index n_g: 1.44772
Group velocity dispersion: 41.2611 fs²/mm

Dispersion parameter D: -225.101 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

# CaF2 (Calcium fluoride): Li 1980: n 0.15–12.0 µm; 20 °C
caf2 = ls.fetch_refractiveindex("main", "CaF2", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(caf2.range_nm)  # (150, 12000) nm
eps = caf2.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_30a50554ad0d/lightsmith"
caf2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(caf2.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (caf2/li-1980).

# ... load caf2 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=caf2)],
    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_30a50554ad0d/lightsmith?model=drude_lorentz"
caf2_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{0.69913 λ^{2}}{λ^{2} - {0.09374}^{2}} + \frac{0.11994 λ^{2}}{λ^{2} - {21.18}^{2}} + \frac{4.35181 λ^{2}}{λ^{2} - {38.46}^{2}}

Valid from 0.15 to 12.0 µm.

Coefficients as stored

C_i	Value
C1	0.33973
C2	0.69913
C3	0.09374
C4	0.11994
C5	21.18
C6	4.35181
C7	38.46

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.

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

CaF2 (Calcium fluoride), Li 1980: n 0.15–12.0 µm; 20 °C: n and k versus wavelength
λ (µm)	n
0.15	1.576956
0.151656	1.571954
0.153331	1.567176
0.155024	1.56261
0.156736	1.558242
0.158467	1.554061
0.160217	1.550055
0.161986	1.546216
0.163775	1.542533
0.165584	1.538998
0.167412	1.535603
0.169261	1.532341
0.17113	1.529205
0.17302	1.526187
0.174931	1.523284
0.176863	1.520487
0.178816	1.517793
0.18079	1.515197
0.182787	1.512694
0.184805	1.510279
0.186846	1.507948
0.18891	1.505698
0.190996	1.503525
0.193105	1.501426
0.195237	1.499397
0.197393	1.497436
0.199573	1.495539
0.201777	1.493704
0.204005	1.491928
0.206258	1.490209
0.208536	1.488544
0.210839	1.486932
0.213167	1.48537
0.215521	1.483856
0.217901	1.482389
0.220307	1.480967
0.22274	1.479587
0.2252	1.478249
0.227687	1.476951
0.230201	1.475691
0.232743	1.474468
0.235314	1.473281
0.237912	1.472128
0.240539	1.471008
0.243196	1.469921
0.245881	1.468864
0.248597	1.467837
0.251342	1.466839
0.254117	1.465869
0.256924	1.464926
0.259761	1.464009
0.262629	1.463117
0.26553	1.462249
0.268462	1.461405
0.271427	1.460584
0.274424	1.459784
0.277454	1.459007
0.280518	1.458249
0.283616	1.457512
0.286748	1.456795
0.289915	1.456096
0.293116	1.455415
0.296353	1.454753
0.299626	1.454107
0.302935	1.453478
0.30628	1.452865
0.309662	1.452268
0.313082	1.451686
0.316539	1.451119
0.320035	1.450566
0.323569	1.450027
0.327142	1.449501
0.330755	1.448989
0.334407	1.44849
0.3381	1.448002
0.341834	1.447527
0.345609	1.447064
0.349425	1.446612
0.353284	1.446171
0.357185	1.44574
0.36113	1.44532
0.365118	1.444911
0.36915	1.444511
0.373226	1.444121
0.377348	1.44374
0.381515	1.443368
0.385728	1.443005
0.389988	1.442651
0.394294	1.442305
0.398648	1.441967
0.403051	1.441637
0.407502	1.441315
0.412002	1.441001
0.416551	1.440693
0.421151	1.440393
0.425802	1.4401
0.430504	1.439813
0.435258	1.439533
0.440065	1.43926
0.444925	1.438993
0.449838	1.438731
0.454806	1.438476
0.459828	1.438227
0.464906	1.437983
0.47004	1.437744
0.475231	1.437511
0.480479	1.437283
0.485785	1.43706
0.491149	1.436842
0.496573	1.436629
0.502057	1.436421
0.507601	1.436217
0.513206	1.436017
0.518874	1.435822
0.524604	1.435631
0.530397	1.435444
0.536254	1.435261
0.542176	1.435082
0.548163	1.434906
0.554217	1.434735
0.560337	1.434567
0.566525	1.434402
0.572781	1.434241
0.579106	1.434083
0.585501	1.433929
0.591967	1.433777
0.598504	1.433629
0.605113	1.433483
0.611796	1.433341
0.618552	1.433201
0.625382	1.433064
0.632289	1.43293
0.639271	1.432798
0.64633	1.432669
0.653468	1.432542
0.660684	1.432418
0.66798	1.432296
0.675357	1.432176
0.682815	1.432059
0.690355	1.431944
0.697979	1.43183
0.705686	1.431719
0.713479	1.43161
0.721358	1.431502
0.729324	1.431396
0.737378	1.431293
0.745521	1.43119
0.753754	1.43109
0.762078	1.430991
0.770493	1.430894
0.779002	1.430798
0.787605	1.430704
0.796302	1.430611
0.805096	1.43052
0.813987	1.43043
0.822975	1.430341
0.832064	1.430253
0.841252	1.430167
0.850542	1.430082
0.859935	1.429997
0.869431	1.429914
0.879032	1.429832
0.888739	1.429751
0.898554	1.429671
0.908477	1.429592
0.918509	1.429514
0.928652	1.429436
0.938907	1.429359
0.949276	1.429283
0.959758	1.429208
0.970357	1.429133
0.981073	1.429059
0.991907	1.428986
1.00286	1.428913
1.01394	1.42884
1.02513	1.428769
1.03645	1.428697
1.0479	1.428626
1.05947	1.428555
1.07117	1.428485
1.083	1.428415
1.09496	1.428345
1.10705	1.428276
1.11928	1.428206
1.13164	1.428137
1.14413	1.428068
1.15677	1.427999
1.16954	1.427931
1.18246	1.427862
1.19551	1.427793
1.20872	1.427724
1.22206	1.427655
1.23556	1.427586
1.2492	1.427517
1.263	1.427448
1.27695	1.427378
1.29105	1.427308
1.30531	1.427238
1.31972	1.427168
1.33429	1.427097
1.34903	1.427026
1.36393	1.426954
1.37899	1.426882
1.39422	1.42681
1.40961	1.426737
1.42518	1.426663
1.44092	1.426589
1.45683	1.426514
1.47292	1.426439
1.48918	1.426363
1.50563	1.426286
1.52225	1.426208
1.53906	1.42613
1.55606	1.426051
1.57324	1.42597
1.59062	1.425889
1.60818	1.425807
1.62594	1.425724
1.6439	1.42564
1.66205	1.425554
1.68041	1.425468
1.69896	1.42538
1.71772	1.425292
1.73669	1.425201
1.75587	1.42511
1.77526	1.425017
1.79487	1.424923
1.81469	1.424828
1.83473	1.42473
1.85499	1.424632
1.87547	1.424532
1.89618	1.42443
1.91712	1.424326
1.93829	1.424221
1.9597	1.424114
1.98134	1.424005
2.00322	1.423894
2.02534	1.423781
2.04771	1.423666
2.07032	1.423549
2.09318	1.42343
2.1163	1.423309
2.13967	1.423185
2.1633	1.42306
2.18719	1.422931
2.21134	1.422801
2.23576	1.422668
2.26045	1.422532
2.28541	1.422394
2.31065	1.422253
2.33617	1.422109
2.36196	1.421962
2.38805	1.421813
2.41442	1.42166
2.44108	1.421505
2.46804	1.421346
2.49529	1.421184
2.52285	1.421019
2.55071	1.42085
2.57888	1.420678
2.60735	1.420502
2.63615	1.420323
2.66526	1.420139
2.69469	1.419952
2.72445	1.419762
2.75453	1.419567
2.78495	1.419367
2.81571	1.419164
2.8468	1.418956
2.87824	1.418744
2.91002	1.418528
2.94216	1.418306
2.97465	1.41808
3.0075	1.417849
3.04071	1.417613
3.07429	1.417372
3.10824	1.417126
3.14256	1.416874
3.17727	1.416617
3.21235	1.416354
3.24783	1.416085
3.28369	1.415811
3.31996	1.41553
3.35662	1.415243
3.39369	1.41495
3.43116	1.41465
3.46905	1.414344
3.50736	1.414031
3.54609	1.41371
3.58525	1.413383
3.62485	1.413048
3.66487	1.412706
3.70535	1.412356
3.74626	1.411998
3.78763	1.411632
3.82946	1.411258
3.87175	1.410875
3.91451	1.410484
3.95773	1.410084
4.00144	1.409674
4.04563	1.409256
4.0903	1.408828
4.13547	1.40839
4.18114	1.407942
4.22731	1.407483
4.274	1.407015
4.3212	1.406535
4.36891	1.406045
4.41716	1.405543
4.46594	1.405029
4.51526	1.404504
4.56512	1.403966
4.61553	1.403416
4.6665	1.402854
4.71803	1.402278
4.77014	1.401689
4.82281	1.401086
4.87607	1.400469
4.92992	1.399837
4.98436	1.399191
5.0394	1.398529
5.09505	1.397852
5.15132	1.397159
5.2082	1.39645
5.26572	1.395724
5.32387	1.39498
5.38266	1.394219
5.4421	1.39344
5.5022	1.392643
5.56296	1.391826
5.62439	1.39099
5.6865	1.390133
5.7493	1.389257
5.81279	1.388359
5.87698	1.387439
5.94188	1.386498
6.00749	1.385533
6.07384	1.384545
6.14091	1.383534
6.20872	1.382497
6.27729	1.381435
6.34661	1.380347
6.41669	1.379233
6.48755	1.378091
6.5592	1.376921
6.63163	1.375722
6.70486	1.374493
6.7789	1.373234
6.85376	1.371944
6.92945	1.370621
7.00597	1.369265
7.08334	1.367875
7.16156	1.36645
7.24065	1.364989
7.32061	1.36349
7.40145	1.361954
7.48318	1.360379
7.56582	1.358763
7.64937	1.357105
7.73384	1.355405
7.81925	1.353661
7.9056	1.351872
7.9929	1.350036
8.08116	1.348151
8.1704	1.346218
8.26063	1.344233
8.35185	1.342196
8.44408	1.340104
8.53733	1.337956
8.63161	1.335751
8.72693	1.333486
8.8233	1.33116
8.92074	1.328771
9.01925	1.326316
9.11885	1.323793
9.21955	1.321201
9.32136	1.318536
9.4243	1.315797
9.52837	1.31298
9.63359	1.310084
9.73998	1.307106
9.84754	1.304042
9.95628	1.300889
10.0662	1.297645
10.1774	1.294306
10.2898	1.290869
10.4034	1.287329
10.5183	1.283684
10.6345	1.279929
10.7519	1.27606
10.8706	1.272072
10.9907	1.267961
11.112	1.263721
11.2347	1.259349
11.3588	1.254837
11.4843	1.250181
11.6111	1.245374
11.7393	1.240409
11.8689	1.235281
12	1.22998

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: —

CaF₂ (Calcium fluoride): all datasets

About CaF2 (Calcium fluoride)

Calcium fluoride (CaF₂) is an inorganic compound with a cubic crystal structure, exhibiting excellent optical transparency over a wide range of wavelengths, from ultraviolet to infrared. It has a low refractive index (approximately 1.43 at 589 nm) and minimal chromatic dispersion, making it a preferred material for lenses, optical windows, and other components in spectroscopy and high-resolution imaging systems. Due to its low solubility and chemical stability, it is highly resistant to weathering and corrosion, making it suitable for harsh environments. In the realm of laser applications, CaF₂ is often used as an optical gain medium when doped with rare-earth ions such as ytterbium or erbium. The compound is synthesized through various methods, including precipitation from aqueous solutions and high-temperature reactions between calcium and fluorine gas. Its excellent optical, thermal, and chemical properties make calcium fluoride a material of considerable interest for a wide variety of optical and industrial applications. Mineral: Fluorite (fluorspar)

More about CaF2 (Calcium fluoride) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/CaF2/nk/Li.yml
ID: ds_30a50554ad0d
API: /v1/datasets/ds_30a50554ad0d

Plot