Optical constants

Refractive index of LiBr (Lithium bromide)

Li 1976: n 0.21–20 µm

Data: formula 1
Range: 0.21–20 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.78399
Extinction coefficient k: 0

Permittivity ε₁: 3.18261
Permittivity ε₂: 0

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

Abbe number V_d: 156.41
Chromatic dispersion dn/dλ: -0.0254639 µm⁻¹

Group index n_g: 1.79895
Group velocity dispersion: 49.2042 fs²/mm

Dispersion parameter D: -268.435 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

# LiBr (Lithium bromide): Li 1976: n 0.21–20 µm
libr = ls.fetch_refractiveindex("main", "LiBr", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(libr.range_nm)  # (210, 20000) nm
eps = libr.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_d564678c98e1/lightsmith"
libr = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(libr.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (libr/li-1976).

# ... load libr as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=libr)],
    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_d564678c98e1/lightsmith?model=drude_lorentz"
libr_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 = 1.88 + \frac{0.28 λ^{2}}{λ^{2} - {0.164}^{2}} + \frac{10.07 λ^{2}}{λ^{2} - {57.8}^{2}}

Valid from 0.21 to 20.0 µm.

Coefficients as stored

C_i	Value
C1	1.88
C2	0.28
C3	0.164
C4	10.07
C5	57.8

Comments and conditions

297 K (24 °C).

References

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 5, 329-528 (1976) and references therein.
* Sellmeier formula derivation is based on a single data point and knowledge of the dielectric constants and the characteristic absorption peaks.

doi:10.1063/1.555536 Refractive index of alkali halides and its wavelength and temperature derivatives, Journal of Physical and Chemical Reference Data (1976)

Cite

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data, 5, 329-528 (1976), doi:10.1063/1.555536; 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

LiBr (Lithium bromide), Li 1976: n 0.21–20 µm: n and k versus wavelength
λ (µm)	n
0.21	1.896736
0.212412	1.890273
0.214851	1.884348
0.217319	1.878899
0.219815	1.873871
0.222339	1.869219
0.224893	1.864903
0.227476	1.860889
0.230088	1.857146
0.232731	1.85365
0.235404	1.850378
0.238107	1.847309
0.240842	1.844426
0.243608	1.841713
0.246406	1.839155
0.249236	1.836742
0.252098	1.834461
0.254994	1.832302
0.257922	1.830257
0.260885	1.828316
0.263881	1.826473
0.266911	1.824721
0.269977	1.823054
0.273078	1.821466
0.276214	1.819951
0.279386	1.818506
0.282595	1.817126
0.285841	1.815807
0.289123	1.814546
0.292444	1.813338
0.295803	1.812181
0.2992	1.811073
0.302636	1.810009
0.306112	1.808989
0.309628	1.808009
0.313184	1.807067
0.316781	1.806162
0.320419	1.805292
0.324099	1.804454
0.327821	1.803648
0.331586	1.802871
0.335394	1.802122
0.339246	1.801401
0.343143	1.800705
0.347084	1.800033
0.35107	1.799385
0.355102	1.798759
0.35918	1.798155
0.363305	1.797571
0.367478	1.797006
0.371698	1.79646
0.375967	1.795932
0.380285	1.795421
0.384653	1.794926
0.38907	1.794448
0.393539	1.793984
0.398059	1.793535
0.40263	1.7931
0.407255	1.792678
0.411932	1.792269
0.416663	1.791873
0.421448	1.791488
0.426289	1.791115
0.431184	1.790753
0.436137	1.790402
0.441146	1.790061
0.446212	1.789729
0.451337	1.789408
0.45652	1.789095
0.461764	1.788791
0.467067	1.788496
0.472431	1.788209
0.477857	1.78793
0.483345	1.787659
0.488896	1.787395
0.494511	1.787139
0.500191	1.786889
0.505935	1.786646
0.511746	1.786409
0.517623	1.786179
0.523568	1.785955
0.529581	1.785737
0.535664	1.785524
0.541816	1.785317
0.548038	1.785115
0.554333	1.784918
0.560699	1.784726
0.567139	1.784539
0.573652	1.784357
0.580241	1.784179
0.586905	1.784006
0.593645	1.783836
0.600463	1.783671
0.60736	1.78351
0.614335	1.783353
0.621391	1.783199
0.628527	1.783049
0.635746	1.782903
0.643047	1.78276
0.650433	1.78262
0.657903	1.782483
0.665459	1.78235
0.673102	1.782219
0.680832	1.782091
0.688652	1.781967
0.696561	1.781844
0.704561	1.781725
0.712652	1.781608
0.720837	1.781493
0.729116	1.781381
0.73749	1.781271
0.74596	1.781164
0.754527	1.781058
0.763193	1.780955
0.771958	1.780853
0.780824	1.780754
0.789792	1.780656
0.798863	1.780561
0.808037	1.780467
0.817318	1.780374
0.826705	1.780284
0.836199	1.780195
0.845803	1.780107
0.855517	1.780021
0.865342	1.779937
0.875281	1.779853
0.885333	1.779771
0.895501	1.779691
0.905786	1.779611
0.916189	1.779533
0.926712	1.779456
0.937355	1.77938
0.94812	1.779305
0.959009	1.779231
0.970024	1.779158
0.981164	1.779085
0.992433	1.779014
1.00383	1.778944
1.01536	1.778874
1.02702	1.778805
1.03882	1.778736
1.05075	1.778669
1.06282	1.778602
1.07502	1.778535
1.08737	1.778469
1.09986	1.778404
1.11249	1.778339
1.12527	1.778274
1.13819	1.77821
1.15126	1.778146
1.16448	1.778082
1.17786	1.778019
1.19138	1.777956
1.20507	1.777893
1.21891	1.777831
1.23291	1.777768
1.24707	1.777706
1.26139	1.777643
1.27588	1.777581
1.29053	1.777519
1.30535	1.777457
1.32034	1.777394
1.33551	1.777332
1.35085	1.777269
1.36636	1.777206
1.38205	1.777143
1.39793	1.77708
1.41398	1.777017
1.43022	1.776953
1.44665	1.776889
1.46326	1.776824
1.48007	1.776759
1.49706	1.776694
1.51426	1.776628
1.53165	1.776562
1.54924	1.776495
1.56703	1.776427
1.58503	1.776359
1.60323	1.77629
1.62165	1.776221
1.64027	1.776151
1.65911	1.77608
1.67817	1.776008
1.69744	1.775935
1.71693	1.775862
1.73665	1.775787
1.7566	1.775712
1.77677	1.775635
1.79718	1.775558
1.81782	1.77548
1.8387	1.7754
1.85981	1.775319
1.88117	1.775237
1.90278	1.775154
1.92463	1.775069
1.94674	1.774983
1.96909	1.774896
1.99171	1.774807
2.01458	1.774717
2.03772	1.774625
2.06113	1.774532
2.0848	1.774437
2.10874	1.77434
2.13296	1.774242
2.15746	1.774141
2.18223	1.774039
2.2073	1.773935
2.23265	1.77383
2.25829	1.773722
2.28423	1.773612
2.31046	1.7735
2.337	1.773386
2.36384	1.773269
2.39099	1.77315
2.41845	1.773029
2.44622	1.772906
2.47432	1.77278
2.50273	1.772651
2.53148	1.77252
2.56055	1.772386
2.58996	1.772249
2.6197	1.77211
2.64979	1.771967
2.68022	1.771822
2.71101	1.771673
2.74214	1.771522
2.77364	1.771367
2.80549	1.771209
2.83771	1.771047
2.8703	1.770882
2.90327	1.770713
2.93661	1.770541
2.97034	1.770365
3.00445	1.770185
3.03896	1.770001
3.07386	1.769813
3.10916	1.769621
3.14487	1.769425
3.18099	1.769224
3.21753	1.769019
3.25448	1.768809
3.29186	1.768595
3.32966	1.768376
3.3679	1.768151
3.40658	1.767922
3.44571	1.767688
3.48528	1.767448
3.52531	1.767203
3.5658	1.766953
3.60675	1.766696
3.64817	1.766434
3.69007	1.766166
3.73245	1.765892
3.77532	1.765611
3.81868	1.765324
3.86254	1.765031
3.9069	1.764731
3.95177	1.764424
3.99716	1.764109
4.04306	1.763788
4.0895	1.763459
4.13646	1.763123
4.18397	1.762778
4.23202	1.762426
4.28063	1.762066
4.32979	1.761697
4.37952	1.761319
4.42982	1.760933
4.48069	1.760538
4.53215	1.760134
4.58421	1.75972
4.63686	1.759296
4.69011	1.758863
4.74398	1.75842
4.79846	1.757966
4.85357	1.757501
4.90931	1.757025
4.9657	1.756539
5.02273	1.756041
5.08041	1.755531
5.13876	1.755009
5.19778	1.754474
5.25748	1.753927
5.31786	1.753368
5.37893	1.752795
5.44071	1.752208
5.5032	1.751607
5.5664	1.750992
5.63033	1.750363
5.69499	1.749718
5.7604	1.749058
5.82656	1.748383
5.89348	1.747691
5.96116	1.746983
6.02963	1.746258
6.09888	1.745515
6.16892	1.744755
6.23977	1.743976
6.31143	1.743179
6.38392	1.742362
6.45724	1.741526
6.5314	1.740669
6.60641	1.739792
6.68229	1.738894
6.75903	1.737974
6.83666	1.737031
6.91518	1.736066
6.9946	1.735077
7.07493	1.734065
7.15619	1.733027
7.23838	1.731964
7.32151	1.730876
7.4056	1.72976
7.49065	1.728617
7.57668	1.727447
7.6637	1.726247
7.75171	1.725018
7.84074	1.723758
7.93079	1.722468
8.02188	1.721145
8.11401	1.71979
8.2072	1.718401
8.30146	1.716978
8.3968	1.715519
8.49323	1.714023
8.59078	1.71249
8.68944	1.710919
8.78924	1.709309
8.89018	1.707657
8.99229	1.705964
9.09556	1.704229
9.20003	1.702449
9.30569	1.700624
9.41256	1.698753
9.52067	1.696834
9.63001	1.694866
9.74061	1.692848
9.85248	1.690777
9.96564	1.688654
10.0801	1.686475
10.1959	1.68424
10.313	1.681947
10.4314	1.679594
10.5512	1.67718
10.6724	1.674703
10.795	1.67216
10.9189	1.669551
11.0443	1.666872
11.1712	1.664123
11.2995	1.6613
11.4293	1.658401
11.5605	1.655425
11.6933	1.652369
11.8276	1.649231
11.9634	1.646007
12.1008	1.642695
12.2398	1.639293
12.3804	1.635798
12.5226	1.632206
12.6664	1.628514
12.8119	1.62472
12.959	1.62082
13.1078	1.616811
13.2584	1.612688
13.4107	1.608448
13.5647	1.604088
13.7205	1.599602
13.878	1.594988
14.0374	1.590239
14.1987	1.585352
14.3617	1.580322
14.5267	1.575144
14.6935	1.569811
14.8623	1.56432
15.033	1.558663
15.2056	1.552835
15.3802	1.546829
15.5569	1.540639
15.7356	1.534257
15.9163	1.527676
16.0991	1.520888
16.284	1.513885
16.471	1.506658
16.6602	1.499198
16.8515	1.491495
17.045	1.483538
17.2408	1.475318
17.4388	1.466822
17.6391	1.458039
17.8417	1.448955
18.0466	1.439556
18.2539	1.429829
18.4635	1.419756
18.6756	1.409323
18.89	1.39851
19.107	1.387299
19.3264	1.375669
19.5484	1.363598
19.7729	1.351062
20	1.338037

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: —

LiBr (Lithium bromide): all datasets

Li 1976: n 0.21–20 µm n 0.21–20 µm default

About LiBr (Lithium bromide)

Lithium bromide (LiBr) is a salt that is most commonly used as a desiccant in air-conditioning systems. It is highly hygroscopic, easily absorbing water from the air. In the realm of optics, it is used less frequently but can serve as a transparent material in the infrared range. LiBr is soluble in water, alcohol, and other polar solvents, and it is generally not suitable for high-power optical applications due to its hygroscopic nature, which can lead to degradation over time when exposed to moisture.

More about LiBr (Lithium bromide) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/LiBr/nk/Li.yml
ID: ds_d564678c98e1
API: /v1/datasets/ds_d564678c98e1

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