Optical constants

Refractive index of CsBr (Cesium bromide)

Li 1976: n 0.21–55 µm; 20 °C

Data: formula 1
Range: 0.21–55 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.6976
Extinction coefficient k: 0

Permittivity ε₁: 2.88184
Permittivity ε₂: 0

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

Abbe number V_d: 34.186
Chromatic dispersion dn/dλ: -0.103507 µm⁻¹

Group index n_g: 1.75842
Group velocity dispersion: 205.986 fs²/mm

Dispersion parameter D: -1123.77 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

# CsBr (Cesium bromide): Li 1976: n 0.21–55 µm; 20 °C
csbr = ls.fetch_refractiveindex("main", "CsBr", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(csbr.range_nm)  # (210, 55000) nm
eps = csbr.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_382535992434/lightsmith"
csbr = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(csbr.source)  # citation and provenance travel with the data

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

# ... load csbr as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=csbr)],
    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_382535992434/lightsmith?model=drude_lorentz"
csbr_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 = 0.146 + \frac{1.26628 λ^{2}}{λ^{2} - {0.12}^{2}} + \frac{0.01137 λ^{2}}{λ^{2} - {0.146}^{2}} + \frac{0.00975 λ^{2}}{λ^{2} - {0.16}^{2}} + \frac{0.00672 λ^{2}}{λ^{2} - {0.173}^{2}} + \frac{0.34557 λ^{2}}{λ^{2} - {0.187}^{2}} + \frac{3.76339 λ^{2}}{λ^{2} - {136.05}^{2}}

Valid from 0.21 to 55.0 µm.

Coefficients as stored

C_i	Value
C1	0.146
C2	1.26628
C3	0.12
C4	0.01137
C5	0.146
C6	0.00975
C7	0.16
C8	0.00672
C9	0.173
C10	0.34557
C11	0.187
C12	3.76339
C13	136.05

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 is derived by critical analysis of experimental data from several sources.

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

CsBr (Cesium bromide), Li 1976: n 0.21–55 µm; 20 °C: n and k versus wavelength
λ (µm)	n
0.21	2.18206
0.212951	2.138907
0.215944	2.102628
0.218978	2.071569
0.222055	2.044581
0.225176	2.02084
0.22834	1.99974
0.231549	1.980823
0.234803	1.963736
0.238102	1.948201
0.241448	1.933998
0.244841	1.92095
0.248282	1.908909
0.251771	1.897756
0.255309	1.887389
0.258897	1.877724
0.262535	1.868688
0.266224	1.860218
0.269966	1.852262
0.273759	1.844774
0.277606	1.837711
0.281508	1.831039
0.285463	1.824726
0.289475	1.818743
0.293543	1.813067
0.297668	1.807674
0.301851	1.802545
0.306093	1.797661
0.310394	1.793006
0.314756	1.788564
0.319179	1.784324
0.323665	1.780272
0.328213	1.776396
0.332825	1.772687
0.337502	1.769134
0.342245	1.76573
0.347054	1.762465
0.351932	1.759333
0.356877	1.756326
0.361892	1.753438
0.366978	1.750663
0.372135	1.747995
0.377364	1.745428
0.382667	1.742959
0.388045	1.740582
0.393498	1.738293
0.399027	1.736088
0.404635	1.733963
0.410321	1.731915
0.416087	1.72994
0.421934	1.728035
0.427864	1.726197
0.433876	1.724423
0.439973	1.72271
0.446156	1.721056
0.452426	1.719459
0.458784	1.717916
0.465231	1.716426
0.471768	1.714985
0.478398	1.713592
0.485121	1.712245
0.491938	1.710942
0.498851	1.709683
0.505861	1.708464
0.51297	1.707285
0.520179	1.706144
0.527488	1.705039
0.534901	1.70397
0.542418	1.702935
0.55004	1.701932
0.55777	1.700962
0.565608	1.700021
0.573556	1.69911
0.581616	1.698228
0.589789	1.697373
0.598078	1.696544
0.606482	1.695741
0.615005	1.694963
0.623647	1.694208
0.632411	1.693477
0.641298	1.692768
0.65031	1.69208
0.659449	1.691413
0.668716	1.690766
0.678113	1.690139
0.687642	1.689531
0.697306	1.68894
0.707105	1.688368
0.717041	1.687812
0.727118	1.687273
0.737336	1.68675
0.747697	1.686242
0.758204	1.685749
0.768859	1.685271
0.779664	1.684807
0.79062	1.684356
0.80173	1.683919
0.812997	1.683494
0.824421	1.683082
0.836007	1.682681
0.847755	1.682293
0.859668	1.681915
0.871749	1.681548
0.883999	1.681192
0.896422	1.680847
0.909019	1.680511
0.921793	1.680184
0.934746	1.679868
0.947882	1.67956
0.961202	1.679261
0.97471	1.67897
0.988407	1.678688
1.0023	1.678413
1.01638	1.678147
1.03066	1.677888
1.04515	1.677636
1.05984	1.677391
1.07473	1.677153
1.08983	1.676922
1.10515	1.676698
1.12068	1.676479
1.13643	1.676267
1.1524	1.67606
1.16859	1.67586
1.18501	1.675665
1.20166	1.675475
1.21855	1.67529
1.23567	1.675111
1.25304	1.674936
1.27065	1.674767
1.2885	1.674602
1.30661	1.674441
1.32497	1.674285
1.34359	1.674133
1.36247	1.673985
1.38162	1.673841
1.40103	1.673701
1.42072	1.673565
1.44069	1.673432
1.46093	1.673303
1.48146	1.673177
1.50228	1.673055
1.52339	1.672935
1.5448	1.672819
1.56651	1.672706
1.58852	1.672596
1.61084	1.672489
1.63348	1.672384
1.65644	1.672283
1.67971	1.672183
1.70332	1.672086
1.72725	1.671992
1.75153	1.6719
1.77614	1.67181
1.8011	1.671723
1.82641	1.671638
1.85208	1.671554
1.8781	1.671473
1.9045	1.671393
1.93126	1.671316
1.9584	1.67124
1.98592	1.671166
2.01383	1.671094
2.04213	1.671023
2.07082	1.670954
2.09992	1.670887
2.12943	1.670821
2.15936	1.670756
2.1897	1.670692
2.22047	1.67063
2.25168	1.67057
2.28332	1.67051
2.31541	1.670452
2.34794	1.670394
2.38094	1.670338
2.4144	1.670283
2.44832	1.670229
2.48273	1.670175
2.51762	1.670123
2.553	1.670072
2.58887	1.670021
2.62526	1.669971
2.66215	1.669922
2.69956	1.669873
2.73749	1.669825
2.77596	1.669778
2.81497	1.669731
2.85453	1.669685
2.89464	1.66964
2.93532	1.669595
2.97657	1.66955
3.0184	1.669506
3.06082	1.669462
3.10383	1.669418
3.14745	1.669375
3.19168	1.669332
3.23653	1.669289
3.28201	1.669246
3.32813	1.669204
3.3749	1.669162
3.42232	1.66912
3.47042	1.669077
3.51919	1.669035
3.56864	1.668993
3.61879	1.668951
3.66964	1.668909
3.72121	1.668867
3.7735	1.668824
3.82653	1.668782
3.8803	1.668739
3.93483	1.668696
3.99013	1.668652
4.0462	1.668609
4.10306	1.668565
4.16072	1.66852
4.21919	1.668476
4.27848	1.668431
4.3386	1.668385
4.39957	1.668339
4.4614	1.668292
4.52409	1.668245
4.58767	1.668197
4.65214	1.668148
4.71751	1.668099
4.78381	1.668049
4.85103	1.667998
4.9192	1.667947
4.98833	1.667894
5.05843	1.667841
5.12951	1.667787
5.2016	1.667731
5.27469	1.667675
5.34881	1.667618
5.42398	1.667559
5.5002	1.6675
5.57749	1.667439
5.65587	1.667377
5.73535	1.667313
5.81595	1.667248
5.89768	1.667182
5.98056	1.667115
6.0646	1.667046
6.14982	1.666975
6.23624	1.666902
6.32388	1.666828
6.41275	1.666753
6.50286	1.666675
6.59425	1.666596
6.68691	1.666514
6.78088	1.666431
6.87617	1.666346
6.9728	1.666258
7.07079	1.666169
7.17015	1.666077
7.27091	1.665982
7.37309	1.665886
7.4767	1.665787
7.58176	1.665685
7.68831	1.66558
7.79635	1.665473
7.90591	1.665363
8.01701	1.66525
8.12967	1.665135
8.24391	1.665016
8.35976	1.664894
8.47724	1.664768
8.59637	1.664639
8.71717	1.664507
8.83967	1.664371
8.96389	1.664232
9.08985	1.664089
9.21759	1.663941
9.34712	1.66379
9.47847	1.663634
9.61167	1.663475
9.74674	1.66331
9.88371	1.663142
10.0226	1.662968
10.1634	1.66279
10.3063	1.662607
10.4511	1.662418
10.598	1.662225
10.7469	1.662025
10.8979	1.661821
11.0511	1.66161
11.2064	1.661394
11.3638	1.661171
11.5235	1.660942
11.6855	1.660707
11.8497	1.660465
12.0162	1.660216
12.1851	1.65996
12.3563	1.659696
12.5299	1.659426
12.706	1.659147
12.8846	1.65886
13.0656	1.658566
13.2492	1.658262
13.4354	1.65795
13.6242	1.657629
13.8157	1.657299
14.0098	1.656959
14.2067	1.656609
14.4063	1.65625
14.6088	1.65588
14.8141	1.655499
15.0223	1.655107
15.2334	1.654703
15.4474	1.654288
15.6645	1.653861
15.8846	1.653421
16.1079	1.652969
16.3342	1.652503
16.5638	1.652023
16.7965	1.65153
17.0326	1.651022
17.2719	1.650499
17.5146	1.64996
17.7608	1.649406
18.0103	1.648835
18.2634	1.648248
18.5201	1.647643
18.7803	1.64702
19.0443	1.646378
19.3119	1.645717
19.5833	1.645037
19.8585	1.644336
20.1375	1.643615
20.4205	1.642871
20.7075	1.642106
20.9985	1.641317
21.2935	1.640504
21.5928	1.639667
21.8962	1.638805
22.2039	1.637916
22.5159	1.637001
22.8323	1.636057
23.1532	1.635085
23.4786	1.634083
23.8085	1.63305
24.1431	1.631985
24.4824	1.630888
24.8264	1.629757
25.1753	1.62859
25.529	1.627388
25.8878	1.626148
26.2516	1.624869
26.6205	1.62355
26.9946	1.62219
27.3739	1.620786
27.7586	1.619339
28.1487	1.617845
28.5443	1.616304
28.9454	1.614714
29.3521	1.613073
29.7646	1.611379
30.1829	1.60963
30.607	1.607825
31.0371	1.605961
31.4733	1.604036
31.9156	1.602047
32.3641	1.599994
32.8189	1.597872
33.2801	1.59568
33.7478	1.593415
34.222	1.591073
34.7029	1.588653
35.1906	1.586151
35.6851	1.583563
36.1866	1.580886
36.6951	1.578118
37.2107	1.575253
37.7337	1.572289
38.2639	1.569221
38.8016	1.566044
39.3469	1.562754
39.8998	1.559347
40.4605	1.555817
41.0291	1.552159
41.6057	1.548368
42.1903	1.544436
42.7832	1.540359
43.3844	1.536129
43.9941	1.53174
44.6123	1.527184
45.2393	1.522452
45.875	1.517538
46.5197	1.512431
47.1734	1.507122
47.8363	1.501602
48.5085	1.495859
49.1902	1.489882
49.8815	1.483658
50.5824	1.477175
51.2932	1.470418
52.014	1.463372
52.745	1.456022
53.4862	1.448348
54.2378	1.440334
55	1.431957

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: —

CsBr (Cesium bromide): all datasets

About CsBr (Cesium bromide)

Caesium bromide (CsBr) is an ionic compound composed of caesium and bromine atoms in a 1:1 ratio. It forms colorless, hygroscopic crystals and is highly soluble in water. The compound has applications in various fields, including analytical chemistry, where it is used as a scintillation material in scintillation counters. Additionally, it serves as a transparent material in the infrared spectral range, making it useful in infrared optics. CsBr is also utilized in the manufacturing of certain high-performance photodetectors and other optoelectronic devices. Despite its utility, caesium bromide should be handled with care due to the reactivity of caesium and the potential for bromine to form harmful by-products. It can react vigorously with substances like acids and water, so proper safety precautions must be observed during handling and storage. Overall, CsBr is a material of interest for various specialized applications, particularly those involving infrared technology and radiation detection.

Caesium bromide - Wikipedia

More about CsBr (Cesium bromide) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/CsBr/nk/Li.yml
ID: ds_382535992434
API: /v1/datasets/ds_382535992434

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