Optical constants

Refractive index of KCl (Potassium chloride)

Li 1976: n 0.18–35 µm

Data: formula 1
Range: 0.18–35 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.49037
Extinction coefficient k: 0

Permittivity ε₁: 2.2212
Permittivity ε₂: 0

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

Abbe number V_d: 44.388
Chromatic dispersion dn/dλ: -0.0562544 µm⁻¹

Group index n_g: 1.52342
Group velocity dispersion: 109.9 fs²/mm

Dispersion parameter D: -599.561 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

# KCl (Potassium chloride): Li 1976: n 0.18–35 µm
kcl = ls.fetch_refractiveindex("main", "KCl", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(kcl.range_nm)  # (180, 35000) nm
eps = kcl.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_4e9b682a8f89/lightsmith"
kcl = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(kcl.source)  # citation and provenance travel with the data

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

# ... load kcl as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=kcl)],
    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_4e9b682a8f89/lightsmith?model=drude_lorentz"
kcl_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 = 0.26486 + \frac{0.30523 λ^{2}}{λ^{2} - {0.1}^{2}} + \frac{0.4162 λ^{2}}{λ^{2} - {0.131}^{2}} + \frac{0.1887 λ^{2}}{λ^{2} - {0.162}^{2}} + \frac{2.62 λ^{2}}{λ^{2} - {70.42}^{2}}

Valid from 0.18 to 35.0 µm.

Coefficients as stored

C_i	Value
C1	0.26486
C2	0.30523
C3	0.1
C4	0.4162
C5	0.131
C6	0.1887
C7	0.162
C8	2.62
C9	70.42

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

KCl (Potassium chloride), Li 1976: n 0.18–35 µm: n and k versus wavelength
λ (µm)	n
0.18	1.893248
0.182393	1.858689
0.184818	1.829566
0.187276	1.80456
0.189766	1.782768
0.192289	1.763543
0.194846	1.746413
0.197436	1.731019
0.200061	1.717087
0.202721	1.704399
0.205417	1.692783
0.208148	1.682098
0.210915	1.67223
0.21372	1.663084
0.216561	1.654577
0.219441	1.646644
0.222359	1.639226
0.225315	1.632273
0.228311	1.625741
0.231346	1.619594
0.234422	1.613797
0.237539	1.608322
0.240698	1.603143
0.243898	1.598238
0.247141	1.593584
0.250427	1.589165
0.253756	1.584964
0.25713	1.580964
0.260549	1.577154
0.264013	1.57352
0.267524	1.570052
0.271081	1.566739
0.274685	1.563571
0.278337	1.56054
0.282038	1.557638
0.285788	1.554858
0.289588	1.552193
0.293438	1.549637
0.29734	1.547183
0.301293	1.544827
0.305299	1.542563
0.309358	1.540386
0.313472	1.538293
0.31764	1.53628
0.321863	1.534341
0.326142	1.532475
0.330479	1.530676
0.334873	1.528944
0.339325	1.527273
0.343837	1.525662
0.348409	1.524108
0.353041	1.522608
0.357735	1.521161
0.362492	1.519763
0.367311	1.518413
0.372195	1.517108
0.377144	1.515848
0.382158	1.51463
0.387239	1.513452
0.392388	1.512313
0.397605	1.511211
0.402892	1.510145
0.408249	1.509114
0.413677	1.508116
0.419177	1.507149
0.424751	1.506213
0.430398	1.505307
0.436121	1.50443
0.441919	1.503579
0.447795	1.502755
0.453749	1.501957
0.459782	1.501183
0.465895	1.500433
0.47209	1.499706
0.478367	1.499001
0.484727	1.498317
0.491172	1.497654
0.497703	1.497011
0.50432	1.496387
0.511025	1.495781
0.51782	1.495194
0.524705	1.494623
0.531681	1.49407
0.538751	1.493533
0.545914	1.493011
0.553172	1.492505
0.560527	1.492013
0.56798	1.491535
0.575532	1.491072
0.583184	1.490621
0.590938	1.490184
0.598795	1.489759
0.606757	1.489346
0.614824	1.488945
0.622999	1.488555
0.631283	1.488176
0.639676	1.487808
0.648181	1.48745
0.656799	1.487102
0.665532	1.486764
0.674381	1.486435
0.683348	1.486115
0.692434	1.485804
0.70164	1.485502
0.710969	1.485208
0.720422	1.484922
0.730001	1.484644
0.739707	1.484374
0.749542	1.484111
0.759508	1.483855
0.769607	1.483606
0.779839	1.483364
0.790208	1.483128
0.800715	1.482898
0.811361	1.482675
0.822149	1.482458
0.83308	1.482246
0.844157	1.48204
0.855381	1.48184
0.866754	1.481645
0.878278	1.481455
0.889956	1.481269
0.901789	1.481089
0.913779	1.480914
0.925928	1.480743
0.93824	1.480576
0.950714	1.480414
0.963355	1.480256
0.976164	1.480102
0.989143	1.479951
1.00229	1.479805
1.01562	1.479662
1.02912	1.479523
1.04281	1.479388
1.05667	1.479256
1.07072	1.479127
1.08496	1.479001
1.09938	1.478878
1.114	1.478758
1.12881	1.478642
1.14382	1.478528
1.15903	1.478416
1.17444	1.478308
1.19006	1.478202
1.20588	1.478098
1.22191	1.477997
1.23816	1.477898
1.25462	1.477801
1.2713	1.477707
1.28821	1.477614
1.30533	1.477524
1.32269	1.477436
1.34028	1.477349
1.3581	1.477265
1.37615	1.477182
1.39445	1.477101
1.41299	1.477022
1.43178	1.476944
1.45082	1.476868
1.47011	1.476793
1.48965	1.47672
1.50946	1.476648
1.52953	1.476577
1.54987	1.476508
1.57047	1.47644
1.59135	1.476373
1.61251	1.476307
1.63395	1.476243
1.65568	1.476179
1.67769	1.476116
1.7	1.476055
1.7226	1.475994
1.74551	1.475934
1.76871	1.475875
1.79223	1.475817
1.81606	1.475759
1.84021	1.475702
1.86467	1.475646
1.88947	1.475591
1.91459	1.475536
1.94005	1.475481
1.96584	1.475427
1.99198	1.475374
2.01846	1.475321
2.0453	1.475268
2.0725	1.475215
2.10005	1.475163
2.12797	1.475112
2.15627	1.47506
2.18494	1.475009
2.21399	1.474957
2.24342	1.474906
2.27325	1.474855
2.30348	1.474805
2.33411	1.474754
2.36514	1.474703
2.39659	1.474652
2.42845	1.474601
2.46074	1.474549
2.49346	1.474498
2.52661	1.474447
2.56021	1.474395
2.59425	1.474343
2.62874	1.47429
2.66369	1.474238
2.69911	1.474184
2.73499	1.474131
2.77136	1.474077
2.80821	1.474022
2.84554	1.473967
2.88338	1.473912
2.92172	1.473856
2.96056	1.473799
2.99993	1.473741
3.03981	1.473683
3.08023	1.473624
3.12119	1.473564
3.16269	1.473503
3.20474	1.473442
3.24735	1.473379
3.29052	1.473315
3.33427	1.473251
3.37861	1.473185
3.42353	1.473118
3.46905	1.47305
3.51517	1.472981
3.56191	1.472911
3.60927	1.472839
3.65726	1.472765
3.70589	1.472691
3.75516	1.472615
3.80509	1.472537
3.85568	1.472458
3.90695	1.472377
3.95889	1.472294
4.01153	1.47221
4.06487	1.472124
4.11891	1.472036
4.17368	1.471946
4.22917	1.471854
4.2854	1.47176
4.34238	1.471664
4.40012	1.471565
4.45862	1.471464
4.5179	1.471361
4.57797	1.471256
4.63884	1.471148
4.70052	1.471037
4.76302	1.470924
4.82635	1.470808
4.89052	1.470689
4.95554	1.470567
5.02143	1.470443
5.0882	1.470315
5.15585	1.470184
5.2244	1.470049
5.29387	1.469912
5.36425	1.46977
5.43558	1.469626
5.50785	1.469477
5.58108	1.469325
5.65529	1.469169
5.73048	1.469009
5.80667	1.468844
5.88388	1.468676
5.96211	1.468503
6.04138	1.468325
6.12171	1.468143
6.2031	1.467956
6.28558	1.467764
6.36915	1.467567
6.45383	1.467365
6.53965	1.467158
6.6266	1.466945
6.7147	1.466726
6.80398	1.466502
6.89445	1.466272
6.98612	1.466035
7.079	1.465792
7.17313	1.465542
7.2685	1.465286
7.36514	1.465023
7.46307	1.464753
7.5623	1.464475
7.66285	1.46419
7.76473	1.463897
7.86797	1.463597
7.97258	1.463287
8.07859	1.46297
8.186	1.462644
8.29484	1.462309
8.40513	1.461964
8.51688	1.461611
8.63013	1.461247
8.74487	1.460874
8.86114	1.46049
8.97896	1.460095
9.09835	1.45969
9.21932	1.459273
9.3419	1.458845
9.46611	1.458405
9.59197	1.457953
9.7195	1.457488
9.84873	1.457009
9.97968	1.456518
10.1124	1.456013
10.2468	1.455493
10.3831	1.454959
10.5211	1.45441
10.661	1.453845
10.8028	1.453264
10.9464	1.452667
11.0919	1.452053
11.2394	1.451421
11.3889	1.450772
11.5403	1.450103
11.6937	1.449416
11.8492	1.448709
12.0067	1.447981
12.1664	1.447232
12.3282	1.446462
12.4921	1.44567
12.6582	1.444854
12.8265	1.444015
12.997	1.443151
13.1698	1.442262
13.3449	1.441347
13.5224	1.440405
13.7021	1.439435
13.8843	1.438437
14.0689	1.437408
14.256	1.43635
14.4455	1.43526
14.6376	1.434137
14.8322	1.43298
15.0294	1.431789
15.2293	1.430561
15.4318	1.429297
15.6369	1.427994
15.8449	1.426651
16.0555	1.425267
16.269	1.423841
16.4853	1.42237
16.7045	1.420854
16.9266	1.419291
17.1517	1.417679
17.3797	1.416017
17.6108	1.414302
17.8449	1.412533
18.0822	1.410707
18.3226	1.408823
18.5663	1.406879
18.8131	1.404872
19.0632	1.4028
19.3167	1.40066
19.5735	1.398451
19.8338	1.396168
20.0975	1.39381
20.3647	1.391373
20.6355	1.388854
20.9099	1.38625
21.1879	1.383557
21.4696	1.380773
21.7551	1.377892
22.0443	1.374912
22.3374	1.371827
22.6344	1.368634
22.9354	1.365328
23.2403	1.361903
23.5493	1.358354
23.8624	1.354677
24.1797	1.350865
24.5012	1.346911
24.827	1.34281
25.1571	1.338554
25.4915	1.334136
25.8305	1.329548
26.1739	1.324781
26.5219	1.319828
26.8746	1.314677
27.2319	1.309319
27.594	1.303744
27.9609	1.297938
28.3326	1.291891
28.7093	1.285587
29.0911	1.279014
29.4778	1.272155
29.8698	1.264993
30.2669	1.257511
30.6694	1.249689
31.0771	1.241505
31.4903	1.232936
31.909	1.223958
32.3333	1.214541
32.7632	1.204657
33.1988	1.194272
33.6402	1.18335
34.0875	1.171851
34.5407	1.159729
35	1.146936

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: —

KCl (Potassium chloride): all datasets

About KCl (Potassium chloride)

Potassium chloride (KCl) is a salt that finds use in various optical applications due to its wide spectral transmission range. Like its bromide counterpart, potassium chloride is hygroscopic, requiring cautious handling and storage conditions to preserve its optical qualities. It is commonly used as a prismatic or plane-parallel component in infrared spectroscopy, particularly because of its low cost and good transmission in the mid and far-infrared regions. Additionally, it serves as a substrate for specialized optical coatings. Due to its moisture sensitivity, it's less suitable for applications exposed to high humidity or varying environmental conditions. Nonetheless, KCl remains an important material in the toolkit of optical engineers and scientists.

Potassium chloride - Wikipedia

More about KCl (Potassium chloride) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/KCl/nk/Li.yml
ID: ds_4e9b682a8f89
API: /v1/datasets/ds_4e9b682a8f89

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