Optical constants

Refractive index of BGG (barium gallogermanate) glass

Zelmon et al. 2002: n 0.4–5.0 µm

Data: formula 2
Range: 0.4–5 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.75128
Extinction coefficient k: 0

Permittivity ε₁: 3.06698
Permittivity ε₂: 0

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

Abbe number V_d: 37.407
Chromatic dispersion dn/dλ: -0.101952 µm⁻¹

Group index n_g: 1.81119
Group velocity dispersion: 200.023 fs²/mm

Dispersion parameter D: -1091.23 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

# BGG (barium gallogermanate) glass: Zelmon et al. 2002: n 0.4–5.0 µm
bgg = ls.fetch_refractiveindex("glass", "BGG", "Zelmon", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(bgg.range_nm)  # (400, 5000) nm
eps = bgg.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_fb14b9c30d53/lightsmith"
bgg = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(bgg.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (bgg/zelmon-2002).

# ... load bgg as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=bgg)],
    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_fb14b9c30d53/lightsmith?model=drude_lorentz"
bgg_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 (C in µm²) (formula 2), λ in µm

n^{2} - 1 = \frac{0.82725 λ^{2}}{λ^{2} - 0.02978} + \frac{1.14635 λ^{2}}{λ^{2} - 0.005117} + \frac{1.53923 λ^{2}}{λ^{2} - 272.657}

Valid from 0.4 to 5.0 µm.

Coefficients as stored

C_i	Value
C1	0.0
C2	0.82725
C3	0.02978
C4	1.14635
C5	0.005117
C6	1.53923
C7	272.657

Comments and conditions

BaO : Ga₂O₃ : GeO₂ = 42.9 : 17.0 : 40.1.

References

D. E. Zelmon, S. S. Bayya, J. S. Sanghera, I. D. Aggarwal. Dispersion of barium gallogermanate glass. Appl. Opt. 41, 1366 (2002)

doi:10.1364/ao.41.001366 Dispersion of barium gallogermanate glass, Applied Optics (2002)

Cite

David E. Zelmon, Shyam S. Bayya, Jasbinder S. Sanghera and Ishwar D. Aggarwal. Dispersion of barium gallogermanate glass. Applied Optics, 41, 1366 (2002), doi:10.1364/ao.41.001366; 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

BGG (barium gallogermanate) glass, Zelmon et al. 2002: n 0.4–5.0 µm: n and k versus wavelength
λ (µm)	n
0.4	1.788785
0.40254	1.787829
0.405096	1.786889
0.407669	1.785965
0.410258	1.785057
0.412863	1.784163
0.415485	1.783284
0.418123	1.78242
0.420778	1.78157
0.42345	1.780734
0.426139	1.779912
0.428845	1.779103
0.431569	1.778307
0.434309	1.777524
0.437067	1.776754
0.439843	1.775996
0.442636	1.77525
0.445446	1.774516
0.448275	1.773793
0.451122	1.773082
0.453987	1.772382
0.456869	1.771693
0.459771	1.771015
0.46269	1.770348
0.465628	1.76969
0.468585	1.769043
0.471561	1.768406
0.474555	1.767779
0.477569	1.767161
0.480602	1.766553
0.483654	1.765954
0.486725	1.765364
0.489816	1.764783
0.492926	1.764211
0.496056	1.763648
0.499206	1.763093
0.502376	1.762546
0.505567	1.762007
0.508777	1.761476
0.512008	1.760954
0.515259	1.760438
0.518531	1.759931
0.521824	1.759431
0.525138	1.758938
0.528473	1.758453
0.531829	1.757974
0.535206	1.757502
0.538604	1.757038
0.542025	1.75658
0.545467	1.756128
0.548931	1.755683
0.552416	1.755245
0.555924	1.754812
0.559455	1.754386
0.563007	1.753966
0.566582	1.753552
0.57018	1.753143
0.573801	1.752741
0.577445	1.752344
0.581112	1.751953
0.584802	1.751567
0.588516	1.751186
0.592253	1.750811
0.596014	1.750441
0.599799	1.750076
0.603607	1.749716
0.607441	1.749361
0.611298	1.74901
0.61518	1.748665
0.619086	1.748324
0.623018	1.747988
0.626974	1.747657
0.630955	1.74733
0.634962	1.747007
0.638994	1.746689
0.643052	1.746375
0.647136	1.746065
0.651245	1.745759
0.655381	1.745457
0.659542	1.74516
0.663731	1.744866
0.667945	1.744576
0.672187	1.74429
0.676456	1.744007
0.680751	1.743729
0.685074	1.743453
0.689424	1.743182
0.693802	1.742914
0.698208	1.742649
0.702642	1.742388
0.707104	1.74213
0.711594	1.741875
0.716113	1.741624
0.720661	1.741376
0.725237	1.741131
0.729842	1.740889
0.734477	1.74065
0.739141	1.740414
0.743835	1.740181
0.748558	1.739951
0.753312	1.739723
0.758096	1.739499
0.76291	1.739277
0.767754	1.739058
0.77263	1.738841
0.777536	1.738627
0.782474	1.738416
0.787442	1.738207
0.792443	1.738001
0.797475	1.737797
0.802539	1.737596
0.807636	1.737397
0.812764	1.7372
0.817925	1.737006
0.823119	1.736814
0.828346	1.736624
0.833607	1.736436
0.8389	1.73625
0.844227	1.736067
0.849588	1.735886
0.854984	1.735706
0.860413	1.735529
0.865877	1.735353
0.871375	1.73518
0.876909	1.735008
0.882477	1.734839
0.888081	1.734671
0.893721	1.734505
0.899396	1.73434
0.905107	1.734178
0.910855	1.734017
0.916639	1.733858
0.92246	1.733701
0.928318	1.733545
0.934213	1.73339
0.940145	1.733238
0.946115	1.733087
0.952123	1.732937
0.95817	1.732789
0.964254	1.732642
0.970377	1.732497
0.97654	1.732353
0.982741	1.732211
0.988981	1.73207
0.995262	1.73193
1.00158	1.731792
1.00794	1.731655
1.01434	1.731519
1.02078	1.731384
1.02727	1.73125
1.03379	1.731118
1.04035	1.730987
1.04696	1.730857
1.05361	1.730728
1.0603	1.7306
1.06703	1.730474
1.07381	1.730348
1.08063	1.730223
1.08749	1.7301
1.0944	1.729977
1.10135	1.729855
1.10834	1.729735
1.11538	1.729615
1.12246	1.729496
1.12959	1.729378
1.13676	1.72926
1.14398	1.729144
1.15124	1.729028
1.15856	1.728914
1.16591	1.7288
1.17332	1.728686
1.18077	1.728574
1.18827	1.728462
1.19581	1.728351
1.2034	1.72824
1.21105	1.72813
1.21874	1.728021
1.22648	1.727913
1.23426	1.727805
1.2421	1.727697
1.24999	1.72759
1.25793	1.727484
1.26592	1.727378
1.27395	1.727273
1.28204	1.727168
1.29019	1.727064
1.29838	1.72696
1.30662	1.726856
1.31492	1.726753
1.32327	1.726651
1.33167	1.726549
1.34013	1.726447
1.34864	1.726345
1.35721	1.726244
1.36582	1.726143
1.3745	1.726042
1.38323	1.725942
1.39201	1.725842
1.40085	1.725742
1.40974	1.725642
1.4187	1.725543
1.42771	1.725444
1.43677	1.725345
1.4459	1.725246
1.45508	1.725147
1.46432	1.725049
1.47362	1.72495
1.48297	1.724852
1.49239	1.724753
1.50187	1.724655
1.51141	1.724557
1.521	1.724458
1.53066	1.72436
1.54038	1.724262
1.55016	1.724164
1.56001	1.724065
1.56991	1.723967
1.57988	1.723869
1.58992	1.72377
1.60001	1.723671
1.61017	1.723573
1.6204	1.723474
1.63069	1.723375
1.64104	1.723275
1.65146	1.723176
1.66195	1.723076
1.6725	1.722976
1.68313	1.722876
1.69381	1.722776
1.70457	1.722675
1.71539	1.722574
1.72629	1.722473
1.73725	1.722371
1.74828	1.722269
1.75938	1.722167
1.77056	1.722064
1.7818	1.721961
1.79311	1.721858
1.8045	1.721754
1.81596	1.721649
1.82749	1.721544
1.8391	1.721439
1.85078	1.721333
1.86253	1.721226
1.87436	1.721119
1.88626	1.721012
1.89824	1.720904
1.91029	1.720795
1.92242	1.720686
1.93463	1.720576
1.94691	1.720465
1.95928	1.720354
1.97172	1.720242
1.98424	1.720129
1.99684	1.720016
2.00952	1.719901
2.02228	1.719786
2.03512	1.719671
2.04805	1.719554
2.06105	1.719437
2.07414	1.719318
2.08731	1.719199
2.10057	1.719079
2.11391	1.718958
2.12733	1.718836
2.14084	1.718713
2.15443	1.71859
2.16812	1.718465
2.18188	1.718339
2.19574	1.718212
2.20968	1.718084
2.22371	1.717955
2.23784	1.717825
2.25205	1.717693
2.26635	1.717561
2.28074	1.717427
2.29522	1.717292
2.3098	1.717156
2.32447	1.717018
2.33923	1.71688
2.35408	1.71674
2.36903	1.716598
2.38407	1.716456
2.39921	1.716312
2.41445	1.716166
2.42978	1.716019
2.44521	1.715871
2.46074	1.715721
2.47636	1.715569
2.49209	1.715416
2.50792	1.715262
2.52384	1.715106
2.53987	1.714948
2.556	1.714789
2.57223	1.714627
2.58856	1.714465
2.605	1.7143
2.62154	1.714134
2.63819	1.713965
2.65494	1.713795
2.6718	1.713623
2.68877	1.71345
2.70584	1.713274
2.72303	1.713096
2.74032	1.712916
2.75772	1.712735
2.77523	1.712551
2.79286	1.712365
2.81059	1.712177
2.82844	1.711986
2.8464	1.711794
2.86447	1.711599
2.88266	1.711402
2.90097	1.711202
2.91939	1.711001
2.93793	1.710796
2.95659	1.71059
2.97536	1.710381
2.99426	1.710169
3.01327	1.709955
3.03241	1.709738
3.05166	1.709518
3.07104	1.709296
3.09054	1.709071
3.11017	1.708843
3.12992	1.708613
3.14979	1.708379
3.1698	1.708143
3.18993	1.707903
3.21018	1.707661
3.23057	1.707415
3.25108	1.707167
3.27173	1.706915
3.2925	1.70666
3.31341	1.706402
3.33445	1.70614
3.35563	1.705875
3.37694	1.705606
3.39838	1.705334
3.41996	1.705059
3.44168	1.70478
3.46353	1.704497
3.48553	1.70421
3.50766	1.70392
3.52994	1.703626
3.55235	1.703328
3.57491	1.703026
3.59761	1.70272
3.62046	1.702409
3.64345	1.702095
3.66658	1.701776
3.68987	1.701453
3.7133	1.701126
3.73688	1.700794
3.76061	1.700458
3.78449	1.700117
3.80852	1.699771
3.83271	1.699421
3.85705	1.699065
3.88154	1.698705
3.90619	1.69834
3.93099	1.69797
3.95596	1.697594
3.98108	1.697213
4.00636	1.696827
4.0318	1.696436
4.0574	1.696039
4.08317	1.695636
4.1091	1.695228
4.13519	1.694814
4.16145	1.694394
4.18788	1.693968
4.21447	1.693535
4.24123	1.693097
4.26817	1.692652
4.29527	1.692201
4.32255	1.691743
4.34999	1.691279
4.37762	1.690808
4.40542	1.69033
4.43339	1.689845
4.46155	1.689353
4.48988	1.688853
4.51839	1.688347
4.54708	1.687832
4.57596	1.68731
4.60502	1.686781
4.63426	1.686243
4.66369	1.685697
4.6933	1.685143
4.72311	1.684581
4.7531	1.68401
4.78328	1.683431
4.81366	1.682843
4.84422	1.682246
4.87499	1.681639
4.90594	1.681024
4.9371	1.680399
4.96845	1.679764
5	1.679119

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: —

BGG (barium gallogermanate) glass: all datasets

Zelmon et al. 2002: n 0.4–5.0 µm n 0.4–5 µm default

About BGG (barium gallogermanate) glass

BGG glass, a member of the heavy crown glass family, is distinguished by its high refractive index and moderate optical dispersion. These characteristics make it an appealing choice for specialized optical systems that demand precise control over chromatic aberrations or a specific focal length. Due to its high refractive index, BGG glass enables the design of shorter focal lengths or smaller optical elements, potentially leading to more compact and lightweight optical systems. Commonly found in the catalogs of industry standards like Schott Glass, the BGG classification serves as a shorthand to convey key optical properties of the glass. As such, BGG glass is often employed in high-end camera lenses, scientific instruments, and other applications requiring exceptional optical performance. Its unique attributes make it an invaluable resource for optical designers striving for excellence in imaging and light manipulation. Composition: BaO : Ga₂O₃ : GeO₂

More about BGG (barium gallogermanate) glass →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/glass/misc/BGG/nk/Zelmon.yml
ID: ds_fb14b9c30d53
API: /v1/datasets/ds_fb14b9c30d53

Plot