Optical constants

Refractive index of GeS₂ (Germanium disulfide)

Slavich et al. 1989: n,k(α) 0.299–2.04 µm

Data: tabulated nk
Range: 0.2994–2.042 µm
Points: 31
Optical axis: alpha
Licence: CC0-1.0

Biaxial crystal, axes: alpha

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 2.34458
Extinction coefficient k: 0.0174226

Permittivity ε₁: 5.49676
Permittivity ε₂: 0.0816977

Absorption coefficient α: 3725.99 cm⁻¹
Penetration depth δ = λ/(2πk): 5367.69 nm

Abbe number V_d: —
Chromatic dispersion dn/dλ: -0.832377 µm⁻¹

Group index n_g: 2.83369
Group velocity dispersion: — fs²/mm

Dispersion parameter D: — 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

# GeS2 (Germanium disulfide): Slavich et al. 1989: n,k(α) 0.299–2.04 µm
ges2 = ls.fetch_refractiveindex("main", "GeS2", "Slavich-abinitio-α", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(ges2.range_nm)  # (299.45, 2042.16) nm
eps = ges2.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_827b74ba96cc/lightsmith"
ges2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(ges2.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (ges2/slavich-1989-abinitio).

# ... load ges2 as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=ges2)],
    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"]).

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.

Comments and conditions

n(α),k(α). Ab initio calculations.

Conditions

direction: alpha

References

A. S. Slavich, G. A. Ermolaev, I. A. Zavidovskiy, D. V. Grudinin, K. V. Kravtsov, M. K. Tatmyshevskiy, M. S. Mironov, A. N. Toksumakov, G. I. Tselikov, I. M. Fradkin, K. V. Voronin, M. R. Povolotskiy, O. G. Matveeva, A. V. Syuy, D. I. Yakubovsky, D. M. Tsymbarenko, I. Kruglov, D. A. Ghazaryan, S. M. Novikov, A. A. Vyshnevyy, A. V. Arsenin, V. S. Volkov, K. S. Novoselov. Germanium disulfide as an alternative high refractive index and transparent material for UV-visible nanophotonics. Light Sci. Appl., 14, 213 (2025) (Numerical data kindly provided by Dr. Georgy Ermolaev)

doi:10.1038/s41377-025-01886-y Germanium disulfide as an alternative high refractive index and transparent material for UV-visible nanophotonics, Light: Science & Applications (2025)

Cite

Aleksandr S. Slavich et al.. Germanium disulfide as an alternative high refractive index and transparent material for UV-visible nanophotonics. Light: Science & Applications, 14, 213 (2025), doi:10.1038/s41377-025-01886-y; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

31 rows as published

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

GeS2 (Germanium disulfide), Slavich et al. 1989: n,k(α) 0.299–2.04 µm: n and k versus wavelength
λ (µm)	n	k
0.29945	2.55637	0.69286
0.30785	2.58063	0.6358
0.31676	2.58019	0.59149
0.32624	2.58244	0.55893
0.33633	2.58415	0.52129
0.34711	2.57824	0.5028
0.35864	2.62256	0.48901
0.371	2.65148	0.41537
0.38431	2.66194	0.35305
0.39862	2.66394	0.27016
0.41412	2.63032	0.18188
0.43091	2.56275	0.1229
0.44916	2.50293	0.11037
0.46913	2.47936	0.10678
0.49099	2.46654	0.0789
0.51506	2.43378	0.04355
0.5417	2.39234	0.02608
0.5713	2.35815	0.01919
0.60441	2.33059	0.0156
0.64169	2.3075	0.01317
0.68395	2.28771	0.01134
0.73234	2.27048	0.00989
0.78815	2.25541	0.00867
0.85329	2.24215	0.0076
0.93037	2.23046	0.00668
1.02293	2.22019	0.00586
1.13605	2.2112	0.00511
1.27756	2.20337	0.00443
1.45951	2.19664	0.00378
1.70213	2.19089	0.00317
2.04216	2.18614	0.00261

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: —

GeS₂ (Germanium disulfide): all datasets

Experimental data

Ab initio calculations

About GeS2 (Germanium disulfide)

Germanium disulfide (GeS₂) is a chalcogenide compound known for its wide infrared transparency and high refractive index. It crystallizes in an orthorhombic structure but is often used in its amorphous (glassy) form. GeS₂-based glasses are key materials in infrared optics, especially in mid-IR applications (2–10 µm), due to their low phonon energy and favorable nonlinear optical properties. These characteristics make GeS₂ a valuable component in optical fibers, lenses, and infrared sensors. It is also studied for its role in photonics, infrared transmitting windows, and as a host material in rare-earth-doped fiber amplifiers.

More about GeS2 (Germanium disulfide) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/GeS2/nk/Slavich-abinitio-alpha.yml
ID: ds_827b74ba96cc
API: /v1/datasets/ds_827b74ba96cc

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