Optical constants

Refractive index of BK7G18 (SCHOTT)

BK7G18: n,k 0.38–2.5 µm

Data
formula 2 + tabulated k
Range
0.38–2.5 µm
Temperature
293 K
Licence
CC0-1.0

Plot

Click the plot to set the calculator wavelength.

At one wavelength

Range 0.38–2.5 µm
Refractive index n
1.51975
Extinction coefficient k
3.77863e-08
Permittivity ε1
2.30963
Permittivity ε2
1.14851e-07
Absorption coefficient α
0.00808095 cm⁻¹
Penetration depth δ = λ/(2πk)
2.47496e+09 nm
Abbe number Vd
63.584
Chromatic dispersion dn/dλ
-0.0423749 µm⁻¹
Group index ng
1.54465
Group velocity dispersion
71.6812 fs²/mm
Dispersion parameter D
-391.059 ps/(nm·km)
Photon energy
2.11001 eV

ε = (n + ik)², α = 4πk/λ, ng = 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

# BK7G18 (SCHOTT): BK7G18
schott_bk7g18 = ls.fetch_refractiveindex("specs", "SCHOTT-optical", "BK7G18", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(schott_bk7g18.range_nm)  # (380, 2500) nm
eps = schott_bk7g18.eps([633])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

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
n2−1=1.26538542λ2λ2−0.00813104078+0.0144191073λ2λ2−0.0543303226+1.00323028λ2λ2−102.821166

Valid from 0.38 to 2.5 µm.

Coefficients as stored
CiValue
C10.0
C21.26538542
C30.00813104078
C40.0144191073
C50.0543303226
C61.00323028
C7102.821166

Comments and conditions

inquiry glass

Conditions

temperature
293 K

Properties

thermal dispersion
type: formula A, coefficients: 1.52e-06 1.37e-08 -1.26e-11 4.36e-07 4.17e-10 0.194
nd
1.51975
Vd
63.58
glass code
520636.252
glass status
special
density
value: 2520
thermal expansion
value: 7e-06, temperature range: 243 343; value: 8.22e-06, temperature range: 293 573
dPgF
0.0007
resistance
acid: 1.0; stain: 0.0; alkali: 2.0

Thermo-optic coefficient

  • Schott thermal-dispersion model (reference temperature 293.0 K): dn/dT = 1.17e-06 K⁻¹ at 633 nm, dn/dT = 7.50e-07 K⁻¹ at 1310 nm, dn/dT = 7.14e-07 K⁻¹ at 1550 nm

References

Cite

SCHOTT Zemax catalog 2017-01-20b (obtained from http://www.schott.com); See also SCHOTT glass data sheets; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

Computed on 416 wavelengths, the same grid as the API and the library
BK7G18 (SCHOTT), BK7G18: n and k versus wavelength
λ (µm)nk
0.381.5370743.055100e-06
0.3817981.5367822.789871e-06
0.3836051.5364952.523386e-06
0.3854211.536212.255640e-06
0.3872451.5359291.986628e-06
0.3890781.535651.716342e-06
0.391.5355121.580300e-06
0.3909191.5353751.513864e-06
0.3927691.5351031.380109e-06
0.3946281.5348341.245720e-06
0.3964951.5345681.110696e-06
0.3983721.5343059.750319e-07
0.41.5340818.573300e-07
0.4002571.5340458.470988e-07
0.4021521.5337887.717823e-07
0.4040551.5335346.961092e-07
0.4051.5334096.585300e-07
0.4059671.5332826.374885e-07
0.4078881.5330335.956861e-07
0.4098191.5327875.536858e-07
0.4117581.5325435.114868e-07
0.4137071.5323034.690881e-07
0.4156651.5320644.264887e-07
0.4176321.5318283.836877e-07
0.4196091.5315953.406841e-07
0.421.5315493.321700e-07
0.4215951.5313643.178510e-07
0.423591.5311362.999336e-07
0.4255951.530912.819313e-07
0.4276091.5306872.638439e-07
0.4296321.5304652.456709e-07
0.4316661.5302462.274118e-07
0.4337091.530032.090663e-07
0.4357611.5298161.906341e-07
0.4361.5297911.884900e-07
0.4378241.5296031.826015e-07
0.4398961.5293931.759104e-07
0.4419771.5291861.691877e-07
0.4440691.528981.624332e-07
0.4461711.5287761.556467e-07
0.4482821.5285751.488280e-07
0.4504041.5283751.419771e-07
0.4525361.5281781.350938e-07
0.4546771.5279831.281779e-07
0.4568291.5277891.212293e-07
0.4589911.5275981.142478e-07
0.461.5275091.109900e-07
0.4611631.5274081.097964e-07
0.4633461.527221.075573e-07
0.4655391.5270341.053075e-07
0.4677421.526851.030471e-07
0.4699561.5266681.007760e-07
0.472181.5264889.849415e-08
0.4744141.5263099.620149e-08
0.476661.5261329.389799e-08
0.4789161.5259579.158358e-08
0.4811821.5257848.925822e-08
0.4834591.5256128.692186e-08
0.4857471.5254428.457444e-08
0.4880461.5252738.221591e-08
0.4903561.5251077.984622e-08
0.4926771.5249417.746531e-08
0.4950081.5247787.507313e-08
0.4973511.5246167.266964e-08
0.4997051.5244557.025477e-08
0.51.5244356.995200e-08
0.502071.5242966.894490e-08
0.5044461.5241386.778876e-08
0.5068331.5239826.662715e-08
0.5092321.5238286.546004e-08
0.5116421.5236756.428741e-08
0.5140631.5235236.310923e-08
0.5164961.5233726.192547e-08
0.5189411.5232246.073611e-08
0.5213971.5230765.954112e-08
0.5238641.522935.834048e-08
0.5263441.5227855.713415e-08
0.5288351.5226415.592212e-08
0.5313371.5224995.470435e-08
0.5338521.5223585.348081e-08
0.5363781.5222185.225149e-08
0.5389171.522085.101634e-08
0.5414681.5219434.977536e-08
0.544031.5218074.852849e-08
0.5461.5217044.757000e-08
0.5466051.5216724.742081e-08
0.5491921.5215384.678269e-08
0.5517911.5214064.614154e-08
0.5544021.5212754.549736e-08
0.5570261.5211454.485013e-08
0.5596621.5210164.419984e-08
0.5623111.5208884.354647e-08
0.5649721.5207614.289001e-08
0.5676461.5206364.223045e-08
0.5703321.5205114.156776e-08
0.5730321.5203884.090193e-08
0.5757441.5202654.023295e-08
0.5784681.5201443.956081e-08
0.581.5200763.918300e-08
0.5812061.5200233.896135e-08
0.5839571.5199043.845585e-08
0.586721.5197863.794796e-08
0.5894971.5196683.743766e-08
0.5922871.5195523.692495e-08
0.595091.5194363.640981e-08
0.5979061.5193223.589224e-08
0.6007361.5192083.537221e-08
0.6035791.5190963.484973e-08
0.6064361.5189843.432477e-08
0.6093061.5188733.379732e-08
0.6121891.5187633.326738e-08
0.6150871.5186543.273493e-08
0.6179981.5185463.219997e-08
0.621.5184723.183200e-08
0.6209231.5184383.168281e-08
0.6238611.5183323.120756e-08
0.6268141.5182263.073007e-08
0.629781.5181213.025031e-08
0.6327611.5180172.976828e-08
0.6357551.5179142.928398e-08
0.6387641.5178122.879738e-08
0.6417871.517712.830847e-08
0.6448251.5176092.781726e-08
0.6478761.5175092.732371e-08
0.6509421.5174092.682784e-08
0.6540231.5173112.632961e-08
0.6571181.5172132.582903e-08
0.661.5171222.536300e-08
0.6602281.5171152.530758e-08
0.6633531.5170192.454900e-08
0.6664921.5169232.378682e-08
0.6696471.5168282.302104e-08
0.6728161.5167332.225164e-08
0.6761.5166392.147859e-08
0.6791991.5165462.070189e-08
0.6824141.5164531.992151e-08
0.6856431.5163621.913744e-08
0.6888881.516271.834965e-08
0.6921491.516181.755814e-08
0.6954241.5160891.676288e-08
0.6987151.5161.596386e-08
0.71.5159651.565200e-08
0.7020221.5159111.560202e-08
0.7053451.5158231.551991e-08
0.7086831.5157351.543741e-08
0.7120371.5156481.535452e-08
0.7154071.5155611.527124e-08
0.7187921.5154751.518756e-08
0.7221941.515391.510349e-08
0.7256121.5153051.501902e-08
0.7290461.515221.493415e-08
0.7324961.5151361.484888e-08
0.7359631.5150531.476320e-08
0.7394461.514971.467712e-08
0.7429461.5148871.459063e-08
0.7464621.5148051.450374e-08
0.7499951.5147241.441643e-08
0.7535441.5146431.432870e-08
0.757111.5145621.424057e-08
0.7606931.5144821.415201e-08
0.7642931.5144021.406304e-08
0.7679111.5143231.397365e-08
0.7715451.5142441.388383e-08
0.7751961.5141651.379359e-08
0.7788651.5140871.370292e-08
0.7825511.514011.361182e-08
0.7862551.5139321.352029e-08
0.7899761.5138551.342832e-08
0.7937141.5137791.333592e-08
0.7974711.5137031.324309e-08
0.8012451.5136271.314981e-08
0.8050371.5135511.305610e-08
0.8088471.5134761.296194e-08
0.8126751.5134021.286733e-08
0.8165211.5133271.277228e-08
0.8203851.5132531.267678e-08
0.8242681.5131791.258082e-08
0.8281691.5131061.248441e-08
0.8320881.5130331.238755e-08
0.8360261.512961.229022e-08
0.8399831.5128871.219244e-08
0.8439581.5128151.209419e-08
0.8479531.5127431.199548e-08
0.8519661.5126711.189630e-08
0.8559981.51261.179665e-08
0.8600491.5125291.169653e-08
0.8641191.5124581.159593e-08
0.8682091.5123871.149486e-08
0.8723181.5123161.139331e-08
0.8764461.5122461.129128e-08
0.8805941.5121761.118877e-08
0.8847611.5121061.108577e-08
0.8889491.5120371.098229e-08
0.8931561.5119671.087831e-08
0.8973831.5118981.077385e-08
0.901631.5118291.066889e-08
0.9058971.511761.056343e-08
0.9101841.5116911.045747e-08
0.9144921.5116231.035101e-08
0.918821.5115541.024405e-08
0.9231681.5114861.013658e-08
0.9275371.5114181.002861e-08
0.9319271.511359.920118e-09
0.9363371.5112829.811116e-09
0.9407691.5112159.701599e-09
0.9452211.5111479.591563e-09
0.9496951.511089.481007e-09
0.9541891.5110139.369927e-09
0.9587051.5109459.258322e-09
0.9632421.5108789.146188e-09
0.9678011.5108119.033524e-09
0.9723811.5107448.920326e-09
0.9769831.5106778.806593e-09
0.9816071.5106118.692321e-09
0.9862521.5105448.577509e-09
0.990921.5104778.462154e-09
0.995611.5104118.346252e-09
1.000321.5103448.229802e-09
1.005061.5102788.112801e-09
1.009811.5102117.995246e-09
1.014591.5101457.877134e-09
1.019391.5100787.758464e-09
1.024221.5100127.639232e-09
1.029061.5099457.519436e-09
1.033941.5098797.399073e-09
1.038831.5098137.278140e-09
1.043741.5097467.156635e-09
1.048681.509687.034555e-09
1.053651.5096136.911897e-09
1.058631.5095476.788658e-09
1.061.5095296.754900e-09
1.063641.509487.503937e-09
1.068681.5094148.538611e-09
1.073741.5093479.578181e-09
1.078821.509281.062267e-08
1.083921.5092141.167211e-08
1.089051.5091471.272651e-08
1.094211.509081.378590e-08
1.099391.5090131.485030e-08
1.104591.5089461.591974e-08
1.109821.5088791.699424e-08
1.115071.5088121.807383e-08
1.120351.5087441.915853e-08
1.125651.5086772.024836e-08
1.130981.5086092.134335e-08
1.136331.5085422.244352e-08
1.141711.5084742.354890e-08
1.147111.5084062.465950e-08
1.152541.5083382.577537e-08
1.157991.5082692.689652e-08
1.163471.5082012.802297e-08
1.168981.5081322.915475e-08
1.174511.5080643.029189e-08
1.180071.5079953.143441e-08
1.185651.5079263.258234e-08
1.191271.5078563.373570e-08
1.19691.5077873.489452e-08
1.202571.5077173.605882e-08
1.208261.5076473.722864e-08
1.213981.5075773.840399e-08
1.219721.5075073.958490e-08
1.22551.5074364.077140e-08
1.23131.5073654.196352e-08
1.237121.5072944.316128e-08
1.242981.5072234.436471e-08
1.248861.5071514.557383e-08
1.254771.5070794.678867e-08
1.260711.5070074.800927e-08
1.266681.5069354.923564e-08
1.272671.5068625.046782e-08
1.278691.5067895.170582e-08
1.284751.5067165.294969e-08
1.290831.5066425.419944e-08
1.296931.5065685.545511e-08
1.303071.5064945.671672e-08
1.309241.5064195.798430e-08
1.315441.5063455.925788e-08
1.321661.5062696.053749e-08
1.327921.5061946.182315e-08
1.33421.5061186.311490e-08
1.340521.5060416.441276e-08
1.346861.5059656.571676e-08
1.353231.5058886.702694e-08
1.359641.505816.834331e-08
1.366071.5057326.966592e-08
1.372541.5056547.099478e-08
1.379031.5055757.232993e-08
1.385561.5054967.367141e-08
1.392121.5054177.501923e-08
1.398711.5053377.637343e-08
1.405331.5052567.773404e-08
1.411981.5051767.910109e-08
1.418661.5050948.047460e-08
1.425371.5050128.185462e-08
1.432121.504938.324117e-08
1.43891.5048478.463428e-08
1.445711.5047648.603399e-08
1.452551.504688.744032e-08
1.459421.5045968.885330e-08
1.466331.5045129.027297e-08
1.473271.5044269.169937e-08
1.480241.504349.313251e-08
1.487251.5042549.457243e-08
1.494291.5041679.601917e-08
1.501361.504089.747276e-08
1.508461.5039929.893322e-08
1.51561.5039031.004006e-07
1.522771.5038141.018749e-07
1.529981.5037241.033562e-07
1.531.5037241.033600e-07
1.537221.5036341.194881e-07
1.54451.5035431.357338e-07
1.551811.5034511.520564e-07
1.559151.5033591.684563e-07
1.566531.5032661.849338e-07
1.573941.5031722.014892e-07
1.581391.5030782.181230e-07
1.588881.5029832.348356e-07
1.59641.5028882.516272e-07
1.603951.5027912.684983e-07
1.611541.5026942.854492e-07
1.619171.5025973.024804e-07
1.626831.5024983.195921e-07
1.634531.5023993.367849e-07
1.642271.5022993.540590e-07
1.650041.5021993.714149e-07
1.657851.5020973.888529e-07
1.66571.5019954.063734e-07
1.673581.5018924.239769e-07
1.68151.5017894.416636e-07
1.689461.5016844.594341e-07
1.697451.5015794.772887e-07
1.705491.5014734.952277e-07
1.713561.5013665.132517e-07
1.721671.5012585.313610e-07
1.729811.5011495.495560e-07
1.7381.5010395.678371e-07
1.746231.5009295.862047e-07
1.754491.5008186.046592e-07
1.762791.5007056.232011e-07
1.771141.5005926.418307e-07
1.779521.5004786.605485e-07
1.787941.5003636.793549e-07
1.79641.5002476.982502e-07
1.80491.500137.172350e-07
1.813451.5000127.363097e-07
1.822031.4998937.554746e-07
1.830651.4997737.747302e-07
1.839321.4996527.940770e-07
1.848021.499538.135153e-07
1.856771.4994078.330456e-07
1.865551.4992838.526684e-07
1.874381.4991588.723840e-07
1.883251.4990328.921929e-07
1.892171.4989049.120956e-07
1.901121.4987769.320925e-07
1.910121.4986469.521840e-07
1.919161.4985159.723705e-07
1.928241.4983839.926527e-07
1.937371.498251.013031e-06
1.946541.4981161.033505e-06
1.955751.4979811.054077e-06
1.9651.4978441.074746e-06
1.971.497771.085900e-06
1.97431.4977061.128027e-06
1.983651.4975671.219472e-06
1.993041.4974261.311349e-06
2.002471.4972851.403661e-06
2.011951.4971421.496411e-06
2.021471.4969971.589599e-06
2.031031.4968521.683228e-06
2.040651.4967051.777300e-06
2.05031.4965561.871817e-06
2.060011.4964071.966782e-06
2.069761.4962562.062196e-06
2.079551.4961032.158061e-06
2.089391.4959492.254381e-06
2.099281.4957942.351156e-06
2.109221.4956372.448389e-06
2.11921.4954792.546083e-06
2.129231.4953192.644238e-06
2.139311.4951572.742859e-06
2.149431.4949942.841946e-06
2.15961.494832.941502e-06
2.169821.4946643.041529e-06
2.180091.4944963.142029e-06
2.190411.4943273.243005e-06
2.200781.4941563.344459e-06
2.211191.4939843.446394e-06
2.221661.4938093.548810e-06
2.232171.4936333.651711e-06
2.242741.4934563.755100e-06
2.253351.4932763.858977e-06
2.264011.4930953.963346e-06
2.274731.4929124.068210e-06
2.285491.4927284.173569e-06
2.296311.4925414.279427e-06
2.307181.4923534.385786e-06
2.31811.4921624.492649e-06
2.3251.4920414.560200e-06
2.329071.491974.664982e-06
2.340091.4917764.948869e-06
2.351171.491585.234100e-06
2.362291.4913825.520681e-06
2.373471.4911825.808618e-06
2.384711.490986.097918e-06
2.395991.4907766.388587e-06
2.407331.4905696.680632e-06
2.418721.4903616.974059e-06
2.430171.4901517.268874e-06
2.441671.4899387.565085e-06
2.453231.4897237.862698e-06
2.464841.4895078.161719e-06
2.47651.4892878.462155e-06
2.488221.4890668.764013e-06
2.51.4888429.067300e-06

Optical transmission calculator

Free-standing sample in vacuum, normal incidence
Method
Transmittance T
—
Reflectance R
—

Fresnel reflection calculator

Direction
Rp
—
Rs
—
R = (Rp+Rs)/2
—
Phase φp
—
Phase φs
—
Brewster angle θB
—
Critical angle θC
—