# this file is part of refractiveindex.info database
# refractiveindex.info database is in the public domain
# copyright and related rights waived via CC0 1.0

REFERENCES: |
    Crystran Ltd.
    <a href="https://issuu.com/crystran/docs/handbook_2023_website">
    The Crystran handbook of infra-red and ultra-violet optical materials (5th edition, 2023)
    </a><br>
    See also
    <a href="https://www.crystran.com/optical-materials/germanium-ge">
    Crystran Ge online data sheet
    </a>
COMMENTS: |
    Germanium is a high index material that is used to manufacture Attenuated Total Reflection (ATR) prisms for spectroscopy. Its refractive index is such that Germanium makes an effective natural 50% beamsplitter without the need for coatings. Germanium is also used extensively as a substrate for production of optical filters. Germanium covers the whole of the 8-14 micron thermal band and is used in lens systems for thermal imaging. Germanium can be AR coated with Diamond producing an extremely tough front optic.<br>
    Germanium is grown using the Czochralski technique by a small number of manufacturers in Belgium, USA, China and Russia. The refractive index of Germanium changes rapidly with temperature and the material becomes opaque at all wavelengths a little above 350K as the band gap floods with thermal electrons.<br>
    REFERENCES:<br>
    (1) Handbook Optical Constants, ed Palik, V1, ISBN 0-12-544420-6<br>
    (2) Li, Refractive Index of Germanium etc, J.Phys Chem, V9, p561, 1980<br>
    (3) Pearson & Brattain, Proc. Inst. Radio Eng. V43, p1794, 1955
    (4) Fine, J.App.Phys, V24, p338, 1953<br>
    (5) Wortman & Evans, V36, (1), P153 (1965)<br>
    (6) Hawkins, Sherwood, Djotni: Mid IR Filters for astronomical and remote sensing instrumentation. Invited Paper SPIE Conference Glasgow 2008<br>
    (7) Manufactures Published Data
PROPERTIES:
    density:
      - value: 5330
    thermal_dispersion:
      - type: constant
        value: 396e-06
    thermal_expansion:
      - temperature: 298
        value: 6.1e-06
    hardness:
      - type: Knoop
        value: 7.65e9
    melting_point:
      - value: 1209
    thermal_conductivity:
      - temperature: 293
        value: 58.62
    youngs_modulus:
      - value: 102.7e9
    poissons_ratio:
      - value: 0.28
    solubility:
      - value: 0
DATA:
  - type: tabulated n
    data: |
        2.058 4.1020
        2.153 4.0919
        2.313 4.0786
        2.437 4.0708
        2.577 4.0609
        2.714 4.0562
        2.998 4.0452
        3.303 4.0369
        4.258 4.0216
        4.866 4.0170
        6.238 4.0094
        8.660 4.0043
        9.720 4.0034
        11.04 4.0026
        12.00 4.0023
        13.02 4.0021
  - type: tabulated k
    data: |
        1.70 3.76E-04
        1.75 2.90E-04
        1.80 1.34E-04
        1.85 5.35E-05
        1.90 2.21E-05
        1.95 1.31E-06
        2.00 0.00E+00
        2.05 0.00E+00
        2.10 0.00E+00
        2.15 0.00E+00
        2.20 0.00E+00
        2.25 0.00E+00
        2.30 0.00E+00
        2.35 0.00E+00
        2.40 0.00E+00
        2.45 0.00E+00
        2.50 0.00E+00
        2.55 0.00E+00
        2.60 0.00E+00
        2.65 0.00E+00
        2.70 0.00E+00
        2.75 0.00E+00
        2.80 0.00E+00
        2.85 0.00E+00
        2.90 0.00E+00
        2.95 0.00E+00
        3.00 0.00E+00
        3.05 0.00E+00
        3.10 0.00E+00
        3.15 0.00E+00
        3.20 0.00E+00
        3.25 0.00E+00
        3.30 0.00E+00
        3.35 0.00E+00
        3.40 0.00E+00
        3.45 0.00E+00
        3.50 0.00E+00
        3.55 0.00E+00
        3.60 0.00E+00
        3.65 0.00E+00
        3.70 0.00E+00
        3.75 0.00E+00
        3.80 0.00E+00
        3.85 0.00E+00
        3.90 0.00E+00
        3.95 0.00E+00
        4.00 0.00E+00
        4.05 0.00E+00
        4.10 0.00E+00
        4.15 0.00E+00
        4.20 0.00E+00
        4.25 0.00E+00
        4.30 0.00E+00
        4.35 0.00E+00
        4.40 0.00E+00
        4.45 0.00E+00
        4.50 0.00E+00
        4.55 0.00E+00
        4.60 0.00E+00
        4.65 0.00E+00
        4.70 0.00E+00
        4.75 0.00E+00
        4.80 0.00E+00
        4.85 0.00E+00
        4.90 0.00E+00
        4.95 0.00E+00
        5.00 0.00E+00
        5.05 0.00E+00
        5.10 0.00E+00
        5.15 0.00E+00
        5.20 0.00E+00
        5.25 0.00E+00
        5.30 0.00E+00
        5.35 0.00E+00
        5.40 0.00E+00
        5.45 0.00E+00
        5.50 0.00E+00
        5.55 0.00E+00
        5.60 0.00E+00
        5.65 0.00E+00
        5.70 0.00E+00
        5.75 0.00E+00
        5.80 0.00E+00
        5.85 0.00E+00
        5.90 0.00E+00
        5.95 0.00E+00
        6.00 0.00E+00
        6.05 0.00E+00
        6.10 0.00E+00
        6.15 0.00E+00
        6.20 0.00E+00
        6.25 0.00E+00
        6.30 0.00E+00
        6.35 0.00E+00
        6.40 0.00E+00
        6.45 0.00E+00
        6.50 0.00E+00
        6.55 0.00E+00
        6.60 0.00E+00
        6.65 2.54E-08
        6.70 7.24E-08
        6.75 1.29E-07
        6.80 1.77E-07
        6.85 2.34E-07
        6.90 2.92E-07
        6.95 3.50E-07
        7.00 4.19E-07
        7.05 4.97E-07
        7.10 6.31E-07
        7.15 7.96E-07
        7.20 8.96E-07
        7.25 9.60E-07
        7.30 1.02E-06
        7.35 1.08E-06
        7.40 1.14E-06
        7.45 1.18E-06
        7.50 1.22E-06
        7.55 1.27E-06
        7.60 1.30E-06
        7.65 1.34E-06
        7.70 1.38E-06
        7.75 1.42E-06
        7.80 1.45E-06
        7.85 1.47E-06
        7.90 1.50E-06
        7.95 1.53E-06
        8.00 1.55E-06
        8.05 1.58E-06
        8.10 1.59E-06
        8.15 1.60E-06
        8.20 1.61E-06
        8.25 1.62E-06
        8.30 1.61E-06
        8.35 1.60E-06
        8.40 1.59E-06
        8.45 1.58E-06
        8.50 1.55E-06
        8.55 1.52E-06
        8.60 1.49E-06
        8.65 1.45E-06
        8.70 1.41E-06
        8.75 1.37E-06
        8.80 1.32E-06
        8.85 1.27E-06
        8.90 1.23E-06
        8.95 1.18E-06
        9.00 1.15E-06
        9.05 1.10E-06
        9.10 1.07E-06
        9.15 1.02E-06
        9.20 9.82E-07
        9.25 9.33E-07
        9.30 8.84E-07
        9.35 8.34E-07
        9.40 7.95E-07
        9.45 7.93E-07
        9.50 8.53E-07
        9.55 9.88E-07
        9.60 1.16E-06
        9.65 1.29E-06
        9.70 1.38E-06
        9.75 1.44E-06
        9.80 1.49E-06
        9.85 1.53E-06
        9.90 1.56E-06
        9.95 1.58E-06
        10.00 1.58E-06
        10.05 1.60E-06
        10.10 1.61E-06
        10.15 1.62E-06
        10.20 1.64E-06
        10.25 1.66E-06
        10.30 1.69E-06
        10.35 1.72E-06
        10.40 1.74E-06
        10.45 1.79E-06
        10.50 1.81E-06
        10.55 1.85E-06
        10.60 1.90E-06
        10.65 1.94E-06
        10.70 1.98E-06
        10.75 2.04E-06
        10.80 2.08E-06
        10.85 2.14E-06
        10.90 2.19E-06
        10.95 2.26E-06
        11.00 2.35E-06
        11.05 2.47E-06
        11.10 2.63E-06
        11.15 2.82E-06
        11.20 3.09E-06
        11.25 3.40E-06
        11.30 3.81E-06
        11.35 4.34E-06
        11.40 5.03E-06
        11.45 5.95E-06
        11.50 7.18E-06
        11.55 9.45E-06
        11.60 1.37E-05
        11.65 1.85E-05
        11.70 2.26E-05
        11.75 2.70E-05
        11.80 3.23E-05
        11.85 3.65E-05
        11.90 3.57E-05
        11.95 3.54E-05
        12.00 3.38E-05
        12.05 3.05E-05
        12.10 2.85E-05
        12.15 2.75E-05
        12.20 2.73E-05
        12.25 2.74E-05
        12.30 2.73E-05
        12.35 2.72E-05
        12.40 2.70E-05
        12.45 2.69E-05
        12.50 2.69E-05
        12.55 2.74E-05
        12.60 2.82E-05
        12.65 2.74E-05
        12.70 2.63E-05
        12.75 2.53E-05
        12.80 2.49E-05
        12.85 2.53E-05
        12.90 2.66E-05
        12.95 2.84E-05
        13.00 3.04E-05
        13.05 3.28E-05
        13.10 3.56E-05
        13.15 3.89E-05
        13.20 4.25E-05
        13.25 4.48E-05
        13.30 4.54E-05
        13.35 4.55E-05
        13.40 4.51E-05
        13.45 4.41E-05
        13.50 4.22E-05
        13.55 4.02E-05
        13.60 3.83E-05
        13.65 3.66E-05
        13.70 3.51E-05
        13.75 3.37E-05
        13.80 3.26E-05
        13.85 3.16E-05
        13.90 3.08E-05
        13.95 3.01E-05
        14.00 2.94E-05
        14.05 2.88E-05
        14.10 2.83E-05
        14.15 2.81E-05
        14.20 2.83E-05
        14.25 2.91E-05
        14.30 3.04E-05
        14.35 3.22E-05
        14.40 3.46E-05
        14.45 3.82E-05
        14.50 4.29E-05
        14.55 4.80E-05
        14.60 5.32E-05
        14.65 5.85E-05
        14.70 6.39E-05
        14.75 6.94E-05
        14.80 7.49E-05
        14.85 8.04E-05
        14.90 8.61E-05
        14.95 9.19E-05
        15.00 9.79E-05
        15.05 1.04E-04
        15.10 1.11E-04
        15.15 1.18E-04
        15.20 1.25E-04
        15.25 1.32E-04
        15.30 1.39E-04
        15.35 1.45E-04
        15.40 1.51E-04
        15.45 1.53E-04
        15.50 1.54E-04
        15.55 1.54E-04
        15.60 1.53E-04
        15.65 1.52E-04
        15.70 1.49E-04
        15.75 1.44E-04
        15.80 1.39E-04
        15.85 1.34E-04
        15.90 1.30E-04
        15.95 1.26E-04
        16.00 1.21E-04
        16.05 1.16E-04
        16.10 1.10E-04
        16.15 1.05E-04
        16.20 9.96E-05
        16.25 9.52E-05
        16.30 9.27E-05
        16.35 9.16E-05
        16.40 9.06E-05
        16.45 8.98E-05
        16.50 8.99E-05
        16.55 9.15E-05
        16.60 9.56E-05
        16.65 1.02E-04
        16.70 1.11E-04
        16.75 1.20E-04
        16.80 1.33E-04
        16.85 1.49E-04
        16.90 1.69E-04
        16.95 1.89E-04
        17.00 2.09E-04
        17.05 2.30E-04
        17.10 2.51E-04
        17.15 2.73E-04
        17.20 2.97E-04
        17.25 3.23E-04
        17.30 3.50E-04
        17.35 3.78E-04
        17.40 4.08E-04
        17.45 4.40E-04
        17.50 4.71E-04
        17.55 4.98E-04
        17.60 5.20E-04
        17.65 5.37E-04
        17.70 5.51E-04
        17.75 5.64E-04
        17.80 5.70E-04
        17.85 5.73E-04
        17.90 5.73E-04
        17.95 5.71E-04
        18.00 5.63E-04
        18.05 5.53E-04
        18.10 5.46E-04
        18.15 5.42E-04
        18.20 5.38E-04
        18.25 5.39E-04
        18.30 5.42E-04
        18.35 5.46E-04
        18.40 5.51E-04
        18.45 5.57E-04
        18.50 5.66E-04
        18.55 5.75E-04
        18.60 5.85E-04
        18.65 5.96E-04
        18.70 6.06E-04
        18.75 6.16E-04
        18.80 6.27E-04
        18.85 6.39E-04
        18.90 6.52E-04
        18.95 6.64E-04
        19.00 6.73E-04
        19.05 6.79E-04
        19.10 6.84E-04
        19.15 6.87E-04
        19.20 6.90E-04
        19.25 6.90E-04
        19.30 6.88E-04
        19.35 6.83E-04
        19.40 6.77E-04
        19.45 6.71E-04
        19.50 6.65E-04
        19.55 6.59E-04
        19.60 6.53E-04
        19.65 6.46E-04
        19.70 6.37E-04
        19.75 6.28E-04
        19.80 6.20E-04
        19.85 6.12E-04
        19.90 6.04E-04
        19.95 5.95E-04
        20.00 5.83E-04
        20.05 5.71E-04
        20.10 5.58E-04
        20.15 5.45E-04
        20.20 5.34E-04
        20.25 5.24E-04
        20.30 5.15E-04
        20.35 5.08E-04
        20.40 5.04E-04
        20.45 5.02E-04
        20.50 5.04E-04
        20.55 5.08E-04
        20.60 5.13E-04
        20.65 5.20E-04
        20.70 5.29E-04
        20.75 5.42E-04
        20.80 5.57E-04
        20.85 5.72E-04
        20.90 5.88E-04
        20.95 6.03E-04
        21.00 6.19E-04
        21.05 6.35E-04
        21.10 6.49E-04
        21.15 6.59E-04
        21.20 6.66E-04
        21.25 6.73E-04
        21.30 6.79E-04
        21.35 6.85E-04
        21.40 6.92E-04
        21.45 7.03E-04
        21.50 7.23E-04
        21.55 7.56E-04
        21.60 8.03E-04
        21.65 8.54E-04
        21.70 8.96E-04
        21.75 9.26E-04
        21.80 9.51E-04
        21.85 9.73E-04
        21.90 9.95E-04
        21.95 1.02E-03
        22.00 1.04E-03
        22.05 1.06E-03
        22.10 1.09E-03
        22.15 1.11E-03
        22.20 1.14E-03
        22.25 1.17E-03
        22.30 1.19E-03
        22.35 1.22E-03
        22.40 1.25E-03
        22.45 1.28E-03
        22.50 1.31E-03
        22.55 1.34E-03
        22.60 1.36E-03
        22.65 1.39E-03
        22.70 1.42E-03
        22.75 1.45E-03
        22.80 1.49E-03
        22.85 1.53E-03
        22.90 1.57E-03
        22.95 1.63E-03
        23.00 1.68E-03
        23.05 1.73E-03
        23.10 1.79E-03
        23.15 1.84E-03
        23.20 1.91E-03
        23.25 1.98E-03
        23.30 2.07E-03
        23.35 2.16E-03
        23.40 2.26E-03
        23.45 2.37E-03
        23.50 2.50E-03
        23.55 2.61E-03
        23.60 2.69E-03
        23.65 2.74E-03
        23.70 2.76E-03
        23.75 2.73E-03
        23.80 2.70E-03
        23.85 2.65E-03
        23.90 2.60E-03
        23.95 2.54E-03
        24.00 2.47E-03
        24.05 2.40E-03
        24.10 2.32E-03
        24.15 2.24E-03
        24.20 2.16E-03
        24.25 2.08E-03
        24.30 1.98E-03
        24.35 1.87E-03
        24.40 1.76E-03
        24.45 1.64E-03
        24.50 1.52E-03
        24.55 1.43E-03
        24.60 1.37E-03
        24.65 1.33E-03
        24.70 1.31E-03
        24.75 1.31E-03
        24.80 1.33E-03
        24.85 1.35E-03
        24.90 1.37E-03
        24.95 1.40E-03
        25.00 1.43E-03