Abstract

Silicon beam splitters several millimeters thick offer numerous advantages over thin freestanding dielectric beam splitters. For routine spectroscopy for which resolutions of better than 1cm1 are not required, a silicon beam splitter can replace several Mylar beam splitters to span the entire far-infrared region. In addition to superior long-wavelength performance that extends well into the terahertz region, the silicon beam splitter has the additional advantage that its efficiency displays little polarization dependence.

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References

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  1. J. L. Deuzé and A. L. Fymat, "Instrumentation optimization in Fourier spectroscopy. 1: Far infrared beam splitters," Appl. Opt. 13, 1807-1813 (1974).
    [CrossRef] [PubMed]
  2. D. R. Smith and E. V. Loewenstein, "Far-infrared thin-film beam splitters: calculated properties," Appl. Opt. 14, 2473-2475 (1975).
    [CrossRef] [PubMed]
  3. G. Kampffmeyer and A. Pfeil, "Self-supporting thin-film beam splitter for far-infared interferometers," Appl. Phys. A 14, 313-317 (1977).
  4. D. R. Smith and E. V. Loewenstein, "Optical constants of far infrared materials. 3: Plastics," Appl. Opt. 14, 1335-1341 (1975).
    [CrossRef] [PubMed]
  5. D. Labrie, I. Booth, M. L. W. Thewalt, and B. P. Clayman, "Use of polypropylene film for infrared cryostat windows," Appl. Opt. 25, 171-172 (1986).
    [CrossRef] [PubMed]
  6. L. Genzel and J. Kuhl, "Tilt-compensated Michelson interferometer for Fourier transform spectroscopy," Appl. Opt. 17, 3304-3008 (1978).
    [CrossRef] [PubMed]
  7. R. J. Bell, Introductory Fourier Transform Spectroscopy (Academic, 1972).
  8. D. A. Naylor, R. T. Boreiko, and T. A. Clark, "Mylar beam splitter efficiency in far infrared interferometers: angle of incidence and absorption effects," Appl. Opt. 17, 1055-1058 (1978).
    [CrossRef] [PubMed]
  9. D. F. Edwards, "Silicon (Si)," in Handbook of Optical Constants of Solids, E. D. Palik, ed. (Academic, 1985), pp. 547-569.
  10. R. F. Potter, "Germanium (Ge)," in Handbook of Optical Constants of Solids, E. D. Palik, ed. (Academic, 1985), pp. 465-478.
  11. K. E. Kornelsen, M. Dressel, J. E. Eldridge, M. J. Brett, and K. L. Westra, "Far-infrared optical absorption and reflectivity of a superconducting NbN film," Phys. Rev. B 44, 11882-11887 (1991).
    [CrossRef]
  12. D. W. Vidrine and C. R. Anderson, "Silicon beamsplitter," U.S. patent 4,632,553 (30 December 1986).
  13. J. A. Dobrowolski and W. A. Traub, "New designs for far-infrared beam splitters," Appl. Opt. 35, 2934-2946 (1996).
    [CrossRef] [PubMed]
  14. N. L. Rowell and E. A. Wang, "Bilayer free-standing beam splitter for Fourier transform infrared spectrometry," Appl. Opt. 35, 2927-2933 (1996).
    [CrossRef] [PubMed]
  15. N. L. Rowell and E. A. Wang, "Silicon coated mylar beamsplitter," U.S. patent 5,558,934 (24 September 1996).
  16. Bruker Optik GmbH, Rudolf-Plank-Strasse 27, Ettlingen, Germany.

1996 (2)

1991 (1)

K. E. Kornelsen, M. Dressel, J. E. Eldridge, M. J. Brett, and K. L. Westra, "Far-infrared optical absorption and reflectivity of a superconducting NbN film," Phys. Rev. B 44, 11882-11887 (1991).
[CrossRef]

1986 (1)

1978 (2)

1977 (1)

G. Kampffmeyer and A. Pfeil, "Self-supporting thin-film beam splitter for far-infared interferometers," Appl. Phys. A 14, 313-317 (1977).

1975 (2)

1974 (1)

Appl. Opt. (8)

Appl. Phys. A (1)

G. Kampffmeyer and A. Pfeil, "Self-supporting thin-film beam splitter for far-infared interferometers," Appl. Phys. A 14, 313-317 (1977).

Phys. Rev. B (1)

K. E. Kornelsen, M. Dressel, J. E. Eldridge, M. J. Brett, and K. L. Westra, "Far-infrared optical absorption and reflectivity of a superconducting NbN film," Phys. Rev. B 44, 11882-11887 (1991).
[CrossRef]

Other (6)

D. W. Vidrine and C. R. Anderson, "Silicon beamsplitter," U.S. patent 4,632,553 (30 December 1986).

N. L. Rowell and E. A. Wang, "Silicon coated mylar beamsplitter," U.S. patent 5,558,934 (24 September 1996).

Bruker Optik GmbH, Rudolf-Plank-Strasse 27, Ettlingen, Germany.

D. F. Edwards, "Silicon (Si)," in Handbook of Optical Constants of Solids, E. D. Palik, ed. (Academic, 1985), pp. 547-569.

R. F. Potter, "Germanium (Ge)," in Handbook of Optical Constants of Solids, E. D. Palik, ed. (Academic, 1985), pp. 465-478.

R. J. Bell, Introductory Fourier Transform Spectroscopy (Academic, 1972).

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Figures (4)

Fig. 1
Fig. 1

Beam splitter efficiency versus frequency in a standard Michelson spectrometer ( θ i = 45 ° ) of 3.5, 6, 12, and 23 μ m PET beam splitters as a function of frequency for s-polarized radiation.

Fig. 2
Fig. 2

Variation of R 0 for s- and p-polarized radiation as a function of the refractive index for 45° (solid curve), 30° (long dashed curve), and 15° (short dashed curve) angles of incidence. The values of the refractive index for both PET and Si are indicated. Note that, for a high-index material such as Si, not only are the values for R 0 closer to the ideal value, but the difference between R 0 s and R 0 p is much smaller at a reduced angle of incidence (15°) than in a conventional Michelson spectrometer (45°).

Fig. 3
Fig. 3

Experimentally observed ratio of two unpolarized single-channel spectra using a silicon beam splitter in a Genzel-type interferometer ( θ i 15 ° ) with resolutions of 0.03 and 1 cm 1 , shown over a narrow frequency interval in the far infrared. (b) The calculated beam splitter efficiency for a thick piece of silicon ( d 2.7   mm , n 3.4 ) for s- and p-polarized radiation (solid and dashed curves, respectively). The almost structureless horizontal lines drawn with a lighter weight are the result of smoothing the data by use of a Gaussian convolution with a width of 1 cm 1 ; the solid and dashed curves again denote the s and p polarizations, respectively.

Fig. 4
Fig. 4

(a) Comparison of the single-channel spectra for a Si (solid curve) and 3.5 μ m PET (dashed curve) beam splitter in a Genzel interferometer spanning much of the far-infrared region (GLOBAR source, liquid helium bolometer detector). The experimental resolution is 2 cm 1 . (b) Comparison of the single-channel spectra for a Si (solid curve) and 50 μ m PET (dashed curve) beam splitter (Hg arc lamp source, liquid helium bolometer detector with a 100 cm 1 low-pass cold filter). The experimental resolution is 1 cm 1 . The weak interference fringes observed at low frequency are due to an intrinsic detector effect.

Tables (1)

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Table 1 Efficiencies for a PET Beam Splitter ( n = 1.6) and for a Si Beam Splitter ( n = 3.4) a

Equations (4)

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R 0 = 2 R 2 ( 1 cos   δ ) 1 + R 2 2 R   cos   δ ,
T 0 = ( 1 R 2 ) 1 + R 2 2 R   cos   δ ,
R p = tan 2 ( θ i θ t ) tan 2 ( θ i + θ t ) ,
R s = sin 2 ( θ i θ t ) sin 2 ( θ i + θ t ) ,

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