Abstract

The ordinary and extraordinary complex refractive indices, n o - jκ o and n e - jκ e, of a nematic liquid crystal were measured in the infrared region at 3.0–11.5-µm wavelength. The complex refractive indices were evaluated in terms of the angular dependence of the reflectance. Semicylindrical CsI prisms and a goniometer were used for measurement of the reflectance in a wide incident-angle range and throughout the wide infrared spectral region. Refractive indices n o and n e changed notably near the absorption wavelength. Negative birefringence, i.e., n e < n o, was observed in the vicinity of 6.6 µm, where n e changed more than did n o.

© 2003 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
  3. R. C. Sharp, D. P. Resler, D. S. Hobbs, T. A. Dorschner, “Electrically tunable liquid-crystal wave plate in the infrared,” Opt. Lett. 15, 87–89 (1990).
    [CrossRef] [PubMed]
  4. J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).
  5. S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
    [CrossRef]
  6. D. B. Chenault, R. A. Chipman, K. M. Johnson, D. Doroski, “Infrared linear diattenuation and birefringence spectra of ferroelectric liquid crystals,” Opt. Lett. 17, 447–449 (1992).
    [CrossRef] [PubMed]
  7. M. Saito, N. Matsumoto, J. Nishimura, “Measurement of the refractive-index spectrum for birefringent and absorptive liquids,” Appl. Opt. 37, 5169–5175 (1998).
    [CrossRef]
  8. Chisso Corporation, Lixon Information, catalog (Chisso Corporation, Chiba, Japan, 1995).
  9. M. Saito, K. Nakajima, M. Shishido, “Polymer coating on infrared silver halide fiber for photo-darkening protection,” J. Lightwave Technol. 20, 441–447 (2002).
    [CrossRef]

2002 (1)

1998 (1)

1996 (1)

J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).

1992 (1)

1990 (1)

1984 (1)

S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
[CrossRef]

1981 (1)

J. G. Pasko, J. Tracy, W. Elser, “Liquid crystal infrared modulation,” Opt. Eng. 20, 970–975 (1981).
[CrossRef]

1978 (1)

A. F. Fray, C. Hilsum, D. Jones, “Some properties of liquid crystals as infrared modulators,” Infrared Phys. 18, 35–41 (1978).
[CrossRef]

Chenault, D. B.

Chipman, R. A.

Doroski, D.

Dorschner, T. A.

Efron, U.

S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
[CrossRef]

Elser, W.

J. G. Pasko, J. Tracy, W. Elser, “Liquid crystal infrared modulation,” Opt. Eng. 20, 970–975 (1981).
[CrossRef]

Fray, A. F.

A. F. Fray, C. Hilsum, D. Jones, “Some properties of liquid crystals as infrared modulators,” Infrared Phys. 18, 35–41 (1978).
[CrossRef]

Hess, L. D.

S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
[CrossRef]

Hilsum, C.

A. F. Fray, C. Hilsum, D. Jones, “Some properties of liquid crystals as infrared modulators,” Infrared Phys. 18, 35–41 (1978).
[CrossRef]

Hobbs, D. S.

Johnson, K. M.

Jones, D.

A. F. Fray, C. Hilsum, D. Jones, “Some properties of liquid crystals as infrared modulators,” Infrared Phys. 18, 35–41 (1978).
[CrossRef]

Kita, J.

J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).

Kobayashi, J.

J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).

Matsumoto, N.

Nakajima, K.

Nishimura, J.

Pasko, J. G.

J. G. Pasko, J. Tracy, W. Elser, “Liquid crystal infrared modulation,” Opt. Eng. 20, 970–975 (1981).
[CrossRef]

Resler, D. P.

Saito, M.

Sharp, R. C.

Shishido, M.

Tracy, J.

J. G. Pasko, J. Tracy, W. Elser, “Liquid crystal infrared modulation,” Opt. Eng. 20, 970–975 (1981).
[CrossRef]

Wu, S. T.

S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
[CrossRef]

Yoshino, K.

J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).

Appl. Opt. (1)

Appl. Phys. Lett. (1)

S. T. Wu, U. Efron, L. D. Hess, “Infrared birefringence of liquid crystals,” Appl. Phys. Lett. 44, 1033–1035 (1984).
[CrossRef]

Infrared Phys. (1)

A. F. Fray, C. Hilsum, D. Jones, “Some properties of liquid crystals as infrared modulators,” Infrared Phys. 18, 35–41 (1978).
[CrossRef]

J. Lightwave Technol. (1)

Opt. Eng. (1)

J. G. Pasko, J. Tracy, W. Elser, “Liquid crystal infrared modulation,” Opt. Eng. 20, 970–975 (1981).
[CrossRef]

Opt. Lett. (2)

Trans. Inst. Electron. Inform. Commun. Eng. C-I (1)

J. Kobayashi, J. Kita, K. Yoshino, “The light-chopper for infrared detection utilizing ferroelectric liquid crystal,” Trans. Inst. Electron. Inform. Commun. Eng. C-I J79, 240–248 (1996).

Other (1)

Chisso Corporation, Lixon Information, catalog (Chisso Corporation, Chiba, Japan, 1995).

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Figures (5)

Fig. 1
Fig. 1

Structure of the liquid-crystal sample cell.

Fig. 2
Fig. 2

Optical system for infrared reflectance measurement: FTIR, Fourier-transform infrared spectrometer.

Fig. 3
Fig. 3

Angular dependence of the reflectance at the CsI-liquid-crystal boundary. Open circles and open triangles, reflected-light intensities I(θ) (left-hand axis) that were measured for s and p polarization, respectively. Their saturation value, I 0 = I(90°), was determined by the least-squares method [Eq. (5)]; then the reflectances (right-hand axis) were determined to be I(θ)/I 0. Curves show the best-fitting theoretical values that were calculated with Eq. (3) or (4). The best-fitting parameters (n o , κ o , n e , and κ e ) are shown in each figure. Measurement wavelengths were (a) 4, (b) 5, and (c) 8 µm.

Fig. 4
Fig. 4

(a) Reflectances at the CsI-air boundary that were measured by use of the semicylindrical CsI prism. Open circles and open triangles, to s and p polarization, respectively. Solid curves, best-fitting theoretical values. Filled circles and filled triangles, reflectances that were measured for the CsI prism with the low-index polyimide coating. (b) Refractive-index (n G ) spectrum of CsI that was determined from the measured reflectances by the least-squares fitting method.

Fig. 5
Fig. 5

Refractive indices (n o , n e ) and extinction coefficients (κ o , κ e ) of the liquid crystal that were evaluated at each wavelength.

Tables (1)

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Table 1 Refractive Indices n and Extinction Coefficients κ for Ordinary or Extraordinary Light

Equations (5)

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Rpθ=no-jκo2 cos θ-nGno-jκo2-nG2 sin2 θ1/2no-jκo2 cos θ+nGno-jκo2-nG2 sin2 θ1/22,
Rsθ=nG cos θ-ne-jκe2-nG2 sin2 θ1/2nG cos θ+ne-jκe2-nG2 sin2 θ1/22
Rpθ¯=Rp+Rp1-Rp2τ2+Rp31-Rp2τ4+Rp51-Rp2τ6+=1+1-2Rpexp-8πκod/λ1-nG2 sin2 θ/no21/21-Rp2 exp-8πκod/λ1-nG2 sin2 θ/no21/2Rp,
Rsθ¯=1+1-2Rsexp-8πκed/λ1-nG2 sin2 θ/ne21/21-Rs2 exp-8πκed/λ1-nG2 sin2 θ/ne21/2Rs.
σ=1Ni=1NRθi¯-Iθi/I021/2,

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