Abstract

We report on a first experimental study of the molecular properties of nematic liquid crystals in the terahertz range. In the beginning, we extract the frequency and temperature dependent refractive index and absorption coefficient of the cyanobiphenyls 5CB, 6CB and 7CB from terahertz time domain spectroscopy measurements and investigate the impact of the alkyl chain length on the macroscopic liquid crystal characteristics, focusing especially on the pronounced odd and even effect. Next, we deduce the principle polarizabilities and the order parameter S by applying Vuks’ approximation and Haller’s approach. On this basis, we calculate the main polarizabilities along the longitudinal and transverse axis and link the observed terahertz properties to the molecular structure of the liquid crystals.

© 2010 Optical Society of America

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  8. R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
    [CrossRef]
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  10. H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  44. A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982).
    [CrossRef]
  45. J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
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2009

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

M. Scheller, C. Jansen, and M. Koch, "Analyzing sub-100-μm samples with transmission terahertz time domain spectroscopy," Opt. Commun. 282(7), 1304-1306 (2009).
[CrossRef]

R. Wilk, N. Vieweg, O. Kopschinski, and M. Koch, "Liquid crystal based electrically switchable Bragg structure for THz waves," Opt. Express 17(9), 7377-7382 (2009).
[CrossRef] [PubMed]

2008

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, "Impact of the contact metallization on the performance of photoconductive THz antennas," Opt. Express 16(24), 19695-19705 (2008).
[CrossRef] [PubMed]

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

2006

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

M. I. Capar and E. Cebe, "Molecular dynamic study of the odd-even effect in some 4-n-alkyl-4′-cyanobiphenyls," Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 73(6), 061711 (2006).
[CrossRef] [PubMed]

2004

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

F. Yang and J. R. Sambles, "Microwave liquid-crystal variable phase grating," Appl. Phys. Lett. 85(11), 2041-2043 (2004).
[CrossRef]

J. Li, and S. T. Wu, "Extended Cauchy equations for the refractive indices of liquid crystals," J. Appl. Phys. 95(3), 896-901 (2004).
[CrossRef]

J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004).
[CrossRef]

2003

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

2001

D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001).
[CrossRef]

1999

S. Urban, A. Würflinger, and B. Gestblom, "On the derivation of the nematic order parameter from the dielectric relaxation times," Phys. Chem. Chem. Phys. 1(11), 2787-2791 (1999).
[CrossRef]

1998

S. T. Wu, "Absorption measurements of liquid crystals in the ultraviolet, visible, and infrared," J. Appl. Phys. 84(8), 4462-4465 (1998).
[CrossRef]

1997

Y. N. Murthy and V. R. Murthy, "Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals," Cryst. Res. Technol. 32(7), 999-1005 (1997).
[CrossRef]

T. Nose, S. Sato, K. Mizuno, J. Bae, and T. Nozokido, "Refractive index of nematic liquid crystals in the submillimeter wave region," Appl. Opt. 36(25), 6383-6387 (1997).
[CrossRef]

1996

1993

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

1987

R. S. McEwen, "Instrument Science and Technology," J. Phys. E Sci. Instrum. 20(4), 364-377 (1987).
[CrossRef]

1986

S. T. Wu, "Birefringence dispersions of liquid crystals," Phys. Rev. A 33(2), 1270-1274 (1986).
[CrossRef] [PubMed]

1984

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

1982

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982).
[CrossRef]

1978

R. G. Horn, "Refractive indices and order parameters of two liquid crystals," J. Phys. 39, 105-109 (1978).
[CrossRef]

1975

I. Haller, "Thermodynamic and static properties of liquid crystals," Solid-State Chemistry 10, 103-118 (1975).
[CrossRef]

1974

S. Marčelja, "Chain ordering in liquid crystals. I. Even-odd effect," J. Chem. Phys. 60(9), 3599-3604 (1974).
[CrossRef]

E. P. Raynes and I. A. Shanks, "Fast-Switching Twisted Nematic Electro-Optical Shutter and Colour Filter," Electron. Lett. 10(7), 114-115 (1974).
[CrossRef]

1973

G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973).
[CrossRef]

M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973).
[CrossRef]

1971

M. Schadt and W. Helfrich, "Voltage-Dependent Optical Activity of a Twisted Nematic Liquid Crystal," Appl. Phys. Lett. 18(4), 127-128 (1971).
[CrossRef]

1969

S. Chandrasekhar, and N. V. Madhusudana, "Orientational Order in p-Azoxyanisole, p-Azoxyphenetole and their mixtures in the nematic phase," J. Phys. Colloq. 30(C4), C4-24 (1969).
[CrossRef]

1966

M. F. Vuks, "Determination of the Optical Anisotropy of Aromatic Molecules from the Double Refraction of Crystals," Opt. Spektrosk. 20, 644-651 (1966).

1959

W. Maier, and A. Saupe, Z. Naturforsch. B 14a, 882 (1959).

1889

O. Lehmann, "Über fliessende Krystalle," Z. Phys. Chem. 4, 462-472 (1889).

1888

F. Reinitzer, "Beiträge zur Kenntniss des Cholesterins," Monatsh. Chem. 9(1), 421-441 (1888).
[CrossRef]

Abdoh, M. M. M.

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

Bae, J.

Blumstein, R. B.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Buka, A.

A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982).
[CrossRef]

Capar, M. I.

M. I. Capar and E. Cebe, "Molecular dynamic study of the odd-even effect in some 4-n-alkyl-4′-cyanobiphenyls," Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 73(6), 061711 (2006).
[CrossRef] [PubMed]

Cebe, E.

M. I. Capar and E. Cebe, "Molecular dynamic study of the odd-even effect in some 4-n-alkyl-4′-cyanobiphenyls," Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 73(6), 061711 (2006).
[CrossRef] [PubMed]

Cernat, R.

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

Chandrasekhar, S..

S. Chandrasekhar, and N. V. Madhusudana, "Orientational Order in p-Azoxyanisole, p-Azoxyphenetole and their mixtures in the nematic phase," J. Phys. Colloq. 30(C4), C4-24 (1969).
[CrossRef]

Chen, C. Y.

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Chirtoc, I.

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

Chirtoc, M.

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

Davis, M.

M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973).
[CrossRef]

de Jeu, W.

A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982).
[CrossRef]

Duguay, B.

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

Escoubes, M.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Evans, M.

M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973).
[CrossRef]

Ezdi, K.

Fujikake, H.

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

Gauza, S.

J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004).
[CrossRef]

Gestblom, B.

S. Urban, A. Würflinger, and B. Gestblom, "On the derivation of the nematic order parameter from the dielectric relaxation times," Phys. Chem. Chem. Phys. 1(11), 2787-2791 (1999).
[CrossRef]

Ghattan, Z.

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

Glorieux, C.

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

Gray, G. W.

G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973).
[CrossRef]

Haller, I.

I. Haller, "Thermodynamic and static properties of liquid crystals," Solid-State Chemistry 10, 103-118 (1975).
[CrossRef]

Harrison, K. J.

G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973).
[CrossRef]

Hasek, T.

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

Helfrich, W.

M. Schadt and W. Helfrich, "Voltage-Dependent Optical Activity of a Twisted Nematic Liquid Crystal," Appl. Phys. Lett. 18(4), 127-128 (1971).
[CrossRef]

Horn, R. G.

R. G. Horn, "Refractive indices and order parameters of two liquid crystals," J. Phys. 39, 105-109 (1978).
[CrossRef]

Hsieh, C. F.

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Hübers, H. W.

Jacobsen, R. H.

Jansen, C.

M. Scheller, C. Jansen, and M. Koch, "Analyzing sub-100-μm samples with transmission terahertz time domain spectroscopy," Opt. Commun. 282(7), 1304-1306 (2009).
[CrossRef]

Jepsen, P. U.

Kamoda, H.

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

Keiding, S. R.

Knobloch, P.

D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001).
[CrossRef]

Koch, M.

R. Wilk, N. Vieweg, O. Kopschinski, and M. Koch, "Liquid crystal based electrically switchable Bragg structure for THz waves," Opt. Express 17(9), 7377-7382 (2009).
[CrossRef] [PubMed]

M. Scheller, C. Jansen, and M. Koch, "Analyzing sub-100-μm samples with transmission terahertz time domain spectroscopy," Opt. Commun. 282(7), 1304-1306 (2009).
[CrossRef]

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, "Impact of the contact metallization on the performance of photoconductive THz antennas," Opt. Express 16(24), 19695-19705 (2008).
[CrossRef] [PubMed]

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001).
[CrossRef]

Kopschinski, O.

R. Wilk, N. Vieweg, O. Kopschinski, and M. Koch, "Liquid crystal based electrically switchable Bragg structure for THz waves," Opt. Express 17(9), 7377-7382 (2009).
[CrossRef] [PubMed]

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

Kuki, T.

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

Lackner, A. M.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Lalanne, J. R.

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

Larkin, I.

M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973).
[CrossRef]

Lehmann, O.

O. Lehmann, "Über fliessende Krystalle," Z. Phys. Chem. 4, 462-472 (1889).

Li, J.

J. Li, and S. T. Wu, "Extended Cauchy equations for the refractive indices of liquid crystals," J. Appl. Phys. 95(3), 896-901 (2004).
[CrossRef]

J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004).
[CrossRef]

Lim, K. C.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Lin, Y. F.

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Luessem, G.

D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001).
[CrossRef]

Madhusudana, N. V...

S. Chandrasekhar, and N. V. Madhusudana, "Orientational Order in p-Azoxyanisole, p-Azoxyphenetole and their mixtures in the nematic phase," J. Phys. Colloq. 30(C4), C4-24 (1969).
[CrossRef]

Maier, W.

W. Maier, and A. Saupe, Z. Naturforsch. B 14a, 882 (1959).

Marcelja, S.

S. Marčelja, "Chain ordering in liquid crystals. I. Even-odd effect," J. Chem. Phys. 60(9), 3599-3604 (1974).
[CrossRef]

Margerum, J. D.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

McEwen, R. S.

R. S. McEwen, "Instrument Science and Technology," J. Phys. E Sci. Instrum. 20(4), 364-377 (1987).
[CrossRef]

Mikulics, M.

Miller, L. J.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Mizuno, K.

Murthy, V. R.

Y. N. Murthy and V. R. Murthy, "Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals," Cryst. Res. Technol. 32(7), 999-1005 (1997).
[CrossRef]

Murthy, Y. N.

Y. N. Murthy and V. R. Murthy, "Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals," Cryst. Res. Technol. 32(7), 999-1005 (1997).
[CrossRef]

Nash, J. A.

G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973).
[CrossRef]

Nomoto, T.

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

Nose, T.

Nozokido, T.

Pan, C. L.

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Pan, R. P.

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Pineri, M.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Prasad, J. S.

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

Prasad, S.

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

Proutiere, A.

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

Pupeza, I.

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

Ratto, J. A.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Rayez, J. C.

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

Raynes, E. P.

E. P. Raynes and I. A. Shanks, "Fast-Switching Twisted Nematic Electro-Optical Shutter and Colour Filter," Electron. Lett. 10(7), 114-115 (1974).
[CrossRef]

Reinitzer, F.

F. Reinitzer, "Beiträge zur Kenntniss des Cholesterins," Monatsh. Chem. 9(1), 421-441 (1888).
[CrossRef]

Ristori, S.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Sambles, J. R.

F. Yang and J. R. Sambles, "Microwave liquid-crystal variable phase grating," Appl. Phys. Lett. 85(11), 2041-2043 (2004).
[CrossRef]

Sato, F.

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

Sato, S.

Saupe, A.

W. Maier, and A. Saupe, Z. Naturforsch. B 14a, 882 (1959).

Schadt, M.

M. Schadt and W. Helfrich, "Voltage-Dependent Optical Activity of a Twisted Nematic Liquid Crystal," Appl. Phys. Lett. 18(4), 127-128 (1971).
[CrossRef]

Scheller, M.

Shahabadi, M.

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

Shanks, I. A.

E. P. Raynes and I. A. Shanks, "Fast-Switching Twisted Nematic Electro-Optical Shutter and Colour Filter," Electron. Lett. 10(7), 114-115 (1974).
[CrossRef]

Sherman, E.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Shivaprakash, N. C.

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

Smith, W. H.

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Thoen, J.

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

Thomas, M.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Turchinovich, D.

D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001).
[CrossRef]

Urban, S.

S. Urban, A. Würflinger, and B. Gestblom, "On the derivation of the nematic order parameter from the dielectric relaxation times," Phys. Chem. Chem. Phys. 1(11), 2787-2791 (1999).
[CrossRef]

Viani, R.

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

Vieweg, N.

Volino, F.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Vuks, M. F.

M. F. Vuks, "Determination of the Optical Anisotropy of Aromatic Molecules from the Double Refraction of Crystals," Opt. Spektrosk. 20, 644-651 (1966).

Wilk, R.

R. Wilk, N. Vieweg, O. Kopschinski, and M. Koch, "Liquid crystal based electrically switchable Bragg structure for THz waves," Opt. Express 17(9), 7377-7382 (2009).
[CrossRef] [PubMed]

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, "Impact of the contact metallization on the performance of photoconductive THz antennas," Opt. Express 16(24), 19695-19705 (2008).
[CrossRef] [PubMed]

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

Wu, S. T.

J. Li, and S. T. Wu, "Extended Cauchy equations for the refractive indices of liquid crystals," J. Appl. Phys. 95(3), 896-901 (2004).
[CrossRef]

J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004).
[CrossRef]

S. T. Wu, "Absorption measurements of liquid crystals in the ultraviolet, visible, and infrared," J. Appl. Phys. 84(8), 4462-4465 (1998).
[CrossRef]

S. T. Wu, "Birefringence dispersions of liquid crystals," Phys. Rev. A 33(2), 1270-1274 (1986).
[CrossRef] [PubMed]

Würflinger, A.

S. Urban, A. Würflinger, and B. Gestblom, "On the derivation of the nematic order parameter from the dielectric relaxation times," Phys. Chem. Chem. Phys. 1(11), 2787-2791 (1999).
[CrossRef]

Yang, F.

F. Yang and J. R. Sambles, "Microwave liquid-crystal variable phase grating," Appl. Phys. Lett. 85(11), 2041-2043 (2004).
[CrossRef]

Appl. Opt.

Appl. Phys. Lett.

M. Schadt and W. Helfrich, "Voltage-Dependent Optical Activity of a Twisted Nematic Liquid Crystal," Appl. Phys. Lett. 18(4), 127-128 (1971).
[CrossRef]

H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003).
[CrossRef]

F. Yang and J. R. Sambles, "Microwave liquid-crystal variable phase grating," Appl. Phys. Lett. 85(11), 2041-2043 (2004).
[CrossRef]

C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006).
[CrossRef]

Chem. Mater.

J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993).
[CrossRef]

Cryst. Res. Technol.

Y. N. Murthy and V. R. Murthy, "Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals," Cryst. Res. Technol. 32(7), 999-1005 (1997).
[CrossRef]

Electron. Lett.

G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973).
[CrossRef]

E. P. Raynes and I. A. Shanks, "Fast-Switching Twisted Nematic Electro-Optical Shutter and Colour Filter," Electron. Lett. 10(7), 114-115 (1974).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron.

R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008).
[CrossRef]

J Infrared Milli Terahz Waves

R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009).
[CrossRef]

J. Appl. Phys.

R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008).
[CrossRef]

S. T. Wu, "Absorption measurements of liquid crystals in the ultraviolet, visible, and infrared," J. Appl. Phys. 84(8), 4462-4465 (1998).
[CrossRef]

J. Li, and S. T. Wu, "Extended Cauchy equations for the refractive indices of liquid crystals," J. Appl. Phys. 95(3), 896-901 (2004).
[CrossRef]

J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004).
[CrossRef]

J. C. S. Faraday II

M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973).
[CrossRef]

J. Chem. Phys.

S. Marčelja, "Chain ordering in liquid crystals. I. Even-odd effect," J. Chem. Phys. 60(9), 3599-3604 (1974).
[CrossRef]

J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984).
[CrossRef]

J. Opt. Soc. Am. B

J. Phys.

R. G. Horn, "Refractive indices and order parameters of two liquid crystals," J. Phys. 39, 105-109 (1978).
[CrossRef]

A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982).
[CrossRef]

J. Phys. Colloq.

S. Chandrasekhar, and N. V. Madhusudana, "Orientational Order in p-Azoxyanisole, p-Azoxyphenetole and their mixtures in the nematic phase," J. Phys. Colloq. 30(C4), C4-24 (1969).
[CrossRef]

J. Phys. E Sci. Instrum.

R. S. McEwen, "Instrument Science and Technology," J. Phys. E Sci. Instrum. 20(4), 364-377 (1987).
[CrossRef]

Liq. Cryst.

I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004).
[CrossRef]

K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993).
[CrossRef]

Mol. Cryst. Liq. Cryst

N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982).
[CrossRef]

Monatsh. Chem.

F. Reinitzer, "Beiträge zur Kenntniss des Cholesterins," Monatsh. Chem. 9(1), 421-441 (1888).
[CrossRef]

Opt. Commun.

M. Scheller, C. Jansen, and M. Koch, "Analyzing sub-100-μm samples with transmission terahertz time domain spectroscopy," Opt. Commun. 282(7), 1304-1306 (2009).
[CrossRef]

Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008).
[CrossRef]

Opt. Express

Opt. Spektrosk.

M. F. Vuks, "Determination of the Optical Anisotropy of Aromatic Molecules from the Double Refraction of Crystals," Opt. Spektrosk. 20, 644-651 (1966).

Phys. Chem. Chem. Phys.

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Figures (8)

Fig. 1.
Fig. 1.

Molecular structure of 6CB according to Ref [22]. For simplicity, the hydrogen atoms are neglected and the phenyl rings are illustrated in a planar conformation.

Fig. 2.
Fig. 2.

Wavelength dependent THz refractive index (a) and absorption coefficient (b) of 5CB at 25.7° C together with measurements from the visible and the IR (cf. Ref [31]. and [32]).

Fig. 3.
Fig. 3.

(a) Refractive index and (b) absorption coefficient at 1.5 THz versus the reduced temperature for 5CB, 6CB, and 7CB.

Fig. 4.
Fig. 4.

Principle polarizability of 5CB, 6CB and 7CB at 1.5 THz calculated according to the Vuks’s approximation.

Fig. 5.
Fig. 5.

Principle polarizability of 5CB, 6CB, and 7CB versus the number of C atoms in the alkyl chain. Data are taken from Fig. 4 at a reduced temperature of T-TNI = 10 K.

Fig. 6.
Fig. 6.

Haller plot of S · Δγ/α̅ on the normalized reduced temperature τ.

Fig. 7.
Fig. 7.

Order parameter S of 5CB, 6CB, and 7CB over the normalized reduced temperature τ obtained using Haller’s extension to Vuks’ approximation.

Fig. 8.
Fig. 8.

Frequency dependent main polarizabilities for 5CB, 6CB, and 7CB.

Tables (1)

Tables Icon

Table 1. Temperatures for the crystal/nematic (TCN) and the nematic/isotropic phase transition (TNI) as well as the reduced temperature TCN - TNI. Ref [21].

Equations (6)

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( α e α o ) = S ( γ γ )
γ = α ̅ + 2 3 S ( α e α o )
γ = α ̅ 2 3 S ( α e α o )
n e / o 2 1 n e / o 2 + 2 = 4 π 3 N α e / o
n e / o 2 1 n ̅ 2 + 2 = 4 π 3 N α e / o ,
S = n e 2 n o 2 n ̅ 2 1 α ̅ Δ γ ,

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