THz time-domain spectroscopy on 4-(trans-4'-pentylcyclohexyl)-benzonitril

Turchinovich, Dmitry; Knobloch, P.; Luessem, Georg; Koch, Martin

doi:10.1117/12.449955

Cited by 26 publications

(15 citation statements)

References 2 publications

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“…Early measurements of the terahertz properties of LCs were on pure materials such as 4-(trans-4 0 -pentylcyclohexyl)-benzonitrile (PCH-5), 134 and 4-cyano-4 0 -n-pentylbiphenyl (5-CB), 4-cyano-4 0 -n-hexylbiphenyl (6-CB), 4-cyano-4 0 -n-heptylbiphenyl (7-CB), and 4-cyano-4-n-octylbiphenyl (8-CB). [135][136][137][138] While the terahertz birefringence for PCH-5 was found to be much smaller than at optical frequencies, the cyano-biphenyl (CB) family of LCs were generally observed to display birefringences at terahertz frequencies that were similar to (or slightly smaller than) optical frequencies, and as the temperature approaches the clearing temperature (i.e., the LC-isotropic transition), the ordinary and extraordinary refractive indices were observed to converge to a single value, normally closer to the ordinary refractive index than the extraordinary.…”

Section: -108mentioning

confidence: 99%

Terahertz Time-Domain and Low-Frequency Raman Spectroscopy of Organic Materials

2015

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With the ongoing proliferation of terahertz time-domain instrumentation from semiconductor physics into applied spectroscopy over the past decade, measurements at terahertz frequencies (1 THz [ 10 12 Hz [ 33 cm À1) have attracted a sustained growing interest, in particular the investigation of hydrogen-bonding interactions in organic materials. More recently, the availability of Raman spectrometers that are readily able to measure in the equivalent spectral region very close to the elastic scattering background has also grown significantly. This development has led to renewed efforts in performing spectroscopy at the interface between dielectric relaxation phenomena and vibrational spectroscopy. In this review, we briefly outline the underlying technology, the physical phenomena governing the light-matter interaction at terahertz frequencies, recent examples of spectroscopic studies, and the current state of the art in assigning spectral features to vibrational modes based on computational techniques.

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Section: -108mentioning

confidence: 99%

Terahertz Time-Domain and Low-Frequency Raman Spectroscopy of Organic Materials

2015

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“…With THz TDS, both the THz refractive index n and the absorption coefficient α can be precisely determined from the measured data over a broad frequency range. The first LC THz TDS measurements were made by Turchinovich et al on PCH5 [19]. This report was followed by several papers published by Prof. Pan's group on 5CB, 6CB, 7CB, 8CB [20][21][22][23][24][25], PCH5 [20,22], E7 [26,27], and a ferroelectric liquid crystal [28].…”

Section: State Of the Artmentioning

confidence: 94%

Liquid Crystals and their Applications in the THz Frequency Range

Vieweg

Jansen

Koch

2012

Terahertz Spectroscopy and Imaging

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We present a survey through the study of liquid crystals with terahertz time domain spectroscopy. The macroscopic dielectric properties such as the refractive index and the absorption coefficient for both ordinary and extraordinary polarization of various liquid crystals are presented and the underlying physical mechanisms are discussed. Furthermore, we deduce the microscopic characteristics such as the order parameter and the polarizabilities from the measured data.

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“…The birefringence of 4-(trans-4'-pentylcyclohexyl)-benzonitrile (PCH5) in the 0.1 to 0.8 THz range (~0.01), on the other hand, were found to be much smaller than those in the visible range (~0.12). 9 We have measured the optical constants of 5CB, E7 (both from Merck) and PCH5 (Aldrich) using the method of THz time-domain spectroscopy. The test cell was constructed as a double-cell with a liquid crystal cell and an empty reference cell side by side.…”

Section: Thz Birefringence and Optical Constants Of Liquid Crystalsmentioning

confidence: 99%

Recent progress in liquid crystal THz optics

Pan

2006

SPIE Proceedings

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Recently, there have been increasing interests in the study of liquid-crystal-based devices for application in the submillimeter wave or THz frequency range. In this paper, we present recent progress in liquid crystal THz optics from our group. Using time-domain THz spectroscopy, we have determined the complex indices of refraction of nematic liquid crystals, 5CB, PCH5 and E7 from 0.2 to beyond 1 THz. Significantly, the birefringence of 5CB and E7 are found to be as large as 0.2 at THz frequencies, while the absorption is negligible. Electrical-field and magnetic-field-controlled birefringence in LC were also investigated. A tunable room-temperature THz phase shifter using magnetic-fieldcontrolled birefringence in nematic 5CB gives a phase shift as large as 108° at 1.0 THz. Phase shift exceeding 360° at 1 THz, an important milestone, was realized by using a sandwiched LC (E7, Merck) cell as thick as 3 mm. The magnetically tuned LC phase shifter served as key components in a two-element tunable LC Lyot filter. The tuning range of the filter is from 0.388 to 0.564 THz or a fractional tuning range of ~ 40%. Our work clearly demonstrates the potential of liquid crystal devices for THz applications. Finally, we will present initial works on control of enhanced THz transmission through a metallic hole array with nematic liquid crystals. Our work clearly demonstrates the potential of liquid crystal devices for THz applications.

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THz time-domain spectroscopy on 4-(trans-4'-pentylcyclohexyl)-benzonitril

Cited by 26 publications

References 2 publications

Terahertz Time-Domain and Low-Frequency Raman Spectroscopy of Organic Materials

Terahertz Time-Domain and Low-Frequency Raman Spectroscopy of Organic Materials

Liquid Crystals and their Applications in the THz Frequency Range

Recent progress in liquid crystal THz optics

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