Simple method for the determination of refractive indices and loss parameters for liquid-crystal materials in the millimeter-wave region.

A reflection-type liquid crystal (LC) test cell is prepared with a rectangular waveguide for investigation of a novel method to determine refractive indices and loss parameters of nematic liquid-crystal materials. As the bottom of the test cell is sealed with a glass window and the top of the cell is capped with a metal-tipped movable reflector after the LC materials are injected, both ends of the waveguide test cell have large reflectance. Thus the reflection properties of the LC test cell can be well described by a multiple-beam interference model. A simple method for the determination of refractive indices from the reflection measurement data is proposed based on results of some investigations with the theoretical model. Commercially available LC materials have been measured with this method at a millimeter-wave frequency (50 GHz) by use of a simple experimental setup with a Gunn oscillator and a diode detector.

[1]  Shin-Tson Wu,et al.  Infrared birefringence of liquid crystals , 1984 .

[2]  H. Mada,et al.  Dielectric Properties of n-Pentyl-p-n-Cyanobiphenyl in Wide Frequency Range , 1993 .

[3]  Daniel Dolfi,et al.  Modeling, Synthesis and Characterization of a Millimeter-Wave Multilayer Microstrip Liquid Crystal Phase Shifter , 1997 .

[4]  Elena Sherman,et al.  Liquid crystal birefringence for millimeter wave radar , 1993 .

[5]  C. Grover,et al.  Dispersion curve measurement using Talbot bands , 1988 .

[6]  E. Sherman,et al.  A Liquid Crystal Based Polymer for Applications in MMW Modulation Devices , 1997 .

[7]  Susumu Sato,et al.  Electrically Controlled Millimeter-Wave Transmission Properties of Stack-Layered Liquid Crystal Cells with Metal Substrates. , 2001 .

[8]  Anna M. Lackner,et al.  Liquid crystal millimeter wave electronic phase shifter , 1993 .

[9]  I. Abdulhalim.  Dispersion Relations for the Refractive Indices and the Effective Birefringence of Liquid Crystals , 1991 .

[10]  Shin-Tson Wu,et al.  Potential liquid crystal mixtures for Co2 laser application , 1994 .

[11]  Wu,et al.  Birefringence dispersions of liquid crystals. , 1986, Physical review. A, General physics.

[12]  Hideo Fujikake,et al.  Microwave variable delay line using dual-frequency switching-mode liquid crystal , 2002 .

[13]  K Hirabayashi,et al.  Free-space optical interconnections with liquid-crystal microprism arrays. , 1995, Applied optics.

[14]  Daniel Dolfi,et al.  Liquid crystal microwave phase shifter , 1993 .

[15]  Hitoshi Mada,et al.  Wavelength and Voltage Dependences of Refractive Indices of Nematic Liquid Crystals , 1976 .

[16]  Refractive index dispersions of liquid crystals , 1993 .

[17]  E. Sherman,et al.  Microtubule particle dispersion in liquid crystal hosts , 1993 .

[18]  Toshiaki Nose,et al.  Millimeter-Wave Transmission Properties of Nematic Liquid-Crystal Cells with a Grating-Patterned Electrode Structure , 2000 .

[19]  Jayantilal Shamjibhai Patel,et al.  Electrically tunable and polarization insensitive Fabry–Perot étalon with a liquid‐crystal film , 1991 .

[20]  T. Nozokido,et al.  Refractive index of nematic liquid crystals in the submillimeter wave region. , 1997, Applied optics.

[21]  K. Ono,et al.  Effect of the Thickness of Alignment Layer on the Low-Frequency Dielectric Dispersion of a Nematic Liquid Crystal , 1996 .

[22]  M. Honma,et al.  Determination of the Insertion Loss and Refractive Index Anisotropy in Nematic Liquid Crystal Materials Using a V-band Waveguide Transmission Cell , 2004 .

[23]  Electrically Controlled Millimeter-Wave Focusing Properties of Liquid Crystal Lens , 2002 .