Measurement of liquid crystal materials in the millimeter-wave region using a network analyzer

摘要

Since the liquid Crystal (LC) materials have a very large electrooptic effect, an application for flat panel display is extremely proceeded in these days. However; their high potential applications can also be expected in other electromagnetic wavelength region. Only the optical properties in the visible region are usually discussed by the large demand from the display application. In this work, we are trying to measure the refractive index of some commercially available nematic liquid crystal materials in the millimeter-Wave Region. Here, rectangular waveguide is used for the test LC cell, and the transmission properties are measured under magnetic field application. It is confirmed that the usual nematic materials are considerably transparent at millimeter wavelengths and the refractive index anisotropy decreases to less than a half but still large.