Electro-optic properties for liquid crystal phase gratings

A new type of liquid crystal device was developed by applying a concept of liquid crystal phase gratings (LCPGs). LCPGs are composed of square-wave phase gratings constructed with poly(methyl methacrylate) and liquid crystals which fill the grating grooves. The typical sizes of the phase grating are 10 micrometers in width and 2 micrometers in depth. The transmitted light wavelength can be easily controlled by changing applied voltage. The transmittance varied from less than 1 for monochromatic polarized light, when applied voltage varied from 0 V to 5 V. Rise times for the light varied from 0.2 ms to 7 ms with applied voltage, and were inversely proportional to the square of the applied voltage. Decay times, which depend slightly on the applied voltage, were about 4 ms. A transmitted light, i.e., an observed color (e.g., R,G,B and white), was dependent on not only applied voltage but also grating depth. When two of the LCPGs were combined in such a way that their grating lines were oriented perpendicular to each other, these LCPGs were applicable to nonpolarized light.