Characteristics of the amplitude modulation of light as a result of the Freedericksz transition in a liquid-crystal cell with a dichroic dye

A study was made of the amplitude modulation of light based on the use of the Freedericksz transition in combination with dichroic absorption in cells containing a liquid crystal and a dichroic dye. At low frequencies, the depth of modulation of quasimonochromatic light was about 0.8 within the limits of the width of the absorption spectrum of the dye, but fell to 0.1 at the edges of the spectrum and also when the frequency of switching of the electric field was increased above 1 kHz. The dichroic dye used belongs to the class of ketocyanines which hold promise for the modulation of light by the investigation method.