Optical steering of mutual capacitance in nematic liquid crystal cell

Abstract: In this study a variable capacitor made of Nematic Liquid Crystal cell is proposed and analyzed theoretically. The mutual capacitance is steered with an optical beam of a Gaussian shape launched into the cell. The optical field changes the orientation of the molecules and affects the capacitance. By using Frank-Oseen elastic theory the molecular reorientation is simulated. The influence of various parameters on capacitance such beam width, anchoring condition, externally applied voltage, beam power and launching position is presented. For instance, the maximum tuning range is achieved for wide beams and the molecules initially aligned close to the propagation axis. It is also proved that launching position, especially for narrow beams, has limited influence on capacitance. The proposed component can be used, for instance, in optical power meters, as a feedback in laser or diode systems or just as a variable capacitor in optoelectronic circuits. One of the advantages of this device is that the beam passes through the element, so steering of the capacitance or measuring the parameters of the beam can be realized without splitting the beam. Moreover, due to the low thickness of the liquid crystal layer the attenuation is very low.