  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.
