The Research Of Liquid Crystal Photonic Crystal Optical Properties

Photonic crystals are similar with semiconductor band gap of photon forbiddenband, known as the optical semiconductors. In recent years, it has become a hot subject.Photonic crystals will play a revolutionary role in photonics and light electronics. Theliquid crystal can be injected into the photonic crystal as crystal defect layer, this newlycreated devices can show the both characteristics of liquid crystal and the photoniccrystal. This dissertation pays great attention to the optical properties ofone-dimensional liquid photonic crystal which mainly include the following aspects:(1) First of all, this dissertation carries out a theory of bring Nematic liquid crystaldefects into multi-layer one-dimensional liquid crystal to form photonic crystal.According to the transfer matrix, we give out a numerical simulation of its opticalcharacteristics affected by the liquid crystal layer thickness and mediums period number.Through the simulation, we draw a conclusion: The filter peak in the photonicfrequency band gaps moves in the direction of long wave; The filter peak transmissionof the photonics frequency band gaps drops and the half-wave width become narrowwhich provides theoretically basis of making devices.(2) At the second part of the dissertation, we design and make a nematic liquidcrystal photonic crystal device. We analyze its optical characteristics by measuringtransmission spectrum under different voltage, temperature and liquid crystalorientation state. The device also shows up with tuning filter characteristics whenvoltage and temperature changes. Both voltage and temperature rising will contribute toblue shift. Orientation of liquid crystal can affect polarization sensitivity of the device.When liquid crystal molecules parallel to the orientation, the anisotropy of liquid crystallayer is much more obvious than random orientation.(3) At last, we design and make a bravery cholesterc liquid crystal device.Bymeasuring the transmission spectrum under different voltage, temperater and liquidcrystal orientation state, we analyse its optical characteristics. The orientation of liquidcrystal molecules changes as the voltage and temperature does and it shows up with tuning filter characteristics.The spiral arrangement of liquid crystal molecules alwaysexist whether in plane state or focal cone texture state. Refractive index of liquid crystalmolecules can compensate for each other and there is no polarization sensitivity willshow up by the device.