Liquid crystal electro-optical and nonlinear optical switches
Electro-optical and nonlinear optical switching devices using liquid crystal film are presented. In electro-optical switching studies, the theory of liquid crystal axis deformation and the electrohydrodynamics in response to an electric field have been studied. The realignment process depends on the relationships between the direction of the electric field and the dielectric constant. A reverse mode modulation technique using this realignment phenomenon was proposed and experimentally demonstrated. The enhancement of the response and time and contrast ratio of the reverse mode was achieved by using optical spatial filter. In nonlinear optical switching, theoretical and experimental investigations were conducted using isotropic liquid crystals. Theoretical models take into account the laser beam parameters (intensity, wavelength, time scale, etc.) and the material parameters (absorption, refractive index, nonlinearity, temperature, etc.). Two types of laser inputs temporal waveforms, i.e., square and gaussian, have been considered. Both pure and dye-doped liquid crystals were investigated. The induced local temperature change and nonlinear phase shift have been quantitatively analyzed and detailed comparison between theory and experiments are made. These results indicate that the limiting threshold for an isotropic liquid crystal cell is on the order of 10[sup [minus]1] [approximately] 10[sup [minus]3]mJ/cm[sup 2] corresponding to 10[sup 0] [approximately] 10[sup 2]MW/cm[sup 2] and demonstrate that practical and broad bandwidth optical sensor protection devices can be designed and fabricated.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (United States)
- OSTI ID:
- 7302837
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
LIQUID CRYSTALS
ELECTRO-OPTICAL EFFECTS
NONLINEAR OPTICS
SWITCHES
ELECTROHYDRODYNAMICS
ELECTRICAL PROPERTIES
LASER RADIATION
OPTICAL PROPERTIES
CRYSTALS
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
EQUIPMENT
FLUID MECHANICS
FLUIDS
HYDRODYNAMICS
LIQUIDS
MECHANICS
OPTICS
PHYSICAL PROPERTIES
RADIATIONS
360606* - Other Materials- Physical Properties- (1992-)
426000 - Engineering- Components
Electron Devices & Circuits- (1990-)