Optical Switch Evaluation Support.

摘要

Extensive testing has been done on nonlinear interface optical switch (NIOS) devices fabricated from laser deposited nonstoichiometric tungsten oxide films. A Fresnel coefficient formalism for evaluating the indices of refraction of the films has been developed. Three cycles of testing involving changing the tungsten-oxygen stoichiometry have not produced extremely large photorefractive effects. It was decided, after using a mathematical model to determine the required incident and reflection angles, to make the next set of NIOS devices from a film deposited on ZnS prisms. ZnS more closely matches the low light intensity index of the films. Preliminary studies of further changes to produce stronger nonlinearity have been performed. Raman spectroscopy showed that these films heated in oxygen organize themselves into octohedra, which are thought to be necessary for the photorefractive effects observed in titanates and niobates. Heating the films in vacuum produces blue films which ESCA shows contain tungsten in the +4 oxidation state. Such electron rich species might be able to provide highly polarizable charge carriers. In addition to use as optical switches, use of these films to make reconfigurable Dammann gratings has been studied. These gratings would allow optical addressing of large size S-SEED arrays. Dammann gratings, SEED Devices, NOIS, Optical switches, Nonlinear optics, Nonlinear interface, LCVD, Laser chemical vapor deposition, Tungsten oxides, Tungsten bronzes, Refractive index measurement, Photorefractive materials.