Abstract:
La présente invention concerne un dispositif de contrôle de fréquence optique (F1,F2) autour d'une fréquence centrale de travail (F0). Ce dispositif comprend une cavité verticale (2) formée de deux parois (3a,3b) parallèles et partiellement réfléchissantes, et une membrane (6) comportant au moins une couche (7a,7b) structurée sous la forme d'un cristal photonique. Dans ce dispositif, les deux parois (3a,3b) sont séparées d'une distance optique sensiblement proportionnelle à la moitié de la longueur d'onde (⋋0) correspondant à la fréquence centrale de travail (F0). La membrane (6) est intégrée entre les parois (3a,3b) de la cavité (2) et agencée pour présenter un mode de résonance optique à cette longueur d'onde centrale de travail (⋋0). Au moins une couche du dispositif est constituée en au moins une portion d'un matériau présentant des propriétés optiques non-linéaires. La présente invention concerne également différents systèmes mettant en œuvre des moyens de pompage optique et un tel dispositif de contrôle de fréquence optique, ainsi qu'un procédé de fabrication d'un tel dispositifde contrôle de fréquence optique.
Abstract:
The reflectivity and transmissivity of building and vehicle surfaces is maintained while employing partial, variable, selective, or asymmetric diffusers(302) between a surface(304) and an external light source (306) such that the reflected light is diffused to produce a reduction in glare, while minimally effecting the specular or collimated transmission (if any) of light through the surface(304). Glare is also reduced by utilizing diffuser devices(302) that reflect light in a temperature dependent manner.
Abstract:
A reflecting device having electrically controllable variable reflection is provided having a periodic array of liquid crystals disposed in a polymer matrix (76), the liquid crystal having an index of refraction variable in response to an applied electric field, and means (74, 80) for applying an electric field across the device to provide first and second applied electric field strengths. The index of refraction of the liquid crystal and the index of refraction of the polymer matrix, n?p?, are mismatched at the first and second applied electric field strengths to provide differing peak reflective wavelengths (500, 512).
Abstract:
Devices that comprise novel, mesoscopically periodic materials that combine crystalline colloidal array (CCA) self assembly with the temperature induced volume phase transistions of various, materials, preferably poly (N-isopropylacrylamide) (PNIPAM) are disclosed. In one embodiment, a PNIPAMCCA is formed in an aqueous media (14) and contained within cell means (16). In another embodiment, a CCA of charged particles (12) is formed and polymerized in a PNIPAM hydrogel. Methods for making these devices are also disclosed. The devices of the present invention are useful in many applications including, for example, optical switches, optical limiters, optical filters, display devices and processing elements. The devices are further useful as membrane filters. All of these devices have the feature of being tunable in response to temperature. Devices that change diffracted wavelength in response to pressure are also disclosed.
Abstract:
A display device is provided that includes a photovoltaic cell, a dichroic reflector adjacent to the photovoltaic cell, and a low refractive index layer adjacent to the dichroic reflector. The low refractive index layer can have an index of refraction of from about 1.1 to about 1.4.
Abstract:
The present invention is directed to a structure, having first areas consisting of or comprising a network of organic polymer material and second areas consisting of a nematic and/or smectic liquid crystal material, comprising at least one or more nematic and/or smectic liquid crystals and a photoluminescent material, wherein the first and second areas alternate in at least a first plane, while the composition of the film is substantially invariable in at least one direction which is angular to the said first plane, or second areas are completely surrounded by first areas, and the said areas are located in a periodic pattern, wherein the nematic and/or smectic liquid crystal material in the second areas extends in the longitudinal direction of the said areas from one end of the area to the other, the structure being arranged between two substrates, at least one of which is light transmitting. The structure together with the substrates may be a Bragg grating and can be used as a DFB laser. It can be prepared by providing a homogeneous and isotropic mixture including a photocurable monomer/oligomer, a nematic and/or smectic liquid crystal, and a photoluminescent material, filling said mixture into the space between two substrates and irradiating same with a light field such that areas of the mixture are irradiated while others are not. Under the irradiation, the mixture separates into areas comprising photocured polymer and areas consisting or comprising liquid crystals and photoluminescent material.