Abstract: A transparent device for use in optical applications, and methods for using and manufacturing the device are disclosed. The device generally requires several layers, including (i) a first layer comprising a transparent conductive oxide (such as indium tin oxide (ITO)), (ii) a second layer comprising a transparent semiconductor (e.g., a pn-heterojunction or a pn-homojunction), the second layer having a surface facing the first layer, (iii) a third layer comprising a liquid crystal (such as E7), the third layer having a surface facing the second layer, and (iv) a fourth layer comprising either a second transparent conductive oxide or a second transparent semiconductor, the fourth layer having a surface facing the third layer. When light illuminates a surface of the transparent metal oxide pn-heterojunction or transparent metal oxide pn-homojunction, it induces photoconductivity, modifying the surface charges.

Abstract: A transparent device for use in optical applications, and methods for using and manufacturing the device are disclosed. The device generally requires several layers, including (i) a first layer comprising a transparent conductive oxide (such as indium tin oxide (ITO)), (ii) a second layer comprising a transparent semiconductor (e.g., a pn-heterojunction or a pn-homojunction), the second layer having a surface facing the first layer, (iii) a third layer comprising a liquid crystal (such as E7), the third layer having a surface facing the second layer, and (iv) a fourth layer comprising either a second transparent conductive oxide or a second transparent semiconductor, the fourth layer having a surface facing the third layer. When light illuminates a surface of the transparent metal oxide pn-heterojunction or transparent metal oxide pn-homojunction, it induces photoconductivity, modifying the surface charges.

Abstract: A transparent device for use in optical applications, and methods for using and manufacturing the device are disclosed. The device generally requires several layers, including (i) a first layer comprising a transparent conductive oxide (such as indium tin oxide (ITO)), (ii) a second layer comprising a transparent semiconductor (e.g., a pn-heterojunction or a pn-homojunction), the second layer having a surface facing the first layer, (iii) a third layer comprising a liquid crystal (such as E7), the third layer having a surface facing the second layer, and (iv) a fourth layer comprising either a second transparent conductive oxide or a second transparent semiconductor, the fourth layer having a surface facing the third layer. When light illuminates a surface of the transparent metal oxide pn-heterojunction or transparent metal oxide pn-homojunction, it induces photoconductivity, modifying the surface charges.

Abstract: A transparent device for use in optical applications, and methods for using and manufacturing the device are disclosed. The device generally requires several layers, including (i) a first layer comprising a transparent conductive oxide (such as indium tin oxide (ITO)), (ii) a second layer comprising a transparent semiconductor (e.g., a pn-heterojunction or a pn-homojunction), the second layer having a surface facing the first layer, (iii) a third layer comprising a liquid crystal (such as E7), the third layer having a surface facing the second layer, and (iv) a fourth layer comprising either a second transparent conductive oxide or a second transparent semiconductor, the fourth layer having a surface facing the third layer. When light illuminates a surface of the transparent metal oxide pn-heterojunction or transparent metal oxide pn-homojunction, it induces photoconductivity, modifying the surface charges.

Abstract: A spectrally-selective reflective optical film comprises at least two anisotropic layers, each of the layers having a phase retardation value and an optical axis orientation pattern within the layer; the optical axis orientation patterns exhibiting a discontinuity at the boundary of the at least two layers; and at least one substrate holding the film. At least a part of the anisotropic layers may be chiral. The materials comprising the anisotropic layers may be selected from liquid crystal polymers, azobenzene liquid crystal polymers, liquid crystals, azobenzene liquid crystals, polymer films with stressed birefringence, and combinations thereof. The materials comprising the anisotropic layers may be doped with at least one dopant from the list comprising nanorods, photorefractive nanoparticles, photovoltaic nanoparticles, lasing dyes, and combinations of thereof. The anisotropic layers may be transparent to infrared wavelengths.

Abstract: A method for synthesizing ferroelectric nanoparticles comprises introducing solutions of Ba(NO3)2 (1 mmol) in 5 ml of deionized water, NaOH (12.5 mmol) in 5 ml of deionized water, Ti(IV) n-butoxide (1 mmol) in 5 ml of 1-butanol, 2.5 ml of oleic acid, and 5 ml of 1-butanol into a Teflon-lined autoclave vessel; heating the vessel to 135° C. for 18 h, resulting in barium titanate nanoparticles; and ball-milling the barium titanate nanoparticles in a solution of oleic acid and heptane to create a colloidal suspension of nanoparticles. The weight ratio of barium titanate:oleic acid:heptane is 1:1:20. The ball-milling step may further comprise introducing a slurry comprising 0.1 g of synthesized BaTiO3 nanocubes, 0.1 g of oleic acid, and 15 mL of heptane into a ball-mill crucible filled with 2 mm ZrO2 balls; subjecting the slurry to rotation at 500 rpm for 5 hours; converting the resulting nanoparticle suspension to a powder using anhydrous ethanol with sequential washing/drying at ambient temperature.

Abstract: An optical/RF apparatus comprising a liquid crystal (LC) layer placed above or below a plasmon layer (e.g., a periodic array of graphene ribbons) to enable the tuning of the surface plasmons by varying the voltage applied to the LC to realize thereby devices such as tunable mid-IR, far-IR or THz modulators and filters.

Abstract: An optical filter or valve comprises autonomously tunable liquid crystal filters in which photoactivated materials such as a photoconductive and photovoltaic substrates or films are used to produce or control application of an electric field to a liquid crystal material to tune the liquid crystal material to the wavelength of the incident light or radiation that is illuminating the filter thereby enabling the filter to automatically and autonomously filter the incident light or radiation.

Abstract: The present invention provides a photorefractive hybrid cell including a window and a gain media disposed adjacent the window. The gain media includes nanoparticles therein. The window includes a material that forms a space-charge field. The gain media includes a material having refractive index properties that depend on an electric field. The nanoparticles include a coating which may include birefringent or polar molecules, other nanoparticles, organic material, or inorganic material.

Abstract: Methods for preparing ferroelectric nanoparticles, liquid crystal compositions containing the ferroelectric nanoparticles, and electronic devices utilizing the ferroelectric nanoparticles are described. The methods of preparing the ferroelectric nanoparticles may include size-reducing a starting material comprising particles of a bulk intrinsically nonferroelectric glass to form glass nanoparticles having an average size of less than 20 nm, the glass nanoparticles comprising ferroelectric nanoparticles. Exemplary bulk intrinsically nonferroelectric glasses may include borosilicate glasses, tellurite glasses, bismuthate glasses, gallate glasses, and mixtures thereof, for example. The size reduction may be accomplished using ball milling with a solvent combination such as n-heptane and oleic acid. Liquid crystal compositions may include the ferroelectric nanoparticles in combination with a liquid crystal.

Abstract: Methods are disclosed for separating and harvesting very small single domain ferroelectric nanoparticles by application of a non-uniform electric or magnetic field gradient. The disclosed methods enable collection of nanoparticles with permanent strong dipole moments for use in a wide variety of applications with greatly improved results.

Abstract: Methods for preparing ferroelectric nanoparticles, liquid crystal compositions containing the ferroelectric nanoparticles, and electronic devices utilizing the ferroelectric nanoparticles are described. The methods of preparing the ferroelectric nanoparticles may include size-reducing a starting material comprising particles of a bulk intrinsically nonferroelectric glass to form glass nanoparticles having an average size of less than 20 nm, the glass nanoparticles comprising ferroelectric nanoparticles. Exemplary bulk intrinsically nonferroelectric glasses may include borosilicate glasses, tellurite glasses, bismuthate glasses, gallate glasses, and mixtures thereof, for example. The size reduction may be accomplished using ball milling with a solvent combination such as n-heptane and oleic acid. Liquid crystal compositions may include the ferroelectric nanoparticles in combination with a liquid crystal.

Abstract: The present invention provides a photorefractive hybrid cell including a window and a gain media disposed adjacent the window. The gain media includes nanoparticles therein. The window includes a material that forms a space-charge field. The gain media includes a material having refractive index properties that depend on an electric field. The nanoparticles include a material which responds orientationally to the presence of an electric or magnetic field.

Abstract: The present invention provides a method for adjusting a diffraction grating to changes in ambient conditions. The method includes writing a diffraction grating in the photorefractive waveguide with a laser, measuring spectral characteristics of the diffraction grating, and allowing the diffraction grating to self-write from interference between a forward beam and a Fresnel reflection, such that the diffraction grating is adjusted for changes in ambient conditions.

Abstract: The present invention provides a photorefractive hybrid cell including a window and a gain media disposed adjacent the window. The gain media includes nanoparticles therein. The window includes a material that forms a space-charge field. The gain media includes a material having refractive index properties that depend on an electric field. The nanoparticles include a material which responds orientationally to the presence of an electric or a magnetic field.

Abstract: The present invention provides a method for automatically activating an optical light valve. The method includes providing a photorefractive cell having a birefringent medium which is doped with nanoparticles and transmitting light through the photorefractive cell to create an electric field in the photorefractive cell such that the alignment state of the birefringent medium and nanoparticles is changed to thereby reduce the intensity of the light being transmitted therethrough, wherein the intensity of light is reduces without an external power source.

Abstract: The present invention provides a photorefractive potassium niobate (KNbO3 ) crystal including a first impurity added substitutionally to the niobium (Nb) site and a second impurity added substitutionally to the potassium (K) site, wherein the first and second impurities are different. There is also provided a method of making the codoped potassium niobate crystal (KNbO3 ) of the present invention wherein the method includes adding at least one of the impurities to a melt composition during crystal growth, adding at least one of the impurities into an existing crystal using thermal diffusion, and/or adding at least one of impurities into an existing crystal using electrically assisted diffusion.