Abstract: Apparatus and methods can include an optical waveguide coupled to a photonic crystal comprising a dielectric material, the photonic crystal located on an exterior surface of the optical waveguide and comprising a first surface including a first array of periodic features on or within the dielectric material, the array extending in at least two dimensions and including an effective dielectric permittivity different from the surrounding dielectric material. In an example, the periodic features include a specified lattice constant, the periodic features configured to extract a portion of propagating optical energy from the waveguide through the photonic crystal, the portion determined at least in part by the specified lattice constant.

Abstract: An electronic device may be provided with light sensors. The electronic device may have an electronic device housing in which a display is mounted. The display may have a transparent layer such as a transparent display cover layer, a thin-film transistor layer, or a color filter layer. An opaque masking layer such as a layer of black ink may be used to cover an inner surface of the transparent layer in an inactive area of the display. Sensor window openings may be formed in the black ink layer. A layer of ink may be formed in each sensor window opening. Each layer of ink may have a diffuse reflectivity that is matched to that of the black ink. A diffuser layer such as a polymer coating layer with light-scattering particles may be coated on the inner surface of the layer of ink in a sensor window opening.

Abstract: An organic electrical device can include a first dielectric substrate including a PVDF-TrFe-CFE terpolymer, a first semiconductor region coupled to a first surface of the first dielectric substrate, and a first gate region coupled to a second surface of the first dielectric substrate, the second surface opposite the first surface and opposite the first semiconductor region. The organic electrical device can include an organic field-effect transistor (OFET), comprising the first gate region, the first dielectric substrate, a first source region, and a first drain region respectively electrically coupled to the first semiconductor region. An electrostrictive actuator or mechanical sensor can be co-integrated on the first dielectric substrate, the actuator or sensor including first and second conductive regions located on opposite surfaces of the first dielectric substrate. The actuator or sensor can be electrically coupled to the OFET, and controlled at least in part by the OFET.

Abstract: Apparatus and methods can include an optical waveguide coupled to a photonic crystal comprising a dielectric material, the photonic crystal located on an exterior surface of the optical waveguide and comprising a first surface including a first array of periodic features on or within the dielectric material, the array extending in at least two dimensions and including an effective dielectric permittivity different from the surrounding dielectric material. In an example, the periodic features include a specified lattice constant, the periodic features configured to extract a portion of propagating optical energy from the waveguide through the photonic crystal, the portion determined at least in part by the specified lattice constant.

Abstract: Apparatus and methods can include an optical waveguide coupled to a photonic crystal comprising a dielectric material, the photonic crystal located on an exterior surface of the optical waveguide and comprising a first surface including a first array of periodic features on or within the dielectric material, the array extending in at least two dimensions and including an effective dielectric permittivity different from the surrounding dielectric material. In an example, the periodic features include a specified lattice constant, the periodic features configured to extract a portion of propagating optical energy from the waveguide through the photonic crystal, the portion determined at least in part by the specified lattice constant.

Abstract: An organic electrical device can include a first dielectric substrate including a PVDF-TrFe-CFE terpolymer, a first semiconductor region coupled to a first surface of the first dielectric substrate, and a first gate region coupled to a second surface of the first dielectric substrate, the second surface opposite the first surface and opposite the first semiconductor region. The organic electrical device can include an organic field-effect transistor (OFET), comprising the first gate region, the first dielectric substrate, a first source region, and a first drain region respectively electrically coupled to the first semiconductor region. An electrostrictive actuator or mechanical sensor can be co-integrated on the first dielectric substrate, the actuator or sensor including first and second conductive regions located on opposite surfaces of the first dielectric substrate. The actuator or sensor can be electrically coupled to the OFET, and controlled at least in part by the OFET.

Abstract: Apparatus and methods can include an optical waveguide coupled to a photonic crystal comprising a dielectric material, the photonic crystal located on an exterior surface of the optical waveguide and comprising a first surface including a first array of periodic features on or within the dielectric material, the array extending in at least two dimensions and including an effective dielectric permittivity different from the surrounding dielectric material. In an example, the periodic features include a specified lattice constant, the periodic features configured to extract a portion of propagating optical energy from the waveguide through the photonic crystal, the portion determined at least in part by the specified lattice constant.

Abstract: Nanocrystalline forms of metal oxides, including binary metal oxide, perovskite type metal oxides, and complex metal oxides, including doped metal oxides, are provided. Methods of preparation of the nanocrystals are also provided. The nanocrystals, including uncapped and uncoated metal oxide nanocrystals, can be dispersed in a liquid to provide dispersions that are stable and do not precipitate over a period of time ranging from hours to months. Methods of preparation of the dispersions, and methods of use of the dispersions in forming films, are likewise provided. The films can include an organic, inorganic, or mixed organic/inorganic matrix. The films can be substantially free of all organic materials. The films can be used as coatings, or can be used as dielectric layers in a variety of electronics applications, for example as a dielectric material for an ultracapacitor, which can include a mesoporous material. Or the films can be used as a high-K dielectric in organic field-effect transistors.