Abstract: A tunable optical diffraction grating apparatus, such as but not limited to a tunable Fresnel zone lens apparatus, includes a plurality of symmetric repeating structures (i.e., typically concentric rings) located over a substrate and comprising a material susceptible to a transparent to opaque transition for a designated radiation wavelength. The tunable optical diffraction grating apparatus also includes a means for separately effecting the transparent to opaque transition for each of the plurality of symmetric repeating structures to provide a plurality of transparent zones each comprising a variable first sub-plurality of adjacent transparent symmetric repeating structures alternating and interposed between a plurality of opaque zones each comprising a variable second sub-plurality of adjacent opaque symmetric repeating structures. Also included are a method for fabricating the tunable optical diffraction grating apparatus and a method for operating the tunable optical diffraction grating apparatus.

Abstract: Infrared metamaterial arrays containing Au elements immersed in a medium of benzocyclobutene (BCB) were fabricated and selectively etched to produce small square flakes with edge dimensions of approximately 20 ?m. Two unit-cell designs were fabricated: one employed crossed-dipole elements while the other utilized square-loop elements.

Abstract: A resistor, fabricating method, and thermal sensor material for resistors that incorporate high Temperature Coefficient of Resistance (TCR) values and low resistivity for better sensitivity in infrared imaging applications are disclosed. Amorphous oxide thin films, preferably oxides of vanadium (VOx), were deposited on thermally grown silicon dioxide by direct current (DC) magnetron co-sputtering of noble metals (gold and platinum) in a controlled argon/oxygen atmosphere. The ideal conditions for preparing an amorphous vanadium oxide/noble metal thin film are identified. TCR and resistivity results showed that the additions of gold (Au) and platinum (Pt) into VOx reduced the resistivity. However, only gold (Au) was found to improve TCR value. Reducing the amount of oxygen in the thin film, further improved the ratio between TCR and resistivity. Infrared detection and imaging devices can be greatly improved with a “drop-in” amorphous vanadium oxide/noble metal thin film of the present invention.

Abstract: Infrared metamaterial arrays containing Au elements immersed in a medium of benzocyclobutene (BCB) were fabricated and selectively etched to produce small square flakes with edge dimensions of approximately 20 ?m. Two unit-cell designs were fabricated: one employed crossed-dipole elements while the other utilized square-loop elements.

Abstract: A tunable optical diffraction grating apparatus, such as but not limited to a tunable Fresnel zone lens apparatus, includes a plurality of symmetric repeating structures (i.e., typically concentric rings) located over a substrate and comprising a material susceptible to a transparent to opaque transition for a designated radiation wavelength. The tunable optical diffraction grating apparatus also includes a means for separately effecting the transparent to opaque transition for each of the plurality of symmetric repeating structures to provide a plurality of transparent zones each comprising a variable first sub-plurality of adjacent transparent symmetric repeating structures alternating and interposed between a plurality of opaque zones each comprising a variable second sub-plurality of adjacent opaque symmetric repeating structures. Also included are a method for fabricating the tunable optical diffraction grating apparatus and a method for operating the tunable optical diffraction grating apparatus.

Abstract: A resistor, fabricating method, and thermal sensor material for resistors that incorporate high Temperature Coefficient of Resistance (TCR) values and low resistivity for better sensitivity in infrared imaging applications are disclosed. Amorphous oxide thin films, preferably oxides of vanadium (VOx), were deposited on thermally grown silicon dioxide by direct current (DC) magnetron co-sputtering of noble metals (gold and platinum) in a controlled argon/oxygen atmosphere. The ideal conditions for preparing an amorphous vanadium oxide/noble metal thin film are identified. TCR and resistivity results showed that the additions of gold (Au) and platinum (Pt) into VOx reduced the resistivity. However, only gold (Au) was found to improve TCR value. Reducing the amount of oxygen in the thin film, further improved the ratio between TCR and resistivity. Infrared detection and imaging devices can be greatly improved with a “drop-in” amorphous vanadium oxide/noble metal thin film of the present invention.

Abstract: An array of two or more tunable electro-optical reflecting elements where the phase response of one or more elements may be adjusted by a variety of approaches including, but not limited to: a liquid crystal superstrate, schottky contact(s), ultra-violet radiation pulses, and illumination of photoconductive substrates. Methods and apparatus for direct and/or adaptive control of phase response via the above approaches are also discussed.

Abstract: An identification system and associated method for identifying objects includes at least one tag having encoded information attached to the surface of an object to be identified, wherein the tag includes a first FSS-based elliptical polarization filter which provides the encoding. A remotely located receiver including a second FSS-based elliptical polarization filter and a linear polarizer optically coupled to the second filter is operable for differentially attenuating the first and second orthogonal polarization states allowing a determination whether the intensity pattern corresponds to the encoded information.

Abstract: An array of two or more tunable electro-optical reflecting elements where the phase response of one or more elements may be adjusted by a variety of approaches including, but not limited to: a liquid crystal superstrate, schottky contact(s), ultra-violet radiation pulses, and illumination of photoconductive substrates. Methods and apparatus for direct and/or adaptive control of phase response via the above approaches are also discussed.

Abstract: An optical combination includes a substrate, a linear polarizer on the substrate, and a first frequency selective surface (FSS) based elliptical polarization filter on the linear polarizer. The first FSS comprises at least one periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing orientated along a first axis. The pattern is operable to impose a phase differential for one orthogonal linear polarization state relative to the other linear polarization state for electromagnetic radiation having a wavelength between 400 nm and 1 mm, such as 1 ?m to 12 ?m. An identification system and associated method for identifying objects includes at least one tag having encoded information attached to the surface of an object to be identified, wherein the tag includes a first FSS-based elliptical polarization filter which provides the encoding.

Abstract: An integrated sub-millimeter and infrared reflectarray includes a reflective surface, a dielectric layer disposed on the reflective surface, and a subwavelength element array and a subwavelength element array electromagnetically coupled to the reflective surface. The subwavelength element array includes (i) electrically conductive subwavelength elements on the dielectric layer, (ii) wherein the dielectric layer comprises a plurality of dielectric subwavelength elements, or (iii) the dielectric layer includes a plurality of embedded dielectric subwavelength elements. The array includes at least one of a plurality of substantially different inter-element spacings and a plurality of substantially different dimensions for the elements.

Abstract: An optical combination includes a substrate, a linear polarizer on the substrate, and a first frequency selective surface (FSS) based elliptical polarization filter on the linear polarizer. The first FSS comprises at least one periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing orientated along a first axis. The pattern is operable to impose a phase differential for one orthogonal linear polarization state relative to the other linear polarization state for electromagnetic radiation having a wavelength between 400 nm and 1 mm, such as 1 ?m to 12 ?m. An identification system and associated method for identifying objects includes at least one tag having encoded information attached to the surface of an object to be identified, wherein the tag includes a first FSS-based elliptical polarization filter which provides the encoding.

Abstract: Hybrid microantennas and improved sensor structures incorporating hybrid microantenna embodiments are described herein. A hybrid long-wave infrared (LWIR) microantenna includes four inner pie-shaped arms in which the four inner pie-shaped arms are in a double bow-tie configuration and a plurality of outer pie-shaped arms in which a subset of the outer pie-shaped arms is connected to the four inner pie-shaped arms and the pie-shaped arms are sensitive to electric fields and absorb radiation.

Abstract: Hybrid microantennas and improved sensor structures incorporating hybrid microantenna embodiments are described herein. A hybrid long-wave infrared (LWIR) microantenna includes four inner pie-shaped arms in which the four inner pie-shaped arms are in a double bow-tie configuration and a plurality of outer pie-shaped arms in which a subset of the outer pie-shaped arms is connected to the four inner pie-shaped arms and the pie-shaped arms are sensitive to electric fields and absorb radiation.

Abstract: An integrated sub-millimeter and infrared reflectarray includes a reflective surface, a dielectric layer disposed on the reflective surface, and a subwavelength element array and a subwavelength element array electromagnetically coupled to the reflective surface. The subwavelength element array includes (i) electrically conductive subwavelength elements on the dielectric layer, (ii) wherein the dielectric layer comprises a plurality of dielectric subwavelength elements, or (iii) the dielectric layer includes a plurality of embedded dielectric subwavelength elements. The array includes at least one of a plurality of substantially different inter-element spacings and a plurality of substantially different dimensions for the elements.

Abstract: A circular polarizer (CP) includes an electrically insulating or semiconducting and optically transparent layer having a frequency selective surface (FSS) disposed thereon, the FSS includes a periodic array of electrically conductive spirals. For reflection mode operation, an electrically conducting substrate or ground plane layer preferably having a thickness of approximately one-quarter wave at the nominal design wavelength is disposed beneath the optically transparent layer.

Abstract: A small array of antenna-coupled infrared bolometer detectors is connected in parallel. This small array is suitable as an individual area-receiving pixel of an infrared focal plane array. These pixels will have better coupling efficiency to extended sources than are possible with individual antenna-coupled sensors, which have a spatial response on the order of one wavelength in dimension. This pixel can be used to provide the advantages of antenna-coupled IR sensors (e.g., fast response, wavelength tuning, and polarization tuning) while increasing the collection efficiency of the sensors to non-laser sources. When integrated into focal plane arrays, these detectors can be used in remote-sensing systems to facilitate enhanced image recognition, feature extraction and image-clutter removal.