Abstract: A slow light system includes a substrate and a metal layer formed thereon, the metal layer having a graded grating structure formed at a surface thereof, wherein the grating depth of the grating structure is sized such that surface-plasmon polariton dispersion behavior of the grating structure differs at different respective locations along the grating structure. Different wavelengths of incident light waves can be slowed at the respective locations along the grating structure.

Abstract: A slow light system includes a substrate and a metal layer formed thereon, the metal layer having a graded grating structure formed at a surface thereof, wherein the grating depth of the grating structure is sized such that surface-plasmon polariton dispersion behavior of the grating structure differs at different respective locations along the grating structure. Different wavelengths of incident light waves can be slowed at the respective locations along the grating structure.

Abstract: An optical limiter structure which includes a limiter material preferably dissolved in a host. The limiter material is selected from substituted and unsubstituted phthalocyanines, naphthalocyanines, porphyrins, salts of these materials and mixtures thereof, whereas the host is selected from any material which can dissolve the limiter material to at least the extent of 0.1% by weight.

Abstract: This invention describes a nanometer scale interband lateral resonant tunneling transistor, and the method for producing the same, with lateral geometry, good fanout properties and suitable for incorporation into large-scale integrated circuits. The transistor is of a single gate design and operation is based on resonant tunneling processes in narrow-gap nanostructures which are highly responsive to quantum phenomena. Such quantum-effect devices can have very high density, operate at much higher temperatures and are capable of driving other devices.

Abstract: A type II multiple quantum well, 4 constituent active region, optically clad electrically pumped and optically pumped laser for emitting at a wavelength greater than or equal to about 2.5 microns is disclosed. The active region comprises one or more periods, each period further comprising a barrier layer, a first conduction band layer, a valence band layer and a second conduction band layer.

Abstract: A method and apparatus for producing the conductivity-mobility spectrum of an isotropic semiconductor material, and hence infer the mobility and concentration of carriers in the material. Hall voltage and material conductivity are measured at a plurality of magnetic field strengths, values of the spectrum estimated for each field strength, and the estimates numerically iterated to produce convergent values for the spectrum. In one embodiment, interim selected values of the spectrum are prevented from going negative, which increases the precision of the ultimate convergent values. In another embodiment, the iteration equations employ damping factors to prevent over-correction from one iteration to the next, thus preventing convergent instabilities. The preferred iteration is the Gauss-Seidel recursion.

Abstract: This invention describes a nanometer scale interband lateral resonant tunneling transistor, and the method for producing the same, with lateral geometry, good fanout properties and suitable for incorporation into large-scale integrated circuits. The transistor is of a single gate design and operation is based on resonant tunneling processes in narrow-gap nanostructures which are highly responsive to quantum phenomena. Such quantum-effect devices can have very high density, operate at much higher temperatures and are capable of driving other devices.

Abstract: This invention describes a nanometer scale interband lateral resonant tunneling transistor, and the method for producing the same, with lateral geometry, good fanout properties and suitable for incorporation into large-scale integrated circuits. The transistor is of a single gate design and operation is based on resonant tunneling processes in narrow-gap nanostructures which are highly responsive to quantum phenomena. Such quantum-effect devices can have very high density, operate at much higher temperatures and are capable of driving other devices.

Abstract: The present invention relates to novel optical devices operating in the infrared, based on indirect narrow-gap superlattices (INGS) as the active optical materials. The novel optical devices include (1) wideband all-optical switches, which combine small insertion loss at low light intensities with efficient optical switching and optical limiting at high intensities, and (2) wideband infrared detectors with high collection efficiency and low tunneling noise currents, suitable for use in longwave infrared focal plane arrays. INGS comprise multiple semimetal/semiconductor layers having compatible crystal symmetry across each heterojunction between a given semimetal and the adjoining semiconductor, wherein each semimetal layer sandwiched between semiconductor layers is grown thin enough that each semimetal layer becomes a semiconductor, and wherein each semiconductor layer is thin enough that there is coupling between adjacent semiconductor layers.

Abstract: A protective layer laser hardens an optical detector. The material for the rotective layer is Hg.sub.1-Y Cd.sub.Y Te, where Y is selected so that the band gap of the protective layer is higher than the expected energy level for photons impinging on the protective layer. Photons with energy levels lower than the band gap are transmitted by the protective layer while photons exceeding the band gap energy level are absorbed or reflected by the protective layer. A semiconductor junction can be formed on the opposite side of the substrate from a Hg.sub.X Cd.sub.X Te layer with a band gap lower than the expected energy level, so that photons transmitted through the substrate are absorbed in the Hg.sub.X Cd.sub.X Te layer and, therefore, detected at the junction. At sufficiently high intensities where detector damage could result, the protective layer switches so that the incident photons are either absorbed or reflected, thus protecting the detector from damage.

Abstract: A method of achieving inversion in solid-state rare-earth materials for blue-green laser operation. A XeF excimer laser is used to pump a matching transition in divalent ytterbium in a host material. The host material is co-doped with a trivalent ion such as praseodymium (Pr.sup.3+) so that energy transfer to the trivalent ion will take place. Laser action is then from the Pr.sup.3+ ion. Alternative matching absorption transitions also occur in the trivalent rare-earth ions of Tb, Dy, Ho, and Nd.

Abstract: A method for accurately determining the compensation density of n-type naw-gap semiconductors. A semiconductor sample is irradiated with laser pulses of a particular density and pulse width for a particular time length with the sample maintained at a low temperature to generate photo-excited carriers within the semiconductor sample. Photons of energy less than the energy gap, E.sub.g, but greater than, E.sub.g /2, generate carriers uniformly throughout the semiconductor via the nonlinear mechanism of two-photon absorption. Photo-Hall measurements are made on the semiconductor sample during and after the laser pulse to determine the mobility, .mu., and carrier density, n, as a function of time using suitable equipment such as a computer controlled digital processing oscilloscope to display the curves. The curves displayed by the oscilloscope are compared with previously calculated curves to obtain a match and thereby determine the quality of the sample.

Abstract: An efficient, four-level, blue-green, excimer-pumped laser which is opera at room temperature. The laser element includes a CaWO.sub.4 crystal which has been codoped with trivalent thulium activator ions and divalent ytterbium sensitizer ions. Energy is transferred from the absorbing Yb.sup.2+ ions to the Tm.sup.3+ ions and the laser transition is from the .sup.1 D.sub.2 multiplet to the ground .sup.3 F.sub.4 of the Tm.sup.3+ ion. This transition terminates on an excited state; therefore, the laser action is four-level.

Abstract: A method for determining the compensation density of narrow-gap semiconductors. Photo-excited carriers are generated by uniformily irradiating a sample with a laser pulse of a particular density and pulse width for a particular time length and at a low sample temperature. The laser wavelength is chosen with a photon energy sufficiently high that carriers are excited from the conduction band by normal intrinsic absorption (one-photon absorption). Subsequent to the laser pulse, conductivity-voltage measurements are taken as a function of time during the photo-electron decay. Such measurements are made for different applied source-detector connections on the same sample with identical pulse-time values for each different correction. The sample is then laser-pulsed as before with a magnetic field normal to the sample surface to obtain Hall-voltage measurements. The measurements are averaged for the same time duration and the average of all curves are used in the determination.

Abstract: Improvements in Praseodymium solid state YLF lasers operating in the blueeen spectral region at room temperature and providing short pulses useful for underwater communication and detection systems. A dye laser with a narrow spectral output matched to the absorption spectra of the solid state laser is provided as a laser pump. The Pr doped YLF crystal of the solid state laser is physically oriented so it can be longitudinally pumped by light polarized parallel to the c-axis of the crystal, and the solid state laser is equipped with special spectrally selective mirrors. The foregoing and other modifications of prior Pr solid state laser systems provide increased efficiency and power output.

Abstract: A method for determining in situ the thermal conductances of bonding layers of detectors in infrared detector arrays for quality selection of preferred detector arrays. Each detector of the array is heated successively by laser pulses of variable pulse width and the thermally-induced change in detector resistance is measured as a function of time after each laser pulse and converted directly to its corresponding temperature. Using measured values of detector resistance as a function of temperature for each detector, one can obtain the time-dependence of the detector temperature following each laser pulse for each detector of the array.

Abstract: A photoconductive detector comprising a thin film of photoconductive material deposited on a thin substrate of high thermal conductivity having a surface area that is large relative to the detector's absorbing surface area. The back surface of the substrate is metalized and soldered to a high-thermal-conductivity, large-thermal-mass heat buffer which is coupled to a heat sink. The resulting detector is hardened against damage resulting from laser irradiation.

Abstract: A method of determining thermal constants of bonding layers of an infrared ensor which comprises cooling a bonded layer sensor to 77.degree.K and then heating the sensor by a quick pulse of heat. The electrical resistance of the sensor is measured and the measurement continued to determine a thermal profile. The measured thermal profile is compared with a known profile to determine thickness of the bonding layers and the material layers.