Abstract: An apparatus includes a dielectric tile array including a plurality of dielectric tiles; and a plurality of electroactive (EA) material blocks configured to expand or contract in response to being actuated by the application of an actuation voltage.

Abstract: An electrically controllable RF circuit that includes an EC cell and an EAP-based actuator configured to produce relative movement of an electrode of the electrochromic cell and an electrically conducting patch or another electrode electromagnetically coupled thereto. In one embodiment, the RF circuit operates as a tunable patch antenna whose frequency characteristics can be changed by changing the bias voltages applied to the EC cell and EAP-based actuator. Advantageously, the capability to tune the antenna using two different tuning mechanisms (i.e., a dielectric-permittivity based tuning mechanism implemented using the EC cell and a geometry-based tuning mechanism implemented using the EAP-based actuator) provides more degrees of control over the pertinent antenna characteristics compared to what is available in some other antenna designs.

Abstract: An apparatus includes a dielectric tile array including a plurality of dielectric tiles; and a plurality of electroactive (EA) material blocks configured to expand or contract in response to being actuated by the application of an actuation voltage.

Abstract: An electrically controllable RF-circuit element that includes at least one layer of an electrochromic material sandwiched between two corresponding layers of a solid-electrolyte material and placed adjacent and along a length of RF transmission line. In one example embodiment, the electrically controllable RF-circuit element operates as a tunable band-stop (e.g., notch) filter whose stop band can be spectrally moved by changing one or more dc-bias voltages applied across the corresponding layer stack(s). In another example embodiment, the electrically controllable RF-circuit element operates as a tunable phase shifter whose phase-shifting characteristics can be changed by changing one or more dc-bias voltages applied across the corresponding layer stack(s).

Abstract: An electrically controllable RF circuit that includes an EC cell and an EAP-based actuator configured to produce relative movement of an electrode of the electrochromic cell and an electrically conducting patch or another electrode electromagnetically coupled thereto. In one embodiment, the RF circuit operates as a tunable patch antenna whose frequency characteristics can be changed by changing the bias voltages applied to the EC cell and EAP-based actuator. Advantageously, the capability to tune the antenna using two different tuning mechanisms (i.e., a dielectric-permittivity based tuning mechanism implemented using the EC cell and a geometry-based tuning mechanism implemented using the EAP-based actuator) provides more degrees of control over the pertinent antenna characteristics compared to what is available in some other antenna designs.

Abstract: An electrically controllable RF-circuit element that includes at least one layer of an electrochromic material sandwiched between two corresponding layers of a solid-electrolyte material and placed adjacent and along a length of RF transmission line. In one example embodiment, the electrically controllable RF-circuit element operates as a tunable band-stop (e.g., notch) filter whose stop band can be spectrally moved by changing one or more dc-bias voltages applied across the corresponding layer stack(s). In another example embodiment, the elecyrically controllable RF-circuit element operates as a tunable phase shifter whose phase-shifting characteristics can be changed by changing one or more dc-bias voltages applied across the corresponding layer stack(s).

Abstract: We disclose an electrically controllable RF-circuit element that includes an electrochromic material. In an example embodiment, the electrically controllable RF-circuit element is configured to operate as a phase shifter whose phase-shifting characteristics can be changed using a dc-bias voltage applied to a multilayered structure containing a layer of the electrochromic material.

Abstract: We disclose an electrically controllable RF-circuit element that includes an electrochromic material. In an example embodiment, the electrically controllable RF-circuit element is configured to operate as a phase shifter whose phase-shifting characteristics can be changed using a dc-bias voltage applied to a multilayered structure containing a layer of the electrochromic material.

Abstract: A disclosed electrical cell enables experimental measurements of dielectric properties of an electrochromic material in the radio-frequency range of the electromagnetic spectrum. In an example embodiment, the electrical cell includes a layer of the electrochromic material under test that is sandwiched between a conducting base plane and a microstrip line. The conducting base plane and the microstrip line are electrically connected to a co-planar waveguide configured for application of superimposed DC-bias and RF-probe signals using a conventional probe station and a vector network analyzer. The S-parameters of the electrical cell measured in this manner can then be used, e.g., to obtain the complex dielectric constant of the electrochromic material under test as a function of frequency.

Abstract: A disclosed electrical cell enables experimental measurements of dielectric properties of an electrochromic material in the radio-frequency range of the electromagnetic spectrum. In an example embodiment, the electrical cell includes a layer of the electrochromic material under test that is sandwiched between a conducting base plane and a microstrip line. The conducting base plane and the microstrip line are electrically connected to a co-planar waveguide configured for application of superimposed DC-bias and RF-probe signals using a conventional probe station and a vector network analyzer. The S-parameters of the electrical cell measured in this manner can then be used, e.g., to obtain the complex dielectric constant of the electrochromic material under test as a function of frequency.

Abstract: We disclose an electrically controllable RF-circuit element that includes an electrochromic material. In an example embodiment, the electrically controllable RF-circuit element is configured to operate as a phase shifter whose phase-shifting characteristics can be changed using a dc-bias voltage applied to a multilayered structure containing a layer of the electrochromic material.

Abstract: A new electro-optic sampling probe with femtosecond resolution suitable for ultra-fast electro-optic sampling. The new probe is several times thinner and has a dielectric constant four times less than the best reported conventional bulk LiTaO.sub.3 probes. In addition, the ultimate bandwidth is 50 percent greater than an equivalent LiTaO.sub.3 probe. The probe is a thin film of Al.sub.x Ga.sub.1-x As used in both total internally reflecting and free-standing geometries. Here x is chosen for sufficient transmission of the crystal to the wavelength of the laser source being used for electro-optic sampling. The thickness of the film is a small fraction of the thickness of prior art probes and is chosen, for speed and sensitivity of electro-optic sampling, to be thin compared to the spatial extent of the laser pulse. The thin film probe eliminates many of the problems associated with the use of bulk crystals as electro-optic sensors.

Abstract: This invention embodies p-n junction devices comprising Group III-V compound semiconductors in which the p or n or both p and n regions are formed by a superlattice selectively doped with an amphoteric Group IV element dopant selected from carbon, germanium and silicone. The superlattice includes a plurality of periods, each including two layers. Depending on the conductivity type, only one of the layers in the periods forming the superlattice region of said type of conductivity is selectively doped with said dopant, leaving the other layer in these periods undoped. The superlattice is formed by Molecular Beam Epitaxy technique, and the dopant is incorporated into respective layers by delta-doping as in a sheet centrally deposited between monolayers forming the respective layers of the period. Each period includes 5 to 15 monolayers deposited in the two layers in a numerical ratio corresponding to a cation compositional ratio in the compound semiconductor. Low growth temperatures, e.g. ranging from 410.

Abstract: It has been found that in the preparation of devices having repetitive layers, such as distributed Bragg reflectors, the dopant introduced during processing redistributes itself in a deleterious manner. In particular, this dopant through various effects segregates and diffuses from one layer into the interface region of the second layer. As a result, properties such as electrical resistance of the structure become unacceptably high. By utilizing various expedients such as carbon doping this segregation and its associated deleterious effects are avoided.

Abstract: Optically transparent and electrically conductive cadmium tin oxide or indium tin oxide is employed in vertical cavity surface emitting lasers for vertical current injection. Continuous wave lasing at room temperature is achieved in GaAs/AlGaAs quantum well lasers. Devices with a 10 .mu.m optical window which also serves as a vertical current injection inlet give lasing threshold currents as low as 3.8 mA. The differential series resistance is (350-450) .OMEGA. with a diode voltage of (5.1-5.6) V at the lasing threshold. Far field pattern of the laser emission is Gaussian-like with a full width at half maximum of 7.degree..

Abstract: This invention is a semiconductor vertical cavity surface emitting laser comprising a lasing cavity with an active layer, a bottom (rear) mirror and a top (front) mirror, and a front and rear electrodes for applying excitation current in direction substantially parallel to the direction of optical propagation. In accordance with this invention the front mirror comprises a thin, semitransparent metal layer which also acts as the front electrode. The metal layer is upon a highly doped layer forming a non-alloyed ohmic contact. The metal is selected from Ag and Al and is deposited in thickness ranging from 5 to 55 nm. The VCSEL is a semiconductor device wherein the semiconductor material is a III-V or II-VI compound semiconductor. For a VCSEL with GaAs active layer, the light output from the front metal mirror/electrode side yields a high external differential quantum efficiency as high as 54 percent. This is the highest quantum efficiency obtained in VCSEL structures.

Abstract: A process is described for making semiconductor devices with highly controlled doping profiles. The process involves minimizing or eliminating segregation effects caused by surface electric fields created by Fermi-level pinning. These electric fields act on dopant ions and cause migration from the original deposition site of the doplant ions. Dopant ions are effectively shielded from the surface electric fields by illumination of the growth surfaces and by background doping. Also, certain crystallographic directions in certain semiconductors do not show Fermi-level pinning and lower growth temperatures retard or eliminate segregation effects. Devices are described which exhibit enhanced characteristics with highly accurate and other very narrow doping profiles.