Abstract: A microelectromechanical (MEM) switch is fabricated inexpensively by using processing steps which are standard for fabricating multiple metal layer integrated circuits, such as CMOS. The exact steps may be adjusted to be compatible with the process of a particular foundry, resulting in a device which is both low cost and readily integrable with other circuits. The processing steps include making contacts for the MEM switch from metal plugs which are ordinarily used as vias to connect metal layers which are separated by a dielectric layer. Such contact vias are formed on either side of a sacrificial metallization area, and then the interconnect metallization is removed from between the contact vias, leaving them separated. Dielectric surrounding the contacts is etched back so that they protrude toward each other. Thus, when the contacts are moved toward each other by actuating the MEM switch, they connect firmly without obstruction.

Abstract: A multiple band reconfigurable reflecting antenna array and method for multiple band operation and beam steering. An array of dipole antennas is disposed on a multiple band high impedance surface. The antenna array is reconfigured by changing the length of the dipole elements, to thereby change the dipoles resonant frequency. At a given frequency band, small changes in dipole length allow to steer the reflected beam in the selected direction; whether large changes in dipole length permit to switch the operating frequency band. A method of broadening the bandwidth of a high impedance surface is also exposed.

Abstract: An optically controlled micro-electromechanical (MEM) switch is described which desirably utilizes photoconductive properties of a semiconductive substrate upon which MEM switches are fabricated. In one embodiment the bias voltage provided for actuation of the switch is altered by illuminating an optoelectric portion of the switch to deactuate the switch. In an alternative embodiment, a photovoltaic device provides voltage to actuate the switch without any bias lines at all. Due to the hysteresis of the electromechanical switching as a function of applied voltage, only modest variation of voltage applied to the switch is necessary to cause the switch to open or close sharply under optical control.

Abstract: Methods for the design and fabrication of micro-electro-mechanical switches are disclosed. Two different switch designs with three different switch fabrication techniques are presented for a total of six switch structures. Each switch has a multiple-layer armature with a suspended biasing electrode and a conducting transmission line affixed to the structural layer of the armature. A conducting dimple is connected to the conducting line to provide a reliable region of contact for the switch. The switch is fabricated using silicon nitride as the armature structural layer and silicon dioxide as the sacrificial layer supporting the armature during fabrication. Hydrofluoric acid is used to remove the silicon dioxide layer with post-processing in a critical point dryer to increase yield.

Abstract: A method and system for transmitting, and a signal comprising multiple frequency bands from a single slot antenna are disclosed. The system comprises a slot antenna and a micro-electro-mechanical (MEM) switch, coupled to the slot antenna. The MEM switch is opened and closed, thereby changing the resonant frequency of the slot antenna. The slot antenna transmits a first frequency when the MEM switch is open and a second frequency when the MEM switch is closed. The method for transmitting a first frequency and a second frequency from a slot antenna comprises the steps of transmitting the first frequency from the slot antenna, closing a micro-electro-mechanical (MEM) switch coupled across the slot antenna, therein changing the resonant frequency of the slot antenna, and transmitting the second frequency from the slot antenna after the MEM switch is closed.

Abstract: An optically controlled micro-electromechanical (MEM) switch is described which desirably utilizes photoconductive properties of a semiconductive substrate upon which MEM switches are fabricated. In one embodiment the bias voltage provided for actuation of the switch is altered by illuminating an optoelectric portion of the switch to deactivate the switch. In an alternative embodiment, a photovoltaic device provides voltage to actuate the switch without any bias lines at all. Due to the hysteresis of the electromechanical switching as a function of applied voltage, only modest variation of voltage applied to the switch is necessary to cause the switch to open or close sharply under optical control.

Abstract: A method and system for transmitting, and a signal comprising multiple frequency bands from a single slot antenna are disclosed. The system comprises a slot antenna and a micro-electro-mechanical (MEM) switch, coupled to the slot antenna. The MEM switch is opened and closed, thereby changing the resonant frequency of the slot antenna. The slot antenna transmits a first frequency when the MEM switch is open and a second frequency when the MEM switch is closed. The method for transmitting a first frequency and a second frequency from a slot antenna comprises the steps of transmitting the first frequency from the slot antenna, closing a micro-electro-mechanical (MEM) switch coupled across the slot antenna, therein changing the resonant frequency of the slot antenna, and transmitting the second frequency from the slot antenna after the MEM switch is closed.

Abstract: A photodetector is fabricated in a multilayer structure having a semi-insulating InP substrate, an n+ InP contact layer overlying the InP substrate, an undoped InGaAs absorbing layer overlying the n+ InP contact layer, and a p+ doped InGaAs layer overlying the undoped InGaAs absorbing layer. A gold-beryllium p-contact dot is deposited onto the p+ doped InGaAs layer of the multilayer structure. A mesa structure is etched with a citric acid-based etchant into the multilayer structure. The mesa structure includes the metal p-contact dot, the p+ doped InGaAs layer, and the undoped InGaAs absorbing layer. The n+ InP contact layer is patterned, and a passive metallic n-contact layer is deposited onto the patterned n+ InP contact layer. A polyimide insulator layer overlying a portion of the structure is deposited and patterned, so that the polyimide insulator layer does not cover the passive metal p-contact dot and the metallic n-contact layer.

Abstract: A substantially lossless transmissive link, such as an RF fiber optic link, that selectively employs a number of techniques to improve various link parameters. The link may be structured to comprise a high power light source, such as a laser, that provides light output having a high level of optical power. A feedback circuit may be disposed around the light source that reduces relative-intensity-noise levels produced by the light source at low frequencies. A modulator is provided that modulates the light output of the light source. Preferably, a dual output modulator may be used to provide two modulated optical signals whose respective RF modulation is “effectively” 180 degrees out of phase. An optical fiber that transmits the modulated optical signal(s). A photodetector without a load resistor directly on its output that is operable at the high level of optical power, receives the modulated light and recovers the RF signal.

Abstract: A multiband millimeterwave antenna system for communicating signals in multiple frequency bands is disclosed. A main antenna body is connected to antenna extensions by micro-electro-mechanical switches. By opening and closing the switches, the length of the antenna can be altered. The antenna is coupled to a microstrip feed line by an aperture. A series of matching stubs match the impedance of the feed line for the various signal frequencies.

Abstract: Methods for the design and fabrication of micro-electro-mechanical switches are disclosed. Two different switch designs with three different switch fabrication techniques are presented for a total of six switch structures. Each switch has a multiple-layer armature with a suspended biasing electrode and a conducting transmission line affixed to the structural layer of the armature. A conducting dimple is connected to the conducting line to provide a reliable region of contact for the switch. The switch is fabricated using silicon nitride as the armature structural layer and silicon dioxide as the sacrificial layer supporting the armature during fabrication. Hydrofluoric acid is used to remove the silicon dioxide layer with post-processing in a critical point dryer to increase yield.

Abstract: A reconfigurable filter system designed using micro-elecro-mechanical (MEM) switches is disclosed. The filter comprises a transmission line with one or more filter stubs coupled to the transmission line by MEM switches. The impedance of the filter system is altered by selectively opening and closing the MEM switches, which alters the filter characteristics of the filter system. Alternatively, the characteristics of the filter system are altered by using the MEM switches to selectively alter the length of filter stubs attached to the transmission line.

Abstract: A display includes a plurality of light-emitting devices arranged as a matrix of pixels and an addressing circuit coupled to each respective light-emitting device. The addressing circuit includes a plurality of micromachined electromechanical (MEM) switches operable to control the plurality of light-emitting devices. Each MEM switch includes a cantilever beam and a control electrode spaced therefrom to deflect the cantilever beam electrostatically in order to close or open the switch.

Abstract: A phased array radar system employs programmable microelectromechanical (MEM) switches and transmission lines to provide true time delays or phase shifts in order to steer the array beam. The array includes an excitation signal source, a power division network for dividing the excitation signal into a plurality of excitation signal components, a plurality of programmable time delay/phase shift circuits including the transmission lines and MEM switches, and a plurality of radiating elements. An adaptive controller provides the control signals to set the MEM switches and select the time delay/phase shift through each time delay/phase shift circuit, thereby steering the array beam to a desired direction.

Abstract: An optical receiver with an enhanced power capability and wide bandwidth is implemented by distributing a number of photodetectors along an optical transmission channel to convert respective portions of an optical signal into electrical signals. An electrical transmission line receives and accumulates signal inputs from the photodetectors. A velocity matching is established between the optical and electrical signals, allowing the photodetector outputs to accumulate coherently along the electrical transmission line, by loading the transmission line with distributed capacitance elements. The loading capacitances are preferably inherent in the photodetectors, which are designed and spaced apart from each other to yield the desired velocity matching.

Abstract: A spatial light modulator includes a photosensor diode and a photoemitting diode array, each having two semiconductive layers of opposite electrical polarities, and which are sandwiched together with layers of the same polarity (P or N) in electrical contact with each other. Transparent electrode layers are formed on the opposite surfaces of the photosensor diode and photoemitting diode array respectively, in electrical contact with the layers of the opposite polarity. The individual photoemitting diodes are electrically and optically isolated from each other. With a voltage applied across the electrodes which causes the photosensor diode to be reverse biased and the photoemitting diodes to be forward biased, the photoemitting diode array generates a visual display which is a reproduction of a light image incident on the photosensor diode. The photosensor diode may be replaced by a single layer of a photoconductive material.

Abstract: A method is provided for accelerating and improving the recovery of GaAs solar cells from the damage which they experience in space under high energy particle irradiation such as electrons, protons and neutrons. The method comprises combining thermal annealing with injection annealing. Injection annealing is the recovery from radiation damage resulting from minority carrier injection into the damaged semiconductor, nonradiative minority carrier combination of the injected minority carriers, transfer of the recombination energy to the crystal lattice and utilization of this energy to remove the defects caused by the high energy particle irradiation. The combined annealing of this invention is implemented by heating the solar cells to a moderate temperature (on the order of about 200.degree. C. to 300.degree. C.

Abstract: A method is provided for accelerating and improving the recovery of GaAs solar cells from the damage which they experience in space under high energy particle irradiation scuh as electrons, protons and neutrons. The method comprises combining thermal annealing with injection annealing. Injection annealing is the recovery from radiation damage resulting from minority carrier injection into the damaged semiconductor, nonradiative minority carrier combination of the injected minority carriers, transfer of the recombination energy to the crystal lattice and utilization of this energy to remove the defects caused by the high energy particle irradiation. The combined annealing of this invention is implemented by heating the solar cells to a moderate temperature (on the order of about 200.degree. C. to 300.degree. C.