Abstract: Ferromagnetic nanoparticles which are converted from paramagnetic, antiferromagnetic, ferrimagnetic or weak ferromagnetic nanoparticles by incorporation of a dopant, the dopant having a concentration less than 0.5%. Major changes occur in the magnetic properties of the host material. A weak paramagnetic material such as Mn3O4 is been converted to a ferromagnetic material that has a Curie point beyond 700° C. and shows almost temperature independent coercivity and magnetic moment. These ferromagnetic nanoparticles can be used as contrast agent, as a vehicle for targeted drug delivery, high temperature magnets, high density magnets, magnetic circuits and many more devices utilizing local interaction of the magnetic field.

Abstract: A system and method for forming a beam and creating nulls. The inventive method combines frequency domain suppression technology for narrow-band jammer rejection with orthogonal weighting using Eigen analysis for jammer nulling and signal beam-forming for an array antenna system. The inventive system is adapted for use with an adaptive array antenna having a plurality of radiating elements. The system includes a frequency domain suppressor connected to the array antenna and an orthogonal weighting subsystem connected to the frequency domain suppressor. In the illustrative implementation, signals received by each radiating elements are processed by an analog front-end and digitized. The frequency domain suppressor includes a Fast Fourier transformer (FFT) and a frequency domain suppressor for each element in the array. The frequency domain suppressor further includes a threshold evaluator which reads the signals output by the FFT's and provides threshold controls to the spectral suppressors.

Abstract: A system and method for forming a beam and creating nulls. The inventive method combines frequency domain suppression technology for narrow-band jammer rejection with orthogonal weighting using Eigen analysis for jammer nulling and signal beam-forming for an array antenna system. The inventive system is adapted for use with an adaptive array antenna having a plurality of radiating elements. The system includes a frequency domain suppressor connected to the array antenna and an orthogonal weighting subsystem connected to the frequency domain suppressor. In the illustrative implementation, signals received by each radiating elements are processed by an analog front-end and digitized. The frequency domain suppressor includes a Fast Fourier transformer (FFT) and a frequency domain suppressor for each element in the array. The frequency domain suppressor further includes a threshold evaluator which reads the signals output by the FFT's and provides threshold controls to the spectral suppressors.

Abstract: A drive shaft locking mechanism including a locking structure in the form of a gear which is secured to an input shaft of a rotary tool, a retractable interlocking mechanism which selectively couples to the locking structure, and a directional control mechanism coupled to the interlocking mechanism, controlling its movement. The locking structure comprises at least one engageable surface and a means for securing the locking structure to the input shaft. The interlocking mechanism includes a locking element slidably disposed within a tubular channel and selectively extensible therefrom at the urging of the directional control mechanism, to engage the locking structure along an engageable surface.

Abstract: Optical sources, such as electro-absorption modulator isolated laser modules (EMILMs), for fiber optical communication systems are selected based on noise measures made outside—and preferably substantially outside—of the communication system's operational bandwidth. In one embodiment, EMILM devices are selected for communication systems having path lengths of 640 km or more based on both the chirp of the devices and the relative intensity noise (RIN) of the devices at the relaxation oscillation frequency Fr. Devices having both low chirp and low RIN at Fr are more likely to meet bit error rate requirements than are devices selected solely for low chirp.

Abstract: A semiconductor device is provided with at least two photodetectors and an interposed etalon. Signals from the photodetectors may be compared to generate a control signal. The control signal may be used for wavelength control and/or stabilization and for other purposes. According to a preferred embodiment, the etalon is formed of at least two distributed Bragg reflectors. The etalon provides high discrimination power. In addition, the etalon has a periodic discrimination function that may be matched to the periodic channels of a dense wavelength division multiplexing system. According to one aspect of the invention, electrical current may be applied to selected layers of the device to tune and/or shift the response of the device. If desired, the invention may be incorporated into a waveguide structure, such as an optical fiber. The present invention also relates to a wafer fusion technique for making integrated devices.

Abstract: A battery-powered driver tool has a tool housing with a socket-type coupler which receives a plug-type coupler of a battery pack in any of four different rotational orientations. Four keys on the battery pack are received in four keyways on the tool housing for non-rotatable engagement, the parts being retained by a split snap ring on the battery pack which cams past four cam shoulders on the tool housing, so that the parts automatically snap-engage and disengage in response to a simple push-pull motion. The battery pack includes a plurality of battery cells connected in series between positive and negative terminals which are designed to respectively engage positive and negative terminals on the tool housing in any of the four rotational orientations of the battery pack. The battery pack has a flat base surface, the parts being designed so that the tool/battery pack combination can be stood on the base surface in one rotational orientation of the battery pack.

Abstract: A pneumatic impact power tool has a tool body with a bit-receiving axial bore in its end surface. A cap is threaded on the end of the tool body and has an end wall spaced from the end surface to define a cavity and a lobed opening in the cavity matably receiving a like-lobed bit shank, the cavity being dimensioned to accommodate the lobes. Spring-biased balls project into the cavity from radial bores in the end cap to engage the shank lobes and bias them to a rotational position non-aligned with the opening lobes to inhibit removal. The cavity is dimensioned to afford a slight axial clearance to accommodate axial movement of the lobes. A cover on the end cap is recessed to receive the bias springs, retaining both the springs and the cover in place. The end cap has a annular channel communicating with an exhaust passage in the tool body and four exhaust ports in the end wall.

Abstract: A pneumatic scraping tool includes a pneumatic hammer assembly including a cylinder in which a piston reciprocates for repeated impact against an anvil or blade holder which is rotatably received within an end of the cylinder and carries a scraping blade. The anvil has an annular flange which stops its insertion in the cylinder, and is retained in place by a nut threadedly engaged with the cylinder and having an end wall spaced from the cylinder end a distance slightly greater than the flange thickness to permit reciprocation of the anvil. Exhaust air passes along a groove in the outer surface of the cylinder to an annular chamber in the nut and thence through four exhaust ports exiting at the end wall of the nut. A plug portion of the anvil projects through a central opening in the nut end wall and is received into a socket in a blade housing. Blade fingers project laterally into the socket.

Abstract: A process and apparatus for rapidly and accurately forming corrugated substructures of complex shapes utilizing composite material A plurality of movable elongated ribs are positioned on a base plate for lateral movement between an open position at which all of the ribs are physically separated and a closed position at which each of the ribs is engaged with its adjacent rib or ribs. The ribs are so formed that when they collectively assume the closed position, upper regions of the ribs remain spaced apart to define longitudinally extending channels. A pre-cut sheet of composite prepreg material is laid over the ribs so as to be coextensive with them. The ribs are then moved together mechanically or by means of vacuum drawing the sheet material into the channels or both. With the aid of elongated tooling bars placed on the outer surface of the sheet material and aligned with successive channel s, the sheet material is drawn into conforming relationship with the ribs.

Abstract: A reflection filter is disposed on a solid state laser so as to preferentially reflect TE or TM modes and to suppress oscillation within the resonator of the non-reflected modes. In one embodiment, the filter includes a layer having a plurality of grooves which may be straight and parallel or curved to approximate the mode shape. In another embodiment, the filter includes a polarization sensitive film, without grooves, which either absorbs or transmits the undesired mode. Specifically described is a buried heterostructure semiconductor DFB laser with such a reflection filter formed on at least one facet thereof.

Abstract: A nondestructive method is proposed for measuring stripe dimensions in order to grade light-emitting structures such as lasers. The width of the near-field emission parallel to the stripe is measured while the laser is operating below threshold. This measurement is correlated with the actual stripe width and with the possibility of kinks developing in the light output. The width of the far-field emission perpendicular to the junction plane can also be measured, and the product of the two widths can be correlated with the stripe area and the possibility of kinks in the laser output.

Abstract: Prior to packaging, semiconductor lasers are purged by being subjected first to high temperature and high current simultaneously so as to suppress stimulated emission and stress the shunt paths which allow leakage current to flow around the active region. A prudent, but nonessential, second step is to lower the temperature and/or current so that the lasers emit stimulated emission (preferably strongly, near the peak output power), thereby stressing the active region. Lasers subjected to such a purge exhibit stabilized degradation rates in short times (of the order of a few hours) and provide a robust population which meets the performance criteria of long lifetime systems.

Abstract: The property of Group III-V compound materials, whereby ion bombarded material becomes highly resistive but recovers its original low resistivity by annealing at a temperature which is dopant and material dependant, is utilized to fabricate integrated circuits which include buried semiconductor interconnections or bus bars between devices.

Abstract: A method of producing patternable resistive regions in III-V compound semiconductor devices and a resulting device structure having improved current characteristics. III-V semiconductor substrates are irradiated with inert ions to produce a resistive region therein. At least one epitaxial layer is grown over the substrate while maintaining the resistive characteristics within the substrate. A second resistive region is then formed in at least the top epitaxial layer. This second resistive region is aligned with the first one in order to minimize current spread through the device.

Abstract: A TJS light emitting diode (laser or LED) comprises an isotype double heterostructure (DH) and a V-groove which penetrates the intermediate layer of the DH. The groove is filled with a region of semiconductor material which enables carrier injection to occur from the region into the intermediate layer, or conversely, depending on the relative bandgaps of the layer and region. Real-refractive index guiding by the groove is described.

Abstract: Semiconductor lasers and LEDs are described in which the pumping current is constrained to flow from a relatively narrow upper channel formed by a V-groove, which extends to a depth short of the active region, through a relatively wider lower channel bounded by high resistivity regions, which extend from at least that depth into or through the active region. Also described are devices in which the V-groove is refilled with semiconductor material.

Abstract: A double heterostructure light emitting semiconductor device is described wherein a narrow bandgap active region is sandwiched between two wider bandgap cladding layers, one of which contains a p-n homojunction. The purpose is to separate the p-n junction from the active region and, thus, to have the active region bounded by two isotype (p-p or n-n) heterojunctions. This configuration significantly reduces nonradiative interface recombination current which occurs principally at the anisotype (p-n) heterojunction in a standard double heterostructure.

Abstract: A buried double heterostructure laser device isdescribed. A wafer of double heterostructure material is formed into narrow mesa stripes. A native oxide coating is formed on the side walls of the mesa. Semiconductor material having an index of refraction which is closely matched to the index of the active region is deposited over the mesa structure. High resistivity polycrystalline material forms on the native oxide and monocrystalline material forms on the top of the mesa. Vertical carrier and optical confinement is achieved by the higher bandgap cladding layers of the double heterostructure configuration. The native oxide acts as an electrical insulator to confine pumping current to the mesa. The closely matched polycrystalline material confines light parallel to the junction plane and prevents excitation of higher order transverse modes. Devices have been fabricated which exhibit cw threshold currents at room temperature as low as 55 mA.