Abstract: In an embodiment, an N.times.N integrated optical interconnection apparatus capable of switching, multiplexing or demultiplexing a large number of input and output wavelength channels achieves low levels of crosstalk and insertion loss. Two substantially identical N.times.M star couplers are connected by an optical diffraction grating comprising M unequal length waveguides spaced from one another by predetermined amounts. The waveguides of the grating consists of an array of curved waveguides of different lengths. The waveguides are closely spaced at their ends and widely spaced and strongly curved in the central region. The curves or bends of the planar waveguides here disclosed have sharper bends, lower losses and increased tolerance to fabrication defects.

Abstract: This invention is directed toward joining an optical fiber to a waveguide on a silicon or silica substrate. In a preferred embodiment, a discontinuity such as a notch is provided in the substrate along each side of a waveguide. The notches, which extend back from the end of each waveguide form air gaps between the ends of adjacent waveguides. Now, when an optical fiber is butt coupled to a waveguide on a substrate with adhesive, the notches at either side of the waveguides prevent adhesive from flowing along the edge of the substrate and onto the end of an adjacent waveguide. In addition, the adhesive flows around and encapsulates the substrate projections defined by the notches along the ends of the waveguide to provide a sturdy butt connection.

Abstract: An integrated optic device useful as a planar lens or a low order array multiplexer comprises a pair of optical couplers and an array of plural waveguides extending between the couplers in an "S" configuration to provide closely spaced optical path lengths. An "S" configuration provides equal path lengths for an optical lens. Incremental lengths added to the "S" in the region between curve reversal can provide small path length increments for a low order array multiplexer or demultiplexer.

Abstract: This invention is directed toward joining, with glass, a waveguide supported by a substrate to an optical fiber. In a preferred embodiment, a glass material which melts at a temperature that is lower than the temperature to which the waveguide can be safely heated is applied to either the optical fiber and/or the waveguide. The glass material is then heated to cause it to connect the optical fiber to the waveguide. A feature of the invention is the presence of heat breaks in the substrate upon which the waveguide resides to thermally isolate the end of each waveguide and the underlying substrate from adjacent waveguides and the portions of the substrate which underlie said adjacent waveguides. The heat breaks restrict heat from being conducted along the end of the substrate from one waveguide region to adjacent waveguide regions when heat is being applied to make a connection.

Abstract: An N.times.N integrated optical interconnection apparatus capable of switching, multiplexing, or demultiplexing a large number of input and output wavelength channels achieves low levels of crosstalk and insertion loss. Two substantially identical N.times.M star couplers are connected by an optical diffraction grating comprising M unequal length waveguides spaced from one another by predetermined amounts. Each coupler comprises a dielectric slab defining a free space region between two periodic arrays of waveguides, each radially directed toward a virtual focal point. The arrays are configured so that their respective foci are located at a predetermined distance away from and outside the free space region to minimize phase errors caused by mutual coupling between adjacent waveguides. Specifically, the focal point of each array connected to each star coupler may be located so that it coincides with the phase center of the other array connected to each coupler.

Abstract: A waveguide array comprising a plurality of waveguides which are each outwardly tapered at the aperture of the array in accordance with a predetermined criteria chosen to increase waveguide efficiency. The tapering serves to gradually transform a fundamental Bloch mode, propagating through the waveguide array, into a plane wave in a predetermined direction, and then to launch the plane wave into free space in the predetermined direction. In another embodiment, the waveguides are positioned relative to one another in order to satisfy the predetermined criteria.

Abstract: This invention is an optical Multiplexer/Demultiplexer, built from a plurality of optical waveguides. Each waveguide differs in length from its neighboring waveguide by a predetermined amount. The waveguides are strongly coupled to one another at their respective ends, and substantially uncoupled therebetween, allowing for high efficiency.

Abstract: An efficient N.times.N star optical coupler suitable for mass production in integrated form is disclosed. The coupler can be realized using silicon technology to form a dielectric coupler slab and two arrays of strip waveguides all on a single glass substrate. Power transfer betwen the two arrays is accomplished through radiation in the dielectric slab with theoretical efficiency exceeding 30% under optimized conditions.

Abstract: The present invention relates to an antenna comprising a plurality of feeds, and either a single reflector or a single lens wherein the reflector or lens includes a predetermined curved major surface that produces a maximum field of view in a first one of two principal planes of the antenna. The major curved surface is designed to produce a first and a second "stigmatic" focal point, which are spaced apart by a predetermined amount on either side of an axis normal to the center of the reflector or lens in the first principal plane, such that the coefficient of astigmatism is at a maximum predetermined tolerable amount at the center and at the opposite edges of the maximum field of view to produce a peanut-shaped area where the coefficient of astigmatism is within tolerable limits.

Abstract: A terrestrial radio system which utilizes spot beams, time division multiple access and frequency reuse to provide communications services from a base station to remote customers within a system service region. The base station advantageously is arranged with multistage switching so as to permit the respective sharing of radio transmitters and receivers over larger number of antenna transmitting and receiving ports.

Abstract: The present invention relates to an antenna arrangement for correcting for astigmatism is a beam which is linearly scannable in a first principal plane of the antenna arrangement. The antenna arrangement comprises a parabolic or torus main reflector and a feed arrangement for producing first and second astigmatic phase centers which lie along first and second focal lines, respectively, in the first principal plane and match first and second astigmatic phase centers required by the main reflector to produce a linearly scannable plane wave.

Abstract: The present invention relates to an antenna arrangement for reducing multipath fades. The antenna arrangement comprises a curved main reflector disposed confocally with one focal point of a subreflector, and a feed arrangement. The feed arrangement comprises at least a pair of feed horns and a selectively movable plate reflector disposed between the feed horns and the subreflector along a feed axis of the antenna arrangement. The feed horns are disposed adjacent each other with the aperture of each of two feed horns covering one-half of the image of the main reflector. By selectively orienting the plate reflector so that one of the two multipath beams arrives with its central ray disposed orthogonal to the aperture of the feed horns, the contribution from each half of this beam received at each feed horn, for a particular frequency band, is equal and can be subtracted from the other half beam signal to cancel its effect without the need for an equalizer.

Abstract: The present invention relates to a horn antenna which provides minimized cross-polarization in the far field of the antenna. The antenna arrangement comprises a horn including four walls wherein a first pair of opposing concentric conic walls are associated with a common longitudinal axis, and a second pair of opposing planar walls are aligned radially to the common longitudinal axis of the cones. The walls taper down from an offset parabolic main reflector to intersect a common apex corresponding to a focal point of the main reflector. The longitudinal axis of the horn is arranged at a predetermined angle to the common longitudinal axis of the cones to minimize cross-polarization in either one or both of the TE.sub.01 or TE.sub.10 modes in the far field of the antenna.

Abstract: The present invention relates to an antenna feed arrangement capable of providing a zero reflection response at a first frequency of interest and a maximally flat response at a widely separated second frequency of interest. The feed arrangement comprises a smooth-walled waveguide section at a first end, a corrugated waveguide section at a second end designed to provide the zero response at the first frequency, and a quarter-wave transformer waveguide section disposed between the smooth-walled and corrugated waveguide sections designed to provide the maximally flat response at the second frequency. The quarter-wave transformer section comprises a plurality of N corrugated waveguide subsections, where N.gtoreq.2, which comprise corrugation depths corresponding to the corrugation depths in the corrugated waveguide section.

Abstract: The present invention relates to an antenna arrangement comprising a feed producing a predetermined feed aperture illumination and a plurality of sequentially arranged reflectors including a main reflector forming the aperture of the antenna arrangement. The present antenna arrangement also includes filtering means centered on a real focal point between two reflectors of the antenna arrangement. The filtering means is arranged to pass therethrough the central ray of a beam launched by the feed and for smoothing out discontinuities of the image of the feed aperture illumination in the area of the main reflector normally found without filtering. The main reflector is then made slightly oversize to intercept the smoothened-out image of the feed aperture illumination along a line which produces a predetermined level of edge intensity.

Abstract: The present invention relates to a multibeam antenna arrangement having minimal aberration of astigmatism and coma over a wide area of the focal surface of the antenna. The present antenna comprises a plurality of N reflectors arranged confocally in a sequence along a feed axis of the antenna and at least one feed disposed in the vicinity of a focal point on the focal surface. The reflectors and the at least one feed are further arranged to provide an equivalent centered antenna arrangement with the longitudinal axis of the feed corresponding to an equivalent axis of the centered arrangement for eliminating astigmatism. Coma is then eliminated by deforming two of the N reflectors in a predetermined manner.

Abstract: The present invention relates to an antenna arrangement which uses a large offset spherical main reflector to communicate with several, spaced-apart, remote locations. Large aberrations caused by the main reflector are corrected by a first subreflector forming a small image of the main reflector at a conjugate image surface and a second subreflector which is disposed at the image location and is shaped to correct for the aberrations caused by the main reflector. Such correction is, to a good approximation, frequency independent and provides aberration free operation at feeds adjacent each other and associated with remote locations having small differential angles of incidence on the center of the main reflector.

Abstract: The present invention relates to a multibeam antenna arrangement having minimal primary aberration of astigmatism and coma over a wide area of the focal surface of the antenna. The present antenna comprises a plurality of N reflectors arranged confocally in a sequence along a feed axis of the antenna and at least one feed disposed in the vicinity of a focal point on the focal surface. The reflectors and the at least one feed are further arranged to provide an equivalent centered antenna arrangement with the longitudinal axis of the feed substantially parallel to an equivalent axis of the centered arrangement for eliminating astigmatism. Primary coma is then eliminated by deforming two of the N reflectors in a predetermined manner.

Abstract: The present invention relates to an antenna feed arrangement for correcting for astigmatism caused by an offset main reflector. The feed arrangement comprises at least one feed element, a first and a second cylindrical reflector disposed along the feed axis of the antenna with corresponding axes across the reflecting surfaces thereof oriented orthogonal to each other, and a pair of plates comprising a conductive material which are disposed parallel to, and on either side of, the feed axis of the antenna to enclose the area between the at least one feed element and the first reflector while forming an aperture thereof within a predetermined distance from the second reflector.

Abstract: The present invention relates to antennas with a segmented reflecting surface for providing fully or partially overlapping beams from separate feeds associated with each segment without incurring cross-coupling between feeds and power loss. More particularly, a main reflector or a subreflector reflecting surface is segmented to provide separate images of the far field area of the antenna on separate focal surfaces in the vicinity of an original focal surface of a corresponding non-segmented antenna. Feeds disposed at essentially corresponding locations on each of the far field area images produced by each of the segments provide separate beam footprints which overlap each other in the far field area by a predetermined amount.