Abstract: Inside a parallelepipedic guide section there is provided at least one partition located so as to divide the inner volume of the guide section into a main waveguide portion capable of supporting an orthogonally polarized signal and two secondary waveguide portions extending in the same direction as the main waveguide portion. The secondary waveguide portions are so dimensioned such that one of these waveguide portions is capable of supporting a horizontally polarized signal and that the second waveguide portion is capable of supporting a vertically polarized signal.

Abstract: A long phase-locked loop circuit is provided which has an electronic closure circuit in series in the loop. The loop is effectively an open loop until acquisition of the incoming signal at which time the electronic closure circuit closes the phase-locked loop. A novel coincidence circuit is provided which compares the carrier in the loop with a reference frequency and when the two frequencies are equal the coincidence circuit closes the electronic closure circuit.

Abstract: The invention relates to an operational amplifier, particularly for signal amplification requiring high accuracy and extremely high speed which includes bandwidth, slew rate and settling time. A current feedback can be implemented with a low impedance inverting input for an increased high frequency performance. The operational amplifier according to the present invention has an input stage providing a pair of output signals, thus preserving a differential nature of the input signal of the operational amplifier. A power amplifier means is coupled to the input stage for amplifying and converting the output signals thereof into a single output signal. A very high open loop gain and save phase margin are obtained with a low number of amplification stages as the input stage has inherently a high voltage gain and the output signals thereof are amplified separately, whereby the common base configuration is preferred.

Abstract: A semiconductor amplifying device 1 comprises, a substrate 2, a first optical waveguide 7 on the substrate 2 for transmitting an optical signal, a second optical waveguide 8 on the substrate 2, a third optical waveguide 11 on the substrate 2 forming an optical coupling with the first optical waveguide 7 along an interaction length and constructed as a semiconductor optical amplifier 11 that receives and amplifies at least a portion of the optical signal to the first waveguide 7, and antireflective means 16 covering light emitting edges 7a, 8a, 11a, 3a at corresponding ends of the respective waveguides 7, 8, 11 and an optical transmitting medium 3, the second optical coupling having a phase mismatch selected for a wavelength of the optical signal to provide for a power gain in the first optical waveguide 7 attributed to an amplified portion of the same wavelength of the optical signal coupled back from the amplifier 11.

Abstract: An amplifier suitable for use as an active filter such as a low-pass filter, a high-pass filter or a phase shifter, which can be easily formed as part of an integrated circuit. The amplifier includes first and second transistors, which together form a first differential amplifier for converting the voltage of the input signal thereto to a signal current. It also includes third and fourth transistors, which together form a second differential amplifier for dividing the signal current from the second transistor in a given ratio. A capacitor is connected to the collector of the fourth transistor, and first and second resistors are connected, respectively, to emitters of the first and second transistors. The current division ratio of the current flowing through the third and fourth transistors is controlled by a control voltage DC supplied to the base of the third transistor and the base of the fourth transistor.

Abstract: A crossover arrangement for optical conductors, each in the form of a rod of light-transmissive material, includes a multifaceted, e.g. polyhedral member having pairs of mutually parallel opposed facets. Each pair of facets extend in a direction transverse, preferably perpendicular, to that in which a second pair of facets extend. The end face of each optical conductor is abutted against one of the facets of the polyhedron. Each facet has a coating of a material having a lower refractive index than that of the polyhedron or the optical conductors. Light entering the polyhedron from one conductor passes across the polyhedron and into the opposite conductor, being constrained to stay within the polyhedron by the coatings on the side facets. Preferably the polyhedron member is a cube and the optical conductors are of square cross-sectional shape.

Abstract: An electrochromic display device in which an electrolyte is disposed between a display electrode and a counter electrode, and an electrochromic substance layer is formed at least to the inside of said display electrode, wherein the counter electrode comprises a layer containing a white redox substance. Since the white redox substance layer is formed to the counter electrode, white background plate is no more necessary which enables to reduce the fabrication cost and give a great feasibility for the design of ECD.

Abstract: An attenuator control arrangement for use in a frequency multiplexed communications system includes a light-dependent attenuating resistance which is controlled in normal operation by the level of a pilot tone, in the multiplexed signal being attenuated, being used to control a light-emitting diode which illuminates the light-dependent resistance. A second light-dependent resistance also illuminated by the light-emitting diode is used to provide a control signal for the light-emitting diode in the event that the pilot tone is not detected, whereby a stable attenuation is provided in the absence of the pilot tone.

Abstract: A VOR antenna array with a plurality of radiating antenna elements spaced around and arranged on the periphery of an essentially circular path. The elements extend in the same direction around the periphery of the circular path and a central feed point is connected to the equivalent end of each radiating element by a feed-line to form a multi-sectored loop fed at the junction of each sector by in-phase sources.

Abstract: In a circuit layout for signal amplification with the aid of a differential amplifier and signal coupling via a first capacitor, it is proposed, in order to prevent unacceptable operating point displacements into the non-linear area of the amplifier layout in the event of temporarily interfering high-level signals, that one input of the differential amplifier connected to the signal source via the first capacitor be connected via a first resistor, and the other input via a second resistor, jointly via an electronic switch controllable by a comparator, to reference potential. A reference voltage source is connected to one input of the comparator, and the signal source to the other input of the comparator via an RC element, whose time constant is of the same order of magnitude as the time constant formed by the first capacitor and the first resistor.

Abstract: An electrically controlled integrated optical switch having a body made up entirely of crystalline silicon. More specifically, the body has a pair of channel waveguides intersecting in an X-like configuration forming therein an intersection crossover region. A first electrode is positioned on the intersection crossover region and a second electrode is positioned on the bottom of the body opposite the intersection crossover region. A controllable current/voltage source is electrically connected to the electrodes in order to alter the index of refraction of the intersection crossover region by carrier injection in order to selectively switch optical signals between diverging waveguides.

Abstract: A mounting arrangement for mounting an optical conductor on a "photonic" backplane provides for simple, accurate positioning during installation and easy access to, and removal of, the optical conductor when in service. The optical conductor constitutes a "busbar" in that it has a series of reflector surfaces spaced along its length to permit distribution or aggregation of several light signals. In one embodiment, an individual support is provided at each reflector/circuit card location. Each support is a seating member which houses a lens to couple light between the optical conductor and the circuit card. In another, preferred, embodiment the optical conductor is housed in a channel in a guide rail mounted upon the backplane. Separate cover members are releasably mounted upon the guide rail adjacent each circuit card. Each cover member has an aperture and lens to couple light between the reflector and the circuit card.

Abstract: To make a low loss connection between the core (5) of a single mode optical fibre (1) and a waveguide (2) on a waveguide substrate (3), a support block (4) which straddles the waveguide (2) is mounted on the waveguide substrate (3). The end-face (6) of the optical fibre (1) is fixed to both the waveguide substrate (3) and the support block (4) with transparent, light curable, adhesive (8). The support block (4) may be affixed to the substrate (3) with the same adhesive as is used to fix the optical fibre (1) to the substrate (3).

Abstract: A coupling device for forming optically efficient end-to-end connections between optical fibers having a common core and cladding geometry but different relative dimensions and cross sections includes forming a segment of optical fiber having the same general geometry of the fibers to be coupled but which varies between relatively enlarged and reduced cross sections along its length. The coupling device is severed along its length at appropriate points to match the relative cross sections of each fiber to be coupled to thereby allow a butt type coupling between optical fibers of the same general geometry but with differing cross sectional areas. The coupling devices may be manufactured by drawing a starting fiber having the same geometry of the fibers to be coupled and varying the drawing speed to create enlarged and reduced cross section portions. The starting fiber may then be severed at the reduced cross section portions to provide the coupling device.

Abstract: To increase the dynamic ratio of an amplifier, it is preceded by a switchable attenuator which is switched on when the output voltage of the amplifier exceeds a threshold, this output voltage being added to a shifting voltage.

Abstract: A frequency response compensation circuit includes a first forward gain stage and second reverse gain stage coupled to the first stage in negative feedback mode. The reverse gain stage depresses the gain of the first stage at low frequencies. When the frequency response of the reverse gain stage begins degrading, which corresponds to the frequency of the real zero of the compensation circuit, the gain of the compensation circuit begins increasing and increases until the gain of the reverse stage is zero. The circuit utilizes a pair of NPN transistors in the first stage, a pair of PNP transistors in the second stage and includes no capacitors or inductors. Thus, the circuit can be implemented as a semiconductor integrated circuit. By proper selection of the resistance values of the resistors in the circuit, the zero of the compensation circuit can be chosen to correspond generally to the frequency of the pole of the uncompensated input signal, so as to increase the bandwidth of the resultant signal.

Abstract: An optical reading head is an optical reader for photoelectric reading of images on a medium, comprising a plural light-emitting optical fibers for transmitting beams of light from light emitting elements to the surface of the medium, and plural light-receiving optical fibers for transmitting beams of reflected light from the medium surface to light-sensitive elements. The ends of the light-emitting and light-receiving optical fibers opposite to the medium surface are positioned in first and second rows, respectively, at a predetermined pitch. The ends of the light-receiving optical fibers are displaced relative to the ends of the light-emitting optical fibers along the first and second rows by a distance equal to a half of the predetermined pitch. Also disclosed is an optical reader comprising the above-described optical reading head, and a control device for controlling the operations of the light emitting elements, so that the resolution of the reading head is variable in two steps.

Abstract: A plurality of millimeter wave power sources are arranged in a planar mat array located in a wave-beam resonator including two reflecting surfaces which are large in terms of the operating wavelength. One surface comprises a planar reflector located in relatively close proximity to the source array, while the other reflector is located in front of the array at a relatively larger distance and being partially transparent and curved, with the curvature being expressed by a pair of focal lengths which define a curvature in two perpendicular axial planes. Each source is comprised of an IMPATT or GUNN diode coupled to a short dipole or closed current loop structure, all lying in a plane parallel to the planar reflector and transverse to the longitudinal central axis of the resonator.

Abstract: A differential operational amplifier circuit, having an input stage and an output stage, is balanced--i.e., is designed to have zero common mode component in its output--by means of a common mode feedback loop arrangement. This arrangement includes a common mode detector, connected for detecting the common mode signal component in a pair of outputs of the output stage of the circuit, and a pair of current steering devices, connected for drawing equal currents from each of the outputs of the input stage. During operation, the common mode detector feeds back a suitable control signal to each of the current steering devices, whereby the common mode component in the outputs is substantially completely suppressed.

Abstract: Disclosed is a nonglaring mirror which is an electrochromic device in principle. The mirror comprises a transparent front substrate laid with a transparent first electrode film, a back substrate laid with a second electrode film which is opposite and spaced from the first electrode film, first and second electrochromic layers formed on the first and second electrode films, respectively, and an electrolyte liquid which fills up the space between the two substrates. A reflecting surface is provided by using a transparent sheet as the back substrate and coating the rear surface of the back substrate with a reflecting metal film, or by using a reflecting metal film as the second electrode film. One of the first and second electrochromic layers is formed of a polymer of a conjugated compound, such as substituted or unsubstituted triphenylamine, and the other is formed of a transition metal oxide such as WO.sub.3. In the initial state both the first and second electrochromic layers are colorless and transparent.