Abstract: An optical coupler comprises at least one optical fiber (1), one laser (2), one photodiode (3), one focusing lens (30) for focusing on the fiber and one plate (41) which reflects the rays coming from the fiber (1) towards the photodiode (3). In order to prevent a ray sent out by the laser (2) from returning to the photodiode (3) after reflection on the input diopter (4) of the lens (30), the optical axis is broken at the height of this diopter (4) by means of a prism (5). The reflected rays do not return to the plate (41).

Abstract: The disclosure relates to integrated circuits of lasers, wherein the linear arrays are supplied in series, with a return of current through the substrate. When the substrate is semi-insulating, only the first epitaxially grown layer is conductive. To reduce its electrical resistance, a surface film of the substrate is made conductive by diffusion of a dopant. Application to power semiconductor lasers.

Abstract: The invention applies to a laser integrated circuit comprising at least one row of lasers (30) lying between two reflector strips (28). The lasers (18) are electrically connected in parallel. The light emission along the strip will be more uniform if the electrical current is distributed by two "combs" whose "teeth" are parallel to the laser ribbons (18) and interleaved with them. The terminal metallized area (44) for the first comb is deposited at the bottom of a recess (18) and the terminal metallized areas (45) for the second comb are on the surface of the row. Such a device finds particular application to the power supply for laser integrated circuits.

Abstract: The invention applies to a row of semiconductor lasers. To dissipate the heat generated during operation, this row of lasers is wired by a thick metal tape (11) brazed (points 12) to the mesas (9) which surround the laser cavities (2). The other electrical polarity is applied by the support plate (3) through the substrate (1).

Abstract: A method for the alignment of an optical fiber on the optical axis of a light-emitting or light-receiving semiconductor component uses only line contacts between the metal parts. With the component being fixed to a base provided with two grooves, and the fiber being provided with a sleeve, the position of the fiber is determined in polar coordinates by at least two plates which lie in grooves and form angles that are adjustable. The positions are fixed by laser soldering when the alignment is obtained. The device can be applied to optical heads.

Abstract: The disclosure relates to the field of optical components in which a fiber is aligned on a laser, LED or similar device. The fiber is fixed into a sleeve clamped by a "keyhole" shaped clamp. The optical component is fixedly joined to a base in which a slot is parallel to the optical axis of the component. The clips of the clamp are introduced into the slot which is designed to give three degrees of liberty. When the alignment is obtained in dynamic operation, the parts are fixed by solders made by laser. The device can be applied to optical heads.

Abstract: An optic head designed to be fitted into a hybrid circuit. This optic head includes at least one optoelectronic semiconductor assembly and one optic fiber in alignment. In order to attach it to a hybrid circuit, the elements are all mounted on a metal wafer which serves as a reference plane. The fiber is brazed or bonded to the wafer by means of a metal tube which supports a lens. Optic head has a second optoelectronic assembly also fixed to the metal wafer, a dichroic mirror or a semi-reflecting plate sends the light beam back to the second assembly. A filter may be provided to improve the separation of the light beams. The present invention finds application to multiplexers, demultiplexers, duplexers and optic couplers.

Abstract: A microwave integrated circuit having planar and mesa components and microstrip lines and method of making the same is disclosed. To preserve a constant impedance for the microstrip lines, the mesa component is buried in a recess, which is then filled with a dielectric having substantially the same thermal expansion coefficient and the same dielectric constant as the insulating substrate. The surface of the mesa component and of the dielectric is in the plane of the planar part of the integrated circuit. Between the interconnecting microstrip lines on the planar face and the ground plane on the face of the substrate, the thickness and the dielectric constant of the material is constant.

Abstract: The disclosure concerns semiconductor lasers in which the current has to be localized, preferably in the emissive strip. In a laser having at least one emissive strip and a contact for current injection, the current is localized on the strip by means of an overdoped well that goes through the confinement layer with doping gradient. This confinement layer is doped to a level of 10.sup.18 at.cm.sup.-3 in the vicinity of the strip and to a level of 2.10.sup.17 at.cm.sup.-3 in the vicinity of the injection contact. The disclosed device can be applied to telecommunications and data processing by optical fibers.

Abstract: A circuit for measuring the dynamic characteristics of encapsulating packages for high-speed integrated circuits includes at least two amplifiers integrated on a semiconductor substrate. These amplifiers have the same input and output impedances as those of the high-speed circuit to be encapsulated within the package. The amplifiers are located in widely spaced relation in order to ensure that there is no internal coupling. Depending on the measurements to be performed, the two amplifiers are mounted in parallel or in antiparallel relation. In order to measure the dynamic characteristics of a package, a measuring circuit is mounted within a package and a signal (V.sub.e) is addressed to an input connection of the package. The transmission and coupling coefficients are deduced from measurement of the signal (V.sub.S) collected on an output connection.

Abstract: In order to interconnect an unprotected bare chip of MMIC (microwave monolithic integrated circuit), a ceramic substrate carries a double-face circuit. A network of microstrip lines which radiate from the center to the periphery is disposed on the first face of said double-face circuit. The bare MMIC chip and its microwave environment is fixed on the second face which is metallized as a ground plane. The microwave circuit is interconnected with the network of microstrips by means of plugged metallized holes. A sole-piece provided with a housing for the MMIC is fixed on the ground plane. The first face can carry self-protected components.

Abstract: A microwave integrated circuit having planar and mesa components and microstrip lines. To preserve a constant impedance for the microstrip lines, the mesa component is buried in a recess, which is then filled with a dielectric having substantially the same thermal expansion coefficient and the same dielectric constant as the insulating substrate. The surface of the mesa component and of the dielectric is in the plane of the planar part of the integrated circuit. Between the interconnecting microstrip lines on the planar face and the ground plane on the face of the substrate, the thickness and the dielectric constant of the material is constant.

Abstract: A field-effect transistor comprises an ancillary electrode in addition to the source, gate and drain electrodes. In this device, a semiconducting body bears source, gate and drain metallizations which define a main transistor. The metallization of the drain is separated into two parts which are separated by a channel on which is placed a second gate metallization defining a secondary transistor. The two parts of the drain are coupled by this secondary transistor, the channel of which is separated from the main channel. The secondary transistor can be used to control the gain of the main transistor or to modulate its amplitude signal or to mix two frequencies addressed on the two gates.

Abstract: A differential comparator, working with microwaves and using only one clock, is disclosed. This comparator has a differential amplifier and a divergence circuit in which are included two voltage level translators. The coupling between the amplifier and the divergence circuit is made at the gates of the load transistors of the divergence circuit. Two insulation transistors, working in either saturated mode or resistive mode, are used to provide the amplifier with an automatic control loop which stabilizes all the rest voltages. The clock signal, applied to two transistors which short circuit the two feedback transistors of the divergence circuit, controls the passage from the measuring phase to the divergence phase.

Abstract: A microwave transistor made with group III-V materials, such as GaAs and AlGaAs, is disclosed. This transistor essentially comprises a double heterojunction formed by a first layer of material with a big forbidden gap, n doped for example, a second non-doped layer with a narrow forbidden gap and a third p doped layer with a wide forbidden gap. Under the effect of the electrical field, there may be formed, simultaneously or not simultaneously, in the second layer, a two-dimensional electron gas at the interface with the first layer and a two-dimensional hole gas at the interface with the third layer. By bringing the thickness of the layers into play, the characteristics of the n and p channels can be made symmetrical.

Abstract: A digital/analog converter designed for very high frequencies is described. It has a first stage, which is a standard stage, in which several parallel-mounted controllable loads deliver currents in geometrical progression in a current/voltage converting transistor. Each controllable load has an input transistor, to the gate of which a bit is addressed as well as a diode and a saturable resistor. The second stage is a shifter formed by a transistor mounted as a follower source, in series with at least one diode and one pull-back transistor, the source of which is at a negative potential. The voltage at the drain of the converting transistor is applied to the gate of the shifter transistor, and the output voltage at the drain of the pull-back transistor is looped to the gate of the converting transistor.

Abstract: In an analog-digital converter working at microwave frequencies, the input signal is addressed in parallel to bit levels which are in cascade with one another. Each bit level has a transducer which converts the voltage into a current, and compares this current with a calibrated source. The resultant current is addressed to a logic circuit, the output of which delivers a bit. An intermediate output of the logic circuit constitutes a control signal which regulates the currents of the analog comparators of the less significant bit levels. The calibrated currents are in geometrical progression.

Abstract: Disclosed is a hyperfrequency device which includes a triple plate line in which at least two diodes exert their action at the same point on the suspended line. Instead of connecting the two diodes on both sides of the suspended line, they are mounted on the same side, this is possible by providing two subsidiary line sections orthogonal to the main line and in the same hyperfrequency plane. A diode is connected to the end of each subsidiary line at a point distant by .lambda.g/2 from the central point of the main line. The action of the two diodes is thus brought back to this point.

Abstract: A circuit for measuring the dynamic characteristics of encapsulating packages for high-speed integrated circuits includes at least two amplifiers integrated on a semiconductor substrate. These amplifiers have the same input and output impedances as those of the high-speed circuit to be encapsulated within the package. The amplifiers are located in widely spaced relation in order to ensure that there is no internal coupling. Depending on the measurements to be performed, the two amplifiers are mounted in parallel or in antiparallel relation. In order to measure the dynamic characteristics of a package, a measuring circuit is mounted within a package and a signal (V.sub.e) is addressed to an input connection of the package. The transmission and coupling coefficients are deduced from measurement of the signal (V.sub.S) collected on an output connection.

Abstract: An ultra-high frequency transistor is mounted in a hermetically sealed package in order to be made usable and in order to improve its performance characteristics to the optimum level. To diminish the noise factor of an ultra-high frequency transistor, the geometrical dimensions of the gate must be reduced. But the transistor changes its impedance and maximum frequency and can no longer be used in a package or at the external impedance of the circuit. It has to be pre-matched by having a choke mounted between its gate, its drain and the corresponding external connections. Each choke consists of a long metallic wire, forming a hairpin, soldered inside the package between the gate metallization and the internal end of its external connection or between the drain metallization and the internal end of its external connection. The invention can be applied to low-noise ultra-high frequency amplifiers.