Societe Anonyme De Telecommunications

Other

Didier M Beaudet

Philippe Marie Allemandou

Michel G Berniere

Pierre Nicole

Gain of a photosensitive avalanche member, such as an avalanche photodiode, is stabilized so that a variation in gain of the photosensitive member in terms of temperature is compensated for by applying to the photosensitive member a bias voltage varying with temperature according to a predetermined relationship. The relationship depends on the variation with temperature in the voltage applied to terminals of at least one diode. The gain stabilizing device comprises a temperature-stabilized voltage source, a dc-dc voltage converter having an adjustable gain for applying a bias voltage to the photosensitive member, and at least one diode series-connected between the supply source and an input of the converter.

Device for stabilizing gain of a photosensitive avalanche member

The present invention relates to a device for regulating a laser diode, which comprises a generator of a pilot frequency signal modulated by a reference signal forming part of a composite signal to be emitted and a gain regulator of the composite signal. The regulation circuit comprises a photodiode whose output signal is demodulated by means of the pilot frequency signal, filtered then detected before being applied to the gain regulator.

Device for regulating a laser diode

A magnetostrictive mechanical filter comprising at least one rod of a magnetostrictive material forming a resonance element, a spool surrounding the rod, a field coil the windings of which are wound around the spool, and magnets creating a continuous magnetic field, arranged respectively at the ends of the rod, the rod being held radially in at least three points disposed regularly about the rod in the vicinity of the middle portion thereof, a rib being provided at each fixation point, said rib extending parallel to the generatrices of the rod and being formed on the inner peripheral surface of the spool and integrally molded with said spool.

Magnetostrictive mechanical filter

A pass-band electromechanical filter, comprising a mechanical unit vibrating in the longitudinal mode mounted between two electromechanical transducers, said unit comprising a plurality of half wave resonators mounted in series and coupling rods connecting the consecutive resonators, the resonators being distributed into two groups of which one comprises the resonators of odd rank and the other the resonators of even rank, the filter comprising moreover at least a bridging coupling rod connecting a resonator of rank k to a resonator of rank k+(2p+1) (p being a positive integer different from zero), said bridging coupling rod having its ends fixed at a certain distance from the end faces of the resonators, at least the bridging coupling rod on the one hand, or the coupling rod placed between the resonator of rank k and that of rank k+(2p+1) on the other hand, having a length which is respectively different from a three quarter wave or different from a quarter wave.

Electromechanical filters

A band-pass electromechanical filter, comprising an input electromechanical transducer, an output electromechanical transducer and a mechanical filter disposed therebetween, said filter having, alternately disposed, p resonators and (p - 1) coupling pins, resonating all in the longitudinal mode, wherein the coupling pins have identical diameters and lengths varied according to their respective position within said mechanical filter, said length being maximum in the middle of the filter and progressively decreasing towards the ends thereof.

Electromechanical band-pass filters

A method of measuring and, where necessary, modifying the natural vibration frequency of a metal bar, more especially a ferromagnetic bar, comprising freely suspending the bar in a constant magnetic field, subjecting the bar to action from outside to make it vibrate and detecting the resulting vibration frequency. There is also provided apparatus for carrying out the method, which comprises a vertical insulating cylinder, at the center of which the bar is kept freely suspended by a pneumatic device, means intended to make the bar vibrate, a solenoid which establishes a constant magnetic field and at the terminals of which the vibration frequency of the bar is detected, and a selective amplifier connected to the terminals of the solenoid.

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Saint Maur des Fosses, France

Didier M Beaudet