Thomson-csf

Pierre Hirtz

Baudouin De Cremoux

Pierre Poulain

Claude Puech

Pierre Leclerc

Marie A Di Forte

A phototransistor which is capable of operating alternately in the emission mode and in the reception mode can be coupled under favorable conditions to an optical fiber in a telecommunications system. An active layer constitutes the base of the transistor and forms a heterojunction with two layers of opposite conductivity type which constitute the emitter and collector of the transistor. The base contact is formed by a heavily doped region of the same conductivity type as the active layer and defines the useful zone of photon coupling between the optoelectronic component and the entrance face or exit face of the optical fiber.

Light emitting and receiving transistor for operation in alternate

A phototransistor in planar technology for optical fiber communications permitting an easy formation of the contact connection of the transistor base located within the intermediate layer of an npn stack as well as accurate localization of the pn junction. To this end, the upper semiconductor layer initially receives a first diffusion of doping impurity in a first region which penetrates into the lower layer to a slight extent and forms the base region. An impurity of opposite type is then implanted in a second region which is located within the first and forms the emitter region whilst the substrate constitutes the collector. The base and emitter connections are formed on the free face whilst the collector is connected on the substrate side.

Heterojunction phototransistor constructed in planar technology

The invention relates to a semiconductor laser with a distributed reflector comprising a semiconductor junction, one of whose semi-transparent mirrors is a split face of the semiconductor in which is integrated a light emitting junction with epitaxial layers. The active layer of this junction is coupled to a waveguide integrated in a dielectric medium, on one face of which is engraved a grating forming a distributed reflector playing the part of the second mirror. The reflector, when functioning according the second order of counter coupling emits a diffracted wave normal to the waveguide which can easily be coupled to an optical fiber.

Laser with distributed reflector

The invention relates to a diode which transmits and receives light-rays in the same wavelength. A first transmitting layer is separated from the second receiving layer, and has the opposite type of conductivity to that of the first, this layer having a large forbidden bandwidth, the functions of transmission and reception being thus separated from one another. The invention is applicable to a system of telecommunication by optical fibers.

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Paris, France

Pierre Hirtz