France Telecom

France Telecom Etablissement Autonome De Droit Public

Benoit Deveaud-Pledran

Jean-Michel Gerard

Philippe Gravey

Nikolaos Pelekanos

Christian Guillemot

A photorefractive device intended to be exposed to a marking radiation which is provided so as to create a grating of interference fringes in the device and to a reading radiation diffracted by the created grating. The device includes an electro-optical material having a quantum well structure (24) and formed in an intrinsic semi-conductor matrix (22, 24) and, on both sides of the material in the semi-conductor matrix, suitable means (28, 30) to trap, both parallel to the axis of the structure and perpendicular to this axis, free carriers generated by the marking radiation.

Photorefractive device with quantum wells

An optical operator designed to be subjected to write radiation for processing read radiation that it receives, the operator comprising an electro-optical material (Q2), first and second materials (Q1, Q3) distributed on either side of the electro-optical material (Q2), said first and second materials (Q1, Q3) being collection quantum wells. Quantum barrier forming materials (6, 8) are interposed between said two materials (Q1, Q3) and the electro-optical material (Q2), with one of the quantum barrier forming materials (6) constituting a filter such that charges of a certain sign photoexcited by the write radiation in a material (4, Q1) on one side of said filter pass through it in the absence of an external electric field to relax in the collection quantum well (Q3) situated on the other side of the filter (6), while charges of opposite sign are blocked by the filter (6) in the other collection well (Q1).

Quantum well heterostructure optical operator

Photoelectric detector presenting a multiple quantum well structure, each quantum well comprising a first barrier made from a first semiconductor material, a well made from a second semiconductor material, and a second barrier made from a third semiconductor material, each semiconductor material being defined by its chemical composition, and the electric conductibility in the detector being ensured by propagation, from the first barrier to the second barrier, of given charge carriers in a given electronic band, presenting an energy extremum in each of the said materials. In accordance with the invention, said semiconductor materials are at least partly doped with carriers, the chemical composition of the first and third semiconductor materials being such that the difference in energy, between the energy extremum of the said electronic band in the first semiconductor material and the energy extremum of the said electronic band in the third semiconductor material, is greater in absolute value than the maximum energy of the optical longitudinal phonons in the second semiconductor material making up the well. Application: infrared detectors, especially in the range 2.times.10.sup.13 -4.times.10.sup.13 Hz.

Quantum well photoelectric detector with improved detectivity

The amplifier according to the invention comprises a shallow, narrow well (P1) in which amplification takes place and a deep, wide well (P2) for collecting the carriers at the end of excitation, said well being emptied by the laser effect. Application to optical telecommunications.

Growing community of inventors

Lannion, France

Benoit Deveaud-Pledran