Electromagnetic wave modulator equipped with coupled quantal wells, and application to an electromagnetic wave detector
AssigneeThomson-CSF
InventorsNakita Vodjdani, Claude Weisbuch, Borge Vinter, Julien Nagle, Michel Papuchon, Jean-Paul Pocholle, Dominique Delacourt
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Abstract
A semi-conducting structure delimits two quantal wells (CP1, CP2) connected across a barrier layer (CB). The application of an electric field to the structure makes possible the transfer of electrons from one of the wells to the other. The electron-hole pairs are created by a wave-pump, or by the doping of one of the wells. This makes possible, in particular, a dual control by means of the wave-pump and the electric field, thus creating an "AND"-function modulator.
Claims17
An electromagnetic wave modulator, comprising:
- a semi-conducting structure containing a first alternating arrangement of layers making up a first quantal well;
- means for populating the first discrete energy level of the first quantal well with electrons;
- and
- means for controlling the absorption of a wave to be modulated by the quantal well,
- wherein said semi-conducting structure incorporates another alternating arrangement of layers in proximity to the first set of alternating layers and delimiting a second quantal well, which is coupled to the first quantal well across a barrier layer, and wherein said means of control contain means for applying upon command to said structure an electric field perpendicular to said barrier, thereby permitting an increase in the life-span of the electron-hole pairs thus created, and wherein the compositions of the quantal wells are such that the first well allows a single discrete level of energy, while the second well allows two levels of energy whose differential corresponds to the frequency to be modulated multiplied by Planck's constant.
Modulator according to any of claims 12 and 4-12, wherein it operates in the near-infrared range.
Modulator according to any of the preceding claims, wherein it receives a wave to be modulated which is guided along one or two dimensions.
Modulator according to any of the preceding claims, wherein the pattern of two quantal wells is repeated several times.
Electromagnetic wave detector using the modulator according to any of the preceding claims, wherein it incorporates ohmic contacts on the outer surfaces of the device on either side of the quantal wells, as well as a current detector connected to these ohmic contacts.
Dependencies are inferred from the claim text.