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US 5,432,634 AGranted
Electromagnetic wave modulator with quantum well structure
AssigneeThomson-CSF
InventorsEmmanuel Dupont, Dominique Delacourt, Michel Papuchon
Life of this patent
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Abstract
The invention pertains to an electromagnetic wave modulator comprising a quantum well semiconductor structure having two adjacent wells, the coupling of which is modified under the effect of an electrical field by the use of the phenomenon of anti-crossing of resonating levels. With this type of modulator, it is possible to attain 20% of modulation (as in the prior art) but with heightened sensitivity to the electrical field and a very short response time.
Claims10
An electromagnetic wave modulator, comprising;
- a doped semiconductor structure having a stack of layers constituted by semiconductor materials enabling the creation of potential wells;
- means for placing a voltage across the stack of layers of the semiconductor structure;
- wherein the stack of layers of the doped semiconductor structure form
- a first potential well P.sub.1 possessing at least two states, one of said two states has a discrete energy level e.sub.0 populated with electrons and the other one of said two states has a discrete energy level e.sub.1 such that e.sub.1 is greater than e.sub.0 ;
- a second potential well P.sub.2 possessing at least one state with a discrete energy level e.sub.2 such that e.sub.2 and e.sub.1 are equal, wherein the level at energy e.sub.2 is the fundamental level of the well P.sub.2 ;
- the wells P.sub.1 and P.sub.2 being separated by a distance d such that the discrete energy levels at e.sub.1 and e.sub.2 are in resonance, the resonance creating two states at energies e.sub.L and e.sub.A, with e.sub.L and e.sub.A greater than e.sub.0,
- wherein modulation of an incident electromagnetic wave results from the variations of absorption related to the transitions between, firstly, the levels at energies e.sub.0 and e.sub.L and, secondly, the levels at energies e.sub.0 and e.sub.A, as a function of the voltage across the stack of layers.
4 more elements
An electromagnetic wave modulator, comprising
- a doped semiconductor structure having a stack of layers constituted by semiconductor materials enabling the creation of potential wells;
- means for placing a voltage across the stack of layers of the semiconductor structure;
- wherein the stack of layers of the doped semiconductor structure form a first potential well P.sub.1 possessing at least two states, one of said two states has a discrete energy level e.sub.0 populated with electrons and the other one of said two states has a discrete energy level e.sub.1 such that e.sub.1 is greater than e.sub.0 ;
- a second potential well P.sub.2 possessing at least one state with a discrete energy level e.sub.2 such that e.sub.2 and e.sub.1 are equal and in resonance with one another which gives rise to splitting of the states with energy levels e.sub.2 and e.sub.1 into a bonding and an antibonding state, wherein an electric field applied across the stack of layers favors transitions into either the antibonding or bonding state;
- the wells P.sub.1 and P.sub.2 being separated by a distance d such that the discrete energy levels at e.sub.1 and e.sub.2 are in resonance, the resonance creating two states at energies e.sub.L and e.sub.A, with e.sub.L and e.sub.A greater than e.sub.0,
- wherein modulation of an incident electromagnetic wave results from the variations of absorption related to the transitions between, firstly, the levels at energies e.sub.0 and e.sub.L and, secondly, the levels at energies e.sub.0 and e.sub.A, as a function of the voltage across the stack of layers.
3 more elements
Dependencies are inferred from the claim text.