US4872744A
Expired / Lapsed
US
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Single quantum well optical modulator
Assignee: Iconectiv LLC
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Filing: 1988-01-15
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Granted: 1989-10-10
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Expires: 2008-01-15
Abstract
Abstract High speed optoelectronic devices which are suitable for use in an optical integrated circuit design. The devices comprise a monolithic planar structure wherein exciton-resonant light propagates along a single mode waveguide containing a single quantum well as the absorbing media. Optical absorption is controlled by the bleaching effect induced by free carriers whose electrical conduction makes possible optical detection and monolithic high speed, gate-controlled transistor structures.
Inventors
- 👤 Joseph H. Abeles
- 👤 Alexander Kastalsky
- 👤 Robert F. Leheny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:04
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/015; G02F1/017; G02F1/01708; B; B82; B82Y; B82Y20/00; H; H10; H10D; H10D30/00; H10D30/40; H10D30/47; H10D30/471; H10D30/473; H10D30/4732; H10F; H10F30/00; H10F30/20; H10F30/21; H10F30/28; H10F30/283; H10F30/2843; H10F77/00; H10F77/10; H10F77/14; G02F1/0155; G02F1/0156
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
65 words
An optical modulator comprising a single quantum well (SQW) and a planar waveguide configuration coextensive with and overlapping said SQW for laterally confining light propagation through the modulator, said waveguide supporting light of a wavelength near or within the absorption wavelength band of excitons formed in said quantum well and monolithic field effect transistor means for altering the density of free carriers in said SQW.
Claim 2
Dependent Claim
65 words
An optical modulator comprising a single quantum well (SQW) and a planar waveguide configuration coextensive with and overlapping said SQW for laterally confining light propagation through the modulator, said waveguide supporting light of a wavelength near or within the absorption wavelength band of excitons formed in said quantum well and monolithic field effect transistor means for altering the density of free carriers in said SQW.
Claim 3
Dependent Claim
17 words
The optical modulator recited in claim 1 further including optical means for altering said free carrier density.
Claim 4
Dependent Claim
52 words
The optical modulator recited in claim 1 wherein said monolithic field effect transistor (FET) means includes a source, a gate and a drain electrode, said SQW lying under said gate electrode and acting as an FET channel, application of a voltage to said gate electrode controlling free carrier density in said SQW.
Claim 5
Dependent Claim
18 words
The optical modulator recited in claim 3 wherein said modulator comprises a plurality of semiconductor layers forming heterojunctions.
Claim 6
Dependent Claim
45 words
The optical modulator recited in claim 4 wherein said semiconductor layers comprise of sequence of Al x Ga 1-x As epilayers wherein x for each layer is selected such that the structure supports a single optical mode at or near the wavelength of exciton absorption.
Claim 7
Dependent Claim
18 words
The optical modulator recited in claim 4 wherein the layer in which said SQW is formed is GaAs.
Claim 8
Dependent Claim
34 words
The optical modulator recited in claim 4 wherein said waveguide is confined laterally by at least one semiconductor layer forming an elongated ridge extending above the surface of the remainder of said semiconductor layers.
Claim 9
Dependent Claim
14 words
The optical modulator recited in claim 3 wherein said gate is a Schottky gate.
Claim 10
Dependent Claim
95 words
An optical modulator comprising a plurality of semiconductor layers including a layer in which a single quantum well is formed in a specific region thereof, a planar optical waveguide for laterally confining light propagation through the modulator and which supports a single optical mode at or near the wavelength of exciton resonance, said single quantum well being coextensive with said waveguide, and monolithic field effect transistor means for altering the free carrier density in said single quantum well, said transistor means including a gate electrode for controlling the density of carriers in said quantum well.
Claim 11
Dependent Claim
95 words
An optical modulator comprising a plurality of semiconductor layers including a layer in which a single quantum well is formed in a specific region thereof, a planar optical waveguide for laterally confining light propagation through the modulator and which supports a single optical mode at or near the wavelength of exciton resonance, said single quantum well being coextensive with said waveguide, and monolithic field effect transistor means for altering the free carrier density in said single quantum well, said transistor means including a gate electrode for controlling the density of carriers in said quantum well.
Claim 12
Dependent Claim
62 words
The modulator recited in claim 9 wherein said waveguide is confined by an elongated ridge in a central region of said modulator and further comprising a gate electrode over said central region and a source and a drain electrode spaced from and on opposite sides of said gate electrode so as to enable electrical control of carrier density in said quantum well.
Claim 13
Dependent Claim
104 words
A bistable multivibrator circuit comprising a pair of field effect transistor optical modulators (FETOM's) as recited in claim 9 each having a source, a gate and a drain electrode said gate electrode associated with said quantum well for controlling the carrier density in said quantum well, means for applying a voltage to said FETOM's, said FETOM's coupled to each other and said voltage means such that a change in the electrical resistance between source and drain electrodes of one FETOM affects the gate voltage applied to the other FETOM so as to switch said other FETOM from a transparent state to an opaque state.
Claim 14
Dependent Claim
24 words
The circuit recited in claim 11 including optical means coupled to each FETOM for altering the resistance between source and drain of said FETOM.
Claim 15
Dependent Claim
89 words
An optically readable memory element comprising a device structure as recited in claim 9 wherein a concentration of electrons is normally present in said SQW and further comprising an n+ charge storage layer separated from said SQW by a p-type planar doped potential barrier and an ohmic contact to a single crystal semiconductor substrate on which active layers of said device are formed, and wherein with no bias voltage applied, the SQW is transparent at the exciton wavelength and upon application of a positive bias said SQW becomes opaque.
Claim 16
Dependent Claim
17 words
The memory element recited in claim 13 further including means for measuring the conductivity of said SQW.
Claim 17
Dependent Claim
21 words
The memory element recited in claim 13 further comprising a layer adjacent said SQW which provides a potential barrier to holes.
Claim 18
Dependent Claim
13 words
The memory element recited in claim 15 wherein said barrier layer is AlAs.
Claim 19
Dependent Claim
90 words
An optically switched charge storage device comprising a device structure as recited in claim 10 including a p + buried layer adjacent said SQW into which photogenerated holes in said SQW can escape, means for illuminating said SQW at the exciton wavelength and a means for applying a constant field to said p + layer such that said device switches from an opaque to a transparent state upon illumination and back again upon application of a negative pulse to said p+ layer relative to a gate electrode over said SQW.
Claim 20
Dependent Claim
19 words
The device recited in claim 17 including a conductor contacting said SQW and said p+layer to sweep out carriers.
Claim 21
Dependent Claim
14 words
The device recited in claim 17 wherein said gate electrode is a Schottky electrode.
References Cited (Backward Citations)
US3884732A
Cited
US4755857A
Cited
US4758868A
Cited
US4739385A
Cited
US4549788A
Cited
US4626075A
Cited
US4525687A
Cited
US4528464A
Cited
US4590502A
Cited
US4737003A
Cited
WO1985003171A1
Cited
JPS61289671A
Cited
US4705361A
Cited
EP0233011A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-09 | 1993-04-10 | 1993-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-09 | 1997-04-10 | 1997-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-09 | 2001-04-10 | 2001-10-10 | $7700.00 | Window Closed / Lapsed |