EP0249645A1
Expired / Lapsed
EP
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Optoelectronic voltage-controlled modulator
Assignee: International Business Machines Corp
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Filing: 1986-06-18
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Granted: —
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Expires: 2006-06-18
Abstract
Abstract The light beam modulator (10) consists of an optical absorber (13) and a buried reflector (12) underneath, both being formed on a substrate (11) which may consist of GaAs. Control voltages (V c ), that determine the degree of absorbtion in the absorber (13), are applied to contacts (15, 16) at the top and bottom of the modulator structure. The patterned top contact defines a window (18) through which the light beam (17) enters and, after modulation, leaves the device. The beam passes the absorber (13) twice, i.e., before and after its reflection at the reflector (12). The degree of intensity variation, or modulation, depends on the applied control voltage (V c ). The modulator is external to the source of the light beam to be modulated, and it is reflective in that incoming and reflected light beams pass through the same window.
Inventors
- 👤 Heinz Peter Meier
- 👤 Christoph Stephan Harder
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 21:43
CPC Classifications
B; B82; B82Y; B82Y20/00; G; G02; G02F; G02F1/00; G02F1/01; G02F1/015; G02F1/017; G02F1/0155; G02F1/0157; G02F2201/00; G02F2201/34; G02F2201/346; G02F2203/00; G02F2203/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
88 words
Optoelectronic voltage-controlled modulator for the external modulation of a light beam, comprising - a semiconductor substrate (31), - a reflector (33) consisting of a layered semiconductor structure epitaxially grown on one surface of said substrate, and - an absorber (34) consisting of a semiconductor structure epitaxially grown on said reflector structure such that the intensity of a light beam (L), passing through the absorber before and after being reflected, can be modulated by means of electric control signals applied to contacts (37, 39) connecting to said modulator structure.
Claim 2
Dependent Claim
88 words
Optoelectronic voltage-controlled modulator for the external modulation of a light beam, comprising - a semiconductor substrate (31), - a reflector (33) consisting of a layered semiconductor structure epitaxially grown on one surface of said substrate, and - an absorber (34) consisting of a semiconductor structure epitaxially grown on said reflector structure such that the intensity of a light beam (L), passing through the absorber before and after being reflected, can be modulated by means of electric control signals applied to contacts (37, 39) connecting to said modulator structure.
Claim 3
Dependent Claim
30 words
A modulator as claimed in claim 1, wherein said reflector (33) consists of a superlattice structure comprising a plurality of pairs of alternate layers (33a, 33b) of different semiconductor compounds.
Claim 4
Dependent Claim
30 words
A modulator as claimed in claim 2, wherein the optical thicknesses of said alternate layers (33a, 33b) equal a quarter wavelength of the light beam that is to be modulated.
Claim 5
Dependent Claim
20 words
A modulator as claimed in claim 3, wherein the wavelength of the light beam is between 0.8 and 0.9 µ.
Claim 6
Dependent Claim
19 words
A modulator as claimed in claim 2, wherein said alternate layers (33a, 33b) consists of AlAs and GaAlAs, respectively.
Claim 7
Dependent Claim
24 words
A modulator as claimed in claim 1, wherein said absorber (34) consists of a plurality of pairs of alternate layers of different semiconductor compounds.
Claim 8
Dependent Claim
35 words
A modulator as claimed in claim 6, wherein said pairs of layers comprise a first layer (34a) forming a quantum well, and a second layer (34b) forming a separating barrier between subsequent quantum well layers.
Claim 9
Dependent Claim
24 words
A modulator as claimed in claim 7, wherein said quantum well layers (34a) and said barrier layers (34b) consists of GaAs and GaAlAs, respectively.
Claim 10
Dependent Claim
37 words
A modulator as claimed in claim 1, wherein said substrate (31) consists of semi-insulating GaAs and is covered with a doped GaAs buffer layer (32) that provides the surface on which said reflector structure (33) is grown.
Claim 11
Dependent Claim
40 words
A modulator as claimed in claim 1, wherein one of said contacts (37) is arranged on top of the absorber structure (34) and ring-shaped to define a window for the passage of the incoming and the reflected light beams (L).
Claim 12
Dependent Claim
32 words
A modulator as claimed in claim 1, wherein one of said contacts (39) is arranged on said semiconductor surface besides the stack of layers forming the reflector (33) and absorber (34) structures.
Claim 13
Dependent Claim
36 words
A modulator as claimed in claim 1, wherein one of said contacts (39) is arranged at the surface of said semiconductor substrate (31) that is opposite said substrate surface on which the reflector (33) is grown.
Claim 14
Dependent Claim
36 words
A modulator as claimed in claim 1, wherein an antireflection coating (38) of a thickness that equals a quarter wavelength of the light beam to be modulated is deposited on top of said absorber structure (34).
References Cited (Backward Citations)
FR1603131A
Cited
WO1984003397A1
Cited
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