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US 5,475,525 AGranted
Transverse electrical filter operating optically
AssigneeThomson-CSF
InventorsPierre Tournois, Daniel Dolfi, Jean-Pierre Huignard
Life of this patent
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Abstract
The invention relates to a programmable transverse filter required for the matched filtering of signals with very wide passband. The signals to be filtered modulate one or more optical carriers (F1) in a modulator (MOD). Each carrier is distributed over several channels by a distributor (DIV). A delay creation circuit (CR1 to CRn) is provided in each channel. These channels are next summed after having been correctly delayed and assigned a coefficient characteristic of the signal to be detected.
Claims24
Device for processing a signal comprising:
- an electro-optical modulator for receiving an optical wave and an electrical signal and retransmitting the optical wave modulated by the electrical signal, this retransmitted optical wave being linearly polarized;
- a beam splitter aligned along a path of the retransmitted optical wave for splitting the modulated optical wave into several elementary channels so that the modulated optical wave is travelling simultaneously along more than one of the several elementary channels relative to another one of the channels;
- a unit for creating time delays for a portion of the modulated optical wave along at least one of the channels relative to another one of the channels, said unit including means for creating said time delays for each of the elementary channels;
- a spatial light modulating means for modulating an amplitude of at least one of the elementary channels relative to an amplitude of another one of the elementary channels;
- a light intensity detector;
- and
- a beam concentrator for concentrating the portions of the modulated optical signals from the various channels and for focusing the optical signals from the various channels onto said light intensity detector.
4 more elements
A filter for filtering a time dependent signal, comprising:
- an electro-optic modulator for modulating a property of an optical beam with said time dependent signal when said time dependent signal is applied to said electro-optic modulator, said optical beam having a direction of propagation, a spatial extent in a transverse direction that is transverse to said direction of propagation, and being modulated along said direction of propagation by application of said time dependent signal to said electro-optic modulator;
- means for selectively delaying a first portion of said optical beam that is located in a different position along the transverse direction of said optical beam than a second portion of said optical beam, relative to the second portion of said optical beam;
- a spatial light intensity modulator, situated along the path of said optical beam, for independently modulating intensity of the first portion and the second portion;
- and
- means for detecting the combined intensity of both the delayed portion and the non-delayed portion of said optical beam.
2 more elements
Dependencies are inferred from the claim text.