Optical: systems and elements – Optical modulator – Light wave temporal modulation
Patent
1994-08-29
1996-12-24
Ben, Loha
Optical: systems and elements
Optical modulator
Light wave temporal modulation
359285, 359298, 359559, 359308, 364822, 364827, 342368, G02F 111
Patent
active
055878296
ABSTRACT:
A signal filter, and method of signal filtering, in which an optical signal s spatially dispersed according to frequency, and undesired frequencies blocked out. In an embodiment, a Bragg cell receives a (typically microwave) signal, and transduces it to an acoustic signal. A light source, e.g. a laser diode, directs light through the acoustic signal in a known manner so as to produce an optical output which is spatially dispersed according to frequency. A programmable spatial light modulator blocks out unwanted frequency components. Upon removal of the optical carrier, e.g. by heterodyning the spatial light modulator's output with a reference signal from the light source, the components can be recombined into a resultant filtered signal. The invention can be used as a repeater, a military electronic countermeasure, in environments which have large amounts of electromagnetic clutter but in which one does not want the clutter repeated. The spatial light modulator can be programmed to pass only frequency components in which one is interested, thus blocking the clutter from the repeated signal.
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Alexander Edward M.
Spezio Anthony E.
Ben Loha
McDonnell Thomas E.
Miles Edward
The United States of America as represented by the Secretary of
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