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| Optical phase filter using liquid crystal |
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| Twisted nematic liquid crystal display device |
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| Complex spatial modulator |
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| Active phase and amplitude modulator |
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| Projection display apparatus |
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| Spatial light modulator with full complex light modulation capability |
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Optoelectronic multibit beamsteering switching apparatus
| Details |
Inventors: Newberg, Irwin L.; Lind, Richard C.; Tangonan, Gregory L.; Yen, Huan W.; Ng, Willie W.; Lee, Jar J.; Walston, Andrew A.; Wechsberg, Michael;
Assignee: Hughes Aircraft Company (Los Angeles, CA)
Primary Examiner: Goldstein; Herbert
Assistant Examiner: Negash; Kinfe-Michael
Attorney, Agent or Firm: Alkov; L. A., Denson-Low; W. K.
Optoelectronic switching apparatus employing optoelectronic switching devices interconnected by optical media having different delay lengths and an multiport optical coupler. The optoelectronic switching apparatus provides for a multibit true-time-delay beamsteerer for beamsteering phased array antennas. The present invention combines two types of optoelectronic devices, lasers and photodiode switches, using an interconnected passive optical network comprising the optical fibers and the optical coupler. The switches, and input and output signal networks coupled to the respective switches, are controlled using a control signal generator. Using this scheme, any input can be independently selected and a signal can be routed to any output. Furthermore, the product of the total number of different interconnect paths (N.times.M) is provided which provides a greater number of delay lengths than is provided by using only one type of switch (i.e. laser (N) or photodiode (M)) alone. The present invention also provides for improved insertion loss while increasing the number of delay paths. |
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DETAILED DESCRIPTION In order to meet the above objectives, present invention comprises optoelectronic switching apparatus that is adapted for use in multibit beamsteering applications.
The optoelectronic switching apparatus is comprised of an input signal network, a laser transmitter section, a light receiver section, an interconnected passive optical network comprising an optical coupler and a plurality of input and output optical coupling means that interconnects the transmitter section and the receiver section, an output signal network, and a control signal generator.
The input signal network is adapted to process or distribute an applied input signal, such as a radio frequency (RF) signal, for example, such that the input signal is coupled from the signal input to signal inputs of the transmitter section.
The transmitter section is comprised of a plurality of laser switches that each include a laser having an RF signal input coupled to a selected signal output of the input signal network, and a control switch coupled to the laser that has a control signal input that is coupled to the control signal generator.
The control switch is also coupled between a first bias voltage source and the laser.
The RF input signal input to the switching apparatus is processed by the input signal network and is distributed from the respective signal outputs thereof to respective RF signal inputs of the plurality of laser switches.
The light receiver section comprises a plurality of photodiode switches that are generally arranged in a manner similar to the laser switches.
Each photodiode switch comprises a photodiode detector having a signal input and a signal output, and a control switch having a control signal input coupled between the control signal generator and the photodiode detector.
The control switch is also coupled between a second bias voltage source and the photodiode detector.
Switch control signals are coupled between the control signal generator and the respective control switches of the light receiver section
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