Transmit-receive fiber-optic manifold for phase array antennas

• US 5,751,242 A
• Filed: 09/30/1995
• Issued: 05/12/1998
• Est. Priority Date: 09/30/1995
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Goutzoulis, Anastasios P., Zomp, John M.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/521,202
• Time in Patent Office: 955 Days
• Field of Search: 342/372, 342/375, 342/81, 342/157, 342/158
• US Class Current: 342/158
• CPC Class Codes: G01S 2013/0245 Radar with phased array antenna
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems
• CPC Class Codes: G02B 6/04 formed by bundles of fibres G02B6/24 takes precedence
• CPC Class Codes: G02B 6/4249 comprising arrays of active devices and fibres

Abstract

A signal manifold having a source signal converter coupled to an RF source for converting a source electronic signal from the RF source into an optical signal. The manifold has an optical coupler, having multiple optical fibers, coupled to the first signal converter; and a sink signal converter coupled to the optical coupler. The sink signal converter converts the optical signal from the coupler into a sink electronic signal and conveys that electronic signal to an RF sink.

The manifold can be a transmit manifold, or a receive manifold. In addition, a transmit manifold and a receive manifold can be combined to provide a bi-directional signal manifold. The invention herein also provides low-loss asymmetric fiber-optic combiner which includes multiple optical fibers, each fiber having cladding removed from the respective fiber end, exposing the fiber core. The cores are joined together in a predefined configuration and each are optically coupled to a plenum optical fiber. A method for fabricating the low-loss asymmetric fiber-optic combiner also is provided and includes the steps of etching a portion of multiple optical fibers, and removing the cladding from the optical core, producing multiple exposed optical core segments. An optical core bundle with a bundle end is formed by collaterally joining each of the multiple exposed optical core segments with the others. A planar bundle end is formed from the optical core bundle end by polishing, and rendering coplanar, the bundle end. The bundle end is coupled to a plenum optical fiber.

Claims

1. A transmit signal manifold, comprising:

(a) a source signal converter;

(b) a sink signal converter;

(c) said source signal converter being coupled to an S-band RF transmitter source for converting an S-band source electronic signal from said S-band RF transmitter source into an optical signal;

(d) an optical coupler operably coupled to said source signal converter, said optical coupler having a plurality of optical fibers;

(e) said source signal converter including an optical source and a first fiber-optic divider coupled between said optical source and said optical coupler, said optical source producing said optical signal responsive to said S-band source electronic signal, said divider selectively conveying said optical signal to said plurality of optical fibers;

(f) said source signal converter additionally including an RF divider coupled to said S-band RF transmitter source, said RF divider having a first predetermined RF divider ratio;

(g) said optical source including a laser for producing an optical carrier signal with a preselected carrier wavelength, and a plurality of Mach-Zehnder electro-optical modulators for modulating said S-band source electronic signal onto said carrier signal providing said optical signal thereby;

(h) said optical coupler including a plurality fiber-optic dividers, each of said plurality of fiber-optic dividers having an input and a plurality of outputs each of said inputs being connected to a respective one of said plurality of Mach-Zehnder electro-optical modulators, each of said outputs being coupled to said sink signal converter;

(i) said sink signal converter being operably coupled to said optical coupler for converting said optical signal into a sink electronic signal, said sink signal converter being coupled to a phased array antenna sink for conveying said sink electronic signal thereto said sink signal converter including an optical detector coupled to said optical coupler, said optical detector producing said sink signal electronic signal responsive to said optical signal.

2. A transmit-receive signal manifold, comprising:

(a) a source transmit signal converter coupled to an RF transmitter, and receiving a source transmit electronic signal therefrom, said source transmit signal converter converting said transmit electronic signal into a transmit optical signal;

(b) an optical transmit coupler operably coupled to said source transmit signal converter, said optical transmit coupler having a first plurality of optical fibers for conveying said transmit optical signal therethrough;

(c) a sink transmit signal converter operably coupled to said optical transmit coupler and receiving said transmit optical signal therefrom, said sink transmit signal converter being coupled to a phased array antenna, said sink transmit signal converter converting said transmit optical signal into a sink transmit electronic signal and conveying said electronic signal to said antenna;

(d) a source receive signal converter coupled to said phased array antenna and receiving a receive signal therefrom, said converter converting said source receive electronic signal to a receive optical signal;

(e) a duplexer interposed between said sink transmit signal converter and said source receive signal converter and said phased array antenna for selectively coupling one of said sink transmit signal converter and said source receive signal converter to said phased array antenna;

(f) an optical receive coupler, including a low-loss asymmetric fiber-optic combiner, operably coupled to said source receive signal converter, said optical receive coupler having a second plurality of optical fibers for conveying said receive optical signal therethrough; and

(g) a sink receive signal converter coupled to said optical receive coupler and coupled to an RF receiver for converting said receive optical signal into said sink receive electronic signal and conveying said electronic signal to said RF receiver.

3. A transmit-receive signal manifold, comprising:

(a) a source transmit signal converter coupled to a UHF-band RF transmitter, and receiving a UHF-band source transmit electronic signal therefrom, said source transmit signal converter converting said transmit electronic signal into a transmit optical signal, said source transmit signal converter including a first optical source and a first fiber-optic divider coupled between said first optical source and an optical transmit coupler, said first optical source producing said transmit optical signal responsive to said source transmit electronic signal, said first optical source including a laser diode producing said transmit optical signal with a preselected wavelength, and a laser diode driver for receiving said source transmit electronic signal and energizing said laser diode responsive thereto;

(b) an optical transmit coupler operably coupled to said source transmit signal converter, said optical transmit coupler having a first plurality of optical fibers for conveying said transmit optical signal therethrough, said optical transmit coupler including a first plurality of fiber-optic dividers operably connected in series to said first fiber-optic divider;

(c) a sink transmit signal converter operably coupled to said optical transmit coupler and receiving said transmit optical signal therefrom, said sink transmit signal converter being coupled to a phased array antenna, said sink transmit signal converter converting said transmit optical signal into a sink transmit electronic signal and conveying said electronic signal to said antenna, said sink transmit signal converter including a transmit optical detector coupled to said optical transmit coupler, said transmit optical detector producing said sink transmit electronic signal responsive to said transmit optical signal;

(d) a source receive signal converter coupled to said phased array antenna and receiving a receive signal therefrom, said converter converting said source receive electronic signal to a receive optical signal, said source receive signal converter including a plurality of second optical sources for converting said source receive electronic signal into said receive optical signal, said plurality of second optical sources being selectively coupled to said plurality of optical fibers for conveying said receive optical signal therethrough;

(e) a duplexer interposed between said sink transmit signal converter and said source receive signal converter and said phased array antenna for selectively coupling one of said sink transmit signal converter and said source receive signal converter to said phased array antenna;

(f) an optical receive coupler, including a low-loss asymmetric fiber-optic combiner, operably coupled to said source receive signal converter, said optical receive coupler having a second plurality of optical fibers for conveying said receive optical signal therethrough; and

(g) a sink receive signal converter coupled to said optical receive coupler and coupled to a UHF-band RF receiver for converting said receive optical signal into said sink receive electronic signal and conveying said electronic signal to said RF receiver, said sink receive signal converter including an optical combiner coupled to said plurality of optical fibers for receiving said receive optical signal and a second optical detector for producing said sink receive electronic signal responsive to said receive optical signal; and

wherein

(h) each of said plurality of optical sources includes a laser diode producing a portion of said optical receive signal with a preselected wavelength, and a laser diode driver connected to said laser diode for energizing said laser diode responsive to said source receive electronic signal; and

wherein

(i) said optical coupler includes at least one second combiner for combining each of said portions into said receive optical signal.

4. A transmit-receive signal manifold, comprising:

(a) a source transmit signal converter coupled to an S-band RF transmitter, and receiving an S-band source transmit electronic signal therefrom, said source transmit signal converter converting said transmit electronic signal into a transmit optical signal, said source transmit signal converter including an RF divider coupled to said RF source and receiving a source transmit electronic signal therefrom, said converter converting said transmit electronic signal into a transmit optical signal by a first optical source, said first optical source including a laser for producing an optical carrier signal with a preselected carrier wavelength, said first optical source further including a plurality of Mach-Zehnder electro-optical modulators for modulating said source transmit electronic signal onto said carrier signal providing said transmit optical signal thereby, said RF divider having a first predefined RF divider ratio;

(b) an optical transmit coupler operably coupled to said source transmit signal converter, said optical transmit coupler having a first plurality of optical fibers for conveying said transmit optical signal therethrough, said optical transmit coupler including a plurality of fiber-optic dividers, each of said dividers having an input and a plurality of outputs, each of said inputs being connected to respective ones of said plurality of Mach-Zehnder electro-optic modulators, each of said outputs being coupled to said sink transmit signal converter, a first stage of said fiber-optic dividers having a predefined fiber-optic divider ratio corresponding to the number of first divider output fibers, each of the remaining fiber-optic dividers having a second predefined divider ratio;

(c) a sink transmit signal converter operably coupled to said optical transmit coupler and receiving said transmit optical signal therefrom, said sink transmit signal converter being coupled to a phased array antenna, said sink transmit signal converter converting said transmit optical signal into a sink transmit electronic signal and conveying said electronic signal to said antenna;

(d) a source receive signal converter coupled to said phased array antenna and receiving a receive signal therefrom, said converter converting said source receive electronic signal to a receive optical signal;

(e) a duplexer interposed between said sink transmit signal converter and said source receive signal converter and said phased array antenna for selectively coupling one of said sink transmit signal converter and said source receive signal converter to said phased array antenna;

(f) an optical receive coupler, including a low-loss asymmetric fiber-optic combiner, operably coupled to said source receive signal converter, said optical receive coupler having a second plurality of optical fibers for conveying said receive optical signal therethrough; and

(g) a sink receive signal converter coupled to said optical receive coupler and coupled to an S-band RF receiver for converting said receive optical signal into said sink receive electronic signal and conveying said electronic signal to said RF receiver.

5. The manifold of claim 4 wherein said laser produces said carrier signal at a preselected wavelength of about 1300 nm.

6. The manifold of claim 4 wherein said first predefined divider ratio is 1:

8 and said second predefined divider ratio is 1;

32 and each of said plurality of combiners has a predefined combiner ratio of 16;

1.