Free-space optical communication system employing wavelength conversion
First Claim
1. A method of communicating optical signals over a free-space link, comprising the steps of:
- receiving a first optical signal having a fiber interface fundamental wavelength from a first single mode optical fiber;
converting the fiber interface fundamental wavelength of the first optical signal to a free-space fundamental wavelength with a transmit wavelength transformer;
directing the first optical signal having the free-space fundamental wavelength over the free-space link;
receiving a second optical signal having the free-space fundamental wavelength from the free-space link;
converting the free-space fundamental wavelength of the second optical signal to a fiber interface fundamental wavelength with a receive wavelength transformer; and
directing the second optical signal having the fiber interface fundamental wavelength into a second single mode optical fiber.
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Abstract
Free-space optical transceivers employ wavelength conversion from a fiber interface wavelength λfiber to a free-space transform wavelength λfs and back again to overcome a broad range of environmental impacts to the free-space optical signal, such as fog. The wavelength conversions may be performed all-optically without the need for electro-optical conversion, or the wavelength conversions may be performed using electro-optical conversion. The performance of the chosen value for the free-space transform wavelength λfs may be monitored and a feedback control system used to dynamically adjust the value for λfs until the optimum value for the given atmospheric conditions is achieved. Cooperating transceivers can be informed of a newly selected value for λfs via a direct, out-of-band control communications channel, or cooperating transceivers can determine the appropriate wavelength transform amount to be applied by an adaptive wavelength selection determination.
140 Citations
50 Claims
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1. A method of communicating optical signals over a free-space link, comprising the steps of:
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receiving a first optical signal having a fiber interface fundamental wavelength from a first single mode optical fiber;
converting the fiber interface fundamental wavelength of the first optical signal to a free-space fundamental wavelength with a transmit wavelength transformer;
directing the first optical signal having the free-space fundamental wavelength over the free-space link;
receiving a second optical signal having the free-space fundamental wavelength from the free-space link;
converting the free-space fundamental wavelength of the second optical signal to a fiber interface fundamental wavelength with a receive wavelength transformer; and
directing the second optical signal having the fiber interface fundamental wavelength into a second single mode optical fiber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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12. An apparatus for communicating optical signals over a free-space link, comprising:
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means for receiving a first optical signal having a fiber interface fundamental wavelength from a first single mode optical fiber;
a transmit wavelength transformer configured to convert the fiber interface fundamental wavelength of the first optical signal to a free-space fundamental wavelength;
a transmitting element configured to direct the first optical signal having the free-space fundamental wavelength over the free-space link;
a receiving element configured to receive a second optical signal having the free-space fundamental wavelength from the free-space link;
a receive wavelength transformer configured to convert the free-space fundamental wavelength of the second optical signal to a fiber interface fundamental wavelength; and
means for directing the second optical signal having the fiber interface fundamental wavelength into a second single mode optical fiber.
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22. A method of communicating optical signals over a free-space link, comprising the steps of:
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receiving a first optical signal having a fiber interface fundamental wavelength from a first single mode optical fiber;
amplifying the first optical signal with a multi-wavelength optical amplifier connected in-line with the first single mode optical fiber;
attenuating the first optical signal with a variable optical attenuator that is optically coupled to the multi-wavelength optical amplifier;
converting the fiber interface fundamental wavelength of the first optical signal to a free-space fundamental wavelength with a transmit wavelength transformer; and
directing the first optical signal having the free-space fundamental wavelength over the free-space link. - View Dependent Claims (23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42)
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29. An apparatus for communicating optical signals over a free-space link, comprising:
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means for receiving a first optical signal having a fiber interface fundamental wavelength from a first single mode optical fiber;
a multi-wavelength optical amplifier connected in-line with the first single mode optical fiber for amplifying the first optical signal;
a variable optical attenuator that is optically coupled to the multi-wavelength optical amplifier for attenuating the first optical signal;
a transmit wavelength transformer configured to convert the fiber interface fundamental wavelength of the first optical signal to a free-space fundamental wavelength; and
one or more transmitting elements configured to direct the first optical signal having the free-space fundamental wavelength over the free-space link.
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35. A method of communicating optical signals over a free-space link, comprising the steps of:
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receiving a first optical signal having the free-space fundamental wavelength from the free-space link;
converting the free-space fundamental wavelength of the first optical signal to a fiber interface fundamental wavelength with a receive wavelength transformer;
amplifying the first optical signal with a multi-wavelength optical amplifier optically coupled to the receive wavelength transformer;
attenuating the first optical signal with a variable optical attenuator that is optically coupled to the multi-wavelength optical amplifier; and
directing the first optical signal having the fiber interface fundamental wavelength into a first single mode optical fiber.
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43. An apparatus for communicating optical signals over a free-space link, comprising:
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a receiving element configured to receive a first optical signal having the free-space fundamental wavelength from the free-space link;
a receive wavelength transformer configured to convert the free-space fundamental wavelength of the first optical signal to a fiber interface fundamental wavelength;
a multi-wavelength optical amplifier optically coupled to the receive wavelength transformer for amplifying the first optical signal;
a variable optical attenuator that is optically coupled to the multi-wavelength optical amplifier for attenuating the first optical signal; and
means for directing the first optical signal having the fiber interface fundamental wavelength into a first single mode optical fiber. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50)
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Specification