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US 6,646,774 B1Granted
Intra-bit polarization diversity modulation
OwnerAlan E. Willner, Zhongqi Pan +5inventors
InventorsAlan E. Willner, Zhongqi Pan, Yan Wang, Changyuan Yu, Ting Luo, Asaf B. Sahin, Qian Yu
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Abstract
Techniques and systems for mitigating polarization-related signal degradation or distortions in birefringent optical links based on intra-bit polarization diversity modulation.
Claims30
A system, comprising:
- an optical transmitter to produce at least one optical signal with optical pulses, each optical pulse having a first pulse portion in a first optical polarization and a second pulse portion immediately adjacent to said first pulse portion without overlap and in a second, orthogonal optical polarization;
- an optical transmission link, having optical birefringence with two orthogonal principal states of polarization, coupled to receive and transmit at least said one optical signal;
- a polarization element positioned to receive at least said one optical signal from said optical transmission link and to selectively transmit light in one of said two orthogonal principal states of polarization;
- and
- an optical detector positioned to receive said light from said polarization element.
2 more elements
A system, comprising:
- an optical transmitter to produce at least one optical signal with optical pulses, each optical pulse having a first pulse portion in a first optical polarization and a second pulse portion immediately adjacent to said first pulse portion without overlap and in a second, orthogonal optical polarization;
- an optical transmission link, having optical birefringence with two orthogonal principal states of polarization, coupled to receive and transmit at least said one optical signal;
- a polarization element positioned to receive at least said one optical signal from said optical transmission link and to selectively transmit light in one of said two orthogonal principal states of polarization;
- an optical detector positioned to receive said light from said polarization element;
- and
- a control unit coupled to adjust said polarization element to maintain transmission of light only in said one of said two orthogonal principal states of polarization when said two orthogonal principal states of polarization change, wherein said control unit receives a monitor signal indicative of an error in adjustment of said polarization element and adjusts said polarization element to reduce said error, and
- wherein said monitor signal includes information on a bit error rate in an output of said optical detector.
4 more elements
A method, comprising:
- causing optical pulses to transmit through a birefringent optical link, each optical pulse having a first pulse portion in a first optical polarization and a second pulse portion immediately adjacent to said first pulse portion without overlap and in a second, orthogonal optical polarization;
- and
- receiving transmitted light from the birefringent optical link to select a portion of the received transmitted light for optical detection, wherein the selected portion is polarized in one of two orthogonal principal states of polarization of the birefringent optical link.
A method, comprising:
- causing optical pulses to transmit through a birefringent optical link, each optical pulse having a first pulse portion in a first optical polarization and a second pulse portion immediately adjacent to said first pulse portion without overlap and in a second, orthogonal optical polarization;
- receiving transmitted light from the birefringent optical link to select a portion of the received transmitted light for optical detection, wherein the selected portion is polarized in one of two orthogonal principal states of polarization of the birefringent optical link;
- obtaining information on the two orthogonal principal states of polarization of the birefringent optical link during the detection;
- and
- dynamically adjusting a polarization-selecting element to maintaining the selected portion of the received transmitted light for optical detection in the selected principal state of polarization of the birefringent optical link,
- wherein the information is obtained a bit error rate in the optical detection.
3 more elements
A system, comprising:
- an optical modulator to modulate an intensity of input light to produce a train of optical pulses wherein light in each optical pulse is polarized only in a first optical polarization;
- and
- a polarization unit positioned to receive said train of optical pulses to cause a first part of each optical pulse to retain said first optical polarization and a second, immediately adjacent part of each optical pulse to be in a second optical polarization that is orthogonal to said first optical polarization.
A system, comprising:
- a first device to produce a train of optical pulses encoded with information of a data stream, where each optical pulse represents one data bit;
- a second device receiving said train of optical pulses to cause a first pulse portion of each pulse to be in a first optical polarization and a second pulse portion immediately adjacent to said first pulse portion without overlap of said each pulse to be in a second, orthogonal optical polarization;
- an optical communication link to transmit optical output from said second device;
- a polarization device coupled to receive optical output from said optical communication link and operable to select light in only one of said first and said second optical polarizations to produce a selected optical signal;
- and
- a receiver to receive said selected optical signal and to retrieve said data stream.
3 more elements
A method, comprising:
- generating optical pulses to present a data stream, wherein each optical pulse represents one data bit, and wherein a first pulse portion of each pulse and a second pulse portion immediately adjacent to said first pulse portion without overlap of said each pulse have orthogonal optical polarizations;
- transmitting said optical pulses over an optical link to a receiver;
- and
- selecting light in only one of said orthogonal optical polarizations for detection at the receiver to retrieve said dat stream.
1 more element
Dependencies are inferred from the claim text.