Linearization of a broadband analog optical link using two wavelengths
First Claim
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1. A method of linearizing a signal transmitted over a communication link, comprising the steps of:
- supplying a first signal having a first wavelength;
supplying a second signal having a second wavelength;
modulating said first and second signals differentially with respect to each other to obtain a first modulated signal and a second modulated signal, respectively;
detecting said first modulated signal to obtain a first detected signal;
detecting said second modulated signal to obtain a second detected signal; and
performing a linear operation on said first detected signal and said second detected signal to generate a received signal having substantially zero second-order modulator-induced distortion and zero third-order modulator-induced distortion.
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Abstract
A modulator driven by an externally applied RF signal intensity modulates carrier signals at different wavelengths. The modulator bias voltage and the ratio of the optical powers of the carrier signals are selected to minimize second and third order distortion. The modulated signals are separately detected and the resulting electrical signals are combined to yield a linearized representation of the RF signal. An electro-optic device capable of wavelength multiplexing and demultiplexing can independently and jointly control the bias voltages for the transfer functions of the two carrier signals.
107 Citations
13 Claims
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1. A method of linearizing a signal transmitted over a communication link, comprising the steps of:
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supplying a first signal having a first wavelength;
supplying a second signal having a second wavelength;
modulating said first and second signals differentially with respect to each other to obtain a first modulated signal and a second modulated signal, respectively;
detecting said first modulated signal to obtain a first detected signal;
detecting said second modulated signal to obtain a second detected signal; and
performing a linear operation on said first detected signal and said second detected signal to generate a received signal having substantially zero second-order modulator-induced distortion and zero third-order modulator-induced distortion. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of linearizing a received radio-frequency signal comprising the steps of:
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supplying a first signal having a first wavelength;
supplying a second signal having a second wavelength;
modulating said first and second signals differentially with respect to each other in response to said received radio-frequency signal to obtain a first modulated signal and a second modulated signal;
detecting the first modulated signal to obtain a first detected signal;
detecting the second modulated signal to obtain a second detected signal; and
performing a linear operation on said first and second detected signals to generate a received linearized signal having substantially zero second-order modulator-induced distortion and zero third-order modulator-induced distortion. - View Dependent Claims (9)
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10. A system for providing a linearized signal over a communication link, comprising:
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a first source producing a first signal of a first wavelength at a first source output;
a second source producing a second signal of a second wavelength at a second source output;
a modulator having a first modulator input in communication with said first source output, a second modulator input in communication with said second source output, a first modulator output and a second modulator output, wherein said modulator differentially modulates said first and second signals from said first source output and said second source output, respectively, to produce a modulated first signal and a modulated second signal;
a first detector in communication with said first modulator output and having a first detector output, said first detector producing a first electrical signal at said first detector output in response to said modulated first signal;
a second detector in communication with said second modulator output and having a second detector output, said second detector producing a second electrical signal at said second detector output in response to said modulated second signal; and
a processor having a first processor input in electrical communication with said first detector output, a second processor input in electrical communication with said second detector output, and a processor output, wherein said processor performs a linear operation on said first and second electrical signals to generate a linearized output signal having substantially zero second-order modulator-induced distortion and zero third-order modulator-induced distortion at said processor output in response to said first and second electrical signals. - View Dependent Claims (11, 12, 13)
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Specification