Optical link
AssigneeRaytheon Company
InventorRobert Leoni
Life of this patent
Estimating the term…
Abstract
A system having a first optical modulator operates in a non-linear region thereof and fed by: an input radio frequency signal; and, a first optical frequency signal having a wavelength λ2. A second optical modulator operates in a linear region thereof and fed by: a fractional portion of the input radio frequency signal phase shifted relative to the input radio frequency signal by nπ radians where n is an odd integer; and a second different optical frequency signal wavelength λ1. A first photodiode is fed by an output of the first optical modulator. A second photodiode is fed by an output of the second optical modulator and a fractional portion of an output of the first optical modulator. An amplifier is fed by the second photodiode. A subtractor is fed by the amplifier and the first photodiode.
Claims5
An optical system, comprising:
- a main transmission link for modulating an input radio frequency signal with a first optical frequency signal to produce a main signal comprising components of the input radio frequency signal translated in frequency by the first optical frequency along with optical frequency spurious signal components;
- a feedforward optical link for modulating a portion of the input radio frequency signal with a second optical frequency signal to produce a feedforward signal comprising components of the input radio frequency signal translated in frequency by the second optical frequency;
- a receiver fed by the main signal and the feedforward signal for subtracting the optical frequency spurious signal components from the main signal.
A system for translating the frequency of an input radio frequency signal to a n optical frequency output signal for transmission via an optical transmission media to a receiver, such receiver re-translating the frequency of such optical frequency signal to a corresponding radio frequency signal, comprising:
- a main transmission link for modulating the input radio frequency signal with a first optical frequency signal to produce a main signal comprising components of the input signal translated in frequency by the first optical frequency along with optical frequency spurious signal components;
- feedforward optical link for modulating a portion of the input radio frequency signal with a second optical frequency signal to produce a feedforward signal comprising components of the input radio frequency signal translated in frequency by the second optical frequency;
- wherein the receiver:
- (a) extracts the optical frequency spurious signal components produced by the main transmission link and re-translates the frequency of such extracted optical frequency spurious signal components to radio frequency signal spurious signal components;
- (b) re-translates the frequency of the components of the main optical frequency and optical frequency spurious signal components of the main signal to radio frequency components;
- and (c) subtracts the extracted and re-frequency translated optical frequency spurious signal components from the re-translated frequency components of the main signal.
A system for translating the frequency of an input radio frequency signal having radio frequency components to a corresponding optical frequency output signal for transmission via an optical transmission media then re-translating the frequency of such optical frequency signal back to the input radio frequency signal, comprising:
- a first modulator, fed by the input radio frequency signal and a first optical frequency signal, such first modulator being driven by the input radio frequency signal into a non-linear region of such first modulator, such first modulator modulating the input radio frequency signal with the first optical frequency signal to produce a main signal comprising components of the input radio frequency signal translated in frequency by the first optical frequency along with optical frequency spurious signal components;
- a second modulator operating in a linear region thereof and fed by a sample of the input radio frequency signal and a second optical frequency signal for modulating the sample of the input radio frequency signal with the second optical frequency signal to produce a feedforward signal comprising components of the input radio frequency signal translated in frequency by the second optical frequency;
- a receiver comprising circuitry fed by the main signal and the feedforward signal for:
- (a) extracting the optical frequency spurious signal components produced by the first modulator and re-translating the frequency of such optical frequency spurious signal components to radio frequency signal spurious signal components;
- (b) re-translating the frequency of the main signal to a corresponding radio frequency signal;
- and
- (c) subtracting the extracted optical frequency spurious signal components from said corresponding radio frequency signal.
A system, comprising:
- a first modulator operating in a non-linear thereof and fed by:
- an input radio frequency signal;
- and a first optical frequency signal having a wavelength λ1;
- a second modulator operating in a linear region thereof and fed by:
- a sample of the input radio frequency signal phase shifted relative to the input radio frequency signal by nπ radians where n is an odd integer;
- and a second different optical frequency signal wavelength λ2;
- a first photodiode fed by an output of the first modulator;
- a second photodiode fed by an output of the second modulator and a sample of the output of the second modulator;
- a subtractor fed by an output from the second photodiode and an output from the first photodiode.
A method, comprising:
- modulating an input signal having radio frequency components with a first optical frequency signal to produce a main signal comprising components of the input signal translated in frequency by the first optical frequency along with optical frequency spurious signal components;
- modulating a sample of the input signal with a second optical frequency signal to produce a feedforward signal comprising components of the input signal translated in frequency by the second optical frequency;
- extracting the optical frequency spurious signal components produced by the first modulation and translating the frequency of such extracted optical frequency spurious signal components to radio frequency signal spurious signal components;
- translating the frequency components of the main signal to corresponding radio frequency components;
- and
- subtracting the extracted optical frequency spurious signal components from said corresponding radio frequency components.
Dependencies are inferred from the claim text.