Method and apparatus for waveform generation
First Claim
1. A spread spectrum waveform generator comprising:
- (a) a photonic oscillator comprising a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier;
(b) an optical heterodyne synthesizer, the optical heterodyne synthesizer including first and second phase-locked lasers, the first laser feeding the multi-tone optical comb generator and the second laser comprising a single tone laser whose output light provides a frequency translation reference; and
(c) a photodetector for heterodyning the frequency translation reference with the series of RF comb lines on the optical carrier generated by the photonic oscillator to generate a spread spectrum waveform, andwherein the photonic oscillator comprises;
a first optical branch comprising a first optical delay element;
a second optical branch comprising a main optical fiber having a forward direction of light propagation;
a third optical branch, said third optical branch providing a Stokes beam to said second optical branch, said Stokes beam propagating in said main optical fiber in a direction opposite to said forward direction of light propagation; and
a common path, said common path comprising;
an optical portion having an optical modulator providing an optical signal to said first optical branch, said second optical branch, and said third optical branch; and
an electrical portion having at least one photodetector coupled to said first optical branch and said second optical branch, said at least one photodetector producing an electrical signal coupled to said optical modulator.
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Abstract
A spread spectrum waveform generator has a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator is a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers, where the first laser feeds the multi-tone optical comb generator and the second laser is a single tone laser whose output light provides a frequency translation reference. At least one photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate a spread spectrum waveform. A receiver pre-processor may be provided to operate on the spread spectrum waveform.
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Citations
64 Claims
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1. A spread spectrum waveform generator comprising:
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(a) a photonic oscillator comprising a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier; (b) an optical heterodyne synthesizer, the optical heterodyne synthesizer including first and second phase-locked lasers, the first laser feeding the multi-tone optical comb generator and the second laser comprising a single tone laser whose output light provides a frequency translation reference; and (c) a photodetector for heterodyning the frequency translation reference with the series of RF comb lines on the optical carrier generated by the photonic oscillator to generate a spread spectrum waveform, and wherein the photonic oscillator comprises; a first optical branch comprising a first optical delay element; a second optical branch comprising a main optical fiber having a forward direction of light propagation; a third optical branch, said third optical branch providing a Stokes beam to said second optical branch, said Stokes beam propagating in said main optical fiber in a direction opposite to said forward direction of light propagation; and a common path, said common path comprising; an optical portion having an optical modulator providing an optical signal to said first optical branch, said second optical branch, and said third optical branch; and an electrical portion having at least one photodetector coupled to said first optical branch and said second optical branch, said at least one photodetector producing an electrical signal coupled to said optical modulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of generating a spread spectrum waveform, the method comprising the steps of:
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(a) generating a multi-tone optical comb as a series of RF comb lines on an optical carrier; (b) generating a single tone frequency translation reference; and (c) optically combining the optical comb with the frequency translation reference to generate a lightwave waveform suitable for subsequent heterodyning, and wherein the step of generating a multi-tone optical comb comprises; modulating an optical signal from a laser with an optical modulator to provide a modulated optical signal; delaying said modulated optical signal in a first optical branch to provide a first delayed optical signal; propagating said modulated optical signal in a forward direction in a second optical branch to provide a second delayed optical signal; generating Stokes light from said modulated optical signal; injecting said Stokes light into said second optical branch so that said Stokes light propagates in a reverse direction to said modulated optical signal in said second optical branch, wherein said Stokes light acts as a seed for stimulated Brillouin scattering in said second optical branch; photodetecting said first delayed optical signal and said second delayed optical signal to produce an electrical signal; and controlling said optical modulator with said electrical signal. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A multi-tone photonic oscillator comprising:
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a laser producing an optical carrier wave; a first optical branch comprising a first optical delay element; a second optical branch comprising a main optical fiber having a forward direction of light propagation; a third optical branch, said third optical branch providing a Stokes beam to said second optical branch, said Stokes beam propagating in said main optical fiber in a direction opposite to said forward direction of light propagation; and a common path, said common path comprising; an optical portion having an optical modulator receiving said optical carrier wave and providing an optical signal to said first optical branch, said second optical branch, and said third optical branch; and
,an electrical portion having at least one photodetector coupled to said first optical branch and said second optical branch, said at least one photodetector producing an electrical signal coupled to said optical modulator. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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52. A method of generating a multi-tone optical comb, the method comprising the steps of:
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modulating an optical signal from a laser with an optical modulator to provide a modulated optical signal; delaying said modulated optical signal in a first optical branch to provide a first delayed optical signal; propagating said modulated optical signal in a forward direction in a second optical branch to provide a second delayed optical signal; generating Stokes light from said modulated optical signal; injecting said Stokes light into said second optical branch so that said Stokes light propagates in a reverse direction to said modulated optical signal in said second optical branch, wherein said Stokes light acts as a seed for stimulated Brillouin scattering in said second optical branch; photodetecting said first delayed optical signal and said second delayed optical signal to produce an electrical signal; and controlling said optical modulator with said electrical signal. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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Specification