Agile RF-lightwave waveform synthesis and an optical multi-tone amplitude modulator
First Claim
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1. A waveform synthesizer comprising:
- (a) a RF-lightwave frequency-comb generator for generating a continuous wave comb comprising a set of RE tones modulated onto a lightwave carrier, said set of RF tones comprising multiple upper and lower modulation sideband pairs, the RF-lightwave frequency-comb generator comprising multiple loops each having an optical delay line, the optical delay lines in the different loops having different lengths, at least one photodetector, and an optical intensity modulator, the optical delay lines receiving an optical output of the optical intensity modulator, the output of the optical intensity modulator also being supplied to the multi-tone, frequency selective modulator, the outputs of the optical delay lines being detected by said at least one photodetector, the output of the detector being coupled to the optical intensity modulator, wherein spacing between RF tones in said set of RF tones is determined by a delay through a shortest of the optical delay lines;
(b) a multi-tone, frequency selective modulator coupled to the RF-lightwave frequency-comb generator and configured to produce a modulated RF-lightwave frequency comb; and
(c) a photodetector for producing a synthesized RE waveform from said lightwave carrier and said multiple upper and lower modulation sideband pairs in said modulated RF-lightwave frequency comb.
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Abstract
A waveform synthesizer comprising for synthesizing RF lightwave waveforms in the optical domain. These waveforms are constructed by generating their constituent Fourier frequency components or tones and then adjusting the amplitudes of those frequency components or tones. The apparatus includes: a RF-lightwave frequency-comb generator; and a multi-tone, frequency selective amplitude modulator coupled to the RF-lightwave frequency-comb generator for generating a continuous-wave comb comprising a set of RF tones amplitude modulated onto a lightwave carrier.
108 Citations
47 Claims
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1. A waveform synthesizer comprising:
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(a) a RF-lightwave frequency-comb generator for generating a continuous wave comb comprising a set of RE tones modulated onto a lightwave carrier, said set of RF tones comprising multiple upper and lower modulation sideband pairs, the RF-lightwave frequency-comb generator comprising multiple loops each having an optical delay line, the optical delay lines in the different loops having different lengths, at least one photodetector, and an optical intensity modulator, the optical delay lines receiving an optical output of the optical intensity modulator, the output of the optical intensity modulator also being supplied to the multi-tone, frequency selective modulator, the outputs of the optical delay lines being detected by said at least one photodetector, the output of the detector being coupled to the optical intensity modulator, wherein spacing between RF tones in said set of RF tones is determined by a delay through a shortest of the optical delay lines; (b) a multi-tone, frequency selective modulator coupled to the RF-lightwave frequency-comb generator and configured to produce a modulated RF-lightwave frequency comb; and (c) a photodetector for producing a synthesized RE waveform from said lightwave carrier and said multiple upper and lower modulation sideband pairs in said modulated RF-lightwave frequency comb. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method of synthesizing a frequency translated RF-modulated multi-tone lightwave waveform in the lightwave domain as well as a corresponding RF waveform in the RF domain, the method comprising:
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generating a single frequency optical carrier; generating RF modulation sideband tones on said optical carrier in the lightwave domain; adjusting amplitudes of said sideband tones in the lightwave domain; generating a single-tone lightwave reference; and heterodyning said RF modulation sideband tones on said optical carrier with said single-tone lightwave reference. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35)
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36. An optical multi-tone generator comprising:
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a first optical delay line in a first loop for spacing a comb generated by the a multi-tone optical comb generator; a second optical delay in a second loop line for noise reduction, the second delay line being longer than the first optical delay line; at least one photodetector adapted to detect outputs of the first and second delay lines; an optical intensity modulator in a loop portion common to the first and second loops for driving the first and second optical delay lines; and means for compensating for environmental changes affecting a length of at least one of the first and second optical delay lines, wherein the means for compensating for environmental changes affecting the length of at least one of the first and second optical delay lines comprises a phase shifter disposed in the loop common portion and a feedback circuit including a tone selection filter coupled to the loop common portion and a mixer for mixing the output of the tone selection filter with a reference signal, an output of the mixer being operatively coupled to the phase shifter. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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43. An optical multi-tone generator comprising:
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a first optical delay line in a first loop for spacing a comb generated by the a multi-tone optical comb generator; a second optical delay in a second loop line for noise reduction, the second delay line being longer than the first optical delay line; at least one photodetector adapted to detect outputs of the first and second delay lines; an optical intensity modulator in a loop portion common to the first and second loops for driving the first and second optical delay lines; and means for compensating for environmental changes affecting a length of at least one of the first and second optical delay lines, wherein the means for compensating for environmental changes affecting the length of at least one of the first and second optical delay lines comprises an apparatus for adjusting the length of at least one of the first and second optical delay lines and a feedback circuit including a tone selection filter coupled to the loop common portion and an electronic mixer for mixing the output of the tone selection filter with a reference signal, an output of the electronic mixer being operatively coupled to the length adjusting apparatus. - View Dependent Claims (44, 45)
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46. A method of synthesizing a frequency translated RE-modulated multi-tone lightwave waveform in the lightwave domain as well as a corresponding RE waveform in the RE domain, the method comprising:
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generating a continuous wave comb using an RE-lightwave frequency-comb generator, the continuous wave comb comprising a set of RE tones modulated onto a lightwave carrier, said set of RE tones comprising multiple upper and lower modulation sideband pairs, the RE-lightwave frequency-comb generator comprising multiple loops each having an optical delay line, the optical delay lines in the different loops having different lengths, at least one photodetector, and an optical intensity modulator, the optical delay lines receiving an optical output of the optical intensity modulator, the output of the optical intensity modulator also being supplied to the multi-tone frequency selective modulator, the outputs of the optical delay lines being detected by said at least one photodetector, the output of the detector being coupled to the optical intensity modulator, wherein spacing between RE tones in said set of RE tones is determined by a delay through a shortest of the optical delay lines; generating a modulated RE-lightwave frequency comb based on the continuous wave comb; and generating a synthesized RF waveform from said lightwave carrier and said multiple upper and lower modulation sideband pairs in said modulated RF-lightwave frequency comb. - View Dependent Claims (47)
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Specification