Optical transmitting device, optical transmission system, optical transmitting method and optical transmission method
First Claim
1. An optical transmitting device of modulating an optical signal by a first signal and then by a second signal for transmission, the device comprises:
- an optical splitting means for splitting the optical signal modulated by the first signal into split optical signals, the optical signal modulated by the first signal including one or more harmonic distortions of the first signal;
a cancellation signal generating means for generating a cancellation signal from one of the split optical signals, the cancellation signal including a frequency spectrum at least partially overlapped with a frequency spectrum of the second signal;
a combining means for combining the second signal with the cancellation signal; and
a modulating means for modulating the other of the split optical signals with the combined signal.
1 Assignment
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Accused Products
Abstract
In an optical transmission system by frequency-division multiplexing, the interference due to distortions of a first signal against a second signal can be reduced. In the optical transmission system where a modulated optical signal by the first signal is further modulated with the second signal for transmission, distortions of the first signal corresponding to a frequency band of the second signal is extracted. The extracted signal is phase-inverted and then adjusted in phase and amplitude with respect to the distortions of the first signal to obtain a correction signal. By intensity-modulating the first signal containing the distortions by the correction signal, the distortions of the first signal against the second signal can be cancelled out. Alternatively, by intensity-modulating the first signal containing the distortions by a combined signal of the correction signal and the second signal, the distortions of the first signal against the second signal can be cancelled out.
18 Citations
13 Claims
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1. An optical transmitting device of modulating an optical signal by a first signal and then by a second signal for transmission, the device comprises:
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an optical splitting means for splitting the optical signal modulated by the first signal into split optical signals, the optical signal modulated by the first signal including one or more harmonic distortions of the first signal; a cancellation signal generating means for generating a cancellation signal from one of the split optical signals, the cancellation signal including a frequency spectrum at least partially overlapped with a frequency spectrum of the second signal; a combining means for combining the second signal with the cancellation signal; and a modulating means for modulating the other of the split optical signals with the combined signal. - View Dependent Claims (2, 3, 4, 5, 6, 13)
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7. An optical transmitting method for modulating an optical signal by a first signal and then by a second signal for transmission, the method comprises:
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splitting the optical signal modulated by the first signal into split optical signals, the optical signal modulated by the first signal including one or more harmonic distortions of the first signal; generating a cancellation signal from one of the split optical signals, the cancellation signal including a frequency spectrum at least partially overlapped with a frequency spectrum of the second signal; combining the second signal with the cancellation signal; and modulating the other of the split optical signals with the combined signal. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification