| 摘要 |
A tunable optical amplifier is used as a wavelength-selective high-gain element in a subcarrier-multiplexed fiber optic transmission system for providing a direct optical domain-to-baseband conversion of a selected optical channel. A high-speed diode laser optical transmitter is modulated by a plurality of independent information channels that are carried on separate, appropriately spaced carrier frequencies. An optical receiver, coupled to the transmitter by way of an optical fiber, includes a tunable narrow-bandpass semiconductor laser optical amplifier having a gain bandwidth smaller than wavelength distances between adjacent ones of the carrier frequencies, a photodetector coupled to the output of the amplifier, and polarization controlling means coupled to the fiber in front of the optical amplifier for maximizing gain in the optical amplifier. The optical amplifier is tuned to a selected one of the subcarrier-multiplexed optical channels so that the photodetector provides only the baseband signal present in the selected optical channel.
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