| 摘要 |
<p>In an optical communication system with a fiber-optic amplifier which includes a wavelength-selective fiber-optic coupler for coupling pump light into the amplifying length of fiber, an additional optical signal, e.g., a service-channel signal, is transmitted from the location of the fiber-optic amplifier in one direction or the other by being used to modulate the pump light. Since the pump light is not completely absorbed in the amplifying length of fiber, a sufficient portion is transferred from the length of fiber into the optical waveguide of the optical communication system and passes down the optical waveguide to the end point of the communication system. There, it is coupled out and passed to an optical receiver from whose output the transmitted additional signal is recovered by demodulation. To prevent the modulation of the pump light from modulating the amplification brought about by the amplifying length of fiber, the additional signal is modulated onto a carrier wave of sufficiently high frequency, and the resulting signal is used to modulate the pump light.</p> |
