Optical fiber communication system employing wavelength converter for broadband transmission

The present invention uses wavelength conversion to increase the bandwidth of optical communication systems. In an exemplary embodiment, a combination of wavelength conversion and amplification with a discrete optical amplifier (OA) to allow communications systems to operate in wavelength bands lambda ' outside the gain bandwidth of the OA. A transmitter launches signal channels ( lambda 1', lambda 2',..., lambda 'N) that are outside the gain bandwidth lambda . A wavelength conversion device upstream of the amplifier maps channels lambda '1, lambda '2,... lambda 'N to corresponding wavelengths lambda 1, lambda 2, ... lambda N within lambda . The OA directly amplifies the converted signals and a second wavelength conversion device downstream of the amplifier maps the amplified signals back to the original channels lambda '1, lambda '2,... lambda 'N. This increases the capacity of the optical communication systems by facilitating the use of both signals that lie within the OA gain bandwidth lambda and signals that can be converted to wavelengths within lambda . Associated wavelength converters, transmitters and receivers are also described. This approach applies not only to the use of EDFAs, but also to gain-flattening elements, dispersion-compensating fibers, variable attenuators, and any intermediate components having bandwidths smaller than the transmission fiber.