Carrier interferometry pulse shaping for dispersion compensation

摘要

The fiber-optic channel introduces a number of linear and non-linear effects including dispersion (e.g., chromatic dispersion), attenuation, four wave mixing, and self phase modulation. As DWDM (Dense Wavelength Division Multiplexing) systems grow in bit rates per channel and numbers of channels, sensitivity to these effects increases. A recently-proposed, far-reaching solution to counter many channel effects is based on Carrier Interferometry (CI) ultrashort pulses. Specifically, at the transmitter, the Frequency Shifted Feedback Cavity (FSFC) is used to generate an ultra short CI pulse via the superpositioning of N equally spaced frequency components. This ultra short pulse is transmitted over the fiber to the receiver side, where the CI pulse is decomposed into its N frequency components. This enables (1) the cancellation of channel effects such as dispersion via the application of different phases to different frequency components; and (2) the use of low-speed (inexpensive) electronic components. Via dispersion compensation, guard time between adjacent pulses is greatly diminished, leading directly to higher data rates per channel. In this work, we demonstrate the robustness of the proposed CI fiber-optic system to errors in dispersion compensation, suggesting that even when the proposed CI system can not perfectly account for dispersion, it can still achieve excellent performances. This, in turn, indicates that even with imperfect dispersion compensation, guard intervals at the transmit side are still unnecessary in CI systems.