REDUCTION OF EFFECTS OF SIGNAL-SIGNAL BEAT INTERFERENCE IN OPTICAL TRANSPORT SYSTEMS

摘要

Disclosed herein is an optical transport system configured to transport an amplitude-modulated optical signal generated at the transmitter using single-sideband modulation of an optical carrier and detected at the receiver using direct optical detection. The receiver is configured to estimate the level of signal-signal beat interference (SSBI) in the electrical signal generated upon direct detection of the received optical signal by first converting this electrical signal into a modified baseband signal configured for single-sideband modulation and then squaring and appropriately scaling this modified baseband signal. The receiver is further configured to subtract the estimated level of SSBI from the electrical signal generated by the direct optical detector and to process the resulting corrected electrical signal to recover the data encoded in the amplitude-modulated optical signal. Example analog and digital circuits for estimating the level of SSBI at the receiver are disclosed.

主权项

1. An apparatus comprising:
an optical detector configured to convert an optical input signal into a first electrical signal proportional to an optical power of the optical input signal; and an electrical signal-processing circuit that comprises:
a single-sideband generator configured to generate a second electrical signal based on the first electrical signal, wherein the second electrical signal is a baseband signal configured for single-sideband modulation;a circuit module configured to convert the second electrical signal into a third electrical signal configured to approximate a magnitude of signal-signal beat interference in the first electrical signal; andan adder configured to subtract the third electrical signal from the first electrical signal to generate a corrected baseband signal; and wherein the electrical signal processing circuit is configured to recover data encoded in the optical input signal based on the corrected baseband signal.