Abstract:
A passive optical link for duplex data transmission operating at 20 Gb/s is
designed using a single laser and fiber. A transmission distance of 55km is
achieved by providing a cost efficient design with a low complexity by utilizing
wavelength conversion technique which allows us to reuse the downlink signal
for the uplink transmission over the same transmission fiber using different
wavelengths as well as eliminating the need for a separate laser at the user
end. The wavelength converter used is designed by utilizing the Self Phase
Modulation properties of a Hightly Nonlinear Fiber of length of 1 km. The
simulation setup consists of a downlink signal from two users modulated with
DP-QPSK format operating at 1552 nm having a total bitrate of 20 Gb/s.
Two different wavelengths 1550.2 nm and 1553.8 nm are generated from the
downlink signal by using HNLF based Wavelength Converter. The uplink
data from two users each having a bit rate of 10 Gbps is modulated on these
two wavelength converted signals using OOK modulation and added together
to send back over the same 55km fiber. The simulation setup and results are
provided. BER curves and eye diagrams of the received uplink and downlink
signal over a duplex transmission single fiber link are provided.
