We present experimental results concerning a new alloptical
technique that multiplexes two binary signals into a
quaternary one (4-ASK). The technique is based on parametric
amplification. Values of the quaternary levels obtained
experimentally, as a function of the extinction ratios of the binary
input signals, show a rather good agreement with the simulated and
the analytical results. The generated 4-ASK signals were
propagated through 75 km of standard single-mode fiber and
experienced eye penalties of only 0.5 dB. This indicates the
robustness of the technique for practical applications in
metropolitan area networks.
