Experimental demonstration of tunable de-aggregation from 16-QAM to 4-PAM for two wavelength multiplexed channels using wave mixing in a single nonlinear element to map constellation onto axes

We experimentally demonstrate tunable de-aggregation of two data carrying optical channels using nonlinear wave mixing. For each channel, the signal and its conjugate are coherently added and subtracted in order to map the constellation points onto real and imaginary axes, respectively. Each of two 10 and 15 Gbaud optical channels with a format of 16-quadrature amplitude modulation (16-QAM) are de-aggregated into two 4-level pulse amplitude modulation (4-PAM) signals. We use the same technique to de-aggregate quadrature phase shift keying (QPSK) signals into two binary phase shift keying (BPSK) signals at baud rates of 10 and 15 Gbaud for both channels. System performance is evaluated in terms of the optical signal-to-noise ratio (OSNR), and penalty of ∼0.7 dB is observed at bit error rate (BER) of 10−3.