Constellation reshaping via nonlinear wave mixing for reconfigurable QAM channel manipulation

In this paper, an optical constellation reshaping-enabled reconfigurable quadrature amplitude modulation (QAM) channel manipulation scheme is proposed and verified through simulations. The proposed scheme enables constellation geometric shaping in 8QAM channels, information aggregation/de-aggregation in 16QAM channels, and builds flexible interconnection between nodes using high-order modulation formats. Nonlinear wave mixing-driven constellation manipulation operations are employed, including quadrature de-multiplexing, constellation stretching, and constellation compressing. The system reshapes a 10G Baud star-8QAM signal into rectangular/diagonal/interleaved 8QAM signals, and accomplishes interconversion between 16QAM and quadrature phase shift keying (QPSK) signals. The proposed system mainly contains degenerate phase-sensitive amplifier and single-pump fiber-optic parametric amplifier, the theoretical derivations of which are introduced in detail. The operation transfer functions, signal constellation diagrams, error vector magnitudes (EVMs) and bit error rates (BERs) are calculated and analyzed. For the 8QAM processing, with the input optical signal-to-noise ratio (OSNR) of 25 dB, the reshaped rectangular/diagonal/interleaved 8QAM signals show the receiver OSNRs of 23.6 dB/22.9 dB/32.1 dB, respectively at the BER of 10 − 3 , while for the 16QAM processing, under the input OSNR of 30 dB, the output 16QAM signal shows the receiver OSNR of 28.8 dB when BER is 10 − 2.4 . The proposed optical constellation reshaping system demonstrates exceptional stability and flexibility, constituting a critical enabler for future high-performance optical transmission and transparent networking.