Across-dimensional optical constellation de-aggregations from QAMs to PAMs in optical transparent networks

Abstract

In this paper, an across-dimensional optical constellation de-aggregation scheme is proposed and verified. This de-aggregation scheme builds flexible optical connections between core and edge networks and fills the lack of the conversions between quadrature amplitude modulation (QAM) and pulse amplitude modulation (PAM) formats. 10G Baud quadrature phase shift keying/9QAM/16QAM-to-2×on off keying (OOK)/PAM3/PAM4 constellation de-aggregations are achieved. The enabled constellation manipulations contain polarization-assisted quadrature de-multiplexing and bi-directional vector moving. The key research status of QAM/PAM de-aggregations and adopted theoretical derivations are analyzed and expressed in detail. The signal spectrum, constellations, eye diagrams, transfer characteristics curves, error vector magnitudes and bit error ratios (BERs) during the de-aggregation process are calculated to measure the system performances. With the input optical signal-to-noise ratio (OSNR) of 10 dB/15 dB/20 dB, the de-aggregated OOK/PAM3/PAM4 signals show the receiver OSNR of 19.1 dB/21.9 dB/31.2 dB, respectively, at the BER of 10−3. The proposed scheme presents excellent format scalability and has potential applications in flexible all-optical connections, across-dimensional optical transmissions, and optical transparent networks.