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Updated: May 5, 2026

Quasi-light Storage for Optical Data Packets
Published on: February 6, 2014
Adaptive threshold adjustment for signal-distortion-free digital-coherent optical demodulation system
Akito Chiba1, Takahide Sakamoto, Tetsuya Kawanishi
1Advanced Device Research Group, New Generation Network Research Center, National Institute of Information and Communications Technology, 4-2-1, Nukui-Kitamadchi, Koganei, Tokyo 184-8795, Japan. chiba@nict.go.jp
Abstract:
Optical quadrature amplitude modulation (QAM) attracts considerable attention in the enhancement of communications capacity, due to its high spectral efficiency. However, this modulation format is more sensitive to signal distortion than conventional formats, making it more difficult to create, transmit, and detect signals. In this paper, we propose an adaptive scheme for demodulation of the distorted optical signals with paying attention to use of DSP-technology. The scheme is based on the adjustment of the thresholds against the signal distortion. Successful demodulation of optical QAM signals is demonstrated with a sufficiently low bit-error rate.
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