All-Optical PAM4 to 16QAM Modulation Format Conversion Using Nonlinear Optical Loop Mirror and 1:2 Coupler


IEICE TRANSACTIONS on Communications   Vol.E103-B   No.11   pp.1272-1281
Publication Date: 2020/11/01
Publicized: 2020/05/14
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2019OBP0015
Type of Manuscript: Special Section PAPER (Joint Special Section on Opto-electronics and Communications for Future Optical Network)
all-optical signal processing,  modulation format conversion,  nonlinear optical effect,  NOLM,  PAM4,  16QAM,  

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In inter-data center networks where high transmission capacity and spectral efficiency are required, a 16QAM format is deployed. On the other hand, in intra-data center networks, a PAM4 format is deployed to meet the demand for a simple and low-cost transceiver configuration. For a seamless and effective connection of such heterogeneous networks without using optical-electrical-optical conversion, an all-optical modulation format conversion technique is required. In this paper, we propose an all-optical PAM4 to 16QAM modulation format conversion using nonlinear optical loop mirror. The successful conversion operation from 2 × 26.6-Gbaud PAM4 signals to a 100-Gbps class 16QAM signal is verified by numerical simulation. Compared with an ideal 16QAM signal, the power penalty of the converted 16QAM signal can be kept within 0.51dB.