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The data center interconnect is moving toward 1.6 Tbit/s, which is posing challenges for reaching a solution that is cost effective and technically feasible. Intensity modulation and direct detection (IM/DD) transmission over O-Band using standard single-mode fiber is a potential low-cost solution. However, limitations imposed by chromatic dispersion and four-wave-mixing (FWM) needs to be understood, such as in the case when operating at 8 x 100 GBaud PAM4 in LWDM configuration. In this paper, a statistical approach has been adopted to evaluate the probability of outage by considering practical link parameter fluctuations such as wavelength variation and drift, polarization variation and the natural variation of the fibers zero dispersion wavelength. Numerical modeling shows that IM/DD can be used up to distances of 5 km if transmission power is maintained under 0 dBm. Coherent transmission can extend the distance beyond 5 km due to its signal processing capabilities. However, it is desirable to reduce its complexity for cost effective and power efficient data center applications. Using dual wavelength transmission and DP-16 QAM transceivers, which share similar components to the IM/DD counterpart, the feasibility of simplifying this architecture is studied. The analysis shows that the complexity of the coherent approach can be reduced without significant penalties for distances up to 10 km.
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