Sensitivity and scaling laws of unamplified coherent architectures for intra-data center links beyond 100 gb/s

We present an analytical model that allows predicting the performance of a coherent receiver in an optical amplification-free data transmission over distances of the order of a few kilometres, typical of intradata center communications. The model includes noise contributions from the local oscillator intrinsic RIN, shot noise, thermal noise and the impact of receiver parameters such as the common mode rejection ratio, overall responsivity and bandwidth. Our findings highlight the possibility for coherent detection to be used in short-reach communications, with achievable power budgets well within the limit represented by the maximum admissible optical attenuation for these systems. We use our model to predict scaling laws toward higher bit rate.