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The design of application-specific integrated circuit (ASIC) is at the core of modern ultra-high-speed transponders employing advanced digital signal processing (DSP) algorithms. This manuscript discusses the motivations for jointly utilizing transmission techniques such as probabilistic shaping and digital sub-carrier multiplexing in digital coherent optical transmissions systems. We firstly report the key-building blocks of high-speed modern DSP-based transponders working up to 800G per wave. Secondly, we show the benefits of these transmission methods in terms of system level performance. Finally, we report, to the best of our knowledge, the first long-haul experimental transmission -e.g., over 1000 km -with a real-time 7 nm DSP ASIC and digital coherent optics (DCO) capable of data rates up to 1.6 Tb/s using two waves (2×800G).

We examine both theoretically and experimentally rapid polarization transients generated by mechanical impacts on dispersion compensation modules (DCMs). In our experiments, the transient response of the output polarization to sudden mechanical impacts is found to remain constant among successive measurements. That is, the Stokes vector traces the same path over the Poincaré sphere provided that the interval of time between measurements is less than the time associated with the slow thermal drift of the fiber birefringence profile. Experimentally we can measure angular velocities (AVs) of the Stokes vector over the Poincaré sphere exceeding 100 krad∕s. We demonstrate theoretically with a simple model for the excitation that the patterns of the AV observed in experiments can be reproduced through simulation and that the amplitude of the AV increases with the volume of the fiber affected by the impact. Our model is sufficiently simple to be employed in system simulations.

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