Abstract
The design of application-specific integrated circuits (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. First, we describe the key-building blocks of modern high-speed DSP-based transponders working at up to 800G per wave. Second, 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).
Highlights
O PTICAL telecommunications have experienced tremendous progress over the last decades
This paper focuses on the application-specific integrated circuits (ASIC) design for digital signal processing (DSP) for high-end transponders employing digital sub-carrier multiplexing (DSCM) and probabilistic shaping (PS)
This architecture had been successful as a first-generation DSP, lurking under the surface is the issue of equalization enhanced phase noise (EEPN) [26] that stems from non-zero laser linewidth (LW) and digital dispersion compensation
Summary
O PTICAL telecommunications have experienced tremendous progress over the last decades. To cope with the current rapid traffic evolution, several options are available, among them: (I) a more efficient management of the resources based on elastic and cognitive optical networks [7]; (II) usage of high-order modulation formats and high symbol rate [22], [23]; (III) implementation of advanced DSP and forward error correction (FEC) algorithms [8]; (IV) transmission with advanced digital communication techniques such as probabilistic shaping (PS) and digital sub-carrier multiplexing (DSCM) [9], [10]; (V) enabling beyond C-band transmission [11]; and (VI) development of new fiber types such as multi-mode and –core [12], [13].
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