100 Gb/s to 1 Tb/s Based Coherent Passive Optical Network Technology

Following on from current 1 Gb/s to 10 Gb/s based passive optical networks (PON), IEEE 802.3ca has commenced discussion of the first 100 Gb/s-based PON standard in the form of 100 G Ethernet PON (100G-EPON), in anticipation of growing bandwidth demand by emerging applications such as fixed-mobile convergence for 5G and beyond 5G (B5G) where mobile front-haul and mobile back-haul (MFH/MBF) will require greatly increased capacity of up to 1 Tb/s. In the move toward these 100 Gb/s to 1 Tb/s class PONs, research into the latest coherent technology based PON systems is being pursued due to its high receiver sensitivity at much higher bit rates, superior to current direct-detection based PON systems, aided by the rapid progress of the latest small-scale digital signal processing (DSP) suitable for access spans of less than a few tens of km. In this paper, we review the recent progress of such 100 Gb/s to 1 Tb/s class coherent PON technology. As the key successful factor for realizing 100 Gb/s to 1 Tb/s based coherent PON systems, the latest trends in coherent DSP and the accompanying embedded coherent transceivers are summarized from the point of view of miniaturization. In addition, highlighting the strong progress with the upcoming coherent PON systems, the first demonstration of a 100 Gb/s/λ × 8 wavelengths (800 Gb/s) based real-time wavelength division multiplexing (WDM)-PON system using a simplified DSP suitable for access spans is presented. A 100 Gb/s/λ based time division multiplexing (TDM)-PON system is also introduced, addressing the burst-mode coherent reception technique which will be the main issue for achieving practical TDM-based coherent PON systems.