Short Reach Communication Technologies for Client-Side Optics Beyond 400 Gbps

Xiaodan Pang,Gunnar Jacobsen,Oskars Ozolins,Aleksejs Udalcovs,Sergei Popov,Vjaceslavs Bobrovs,Richard Schatz

doi:10.1109/lpt.2021.3078255

Abstract

Short reach optical communication technologies are increasingly demanded in several fast-evolving application scenarios in both telecom and datacom. Low-cost and low-complexity intensity modulation and direct detection (IM/DD) technologies are challenged to scale up the link rate beyond 400 Gbps by increasing the single-lane rate towards 200 Gbps, to maintain a low lane count in client-side optics. Limited by the bandwidth of both electronics and optoelectronics, and the more pronounced chromatic dispersion in the fiber, such high baud rate systems require the use of digital signal processing techniques with forward error correction (FEC) coding. Therefore, in this work, we first summarize a few potential alternative technologies to the IM/DD for future development and then focus on extending the IM/DD systems towards 200 Gbps lane rate. We study both their capability and their performance limits using numerical simulations and transmission experiments.

Highlights

S HORT reach communications in the fiber-optics can be loosely defined as the optical communication links bridging two locations within ∼100 km [1]
Following the data center networking (DCN) evolution trend, some potential transformations inside the DCs can occur in the short- to mid-term: 1) link rate upgrade to 400 Gbps and beyond; 2) rearrangement of the DCN towards resource disaggregation for more efficient utilization, where the basic building elements become resource blocks instead of servers [3]; 3) adoption of passive/active optical/photonic switches to address the port density, speed, and power consumption issues [4]
We show an experimental demonstration of a 200 Gbps intensity modulation and direct detection (IM/DD) system with high end-to-end bandwidth and low signal processing complexity

Summary

INTRODUCTION

S HORT reach communications in the fiber-optics can be loosely defined as the optical communication links bridging two locations within ∼100 km [1]. Following the data center networking (DCN) evolution trend, some potential transformations inside the DCs can occur in the short- to mid-term: 1) link rate upgrade to 400 Gbps and beyond; 2) rearrangement of the DCN towards resource disaggregation for more efficient utilization, where the basic building elements become resource blocks instead of servers [3]; 3) adoption of passive/active optical/photonic switches to address the port density, speed, and power consumption issues [4]. These transformations will likely require higher link speed and/or higher loss budget. Novel concepts from the industry, like the coherent digital subcarrier-based solutions [22], may impact the choices for the short reach scenarios owing to their unique advantages in supporting data aggregation architectures

TECHNOLOGICAL CHOICES AND RESEARCH STATUS

Findings

CONCLUSION