Ultra-dense optical data transmission over standard fibre with a single chip source

TLDR

Integrated micro‑comb technology, enabled by dissipative Kerr soliton modelocking, offers bulk‑like performance in a compact footprint and has driven advances in spectroscopy, microwave photonics, and high‑capacity optical communications. The study aims to demonstrate ultra‑dense data transmission over standard fibre using a single‑chip soliton‑crystal microcomb. The authors employ soliton‑crystal microcombs with 48.9 GHz spacing, enabling 64‑QAM modulation and high intrinsic efficiency without stabilization. They achieved 44.2 Tbps at 10.4 bits/s/Hz over 75 km of standard fibre, with error‑free transmission in both lab and field trials, proving soliton‑crystal microcombs can operate without stabilization in practical networks.

Abstract

Micro-combs [1 - 4], optical frequency combs generated by integrated micro-cavity resonators, offer the full potential of their bulk counterparts [5,6], but in an integrated footprint. The discovery of temporal soliton states (DKS dissipative Kerr solitons) [4,7-11] as a means of modelocking microcombs has enabled breakthroughs in many fields including spectroscopy [12,13], microwave photonics [14], frequency synthesis [15], optical ranging [16,17], quantum sources [18,19], metrology [20,21] and more. One of their most promising applications has been optical fibre communications where they have enabled massively parallel ultrahigh capacity multiplexed data transmission [22,23]. Here, by using a new and powerful class of microcomb called soliton crystals [11], we achieve unprecedented data transmission over standard optical fibre using a single integrated chip source. We demonstrate a line rate of 44.2 Terabits per second using the telecommunications C band at 1550nm with a spectral efficiency, a critically important performance metric, of 10.4 bits/s/Hz. Soliton crystals exhibit robust and stable generation and operation as well as a high intrinsic efficiency that, together with a low soliton microcomb spacing of 48.9 GHz enable the use of a very high coherent data modulation format of 64 QAM (quadrature amplitude modulated). We demonstrate error free transmission over 75 km of standard optical fibre in the laboratory as well as in a field trial over an installed metropolitan optical fibre network. These experiments were greatly aided by the ability of the soliton crystals to operate without stabilization or feedback control. This work demonstrates the capability of optical soliton crystal microcombs to perform in demanding and practical optical communications networks.