Kramers–Kronig Receivers for 100-km Datacenter Interconnects

Abstract

In this paper, we review in detail experimental demonstrations of Kramers–Kronig (KK) based direct detection systems with high per-carrier interface rates, high spectral efficiencies, and ∼100-km reach. Two realizations of KK-based receivers are summarized, including single-polarization and dual-polarization versions. Critical aspects of the KK receiver such as the carrier-to-signal power ratio and receiver bandwidth limitations are discussed. We show 220-Gb/s single-diode detection and 4 × 240-Gb/s dual polarization (dual-diode) detection in a WDM system at 5.3 bits/s/Hz spectral efficiency.