Band-Interleaving and Entropy-Loading Subcarrier Multiplexing Modulation for 400G/λ Intra-Datacenter Connections Based on Hybrid Receivers

Towards higher capacity for the next generation Ethernet in datacenters, transmitting high-baud-rate signal is necessary. This work presents a band-interleaving receiver with subcarrier multiplexing (SCM) signaling for systems with excessive transmitter bandwidth and severely limited receiver bandwidth. In the proposed scheme, an ultra-high-bandwidth SCM signal is divided into two sub-bands, and modulated onto the optical carrier through an external modulator. The two sub-bands of the SCM signal are extracted by a wavelength selective switch, and then detected by a direct detection (DD) receiver and a lite-coherent receiver, respectively. This approach halves the receiver-side bandwidth requirement. As a proof of concept, we experimentally achieve the transmission of a 100-GHz SCM QAM signal over 500-m single-mode optical fiber (SSMF), attaining a highest net data rate of 428 Gbps above the 0.8798 NGMI threshold. To our knowledge, this represents a successful demonstration of signal transmission with a Nyquist bandwidth of up to 100 GHz and a net data rate exceeding 400 Gbps per wavelength in a system with severely limited receiver bandwidth of about 61 GHz.