Unlocking DSCM-Based Self-Homodyne Coherent Multiple Access Through Comb Distribution and Optical Injection Locking

Driven by the explosive surge in bandwidth-thirsty and time-critical services, the coherent multiple access scheme, enabled by digital subcarrier multiplexing (DSCM), emerges as a promising solution for future optical access networks. However, the reliance on power-hungry digital signal processing and narrow-linewidth lasers puts impractical burden on end-users. Self-homodyne coherent (SHC) scheme provides an appealing coherent-lite solution but lacks the necessary flexible frequency selectivity. In this paper, we incorporate the SHC scheme with comb distribution and optical injection locking (OIL), unlocking its potential for DSCM-based multiple access. By exploiting electro-optic combs to clone the phase of narrow-linewidth lasers at optical line terminals as seeds to end-users and using OIL for frequency-selective regenerations, we achieve filter-less flexible SHC reception in downstream transmission and cost-efficiently generate a narrow-linewidth light source for upstream modulation. Utilizing the proposed techniques together with 100-GHz dense wavelength division multiplexing and space division multiplexing, we successfully demonstrate a 4-wavelength 5 × 12.5-GBd dual-polarization 16-quadrature amplitude modulation (DP-16QAM) DSCM downstream transmission over three cores of a 16.7-km 7-core fiber with only a 6-GHz ONU receiver bandwidth, achieving an ultra-high net rate of 5.042 Tbps (420.2 Gbps × 12) and a receiver sensitivity around −26 dBm. As a proof of concept, we also showcase a 4 × 12.11-GBd DP-16QAM upstream aggregation with a single receiver. Thanks to the filter-less flexible SHC reception and generated narrow-linewidth light source, carrier phase recovery is no longer a challenge for DSCM-based coherent multiple access. Our scheme allows for fine subcarrier granularity of 1.5625 GBd in both downstream and upstream transmissions.