Experimental spatial-spectral allocation for quantum-classical coexistence over multicore fiber

The convergence of quantum key distribution (QKD) with classical optical networks represents a pivotal advancement in secure communication technologies. This paper presents an experimental investigation of a resource allocation framework for co-transmitting QKD and classical signals through multicore fiber (MCF). We first analyze theoretical model characterizing inter-core noise interference mechanisms between classical and quantum channels over MCF. Building on this analysis, a noise-aware spatial-spectral resource allocation scheme is proposed, coordinating resources across two dimensions: core allocation via a Cartesian coordinate-based hierarchy ensures universal compatibility with arbitrary MCF configurations, while adaptive wavelength assignment dynamically suppresses single or dual noise sources. Experimental validation demonstrates the scheme's superior noise suppression capabilities and enhanced secure key rates compared to benchmark approaches, achieving reductions of ⩾ 4.2 dB in noise photons and improvements of ⩾ 10 kbps in secure key rate. This work establishes a practical foundation for implementing QKD networks within existing fiber infrastructure, advancing the realization of scalable quantum-classical coexistance.