A metropolitan-scale SDM testbed under the streets of L'Aquila
Two complementary fiber rings serve the laboratory: a ~6 km ring deployed inside underground multi-service tunnels — exceptionally stable, ideal for precision, coherent, and quantum experiments — and a ~20 km metropolitan ring in traditional urban ducts. Both are accessed directly from the lab in Palazzo Camponeschi.
Multi-core fibers
A 6.29-km cable with 18 MCF strands: twelve coupled-core 4-core fibers (C/L band), four uncoupled-core 4-core fibers (O–L band), two uncoupled-core 8-core fibers (O band). Eleven coupled-core strands are spliced into a span exceeding 69 km for long-haul recirculating-loop experiments.
Few-mode fibers
A dedicated 6.1-km cable with eight identical graded-index FMFs supporting up to fifteen spatial modes in a standard 125-µm cladding. Strands can be concatenated into spans approaching 50 km; multi-plane light conversion (de)multiplexers give selective access to each mode.
Single-mode fibers
Conventional SMFs serve as reference links and support hybrid experiments: SDM coexistence, quantum transmission, distributed sensing, synchronization, and advanced optical networking under realistic field conditions.
Fan-in/fan-out devices and connectorized multi-core pigtails provide flexible access to individual cores and support rapid experimental reconfiguration. The infrastructure was developed within the INCIPICT project, funded by the Italian Government as part of the technological reconstruction following the 2009 earthquake.