Fig. 2: Examples of multi-core optical fiber devices.
From: Maximizing quantum discord from interference in multi-port fiber beamsplitters

a 4 × 4 multi-core fiber beam splitter. b Single-mode to multi-core fiber multiplexer device.
From: Maximizing quantum discord from interference in multi-port fiber beamsplitters

a 4 × 4 multi-core fiber beam splitter. b Single-mode to multi-core fiber multiplexer device.