The Multiplexing of Six Vortex Modes in a Multicore Photonic Quasi-Crystal Fiber

We propose a photonic quasi-crystal fiber which has five ring-shaped cores in the cross section. It realizes the multiplexing of 6 vortex modes. The fiber is based on SiO2 and has an octuple photonic quasi-crystal structure. It achieves four independent dual-core coupling pairs with the optimization of geometric parameters. By adjusting the thickness of five ring-shaped cores, the fundamental mode (HE11) in the small side ring-shaped fiber cores couple to different higher order vector modes (TE01, HE21, TM01, HE31) in the large center ring-shaped fiber core, which makes the light field transfer from small side cores to large center core and realizes the multiplexing of 6 vortex modes (TE01, OAM(+/-) (+/- 1,1), TM01, OAM(+/-) (+/- 2,1)). The transmission characteristics are analyzed with supermode theory. The Delta n(eff) of adjacent vector modes is larger than 10(-4) due to the thin center ring core. The coupling length (L-c) keeps in the order of 10(-2) m between 1500-1600 nm and the coupling efficiency is larger than 90% in 1550 nm for four dual-core coupling pairs. We believe this design will have great potential in the field of all-fiber vortex mode division multiplexing.

Automated summary

We propose a photonic quasi-crystal fiber with five ring-shaped cores that achieves the multiplexing of 6 vortex modes. The fiber has an octuple photonic quasi-crystal structure based on SiO2 and four independent dual-core coupling pairs. By adjusting the thickness of the ring-shaped cores, the light field transfers from small side cores to a large center core, realizing the multiplexing of 6 vortex modes. The design shows great potential in the field of all-fiber vortex mode division multiplexing.