Experimental demonstration of 20 Gbit/s data encoding and 2 ns channel hopping using orbital angular momentum modes.

We explore the use of the spatial domain as a degree of freedom for data encoding and channel hopping. We experimentally demonstrate data encoding at 20  Gbit/s using four possible orbital angular momentum (OAM) modes. The influence of mode spacing and time misalignment between modal channels on the switching crosstalk and bit-error rates is investigated. We find that the use of adjacent modes with a mode spacing of one introduces an extra power penalty of 3.2 dB compared with a larger mode spacing. Moreover, we demonstrate reconfigurable hopping of a 100  Gbit/s quadrature-phase-shift-keying (QPSK) data channel between four OAM modes with a 2 ns switching guard time. The results show that the power penalties for different hopping rates and mode spacings are less than 5.3 dB.