Reconfigurable switching of orbital-angular-momentum-based free-space data channels.

Light beams can carry orbital angular momentum (OAM) such that a helical phase front twists along the direction of propagation. OAM beams have been demonstrated in a wide variety of applications and have been found to offer a new orthogonal degree of freedom for multiplexing independent data streams for high-capacity point-to-point optical communications. However, to enable their efficient use in reconfigurable networks, approaches must be developed to manipulate OAM beams. We demonstrate OAM-based reconfigurable optical switching functions among multiple OAM beams. Selective data switching among three 100 Gb/s quadrature phase-shift keying OAM channels was achieved with a 2.1 dB optical signal-to-noise ratio penalty. The scheme of selective OAM-beam manipulation can be potentially cascaded to realize an arbitrary n×n switching function.