Optical Beamforming Networks Supporting Multibeam and Multicast Operation

In this paper, we validate the intrinsic capability of optical beamforming networks (OBFNs) to support simultaneously multi-beam and multicast operations. Through simulation analyses and assuming operation in the downlink direction of a wireless system, we verify the capability of an OBFN based on Blassmatrix architecture and an OBFN based on true-time delay (TTD) elements to support this hybrid mode of operation by calculating the radiation patterns and the resultant constellation diagrams of the demodulated signals at the corresponding observation angles. Finally, we experimentally assess the performance of a 1×4 TTD-OBFN based on  commercially available components in the case of multicast operation. Using microwave signals at 15 GHz carrier frequency, high order modulation formats and 1 Gbaud symbol rates, we modulate the amplitude of a single optical carrier. After the processing of the modulated signals by the OBFN, we validate its potential to support multicast operation by calculating the BER of the received signals at the corresponding observation angles as a function of the optical power at the output of the OBFN. The BER remains below 10^-3 for received optical power higher than -4 dBm, validating the potential of this OBFN architecture to support multicast operation.