Solid-state 360° optical beamforming for reconfigurable multicast optical wireless communications

Abstract

Optical wireless communication is an attractive technique for data center interconnects due to its low latency line-of-sight connectivity. Multicast, on the other hand, is an important data center network function that can improve traffic throughput, reduce latency, and make efficient use of network resources. To enable reconfigurable multicast in data center optical wireless networks, we propose a novel 360° optical beamforming scheme based on the principle of superposition of orbital angular momentum modes, emitting beams from the source rack pointing towards any combination of other racks so that connections are established between the source and multiple destination racks. We experimentally demonstrate the scheme using solid state devices for a scenario where racks are arranged in a hexagonal formation in which a source rack can connect with any number of adjacent racks simultaneously, with each link transmitting 70 Gb/s on-off-keying modulations at bit error rates of <10−6 at 1.5-m and 2.0-m link distances.

Coherent Optical Comb Generation in the Joint Space of Frequency and Topological Charge

“…[17] Recently, several free space-based schemes have been reported to tailor the OAM spectrum or generate an OAM comb. [18][19][20][21][22] Furthermore, the spatial and spatiotemporal coherence of these OAM states can be exploited to investigate novel optical phenomena, such as Talbot effect in the OAM spectrum, [23] spatial beam-forming [24,25] and spatiotemporal wavepackets that follow particular trajectories. [26,27] Integrated OAM emitters based on micro-ring cavities, starting from our first report of an integrated optical vortex beam emitters based on siliconon-insulator platform, [17] demonstrated excellent ability of emitting high purity OAM beams with fixed l values at a certain resonance wavelength.…”

“…[ 17 ] Recently, several free space‐based schemes have been reported to tailor the OAM spectrum or generate an OAM comb. [ 18–22 ] Furthermore, the spatial and spatiotemporal coherence of these OAM states can be exploited to investigate novel optical phenomena, such as Talbot effect in the OAM spectrum, [ 23 ] spatial beam‐forming [ 24,25 ] and spatiotemporal wavepackets that follow particular trajectories. [ 26,27 ]…”