Free-Space Terabit Optical Interconnects

Abstract

The continuous growth of Internet data traffic is progressively increasing the pressure over wireless access technologies. To overcome the imminent bandwidth bottleneck, free-space optics (FSO) is currently deemed as a key breakthrough towards next-generation ultra-high-capacity wireless links. As this technology matures, it is starting to find its place not only in future mobile access networks, but also in applications such as datacenter interconnections, satellite communications and high-frequency trading. To meet the everincreasing demand for high-capacity links, future-proof FSO systems should seek maximum compatibility with state-of-the-art optical fiber systems, which nowadays can already provide data rates per channel in the Terabit/s range. However, the ultra-wideband potential of FSO systems comes at the expense of very tight requirements in terms of optical beam alignment, so that reliable end-to-end communications can be ensured. Following this research challenge, in this work we demonstrate a dynamic single-wavelength 1 Tbps FSO link with high pointing error tolerance, boosted by adaptive probabilistic constellation shaping (PCS) and an active gimbal-based acquisition, tracking and pointing (ATP) mechanism. Our results demonstrate successful indoor FSO transmission over 3 m with enhanced resilience towards pointing errors, enabling to adapt the data rate in the range of 0.8-1 Tbps.

Beyond 5G Fronthaul Based on FSO Using Spread Spectrum Codes and Graphene Modulators

“…[88], and 1 Tb/s was achieved under a single-wavelength FSO system in Ref. [89]. Lastly, a FSO link at 1.28 Tb/s was achieved with the help of multiple wavelengths in Ref.…”

Bandwidth Density Analysis of Coded Free-Space Optical Interconnects

“…For example, if we try to employ the system on small printed circuit boards, such as the ones used in smart phones, where the distance between the source and the detector arrays is in the range of millimeters, the laser beam diffraction could be negligible, and using lenses in such cases would be just a waste of resources. However, if the distance between the source and the detector arrays is large, like the one mentioned in [30] where the distance between the arrays is in the range of 3 m, lenses might be used to mitigate the effect of optical interference.…”

Effect of wavelength accuracy of reconstruction-equivalent-chirp laser arrays on performance of wavelength division multiplexing space laser communication system

“…High capacity FSO connections can be achieved by employing wavelength division multiplexing (WDM) technology. In particular, the use of coherent optical communications together with advanced modulation formats and digital signal processing 4 is a promising approach that has recently stood out; it enables FSO communications at unprecedented per-channel data rates of up to 1 Tbps 5 and aggregated multichannel data rates of more than 14 Tb/s employing the WDM technology. However, the WDM transmission system in FSO communication demands higher technical indicators, especially for the light source at the transmitting terminal because the signals will experience severe degradation in intensity, phase, and polarization caused by the atmospheric turbulence, especially for long distance communication links 6 .…”