An optical communication link is proposed for high speed point-to-point data transmission. The link incorporates both fiber and optical wireless technologies. Kramer-Kronig coherent detection is used due to its component and implementation simplicity. Spatial multiplexing, via a multi-core fiber followed by a wireless link, and wavelength division multiplexing allow the efficient exploitation of all available degrees of freedom. The link signal-to-noise ratio is estimated when all possible noise sources are taken into account. The impact of link loss and optical amplifier placement on the achievable SNR are studied theoretically. Finally, it is shown that over 1 Tb/s is achievable per wavelength with a 4-core fiber and a simple optical wireless alignment system. An important application of this design would be backhaul and intra-data center links.

A high speed optical wireless-fiber solution was proposed in part I of this research with applications such as network backhaul and data center links. The proposed system is based on the utilization of state-of-the-art modulation and multiplexing techniques in optical fiber and optical wireless communications, including multicore fibers (MCFs) and coherent detection based on Kramer-Kronig (KK) receivers. In this paper, we analyze the performance of the proposed system and compare it with an intensity modulation and direct detection (IM/DD) system. Superior performance of the KK receiver is shown for various modulation formats and optical amplification schemes. We also consider the eye-safety constraint for the optical power as a practical design factor. It is demonstrated that the position of optical amplifiers affects the multiplexing gain and achievable data rate when eye-safety constraint is imposed. Further important challenges for the practical deployment of the system are discussed.

The nonlinear distortion introduced by the dead time strongly limits the throughput of the highly sensitive SPAD-based optical wireless communication (OWC) systems. Optical OFDM can be employed in the systems with SPAD arrays to improve the spectral efficiency. In this work, a theoretical performance analysis of SPAD-based OWC system with asymmetrically-clipped optical OFDM (ACO-OFDM) is presented. The impact of the SPAD nonlinearity on the system performance is investigated. In addition, the comparison of the considered scheme with DCO-OFDM is presented showing the distinct reliable operation regimes of the two schemes. In low optical power regimes, ACO-OFDM outperforms DCO-OFDM with around 4 dB power gain achieved by 16-QAM ACO-OFDM over 4-QAM DCO-OFDM. However, DCO-OFDM is in turn more preferable in high power regimes which extends the maximal tolerable received optical power by 7.4 dB.

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We propose and demonstrate a GaN-based seriesdriven hybrid light emitting diode (SH-LED) device in which broad-area and micro-LED components are interconnected for simultaneous illumination and high-speed visible light communication (VLC) applications. Through theoretical analysis based on an equivalent electrical circuit model and characterization from a fabricated exemplar device with blue emission, it is shown that SH-LEDs combine the advantages of broad-area and micro-LED components by offering high direct-current (DC) optical power output and a fast frequency response. The application of this device to VLC is demonstrated through both the point-to-point and 9 • divergence-angle coverage systems at 3 m transmission distance adopting a DC-biased optical-orthogonal frequencydivision multiplexing modulation scheme. Compared with a point-to-point system using a single micro-LED, that our initial demonstrator SH-LED achieves the same data transmission rate of 3.39 Gbps at forward error correction (FEC) floor of 3.8×10 −3 , but the received DC optical power is improved by over 3 times. For the area coverage system, up to 1.56 Gbps data transmission rates at a FEC floor of 3.8×10 −3 are accomplished by using this device, associated with over 4 times higher received DC optical power compared with that using a single micro-LED.