arXiv subjects
Publications and source records attributed to Isaac N. O. Osahon.
We demonstrate a fully bidirectional 1 Gbs Ethernet over OWC link over a 1m free space path using a VCSEL-PIN pair and only commercially available components. The unamplified, transparent system achieves error-free operation, with a latency of less than 25 ns, and a centimetre-scale alignment tolerance.
The demand for energy-efficient high-speed wireless communication, coupled with the rapid rise of IoT devices, requires systems that integrate power harvesting with optical data reception to eliminate the need for charging or battery replacements. Recent advances have explored the use of solar cells as optical receivers for high-speed data detection alongside power harvesting. \acs{GaAs}-based \acp{PPC} provide six times greater electron mobility than silicon- or cadmium telluride-based cells, enabling faster data detection and improved power efficiency. However, their bandwidth is constrained by junction capacitance, which increases with active area, creating a trade-off between power output and data rate. To address this, we propose and test multi-segment \acs{GaAs}-based \Acp{PPC} that serve as both energy harvesters and data detectors. By segmenting the active area into 2, 4, or 6 subcells, forming circular areas with diameters of 1, 1.5, or 2.08~mm, we reduce capacitance and boost bandwidth while preserving light collection. Fabricated on a semi-insulating \ac{GaAs} substrate with etched trenches for electrical isolation, the series-connected subcells optimize absorption and minimize parasitic effects. The \Acp{PPC} were used for an eye-safe 1.5~m optical wireless link, employing \ac{OFDM} with adaptive bit and power loading. The system achieved a world record data rate of 3.8~Gbps, which is four times higher than prior works. The system converts 39.7\% of optical power from a beam of 2.3~mW, although the segmentation increases the sensitivity of the alignment. These findings provide new solutions for off-grid backhaul for future communication networks, such as 6th generation (6G) cellular.
In this paper, we demonstrate a laser-based optical wireless communication (OWC) system employing a 940 nm single-mode (SM) vertical cavity surface emitting laser (VCSEL) and a multi-mode (MM) fiber-coupled receiver, achieving a record data rate beyond 70 Gb/s, while the optical transmit power is below 5 mW. The use of a high speed fiber-optic photoreceiver avoids limiting the communication bandwidth by the receiver, enabling ultra-high capacity and energy-efficient light fidelity (LiFi) links to unlock new applications. This work experimentally validates the feasibility of ultra-high speed indoor OWC systems using a single low-power and low-cost VCSEL for next-generation LiFi connectivity.
Real-time transmission of high-resolution video signals in an uncompressed and unencrypted format requires an ultra-reliable and low-latency communications (URLLC) medium with high bandwidth to maintain the quality of experience (QoE) for users. We put forward the design and experimental demonstration of a high-performance laser-based optical wireless communication (OWC) system that enables high-definition (HD) video transmission with submillisecond latencies. The serial digital interface (SDI) output of a camera is used to transmit the live video stream over an optical wireless link by directly modulating the SDI signal on the intensity of a 940 nm vertical cavity surface emitting laser (VCSEL). The proposed SDI over light fidelity (LiFi) system corroborates error-free transmission of full HD (FHD) and 4K ultra-high-definition (UHD) resolutions at data rates of 2.97 Gb/s and 5.94 Gb/s, respectively, with a measured end-to-end latency of under 35 ns. Since SDI standards support various video formats and VCSELs are high-bandwidth and low-power devices, this presents a scalable and inexpensive solution for wireless connectivity between professional broadcast equipment using off-the-shelf SDI components.
Optical wireless communication (OWC) is a promising technology anticipated to play a key role in the next-generation network of networks, especially as a complementary technology to traditional radio frequency communications, for enhancing networking capabilities beyond conventional terrestrial networks. OWC is already a mature technology with diverse usage scenarios, and can enable integrated applications via wireless access and backhaul networks, dynamic drone and satellite networks, underwater networks, inter- and intra-system interconnecting networks, and vehicular communication networks. Furthermore, novel and emerging technological opportunities such as photovoltaic cells, orbital angular momentum-based modulation, optical reconfigurable intelligent surfaces, organic light-emitting and photo diodes, and recent advances in ultraviolet communications can help enhance future OWC capabilities even further. Moreover, OWC networks can also support value-added services such as enhanced positioning and gesture recognition. Hence, OWC provides unique functionalities that can play a crucial role in building convergent and resilient future network of networks alongside radio frequency and optical fiber technologies.