Security enhancement through high-quality illumination enabled by wavelength-shuffled optical OFDM.

This study presents a novel physical layer security technique that aims to increase the security level by reducing decryption attempts and improving the resistance to security attacks. To achieve this goal, the proposed approach generates signals that resemble Gaussian noise in both the time and frequency domains. This method utilizes a wavelength-shuffled optical orthogonal frequency division multiplexing (OFDM) scheme, which is combined with the standard blue-excited phosphorus lighting approach. Experimental validation of the proposed system demonstrates a secure data rate of 880 Mb/s in the aggregate, followed by a real-time demonstration showing its practicality. Furthermore, the proposed system generates high-quality white light (with a color rendering index of 83 and correlated color temperature of 5040 K), which makes it suitable for practical illumination applications.

Small Molecule Based Organic Photo Signal Receiver for High-Speed Optical Wireless Communications.

The present work describes the development of an organic photodiode (OPD) receiver for high-speed optical wireless communication. To determine the optimal communication design, two different types of photoelectric conversion layers, bulk heterojunction (BHJ) and planar heterojunction (PHJ), are compared. The BHJ-OPD device has a -3 dB bandwidth of 0.65 MHz (at zero bias) and a maximum of 1.4 MHz (at -4 V bias). A 150 Mbps single-channel visible light communication (VLC) data rate using this device by combining preequalization and machine learning (ML)-based digital signal processing (DSP) is demonstrated. To the best of the authors' knowledge, this is the highest data rate ever achieved on an OPD-based VLC system by a factor of 40 over the previous fastest reported. Additionally, the proposed OPD receiver achieves orders of magnitude higher spectral efficiency than the previously reported organic photovoltaic (OPV)-based receivers.

Bi-LSTM-Augmented Deep Neural Network for Multi-Gbps VCSEL-Based Visible Light Communication Link.

With the remarkable advances in vertical-cavity surface-emitting lasers (VCSELs) in recent decades, VCSELs have been considered promising light sources in the field of optical wireless communications. However, off-the-shelf VCSELs still have a limited modulation bandwidth to meet the multi-Gb/s data rate requirements imposed on the next-generation wireless communication system. Recently, employing machine learning (ML) techniques as a method to tackle such issues has been intriguing for researchers in wireless communication. In this work, through a systematic analysis, it is shown that the ML technique is also very effective in VCSEL-based visible light communication. Using a commercial VCSEL and bidirectional long short-term memory (Bi-LSTM)-based ML scheme, a high-speed visible light communication (VLC) link with a data rate of 13.5 Gbps is demonstrated, which is the fastest single channel result from a cost-effective, off-the-shelf VCSEL device, to the best of the authors' knowledge.

Smart License Plate in Combination with Fluorescent Concentrator for Vehicular Visible Light Communication System.

Vehicle-to-vehicle communication based on visible light communication has gained much attention. This work proposes a smart license plate receiver incorporated with a fluorescent concentrator, enabling a fast vehicle-to-vehicle communication with a large field of view and high optical gain. Communication performance is experimentally analyzed using off-the-shelf light-emitting diode-based headlamps for low-latency direct line of sight channel. Additionally, a blue laser diode-based beam-steering and tracking system, through image processing of taillights with a steerable mirror, is investigated. Data rates of 54 Mbps from the headlamps and 532 Mbps from the beam-steering channel with ±25° are demonstrated. In addition, real-time video streaming through the beam-steering channel is presented.

RCS-OFDM enabling full brightness control with power-efficient visible-light communication.

In this Letter, we report a novel optical orthogonal frequency division multiplexing (O-OFDM) scheme that provides power-efficient communication and effective brightness control. The proposed scheme exploits the anti-symmetry property of asymmetrically clipped O-OFDM (ACO-OFDM) and signal reversal, doubling the linear dynamic range and enabling full brightness control. It also generates less nonlinear distortion compared with the conventional ACO-OFDM and does not need additional pulse modulations required in previous work. Following detailed descriptions of the proposed scheme with simulation results, a proof-of-concept demonstration showing the full brightness control maintaining the benefits of the power-efficient ACO-OFDM communication scheme is presented. To the best of the authors' knowledge, this is the first experimental demonstration showing the feasibility of O-OFDM-based dimming control.