Design, Manufacturing and Testing of Photonic Antennas and Metasurfaces for Smart Public Lighting

Abstract

Public lighting system concessionaires have been adopting strategies and actions to replace conventional lamps with LED (Light Emitting Diode) lamps, aiming for efficiency and savings. However, the potential of this technology goes far beyond mere lighting applications, offering a communication system that is still in the development phase and can be explored as a complementary multiple access system to existing WiFi. Thus, by employing VLC (Visible Light Communication) links, an innovative type of communication network can be built, supporting user mobility and multiple access, formed by small cells (attocells), between which a handover technique must be implemented. This type of network has been named LiFi (Light Fidelity) since it relies on visible light communication for its operation. More broadly, in an outdoor environment where public lighting points can be understood as access points, this type of network can be used with great advantage in Smart Cities applications, where a high level of communication and interaction between its elements is required, along with appropriate interfaces for 5th and 6th generation wireless communication systems, currently under implementation and study, respectively. Among the various challenges, the use of LED arrays in non-conventional configurations can offer innovative solutions for systems that combine lighting and communication. Cartesian or periodic arrays require that the separation between the emitting elements be less than 1 wavelength to avoid the emergence of so-called Bragg lobes or Grating Lobes, which are undesirable in a wireless communication system. Since LEDs have dimensions larger than 1 wavelength, they cannot be arranged in periodic arrays, hence the need to use aperiodic arrays that completely eliminate Bragg lobes. In this context, array configurations based on Vogel's spirals (with Fermat's spiral being a particular case) present solutions with great potential for application. Therefore, we propose here to develop an IR (Infrared) LED array in the form of Vogel's spiral, operating at 850 nm or 940 nm, aiming to develop an efficient OWC (Optical Wireless Communication) system that can operate not only in the transmitter mode (down-link) but also in the receiver mode (up-link). Once the proposed system is demonstrated, it could later be integrated into the same board with a set of LEDs operating in the visible range, aiming at the implementation of a hybrid OWC and lighting system.