Photodetection Of Modulated Light Of White RGB LEDs With A-SiC:H Device
Paula Louro, Manuela Vieira, Manuel A. Vieira, J. Costa
Volume 3, Issue 5, Page 366-371, Year 2018 | DOI: 10.5185/amp.2018/410
Keywords: a-SiC: H technology, LED, visible light communication, photodetector, optical sensor, positioning.
Abstract: We propose the use of Visible Light Communication (VLC) for localization services and navigations. The proposed lighting system supplies the dual function of lighting and data transmission. It uses commercial RGB white LEDs for the generation of the light and of the modulated optical signals that are transmitted in free space using an on-off coding scheme. The red, green and blue emitters of white LEDs are independently modulated, transmitting each different information. The photodetector is a multilayered device based on a-SiC:H, designed for the detection of visible optical light. The generated electrical signal by the photodetector is strictly related to the input optical excitation and its demodulation and decode enables the identification of the input light signals that carry the information necessary to perform the positioning and navigation tasks. The photodetector works as an active optical filter presenting self-amplification at selectable wavelengths. It is a multilayered device composed by two stacked pin photodiodes fabricated between conductive transparent electrical contacts. The positioning system includes multiple, identical navigation cells. The decoded signal by the photodetector identifies the input emitter cell and supplies enhanced accuracy within the spatial region covered by the cell. The methodology used for the photocurrent signal processing involves Fourier transform analysis for frequency identification and the use of a photodetector with spectral selective properties of wavelength identification. An algorithm to decode the information is established and the positioning accuracy is discussed. The experimental results, confirmed that the proposed VLC architecture is suitable for the intended application. Copyright © 2018 VBRI Press.