Optical Filter-Less WDM for Visible Light Communications Using Defocused MIMO

This paper experimentally investigates, for the first time, a new wavelength-division multiplexing-based visible light communications link based on defocused non-imaging multiple-input multiple-output (MIMO), which removes need tuned optical bandpass filters paired with each receiver. The proposed system is using natural diversity of individual emitting diodes (LEDs) within single source to generate an H-matrix, independent spatial diversity. We show that, by transmitting K-independent sets non-return zero on-and-off keying signals separate wavelengths, received superposed symbols can be demultiplexed. MIMO achieved considering power-current characteristics diode, responsivity photodetector array, and beam spot. empirically verified K = 3 red, green, blue LEDs Q-factors 7.66, 7.69, 4.75 dB, respectively.