Performance of an experimental optical DAC used in a visible light communication system

In visible light communication (VLC), digital-to-analog (D/A) conversion is normally achieved by using an electrical digital-to-analog converter (DAC). In VLC applications, the performance of this conventional configuration is limited by the non-linearity of the light emitting diodes (LEDs). In this paper, a new form of DAC is both simulated and experimentally demonstrated. By using an array of LEDs, D/A conversion is achieved in the optical rather than the electrical domain. Each LED in the array is switched on or off. The total intensity of the transmitted light depends on the number of LEDs that are switched on. The performance of the new DAC is analyzed in terms of conventional DAC parameters including resolution, monotonicity, dynamic range, integral non-linearity and differential non-linearity.