LED dynamic electro-optical responses and light-fidelity-application optimization

Commercial light-emitting diodes (LEDs) from different manufacturers were studied by means of impedance measurements in the frequency range between 75 kHz and 10 MHz. Electrical characteristics of these LEDs, such as impedance and resistance, were proven to be strongly influenced by the applied frequencies, the bias values, and the alternating-signal amplitudes. Through these measurements, a specific bias value, which later could be of great importance, was pointed out. Coupled with the optical signal-to-noise ratio measurements, this frequency-, bias-, and alternating-signal-amplitude-dependent impedance shows a close correlation between optical and electrical responses of LEDs, which turns out to be useful for visible light communication. Hence, a new and simple method of light-fidelity optimization through impedance measurements is proposed in this article.