High-Speed Li-Fi Data Transfer Using Laser Communication

This high-speed Li-Fi data transfer system operates by converting digital electrical data into modulated light signals for wireless free-space transmission. At the transmission end, a USB-to-UART converter module receives serial data from a computer, which is then used to drive a BC547 NPN transistor acting as a switching element. This transistor rapidly modulates the current flowing through a laser diode, implementing On-Off Keying (OOK) modulation to translate the data stream into rapid pulses of laser light. Across the transmission path, a BPW34 photodiode acts as the optical receiver, converting the incoming light pulses back into minute electrical current variations. Because these received analog signals are often weak and noisy, they are routed into an LM393 comparator. The comparator acts as a signal conditioning stage, squaring up the analog waveform by comparing the photodiode's output against a reference threshold to produce crisp, clean digital pulses. Finally, the conditioned digital signal is routed back through the UART interface to complete the wireless data link across the breadboard setup.