LiFi: Transmitting Data via Light Waves

Built a laser and phototransistor link that pulses binary-encoded text between two Arduinos over light. Built a two-node optical data transmission circuit using dual Arduino microcontrollers, pulsing a red laser diode at 100ms intervals to encode and transmit binary text data across varied distances in free space. Integrated optical components, specifically a phototransistor in series with a 10kΩ potentiometer to convert incoming laser pulses into voltage signals and analyze serial text output.

• Characterized signal degradation across variable path lengths, across 10 trials from 50cm to 300cm to quantify how beam divergence and ambient optical noise impact text recovery accuracy.
• Evaluated physical constraints of low-cost photodetectors, determining that detector surface area, sensor hysteresis, and background light limit accurate data transmission over longer ranges.
• Proposed experimental optimizations, including methods to increase SNR through narrow-band filtering, focused photodiode arrays, and short-wavelength UV sources.