Optical Front-Ends for Low-Cost Laser-Based 10-Mbps Free-Space Optical Transceiver

Implementation of a low-cost full-duplex 10Mbps optical transceiver for free-space optical data communication is presented. By employing easy-to-find electronic components, the transceiver consists three main parts namely interface circuit, transmitter and receiver. The transmitter - based on a simple inverter circuitry, drives a laser diode emitting 635nm visible red light. The incoming light signal is focused via 10-cm-diameter lens onto a photodiode SFH203. The received signal current from the photodiode is converted to signal voltage by a resistive-feedback transimpedance amplifier, differentiator, and limiting amplifier and consequently delivered to the interface circuit. 10Mbps Ethernet link between two personal computers situated 300 meters apart has been successfully tested