Many mines rely on toxic gas sensors to help maintain a safe and healthy work environment. This report describes a prototype monitoring system developed by the U.S. Bureau of Mines (USBM) that uses light to power and communicate with several remote electrochemical toxic gas sensors. The design is based on state-of-the-art optical-to-electrical power converters, solid-state diode lasers, and fiber optics. This deisgn overcomes several problems associated with conventional wire-based systems by providing complete electrical isolation between the remote sensors and the central monitor. The prototype performed well during a two-week field trial in the USBM Pittsburgh Research Center Safety Research Coal Mine.