Very high signal to noise ratio transmission through a fiber optic link has been demonstrated for frequencies up to 18 GHz. To achieve this required good laser and photodiode frequency response, high laser and photodiode efficiency, low optical reflections, and a laser with good low frequency noise characteristics. Fiber optic links offer many features which make them attractive for microwave signal transmission. Among these are extremely low transmission loss, small size and weight of components, and immunity of optic fibers from EMI1-3 In recent years, tremendous progress has been made in developing high speed lasers and photodiodes . In addition, many applications require high signal to noise transmission capability. In this paper, the dominant noise sources of fiber optic links will be reviewed and experimental results will be presented for a link with components selected for high signal to noise transmission at frequencies up to 18 GHz.