Noise sources in microwave photonic links

This paper presents an overview of the dominant noise sources in microwave-photonic links. The origins of these noise sources are described and their dependence on system and device parameters are outlined. The need for high signal-to-noise ratios in microwave-photonic links makes such links especially sensitive to amplitude and phase noise sources. All such links include a transmission laser, an electrooptic modulator, a transmission medium (such as optical fiber), and a photodetector for converting the microwave signal used to modulate the laser back into an electrical signal. All of these components contribute to the link noise. Complex interactions within microwave-photonic links that couple noise sources to, or distort, the transmitted microwave signals are also listed. In addition,the paper outlines several techniques for suppressing the various noise and distortion effects in microwave photonic links. Finally, the tradeoffs between the various noise-suppression techniques are described. The information provided in this work will aid in the optimization of microwave-photonic links for specific applications. .