This paper reviews linear cell radar systems, which are radar systems consisting of many antenna units connected by radio-over-fiber to monitor linear-shaped areas. A linear cell system using a millimeter-wave band can provide high-resolution imaging for foreign object detection on runways. Electro-optic devices play important roles in linear cell systems to provide a conversion between optical and electric signals. This paper describes overviews of such devices including light sources, photodetectors, and optical modulators, etc.