Photonics is an enabling technology that can extend the existing or offer new capabilities in communications, optical sensing, and radar for national security. The upper illustration depicts a high-data-rate intelligence, surveillance, and reconnaissance (ISR) concept in which photonics can be used for high-bandwidth
free-space optics and millimeter-wave links, high-resolution lidar imaging sensors, and high-performance
airborne radar systems. The lower illustration depicts a buoyant fiber-optic cable antenna system for
enabling GPS connectivity to submarines. The articles in this issue provide some examples of research and
development at APL that can be applied to these critical mission scenarios.