Professor Papen's initial work in optical components and systems evolved into cross-disciplinary research and publications in a wide range of areas. Early on, he developed novel optical remote sensing systems (lidars), such as one to characterize the upper atmosphere at the South Pole. Multiple grants from NASA funded Papen's work, including demonstration of the first fiber-based lidar system to measure water vapor. His research has also yielded new techniques for reducing an inherent limitation on the amount of power that can be launched within a fiber, either for remote sensing systems or for communications systems; a patent on the technique has been filed, and a startup company created to commercialize the technology.Papen's current research has shifted from remote atmospheric sensing to photonics and fiber optic communications. One project funded by DARPA explores the application of diversity techniques (used most often to combat random signal degradation in "noisy" communication channels) to less-noisy optical computing systems to increase reliability and reduce overall power. He is developing the ECE department's first lab course dedicated to fiber optics. Papen is also interested in distance learning, and is experimenting with methods to let students do experiments remotely by accessing modern lab equipment online.