Current research on the suppression of vibration in flexible structures using active feedback control has focused on the instrumentation required to implement these control laws, particularly, through the use of embedded sensors and/or actuators for smart structures. In this paper, modal domain optical fiber sensors for smart structure applications are discussed. The authors present preliminary modeling results that show that modal domain optical fiber sensors can be used to sense vibrations in a flexible beam and that this signal can be used in a control system to damp vibrations in the beam. This experiment provides the foundations for the use of optical fiber sensors on more complicated structures such as trusses and plates. The modal domain optical fiber sensor is novel in that it responds to strain in the beam over a significant gauge length, a so-called distributed-effect sensor. The authors discuss the potential of these sensors to improve the performance of the control system and illustrate the use of optical fiber sensors for implementing low-order dynamic compensators for active control of acoustic radiation.