This article proposes intrinsic polymer fiber sensors for the performance-based assessment and health monitoring of civil infrastructure systems. Such sensors would allow the dynamic measurement of large strains as required for structures during earthquake loading. Furthermore, the interferometric nature of the sensor permits high accuracy for such measurements. However, the use of the polymer fiber sensors at large strain magnitudes is not without significant challenges as compared to conventional silica optical fiber sensors due to the finite deformation of the fiber and nonlinear photoelastic effects. This article analyzes the implications of the large deformations on the opto-mechanical response of the sensors, derives the sensor opto-mechanical properties to be obtained through sensor calibrations, and demonstrates the data acquisition method to be utilized for the new sensors.