Abstract: Because the thermal expansion coefficient ("TEC") of glass is small-to-negligible at low temperatures, traditional fiber Bragg grating ("FBG") sensors and long period grating ("LPG") sensors are not adequately sensitive to accurately measure cryogenic temperature changes. However, as demonstrated herein, the integration of a coating around an optical fiber (the coating having a TEC that is greater than that of the fiber alone) can allow the induction of additional thermal strain in the fiber. In this light, a new sensor for cryogenic temperature measurement has been invented that mechanically amplifies temperature transduction within fiber grating sensors. The invention has the benefit of being useful for measuring non-cryogenic temperature changes as well. The thickness of the coating can be optimized.