  In recent years there has been considerable interest in developing photonic
temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to
resistance thermometry. In this study we examine the thermal response of FBGs
over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically
sealed dry Argon environment, that FBG devices show a quadratic dependence on
temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements
indicate that the combined measurement uncertainty is dominated by uncertainty
in determining the peak center fitting and by thermal aging of polyimide coated
fibers.
