Improved thermal sensitivity of fibre Bragg gratings using a polymer overlayer

Fibre Bragg gratings have been shown to have a much improved thermal sensitivity when using polymer materials with large thermal expansion coefficients as driving elements. The polymers are fu;ed to the fibres at an elavated temperature and the fibres are under compression instead of tension at the lower temperatures subsequently used. This allows a much wider tuning range of the Bragg gratings as silica can stand much more compression than tension. A sensitivity of 0.15 nm/degrees C in the 1550 nm wavelength regime has been achieved and the Bragg wavelength has been tuned 15 nm in the temperature range 0-100 degrees C.