Thermal sensitivity studies of fibre Bragg gratings inscribed by high-intensity femtosecond UV laser pulses

摘要

We studied the thermal sensitivity of fibre Bragg gratings (FBGs), fabricated in single-mode standard telecom (SMF-28) and photosensitive Ge/B codoped (Fibercore PS 1250/1500) fibres with high-intensity (140-210 GW/cm~(2)) 264 nm 220 fs laser pulses. The accurate measurement of Bragg wavelength thermal shift in the mentioned fibres brought about the values of 9.62 +- 0.04 and 8.03 +- 0.12 pm/(deg C), respectively. The comparison of the thermal sensitivity values for FBGs made in the same fibres by low-intensity UV irradiation or by another inscription technique (scanning phase mask instead of static one) did not reveal any significant differences. This confirms that the thermal sensitivity of Bragg gratings is determined only by the material parameters of the fibres and does not depend on the inscription mechanism and/or fabrication technique.