Microchanneled Chirped Fibre Bragg GratingsFor Simultaneous Refractive Index and Temperature Measurements

摘要

We report here the fabrication, charaterisation and refractive index sensing of two microchanneled chirped fiber Bragggratings (MCFBGs) with different channel sizes (550m and —1000m). The chirped grating structures were UV-inscribed in optical fibre and the microchannels were created in the middle of the CFBGs by femtosecond (fs) laserassisted chemical etching method. The creation of microchannels in the CFBG structures gives an access to the externalindex liquid, thus inducing refractive index (RI) sensitivity to the structure. In comparison with previously reported FBGbased RI sensors, for which the cladding layers usually were removed, the MCFBGs represent a more ideal solution forrobust devices as the microchannel will not degrade the structure strength. The two MCFBGs were spectrallycharaterised for their RI and temperature responses and both gratings exhibited unique thermal and RI sensitivities,which may be utilised for implementation of bio-chemical sensors with capability to eliminate temperature cross-sensitivity.