Different novel kinds of 3D microstructure manufactured in the cladding of FBG are proposed. Femtosecond laser and special rotary are used to fabricate microstructure such as single thread, double thread and annulus. The thread pitch is 60μm, 80μm controlled by feed and rotary speed. In addition, a thickness of 300nm copper film is coated in the microgrooves by magnetron sputtering technology. Temperature experiment has also been set up and done. Experiment result shows that the FBG sensor with double thread of 80μm is the most sensitive one responding to temperature change. It is approximately five times higher than the standard FBG sensor .This new type of FBG sensor shows great prospect in temperature sensing.
Novel FBG sensors based on cladding microstructures are proposed, which include micro-holes array, single or double spiral and straight groove types. Through depositing different sensitive film, the microstructured FBG sensors can be applied to fiber optic magnetic field sensor, hydrogen sensor and humidity sensor. As a developing example, a spiral type microstructured FBG magnetic field sensor is demonstrated. The testing results show that, the sensitivity of the spiral types probe can be promoted 4-6 times more than that of the non-microstructured standard FBG probe. The double spiral probe is better than the single spiral type.