A new process of femtosecond laser micromachining with ultrasonic vibration aided is proposed. An ultrasonic aided device has been designed, and the laser micromachining experiments of transparent materials have been carried out. The effects of the ultrasonic vibration with different power on surface quality and the drilling depth have been investigated, and the mechanism of the ultrasonic vibration aided laser machining has been analyzed. After introducing the ultrasonic vibration device, the residue debris on surface of the ablated trench is significantly reduced, and the drilling depth is increased. These results show that, ultrasonic vibration can effectively improve the surface quality of material processing, increase the depth of the drilling hole and promote the processing efficiency of the femtosecond laser.
Magnetic sensors utilizing direct magneto-optic field coupling in an optical fiber Bragg grating (FBG) is proposed and demonstrated. The FBG’s cladding is micro-machined into micro-curvities aided by femtosecond laser, and coated with TbDyFe, magnetic sensing element. Number of micro-curvities and laser energy under a laser beam were optimized during FBG micromachining and dramatically improved sensor performance. Six-micro-groove sensor is four times more sensitive as compared to non-micro-grooved standard FBG sample. The effect of 18 mW laser pulse power impacted magnetic sensitivity of magnitude 0.6 pm/mT as compared to 0.14 pm/mT on non-microstructured standard FBG sensor. The depth of the deposited magnetostrictive film was measured as ~5 μm.