Micromachining of an in-fiber extrinsic Fabry-Perot interferometric sensor by using a femtosecond laser

In this paper, the fabrication of an in-fiber micro extrinsic F-P interferometric (MEFPI) sensor is reported, for the first time to the best of our knowledge. A micro-rectangular notch within a conventional single-mode fiber (Corning SMF-28) is ablated by using a near-infrared femtosecond laser and the two surfaces of such a micro notch across the fiber forms a MEFPI cavity. Such a MEFPI sensor has a number of outstanding advantages, such as high integration degree, good reliability, very low temperature sensitivity, easy fabrication, capability of mass-production, low cost, etc, offering great potential for sensing applications.