A center‐etched single‐mode fiber is designed as a vibration senor to monitor the vibrations of a simply supported beam.The sensor works on transmission power loss due to the mode volume mismatch and flexural strain of the fiber due to the bending in the fiber with respect to the bending of the beam. The sensor has high linear response to axial displacement of about 0.8 mm with sensitivity of 32 mV/10 μm strain. The simple design, small size, immune to electromagnetic interference (EMI), and flexible length are all added advantages that may find a place in industry to monitor the vibrations of the beam structures and bridges. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:75–79, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27240