A new, to our knowledge, modulator based on a tapered single-mode optical tiber is introduced. The electro-optic device consists of a tapered optical fiber placed on a resonator made of a piezoelectric material. An electrical signal applied to the piezoelectric material makes the taper bend, and that displacement produces a modulation in the intensity of the optical signal traveling through the fiber. This device is very easy to build and is low in cost. Because of its nature, this new device might be very useful in optical fiber sensors. Its performance is analyzed, and the results are discussed. (C) 2001 Optical Society of America OCIS codes: 060.2330, 060.4080, 230.2090, 230.4110.