A novel and simple fiber-optic sensor based on a superstructure fiber grating for simultaneous measurement of temperature, axial strain, and transverse load is proposed and demonstrated. By measurement of the shift and split of broadband and narrow-band loss peaks, one can determine the temperature, axial strain, and transverse load simultaneously over the ranges 0-140 degrees, 0-1200 mu epsilon, and 0-0.3 kg/mm, respectively. (C) 2001 Optical Society of America.