In-line optical modulators with low insertion losses and high maximum optical powers are required for Q switching and cavity dumping of fiber lasers as well as for nonlinear optical-fiber experiments. We report the design of polarimetric all-fiber modulators based on optical-fiber birefringence modulation combined with an all-fiber polarizer. Birefringence modulation involves a piezoelectric ceramic tube. This simple technique permits efficient low-frequency and high-frequency harmonic modulation, up to the megahertz range, as well as modulation of pulses shorter than 1 micros.