Detailed volume modulators based on electro-optical and acousto-optic effects are presented. Fiber Bragg gratings (FBGs) have, over the last few years, been used extensively in the telecommunication industry for dense wavelength division demultiplexing, dispersion compensation, laser stabilization, and erbium amplifier gain flattening. Fiber Acousto Optic Modulators (FAOMs) are emerging as powerful tools in this quest, offering unique advantages for a wide range of sensing applications.