Controllable fiber optic attenuators and attenuation systems are disclosed for controllably extracting optical energy from a fiber optic, and therefore attenuating the optical signal being transmitted through the fiber optic. In one aspect, material is removed from a portion of the fiber optic, thereby exposing a surface through which optical energy can be extracted. A controllable material is formed over the surface for controllably extracting optical energy according to a changeable stimulus applied thereto, which affects the refractive index thereof. In an improved embodiment, a controllable material is formed over the exposed surface for controlling the amount of optical energy extracted from the fiber optic, and a bulk material is formed over the controllable material, into which the extracted optical energy is radiated. The controllable material has a controllable index of refraction approximately matching the index of refraction of the cladding of the fiber optic, and the bulk material formed over the controllable material has a fixed index of refraction higher than the effective mode index of refraction of the fiber optic. This cladding-driven design varies the effective optical thickness of the controllable material, and therefore effects a controllable attenuation of the optical signal being transmitted in the fiber optic. Attenuation systems including these controllable attenuators, as well as control and sense sub-systems, are also disclosed.