VARIABLE OPTICAL ATTENUATOR EMPLOYING POLARIZATION MAINTAINING FIBER

摘要

An electrically controllable, variable optical attenuator (VOA) is disclosed, in which polarization maintaining fiber (30) is employed. The fiber (30) is modified to expose the evanescent field of optical energy transmitted therein, by removing material therefrom in a direction parallel to either the fast or slow axis of the fiber (30), while preserving the polarization maintaining property of the fiber (30). A controllable material (160) is formed over the modified portion, to remove optical energy in response to a changeable stimulus applied, which changes the refractive index of the material. Related packaging, material composition and system aspects of the attenuator are also disclosed.