Integrated all-fiber variable attenuator based on hybrid microstructure fiber

We present a design for modulating light in a single-mode optical fiber by achieving efficient field interaction between the fundamental mode of an ai r-silica microstructure optical fiber and tunable materials incorporated in the air holes of the fiber. This method involves tapering microstructure o ptical fiber where light is guided by the air holes and modulated by a poly mer incorporated in these capillary voids. Using this fiber design, we expe rimentally demonstrate a variable attenuator (loss filter) with 30 dB dynam ic range, insertion loss of less than 0.8 dB, and minimal polarization depe ndence. (C) 2001 American Institute of Physics.