Fiber tail assembly with optical signal tap

摘要

A method and optical tap is provided for forming a monitor signal that is a measure of optical power in a guided mode output of an optical modulator. The method and optical tap may monitor the guided mode power without tapping the guided mode light, even when optical power of the radiation modes is non-complementary to that of the output mode. Light from the radiation modes of the optical modulator is coupled into the wall of a capillary through a front face. Separate portions of the radiation mode light are reflected into photodetectors, which form photocurrents that are incoherently added to form the monitor signal.