THREE-PORT FILTER AND METHOD OF MANUFACTURE

摘要

A method of manufacturing a filter includes the steps of positioning a collimator assembly including a GRIN lens mounted thereto in a movable fixture, placing a UV or thermally curable adhesive on the periphery of the GRIN lens, moving the GRIN lens into engagement with a filter holder having a filter mounted therein, micro-tilting the filter holder while monitoring the input and output signals of the fibers coupled to the GRIN lens for insertion loss less than about .1 dB, and applying UV radiation through the filter end of the filter holder to initially cure the aligned subassembly. In a preferred embodiment, the resultant subassembly is subsequently stress relieved and thoroughly cured. In another embodiment, UV radiation is applied to the filter holder GRIN lens interface through one or more apertures formed in the side of the filter holder. An optical filter has an input ferrule with an input cone having an axial length greater than about 3 mm to reduce S-bending of input fibers, thereby minimizing resultant insertion losses. The filter includes a holder with an annular seat formed in one end for receiving a filter and a lens-receiving aperture at an opposite end which allows micro-tilting of the filer holder to provide an alignment at an angle of less than about 1 DEG to the axis of the GRIN lens.