Optical ADD/DROP filter and method of making same

The invention pertains to optical wavelength division multiplexers/demultiplexers (WDMs)), sometimes termed ADD/DROP filters, and particularly dense wavelength division multiplexers/demultiplexers (DWDMs). The invention is an optical ADD/DROP filter suitable for dense wavelength division multiplexing/de-multiplexing. It comprises an optical bench having a longitudinal V-groove into which the optical components of the ADD/DROP filter are passively aligned and bonded. The bench further includes first and second pairs of opposed, spaced, vertical members at each end between which a fiber array block is inserted. In the method of constructing the ADD/DROP filter, an interference filter is bonded to a first collimating lens. Then, the first collimating lens with the interference filter attached thereto and a second collimating lens are placed in the V-groove of the bench where they are passively aligned. The two collimating lenses are then bonded to the bench. Fiber array substrates are inserted between the pairs of opposed, spaced, vertical members and a UV transparent block is inserted on top of each fiber array between the corresponding pair of opposed, spaced, vertical members. The fiber arrays are actively aligned. After proper alignment is achieved, adhesive is wicked into the spaces between the fiber array, the block and the vertical members. The adhesive is then cured.