Methods of making an optical fiber filter

A method of making an optical filter, said method comprising the steps of:

• providing first and second pairs of ferrules each of which includes a longitudinal extending passageway and a longitudinal axis;
• causing an optical fiber to be disposed in the passageway of each ferrule;
• causing a mirror to be formed on an end surface of one ferrule of each pair such that the mirror covers the passageway which opens to the end surface;
• positioning the other ferrule of each pair with the one ferrule of said each pair to cause the passageways to be aligned and to cause an end surface of the other ferrule to abut the mirror on the end surface of the one ferrule;
• causing the other ferrule of each pair to become attached to the one ferrule of each pair in the aligned position to provide a ferrule assembly;
• severing the one ferrule of each pair in a plane normal to the longitudinal axes of the ferrules at a distance from the mirror which is small relative to the length of the ferrule to provide a wafer having a newly formed end surface;
• and
• positioning the ferrule assemblies to align the passageways and to cause the spacing between the newly formed end surfaces of the wafers to be a predetermined value.