METHOD OF MANUFACTURING A FIBER OPTIC DIRECTIONAL COUPLER

摘要

The fibre optical directional coupler has cladding lapped with lapped portion coated with a substance of the same refractive index as strand. This method is required for strands used in a directional coupler in which the cladding of two fibre strands is removed to form a planar tacing surface. The substance has an index of refraction, approximating that of the strand. It is then determined whether the portion of strand illumination which escapes from the lapped portion has reached a predetermined value to determine whether the lapping has reached the critical zone of the strand.