Optical coupler

Abstract

Abstract PURPOSE:To obtain an optical coupler which connects as optical fiber and a thin film optical guide path with a small loss and high stability, by forming the edge of the optical fiber into a taper. CONSTITUTION:The optical coupling part of an optical fiber is formed into a taper with a gentle angle, and at the same time the difference of refractive index is varied between the core and the cladding in accordance with the change of the diameter of the taper. In other words, the normalized frequency V is made constant. The frequency V is obtained from a relation shown by an equation, where n1 and n2 are refractive indexes of the core and the cladding respectively, lambda is the wavelength of the light that propagates the core 16 and (a) is the radius of the core respectively. Such frequency V shows the enclosing function of the electromagnetic field energy of each propagation mode of the light that propagates the core 16. The surface of a light guide path 14 of an optical integrated element 12 is coated with a protective film 17 of SiO2, and then the fiber 11 is connected to the path 14 with an adhesive 18 of the epoxy resin or the like material. In such way, the connection is more reinforced.

Inventors

• 👤 Takao Ito

Bibliographic Details