Investigation of Coupling Between a Fiber and an Infinite Slab.

We investigate an optical waveguide system consisting of an uncladded fiber core suspended at a constant distance parallel to the surface of an infinitely extended dielectric slab. Fiber and slab are both embedded in a homogeneous dielectric medium. The fate of light, initially launched into the fiber, depends upon the relationship between the refractive index values of slab and fiber. When the refractive index of the fiber is considerably larger than that of the slab, the latter exerts little influence on the wave so that almost no power is transferred out of the fiber.