Patent ID: 7079749

Claim:
A waveguide configuration comprising: a core having an index of refraction and a shear velocity; a first cladding extending about the core having a shear velocity which is less than that of the core and an index of refraction which is less than the core; a second cladding extending about the first cladding, the second cladding having a shear velocity which is greater than that of the first cladding, wherein an optical mode has an effective index of refraction greater than that of the second cladding; and a buffer extending about the second cladding, wherein, the core is selected from the group consisting of: Aluminum doped glass fiber, Aluminum and Phosphorus doped glass fiber, and, Aluminum and Germanium doped glass fiber, and Aluminum and both Germanium and Phosphorus, wherein the first cladding is selected from the group consisting of: Germanium doped glass fiber, Germanium and Boron doped glass fiber, Germanium and Fluorine doped glass fiber, Germanium, Boron and Fluorine doped glass fiber, Boron doped glass fiber and Fluorine doped glass fiber, or Boron and Fluorine doped glass fiber, or the foregoing combinations wherein phosphorus may be substituted for or used in conjunction with Germanium; and wherein the second cladding is selected from the group consisting of: undoped glass fiber.