An optical fiber (100A-100D) is provided with a cylindrical core (102) and a first optical cladding layer (104). The core (102) is formed of a core material (105) that is optically transmissive. The core material (105) has a core index of refraction that is continuously variable over a predetermined range of values responsive to a first energetic stimulus, such as thermal energy, photonic energy, magnetic field, and an electrical potential. The core (102) includes a bore (103) axially disposed within the first optical cladding layer (104). The bore (103) is filled with the core material (105). The first optical cladding layer (104) is disposed on the core (102). The first optical cladding layer (104) is formed of a photosensitive material. The photosensitive material has a first cladding layer index of refraction that is permanently selectively configurable responsive to an exposure to a second energetic stimulus. The first optical cladding layer (104) has gratings (114-1, 114-2) inscribed therein.