Abstract: A bend insensitive fiber optic cable includes a singlemode fiber, a buffer layer surrounding the fiber wherein a thickest component of the buffer layer has an elastic modulus greater than 515 MPa (75,000 psi), and a jacket surrounding the buffer layer, wherein the jacket has a thickness of at least 1.2 mm. In one preferred embodiment, the buffer layer includes a nylon 12 resin with a nominal elastic modulus of approximately 218,000 psi. In this embodiment, an inner thin component of the buffer layer is made of an ethylene/ethyl acrylate resin so as to facilitate stripping of the buffer layer away from the fiber.

Abstract: A bend insensitive fiber optic cable includes a singlemode fiber, a buffer layer surrounding the fiber wherein a thickest component of the buffer layer has an elastic modulus greater than 515 MPa (75,000 psi), and a jacket surrounding the buffer layer, wherein the jacket has a thickness of at least 1.2 mm. In one preferred embodiment, the buffer layer includes a nylon 12 resin with a nominal elastic modulus of approximately 218,000 psi. In this embodiment, an inner thin component of the buffer layer is made of an ethylene/ethyl acrylate resin so as to facilitate stripping of the buffer layer away from the fiber.

Abstract: The refractive index profile of a multimode optical preform, fabricated by MCVD for example, is modified in the longitudinal direction by removing selected amounts of core material from the wall of a central hole through the preform prior to collapse. The amount of core material to be removed is determined by measuring the refractive index profiles of optical fibers drawn from a number of precursor preforms at various locations along the length of the drawn fibers, averaging their profiles, and then comparing those averages with a desired profile. The refractive index profile is indirectly measured by bandwidth measurements, which are related to the alpha value a selected parameter (e.g., bandwidth) at various locations along the length of a fiber drawn from a previously fabricated preform. This parameter is then compared with desired values of that parameter at the various locations, and the differences are used to calculate the amount of core material that needs to be removed.

Abstract: The present invention provides an optical fiber for use in fiber lasers and amplifiers wherein the optical fiber has a core member surrounded by a cladding member for receiving pump energy and transferring the pump energy to the core member. The optical fiber also has an outer layer surrounding the cladding member. The cladding member has a circular exterior periphery and a predetermined refractive index (nc). The cladding member has an index modified region that directs light to the core member. The index modified region has a stress field portion with a predetermined refractive index (ns). The difference between the refractive index of the cladding member and that of the stress field portion (nc−ns) is within such a range that the stress field portion does not affect the polarization properties of the light traveling in the core member.