Abstract: Dispersion is reduced in a graded index optical fiber having a finite number of core layers by introducing slow longitudinal variations into the thickness of each layer. The thickness of each layer varies between maxima and minima, the latter being proximate to zero.

Abstract: Dispersion is reduced in a graded index optical fiber having a finite number of core layers by introducing slow longitudinal variations into the index of refraction of each layer. The index of refraction of each layer varies between a maximum which is proximate in value to the minimum index of refraction of the more central radially adjacent layer and a minimum which is proximate in value to the maximum index of refraction of the next furthermost radially adjacent layer.

Abstract: Directional optical waveguide couplers for use with planar-form optical waveguides or optical fiber waveguides are disclosed. In the coupler arrangements, light energy propagating in a direction of interest in the core of a cladded optical waveguide is first coupled into a selected region of the cladding by a mode coupling means and then coupled out of the selected cladding region by a branching optical waveguide or power tap for subsequent conversion to a representative electrical signal. The selected region of the cladding is isolated from spurious cladding modes by a pair of stripper-absorber means to ensure that the coupled out light energy is derived only from the core-guided modes propagating in the direction of interest.

Abstract: A process for manufacturing preforms from which clad optical fibers having longitudinal, eccentric, azimuthal index inhomogeneities may be drawn. In one embodiment, the known CVD process for making preforms is modified by the use of asymmetric heating to produce circumferentially alternating deposits of doped and undoped glass which act as the fiber core when the preform is subsequently collapsed and drawn into a fiber.

Abstract: An improved technique for producing optical fibers is disclosed. In this technique the optical fiber preform is fabricated by axial deposition from a direction along the preform axis as opposed to radial deposition from a direction perpendicular to the preform axis. The instant technique does not require a cylindrical mandrel and, consequently, the technique does not require removal of a mandrel and the collapse of a non-solid preform prior to drawing. In addition to these advantages, the technique may be used to form optical fibers with highly resolved longitudinal gradations in index of refraction. The resolution of such gradations when formed using the instant technique is limited only by the deposition rate and the ability to rapidly alter the concentration of the material being deposited.

Abstract: In an optical fiber power tap, signal power is coupled out of an optical fiber waveguide by a dielectric body disposed in a coupling relationship laterally offset from an intermediate length of the fiber, and is converted to a representative electrical signal suitable for utilization by a photodetector disposed adjacent to the dielectric body. In accordance with the disclosed invention, the operation of the fiber tap is improved by combining therewith means for coupling a portion of the signal power in the fiber from lower order modes to higher order modes. The mode coupling means illustratively comprises a pair of corrugated plates which is pressed against the fiber to periodically deform a region of the fiber just preceding the fiber tap.