Abstract: A method of fabricating an optical waveguide fiber that includes the steps of providing a cylindrical glass optical fiber preform having a longitudinally extending centerline hole, and closing the hole under conditions suitable to result in uniform and symmetric hole closure. The method may include first plugging a first end and a second end of the centerline hole to prevent gas flow therethrough. The method preferably involves closing the centerline hole of the preform by drawing the preform down into an optical waveguide fiber.

Abstract: An optical waveguide fiber having a high threshold for stimulated Brillouin scattering. The optical fiber preferably has large optical effective area, and further preferably has a low zero dispersion wavelength.

Abstract: An optical waveguide fiber having a high threshold for stimulated Brillouin scattering. The optical fiber preferably has large optical effective area, and further preferably has a low zero dispersion wavelength.

Abstract: A system for measuring the state of polarization (SOP) of an optical signal. The system includes a tunable local oscillator providing a local optical signal. A polarization transformer is operatively connected to the local oscillator and transforms the local optical signal to a selected one of a plurality of polarizations. A coupler combines an optical signal from the polarization transformer with an input optical signal from an optical system. A heterodyne detector is operatively connected to the coupler to detect the beat frequency of the signal from the coupler and provide an output signal that can be utilized to determine the state of polarization of an input optical signal.

Abstract: A polarization mode dispersion compensator corrects polarization mode dispersion in an optical signal having a fast polarization mode component, a slow polarization mode component and a time differential between the components. The compensator includes a phase shifter and a variable delay section. An input of the phase shifter is coupled to an optical device that provides an optical signal that exhibits polarization mode dispersion. The phase shifter functions to rotate the optical signal principal states of polarization to a desired orientation. The variable delay section includes an input, an output and at least one optical fiber delay line. The input of the variable delay section is coupled to the output of the phase shifter and the desired orientation of the optical signal principal states of polarization are substantially rotated to be in alignment with one of a fast axis and a slow axis of each of the one or more fiber delay lines.

Abstract: Disclosed is a tunable optical filter which may be used in telecommunications systems. The filter comprises a single mode optical waveguide containing a grating. The resonance wavelength of the filter is changed by changing the boundary condition at the interface between the cladding layer and an additional layer applied to the outer cladding layer surface. This boundary condition is changed by changing the refractive index of the additional layer. Means for changing the refractive index of the additional layer include establishing a structural resonance in the additional layer, or forming the additional layer from electro-optic or piezoelectric materials.

Abstract: A system for measuring the state of polarization (SOP) of an optical signal. The system includes a tunable local oscillator providing a local optical signal. A polarization transformer is operatively connected to the local oscillator and transforms the local optical signal to a selected one of a plurality of polarizations. A coupler combines an optical signal from the polarization transformer with an input optical signal from an optical system. A heterodyne detector is operatively connected to the coupler to detect the beat frequency of the signal from the coupler and provide an output signal that can be utilized to determine the state of polarization of an input optical signal.

Abstract: A variable delay device of the type used to correct for polarization mode dispersion in a signal transmitted over an optical communications system. In an exemplary embodiment, the variable delay device uses a plurality of polarization rotators and delay elements aligned in series and alternating with one another. The polarization rotators map the fast polarization mode component of the incoming optical signal to the slow axes of one or more delay elements, to achieve a desired pattern of relative incremental delays which total the initial differential delay being compensated. The delay elements may have uniform or non-uniform incremental delay values, and the polarization rotators may be selectively actuated to achieve the desired pattern of delay values corresponding to the intended total delay.

Abstract: Disclosed is a dispersion managed optical waveguide fiber. The power loss due to four wave mixing is kept low by making the waveguide from sub-lengths of fiber which have non-zero dispersion. The sign of the total dispersion of the sub-lengths is made to alternate along the length of the waveguide, thereby allowing the total dispersion of the waveguide to be managed to a pre-selected target value. It has been discovered that the best performance is obtained when the zero dispersion wavelengths of the sub-lengths are widely and asymmetrically separated. Advantages are realized when the core refractive index profile is changed for sub-lengths having total dispersion of different sign.

Abstract: A single mode optical waveguide having reduced polarization mode dispersion and a method for making such a waveguide is disclosed. Perturbations are introduced into the waveguide core to couple power between the two polarization modes. A model calculation shows that the perturbation length may be of the order of the correlation length. The inventive waveguide is robust in that polarization mode dispersion is reduced even if perturbations are impressed on the fiber after manufacture.

Abstract: Disclosed is a single mode optical waveguide fiber having periodic perturbations in the core to provide a birefringence which mixes the polarization modes of launched light. In addition, perturbations are introduced into the core which serve to manage total dispersion. The total dispersion of pre-selected segments of the waveguide are caused to change sign so that the sum of products, total dispersion times length, algebraically add to a pre-selected value. The two distinct core perturbation types serve to control both polarization mode dispersion and total dispersion. Methods for making the subject waveguide are also discussed.