Abstract: A single-mode elliptical core optical fiber (15) suitable for the transmission of solitons has a core aspect ratio that changes along the length of the fiber to provide a fiber dispersion that monotonically decreases along the fiber from one end thereof to the other. The fiber preform (30) is drawn from a draw blank (10) having a glass core (11) surrounded by cladding glass (12) and having apertures (13) that are diametrically opposed with respect to the core (11). The cross-sectional area of the void space within the apertures (13) varies with respect to the longitudinal distance along the apertures.

Abstract: Disclosed is an optical waveguide fiber having a compressive outer layer that includes TiO2 in the SiO2 matrix glass. The compressive outer layer includes crystalline structures containing TiO2 that are predominately rutile. Also disclosed is a method for making an optical waveguide fiber having a compressive outer layer. The compressive outer layer can contain an additional metal oxide that is preferentially lost from the outer layer, instead of the TiO2, during the drying and consolidation step.

Abstract: An optical fiber path in a light amplifying apparatus such as a ring laser, figure eight laser, or nonlinear optical loop mirror, comprises circularly birefringent fiber in order to generate twisted solitons. The light being amplified will follow the pitch of a principle axis of the circularly birefringent fiber as it passes through the optical fiber path. Gain from any other possible polarization lessens as the principle axis polarization constructively interferes upon each round trip. The resulting pulses should have a linear polarization everywhere and the plane of polarization should rotate as a function of space and time. Simultaneous generation of orthogonal, twisted solitons from a single fiber laser source may be accomplished by not placing an optical isolator in the fiber laser optical path.

Abstract: A new multiplexer/demultiplexer includes a compound focusing mechanism having adjacent focal points. Multiple images of one or more input pathways for each different wavelength signal are projected onto one or more output pathways. The resulting spectral response is flattened in the vicinity of the center wavelength of each different wavelength signal. The number and spacing of the focal points, as well as the mode field radii of the input and output pathways, can be optimized for desired combinations of channel bandwidth, insertion loss, and crosstalk.

Abstract: Disclosed is a method of controlling the diameter of a glass rod drawn from a glass preform. The diameter control begins as soon as a glass gob begins to move away from a heated portion of the preform. The velocity of the gob is measured and furnace temperature adjusted to maintain gob velocity at a pre-selected target value. By starting diameter control at this early stage of the process, utilization of the preform is improved as is the utilization of the drawing equipment.

Abstract: Disclosed is a single mode optical waveguide fiber having a core refractive index profile in which the profile parameters are selected to provide an attenuation minimum. A set of profiles having the same general shape and dimensions is shown to have a group of profiles contained in a sub-set which exhibit a minimum of attenuation as compared to the remaining members of the set. The members of the sub-set have been found to have the lowest effective group index, n.sub.geff, and the lowest change in .beta..sup.2 under waveguide fiber bending.

Abstract: Four-wave mixing of transmitted signals in a lightwave transmission system is reduced by (1) grouping the signals in pairs of adjacent frequencies, (2) increasing the frequency of every other pair by a fixed amount, and (3) decreasing the frequency of the remaining pairs by the same fixed amount, where the fixed amount is less than the permitted variation of the ITU grid.

Abstract: A procedure for assembling ends of optical fiber into a sheet where adhesive is deposited into parallel grooves in a top surface of a substrate. The optical fibers are placed into the grooves with one optical fiber per groove. A portion of each of the optical fibers, including the ends, extends beyond an edge of the substrate. A plate is pressed against the substrate to hold the optical fibers in the grooves. The plate has a flat surface which extends beyond the edge of the substrate and over the portion of each of the optical fibers extending beyond the edge of the substrate. A lip is contacted with and pressed against each of the optical fibers extending beyond the edge of the substrate to press the optical fibers against the flat surface of the plate. The adhesive is allowed to harden during the lip press to adhere the optical fibers and the plate to the substrate to form the sheet.

Abstract: Disclosed is an all waveguide fiber wavelength converter which makes use of modulational instability to convert signal wavelength over a conversion bandwidth while maintaining low pump laser power relative to other wavelength conversion devices such as those which make use of four wave mixing. The device is operated in the anomalous dispersion region of the waveguides and the zero dispersion of the waveguide in which conversion occurs is less than the pump wavelength so that conversion may occur for signal wavelengths above and below the zero dispersion wavelength. Conversion efficiency is in the range of 25 dB to 30 dB.

Abstract: Disclosed is a single mode optical waveguide fiber having a segmented core design. In particular, the core comprises three segments, each having characteristic dimensions and refractive index profile. By proper choice of index profile in each segment, a waveguide fiber is made which has a mode field diameter of about 9.5, low, positive total dispersion over the operating window 1530 nm to 1565 nm as well as effective area greater than 60 .mu.m.sup.2.

Abstract: A dispersion compensating single mode optical waveguide fiber designed to change the wavelength window of operation of a link from 1301 nm to 1550 nm. The dispersion compensating waveguide fiber is characterized by a core glass region refractive index profile comprised of at least three segments. The segment on the waveguide center has a positive relative refractive index. At least one segment spaced apart from the waveguide centerline has a negative refractive index.

Abstract: Disclosed is a method of controlling the diameter of a glass rod drawn from a glass preform. The diameter control begins as soon as a glass gob begins to move away from a heated portion of the preform. The velocity of the gob is measured and furnace temperature adjusted to maintain gob velocity at a pre-selected target value. By starting diameter control at this early stage of the process, utilization of the preform is improved as is the utilization of the drawing equipment.

Abstract: Methods for identifying optical fibers which exhibit elevated levels of polarization mode dispersion (PMD) are provided. The methods employ difference traces obtained from optical time domain reflectometer (OTDR) measurements. The presence of a cyclical pattern in such a difference trace has been found to be indicative of a fiber having an elevated level of PMD.

Abstract: The optical component ?4! consists of a substrate made of an optical material that carries at least one integrated waveguide and that is extended beyond the said substrate by optical fibers exiting from the protective housing ?1! ?3! for the component. The housing defines a closed internal cavity ?2! in which the said component ?4! is placed. In accordance with the invention, the said cavity ?2! is sized such as to hold the component ?4! with a certain amount of play ?j.sub.i ! that prevents any significant transmission of stresses between the housing ?1! ?3! and the component ?4!.

Abstract: A waveguide fiber coupler including a tubular element surrounding the coupling region wherein sealed elongated open regions are formed between the fused waveguide surfaces which form a part of the coupler and the tubular element. The coupler exhibits improved properties due to the presence of the elongated open regions. The sealing of the elongated open regions provides for improved environmental stability of the coupler.

Abstract: Disclosed is a tuning method for optical interference devices which comprise at least one plurality of waveguides arranged to produce a preselected phase shift in light transmitted therethrough. The tuning is carried out by irradiating the plurality of waveguides using a source of UV light. The method is faster and more reproducible than other tuning methods known in the art, such as tuning by heat induced dopant diffusion. The method is exemplified by data taken using a Mach-Zehnder interferometer. However, the method is compatible with more sophisticated devices which use integrated waveguides or large numbers of waveguides in the phase changing portion of the device.

Abstract: The demultiplexer comprises: a) an inlet wave-guide (1); b) a plurality of outlet wave-guides (5.sub.i); c) an assembly (3) of adjacent integrated wave-guides functioning in the form of a phase network; d) a mode-expanding wave-guide (12) arranged at the inlet of the inlet connector (2) and connected to the inlet wave-guides (1); and e) a plurality of mode-reducing wave-guides (16.sub.i) arranged at the outlet of the outlet connector (4) and connected in each case to one of the outlet wave-guides (5.sub.i). The mode-expanding guide (12) and the aforementioned mode-reducing guides (16.sub.i) are of identical geometry with a width that varies linearly in accordance with their length, whereby the width of the aforementioned expanding and reducing guides at their connection to the associated connector is defined in order to optimize the width of the band passing through a channel while limiting the cross-talk between the outlet channels (5.sub.i) to a pre-determined level.

Abstract: An optical fiber preform is made by supplying the base glass reactant and the dopant glass reactant to a burner that generates a flame in which a stream of glass particles is produced. The burner moves with respect to a rotating mandrel to deposit layers of glass particles on the mandrel. During the deposition of a portion of the preform, the flow rate of the dopant glass reactant is varied in accordance with a first recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form one of the layers. The flow rate of the dopant glass reactant varies in accordance with a second recipe of dopant flow as a function of burner position as the burner moves longitudinally along the substrate to form a layer adjacent to the one layer. The second recipe is different from the first recipe, and the flow rate of the dopant glass reactant changes during the step of moving the reaction zone to form the one layer.

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 method for side writing Bragg gratings, having minimal birefringence, in a waveguide structure is disclosed. The method employs the orientation of the polarization direction of the writing light beam relative to the long axis of the waveguide structure together with the orientation of the intrinsic birefringence slow axis to effectively minimize birefringence in the subject grating.