Abstract: Disclosed is a total dispersion and total dispersion slope compensating optical waveguide fiber. The refractive index profile of the compensating waveguide fiber includes a core region having a central segment and two surrounding annular segments. In an embodiment of the compensating waveguide fiber, a first clad layer adjacent the core region has a refractive index lower than that of a second clad layer adjacent the first clad layer. The optical waveguide fiber in accord with the invention has negative total dispersion and negative total dispersion slope over the operating window of the fiber to be compensated. The invention includes a compensated optical waveguide fiber span which includes a high performance waveguide fiber and a compensating waveguide fiber in accord with the invention.

Abstract: An athermalized integrated optical waveguide device in which thermal spectral shifts are inhibited is provided and in which the light transmitting properties are insensitive to temperature variations and fluctuations. The athermalized integrated optical waveguide device has at least two waveguide core arms, preferably comprised of a silica glass, with the core arms cladded with a waveguide cladding composition, preferably a silica glass that has a boron concentration different than the cores. The first waveguide arm and the second waveguide arm have a difference in an effective index thermal slope in order to provide an athermalized device such as an intereferometer on a substantially planar substrate. In addition the at least two waveguide core arms are comprised of path segments having different waveguide core dimensions.

Abstract: Disclosed is a single mode optical waveguide fiber having a core region refractive index profile designed to provide a highly non-linear refractive index. The core index profile of the highly non-linear waveguide is an &agr;-profile which has pre-selected values of relative refractive-index and core diameter so as to retain the advantageous optical waveguide properties of low attenuation, properly placed zero dispersion and cut off wavelengths, low, positive total dispersion over a pre-selected wavelength range, and low dispersion slope.

Abstract: A single mode waveguide coupling to a multimode fiber of a high-bandwidth local optical network is made by a tapered coupler that expands the spot size of the propagating beam to fill additional modes of the multimode fiber. The tapered coupler has a core surrounded by inner and outer layers of cladding. The core and the inner cladding layer are drawn down along their length to force light from the core into the surrounding inner cladding layer. The outer cladding layer confines the expanded beam within the core and inner cladding layer.

Abstract: A reduced size multiplexer/demultiplexer component is achieved by tapering of waveguide ends in any of the input, output array, or phase shifting array of waveguides. Cross talk is limited in the tapered region by requiring that each waveguide in a tapered array have a distinct propagation constant.

Abstract: Optical interference filters are designed with harmonic elements that can be related to Fourier series approximations of desired filter responses. The harmonic elements can be fashioned as individual waveguides of an array arranged in various formats including planar or concentric geometries. The expansion coefficients of the Fourier series correspond to normalized power distributions among the waveguides, and the harmonic components of the series correspond to incremental optical path length differences between the waveguides.

Abstract: The present invention provides environmentally stable interferometric and lattice devices that exhibit low excess loss and polarization dependent loss. The interferometric and lattice devices of the present invention are inexpensive and simple to make. The modal noise at the splices between the device pigtails and the system fiber is minimized or eliminated. The present invention is an optical device for filtering a light signal. The optical device has a tunable spectral response. The optical device includes an optical fiber having a core region and a cladding with refractive index n2. The first core region includes a core having a refractive index n1 and a first fiber coupling regulator integral with the first optical fiber. The first fiber coupling regulator couples the light signal between a first optical path and second optical path and substantially prevents the light signal from coupling into a third optical path.

Abstract: An athermalized integrated optical waveguide device in which thermal spectral shifts are inhibited is provided and in which the light transmitting properties are insensitive to temperature variations and fluctuations. The athermnalized integrated optical waveguide device has at least two waveguide core arms, preferably comprised of a silica glass, with the core arms cladded with a waveguide cladding composition, preferably a silica glass that has a boron concentration different than the cores. The first waveguide arm and the second waveguide arm have a difference in an effective index thermal slope in order to provide an athermalized device such as an intereferometer on a substantially planar substrate. In addition the at least two waveguide core arms are comprised of path segments having different waveguide core dimensions.

Abstract: The invention provides improved methods for reducing polarization mode dispersion (PMD) in single mode fiber by spinning the fiber during the drawing process in accordance with a spin function having sufficient harmonic content to achieve low levels of PMD for commercial fibers for which the beat lengths of the fibers, including the beat lengths of different portions of the fibers, are variable and thus not readily known in advance. The spin functions of the invention take advantage of certain resonances in energy transfer between polarization modes to achieve substantial reductions in PMD for a wide range of beat lengths. Examples of suitable spin functions include frequency-modulated and amplitude-modulated sine waves.

Abstract: A distributed sensor (10) includes a plurality of stages (24, 28, 32, 36, 40) connected in series, each stage incorporating a length of polarization maintaining fiber (12) exposed to a phenomena such as mechanical deformation or temperature to be sensed. Inter-mode couplers are provided between the sensing fibers (26, 30, 34, 38) of the various stages. The overall transfer function of the device at a plurality of wavelengths is deconvoluted to determine the birefringence of each sensing region and does monitor plural phenomena independently of one another.

Abstract: A fiber optic sensor for simultaneously and independently measuring temperature and axial stress. The fiber sensor includes a pair of polarization-maintaining fibers that have known strain and temperature response curves. Each fiber has a plurality of fiber segments in which the elliptical cores are rotated 45° relative to the preceding core segment. Thus, the phase shift induced by temperature or stress in each of the fibers is detected, and the strain and temperature are derived from the detected phase shift. The fiber optic sensor is capable of dual operation. As both a temperature sensor and an axial stress sensor.

Abstract: A wideband polarization splitter and combiner is fabricated using either fiber coupler technology or planar coupler technology. The device splits or combines wideband light signals without losing a substantial amount of spectral information. An antipodal phase generator is used to split a randomly polarized light signal into relatively wideband polarization components for use by polarization sensitive devices. The optical device is fabricated using polarization preserving fibers or waveguides, but it is intended for use in systems employing non-polarization-preserving fibers. The polarization splitter/combiner is also used as the basis for an isolator/circulator and a polarization controller. The polarization controller converts a randomly polarized light signal into a signal having a known and definite state of polarization.

Abstract: An N-port optical wavelength division multiplexer and demultiplexer includes two evanescent wave couplers connected by N optical paths. Each of the optical paths includes wavelength-selecting elements that are used to select specific wavelengths of light. Light signals composed of N wavelengths of light introduced to an exterior port in one of the couplers are split substantially equally among all the optical paths within the coupler, so that each optical path exiting the coupler includes light of all the wavelengths initially introduced to the coupler. The wavelength selecting elements disposed on each optical path are situated to direct the light in a manner such that light of only the selected wavelengths interferes constructively at a given exterior coupler port and other wavelengths interfere destructively. Consequently, optical signals composed of N wavelengths may be demultiplexed such that N optical paths carry light having one wavelength.

Abstract: A Mach-Zehnder filter is provided with a strongly aperiodic transfer function including a broad, sharply defined pass band. The filter can be used in conjunction with optical amplifiers.

Abstract: A single-mode optical waveguide fiber designed to limit power penalty due to four wave mixing and a method of making the waveguide is disclosed. Variations in properties, e.g., radius or refractive index, of the waveguide fiber core provide a total dispersion which varies along the length of the waveguide. The algebraic sum of products of length times total dispersion is controlled to a pre-selected value for each waveguide fiber which makes up a system link Proper choice of total dispersion variation magnitude and sub-length results in a system link wherein a signal travels only short distances in waveguide portions having total dispersion near zero. However, the variation of the total dispersion provides a system link which has a pre-selected dispersive effect on the signal over a selected wavelength range. The dispersive effect on the signal can be chosen to be essentially zero. A number of techniques for fabricating DM fiber are also disclosed.

Abstract: A braking system for an in-line skate. The skate includes a boot mounted on a chassis. A cuff is rotatably mounted on the chassis. The chassis also has a plurality of wheels rotatably mounted thereon. The braking system for the skate includes a brake pad housing which is either fixedly or pivotally attached to a rear portion of the cuff, a brake pad disposed in the housing, and a roller arm rotatably mounted on the chassis. The roller arm is spring loaded so that when the brake is not in use, the roller arm is disposed above the wheels. The roller arm has a bearing assembly disposed therein, so that when the brake is actuated by a rearward rotation of the cuff, the brake pad engages the bearing assembly of the roller arm, thereby causing said bearing assembly to engage at least one of the wheels to slow and/or stop the skate. A rear wheel of the skate may be biased to enhance the braking action and reduce wheel wear.

Abstract: A Mach-Zehnder filter is provided with a strongly aperiodic transfer function including a broad, sharply defined pass band. The filter can be used in conjunction with optical amplifiers.

Abstract: The invention provides improved methods for reducing polarization mode dispersion (PMD) in single mode fiber by spinning the fiber during the drawing process in accordance with a spin function having sufficient harmonic content to achieve low levels of PMD for commercial fibers for which the beat lengths of the fibers, including the beat lengths of different portions of the fibers, are variable and thus not readily known in advance. The spin functions of the invention take advantage of certain resonances in energy transfer between polarization modes to achieve substantial reductions in PMD for a wide range of beat lengths. Examples of suitable spin functions include frequency-modulated and amplitude-modulated sine waves.

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: A method of modifying programs and databases having abbreviated date fields to achieve year 2000 compliancy includes examining an original database to ascertain the location of date fields, creating a supplementary PALM file that includes fully expanded date fields representative of corresponding date fields in the original database and modifying instructions or modules of the original program to access the PALM file for date information instead of the original database. The PALM file contains fully expanded date representations of abbreviated date fields of the original database. The PALM file also includes record identifiers and field identifiers to enable the modified program to access the required date information. Portions of the program requiring modification are identified by scanning for keywords that are generated from an examination of the database and/or from field layout definitions. The program is also examined for related keyword constructs or redefinitions found in the program itself.