Abstract: In accordance with the invention, the fabrication of a grating phase mask is improved by providing a multiple-scan exposure which can provide an accumulated exposure that is effectively phase modulated or modulated rapidly in amplitude. Applicants have determined that exposure scans can be chosen so that each is modulated in amplitude and without modulation in phase, but the accumulated exposure of the multiple scans is modulated in phase and/or modulated in amplitude. The improved method can be used to make phase masks for fabrication of sophisticated fiber gratings such as superstructure gratings.

Abstract: Self-registration systems and methods for dynamically updating information related to a network, are provided. A self-registration system for dynamically updating information related to a network, comprises: a connector comprising an integrated circuit that stores a first block of information; an adapter coupled to the connector; a reader that receives the first block of information from the integrated circuit via the adapter; and a communication line coupled to the adapter via the connector, where the first block of information comprises a first block of information about network elements associated with the integrated circuit, and where the first block of information about network elements associated with the integrated circuit comprises information other than information identifying the connector, the adapter, the communication line and the integrated circuit.

Abstract: In accordance with the invention, an optical fiber transmission system is provided with multiple order PMD compensation to provide enhanced compensation at high bit rates and across a range of frequencies. Specifically, PMD is compensated by a concatenated series of components, each component configured to compensate for the effects of a successively higher order term of a PMD Taylor series approximation. Advantageously, each component comprises a polarization controller and a differential dispersion element of specified order. In an exemplary embodiment, the first order differential dispersion element can be a standard differential group delay (DGD) element. The element of second order can be a differential group-velocity dispersion element, and the third order element can be a differential dispersion slope element. These differential dispersion elements of various orders can be fixed or tunable elements in different embodiments.

Abstract: An optical regenerator enabling matching of self-phase modulation induced spectral broadening and optical regenerator filter center wavelengths and bandwidths for different fiber dispersion values. The regenerator monitors the central part of an input signal spectrum at the output of a non-linear medium and suppresses the power at the center wavelength to allow for a constant spectral broadening for different fiber dispersion values. The regenerator utilizes a control filter to control a variable amplifier via a feedback loop, and the variable amplifier adjusts the power of the signal launched into the non-linear medium to ensure a sufficient self-phase modulation broadened spectrum.

Abstract: Techniques are described for reducing splice loss between a pair of optical fibers. A first fiber is spliced to a second fiber at a splice point. A region of the spliced fibers, including the splice point, is thermally treated to cause a controlled diffusion of dopants in the region. A controlled tension is then applied to the splice region while heating it to a predetermined temperature to produce a controlled change in the splice region's strain state. Further described is a heat and tension station for performing a heat and tension technique on a pair of spliced fibers.

Abstract: Methods and apparatuses negate a measured mechanical twist of an optical fiber by introducing a counteracting twist to bring the net mechanical twist closer to zero, which reduces the fiber's polarization mode dispersion (PMD). A spool of optical fiber having undesirable mechanical twist is mounted and fiber is drawn from the end of the spool to impart a specified counteracting mechanical twist. Additionally, the spool may be controllably rotated by a control system while optical fiber is drawn there from, allowing the system to generate a precise amount of counteracting mechanical twist in the fiber.

Abstract: A glass tube for use in an optical fiber preform is produced by applying a first soot on an end face of a starting member to form an elongated, porous cylindrical soot core having a first density, and applying a second soot including SiO2 on the periphery of the soot core to form a porous soot cladding having a second density greater than that of the soot core at the periphery of the core. The core and the cladding are later heated together at a temperature sufficient for sintering to form a core glass and a cladding glass. Because the soot core collapses at a greater rate than the soot cladding during sintering, the core glass separates or delaminates radially from the cladding glass. The core glass is then removed from the surrounding cladding glass, and the latter is treated to provide a high purity glass tube suitable for use as part of an optical fiber preform.

Abstract: A GRIN fiber lens is fabricated by the steps of providing a graded index glass preform, thinning the graded index preform to remove a sufficient thickness of the graded glass to establish a desired ?n, and drawing a graded index optical fiber from the thinned graded index preform. Thinning, in this context, refers to removal of graded index glass from the outside of the graded index preform so as to reduce its outer diameter. The thinning thus changes ?n which is the refractive index difference between the center of the preform and its outer surface. The graded index preform can be provided by MCVD deposition followed by removal of the starting tube glass, by OVD deposition, by VAD, or by ion exchange fabrication. The thinned graded index preform is advantageously annealed before drawing in order to minimize ripple. And, in a variation of the process, an overcladding can be applied over the thinned graded preform before draw for further adjustment or control of the ?n.

Abstract: A tunable polarization dependent loss element is formed of a fiber including a highly tilted optical grating. The grating is formed at an angle of approximately 45° so as to preferentially scatter one polarization state out of the fiber core while allowing the remaining, orthogonal polarization to propagate unimpeded. By twisting the ends of the fiber grating structure, the orientation of the grating with respect to the fiber optical axis will be changed, modifying the amount of optical signal existing in each polarization state. In one embodiment, both ends may be rotated in the same direction through the same angular displacement, resulting in merely rotating the principle states of polarization in the fiber. Alternatively, the ends of the grating may be rotated (twisted) in opposite directions so as to couple all of the light signal into a single polarization state, reducing the amount of polarization dependent loss to essentially zero.

Abstract: Systems and methods are disclosed for an automatic and continuous supply of coating material to a coating applicator in optical fiber fabrication. The present invention switches from one coating reservoir to another by way of a transitional period in which both coating reservoirs are supplying coating material to the coating applicator. For example, while an in-use reservoir is supplying the coating material to the coating applicator, a standby reservoir is being filled, settled to off gas air bubbles and then slowly pressurized. A sized orifice is used to slowly bleed off pressure from the in-use reservoir at a rate that does not allow the pressure in the in-use reservoir from falling out of a desired pressure range.

Abstract: A perturbed, multimode optical fiber exhibits order-of-magnitude improved capacity attributed to mode mixing—high per-channel bit rate, and large channel number due to large available bandwidth—without the added loss which, in the past, was associated with the perturbation stream.

Abstract: A swept wavelength source for broad bandwidth Raman pump applications includes a source of ultrashort (e.g., picosecond) optical pulses. The pulse train output from the source is then applied as an input to a linear dispersive element (such as a section of negative dispersion-shifting fiber) which functions to “stretch” the ultrashort pulses, causing the pulses to become separated in time, with a continuous shift in the wavelength through the length of the pulse.

Abstract: A ferrule for use in optical fiber connections has an optical fiber containing a bore extending therethrough. Within the bore is a member of shaped memory alloy (SMA) which clamps and affixes the fiber firmly in place within the ferrule without the necessity of cementing the fiber in place. The shaped memory alloy has two states: the initial or primary state and the secondary or deformed state. In the embodiments of the invention, the member is deformed from the initial state to the secondary state and the fiber is inserted in the ferrule. The member is then returned to the primary state in which it firmly clamps the fiber within the ferrule.

Abstract: A long period fiber grating (LPG) device is formed to exhibit a “turn-around-point” (TAP) in a phase matching curve when the group velocities of two propagating modes are matched. When the grating period of the LPG is selected to coincide with the TAP, a large tuning bandwidth is formed. This device has been found to be highly sensitive to changes in the refractive index of the ambient surrounding the LPG (recognizing a change in refractive index as low as 10?4), allowing the device to be used as a sensor for trace elements in the atmosphere. The ability of the TAP LPG to modify the intensity of a propagating optical signal as a function of changes in the refractive dielectric of a surround material also allows for this device to be used as an all-fiber high speed optical signal modulator.

Abstract: Polarization monitoring and control in a lightwave communication system is achieved by using an in-line polarimeter in conjunction with a polarization controller. The devices are readily compact, accurate and therefore capable of implementation in a variety of system applications. In one embodiment, a polarimeter and controller can be coupled together by a feedback loop between the polarimeter output and the controller input to provide “active polarization control” (APC).

Abstract: A method and apparatus for polarization measurements. A polarization state of an optical signal can be determined using a polarization analyzer comprising a polarization controller, a polarizer, a wavelength dispersive element and a photo-detector. The method and apparatus can be applied to polarization and polarization mode dispersion measurements in wavelength division multiplexed communication systems.

Abstract: A fiber optic cable is disclosed that buffers against loss, where the cable includes an outer jacket, and an optical fiber ribbon disposed within the outer jacket, wherein the ribbon includes more than one optical fiber, and at least two distinct matrix coatings disposed on the optical fibers, the coatings having distinct characteristics. Preferably, the inner coating is relatively soft, with a lower elastic modulus than the relatively stiff, hard outer coating. Also disclosed is a method of buffering loss in an optical fiber transmission, including providing an optical fiber ribbon, wherein the ribbon includes more than one optical fiber, and at least two distinct matrix coatings disposed on the optical fibers, the coatings having distinct characteristics; and transmitting in at least one of the C-band, L-band and U-band of wavelengths.

Abstract: Systems and techniques are described for fabricating a low-loss, high-strength optical transmission line. In one described technique, a first fiber is spliced to a second fiber at a splice point. The spliced fibers are loaded into a heat treatment station, where a gas torch flame is used to thermally treat a splice region including the splice point, with the thermal treatment reducing splice loss between the first and second fibers. While heating the splice region, a dry gas is purged around the torch flame during the heat treatment process to avoid water at the surface of the spliced fibers. According to further described techniques, a purging gas is fed to the torch flame to purge dust particles from the flame, and after the heat treatment has been completed, the torch flame is used to restore the glass surface of the spliced fibers. Additionally described are torch assemblies for fabricating low-loss, high-strength optical fiber transmission lines.

Abstract: Adapter systems for dynamically updating information related to a network and methods for developing the adapter systems, are provided. An adapter system for dynamically updating information related to the network comprises: an adapter; and an antenna integrated in one of a surface of the adapter and in a tape overlay that can be affixed to the surface of the adapter. A method for developing an adapter system comprises: obtaining an adapter; and integrating an antenna in one of a surface of the adapter and in a tape overlay that can be affixed to the surface of the adapter.

Abstract: Single-mode optical fiber systems, incorporating fiber of core radius of sufficient size to support the fundamental mode together with from one to three higher order modes, exhibit performance/cost advantages relative to systems based on traditional single-mode fiber.