Abstract: Embodiments of the invention include a method and apparatus for making optical fiber preforms and optical fiber. The method includes the steps of positioning an overclad tube around a preform core rod, heating the overclad tube along the length thereof in the presence of a pressure gradient to collapse onto the preform core to form the overclad optical fiber preform, and adjusting the radial size of a heated portion of the preform core rod and/or the overclad tube to actively match the radial dimensions of the preform core rod along the length thereof with corresponding portions of the overclad tube. The active matching reduces variations in the physical dimensions of the preform core rod and/or the overclad tube, which improves transmission and other performance characteristics of fiber drawn from the created preform, e.g., by maintaining a relatively constant D/d ratio of the preform.

Abstract: Embodiments of the invention include an optical communication system having an optical cable with an improved configuration for multi-fiber arrangements. In particular, the invention is embodied in an optical communication system including an optical cable having an improved dry filling compound for protecting and maintaining multi-fiber arrangements therein and yet enabling relatively easy access thereto. The system includes a source of optical energy, an optical cable coupled to the source for transmitting optical energy from the source, and a receiver coupled to the optical cable for receiving optical energy from the source. The optical cable includes at least one multi-fiber unit tube having therein a plurality of optical fibers such as individual fibers or one or more fiber ribbons, and a dry filling compound formed around the at least one multi-fiber unit tube.

Abstract: Embodiments of the invention include an optical communications system with optical fiber cable, coupled between optical transmission and receiving devices, having positive dispersion fiber and corresponding inverse dispersion fiber. The inverse dispersion fiber includes a doped core region with an index of refraction n1, a cladding region with an index of refraction n2, and a trench region, a first barrier region and a second barrier region with indices of refraction n3, n4, and n5, respectively, formed between the doped core region and the cladding region. The various regions of the inverse dispersion fiber are manufactured in such a way that the refractive index value ranges are, e.g., 0.745%<(n1−n2)/n2<0.759%,−0.403%<(n3−n2)/n2<−0.394%, 0.152%<(n4−n2)/n2<0.166%, and −0.083%<(n5−n2)/n2<−0.041%.

Abstract: Embodiments of the invention include an optical fiber device such as a modulator, variable attenuator or tunable filter including an optical fiber having a core region, a cladding layer around the core region, and a controllable active material disposed in, e.g., capillaries or rings formed the cladding layer. The active materials include, e.g., electro-optic material, magneto-optic material, photorefractive material, thermo-optic material and/or materials such as laser dyes that provide tunable gain or loss. The application of, e.g., temperature, light or an electric or magnetic field varies optical properties of the active material, which, in turn, varies or affects the propagation properties of optical signals in the device. The optical device includes a tapered region that causes the core mode to spread into the cladding region and, simultaneously, allows the active material to be relatively close to the propagated modes, thus allowing interaction between the active material and the propagating modes.

Abstract: Embodiments of the invention include an optical communications system including a multimode optical fiber having improved overfill-launch bandwidth performance without disturbing existing laser-launch bandwidth performance. The multimode optical fiber has a characteristic differential mode delay with a first portion associated with lower order modes that behaves conventionally and a second portion associated with higher order modes that deviates from conventional behavior in a way that improves overfill-launch bandwidth performance at one operating window without adversely impacting the laser-launch bandwidth performance at the same and other operating windows. Multimode optical fibers conventionally optimized for operation at 850 nm are configured in such a way that their characteristic differential mode delay, at 1300 nm, initially increases in a conventional manner and then flattens out to approximately zero at the higher order modes.

Abstract: Embodiments of the invention include an optical communications system including one or more optical transmission devices, one or more optical receiving devices, and at least one positive dispersion optical fiber coupled therebetween. The fiber includes a doped core region with an index of refraction n1, a cladding region with an index of refraction n2, and first and second annular rings or regions therebetween with indices of refraction n3 and n4, respectively. The various regions are manufactured in such a way that the refractive index value ranges are: 0.14<(n1−n2)/n2<0.31, −0.19<(n3−n2)/n2<−0.02, and −0.20<(n4−n2)/n2<−0.08. The fibers exhibit a chromatic dispersion greater than 20±2.0 ps/(nm-km) and a dispersion slope less than 0.062 ps/(nm2-km) at a wavelength of 1550 nm. Also, the fibers have a relatively large effective core area, Aeff, e.g., greater than 100.0 &mgr;m2, and a relative dispersion slope (RDS) less than 0.0032 nm−1.

Abstract: Embodiments of the invention include a method and apparatus for making a multiple overclad optical fiber preform. The method includes positioning a first overclad tube around a preform core rod, positioning at least one second overclad tube around the first overclad tube, and collectively heating the preform core and the overclad tubes under pressure to collapse the overclad tubes onto the preform core rod thus producing a multiple overclad optical fiber preform. The apparatus includes a preform core rod, a first overclad tube surrounding the preform core rod, and at least one second overclad tube surrounding the first overclad tube. A quartz disc with or without one or more quartz spacers is used for supporting the preform core rod and the first overclad tube within the additional overclad tubes.

Abstract: Embodiments of the invention include an optical fiber minicord cable and a communication system employing the minicord cable. The optical fiber minicord cable includes a buffered optical fiber having a first strength layer formed around the buffered optical fiber, a first fire resistant jacket formed around the first strength layer, a second strength layer formed around the first fire resistant jacket, and a second fire resistant jacket formed around the second strength layer. The first and/or second fire resistant jackets are made of a fluoropolymer such as poly(vinylidene fluoride) (PVDF) or poly(vinyl chloride) (PVC), including PVDF Solef® 32008 and low smoke poly(vinyl chloride) (LSPVC) Apex® 910. The first and/or second strength layers are made of, e.g., polyaramid yarns such as Kevlar® and Nomex®. The buffered optical fibers typically have conventional structure, with the buffer region made of a suitable material such as nylon (e.g.

Abstract: Embodiments of the invention include an optical uniform spacing assembly for aligning a multipitch plurality of optical fibers into a uniform pitch linear array of optical fibers. The assembly includes an organizer body having a slot formed therein that extends longitudinally along the body. A portion of the slot has a width dimensioned to allow only one optical fiber at a time therethrough simultaneously and a depth dimensioned to align a multipitch plurality of optical fibers into a uniform pitch linear array of optical fibers. The assembly provides sufficient alignment for transitioning from, e.g., an optical fan-out arrangement such as a plurality of individual optical fibers to, e.g., an optical fan-in arrangement such as a ribbon cable arrangement. The assembly provides a compact, easily assembled apparatus and method for overcoming size mismatch and other conventional problems associated with transitioning between differing arrangements.

Abstract: Embodiments of the invention include an integrated circuit output buffer, with a pre-drive stage and an output driver stage, that provides linear performance independent of the load impedance. The output driver stage includes a pull-up resistor arrangement having a plurality of branches connected in parallel and, alternatively at least one pull-down resistor arrangement having a plurality of branches connected in parallel. The branches of the pull-up resistor arrangement include at least one resistor and at least one transistor serially connected between a supply voltage and the output buffer output terminal connectable to the PAD external to the output buffer. The transistor in the pull-up arrangement is connected to both the data terminals from the pre-drive stage and the control bit terminals.

Abstract: Embodiments of the invention include an optical fiber laser system with a cascaded Raman resonator (CRR) or other suitable Raman frequency shifting device having a length of optical fiber with at least one input pump reflector, a series of Raman-Stokes order reflectors and an output reflector therein. The reflectors are written to provide sufficient conversion efficiency despite the use of the cascaded Raman resonator with differing pump laser wavelengths. The reflectors are written not necessarily in correspondence with the gain maxima of the intermediate Stokes orders, but instead are written to reflect with less than maximum gain conversion intensity, yet in a manner that allows different pump laser wavelengths to be converted thereby. When operating the cascaded Raman resonators at sufficiently high pump powers, input pump reflectors are not necessary. Cascaded Raman resonators designed in accordance with embodiments of the invention are useful with different pump laser wavelengths.

Abstract: Embodiments of the invention include an optical energy transmission system, method and apparatus having improved mode coupling. According to embodiments of the invention, an optical energy transmission medium such as an optical fiber includes a plurality of particles formed in one or more coating region layers surrounding the cladding region and/or one or more buffer region layers surrounding the coating region for inducing microbending thereof, thus promoting advantageous mode coupling, which improves bandwidth potential by reducing dispersion. The method for manufacturing the inventive optical energy transmission medium includes forming one or more coating region layers and/or one or more buffer region layers containing particles such as fumed silica in such a way that particles are maintained within the optical energy transmission medium and form controlled perturbations along the optical fiber that enhance mode coupling to the extent that bandwidth of the optical fiber is improved.

Abstract: Embodiments of the invention include an optical energy transmission system, method and apparatus having improved mode coupling. According to embodiments of the invention, an optical energy transmission medium such as an optical fiber includes bubbles formed therein for inducing microbending of the optical energy transmission medium, thus promoting advantageous mode coupling, which improves bandwidth potential by reducing dispersion. The bubbles are formed, e.g., in one or more buffer region layers and/or at the interface between the coating and buffer regions. The method for manufacturing the inventive optical energy transmission medium includes controllably forming one or more buffer region layers around the coated optical fiber or other transmission medium in such a way that that a desired amount of bubbles is created and maintained within one or more of the buffer region layers and/or at the interface between the coating and buffer regions.

Abstract: Embodiments of the invention include an optical communications system including an apparatus and method for laterally displacing or otherwise steering optical signals passing therethrough. The system comprises a launching device for launching or transmitting an optical signal, a receiving device for receiving an optical signal, and at least one optical guiding element. The optical guiding element is a transmission medium that captures and transmits optical information therethrough and is configured, e.g., via end geometries, to redirect a portion of light propagating in a first direction and entering the first end substantially along its transmission axis and to redirect light propagating along the transmission axis out of the second end in a desired direction, e.g., a second direction laterally displaced from the first direction. Embodiments include angled faces with or without reflective coatings and attached lenses opposing the angled faces.

Abstract: Embodiments of the invention include a sensor such as a capacitive sensor with improved scratch resistance. The sensor has a substrate and a layer of sensing elements formed thereon that are formed from materials having a greater mechanical firmness than conventional aluminum or other soft metal materials. Sensor interconnects also are made of such materials. The increased mechanical firmness of the sensing elements and interconnects improves the scratch and mechanical resistance thereof by reducing scratches, mechanical stress and cracks by reducing the deformation and consequently the bridge and/or gap effects of the sensing element material. Such effects plague conventional electronic devices, integrated circuits and sensors. Alternatively, the inventive sensor includes, e.g., a dielectric region operably coupled to the sensing elements and interconnects, thus forming a capacitive sensor or other electronic devices.

Abstract: Embodiments of the invention include an optical fiber connector that supports a linear array or ribbon array of optical fibers. The connector includes a pair of intermatable housing members that, when mated, define a connector having a front end suitable for butt coupling to other connectors or compatible connections, a back end for terminating an array of optical fibers, and a plurality of waveguides or optical fiber support grooves extending from the front end to the back end. According to embodiments of the invention, the back end has at least one feature that increases the opening formed by the housing members at the back end of the connector, thus making it easier to terminate an optical fiber or array of optical fibers therein that optically couples to the waveguide or optical fibers terminated in the front end. For example, one or both housing members include a beveled or curvelinear portion, both of which increase the opening between the housing members at the back end of the connector.

Abstract: Embodiments of the invention include an improved diamond-based surface acoustic wave (SAW) filter device. The SAW device comprises polished, large-grained diamond in combination with a piezoelectric layer to enhance the acoustic velocity and operational frequency of the SAW device with reduced loss and increased efficiency. Also, the use of a pre-polished, large-grained diamond slab reduces processing complications such as contamination or stressing of delicate device circuitry adjacent to the diamond component. Alternative embodiments of the invention include planar or vertical interconnection schemes for packaging of the SAW device and also include planarization schemes for convenient deposition and patterning of the SAW device metallization layer.

Abstract: A method for controlling a bore diameter of an optical fiber ferrule is disclosed. The diameter of the bore is controlled by collapsing the ferrule around a rod inserted in an over-sized bore formed therein. The diameter of the rod is selected to match the diameter of the optical fiber to be supported by the ferrule. Thus, after the rod is subsequently immersed in liquid nitrogen removed from the ferrule, the ferrule has a bore diameter which is defined by the diameter of the rod. Suitable materials for the ferrule and the rod include glass and metal, respectively.

Abstract: Embodiments of the invention include an amplifier such as a differential amplifier having an improved common mode voltage range (CMVR). The amplifier includes a translator coupled to a second stage amplifying circuitry wherein the translator uses feedback and a parallel connection of input devices to improve the common mode voltage range of the amplifier while providing for enablement of the circuit functionality. The translator uses parallel connections of N-channel and P-channel devices such as transistors to extract alternating current (ac) signals riding on a common mode voltage and to translate the extracted ac signals to ride on a constant reference voltage (V.sub.ref). The translated signals are then amplified in a conventional manner, such as by a gate thresholding or a self-biasing technique. An input sensing circuit within the translator provides an offset detection signal to a correction circuit, also within the translator.

Abstract: Embodiments of the invention include a method and apparatus for modulating data retrieved from page-wise memory systems such as holographic memory systems. The inventive method uses the detection of one or more test signals included within stored data image pages to estimate the behavior of the retrieved data image pages and to normalize the retrieved information accordingly. The method includes allocating a portion of the data image pages of interest for one or more determinable test signals and incorporating the test signal information into the data image pages prior to storage of the data image pages within the storage medium. Upon retrieval of the data image pages from the storage medium, the test signals are detected and used to form the basis of estimated data member behavior across individual data image pages and, alternatively, from one data image page to another. Based on the estimated behavior, appropriate normalization is performed on the data image pages.