Abstract: An improved optical isolator having a pre-aligned first and second collimator and a pre-aligned core assembly joined with the first collimator, the first and second collimators and core assembly all disposed within a housing tube. The core assembly is aligned with and joined directly to the first collimator and fits snugly within the housing tube. The second collimator fits within the housing tube such that it can be aligned with core assembly to minimize insertion loss. The first and second collimators are connected to the housing tube by solder joints, at least one of which is made from a low temperature solder. The core assembly includes a cylindrical permanent magnet, a pair of birefringent wedges and an optical rotator. The optical rotator is joined to a wedge on either side and the combined structure is affixed to the cylindrical permanent magnet.

Abstract: The invention relates to a method and a modulator circuit for modulating light in a modulator circuit. The modulator circuit comprises a Mach-Zehnder modulator having at least one optical input and at least one optical output, said Mach-Zehnder modulator modulating light, which is fed to the input of the Mach-Zehnder modulator in response to applied electrical modulation signals from a driver circuit. According to a method of the invention, the applied modulation signal on the electrodes of the Mach-Zehnder modulator is superimposed by a pilot tone which is thus superimposed by the modulated light emitted by the Mach-Zehnder modulator. In response to the emitted modulated light, an electrical feedback circuit generates bias control signals for the bias circuit and driver control signals for the driver circuit for regulating the bias signal and the driver signal fed to the Mach-Zehnder modulator.

Abstract: An assembly for providing thermal compensation to a fiber optical device is described. The optical fiber device is secured in a support structure made of a material having a negative coefficient of thermal expansion. The securing means located at on end of the support structure is made of a material having a positive coefficient of thermal expansion. The securing means is also adjustable lengthwise so as to provide longitudinal adjustment to the tension on the optical fiber device. By selecting the appropriate materials and dimensions the assembly can exactly compensate for the thermal dependency of the optical device with an overall length much smaller than assemblies based on materials with dissimilar positive CTEs.

Abstract: An improved method for providing high-quality optical fiber metallization with the required length at the required location. The method enables metallized optical fibers to be soldered and connected to mechanical components while reducing the level of stress in the metal coatings and providing strong adhesion, good conductivity and connectivity. The advantage of the method is a combination of vacuum evaporation and electroless deposition for the optical fiber metallization. A strong adhesion of the metal layer is achieved by the use of an evaporated thin metal layer, comprising an adhesion layer and a seed layer. The stress reduction is achieved due to electroless deposition, which is adequately thick for subsequent soldering/welding or other applications. The method comprises preparation for evaporation, preparation of optical fibers, evaporation of the thin metal adhesion and seed layer on the optical fiber, electroless deposition of an adequately thick metal layer, and acceptance testing.

Abstract: Coupler packages for providing protection against the elements for fused fiber couplings. The coupler package has an inner and outer cylinder for providing additional buffering against vibration, temperature expansion, corrosion, and water penetration. The double tube structure increases the penetration length for water, while the seals decrease the cross section for water penetration.

Abstract: A multiple-port optical device combines two polarization combiner-splitters into one package. Two single mode optical fibers are enclosed in a first ferrule of the package and are optically coupled to four polarization maintaining fibers enclosed in a second ferrule of the package. The optical fibers are precisely positioned using improved fiber ferrules comprising various capillary designs. A prism is mounted between the single mode fibers and the polarization maintaining fibers. The fibers are screened for geometric characteristics which aide in precisely positioning the fiber cores. The ferrules, capillaries, fibers, and adhesives are combined to reduce adverse thermal effects over a broad range of environmental conditions. The precise positioning and geometry of the optical fibers aids in optically aligning the elements of both polarization combiner-splitters in the one package. The invention is applicable to related devices such as multiple isolators, combiner-isolators, splitter-isolators, and the like.

Abstract: A dispersion and dispersion slope compensating optical fiber includes a segmented core and a cladding layer wherein the refractive index profile is selected to provide a dispersion having a maximum deviation of less than 7 ps/nm-km over a wavelength band from 1550 nm to 1610 nm. According to a further embodiment of the invention, a dispersion compensating optical fiber is provided having a refractive index profile with a central core segment having a positive relative refractive index; a depressed moat segment on a periphery of the central core segment having a relative refractive index that is more negative than −1.2%; and an annular ring segment outward from the depressed moat segment having a relative refractive index that is greater than 1.2%.

Abstract: A fiber-optic cable includes a conductive coating formed around an optical fiber. The conductive coating may be in the shape of a band or ring located at a terminal end of the fiber, or may extend along the entire length of the fiber or a portion thereof. For protection purposes, the fiber is covered with a buffer made from a plastic or polymer. The fiber-optic cable may be attached to a plug or receptacle of a connector. Preferably, the cable is attached to the plug. Under these circumstances, the receptacle would be equipped with a verification circuit for confirming that the plug has been properly installed into the receptacle housing. An electronic device may be used to alert a user as to whether proper installation has occurred. In addition to providing an indication that an optical connection has been made, the conductive coating may be adapted to carry electrical signals. In this way, the fiber-optic cable would operate as an electrical transmission line and an optical transmission line.

Abstract: A method of splicing optical fibers is provided to reduce the splicing loss of the first and second optical fibers having different MFDs from each other. In a pre-fusion heating step, the MFD at the adjacent end face of the optical fiber having larger MFD is enlarged by heating a portion including the adjacent end face thereof so as to diffuse a dopant. After the pre-fusion heating step, fusion-splicing of the first and the second optical fibers is performed. Thereafter, during the post-fusion heating step, the dopant is diffused by heating a portion including the fusion-spliced part between the first and the second optical fibers.

Abstract: A higher order mode generator includes a straight waveguide having upper and lower cladding layers and a core layer which support higher order modes higher than the 0th order. A linear heater is disposed across the waveguide at a tilt angle &agr; with respect to the waveguide. For converting the 0th order optical guiding mode into the mth order optical guiding mode, a tilt angle &agr; of the linear heater and the mth order mode propagation angle &thgr;m satisfy the condition: &agr;>&thgr;m/2.

Abstract: An optical module for an optical device and an optical fiber is constituted by a pre-molded plastic package. In forming the plastic package, the main flowing direction of the molding resin is substantially parallel with the optical axis of the optical fiber. The optical module is formed by molding the resin by injection using pressure and then solidifying the resin. When the plastic package is formed by comprehensive molding, the flowing direction of the resin is parallel with the optical axis direction of the optical fiber to be installed in the optical module. As a result, for comprehensive molding, the molding pressure applied to the optical fiber is reduced. By using the resin case that is formed, the resulting package exhibits high rigidity and low thermal expansion properties in connection with the flowing direction of the resin, thus reducing the external stress and thermal stress applied to the optical fiber.

Abstract: An optical cable has a reduced slicing loss and superior characteristics in the efficiency of the installation work thereof, and is therefore suitable for installation on land. First and second optical fibers have been connected together by fusion splicing to form joints thereby providing an optical fiber line. Each first optical fiber has a positive chromatic dispersion at a signal light wavelength while each second optical fiber has a negative chromatic dispersion at the same wavelength. The first and the second optical fibers, including the joints, are accommodated in the optical cable.

Abstract: An apparatus which holds an optical fiber in alignment to an optical device includes a fiber holder having a first plurality of indentations, an optical fiber held within one of the first plurality of indentations, a base substrate having a second plurality of indentations formed in a top surface of the base, a plurality of spacers, each of the plurality of spacers held within one of the second plurality of indentations and an optical device mounted on the base. The fiber holder is mounted on the base with the plurality of spacers within the first plurality of indentations.

Abstract: An optical filter is produced that has a desired spectral response. This is done by first decomposing the desired spectral response into individual simulated responses (F1 . . . F4) using a suitable computer program. Then tapered fiber filters are manufactured with parameters that closely match the individual responses. And finally the tapered fiber filters are concatenated on a single-mode fiber to produce the optical filter with a total response that closely matches the desired spectral response.

Abstract: An optical CDMA encoder-decoder is constructed by combining arrayed-waveguide gratings, matrix optical switches, and delay lines, otherwise by combining arrayed-waveguide grating and variable delay lines, thus providing an encoding process that a wavelength change with respect to time in optical pulses. The light includes a wide spectrum band width inserted into a CDMA encoder/decoder and is demultiplexed by arrayed-waveguide gratings. Each wave length according to the demultiplexed spectrum component spreads out in the time region based on delay time differences produced by delay lines having differential optical lengths. Thus, in CDMA, the dependency of wavelengths on delay time can be set arbitrarily.

Abstract: The packaging architecture for a multiple array transceiver using a flexible cable of the present invention provides a 90-degree transition between an optical signal input at a communications chassis bulkhead and an interior board within the communications chassis. The packaging architecture system comprises a forward vertical carrier having an optical converter, a paddle card, a flexible cable operably connected between the forward vertical carrier and the paddle card, and a rearward horizontal I/O block operably connected to the paddle card, the rearward horizontal I/O block oriented about 90 degrees from the forward vertical carrier. The multiple array transceiver makes the 90-degree transition within a narrow gap established by industry and manufacturer standards. The multiple array transceiver further provides cooling through a heat sink.

Abstract: An optoelectronic gas sensor based on optodes, where multiple separate photosensitive elements and an opto-transmitter located centrally between them are integrated into or onto a semiconductor substrate is characterized in that the photosensitive elements lie in one plane in the substrate, and together with a lateral emission area of the opto-transmitter emitting light laterally, they are covered by sections of the optode material whose thickness and refractive index are selected so that light emitted laterally from the emission area is guided to the photosensitive elements by total reflection in the optode material in each transmission branch. Such a chip-shaped gas sensor based on optodes can be implemented in a very small design, e.g., in an area of 2×2 mm2 and a thickness of 250 &mgr;m.

Abstract: The present invention provides an optoelectronic device, a method of manufacture therefore, or an optical communications system including the optoelectronic device. The optoelectronic device may include a substrate and a waveguide located within the substrate. Additionally, the waveguide may include a first portion having a width, depth, and refractive index, and a second portion having a different width, depth and refractive index.

Abstract: Chemically specific fiber and waveguide sensors are formed in a fiber optic or optical waveguide material in which injected light is trapped within a Bragg grating optical cavity. The Bragg cavity effectively traps the light for long times, corresponding to effective path lengths equal to hundreds or thousands of meters in the fiber or waveguide medium. The Bragg grating optical cavity is surrounded by a cladding of chemically sensitive material whose optical properties change when exposed to specific chemicals or classes of chemicals. The change in the optical properties of the cladding results in a change in the light trapping characteristics of the fiber or waveguide. Changes in optical transmission of the fiber optic or waveguide sensor can then be related to the concentration of specific chemicals or classes of chemicals in the environment surrounding the sensor.

Abstract: An apparatus and method for thermally tuning an optical amplifier comprises an optical waveguide doped with a fluorescent material, a thermal device for either heating or cooling the optical waveguide, and a pump light for exciting the fluorescent material. The apparatus shapes, shifts, and/or flattens the gain curves of the doped optical amplifier. Thulium doped fiber is cooled to shift the gain curve into the C-band. Erbium doped fiber is heated to flatten the gain curve in the C-band and is cooled to shift the gain curve above the L-band. The apparatus similarly shapes the gain curves of other fluorescent materials. The thermal device comprises three types of optical cooling devices. The apparatus is a component in communications systems, lasers, medical lasers and the like. The method comprises either heating or cooling optical waveguides doped with fluorescent materials to achieve the desired shaping, shifting, and flattening of the gain curves.