Abstract: An add/drop multiplexer includes first and second fiber grating connected to a four-port optical circulator having first and second input/output ports, an add port, and a drop port, wherein the first fiber grating is connected to the first input/output port and the second fiber grating is connected to the second input/output port. Add signals provided to the add port of the circulator are reflected by the first fiber grating back to the optical circulator and propagate, along with one or more input optical signals, to the second fiber grating. One or more of the input optical signals are reflected by the second fiber grating back to the optical circulator and propagate to the drop port of the circulator.

Abstract: An optical amplifier is provided in which optical channels, each at a respective wavelength, make two passes through a segment of erbium-doped optical fiber. After the first pass, certain optical wavelengths lying in the high gain spectrum (“the high gain wavelengths”) of the erbium-doped optical fiber are amplified more than other optical wavelengths lying in the low gain spectrum (“the low gain wavelengths”). The optical channels are then reflected with a reflective element back to the segment of erbium-doped optical fiber for the second pass. The reflective element selectively attenuates the high gain wavelengths to compensate for the excessive gain of the erbium-doped optical fiber at these wavelengths. As a result, after the second pass, the optical power at the high and low gain wavelengths is substantially the same and gain flattening is achieved.

Abstract: A WDM ring configuration having a central office node is provided in which each channel has substantially the same loss and no single channel has a disproportionately high loss. Thus, the diameter of the WDM ring in accordance with the present invention can be increased and/or the number of filters provided along the ring can be increased to accommodate additional channels.

Abstract: A workstation for use in the assembly of component parts includes a computer terminal having a display and at least one input device, a test apparatus operatively coupled to the computer terminal, and an application program which generates a first display screen for display of an assembly procedure to be followed by an assembler on the display of the computer terminal and a second display screen for display of test results obtained by the test apparatus on said display of said computer terminal. In the case where at least one of multiple assembly steps includes a test function, the application program automatically performs the test function using the test equipment and inhibits display of a next assembly step in the event that results of the test function are outside predetermined parameters.

Abstract: The present invention provides add-drop multiplexers which are compatible with dense wavelength division multiplexed (WDM) systems having large numbers of optical channels. The add-drop multiplexers employ sets of Bragg gratings separated by an optical isolator to reliably add or drop optical channels without crosstalk. The Bragg grating sets and the optical isolator are interposed between first and second optical couplers. Optical channels to be dropped from a WDM optical signal are reflected by the first set of Bragg gratings and exit the add-drop multiplexer through the first coupler. Optical channels to be added to a WDM optical signal enter the add-drop multiplexer through the second optical coupler.

Abstract: A dispersion compensating element, such as a dispersion compensating fiber, is provided between two erbium doped fiber segments of a two stage amplifier, and is pumped with light of a sufficient wavelength and intensity to yield Raman amplification within the dispersion compensating fiber. As a result, optical loss of the dispersion compensating fiber is reduced and the overall noise figure of the amplifier is improved.

Abstract: A vision system is provided which allows viewing and/or inspection of an end surface of an optical fiber through a bulkhead on a backplane of a rack. By placing such a vision system on a mount configured to be inserted in the rack, the use of such a vision system does not require the rack design be modified or that other modules be removed. Preferably an adapter for mating the vision system with the bulkhead may be moved to position the adapter relative to the bulkhead housing the fiber of interest.

Abstract: A communications system includes a plurality of work stations and a relational database operatively linked therewith. Each of the workstations includes a computer terminal having a display and at least one input device, test apparatus operatively coupled to said computer terminal, and an assembly application program which generates a first display of an assembly procedure to be followed by an assembler on said display of said computer terminal and a second display screen for display of test results obtained by said test apparatus on said display of said computer terminal. The relational database stores data which is independent of the assembly program and which indicative of the assembly procedure used by the assembly application program. A data structure of the relational database includes an tracking table and an action table, in which the tracking table being used to link to data contained in the action table.

Abstract: The present invention is directed toward a distributed intelligence fiber-optic communication network in which node control processors (NCPs) associated with each network element periodically transmit identification and status information to the other NCPs in the network. Various faults in the network can thus be readily identified, and appropriate tasks for modifying the network in response to the fault (such as rerouting around a defective network element) can be carried out. Further, information continues to be distributed among the NCPs even if a break occurs in a segment of fiber in the network.

Abstract: An optical fiber alignment apparatus for leveling respective distal ends of a plurality of optical fibers prior to commencing a polishing process. The apparatus includes an aligning device having a plurality of receptacles for securing the corresponding plurality of optical fibers such that distal ends of the optical fibers extend below the base of the aligning device. A sensor array contacts the distal ends of the optical fibers and generates sensor alignment signals indicating the position of the fiber distal ends extending below the aligning device relative to a horizontal reference plane. A monitor receives and displays digital signals corresponding to the sensor alignments signals. Those optical fibers that are not aligned are then adjusted to until all the fibers are aligned and leveled with respect to the horizontal reference plane as viewed on the monitor.

Abstract: A optical device is provided for reducing coherent crosstalk associated with a particular channel within a communications network. An attenuator is coupled between an emitter associated with a first node and a receiving element associated with a second node. The attenuator adjusts the signal power level generated by the emitter such that the signal power is within the dynamic range of the receiving element.

Abstract: A method for monitoring a plurality of components associated with a communications network node. A diagnostic service signal is generated at an intra-node component and transmitted along a first optical path to another intra-node component where the presence or absence of the signal is detected. In this manner, optical paths defined between intra-nodal components can be monitored using a diagnostic service signal.

Abstract: An optical assembly workstation includes a principal work surface and a movable work surface arranged above the principal work surface, with the elevated work surface being movable back and forth in at least one axial direction relative to the principal work surface. A frame assembly provides both support and a mechanism for moving the elevated work surface relative to the principal work surface. The movable work surface is either configured to receive an optical work piece, or is itself the optical work piece. The arrangement of a movable work surface over the principal work surface provides flexibility in optical test and optical assembly equipment placement, frees the principal work surface area of clutter, and reduces the probability of inadvertent damage to the optical fibers and optical assemblies being manufactured or tested at the optical assembly workstation.

Abstract: In accordance with the present invention, an optical device is provided which is used to lock the output of an optical transmitter as well as being employed as a self-filtering element within an optical system. An optical transfer element, coupled along the optical transmission path, either reflects or transmits a portion of the light signal associated with the desired channel wavelength. A portion of the optical signal is supplied to a circuit which controls the output of the transmitter.

Abstract: An optical module inspection circuit on an optical platform includes an optical module carrier for precisely aligning optical devices with optical interfaces of inspection equipment located at fixed positions in the optical module inspection circuit. The module includes an apparatus for conveyance along a top surface of the optical platform. The module may be conveyed automatically to predetermined positions on the optical platform to automate alignment and positioning of optical devices with respect to optical inspection stations in the optical test circuit.

Abstract: In accordance with the present invention, an in-line fiber Bragg grating is coupled to the output of a directly modulated DFB laser. The grating preferably rejects chirp induced frequencies of light emitted by the DFB laser. Accordingly, light transmitted through the grating is spectrally narrowed and has a higher extinction ratio, thereby decreasing bit error rate probabilities.

Abstract: The present invention provides a wavelength division multiplexed optical communication system with dynamically stabilized wavelength selectors. To accurately correlate the wavelength of a wavelength selector to the wavelength emitted by an optical transmission source, the present invention uses an optical detector and feedback loop to optimize the wavelength of an optical selection element in accordance with a wavelength of an incident optical channel. In one embodiment, the optical selection element is a Bragg grating associated with a grating wavelength controller, such as a temperature regulator or strain tuning system, to adjust the wavelength band of maximum reflectivity of the grating. The feedback loop communicates with the optical detector and the wavelength controller to modify the grating's reflection wavelength band in accordance with the wavelength of an incident optical channel.

Abstract: A polishing apparatus for polishing optical fibers includes a polishing pad and a polishing arm arranged above the polishing pad and which is selectively brought into contact with the polishing pad. A leveling device is magnetically attached to a lower end of the polishing arm. The leveling device has a plurality of optical fiber ends extending downwardly from a lower surface thereof to contact the polishing pad. The polishing arm also contains a pressure transducer for measuring a pressure applied by the polishing arm when the polishing arm contacts the polishing pad. The magnetic attachment between the polishing arm and leveling device may be carried out using a permanent magnet or electromagnet.

Abstract: The component parts for assembly of a device, such as the passive optical components of an optical amplifier, are automatically selected from among a supply of available component parts. Each component part has a performance parameter such as insertion loss associated therewith. Stored in a database memory are component part data for each component part of the supply of available component parts. The component part data are in a computer readable format and indicative of a type of each part and the performance parameter of each part. To obtain the selection of parts of the device for assembly, the component part data for a plurality of the available component parts is retrieved from the database, and the thus retrieved plurality of component part data are sorted according to at least the performance parameter of each retrieved component part data. At least one component part among the sorted component part data is selected based on a preset parameter.

Abstract: The present invention provides a modulation format adjusting optical transponder for receiving an incident optical signal of a first modulation format and outputting an optical signal having a different modulation format. The transponder includes an optical-to-electrical conversion element configured to receive an information-bearing optical signal having a first modulation format and output an electrical signal corresponding to information from the incident optical signal. The transponder includes a laser for outputting an optical carrier signal at a selected wavelength and a modulator communicating with the optical-to-electrical conversion element and with the laser. The modulator places the information from the incident optical signal onto the optical signal output by the laser, creating a modulated optical output signal having a second modulation format different from the first modulation format.