Abstract: A switch is provided that includes three stages. The first stages has a plurality of switch circuits. The second stage has a plurality of switch circuits equal to N, where N is any integer other than a power of 2 and where the switch circuits can be logically configured into a logical configuration of a power of 2. The third stages includes a plurality of switch circuits.

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: Control of an interconnection process for optical fibers involves evaluating the status of all modules used in the process and moving an optical fiber through the process in accordance with the status of the modules. Such control allows more than one fiber, and more than one fiber type, to be processed simultaneously. The processing may be optimized using fuzzy logic to track when operations performed by a module are near completion. A graphical user interface displaying the movement of the optical fibers through the process may also be provided.

Abstract: In accordance with the present invention, an optical device is provided which selects narrowly spaced optical channels used in dense wavelength division multiplexed systems. The device includes a first and second Bragg gratings in a cascaded configuration where each grating has a length which is shorter than a single grating configured to select a channel within a narrowly spaced channel plan. When taken together, the two Bragg gratings provide a narrow bandwidth wavelength selection device for narrowly spaced optical channels while avoiding manufacturing drawbacks associated with writing long gratings.

Abstract: The invention was originally developed to determine the strain-relief capability of a fusion splice protector as well as the compressive stress imparted to a fusion splice by the splice protector. The invention also permits performance and comparative analyses of splice protectors as well as any package in which the optical fiber is at least partially disposed. To those ends a fiber Bragg grating (FBG) is axially arranged relative to the package such that a free or reference section of the FBG protrudes from the package while a shielded section lies within the package. Broadband light is supplied to the FBG which reflects certain wavelengths that are measured by an optical spectrum analyzer. The FBG reflected spectra will be split into two peaks as the reference and shielded sections experience different amounts or types of stress thereby providing a powerful analysis tool.

Abstract: A simple and cost effective optical device is provided which locks the wavelength output of a laser transmitter in an optical transmission system as well as substantially reducing and/or eliminating signal crosstalk. A light source is coupled along an optical path to a filtering element. The light source has output frequency shifts based on variation in input current. The filtering element is configured with a reflectivity characteristic which corresponds to a first portion of the optical signal associated with one or more frequencies such that the reflectivity characteristic is greater than the output frequency variations associated with the light source.

Abstract: A system prevents damage to at least one component of a laser apparatus that includes a laser that emits a light signal of increasing power during power up and at least one connector that receives the light signal from the laser and reflects at least a portion of the light signal when an imperfect connection exists. The system includes a detector and a monitoring circuit. The detector detects the reflected light signal from the connector. The monitoring circuit receives the reflected light signal, determines an amount of power in the reflected light signal, calculates a ratio of the power of the light signal emitted by the laser to the power in the reflected light signal, compares the ratio to a predetermined threshold to determine whether the imperfect connection exists, and shuts down the laser when the imperfect connection exists.

Abstract: In the disclosed error correcting scheme, information data is encoded and decoded in parallel and in the spectral or frequency domains based on a Reed-Solomon (RS) code. As a result, when compared with space domain decoding, the spectral decoding scheme of the present invention shifts some of the computationally intensive modules into the encoder thus reducing decoder complexity. Thus, integrated circuit implementations of the error correcting scheme of the present invention are faster, have reduced power dissipation and occupy less chip area than serial encoders and decoders.

Abstract: An optical interference filter having high transmissivity at first and second passbands. The interference filter includes a first stack having a plurality of dielectric layers, a second stack having a plurality of dielectric layers, and a spacer interposed between the first and second stacks. Each of the dielectric layers included in the first and second stacks have optical thicknesses which vary quadratically. The dielectric layers have alternating high and low refractive indices.

Abstract: In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demutiplexer, the interference filters and sub-demultiplexer create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1×n splitter. Accordingly, large numbers of channels, e. g., in excess of forty can be readily demultiplexed and detected.

Abstract: An optical filter including a plurality of dielectric layers is provided on a quartz substrate. Quartz is advantageous as a substrate material because it has relatively low loss at wavelengths commonly used in telecommunication systems. Moreover, it is thermally and chemically stable, and has good adhesion to most dielectric films used as quarter and half wave layers. Further, quartz is mechanically tough, relatively inexpensive and readily available. The quartz substrate is cut from a crystal and has an orientation with reduced birefringence. In addition, the thickness of the quartz substrate is selected to reduce temperature-related shifts in the center wavelength of the filter.

Abstract: A WDM system carrying a plurality of optical signals, each at a respective wavelength, is provided whereby each optical signal includes a plurality of frames, each frame conforming to a synchronous optical network (SONET) standard. A plurality of optical transmitter modules output a corresponding one of the plurality of optical signals, and each of a plurality of optical selector at a receiving end of the WDM system selects a respective one of the plurality of optical signals. In addition, a plurality of receiver modules are provided respectively connected to each of the optical selectors. Both the transmitter and receiver modules include byte extraction circuitry that extracts one byte, e.g., the J0 byte, from each of the plurality of frames. Successive bytes are grouped as messages, which are stored in registers so that comparisons can be made between consecutive messages and a predetermined message.

Abstract: In accordance with the present invention, a dispersion compensation module is coupled to a transmission optical fiber. The dispersion compensation module includes segments of optical fiber of varying length, some of which have a positive dispersion while other have a negative dispersion. Selected optical fiber segments are coupled to one another to provide a desired net dispersion to offset the dispersion associated with the transmission optical fiber. Thus, rather than provide a unique segment of DCF for each span, the same dispersion compensation module can be used for spans of varying length and fiber types by simply connecting appropriate segments of fiber within the module.

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.

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 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: The present invention provides a remodulating channel selector for a wavelength division multiplexed optical communication system. The remodulating selector receives a WDM input signal, selects a particular optical channel from the WDM signal and places the information from the selected signal onto a newly-generated optical output signal. The wavelength of the output optical signal can be the same as or different from one of the optical channels which comprises the WDM input signal. When used in a WDM optical communication system with remodulators at the transmission input, the remodulating selectors provide complete control over the interfaces with optical transmitters and receivers, permitting use with a broad range of optical equipment.

Abstract: An optical device is provided which locks the wavelength output of a laser transmitter in an optical transmission system as well as preventing the propagation of unwanted signals generated by the laser transmitter prior to the transmitter reaching the desired operating wavelength thereby reducing crosstalk between channels within a wavelength division multiplexed communication system.

Abstract: To take advantage of 56K modem technology, a data signal must only traverse one digital to analog (D/A) conversion and one analog to digital (A/D) conversion on the return path to a subscriber. However, current data transmission for subscribers served by a Universal DLC system requires a D/A conversion at a voice switch of a public switched telephone network (PSTN), an A/D conversion at the central office terminal of a PSTN and a D/A conversion at a remote data terminal of a DLC system. This adds a D/A and an A/D conversion which causes 56K modem technology to fail. The present invention provides a telephone call routing apparatus installed between subscribers served by a Universal type digital loop carrier system, a central office terminal of a PSTN and a data network interface.

Abstract: An optical filter having broad resonant frequency passbands for filtering an optical input including a plurality of multiplexed optical wavelengths into a first set of transmitted wavelengths and a second set of reflected wavelenghts. The filter has first and second inner mirrors separated substantially by an inner spacer, a first outer mirror separated from the first inner mirror substantially by a first outer spacer, and a second outer mirror separated from the second inner mirror substantially by a second outer spacer. The inner mirrors have reflectivity which is greater than the reflectivity of the outer mirrors, and are formed from layers of alternating high and low refractive index materials. The optical thicknesses of the spacers are substantially identical, and are sized to align the resonant frequency passbands of the filter with the first set of transmitted wavelengths.