Abstract: An optical power distribution system and method permits multiple power consuming devices to be selectively supplied with power using a single fiber optic line. In a described embodiment, multiple electrical power consuming well tools are interconnected to a fiber optic line extending into a well. Control modules are interconnected between the fiber optic line and the well tools. When a particular optical wavelength band is transmitted through the fiber optic line, a corresponding one of the control modules causes the respective well tool to be selected for electrical power to be supplied thereto.

Abstract: Disclosed is a multi-wavelength locking method for a wavelength division multiplexing (WDM) optical communication network, and in particular, a multi-wavelength locking method and apparatus for a WDM optical communication system that can lock wavelengths of optical signals by producing pilot tones by applying a sine-wave current to a plurality of transmission lasers having different wavelengths, passing the optical signal through a Fabry-Perot etalon filter, and then Fourier-transforming the filtered optical signal.

Abstract: An optical communication system includes a plurality of optical add/drop multiplexers (OADMs). The plurality of OADMs includes at least five low distortion OADMs. Each OADM is coupled between spans of a multiple span communication link and operable to receive a multiple wavelength signal. The multiple wavelength signal includes a plurality of bands of wavelength signals each separated from other bands of wavelength signals by one or more guard-channels. In one embodiment, each of the at least five low distortion OADMs adds/drops a common first band of wavelengths to/from the multiple wavelength signal. In some embodiments, a spectral distortion associated with a pass-through wavelength signal spectrally adjacent to one of the one or more guard-channels is no more than three decibels after exiting the last of the plurality of low distortion OADMs. In those embodiments, the guard-channel is adjacent to the first band of wavelengths.

Abstract: A new architecture is proposed for making optical cross connect in wavelength division multiplexed networks. The value of optical networks incorporating all-optical cross connects is typically associated with being able to selectively route individual channel wavelengths through several network nodes without performing optical-electrical and electrical-optical conversion. From a network perspective, most work on the optical cross connect architectures have been concentrated on the highest possible capability for the cross-connect itself. The problem with considering optical cross connect architectures in isolation without attention to the rest of the network may lead to unnecessarily complicated hardware. In the proposed architecture, architecture considers the network as a whole and significant cost reductions as well as complexity reductions are realized.

Abstract: A miniature WDM add/drop multiplexer and its manufacture is described. The device has a plurality of wavelength-dependent filters in the form of thin-film filters mounted to a core frame with the end sections of the input/output optical fiber and other optical fibers associated with each of the filters. The stresses associated with the filters are accounted for. The core frame is sealed, together with the overall package assembly, to provide for long-term reliability of the device. The described device and method of manufacture is also generally applicable to WDM multiplexers and demultiplexers.

Abstract: A method and apparatus for assigning channel bands to a wavelength division multiplexed (WDM) system is disclosed. The WDM system includes an arrangement of optical amplifiers, banded optical add-drop multiplexers (OADMs) having blocking filters, and a tunable edge filter. The channel band assignment method suppresses amplified stimulated emissions (ASE) in a partially populated system in which at least one of the blocking filters is not in the transmission path. Channel bands are assigned from one edge of an amplified transmission window to the other in a sequential order and the tunable edge filter is adjusted to attenuate ASE wavelengths not blocked by the blocking filters as channels are assigned. A channel decommissioning method is also disclosed which employs similar techniques and the tunable edge filter to suppress ASE as blocking filters are removed or otherwise deselected from the transmission path.

Abstract: The WDM receiver includes a wavelength demultiplexer, a detector array and a signal extractor. The wavelength demultiplexer receives an n-channel optical input signal and transmits the n-channel optical input signal to m optical outputs. Each of the optical outputs receives a wavelength band centered at a different wavelength. The wavelength bands have a center-to-center wavelength spacing of ???. The detector array is composed of m detector elements coupled to the wavelength demultiplexer. Each of the detector elements generates a detection signal in response to light received from one of the optical outputs of the wavelength demultiplexer. The signal extractor receives the detection signals from the detector array and converts the detection signals to an n-channel receiver output signal, each channel of which corresponds to a different one of the n channels of the optical input signal.

Abstract: Disclosed is an interleaver for an optical communication system. A dual collimator is combined with a first optical fiber acting as a light input port and one end of a second optical fiber spaced from the first optical fiber, and switches light advancing along the first and second optical fibers into parallel light. A beam splitter is arranged so that one surface is opposite to the dual collimator, and transmits one half of an input light and reflects the other half of the input light. A single collimator is arranged opposite to the other surface of the beam splitter, and combined with the other end of the second optical fiber so as to switch light advancing toward the other end of the second optical fiber into parallel light. An output optical fiber is arranged opposite to the other surface of the beam splitter and acts as a light output port.

Abstract: A wavelength division multiplexed (WDM) apparatus is provided for a bidirectional dense WDM optical fiber communication network with cost-effective and efficient allocation of the resources available at each network node. For each fiber link, the invention uses a WDM signal composed of channels propagating in opposite directions and a band optical add-drop multiplexer (OADM) to isolate or combine a band to the WDM signal spectrum. As a result, the invention significantly reduces the number fiber connections and filtering equipment required with respect to each direction of transmission.

Abstract: A diffraction-compensated WDM (wavelength division multiplexer) uses TTFs (thin film filters) as concave mirrors. The WDM has a plurality of filter elements for guiding the optical signal along a predetermined optical path, each filter element being transparent to a predetermined wavelength range and including compensating means for at least partially compensating for diffraction of the optical signal. Each filter element has a thin film coated on a substrate, and the compensating means is a curved surface of each thin film. The WDM is more robust than prior art WDM devices using flat TTFs.

Abstract: An optical add-drop multiplexer successively comprises a first ferrule, a first graded index (GRIN) lens with a bandpass filter attached thereon, an optical crystal, a second GRIN lens, and a second ferrule. An input and an output optical fiber are stationed in the first ferrule, and a dropping and an adding optical fiber are stationed in the second ferrule. An optical multiplexed signal from the input optical fiber is transmitted through the first GRIN lens to the bandpass filter. From the bandpass filter, an optical signal having a wavelength identical to a central wavelength of the bandpass filter is output to the dropping optical fiber, and other optical signals having other wavelengths are coupled with an optical signal from the adding optical fiber having a wavelength identical to the central wavelength of the bandpass filter and are transmitted to the output optical fiber.

Abstract: A wavelength selective switch is realized by combining a quantized dispersion element and an array of switching means. The quantized dispersion element enables to concentrate all the wavelengths within predetermined wavelength bands onto the same location in the switching array. With this arrangement, a low fill factor switching array can be used while maintaining good flat-top spectral performance with no spectral dips and improving alignment tolerances.

Abstract: An optical cross-connect switch is provided for routing optical data signals in an optical transport network.

Abstract: The invention proposes a Grouped Optical Add Drop Multiplexer (GOADM) comprising a periodic filter for forming a group of spaced optical wavelengths to be dropped or added.

Abstract: A self-adjusting optical add-drop multiplexer monitors the power in a drop signal and attenuates the power in an add signal to match the power in express WDM channels (signals). When used in a fiber network, and more particularly, in a metro network, the deleterious effects of optical amplification are reduced. Power attenuation is also used in an optical switching assembly particularly useful in two-fiber ring network. The optical switching assembly monitors drop channels from the two rings of the network and attenuates the add channel(s) accordingly. An optical switch operates to direct the drop signal from one of the two rings to a receiver in accordance with a control signal based on the monitored drop channels. The self-adjusting optical add-drop multiplexer also monitors the power in the drop signals and issues an alarm if the drop signal is of a power level above or below predetermined levels.

Abstract: The present invention provides for a method for optimizing the sequence of passive filter configuration in optical mux/demux devices for Wavelength Division Multiplex transmission systems and optical passive filter system obtained with that method, in which the optimization is obtained by taking care of the attenuation profile of the transmission optical fiber, and the variations of the spectral loss profile. The optimizing method permits to select the filter sequence maximizing the minimum span length of the network.

Abstract: Improved high-speed adaptive equalization is presented that may involve converting an optical signal into an electrical signal and performing equalization by (i) filtering the electrical signal with an analog filter according to at least one filter coefficient to produce a filtered output, (ii) generating an error signal from the filtered output according to an error function, (iii) providing at least one control signal to the analog filter for adjusting the at least one filter coefficient, (iv) detecting a relationship between a change in the at least one filter coefficient and a change in the error signal, and (v) adjusting the at least one filter coefficient according to the relationship to minimize the error signal. The least one coefficient may comprise a plurality of coefficients, and the relationship may be a gradient estimate having multiple components, each determined by varying only one of the coefficients and detecting a resulting change in the error signal.

Abstract: A wavelength division multiplex optical system includes a WDM combiner to provide a source signal, at least one transmitter coupled to an input of the WDM combiner, a broadband noise source, and a filter coupled between the broadband noise source and another input of the WDM combiner. In one embodiment, the filter is an optical notch filter. In an alternative embodiment, the filter includes a WDM demultiplexer coupled through plural filters to provide a plurality of noise signals and a WDM multiplexer coupled through at least one filter of the plural filters to respective noise signals.

Abstract: Wavelength drift in an optical WDM system between wavelengths launched by lasers (110) and received at a demultiplexer (50) can lead to disturbance of traffic signals if not identified and rectified rapidly. It is proposed to identify wavelength drift by determining a difference in temperature of the demultiplexer (50) for each channel between an actual temperature and a temperature for optimal transmission of the channel. The mean of these temperature differences for all channels is indicative of wavelength drift, while each difference is utilised to determine whether an individual channel is drifting in wavelength and to correct the drift. Wavelength drift can be detected and corrected whether sourced at a laser (110) or due to a temperature variation at the demultiplexer (50). Measurement and control can be performed during normal operation without impeding or degrading traffic flow. Wavelength influencing parameters other than temperature can be utilized.

Abstract: The present invention relates a fiber optical module. A first filter 5 transmits a light with a first predetermined wavelength (?A ), and reflects lights with a second predetermined wavelength (?B) and a third predetermined wavelength (?C). A second filter 6 transmits the light with wavelength ?B and reflects the light with wavelength ?C. A first light-receiving device 2 receives the light with wavelength ?A, and a second light-receiving device 3 receives the light with wavelength ?B, A light-emitting device 4 emits the light with wavelength ?C. A first optical fiber 1a leads the lights with wavelengths ?A and ?B to the first filter 5. A second optical fiber 1b leads the light with wavelength ?B reflected by the first filter 1a. A third optical fiber 1c leads the light with wavelength ?C emitted by the light-emitting device 4 to the second filter 6.

Abstract: A communications network having two complementary optical networks each connectable to a headend, each optical network comprising a plurality of periodic interleaving filters serially connected by optical waveguides such that an output port of one periodic interleaving filter is couple to an input port of another periodic interleaving filter, and wherein an input or output node of the network is formed by a non-serially connected input or output port of a periodic interleaving filter.

Abstract: A multi-channel passive DWDM multiplexing module, which can be installed in a standard shelf of a patch panel, takes multiple optical signals of defined frequencies and provides a multiplexed optical output. The module simplifies greatly intraoffice fiber optical connections by situating itself adjacent where the fiber optical cables are terminated, thus eliminating fiber optical cable routing through overhead racks. The module saves inter-office fiber optical resources by providing passive DWDM multiplexing, which combines multiple optical signals into one fiber optical cable. The module further saves cost on spare parts at each central office by providing a maintenance connection that can be alternately used as a spare input connection.

Abstract: An optical filter comprises a multimode waveguide, and first and second coupling waveguides which communicate with the multimode waveguide at respective ends thereof. Filtering is achieved by the effect of self-imaging in the multimode waveguide. The filter further comprises one or more series of aperture within the multimode waveguide, the or each series being located at a longitudinal position within the multimode waveguide at which 1-to-N way intensity division of an input optical field occurs, the optical field being the lowest order transverse mode of the coupling waveguides. The (one or more) series of apertures reduces the transmission of the filter at wavelength other than those corresponding to transmission peaks of filter's transmission function, thus providing improved filtering performance compared to prior art optical filters based on self-imaging.

Abstract: The optical receiver includes: an optical input port for receiving WDM signals; a transmittable-wavelength-variable filtering unit which transmits, of the received WDM signals, a light signal in a predetermined transmittable wavelength bandwidth with a desired central wavelength of ?i (i=1 to n: n is an integer number greater than 2); an optical output port which outputs the remaining light signals at wavelengths (?i) (k=1 to n; k?i) untransmittable through the transmittable-wavelength-variable filtering unit; and a control unit which controls the central wavelength so that the level of the light signal passing through the transmittable-wavelength-variable filtering unit is the maximum. It is whereby possible to flexibly accommodate changes in number of channels combined in a WDM system, and to adaptively minimize ASE light leaking into the photoreceptor of the optical receiver even in a CWDM system with wide channel spacing.

Abstract: An add-drop multiplexer is described, in one embodiment the add-drop multiplexer includes an optical transmission signal input port adapted to receive a wavelength division multiplexed optical transmission signal, an optical transmission signal output port adapted to output at least a portion of the wavelength division multiplexed optical transmission signal, an add-drop optical channel port adapted to receive an optical add channel and output an optical drop channel, and a wavelength selective optical filter arranged between the optical transmission signal input port, the optical transmission signal output port and the optical add-drop channel port. The wavelength selective optical filter reflects optical channels that will continue through the add-drop multiplexer along a transmission line to the optical transmission signal output port and permits an optical channel that is to be dropped to pass therethrough.

Abstract: A reconfigurable optical blocking filter deletes a desired optical channel(s) from an optical WDM input signal, and includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that tilt between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimators, diffraction grating, and Fourier lens, collectively collimate, separate and focus the optical input channels onto the array of micro-mirrors. The optical channel is focused on the micro-mirrors onto a plurality of micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels. To delete an input channel of the optical input signal, micro-mirrors associated with each desired input channel are tilted to reflect the desired input channel away from the return path.

Abstract: Improved designs of optical devices for processing optical signals with own or more specified wavelengths are disclosed. According to embodiment, a filter mirror assembly appears an “L” shape and provides a filtering function as well as a reflecting function. The filter mirror assembly is so mounted that a rotation thereof will not alter the optical path the beam positions of signals resulted from the filter mirror assembly.

Abstract: A connector to an optical fiber comprises a prism, a ferrule and an aspheric lens. The prism includes a triangular wedge element having a first surface, a second surface and a base. The ferrule guides the optical fiber so as to contact the optical fiber with the first surface of the prism. The aspheric lens is integrated on the second surface, the integrated aspheric lens being positioned so that the prism serves to redirect a light beam at an angle relative to an axis of the optical source input through total internal reflection by utilizing the base of the triangle wedge element. The aspheric lens serves to collimate the redirected light beam or focus the light beam before being redirected. This arrangement may, for example, be used within a WDM system to multiplex and de-multiplex several wavelengths of light, using a “zig-zag” optical path configuration and thin film filters to separate the wavelengths.

Abstract: The invention relates to wavelength division multiplexing (WDM) and demultiplexing of optical signals using optical filters in free space. To minimize dispersion, the present invention uses relatively small angles of incidence. To avoid the need for a large package, the present invention utilizes reflective prisms to steer the reflected beams to provide a lateral shift in the beam path that ensures that the necessary space is provided between the input/output ports. Devices including a single adjustable filter are disclosed, along with devices having a plurality of filters.

Abstract: A plug-in, optical add/drop (OAD) device includes a filter for adding and dropping a light beam of wavelength (?k) from a combined light beam having individual beams of different wavelengths (?1 . . . n). Several devices can be selectively integrated to create an optical communications system that will handle “n” different optical communications circuits. In operation, the devices are individually connected (plugged-in) to a GBIC, and they are serially connected (plugged-in) to each other. Consequently, immediately upstream from a device, the combined light beam includes wavelengths (?1 through ?n). On the other hand, the combined light beam immediately downstream includes (?1 through ?k?1 and ?k+1 through ?n).

Abstract: An optical add/drop multiplexer may be formed using ring resonators. In some embodiments, ring resonators may be used instead of Bragg gratings in a Mach-Zehnder interferometer configuration. One or more wavelengths may be added or dropped or a band pass of wavelengths may be added or dropped in a wavelength division multiplexed system.

Abstract: Devices, such as node and network elements for use in communications systems, which include a plurality of ports, each having an input and an output, a plurality of splitters corresponding to the port inputs, a plurality of combiners corresponding to the port outputs, a plurality of signal paths between the splitters and the combiners, wherein each of the signal paths includes a signal varying device, and a plurality of protection devices connected between the splitters and the combiners, wherein each of the plurality of protection devices includes a signal varying device and provides a protection path corresponding to a plurality of the signal paths, and wherein at least one splitter has at least one unused output after the signal paths and the protection paths are connected, and wherein at least one combiner has at least one unused input after the signal paths and the protection paths are connected.

Abstract: Systems are described that disperse the wavelength bands corresponding to the channel centers at a faster rate than the bandwidth of the channels themselves. An embodiment consists of a double element system including a grating, to create the initial separation, and a segmented mirror with multiple flat facets of different tilt, which reflect each spatially separated channel at a different angle. The size, position and angle of the facets are designed to match the spacing and position of individual channels of known wavelength and number that are diffracting from a grating with a predefined period, a set distance from this device. This system enables the individual channels to be re-imaged at some later point with a large separation between the channels, relative to their spatial size.

Abstract: An optical multiplexing apparatus of a low cost is capable of reliably multiplexing a plurality of optical signals having a narrow wavelength interval, while suppressing the nonlinear optical effect and the crosstalk, and a multiplexing method. The optical multiplexing apparatus includes a first optical multiplexer for multiplexing, among a plurality of optical signals that are input with directions of linear polarization of the neighboring wavelengths being differed to each other, optical signals having odd wavelength numbers while maintaining their polarization states. A second optical multiplexer multiplexes optical signals having even wavelength numbers while maintaining their polarization states, and a third optical multiplexer multiplexes, at an output unit thereof through first and second input units having sharp filtering characteristics, the optical signals multiplexed by the first and second optical multiplexing means, to output WDM signal light.

Abstract: A multiple-channel passive DWDM multiplexing module, which can be installed in a standard shelf of a patch panel, takes multiple optical signals of defined frequencies and provides a multiplexed optical output. The module simplifies greatly intraoffice fiber optical connections by situating itself adjacent where the fiber optical cables are terminated, thus eliminating fiber optical cable routing through overhead racks. The module saves inter-office fiber optical resources by providing passive DWDM multiplexing, which combines multiple optical signals into one fiber optical cable. The module further saves cost on spare parts at each central office by providing a maintenance connections that can be alternately used as a spare input connection.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: A method and apparatus for generating a series of positive and negative signals from an optical signal. The optical signal is fed into a loop of optical fiber. The loop of optical fiber is provided with a first and second directional coupler. As the optical signal circulates through the optical loop, the first and second directional coupler extract a percentage of light from the optical signal, and couple the extracted light to a photodetector which converts the extracted light into electrical energy. The present invention also provides an impulse cancellation line. The impulse cancellation line is provided to neutralize the problematic initial light extracted from the optical signal in the first directional coupler and coupled to the photodetector. However, as the optical signal continues to circulate through the optical loop, the extracted light is not neutralized.

Abstract: An electromagnetic matched filter based multiple access communications system having a source of modulated pulses from a digital data stream; an initial filter which shapes the incoming modulated pulse into a desired pulse for transmission across the communication medium; a second filter, identical to the initial filter, which is matched to the pulse which exit the communication medium, a detector which converts the modulated pulse stream into the original digital data stream, and signals which are designed with specific mathematical properties which make the system efficient and minimizes crosstalk between channels. The signals decay rapidly from the central lobe at a higher than 1/x rate and the zero points of the autocorrelation function having high order multiplicities. The type of system allows multiplexing of multiple data streams with much greater flexibility, robustness, and density.

Abstract: An optical component array allowing expansion of the occupied bandwidth on an existing optical transmission network without disrupting signal traffic. Wavelength selective filters (16, 30; 20, 34) and optical components, such as amplifiers (18, 32) are arrayed for use with a wavelength division multiplexed optical transmission system to transmit a selected portion of a transmission spectrum to an amplifier path and reflect the remainder of the spectrum. Wavelength selective filters and associated amplifiers are arranged in a cascade configuration with a bypass path (35, 37). Additional wavelength selective filters and amplifiers can be added in the bypass path without disrupting existing signal traffic, and such additions can provide for a remaining bypass path, thus allowing further expansion. This configuration provides an expandable amplifier array with a low initial cost.

Abstract: Disclosed is an apparatus for controlling wavelength-division-multiplexed light wherein overall power of wavelength-division-multiplexed light is rendered constant through control for uniformalizing the level of only one wave of maximum power, and wherein the levels of respective channels are made substantially uniform. Optical level control means controls the optical level of propagating wavelength-division-multiplexed light, and a portion of the wavelength-division-multiplexed light output from the output level control means is branched to a tunable optical filter, which selectively outputs the light of each wavelength contained in the wavelength-division-multiplexed light. The light of each wavelength output from the optical filter is photoelectrically converted to an electric signal by photoelectric conversion means.

Abstract: A multiplexer/demultiplexer optical system component that is passively aligned upon assembly is disclosed. The optical system includes a lens block and a mirror-filter block. In some embodiments, optical filters are positioned and epoxyed to the mirror-filter block using a positioning tool. In some embodiments, optical filters are positioned and epoxyed on a support structure which has been etched to receive the optical filters. The mirror-filter block is a block having flat surfaces, one of which is a flat reflecting surface. The lens block is formed by injection molding and includes a barrel for holding and positioning an optical fiber, placement for a collimating lens, and placements for focusing lenses such that, when assembled, light incident on each of the focusing lenses propagates along the optical axis of the focusing lens. In some embodiments, the collimating lens and the focusing lenses are integrally formed with the lens block.

Abstract: Methods and apparatus for multiplexing and demultiplexing optical signals. An interleaver having a modified Mach-Zehnder interferometer as a first stage is used as a wavelength division multiplexer. This first stage is combined with one or more cascaded stages, each having a beam splitter and an optical delay element. A light beam including a number of signals at different wavelengths is received. The beam is split such that approximately half of each signal is contained in one of two sub-beams. One of the two sub-beams passes through a delay element, which provides a phase shift. The two sub-beams are recombined and split again. Each wavelength adds constructively or destructively in the new sub-beams such that the signals are separated—some wavelengths are in one of the new sub-beams, some are in the other. One of these sub-beams is delayed, and the two are combined and split again, improving the separation.

Abstract: A method of fabricating a WDM unit consists of attaching a first and a second GRIN lenses to opposite faces of a WDM filter. A dual fiber pigtail and a single fiber pigtail are mounted in corresponding glass tubes. The glass tube with the dual fiber pigtail and the glass tube with the single fiber pigtail are mounted on the second GRIN lens and the first GRIN lens respectively. The position of the dual fiber pigtail and the single fiber pigtail are adjusted with respect to the second GRIN lens and the first GRIN lens respectively to obtain the best optical property. The invention prevents the WDM filter from tilting during temperature variation by sandwiching the WDM filter in between the two GRIN lenses, and further prevents the WDM unit from increasing the reflection loss and insertion loss.

Abstract: A dynamic gain flattening filter includes a first filter stage. The first filter stage has a first tunable coupling member and a first differential delay with first and second tunable delay paths. The first tunable coupling member adjusts an amount of power of the optical signal that is divided onto the first and second tunable delay paths of the first differential delay.

Abstract: An apparatus for wavelength multiplexing optical signals, wherein the apparatus includes at least one optically conductive sleeve, at least one collimating lens positioned to receive a optical signal from the at least one sleeve, and at least one dichroic splitter positioned to receive the optical signal from the at least one collimating lens. A filter may further be positioned to receive the optical signal from the at least one dichroic splitter in order to further filter the optical signal. The apparatus for wavelength multiplexing is configured to provide optical isolation of at least 75 dB via the combination of the at least one dichroic splitter and filter elements.

Abstract: A device for processing optical signals comprises sources each delivering, substantially simultaneously, optical signals in accordance with a comb of at least two different wavelengths or a continuum of wavelengths. It further comprises multiplexers adapted to deliver to at least one primary port a multiplex of channels corresponding to chosen bandwidths produced from optical signals received at secondary ports each provided with selective spectral filters adapted to pass optical signals whose wavelengths belong to one of the bandwidths corresponding to one of the channels of the multiplex. It further comprises optical routers for routing the optical signals delivered by the sources to secondary ports of the first multiplexers as a function of instructions received.

Abstract: A carrier is extracted from a stream of optical signals including plural wavelength division, multiplexed carriers modulated by corresponding signals while a carrier having the same wavelength as the extracted carrier is inserted into the stream. The stream of optical signals and the carrier to be inserted are coupled to a tunable wavelength selector having first wavelength and phase shift properties. Tuning of the wavelength selector is changed, so it has second wavelength and phase shift properties such that the entire stream of optical signals is coupled from an input port to an output port via the tunable wavelength selector, and the extracting and inserting operation is not performed while the tuning is changed. The other carriers are coupled from the input port to the output port via the selector while extracting and inserting are performed, and the selector has the first wavelength and phase shift.

Abstract: In a WDM optical network, optical components of optical add/drop multiplexers (OADMs) at different nodes are made independent of the optical channel wavelengths to be dropped and added. Groups of optical channels each comprise a respective channel in each of a plurality of optical bands of channels having adjacent wavelengths, and the OADMs use tunable optical filters to drop and add channels in a selected group. A remote source supplies unmodulated optical carriers at channel wavelengths via an optical carrier fiber to each node, and at least one, conveniently all, of the optical carriers in a respective optical band is/are modulated with a signal to be transmitted via the add filter.

Abstract: In tunable systems, during a tuning cycle, express channels or wavelengths are dropped as the system sweeps through its free spectral range (FSR) before stopping at the desired wavelength to be dropped. This is disadvantageous as the data information in the express wavelengths suffers a hit or momentary increase in bit error rate (BER). Techniques for eliminating or at least minimizing interference to those channels or wavelengths are disclosed. According to one aspect of the present invention, the wavelength selection to be dropped is done “off-line” and does not affect the express channels. An optical reference source is used to set up and tune a drop filter. Once the filter is set to the appropriate dropping wavelength, a secondary filter is scanned to cause the channels to be shunted to the drop filter. If the wavelength of a signal and the drop filter matches, the signal is dropped.

Abstract: The present invention relates to an optical device (10) and a corresponding method for (de-)multiplexing optical signals. The devices (10) comprises a multiple channel port (28), at least a first and a second separated channel port (30, 32), and a diffraction unit defining wavelength specific beam paths (46, 48) between the multiple channel port (28) and the separated channel ports (30, 32). The diffraction unit includes a diffraction grating (12) and a plurality of mirrors (16, 18) adapted for receiving and reflecting the optical beams (46, 48) from and to the diffraction grating (12.) The mirrors (16, 18) are individually angled for reflecting the optical beams (46, 48) at different angles (24) to the diffraction grating (12).