Abstract: Fibre optic apparatus for accurate and repeatable measurements of light comprising one or more wavelength ranges, and system employing the apparatus. The apparatus according to the invention comprises: a directional coupler adapted to lead the light into an optical fibre, said optical fibre containing at least one analysis filter for each wavelength range, said analysis filters consisting of at least one fibre-optical Bragg-grating (FBG) which reflects incident light with a chosen wavelength back through said directional coupler and onto a detector having an associated signal processing unit, a modulator device for pulsing the incident light with a chosen pulse width, and an optical fibre delay line in front of each analysis filter, with a length adapted to provide for a sufficient time delay larger than the pulse width, so that the pulses reflected from each analysis filter at different wavelengths can be separated in time and thereby be demodulated in the signal processing unit.

Abstract: A method introduces variable time offsets into a stream of optical pulses. The method includes receiving a plurality of coherent optical pulses, receiving a plurality of control signals, and forming a coherent pulse array (CPA) from each pulse in response to one of the received control signals. Temporal spacings between pulses of each CPA are responsive to the associated one of the received control signals. For optical control signals, response times can be very short. The method further includes transmitting each pulse through a dispersive optical medium. The act of transmitting makes pulses of each CPA overlap to form an interference pattern.

Abstract: An optical cross-connect with integrated optical signal tap is disclosed. In one embodiment, the switch includes two or more optical fiber input ports, lenses to produce collimated beams, one or more optical taps to couple a portion of the optical power from one or more input ports to one or more sample ports, movable mirrors to connect any input port with any output port, two or more optical fiber output ports, and lens to couple collimated beams into the output ports.

Abstract: An optical filter has a first long-period grating and a second long-period grating formed in a unitary optical fiber. A difference is not less than 100 nm between a wavelength at which optical coupling is maximum between core-mode light and cladding-mode light of a predetermined mode number in the first long-period grating and a wavelength at which optical coupling is maximum between core-mode light and cladding-mode light of the same mode number as the cladding-mode light of the predetermined mode number, in the second long-period grating. This optical filter can be constructed in compact size and can readily implement a desired transmission characteristic.

Abstract: An optical wavelength filter having an optical coupler, for suppressing the generation of a double peak caused by a difference of propagation constants between intrinsic modes of light in an optical coupler. The optical wavelength filter includes first and second optical couplers for exciting multiple modes of light in each wavelength of WDM light and providing a phase difference of p/2 between different modes of multiple modes of light, and a mode converter provided between the first and second optical couplers. The mode converter performs mode conversion between the modes of light belonging to a specific wavelength, whereby the phase difference of each mode of light constituting the light of a specific wavelength, and the phase difference between the modes of light constituting the light of another wavelength, are independently adjusted so as to output light of a specific wavelength and light of another wavelength from separate output ports.

Abstract: A method of manufacturing a compact fiber coupler. On a semiconductor substrate, a V-groove with a radius curvature R is formed. Then, a glue is positioned at both sides of the V-groove, and the glue is absorbed from both sides of the V-groove by capillarity. A first optical fiber and a second optical fiber are respectively fixed in the V-groove so that the cladding of the first optical fiber and the second optical fiber can be polished to form a first side-polished region and a second side-polished region. Thus, the compact fiber coupler is accomplished by aligning and fusing the first side-polished region and the second side-polished region together, in which a coupling region is formed between the first side-polished region and the second side-polished region.

Abstract: In an optical amplifying technique using remote pumping, an optical transmitting apparatus and an optical repeating apparatus are provided. An optical repeating apparatus comprises a first optical transmitting unit, a first loopback unit, a second optical transmitting unit, a second loopback unit, and four optical couplers, wherein transmission light and reception light are transmitted through one optical fiber cable, whereby the installation cost and maintenance cost of the optical cable are decreased. Disconnect of the optical cable is detected by a monitoring function using pumping light and residual pumping light, whereby reliability and safety of the system are remarkably improved. Additionally, adjustment of the optical output level of the repeating station can be most suitably set according to an actual transmission distance.

Abstract: A micromechanical optical switch structure, that may be integrated to form an array of optical switches, switches light between a main waveguide and a switched waveguide. The switched waveguide has a coupling portion and two flexible portions and is coupled to a movable cantilever arm. The cantilever arm is configured to move at least the coupling portion of the switched waveguide between first and second positions with respect to the main waveguide. In the first position, the switched waveguide is evanescently coupled to the main waveguide and in the second position, the switched waveguide is not evanescently coupled to the main waveguide. The movable cantilever arm may be formed with bimaterial arms that move the switched waveguide in response to heat or a piezoelectric potential being applied to the arm or they may be formed with an electrostatic plate that moves the arms in response to an electrostatic potential.

Abstract: An optical device including a microstructured fiber pumped by an external pulsed-light source. In one embodiment, the microstructured fiber includes two waist regions functioning as a tunable attenuator and a wavelength shifter, respectively. Output wavelength of the optical device is selected by attenuating the pump light in the first waist region and then passing the light through the second waist region to shift the pump energy to a new spectral band. An optical device of the invention configured with two or more microstructured fibers generates two or more synchronized pulsed beams, each at a different characteristic wavelength. Certain embodiments of the invention provide an inexpensive, compact, energy-efficient multi-wavelength synchronized pulsed-light source.

Abstract: The invention relates to polymer compositions which enable thermooptic control of signal attenuation in the ultraviolet, visible and near infrared (NIR) regions of the electromagnetic spectrum, and devices incorporating such compositions. The compositions are derived from polymer mixtures which exhibit a cloud point phase transition at a temperature in the range of a thermooptically controlled device such as a programmable waveguide attenuator, a programmable neutral density filter, or an optically absorbent switch. An especially preferred embodiment of the invention comprises a mixture of a high molecular weight chlorotrifluoroethylene fluid and a wax with an “ON-state” insertion loss of below 0.1 dB/cm and an extinction ratio of 22 dB/cm in the 1550 nm NIR telecommunication band.

Abstract: An integrated-optical device including a substrate having waveguide and a plurality of electrodes to receive electrical signals for controlling the light transmission through the pathways. The waveguide pathways are in an interaction zone of an electro-optically active waveguide material whose refractive index changes in response to electrical signals applied to the electrodes, and also in an access zone providing optical access to the interaction zone. The active waveguide material in the interaction zone is preferably a different material from the waveguide material in the access zone, enabling improved performance and/or simpler fabrication in a number of described respects.

Abstract: A polarization-combining fused-fiber optical coupler is made of polarization maintaining (PM) fibers spliced to non-birefringent single mode (SM) fibers which are fused and drawn near the splicing to form a coupler with an adiabatic tapered profile. The linearly polarized light injected into PM fibers travels through the coupler where the power of the two polarizations is combined and transmitted to one output fiber. The method for producing such coupler involves splicing a pair of PM fibers to a pair of SM fibers, then injecting linearly polarized light into each PM fiber and fusing and drawing SM fibers to form an adiabatic coupler with maximum power transmission at a desired wavelength going to only one output fiber.

Abstract: An optical apparatus includes an optical fiber. A plurality of individual optical fiber deformation structures are positioned adjacent along a length of the optical fiber. Each of an individual optical fiber deformation structure introduces a mechanical or index deformation of a portion of the optical fiber to create perturbation in the optical modes in the fiber and provide a coherent coupling between two modes in the optical fiber.

Abstract: An optical termination element for terminating an optical fiber carrying a signal of first maximum power level comprises a termination fiber which is unable to propagate a fiber fuse when the signal power is below a threshold power level which is greater than the first maximum power level. The termination fiber is designed by selecting values of the core diameter and the higher mode cutoff wavelength. The intention provides a termination component in which a fiber fuse can not be initiated at the maximum power to be provided to the termination.

Abstract: A nanophotonic directional coupler is disclosed for transferring light from one waveguide to a second waveguide. The directional coupler is formed within relatively small dimensional parameters and can be formed to accommodate light signals of both transverse electric (TE) and transverse magnetic (TM) polarizations.

Abstract: The figure-8 optical fiber pulse laser according to the present invention produces stable femto-second optical pulses using DI-NOLM. The optical amplifier is not included in DI-NOLM, instead, it is located at the unidirectional linear loop part. And the noise due to the bidirectional gain difference of the optical amplifier is reduced. Two optical fibers of different dispersion values are used at DI-NOLM. Therefore, the present invention provides a figure-8 optical fiber pulse laser using DI-NOLM improving the switching characteristic. Especially, the stable femto-second laser according to the present invention is applicable for the many applications such as high-speed reaction measurements, laser treatments, and medical lasers.

Abstract: An optical module (1) which contains at least one optical component (2) whose one optical input/output is directed towards an optical fiber (4) to which it is to be coupled. At least one additional optical waveguide (6) is arranged between this optical component (2) and the optical fiber (4). The optical component (2) is provided with an optical waveguide (3) whose end (5), facing towards the optical fiber (4), is tapered or widened for a modal field adaptation. Additionally the end of each interposed optical waveguide (6) facing towards the optical fiber (4) is also tapered or widened for a modal field adaptation.

Abstract: An optic apparatus includes an optical fiber with a cladding surrounding a core and a core-mode blocker included in at least a portion of an interactive region of the optical fiber. A mode coupler is coupled to the optical fiber and couples a first mode to a different spatial mode in a forward direction of the optical fiber.

Abstract: In the optical multiplexer/demultiplexer according to the invention, an MMI (multi mode interference) coupler having a percentage coupling of about 50% is used as first and second optical couplers, and a directional coupler having a percentage coupling of less than 10% is used as third and fourth optical couplers. By virtue of this constitution, the optical multiplexer/demultiplexer according to the invention has a small dependency upon wavelength and can be used in a wide waveband, is less susceptible to a preparation error, and, at the same time, has good wavelength flatness in passband and a wide rejection band.

Abstract: The present invention provides a photonic crystal waveguide comprising: a substrate; a bottom cladding layer over the substrate; and a core layer over the bottom cladding layer, the core layer having a uniform distribution of holes, wherein the core layer has at least a waveguide region which is thicker than a remaining region of the core layer to cause a refractive index guide effect, or wherein the core layer has at least a waveguide region, on which a dielectric pattern is provided which has a refractive index higher than a substance in contact with a top surface of the core layer, or wherein the core layer has at least a waveguide region, and the holes except on the waveguide region are filled with an air, whilst the holes on the waveguide regions are filled with a filler material having a refractive index higher than 1.

Abstract: To provide a block gain equalizer, which controls an amount of gain slope, and does not cause any loss in an optical signal. A block gain equalizer 201 branches an optical signal transmitted from an optical fiber transmission path 101N by an optical coupler 112 to take out a supervisory signal 119 by a band pass filter. An electric signal 122 after this photoelectric conversion is inputted into a gain control circuit 207 to read slope correction data for flattening the gain. The gain control circuit 207 supplies a gain control signal 208 to a semiconductor laser 204 to drive it by power which corresponds to the gain slope for flattening the gain, for pumping an erbium doped fibers 202 in accordance with a backward pumping system. Thereby, the block gain equalizer 201 is capable of flattening the frequency characteristic without any loss in optical signal. It is also possible to adjust the gain by an attenuator as required. Also, for the pumping system, various systems can be adopted.

Abstract: An optical device for the differentiation of a first optical signal and an optical signal lagging behind the first, in which the differentiation is represented by a signal carried by a continuous wave passing through the two arms of an interferometer including media with an index that depends on the optical power passing through them. The delayed signal is the first signal fed back to one of the arms through a delay.

Abstract: The present invention relates to an optical waveguide coupler device. As shown in FIG. 1, the optical waveguide coupler device 8 comprises two optical waveguide cores 2, 3 formed on the surface of a substrate 1. The optical waveguide cores 2, 3 are covered by lower and upper cladding layers 6, 7 both formed on the substrate 1; and the two optical waveguide cores 2, 3 are brought close to and in parallel with each other at two sites to form two directional couplers 4, 5 there. The cross-section and refractive index of each of the optical waveguide cores 2, 3 and the parameters of other elements of the circuit are optimized such that an optical signal is reliably routed by the circuit without undergoing a wavelength shift even when the circuit is exposed to the changes of ambient temperature.

Abstract: A system and method for twisting together two fibers to create an optical fiber coupler is disclosed. In one embodiment, the two optic fibers are threaded through a chuck, which is rotated by a motor to create an amount of twist in the two optical fibers necessary to cause a light signal transmitted through the twisted fibers to have a desired polarization state. A heater applies heat to the twisted fibers while rotating the chuck to create an optical fiber coupler.

Abstract: The present invention provides an optically-amplified bidirectional optical adddrop multiplexer for a bidirectional WDM optical communication system including two counterpropagating WDM optical signals. Each counterpropagating WDM signal enters the bidirectional add-drop multiplexer and is placed on an optical path, which does not include the other WDM optical signal. Each WDM optical signal may be amplified and have one or more optical channels added to or dropped from the respective signal. In an exemplary embodiment, one of the bidirectional WDM signals includes optical channels located in the C-band of an EDFA while the other bidirectional WDM signal includes optical channels located in the L-band of and EDFA. In this manner, an optical amplifier particularly selected for channels in a particular gain region may separately amplify each the separated bidirectional WDM signals. Each counterpropagating WDM signal exits the bidirectional add-drop multiplexed and rejoins the bidirectional optical waveguide.

Abstract: An optical-to-optical wavelength converter for converting a plurality of optical bits from a first wavelength in a first wavelength band to a second wavelength in a second wavelength band. The optical-to-optical wavelength converter employs a directional coupler. The directional coupler includes at least one optical element having an index of refraction, which changes in response to optical power substantially in the first wavelength band.

Abstract: An optical interleaver. The interleaver is based upon the Mach Zender interferometer. At least one of the optical paths joining opposed couplers of the arrangement includes an optical image transfer element intermediate the ends of fibers associated with the couplers. In one embodiment, the optical image transfer element is a single imaging lens whereas, in another embodiment, the element consists of an aligned pair of collimating lenses. During fabrication, optical positioning stages support the optical image transfer element and fiber ends to permit ready adjustment of &Dgr;&THgr;, the optical path length difference between the arms of the interleaver, to assure predetermined optical channel spacing of an input DWDM signal.

Abstract: An integrated-optical device including a substrate having waveguide and a plurality of electrodes to receive electrical signals for controlling the light transmission through the pathways. The waveguide pathways are in an interaction zone of an electro-optically active waveguide material whose refractive index changes in response to electrical signals applied to the electrodes, and also in an access zone providing optical access to the interaction zone. The active waveguide material in the interaction zone is preferably a different material from the waveguide material in the access zone, enabling improved performance and/or simpler fabrication in a number of described respects.

Abstract: The construction of directional couplers according to the invention with the aid of integrated optical waveguides makes it possible to produce such directional couplers in series very compactly and relatively easily. In this connection, the integrated optical waveguides in the coupling region have a smaller cross section than the cross section outside the coupling region. Consequently, it is possible to keep the spacing of the waveguide segments in the coupling region of a directional coupler according to the invention sufficiently far away from one another to minimize the error tolerance conditions in the manufacturing process. This is particularly advantageous if the difference in the refractive indices between the core of the integrated optical waveguide and its surroundings is very large.

Abstract: An orientation switchable optical fiber 1 has an elongate body 8 with two ends N, F. The body 8 is twisted intermediate the two ends at M and has a central core region 14 in which light carried by the fiber is confined. Passive means in the form of air channels 6 extend substantially from one end N to substantially the other end F of the body 8. The passive means 6 promotes orientation of light in at least one first transverse axis A of the body 8. Active means in the form of thermally stressable rods 10 extend substantially from the location of the twist M to substantially the other end F of the body 8. The active means 10 is switchable between an off state in which it is ineffective and an on state in which it is effective to promote orientation of light in at least one second transverse axis B of the body 8.

Abstract: An apparatus for measuring the chromatic dispersion profile of an optical fiber using two light sources 1 and 2 at least one of which is tunable in wavelength, in which two light beams of different wavelengths from said two light sources are injected into a optical fiber under test 7 and the four-wave mixing light that is generated by interaction between said light beams of different wavelengths is measured with an optical time domain reflectometer (OTDR) 9, characterized in that an optical bandpass filter 8 having a fixed central frequency is provided at a stage upstream of said optical time domain reflectometer (OTDR).

Abstract: A tap-off capable of easily extending a hybrid fiber coaxial network without complicated cable handling and signal disruptions. The tap-off comprises a primary distributor connected to a directional coupler. Additional distributors are divergently connected to the primary distributor and include terminal distributors. Bridges are divergently connected to the terminal distributors, and an intermediate distributor is connected between the directional coupler and the primary distributor. The tap-off also has at least one extension port and at least one intermediate cable connecting the extension port with the intermediate distributor. Each bridge is connected to a drop cable for providing a signal to a subscriber. The intermediate distributor distributes the signal to the primary distributor and to the extension port. The tap-off further comprises an additional extension tap-off, which includes an input port connected to the extension port, distributors, and bridges.

Abstract: To form an optical element (20), in particular an interferometric sensor, an optical fiber (1) is placed tangent to a cylindrical supporting element (2); a straight portion (1a) of the optical fiber and the supporting element are surface fused; and a cavity (26) is formed in the optical fiber (1), the cavity being defined by facing surfaces (27,28) of the straight portion (1a) substantially perpendicular to the axis of the straight portion (1a). The optical fiber (1) and supporting element (2) may be subjected to traction during surface fusion, to form a small cross-section portion close to the cavity, and which, when light is conducted by the optical element, provides for reducing the amount of light dispersed in the cavity.

Abstract: The invention has improved parameters when compared iwth prior art devices; pump power was decreased by four orders of magnitude and amplification of signal was increased by two orders of magnitude. The main features of the invention are the following. A nonlinear optical waveguide is made on the basis of a layered MQW-type structure, where unidirectional distributively coupled waves (Ip, Is), e.g. coupled waves having orthogonal polarizations, interact. The wavelength of optical radiation is chosen close to the wavelength of resonance in the structure. Input/output elements, taking into account the asymmetry of the cross section of the nonlinear optical waveguide, are mounted at the input and output of the nonlinear waveguide making up a compact nonlinear-optic module. A small electric current is injected across said nonlinear optical waveguide through electrodes, so as to increase the gain and decrease the pump optical power to a high degree.

Abstract: A dynamically reconfigurable optical switching system serves as a node on a fiber optic telecommunication network. The optical switching node utilizes an optical switching fabric, a switching device with multiple input ports and multiple output ports that can be controlled to direct a signal from a particular input port to a particular output port. The switching fabric is connected to optical components such as wavelength demultiplexers, wavelength multiplexers, and optical signal conditioners such as amplifiers, wavelength shifters, and signal correctors. The switching fabric is controlled via a switching node controller that includes an electrical connection to a network management infrastructure. The system architecture allows an incoming optical signal to be directed through any desired combination of optical components via multiple traversals of the switching fabric.

Abstract: A directional coupler of the present invention includes a substrate; a first waveguide layer; a second waveguide layer disposed over the first waveguide layer; a separation layer which separates the first waveguide layer and the second waveguide layer at least at one end; and an optical coupling section which is a predetermined region in which the first waveguide layer and the second waveguide layer approach or come in contact with each other. Each of the first waveguide layer and the second waveguide layer is integrally and continuously formed.

Abstract: This invention encompasses a method for the manufacture and rapid assembly of large screen fiber optic displays (1, 2) containing a very large number of individual fibers (thousands to hundreds of thousands, or more). The display surface is modularized into relatively small, thin, interchangeable, injection-molded square or rectangular tiles (3) to simplify manufacture and assembly. The hundreds of fibers (7) required for each tile (3) are machine-configured into a plurality of flat, flexible fiber optic ribbon cables (4), each cable (4) comprised of a planar geometric array of optical fibers (7) embedded in a thin adhesive matrix (8). The image emission end of each flat, flexible fiber optic cable (4) is a fiber manifold (20) joined to an injection-molded thermoplastic array of light guides (11), each fiber terminating in a single light guide or emitter (12).

Abstract: Optical systems of the present invention generally include at least one optical amplifier having a first pump source configured to supply power to said amplifier via a first pumping paths. A second pumping path is provided to supply power to the amplifier from a second pump source configured to replace power from the first pump source. The amplifier allows the replacement and repair of a pump source during operation by providing in-service hot swap capability, which increases the overall availability of the amplifier. The pump source can also be changed during operation to allow reconfiguration of the optical system.

Abstract: A broadband partial reflector is located downstream from an optical combiner device. The partial reflector reflects a portion of the combined light back through the combiner device and back into the respective optical pump sources. There are no fiber gratings or other filters between the sources and the combiner device. Consequently, the sources are locked and/or stabilized according to the acceptance bandpass characteristics of the input ports of the combiner device. Since no gratings or other filters need to be located between the sources and the combiner device, the problem of insertion power loss due to spectral mismatch at the input ports can be avoided. In other words, self-aligned wavelength feedback stabilization is accomplished by reflecting a portion of the combined light signal back through the input ports of the combiner device.

Abstract: An integrated optical switch that has a low throughput loss during the “on” pulse, and a high throughput loss during the “off” period. The optical switch includes a substrate with at least two waveguide structures suitably formed on the substrate. One of the waveguide structures is substantially straight and connects an input port to an output port. During an “on” pulse, light may be guided along the substantially straight waveguide from the input port to the output port such that there is little throughput loss. During an “off” period, a voltage is applied across control electrodes such that the waveguides are coupled so that light does not reach the output port.

Abstract: An optical waveguide used in a WDM optical transmission system are fabricated by the following steps in order to be highly integrated and reduced in size and to have a more preferable design. Namely, a first cladding and a first core are formed on a substrate; at least the first core is etched so as to remain a first waveguiding part for guiding light and non-waveguiding parts, disposed on the both sides of the waveguiding part along a guiding direction of the guiding of light, for guiding no light and in such a manner that two grooves, having varying widths in the guiding direction respectively, are formed between the waveguiding part and each of the non-waveguiding parts; a second cladding is deposited on the remaining first core and the fist cladding; and the second cladding is reflowed by a heat treatment so as to be flattened.

Abstract: A bi-directional optical coupler is provided. The bi-directional optical coupler includes a package having a first side and a second side. A forward coupler and a reverse coupler are included in the package. The forward coupler receives DC electric signals at the first side of the package and transmits DC electric signals at the second side of the package. The reverse coupler receives DC electric signals at the second side of the package and transmits DC electric signals at the first side of the package. The inclusion of two couplers within a single package means that the two couplers are subject to the same temperatures and have similar degradation. For this reason, the two couplers remain matched in terms of efficiency.

Abstract: A Y-branch waveguide includes a single merging side waveguide, two branching waveguides, and a junction area waveguide provided between the merging side waveguide and the branching waveguides and formed in a tapered shape being thicker at the branching than at the merging side. The junction area waveguide and the branching waveguides are connected by two straight waveguides parallel to each other. The straight waveguides extend in the same direction as the direction of propagation of light inside the junction area waveguide, when light is injected from the merging side waveguide.

Abstract: A miniature dense wavelength division multiplexer (DWDM) is disclosed. A plurality of multi-window wavelength multiplexers (MWDM) are cascaded and optically coupled to form a tree, and each of the MWMDMs forming the tree comprises a microbend coupler. The forming of the MWDM tree is characterized by the absence of the bending of optical fibers external to the microbend couplers. A finished DWDM assembly measures less than 50 mm in width.

Abstract: An optical fiber structure for demultiplexing/multiplexing includes a coupler which splits an incoming signal with multiple channels into two substantially identical signals that are respectively processed to separate the closely located successive channel groups for further demultiplexing or multiplexing. The spectrum characteristics to process the two identical signals are so chosen that the channel distortion and/or transmission loss are minimized. In particular, multiple stages of splitter filters are used to shorten the transmission path a channel signal has to pass through. As a result, signal distortion and/or transmission loss are minimized and the channel groups are interleaved by a single channel group.

Abstract: The method of the present invention comprises the steps of providing a nonlinear optical loop mirror comprising a first optical coupler including first and second optical paths directionally coupled to each other, a loop optical path including first and second fibers having different characteristics for connecting the first and second optical paths, and a second optical coupler including a third optical path directionally coupled to the loop optical path; and supplying probe light and input signal light from the first and third optical paths, respectively, and outputting output signal light from the second optical path.

Abstract: An optical signal transmission system equipped with a magneto-optical modulator is provided. The magneto-optical modulator works to modulate an optical beam emitted from a light source and consists of a polarizer, a magneto-optical element, an analyzer, a dc field generator, a high-frequency field generator, and an impedance adjuster. The dc field generator works to apply a dc bias field to the magneto-optical element. The high-frequency generator is responsive to the high-frequency signal from said high-frequency signal generator to apply a high-frequency field to the magneto-optical element. The impedance adjuster works to adjust impedance of the high-frequency field generator for establishing effective transmission of the high-frequency signal to the high-frequency field generator, thereby increasing a modulation range up to frequencies higher than an upper limit of typical magneto-optical modulators.

Abstract: A phasar (arrayed waveguide grating) including a segmented waveguide disposed between the phasar and one of the single-mode waveguides on either the input or output side of the phasar. The segmented waveguide is optimized to produce a flattened passband of the phasar, thereby minimizing variations in the phasar spectral response. The optimization may be performed by an evolutionary algorithm which generates random variations into the design population and selects the better members in a multi-generational selection process. The flattened passband phasar is particularly useful in a wavelength-division multiplexing (WDM) fiber communications network.

Abstract: An optical communication assembly includes a demultiplexer coupled to an input fiber, a multiplexer coupled to an output fiber and a plurality of optical fibers. Each optical fiber is coupled to one or both of the demultiplexer and multiplexer. A plurality of attenuators are each coupled to an optical fiber in the pluality of optical fibers.

Abstract: A fused fiber optic 1×4 or 2×4 coupler in which four optical fiber segments (A, B, C, D) extend longitudinally beside each other in a coupling region in which the fiber segments are at least partially fused together to form an assembly exhibiting a close packed cross section in which the fiber cores (11) are centered substantially at the corners of a four sided polygon having a pair or opposite internal acute angles substantially less than 90°.