Abstract: A mask having a center hole for passing through a center fiber, which is one of multiple fibers, and multiple surrounding holes for passing through surrounding fibers, which are the remainder of the multiple fibers, and a stress adjusting unit for holding stresses generated in the center fiber and surrounding fibers to a desired constant value, respectively, are installed. The surrounding fibers are rotated around the center fiber by rotating the mask. The center fiber and the surrounding fibers that have been twisted around the center fiber are heated with a heating apparatus and drawn. The center fiber and the surrounding fibers are fixed using a clamp installed between the stress adjusting unit and the heating apparatus.

Abstract: A light transfer device is provided that includes a first light pathway having a first input and a first output and a second light pathway having a second output. The second light pathway is coupled to the first light pathway, and light from the first input is transferable between the first and second light pathways. An active medium is positioned along one of the first and second light pathways, and the active medium is capable of receiving light that modifies the active medium so that the active medium controls the transfer of light between the first and second pathways.

Abstract: The present invention relates to an optical component of the waveguide array spectrograph type, the component comprising an inlet coupler and an outlet coupler between which said array extends, and including optical channels constituting inlets and outlets for the inlet and outlet couplers, the component being suitable for multiplexing and/or demultiplexing two optical signals of different wavelengths conveyed by two channels of the same coupler, wherein the waveguides of the array have lengths that are distributed in such a manner that two spectrum ranges of different center wavelengths both occur in said same coupler, said different wavelengths that are conveyed by the two channels each belonging to a different one of the free spectrum ranges.

Abstract: A passband-flattened phasar including two free space regions coupled by a plurality of waveguides having predetermined differences between their lengths so as to act as an arrayed waveguide grating. The phasar is particularly useful in a wavelength-division multiplexed (WDM) optical communication system transmitting multiple wavelength systems arranged in a wavelength comb with a constant wavelength channel spacing. The input waveguide is coupled to the first free space region through a Mach-Zehnder interferometer (MZI) having two waveguide arms of differing lengths receiving approximately equal amounts of the input signal. The arms differ in lengths so as to produce a phase difference between them. In a WDM network, the waveguide arm produce a phase difference such that the free spectral range of the MZI equals the wavelength channel spacing, such that the wavelength response of the MZI is the same for each of the WDM wavelengths.

Abstract: Tunable add/drop optical device for injecting or extracting (add/drop) at least a selected optical channel or carrier wavelength in or from a set of multiplexed channels or carriers of different wavelengths comprising a plurality of directional couplers (AD1 . . . AD6) and a plurality of phase-shift stages (SF1 . . . SF5) alternately connected in cascade, wherein each phase-shift stage defines a certain optical path length difference (&Dgr;L1 . . . &Dgr;L5) between two distinct optical paths of the stage. The tuning is performed modifying the refraction index of one path of said phase shift stages by means of Joule effect heating strips (L1 . . . L5) or by means of metallic field plates adapted to receive a signal suitable to modify the electric field intensity.

Abstract: Overlapped coupler combination Photonic Lightguide Circuits for routing optical signals within an optical communication system include at least two couplers whose planar slab waveguides are disposed in supportedly overlying relation so as to conserve wafer real estate. In a preferred form of the invention wherein a Dragone router is implemented, output waveguides of a first of the couplers are connected to the input waveguides of a second of the couplers at a predetermined angle so as to create path length differences in the individual optical signals traversing through the various waveguides. These path length differences ensure that the optical signals have good wavelength differentiation so that a large number of channels can be accommodated. The signals traverse through the couplers in uniform or non-uniform spaced channels of less than about 100 GHz, and more preferably less than about 25 GHz. The coupler combination devices are particularly useful as Dragone routers and other types of DWDM routers.

Abstract: A 1×N optical wavelength-division demultiplexer alignment apparatus including a 1×N optical wavelength-division demultiplexer including an input waveguide, N output waveguides and a plurality of alignment waveguides positioned around the input and output waveguides, for demultiplexing signal light and supplying the demultiplexed signal light to the N output waveguides if the signal light has a wavelength in a communication wavelength region, and for supplying the signal light to the alignment waveguides if the signal light has wavelengths outside the communication wavelength region. A single optical fiber block has a single optical fiber to transmit the signal light to the 1×N optical wavelength-division demultiplexer, a multiple optical fiber block having N optical fibers connected to output sides of the N waveguides and alignment optical fibers connected to output sides of the alignment waveguides.

Abstract: The present invention expands a selective wavelength band and flattens light intensity in the selective wavelength band as good as or better than prior art, and makes power loss less than prior art. The invention as a period characteristic wavelength splitter and an arrayed waveguide diffraction grating wavelength splitter between the first input/output port and the second input/output port in this sequence. The period characteristic wavelength splitter is comprised of the third star coupler, the second arrayed waveguide comprised of multiple waveguides having different optical path lengths, and the fourth star coupler. When an optical signal is input from the first input/output port, the period characteristic wavelength splitter outputs optical signals which wavelengths sequentially deviated with difference &dgr; from multiple ports at the first star coupler side of the fourth star coupler.

Abstract: A router combines free-space and guided wave optics to drastically increase the number of channels used in WDM transmission systems. The two-stage router uses the partial demultiplexing characteristic of an arrayed waveguide router (AWR) combined with a free-space optical router to fully demultiplex an input WDM signal. The two-stage router can be used to obtain output wavelength signals in either one- or two-dimensional arrays.

Abstract: An apparatus for optically generating chaotic random numbers to obtain chaotic random numbers satisfying a chaotic dynamical system expressed by X(n+1)=F(X(n)) includes an optical signal splitting device for splitting light from a light source into a predetermined number of beams with identical optical power; an optical chaotic signal generating device comprising the same number of interferometers as the beams, each having a pair of optical paths for receiving the beams from the optical signal splitting device, splitting each of the beams, interfering the splitted beams and outputting optical chaotic signals; optical path length difference data memory device for memorizing data on a difference between the lengths of the pair of optical paths at portions thereof between splitting and interfering; optical output signal measuring device for measuring optical power of the optical chaotic signals output from the interferometers as chaotic random numbers; and an optical output signal memory device for m

Abstract: An improved dense wavelength division multiplexer for the separation of optical channels is provided. The dense wavelength division multiplexer includes the inputting of an optical signal with the optical signal containing a plurality of optical channels; the separating of one or more of the plurality of optical channels from the optical signal using separators at least partly arranged in a multi-stage parallel cascade configuration; and the outputting of the separated plurality of channels along a plurality of optical paths. The dense wavelength division multiplexer of the present invention provides for a lower insertion loss by requiring an optical signal to travel through fewer optical components in the separation process.

Abstract: A strict-sense nonblocking N×N spatial optical cross connect that employs planar lightwave beam steerers. The beam steerers allow for a modular design without requiring two-dimensional chip-to-chip waveguide interconnections. The modular design and the fact that the number of electrical control leads scales as NlogN in turn allows the possibility of constructing large, robust, solid-state cross connects. A cascaded beam-steerer design that substantially relaxes phase shifter strength requirements is also described.

Abstract: This invention relates to a process for setting up several data paths on a single optical transmission fiber, including a modulation step consisting, for each data path, of modulating a light source with a specific wave length by signals corresponding to said data path, a step transmitting the modulated light signals to a mixer and a step of chromatically separating the light signals transmitted by the optical fiber, characterized in that the signals are multiplexed by an integrating sphere coated on the inside with a reflecting surface and including a plane reflector oriented perpendicular to the axis of the transmission optical fiber.

Abstract: An optical multiplexer/demultiplexer with an improved spectral characteristic is provided by two diffraction gratings (21, 20) arranged optically in tandem and one being configured to embrace the other, the gratings also being arranged to provide free spectral ranges differing by a factor of at least two, and having a coupling (22′) between them that carries over into the second grating information concerning the dispersion afforded by the first grating.

Abstract: A multi-branching optical coupler outputs input light by branching the input light into multiple fibers. This multi-branching optical coupler has a center fiber positioned at the center of the multiple fibers and multiple surrounding fibers installed around the circumference of the center fiber such that the distance between any two adjacent surrounding fibers is substantially constant. The light input to the input end of the center fiber is branched into the output end of the center fiber and the surrounding fibers. The center fiber has a core that extends from the input end to the output end, and a clad formed around the core. The totality of fibers has a coupled region in which all of the surrounding fibers are fused to the center fiber. The center fiber and the surrounding fibers may be installed substantially parallel to each other and linearly. As an alternative, the surrounding fibers may be twisted co-axially about the center fiber.

Abstract: A multichannel laser is based on an interleaved chirped waveguide grating router. An interferometric modulator is incorporated inside a laser cavity by means of a waveguide grating router and enables independent modulation of any of the wavelengths of the multichannel laser. The interferometric modulator operates independently of the wavelength selection elements of the waveguide grating router used to select the wavelengths of the multichannel laser.

Abstract: Optical fibers used in a star-type optical coupler each have a light signal input terminal and a light signal output terminal. A light signal passes through the optical fibers in a linear displacement. According to the present invention, linear displacement of the light is transformed into a generally circular movement through a coupling ring, such that the input terminals of the optical fibers need not be grouped on the same side of the optical fibers, and likewise for the output terminals of the optical fibers. Thus, the input terminal of a first optical fiber and the output terminal of a second optical fiber can be arranged adjacent to each other, so as to form a pair. When the input terminal is thus paired with the output terminal, the star-type optical coupler can be connected to peripheral optical communications apparatuses more easily.

Abstract: An add/drop filter for optical wave energy incorporates a Bragg grating in a very narrow waist region defined by merged lengths of elongated optical fibers. Light is propagated into the waist region via adiabatically tapered fibers and is transformed from two longitudinally adjacent fibers into two orthogonal modes within the air-glass waveguide of the waist and reflected off the grating from one fiber into the other. The geometry of the waist region is such that the reflected drop wavelength is polarization independent, without lossy peaks in the wavelength band of interest. Additionally, back reflection are shifted out of the wavelength band of interest. High strength gratings are written by photosensitizing the waist region fibers by constantly in-diffusing pressurized hydrogen or deuterium. For narrow spectral bandwidth gratings, dimensional variations must be minimized or compensated, and the grating is apodized by both a.c. and d.c. variations in writing beams at a net constant power.

Abstract: A wavelength division multiplexing device is disclosed. In a preferred embodiment, the wavelength division multiplexing device comprises a diffractive optic collimating lens for collimating a plurality of monochromatic optical beams, a diffraction grating for combining the plurality of collimated, monochromatic optical beams into a multiplexed, polychromatic optical beam, and a diffractive optic focusing lens for focusing the multiplexed, polychromatic optical beam.

Abstract: A duplicated-port waveguide grating router is provided that includes a first free space region configured to receive an optical signal from at least one input waveguide. An optical grating comprising a plurality of waveguides is connected to the first free space region. The optical grating is defined by a plurality of unequal length waveguides. Connected to the optical grating is a second free space region, A plurality of output waveguides are connected to the second free space region, wherein the plurality of output waveguides includes at least two adjacent waveguides having ends remote from the second free space region. A 2×2 coupler having two input ports connected to the remote ends of the two adjacent waveguides and two output ports, which are the output ports of the duplicated-port waveguide grating router. The duplicated-port waveguide grating router provides substantially identical specifiable passband and widths within the two output ports.

Abstract: The present invention provides a wavelength division multiplexing filter that requires lower costs, a smaller size, and a smaller amount of fiber routing operations. According to the present invention, a first module constitutes a first filter. A second module constituting a second filter is produced by connecting together circuits identical in number to a plurality of output ports of the first module, the circuits each comprising a combination of directional couplers and Bragg gratings both formed of silica-based-glass waveguides, the circuits each having a wavelength selection characteristic so as to correspond to each of the output ports. The second module is connected to the first module via an 8-fiber ribbon to simplify the integration and connection of the circuits.

Abstract: A wavelength router has a structure capable of preventing a wavelength shift from occurring and an optical circuit device capable of reducing a phase error. The wavelength router includes three input ports; three input waveguides each having one end connected to the corresponding input ports, respectively; a first plane waveguide to which other ends of the input waveguides are connected; three output ports; three output waveguides each having one end connected to the corresponding output ports, respectively; a second plane waveguide to which other ends of the output ports are connected; and five interconnecting waveguides for connecting an output end face of the first plane waveguide and an input end face of the second plane waveguide. To make lengths of the interconnecting waveguides equal, optical path lengths from connection portions (end face) into which light signals are input to coupling parts between the first plane waveguide and the interconnecting waveguides, respectively, differ from one another.

Abstract: An optical transmission equipment for use in an optical transmission system, having an optical amplifier (10A), comprising: a first optical doped fiber (1A); a second optical doped fiber (1B); a third optical doped fiber (1C); an optical isolator (6) of bringing loss in the optical signal, being provided between the first optical doped fiber and the second optical doped fiber; a dispersion compensator (7) being provided between the second optical doped fiber and the third optical doped fiber; and a pumping light source (2) being optically connected to so that the optical doped fibers (1A, 1B, 1C) are excited in common.

Abstract: A wavelength division multiplex transmission system has an optical fiber trunk (12) with one or more branching units (18) each providing an add/drop channel (22, 20). In the branch, components are provided for pre-dispersing the wavelength of the add channel, prior to route to the trunk (12), with a dispersion characteristic of opposite sign to the dispersion occurring in the trunk, thereby to compensate for dispersion of that wavelength occurring along the trunk.

Abstract: A multiplexer has an optical circulator including at least first, second and third circulator ports. An optical fiber with a first optical transmission path is coupled to the first circulator port of the optical circulator. The optical fiber carries a wavelength division multiplexed optical signal, including signals &lgr;1-&lgr;n, and at least one signal &lgr;1 to be dropped by the multiplexer. A second optical transmission path is in optical communication with the second circulator port. A first filter is coupled to the second optical transmission path. The first filter passes a portion of the &lgr;1 signal, and reflects a first residual &lgr;1 signal and signals &lgr;2-&lgr;n to the optical circulator. A third optical transmission path is in optical communication with the third circulator port and transmits the signals &lgr;2-&lgr;n received from the optical circulator.

Abstract: Plurality of channel waveguides of an arrayed waveguide diffraction grating are arranged such that all of intervals thereof are not constant between each two adjacent channel waveguides at a first coupling portion for coupling an input slub waveguide and the arrayed waveguide diffraction grating and a second coupling portion for coupling an output slub waveguide and the arrayed waveguide diffraction grating. Further, the plurality of channel waveguides of the arrayed waveguide diffraction grating are arranged such that all of length differences thereof are not constant between each two adjacent channel waveguides. For example, one of the channel waveguides is deleted, so that a length difference of adjacent channel waveguides is determined to be larger than that of the other two adjacent waveguides.

Abstract: An optical device includes a substrate formed of an electrooptic material, a waveguide formed in the substrate, an electrically conductive film formed over at least a portion of the waveguide and a source of DC voltage electrically connected to the film for thermally inducing a change in the optical refractive index of the substrate of the optical device.

Abstract: A dispersion slope compensator includes a dispersion compensation fiber, an optical circulator and a plurality of fiber gratings. The optical circulator is connected between an optical fiber and the dispersion compensation fiber for introducing mixed optical signals propagating in the optical fiber into the dispersion compensation fiber. The fiber gratings are provided at predetermined positions of the dispersion compensation fiber so as to respectively reflect the mixed optical signals back to the optical fiber through the optical circulator. Thus, accumulated dispersions of the mixed optical signals are fully compensated due to different propagating distances of each of the mixed optical signals in the dispersion compensation fiber.

Abstract: An optical apparatus is disclosed that includes a first Z×T optical switch having Z input ports and T output ports, where T is at least 2, optically coupled to an integrated optical generalized Mach-Zehnder interferometer. The result is an optical switch, which is operated using a smaller number of control elements and control levels than the generalized Mach-Zehnder interferometer alone.

Abstract: An optical coupler for coupling light along an axis between a light port on one side of the coupler and a plurality of light ports on another side of the coupler. The coupler comprises a one-side stage with a light port and a many-side stage with a plurality of arms situated about the axis, each having a light port. A midput region separates the one-side and many-side stages and is situated along the axis where the plurality of arms at least initially starts to split from each other in a direction towards the many-side light ports along the axis. Cross sections of each of the respective initial portions of the arms along the direction are arranged about the same distance from the axis. The cross sectional areas of the arms along the axis are larger at a break point region at which the arms fully separate from each other along the axis than at the many-side light ports. At least a pair of the arms each start to split along the direction in a substantially symmetrical manner about the axis.

Abstract: In an optic fiber, different first and second optical signals are transmitted through optic fiber in the first direction. The first optical signal may be infrared, whereas the second optical signal may be visible, so as to provide a visible indication that optical energy is propagating through the optic fiber. The optic fiber is connected to an optical system that includes a transceiving GRIN lens, a receiving GRIN lens and a plurality of transmitting GRIN lenses that are smaller than the receiving GRIN lens. The transceiving GRIN lens has opposite first and second ends, collimates optical signals propagating therethrough and emitted via the first end, and focuses optical signals propagating therethrough and emitted via the second end. The receiving GRIN lens has opposite first and second ends, and focuses optical signals propagating therethrough and emitted via the second end thereof.

Abstract: An optical device having an array of substantially equal-length optical waveguides. Each one of the optical waveguides includes one or more straight segments, one or more curved segments, and optionally, one or more transition segments. According to the invention, the sum of the lengths of the straight segments in each of the waveguides is substantially equal. Similarly, the sum of the lengths of the curved segments in each of the waveguides may be substantially equal as well. Finally, the sum of the lengths of optional transition segments in each of the waveguides may also be substantially equal. Advantageously, the device exhibits relative lengths that are robust to fabrication errors and have low polarization sensitivity.

Abstract: An optical star assembly having a ribbon fiber optic mixing element with the first and second ends. A first and second bundle of fiber optic cables are provided each with an engagement end for connection with a respective end of the ribbon fiber optic mixing element. The ribbon fiber optic mixing element and a portion of the fiber optic cables are carried in the housing so that the housing biases each end of the ribbon fiber optic mixing element towards an engagement end of the first and second bundles of fiber optic cables respectively. The fiber optic cables may be connected to a plurality of optical receivers so that the ribbon fiber optic mixing element distributes optical information from each of the fibers to all of the optical receivers in the assembly.

Abstract: In a waveguide grating router, a predetermined composite transmission spectrum output is achieved by eliminating loss imbalances through the use of variable loss elements. The variable loss elements are introduced to the waveguide grating router's waveguide ports, such that the loss of a transmitted signal is independent of wavelength. The waveguide grating router includes at least one input waveguide and a plurality of output waveguides. The variable loss element is introduced to a predetermined group of output waveguides to produce a predetermined composite amplitude spectrum of the output signals. To provide a predetermined composite amplitude output spectrum, the variable loss elements may be implemented in a variety of ways, including a method of varying the cross-sectional areas of the router's waveguide ports to introduce more loss.

Abstract: An optical transmission device which reduces optical noise in an optical transmission system. The optical transmission device includes a core light amplifying unit, and a first buffer light amplifying unit for amplifying a first signal light from a first transmission path and an amplified second signal light from the core light amplifying unit. The first buffer light amplifying unit supplies the core light amplifying unit with the first signal light, and supplies the first transmission path with the amplified second signal light. Also provided is a second buffer light amplifying unit for amplifying a second signal light from a second transmission path and an amplified first signal light from the core light amplifying unit. The second buffer light amplifying unit supplies the core light amplifying unit with the second signal light, and supplies the second transmission path with the amplified first signal light.

Abstract: A unidirectional or bidirectional node for use in an optical communications network, a network consisting of such nodes and a method of maintaining a target loss around a ring. The node comprises one or more optical couplers as well as either or both of drop circuitry connected to an output port and add circuitry connected to an input port. This allows for changes to the wavelength plan without interruption of the ring traffic. If add circuitry is used, the wavelengths in the filtered add signal should be distinct from those of the incoming signal on the main optical path which is merged with the add signal. When separate fibers are used for transmitting and receiving data between a hub and nodes in a ring, the through loss of the couplers is reduced for upstream couplers, which increases the available loss to be assigned to the fiber. The method of maintaining a target loss around a ring relies on the known through loss of the coupler at each node to set the gain of an amplifier connected to the node.

Abstract: A multi-wavelength optical cross-connect switch architecture incorporates a plurality of wavelength-selective optical cross-connect (WSXC) switch fabrics that receive multi-wavelength input signals distributed by one or more optical slicers and generate multi-wavelength output signals that are combined by a plurality of optical combiners. The WSXC fabrics employ fiber Bragg gratings (FBGs) as wavelength-selective elements. Using this architecture, the number of multi-wavelength channels carried by each WSXC is reduced from the number of channels present in each multi-wavelength input signal. In addition, the wavelength spacing between adjacent channels carried by each WSXC is increased over the spacing between adjacent channels in each multi-wavelength input signal.

Abstract: The present claimed invention improves on the conventional comb and multiple router approach by making multiple use of a single router by using interleaved groups of wavelengths that enter through different entrance ports and exit through different groups of exit ports of the same router. This permits better separation (lower crosstalk) between adjacent channels, greatly reduced temperature sensitivity, small physical size and lower cost. With these improvements, a large number of wavelength add/drop sites may be cascaded in WAD/WDM systems.

Abstract: A wideband polarization splitter and combiner is fabricated using either fiber coupler technology or planar coupler technology. The device splits or combines wideband light signals without losing a substantial amount of spectral information. An antipodal phase generator is used to split a randomly polarized light signal into relatively wideband polarization components for use by polarization sensitive devices. The optical device is fabricated using polarization preserving fibers or waveguides, but it is intended for use in systems employing non-polarization-preserving fibers. The polarization splitter/combiner is also used as the basis for an isolator/circulator and a polarization controller. The polarization controller converts a randomly polarized light signal into a signal having a known and definite state of polarization.

Abstract: A wavelength-dependent splitter/router is made by chirping a waveguide grating router, such that the path-length difference between pairs of adjacent grating arms is not a constant. With careful design, a device can be fabricated that acts as an optical splitter in one wavelength band and as an optical router in another wavelength band. The invention has applicability in optical networks, because it enables the overlaying of a wavelength-division-multiplexed (WDM) network (which relies on routers) with a broadcast type of network (which relies on splitters).

Abstract: The optical hold unit (100) of the present invention includes an optical modulator (108) that has an electrical input, an optical input, and an optical output. A 1.times.N optical splitter (106) is also provided that has an optical input and N optical outputs. In addition, N optical paths (112) are individually coupled to the N optical outputs and carry one of the N output signals. Each optical path has an associated propagation delay. Optical delay elements may be located in any of the N optical paths that carry the output signals. The optical delay elements serve to lengthen the propagation delay (114a-e) of the optical path (112a-e) in which the optical delay element is located. In an alternative embodiment, the optical hold unit (200) includes an optical modulator (108) that has an electrical input, an optical input, and an optical output. An optical resonator (202) is also provided and connected to the optical output of the modulator (108).

Abstract: An optical multiplexer/demultiplexer with an improved spectral characteristic is provided by two diffraction gratings (61, 60) arranged optically in tandem, the gratings being arranged to provide free spectral ranges differing by a factor of at least two, and having a coupling between them that carries over into the second grating information concerning the dispersion afforded by the first grating.

Abstract: The present invention teaches a novel technique for reducing the temperature-related spectrum shifts in optical devices, particularly waveguide grating routers (WGR). In general, the present invention modifies a portion of the length of at least one waveguide within an optical device in a manner that stabilizes the wavelength spectrum passing therethough even when exposed to temperature variations. More specifically, by knowing how the refractive index of a certain material changes with temperature variations as compared to that of common waveguide materials, such a silica, one may employ the teachings of the present invention to precisely modify the nature of the optical path through which a signal travels to fully compensate for any temperature-related wavelength spectrum shift. In other words, be able to produce an optical device with a plurality of waveguides each of which is appropriately modified so that any optical signal passing therethrough has the same wavelength at any two given temperatures.

Abstract: A sleeve for retaining a plurality of optical fibers in a close or contacting relationship is provided. The sleeve has a bore receiving a number of optical fibers. The internal surface of the bore is such that when that number of optical fibers are contained therein the bore surface defines a perimeter substantially equally spaced about the external surfaces of the optical fibers. Advantageously the sleeve of the present invention may be sealed about the plurality of fibers by vitrification or adhesive to support the fibers or fiber ends without causing unequally distributed stress in the fibers. Signal quality is thus better assured.

Abstract: The present invention relates to a multiplexer and/or demultiplexer optical component of the waveguide array spectrograph type, the component comprising an inlet coupler and an outlet coupler in a star configuration between which said array extends, the array having a first directed mean direction on departure of the waveguides of the array from the inlet coupler, and a second directed mean direction on arrival of the waveguides of the array at the outlet coupler, and presenting a directed general axis defined as being the axis passing through the centers of the couplers and on which a single positive direction is defined, and in which the first and second directed directions have respective directive angles measured algebraically from the general directed axis, which angles have the same sign.

Abstract: The present invention uses a light-pipe for beam splitting, combining, hybrid space-wavelength multiplexing, hybrid space-wavelength demultiplexing, dense wavelength division multiplexing, and dense wavelength division demultiplexing. A light-pipe has a first end where light enters the light-pipe and a second end where the light exits the light-pipe. The light-pipe is a polygonal rod or a hollow reflective cavity. To perform beam splitting, light enters the first end of the light-pipe and reflects off of the side surfaces inside the light-pipe producing additional light beams. By placing an imaging lens at the output end of the light-pipe, all of the virtual images (n-1) of the additional light beams and the original light entering the light-pipe become the object of the imaging lens. As a result, the light-pipe acts as a 1-to-n splitter.

Abstract: The present invention relates to an optical signal processing apparatus and optical signal processing method which enable generation, waveform shaping, waveform measurement, waveform recording, correlation processing, and the like of optical pulses of 1-10 ps. A basic construction of the optical signal processing apparatus includes an optical waveguide, a first structure for equally distributing output light of the optical waveguide, an optical waveguide comprising an aggregate of optical waveguides changing in optical length by a constant interval, a arrayed waveguide for dividing the output light, second structure for focusing optical output of the arrayed waveguide, and a mirror for receiving and reflecting incident light focused by the second structure.

Abstract: Optical devices, such as wavelength routers, having a plurality of waveguides of differing lengths, with improved independence to temperature fluctuations. Improved temperature independence is achieved by varying the cross-section of the device waveguides. Cross-section variation can be implemented in one or more of the following ways: selectively applying a temperature-compensating material (e.g., a polymer) over portions of the waveguides, and/or varying the dimensions and/or compositions of the materials used in the waveguides, either along each waveguide or between waveguides or both. By carefully designing the devices, the temperature effects resulting from the different lengths of the different waveguides can be compensated to produce a relatively temperature-independent device.

Abstract: A wavelength division multiplex branching unit for an optical fibre transmission network comprises a branching unit housing (100) and means (102) external to the housing for permitting the connection of one or more wavelength selective devices (A, B, C, D) to a trunk transmission fibre. The wavelength selective devices are each responsive to a different transmission wavelength and are effective to direct transmission signals have that response wavelength from the trunk fibre to a spur fibre of the branch cable.

Abstract: An optical multiplexer is formed that overcomes the polarization dependence of conventional DWDM routers and is also significantly smaller than prior art routers. A reflective router is formed that utilizes one-half of a star coupler, with a reflective surface formed along the planar face of the coupler so as to form a "folded" arrangement. First and second waveguide arrays are coupled to opposing quadrants of the folded coupler, with the reflective surface providing the coupling therebetween. A quarter wave plate (or Faraday rotator) and reflective surface are disposed at the output of the second waveguide array and are used to provide a TE/TM mode conversion to the optical signals exiting the second array (thereby canceling out any polarization-dependent effects). The reflective surface beyond the quarter wave plate re-directs the optical signal back through the second waveguide array. The signal will then again reflect through the folded coupler and exit the multiplexer through the first waveguide array.