Abstract: An optical structure for combining light from a plurality of individual optical fibers into a single optical transmission device. The structure can be incorporated into the optical probe of a spectrophotometric instrument and includes a plurality of optical send fibers having input and output ends and an optical light mixer having input and output ends. The output ends of the send fibers are secured in optical communication with the input end of the light mixer.

Abstract: An arrayed waveguide element having flat optical frequency characteristics, and an optical communication system using such arrayed waveguide element are realized by providing the arrayed waveguide element that is prepared by forming an inputting channel waveguide as well as an outputting channel waveguide, a channel waveguide array, a first sector form slab waveguide for connecting the inputting channel waveguide with the channel waveguide array, and a second sector form slab waveguide for connecting the outputting channel waveguide with the channel waveguide array on a substrate. A waveguide part wherein the outputting channel waveguide is connected with the second sector form slab waveguide is defined in a parabolic configuration, whereby flat optical frequency characteristics are realized. Furthermore, it is possible that an individual parabolic configuration is adjusted in response to a wavelength, so that it can cope with a trend of broad band in optical signals.

Abstract: A waveguide device has an input waveguide, a plurality of output waveguides, a channel waveguide array, an input slab waveguide, and an output slab waveguide. The output slab waveguide connects an output end of the channel waveguide array to the output waveguide, and has optical input/output characteristics set to given ratios for the output waveguides with respect to the input waveguides. The waveguide device is capable of adjusting signal levels output from the respective waveguides without the need for circuit parts for compensating for loss differences and also the need for a process of highly accurately attaching parts.

Abstract: A method of cross-connecting or reorganizing individual optical fibers of a plurality of fiber optic ribbons include the steps of providing a substrate having an adhesive thereon with a mixing zone within the boundaries thereof. A plurality of individual optical fibers are routed onto the substrate to form a plurality of fiber optic input ribbons, reorganizing the fibers in the mixing zone, and forming a plurality of fiber optic output ribbons. At least some of the output ribbons have fibers from more than one of the input ribbons. The input and output ribbons are coated on the substrate outside the mixing zone to hold the routed fibers in ribbon form, leaving at least portions of the fibers in the mixing zone uncoated. The coated ribbons are stripped from the substrate with the uncoated fibers from the mixing zone being loose. A holding device is placed about at least the uncoated loose fibers between the input and output ribbons.

Abstract: An optical coupler 10 comprising at least three fibres 12, 14 and 16, portions of the fibres being fused to each other to form a coupling region 30 operable to couple light therebetween. At least two of the fibres have inputs 18 and/or 20 and/or 22 and at least two of the fibres have outputs 24 and/or 26 and/or 28. In use, on illumination of at least two of the inputs light intensity is emitted from a plurality of the outputs having a substantially asymmetric phase relationship, such as, for example, a quadrature phase relationship between two of the outputs. The invention also provides for methods of making such a device.

Abstract: A fiber connecting method and a laser apparatus using the fiber connecting method are disclosed. A plurality of fibers are bundled into a fiber bundle. The ends of the plurality of the fibers are connected to an end of a single-core fiber having a larger core diameter than the plurality of the fibers. The plurality of the fibers have different directions and characteristics depending on the position connected to the single-core fiber.

Abstract: An apparatus for optical coupling having a first array of individual waveguides optically communicating with a free space region at a first junction and each waveguide having a tapered region proximate the junction where a gap spacing between tapered regions of adjacent individual waveguides is substantially constant is proposed. The gap spacing is a minimum amount of space between adjacent individual waveguides. The first array of individual waveguides also has a horn region immediately proximate the tapered region and opposite the first junction with an increasing width whose maximum establishes the gap spacing.

Abstract: An arrayed waveguide grating type optical multiplexer/demultiplexer in which the 1 dB band width is large, the ripple is small, and the degradation of the adjacent crosstalk can be controlled. A waveguide forming portion is formed on a substrate. The waveguide forming portion includes an optical input waveguides, a first slab waveguide, an arrayed waveguide including a plurality of channel waveguides arranged side by side and which have different lengths with the differences preset, a second slab waveguide, and a plurality of optical output waveguides arranged side by side, all of the components being connected in the order stated. A single mode straight waveguide narrower than the optical input waveguides is provided at the output end of at least one or more optical input waveguides. A multi-mode trapezoidal waveguide whose width increases toward the arrayed waveguide is provided at the output end of the straight waveguide.

Abstract: At least one of two slab waveguides constituting an arrayed waveguide grating is cut and separated together with a substrate on a cross separating face. A slide moving member is arranged over a waveguide forming area formed on the substrate including the separating slab waveguide and a waveguide forming area formed on the substrate including the separating slab waveguide. Temperature dependence of the center wavelength of the arrayed waveguide grating is reduced by slide-moving the separating slab waveguide by the slide moving member along the cross separating face dependently on temperature. The shift of an initial center wavelength is corrected by plastically deforming the slide moving member so that the initial center wavelength is conformed to a grid wavelength.

Abstract: A method of assembly is presented for a multi-wavelength optical monitor (MWOM) for use in fibre optic telecommunication networks. The method allows coarse optimisation to be used to align an input optical fibre and detector array relative to a wavelength division demultiplexing element. The detector array output data are transformed with a digital signal processor into relative intensities of the components of the spectrum or spectral parameters of telecommunication channels.

Abstract: An efficient tapered optical fiber bundle along with the method of manufacturing is presented. The tapered fiber bundle is fully fused to an induced shape with no interstitial space between fibers. To minimize fiber deformation and hence the tapered bundle's loss, the individual fibers are minimally deformed by positioning them in a fixture with predetermined geometry prior to fusion. The bundle could be optionally reshaped after fusion. The tapered bundle could then be used in its original form as a star coupler, or it could be cleaved and coupled to a multimode fiber, a multi-clad fiber, a cladding-pumped fiber, or an optical system to form an optical device. The resulting optical device has improved efficiency and lower loss compared with prior art devices.

Abstract: A switching apparatus provides 1×2 and 2×2 switching functions having significantly reduced crosstalk levels using an imaging arrangement of three arms combined with two star couplers. In another 1×2 switching element embodiment, the input star coupler is replaced with an optical signal splitter. Application of the 1×2 and 2×2 switching elements include the realization of a variety of dilated N×N broadband switches with negligible crosstalk over very wide wavelength stopband characterized by two or more equally spaced zeros. The very wide crosstalk stopband enables the N×N broadband switch to switch a broadband wavelength division multiplexed input signal to the desired output port with very low crosstalk at the other output ports.

Abstract: The present invention aims at providing a wavelength multiplexing/demultiplexing apparatus for reducing a loss at a portion where an input slab and channel waveguides are connected with each other, thereby capable of realizing the reduction of loss in the overall apparatus. In order to achieve the above object, in this wavelength multiplexing/demultiplexing apparatus comprising an input waveguide, an input slab, channel waveguides, an output slab and output waveguides that are formed on a substrate, a curvature radius (r1) of an output side circular arc interface of the input slab is smaller than a curvature radius (r2) of an input side circular arc interface of the output slab, and spacing (P1) between the channel waveguides at a portion where the input slab and each of the channel waveguides are connected with each other is smaller than spacing (P2) between the channel waveguides at a portion where each of the channel waveguides and the output slab are connected with each other.

Abstract: An all optical transparent network is arranged such that each optical communication port can simultaneously and independently broadcast optical signals to, and receive optical signals from, any or all other optical communication ports on the network, and such that optical communications ports can arbitrarily and conveniently be added at distributed locations. The optical network constructed of paired 2×2 optical couplers that are cross-connected in a unique manner to form twin couplers, and/or N×N star couplers having at least one paired receiving and transmitting port such that each of the N communication ports communicates directly with each of the other communication ports.

Abstract: An optical multiplexer/demultiplexer having a small-loss structure that uses an arrayed waveguide grating to optimally make the passband characteristic of demultiplexed light flat. An optical input waveguide and a sector slab waveguide are connected by a directional coupler. The directional coupler comprises a central waveguide including an end portion on the output side of the optical input waveguide and arranged waveguides which are arranged on both sides of the central waveguide and the exits of which are connected to the sector slab waveguide. A taper is formed on both side portions of the central waveguide so that the width of a core will gradually narrow in the direction of the exit, and the central waveguide is located so that this end portion will not touch the sector slab waveguide. The width of a core in each of the arranged waveguides is uniform.

Abstract: An optical interleaving switching method and apparatus. In one aspect of the present invention, the disclosed apparatus includes first and second multi-mode interference (MMI) coupling devices disposed in a semiconductor substrate. Each of the first and second MMI coupling devices include first and second inputs and first and second outputs. A first optical coupler having a first optical path length is included. The first output of the first MMI coupling device is optically coupled to the first input of the second MMI coupling device through the first optical coupler. A second optical coupler having a second optical path length is also included. The second output of the first MMI coupling device is optically coupled to the second input of the second MMI coupling device through the second optical coupler. The first optical path length of the first optical coupler is different than the second optical path length of the second optical coupler.

Abstract: The invention pertains to an optical coupler comprising at least one input waveguide, a coupling region, and a plurality of output waveguides. The coupling region comprises a plurality of coupled waveguides, which diverge with respect to each other in the propagation direction of electromagnetic radiation launched in the said input waveguide. In these couplers, both the amplitude distribution and a phase distribution can be accurately matched the output waveguides resulting in relatively low loss and cross-talk.

Abstract: A fiber optic apparatus formed by fusing together multiple optical fibers and stretching the fused optical fibers to form a tapered portion. The tapered portion is cleaved or cut and polished to form a facet at which an optical beam is received or transmitted.

Abstract: In a star coupler, a Free Propagation Region (FPR) is bounded by a first interface and a second opposing interface, and guides an input signal launched from the first interface in a predetermined first plane while allowing the input signal to travel unguided in a predetermined second plane in the FPR which is orthogonal to the first plane. A plurality of output waveguides are formed in an array and terminate at the second interface of the FPR. The axis of each output waveguide at the second interface is separated from an axis of an adjacent output waveguide by a predetermined distance “t”. An input waveguide is split into a plurality of subsections which each terminate at the first interface of the FPR. The subsections of the input waveguide are arranged for simultaneously launching parts of the input signal into the FPR which diffracts and produces mode patterns at the second interface having a maximum intensity at inputs of each of the output waveguides, and a low intensity elsewhere.

Abstract: A folded optical waveguide structure comprises a substrate supporting a waveguide slab. An array of laterally spaced grating waveguides extends from the slab along the substrate to propagate optical signals to and from a reflective surface of a mirror member at an end face of the substrate. A layer of index matching material is located between the ends of the waveguides and the reflective surface. A thermally conductive, e.g. copper, body is interposed between the mirror member and the substrate such that dimensional changes of the thermally conductive body resulting from changes in ambient temperature of the grating array waveguides, tilt the mirror member against the substrate, away from or toward the end face of the substrate.

Abstract: An optical circuit device makes lightwaves respectively having different wavelengths fall on a filter at different incident angles, respectively. The optical circuit device includes a filter, a mirror and a planar lightwave circuit provided with grooves holding the filter and the mirror therein, and an optical waveguide. The optical waveguide has a receiving part that guides a lightwave to the filter, a multipath reflection part in which the lightwave is reflected repeatedly, and an emitting part that guides lightwaves transmitted by the filter to an emitting end surface. The lightwave falls on the filter at least at two incident angles. The multipath reflection part is provided with a bend waveguide. The filter and the mirror are disposed substantially parallel to each other.

Abstract: An arrayed waveguide grating including at least one first optical waveguide, a first slab waveguide, an arrayed waveguide, a second slab waveguide and a plurality of second optical waveguides. The arrayed waveguide is connected to the first optical waveguide via the first slab waveguide. The arrayed waveguide includes a plurality of channel waveguides each of which has a different length. The plurality of second optical waveguides are connected to the arrayed waveguide via the second slab waveguide. A number of the plurality of channel waveguides is determined such that a crosstalk is at most a predetermined value.

Abstract: An optical integrated circuit (OIC) or optical apparatus upon which a waveguide-grating router (WGR) device is fashioned is provided, where the circuit is configured to optimize a passband for each channel transmitted on an output waveguide. The WGR has two or more waveguides of varying widths optically coupled to a slab waveguide. The widths can be configured to facilitate producing a substantially uniform frequency-limited bandwidth, a substantially uniform wavelength-limited bandwidth, a substantially uniform isolation value, and/or a substantially uniform value for insertion loss between the output waveguides, which in turn facilitates producing optical data communication devices with more consistent transmission parameters and higher quality. In addition to various widths, the shape of the delivering end of a slab waveguide can be fashioned to further improve the consistency and quality of such parameters.

Abstract: An optical structure for combining light from a plurality of individual optical fibers into a single optical transmission device. The structure can be incorporated into the optical probe of a spectrophotometric instrument and includes a plurality of optical send fibers having input and output ends and an optical light mixer having input and output ends. The output ends of the send fibers are secured in optical communication with the input end of the light mixer.

Abstract: In a device for generating a quadrangular illuminating field, having a light mixing rod, which has a quadrangular cross-section as well as a quadrangular inlet area and a quadrangular outlet area and guides light coupled in via the inlet area to the outlet area, in order to generate therein the quadrangular illuminating field, the outlet area is limited by four rectilinear sides, of which two each meet in one of the corners of the outlet area at an angle which is not equal to 90°.

Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer includes an arrayed waveguide connected to at least one first optical waveguide via a first slab waveguide, a plurality of second optical waveguides connected to the arrayed waveguide via a second slab waveguide. At least one multi-mode waveguide has a first end portion and a second end portion having a second width larger than a first width of the first end portion. The first end portion of each of the at least one multi-mode waveguide is connected to each of the at least one first optical waveguide. The second end portion of each of the at least one multi-mode waveguide is connected to the first slab waveguide. A width of the at least one multi-mode waveguide increases from the first end portion toward the second end portion and is configured to realize multi-mode.

Abstract: A compact and multiple optical fiber coupler in which plural fused-tapered coupler portions 13-1 and 13-2, which have plural optical fibers 11a-1, 11b-1, 11a-2 and 11b-2 to form optical couplers, are formed side by side on a common substrate 15 and the fused-tapered coupler portions formed integral with the substrate 15 are enclosed in a package 160.

Abstract: An optical component is disclosed. The optical component includes an input waveguide having an expansion region expanding from an input port to a multimode port. The expansion region is configured to receive a light signal through the input port. An array waveguide grating is configured to receive a light signal from the expansion region of the input waveguide. An output waveguide has an output port configured to receive the light signal from the array waveguide grating. The output port has dimensions that are different from dimensions of the input port. In some instances, a function expressing the expansion from the input port to the multimode port includes an exponential function and/or a sinh function.

Abstract: A planar lightwave circuit includes an arrayed waveguide grating (AWG), with input and output waveguides, partially curved array waveguides with respective length differences, and planar waveguide regions for focusing optical energy between the input/output and array waveguides. Optimal waveguide widths and spacing along the planar waveguide region facets are disclosed, which are largely determinative of AWG size and optical performance. Also disclosed are optimal cross-sectional waveguide dimensions (e.g., width and height); modified index of refraction difference between the waveguide core and cladding regions; and optimal array waveguide lengths, path length differences, and free spectral range. These features, especially when combined with advanced fiber attachment, passivation and packaging techniques, result in high-yield, high-performance AWGs (both gaussian and flattop versions).

Abstract: An optical circuit comprises: (a) a body having an x and y axis and two sides substantially parallel to the y-axis and separated along the x-axis; (b) a plurality of first ports along one of the two sides, each first port comprising a number of substantially paralleled fibers; and (c) a plurality of second ports along the other of the two sides, each second port comprising a number of substantially parallel fibers. The ports are interconnected with the fibers such that (i) the fibers of a given second port comprise a fiber from each of the first ports, and (ii) the fibers interconnecting the first and second ports are arranged asymmetrically about at least one of the x or y axes.

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: 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: An arrayed waveguide grating type optical multiplexer/demultiplexer of the invention eliminates the temperature dependency of the light transmission center wavelengths and suppresses an increase in insertion loss with a simple configuration even under the conditions of high temperature and high humidity. A waveguide forming area comprising an optical input waveguide, a first slab waveguide, an arrayed waveguide formed of a plurality of channel waveguides arranged side by side having a different length each other, and a plurality of optical output waveguides connected one by one is formed on a substrate. For example, the first slab waveguide is separated at crossed separation planes that cross the path of light passing through the first slab waveguide. On the crossed separation planes, a matching grease is applied. A thin film member for covering the area arranged with the matching grease is disposed to suppress the evaporation of the matching grease.

Abstract: Techniques and designs for producing tunable optical dispersion by using two fiber Bragg gratings with nonlinear group delays to sequentially reflect an input optical signal and by tuning at least one of the fiber Bragg gratings.

Abstract: To provide a waveguide-arrayed optical wavelength multiplexer/demultiplexer in which a mode configuration of a waveguide slab output part is matched to a mode configuration of waveguide array input parts, to achieve a reduced loss irrespective of distances between arrayed waveguides, and a manufacturing method of the same, a wavelength multiplexer/demultiplexer (10) is formed on a substrate (11) with a plurality of input waveguides (12) for inputting wavelength division multiplexed optical signals, an output waveguide (13) for combining the wavelength division multiplexed optical signals to be output, a waveguide array (15) as a set of arrayed waveguides (15b) having predetermined waveguide length differences (&Dgr;L), an input waveguide slab (14) for interconnecting the plurality of input waveguides (12) and the waveguide array (15), and an output waveguide slab (17) for interconnecting the waveguide array (15) and the output waveguide (13), and the input waveguide slab (14) and the output waveguide slab (17

Abstract: An optical waveguide device comprises an input waveguide for converting incident light into a single optical mode, a plurality of output waveguides for splitting power of incident light and outputting it, and a tapered waveguide for connecting the input waveguide and the output waveguides, gradually increasing in width from the input waveguide toward the output waveguides, and the tapered waveguide has a non-adiabatic state, that is, a sufficiently large taper angle such that lower order optical modes couple into higher order optical modes while light propagates along the tapered waveguide.

Abstract: An optical amplifier is constituted by a planar waveguide having an optical core intersected by a transverse trench occupied by a polymeric optically amplifying medium. An optical pump for the amplifier is provided by a laser diode positioned to direct its emission, transversely with respect to the waveguide axis, into the polymer.

Abstract: A method of cross-connecting or reorganizing individual optical fibers of a plurality of fiber optic ribbons include the steps of providing a substrate having an adhesive thereon with a mixing zone within the boundaries thereof. A plurality of individual optical fibers are routed onto the substrate to form a plurality of fiber optic input ribbons, reorganizing the fibers in the mixing zone, and forming a plurality of fiber optic output ribbons. At least some of the output ribbons have fibers from more than one of the input ribbons. The input and output ribbons are coated on the substrate outside the mixing zone to hold the routed fibers in ribbon form, leaving at least portions of the fibers in the mixing zone uncoated. The coated ribbons are stripped from the substrate with the uncoated fibers from the mixing zone being loose. A holding device is placed about at least the uncoated loose fibers between the input and output ribbons.

Abstract: An optical device for receiving an optical signal of one or more wavelengths comprises an n-way optical coupler, where n is any integer ≧2, to split the optical signal by an intensity ratio into n branch signals. The device also comprises an arrayed waveguide grating, which includes a first optical slab having n input ports, where each branch signal is coupled to a different input port and a waveguide array structure including a plurality of waveguides. The waveguides have incrementally different path lengths. The device further comprises a second optical slab coupled to each of the plurality of waveguides of the waveguide array structure. In the second optical slab, the n branch signals are each demultiplexed. With this configuration, the demultiplexed signals of each branch signal do not substantially overlap with the demultiplexed signals of another branch signal at an output face of the second optical slab.

Abstract: In a light mixing rod comprising an inlet area and an outlet area, which guides light coupled in via the inlet area along a light guiding direction to the outlet area, two mixing rod portions are provided, which are successively arranged in the light guiding direction and optically coupled with each other, a first of which is in the form of a hollow portion into which the second mixing rod portion extends at least partially.

Abstract: An arrayed waveguide device has an expansion rod for adjusting a position of the optical paths at a star coupler, by thermal expansion, to compensate for wavelength response dependence on temperature. A bearing surface parallel to a plane of the waveguides prevents movement out of the plane and allow movement along the bearing surface parallel to the plane. Thus small lateral movements can occur accurately without introducing losses through unwanted vertical movements using a passive mechanical arrangement. It a be used together with active thermal control, to give better compensating accuracy, or compensation for manufacturing variations. An optical component assembly has a substrate having one or more mating profiles, and first and second planar waveguide chips having mating profiles. During assembly, the mating profiles enable passive alignment of an optical coupling between is respective waveguides of the chips. A groove locates a fiber on the chip using passive alignment.

Abstract: An optical waveguide circuit is provided that can reduce or eliminate polarization dependence by reducing or eliminating birefringence. A substrate consists of a silicon substrate, and a cladding and a core are composed of silica-based glass. The core has a multilayer structure composed of a few types of layers with different refractive indices such as first core layers and second core layers stacked in the direction parallel to the substrate. As for the birefringence of the waveguide, the geometrical birefringence caused by the multilayer structure is canceled out by the other birefringence, thereby being able to reduce or eliminate the birefringence of the waveguide.

Abstract: Optical amplifiers and other optical network equipment for handling optical data signals in fiber-optic communications links are provided. Optical fiber that is pumped by laser diode pumps may be used to provide optical gain. A circulator may be used in an amplifier to direct the optical data signals through a double-pass portion of the amplifier. A reflector at the end of the double-pass portion of the amplifier may direct forward-propagating optical data signals from the circulator in the backwards direction. Optical components such as spectral filters, and attenuators, gain stages, access ports, and other components may be located in the double-pass portion. A control unit may be used to suppress gain transients in the double-pass portion.

Abstract: The present invention relates to an optical multiplexer/demultiplexer comprising a structure for effectively lowering the crosstalk between adjacent signal channels, thereby realizing excellent wavelength multi/demultiplexing characteristics. The optical multiplexer/demultiplexer is designed such that, while adjacent channel waveguides are allowed to have optical path length differences different from each other, effective optical path length differences become constant between optical paths traveling by way of the channel waveguides adjacent each other in optical paths including slab waveguides as a whole, whereby the structure for connecting channel waveguides to flat connecting end faces of slab waveguides can be changed arbitrarily without being restricted by multi/demultiplexing conditions.

Abstract: An arrayed waveguide grating [WDG] comprises I/O slabs (53a, 53b) interconnected by a grating region (51). The grating region (51) comprises many, e.g. at least 25 and preferably 50 to 500, individual cores (61,62,63), which have different lengths so as to provide wavelength selectivity by causing phase changes in light conveyed between the I/O slabs (53a, 53b). There are bends (64) for providing the different lengths and, to improve optical guidance round the bends, empty (R.I.=1) grooves (71) are located adjacent to the inside (71.1) and outside radii (71.2) so that the evanescent fields extend into the grooves (71). In order to keep the dimensions small, which improves the optical accuracy, tight bends (preferred radii of curvature of less than 2 mm and especially less than 500 &mgr;m) are desirable. The grooves conveniently have tapered ends and they extend into straight portions adjacent to the bends.

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: An optical apparatus and method establishes a value of group velocity dispersion in wavelength division multiplexing applications. The optical apparatus includes at least one input waveguide, a first slab waveguide, an arrayed waveguide grating, a second slab waveguide, at least one output waveguide, and at least one transition segment optically connecting the at least one input waveguide to the first slab waveguide. The transition segment features a taper and an extension. The wide end of the taper is optically connected to the first end of the extension and the second end of the extension is optically connected to the slab waveguide and the first and second ends are equal in width. The extension may have a constant or non-constant width and may include a heating element. When a plurality of transition segments are featured, each transition segment may have similar or different properties. The transition segments may be used at the output side of the optical apparatus as well as at the input side.

Abstract: An optical waveguide device comprising a free space region, suitably provided by a slab waveguide, having optical signal ports for coupling to input and output waveguide sections and an optical waveguide grating including an array of grating waveguides coupling the free space region to a reflector surface to provide a folded structure. Dielectric waveguide structures are preferred. The grating includes tapered optical waveguide sections laterally spaced and optically isolated from each other which extend from the free space region, with the grating waveguides continuing as extensions of the tapered waveguide sections. Each of the grating waveguides differs in length from a neighboring grating waveguide by a constant increment, preferably an optical path length increment.

Abstract: The limitation of N in an N×N Wavelength Grating Router (WGR) is determined to be because of the intrinsic diffraction characteristics of the grating that occurs when N approaches the diffraction order m at which the grating operates. The N in a N×N WGR device is maximized for input signal channels equally spaced either in frequency or in wavelength. For the wavelength case, N is increased by appropriate changes in the spacing of the output ports of the WGR and/or by slightly correcting the by channels wavelengths.

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°.