Abstract: A Mach Zehnder (MZ) modulator with improved coupling of input and output fibers is provided. The MZ modulator combines the advantages of weakly guided input sections with strongly guided sections to optimize the coupling efficiency and selectivity of the device. Improved coupling between weakly and strongly guided sections of waveguide is provided by an intermediate tapered waveguide section which provides gradually changing mode confinement, which reduces the mode mismatch loss and therefore suppresses the reflection at the junction between the weakly and strongly guided sections of the waveguide.

Abstract: The integrated multimode optical coupling apparatus comprises an N-to-M optical coupling arrangement that is simple to manufacture, minimizes optical losses and is significantly less expensive than the prior art arrangements of coupling optical signals. The preferred embodiment of the apparatus of the present invention comprises a substrate into which is formed a plurality of optical channels, each of which is joined at one end into a single output optical channel. This integrated optical coupler is formed by diffusing silver ions or other equivalent ions into the glass substrate in these defined areas to form channels of high optical refractive index in the body of the substrate. At one end of each of the optical channels that are formed in the substrate, the plurality of the optical channels are joined together in a volumetric region of the substrate wherein the individual channels merge into one unified common structure.

Abstract: An optical fiber path joint member according to the present invention includes a main path having an inlet and an outlet at respective ends thereof; and at least one joint path joining to the main path in one direction at an angle of equal to or less than 45.degree.. A method of blowing an optical fiber is comprised of the step of blowing an optical fiber into a pipe through the optical fiber path joint member according to the present invention.

Abstract: A power monitoring system including a vertical cavity surface emitting laser generating an emission. A beam splitter optically positioned to receive the emission and split the emission into a first portion and a second portion. A monitor optically positioned to receive the first portion of the emission. An output of the monitor is used to control emissions of the vertical cavity surface emitting lasers.

Abstract: The present invention proposes an optical wavelength division multiplexer device which has low through loss and low reflection loss, and also has high isolation. A filter member is made up from a filter base board upon which is formed a wavelength division filter 5, and is disposed so as to intersect an input and output optical waveguide 3 of rectilinear form part-way along it at an intersection angle .alpha.. When light which includes light of two different wavelengths .lambda..sub.1 and .lambda..sub.2 is incident through an incident light side of the input and output optical waveguide 3, the light of wavelength .lambda..sub.2 passes through the wavelength division filter 5 and is emitted through an emitted light side, while the light of wavelength .lambda..sub.1 is reflected by the wavelength division filter 5 in a direction separated from the input and output optical waveguide 3.

Abstract: An optical switch network which includes a plurality N of cascaded optical switching stages, each mth one of the switching stages including 2.sup.m-1 Mach-Zehnder interferometers, where m=1 through N. The input port of the Mach-Zehnder interferometer of a first one of the optical switching stages receives an optical input signal, and the 2.sup.N-1 Mach-Zehnder interferometers of the Nth one of the optical switching stages provide a total of 2.sup.N output ports. Each of the Mach-Zehnder interferometers is preferably an unbalanced Mach-Zehnder interferometer, and the optical input signal preferably has a wavelength which is a selected one of 2.sup.N selectable wavelengths. The plurality N of cascaded optical switching stages provide 2.sup.N possible optical paths, whereby the optical input signal is automatically routed along a selected one of the 2.sup.N possible optical paths in dependence upon its selected wavelength.

Abstract: An optical coupling device for a node in a self-healing optical network, wherein the number of switching elements is reduced by using a novel type of optical 2.times.2-switch. The switch has two switching states: (i) a bar state (ss1) in which a first and a second main port are optically coupled through to a first and a second secondary port, respectively; and (ii) a half-cross state (ss2) in which the main ports are coupled through to one another and in which the secondary ports are not involved in any through-coupling. An integrated design of the switch is based on two asymmetric Y-junctions coupled to one another via a common side branch in which electrodes are active in order to vary the propagation constant. Accordingly, a compact, integrated version of the optical coupling device with only two switching elements can be achieved.

Abstract: A transition waveguide is provided between one main waveguide and two branching waveguides. The transition waveguide includes a stepped portion, of which the waveguide width suddenly slightly spreads stepwise with respect to the distal end portion of the main waveguide, and an extension portion extending from the stepped portion toward the branching waveguides. The waveguide width of the extension portion is substantially fixed or gradually increased in a region ranging from the stepped portion to the branching waveguides.

Abstract: Disclosed is an optical switch, which has: a substrate with electrooptic effect, wherein the substrate is provided with an incident-light waveguide, a tapered optical waveguide with a taper angle of .theta.1 which is connected to the incident-light waveguide and two arm optical waveguides with an aperture angle of .theta.2 therebetween which is connected to the tapered optical waveguide, the incident-light waveguide, the tapered optical waveguide and the two arm optical waveguides are formed on the substrate; and a plurality of control electrodes which are formed on the substrate; wherein the arm optical waveguides have a center-to-center interval of a value predetermined times a width of the arm optical waveguide at their ends where the arm optical waveguides is connected to the tapered optical waveguide, and the taper angle .theta.1 is greater than the aperture angle .theta.2.

Abstract: An intensity modulator having a Mach-Zehnder structure with first and second waveguide arms formed of an electro-optic polymer. The active molecules of the waveguide arms are poled in first and second different and substantially orthogonal directions. Electrodes are arranged to receive a modulating voltage and generate first and second electric fields which are respectively aligned with the first and second directions. As a consequence, the modulation depth of an optical signal which is transmitted through the modulator is substantially insensitive to the polarization of the signal. Other embodiments combine mode splitters and combiners with first and second Mach-Zehnder modulators which have electro-optic polymer waveguides. The active molecules of the arms of the two Mach-Zehnder modulators are poled in orthogonal directions.

Abstract: This invention relates to a novel design for a low-loss optical power splitter, in particular Y-branch types resulting from chemical vapor deposition (CVD) fabricated silica waveguides. More specifically, the present invention utilizes mode matching of the fundamental modes between the input and the output waveguides of a splitter to optimize the splitters operational performance. The optical power splitter of the present invention comprising an input waveguide region having a predetermined width (W) and capable of transmitting optical energy having a fundamental mode E.sub.1.sup.0. Additionally, the splitter includes at least two output waveguide regions positioned to receive at least a portion the optical energy from the input waveguide region wherein the output waveguide regions each have predetermined widths (w) and are capable of transmitting optical energy having a fundamental mode E.sub.2.sup.

Abstract: The present invention relates to an optical waveguide device, particularly a structure for positioning end faces of an optical waveguide and end faces of optical fibers with respect to each other, as well as a method of realizing such a structure. V grooves for positioning optical fibers are formed on a glass substrate by hot pressing, and the optical fibers are put in the V grooves to position end faces of the optical fibers and end faces of an optical waveguide with respect to each other, thereby forming the optical waveguide device of the invention.

Abstract: An optical module for interconnecting two or more optical fibers has a microreplicated waveguide element which is integrally formed on the same substrate with a splice element. In one embodiment, the module has three plates, a bottom plate, a cover plate, and a top plate, all contained within a common housing. The bottom plate has fiber-receiving grooves and fiber alignment grooves at its ends, the fiber alignment grooves being aligned with waveguide channels formed on the central portion of the bottom plate. The cover plate is used when forming the cores of the waveguide channels, to force residual curable, waveguide material into flow channels adjacent the waveguide channels, and this material, when cured, adheres the bottom and cover plates together. The top plate is used to clamp fibers which are held in the fiber alignment grooves, with the center of the fibers aligned with the core of the waveguide channels.

Abstract: The present invention relates to a fanout device for separating and encapsulating glass fibers of a multi-fiber cable. The invention also relates to a method of manufacturing a fanout device. A multi-fiber cable from which part of the sheath (1, 21) has been removed is placed in a jig (5) with the glass fibers (3, 24) mutually separated in an optical coupling device and with one end of respective fibers encapsulated in a respective glass tube (8, 20). The inventive fanout is comprised of two plates (9, 10, 22, 23) provided on one side with an adhesive substance, and the adhesive side (14) of the first plate (9, 21) is pressed against the jig surface that contains the glass fibers (3, 24) in accordance with the above, so that these fibers fasten to the plates (9, 22).

Abstract: An optical amplification system directs a diffraction-limited signal beam through a series of approximately 90.degree. crossings with a number of non-diffraction-limited pump beams in a photorefractive medium. All of the beams are s-polarized, resulting in an energy transfer from the pumps to the signal beam while leaving the signal beam diffraction-limited. The photorefractive medium is preferably a series of BaTiO.sub.3 :Rh crystals that receive the pump and signal beams through orthogonal faces, with their C-axes at approximately 45.degree. to both beams. A binary tree optical distribution network is used to minimize waveguide splits in forming a large number of pump beams.

Abstract: A MQW semiconductor Mach Zehnder phase modulator is formed by two Y-junctions (12, 32), each having a single waveguide (14) optically coupled with two branch waveguides (18, 20). The branch waveguides of the two Y-juntions are optically coupled in Mach-Zehnder configuration that, under zero bias conditions, has one interferometric arm longer than the other to provide a .pi. phase shift. The additional length is preferably accommodated in the branches of the Y-junctions. The phase shift, in combination with voltage dependent absorption properties and non-linear phase variations of the MQW guided regions in the Mach-Zehnder modulator results in a negative chirp and high extinction ratio for an equal, push-pull device configuration.

Abstract: A method of bonding glass-based optical elements comprising the steps of positioning a first glass-based optical element relative to a second glass-based optical element, applying a glass-based bonding compound about the first and second optical elements, and applying sufficient localized heat to the glass-based bonding compound to cause the glass-based bonding compound to soften and fuse with the optical elements.

Abstract: A light branching and coupling device excellent both in transmitting performance and in distributing performance in which the intermediate portion of an optical fiber 10a (10b) is thermally drawn to form light transmission fiber portions 11a and 15a (11b and 15b) and a light branching and coupling fiber portion 13a (13b) having a diameter smaller than that of the light transmission fiber portions and, at the same time, form tapering fiber portions 12a and 14a (12b and 14b) between the light transmission fiber portions and the light branching and coupling fiber portion so that the tapering fiber portions are tapered off gradually toward the light branching and coupling fiber portion 13a (13b) side. The light branching and coupling fiber portions 13a and 13b thus formed are fused with each other.

Abstract: The invention provides an optical waveguide structure suitable for use, for example, with a wavelength division multiplex transmission system for optical communication, which can be produced by a simple process and realizes a wavelength separation action of a high performance with a reduced propagation loss of light without provision of a gap between waveguides. The optical waveguide structure includes a first optical waveguide, a second optical waveguide including a pair of optical waveguides, and an intermediate optical waveguide for connecting the first optical waveguide and the second optical waveguide to each other. The intermediate optical waveguide is capable of propagating light of a high order mode therein.

Abstract: A confocal microscope including a light source; an optical fiber bundle defining a plurality of optical channels for receiving light from the light source and for transmitting the light to an object and for allowing light to return from the object through the optical fiber bundle; a switch for selectively switching selected fibers in the optical fiber bundle so as to allow light to selectively be transmitted and returned through individual optical channels until an image of the object is produced; and a detector for receiving returned light from the optical fiber bundle to enable the image of the object to be produced.

Abstract: A method for producing a cascaded optical space switch and a cascaded optical space switch manufactured with this method are shown being made of many optical branches produced on a single substrate. Here a method is used for growing active, i.e., controllable light amplifying or light absorbing waveguide areas, which can produce locally restrictable different layer thicknesses and/or material compositions of the grown active layers, during the same operation. The number and location of active (1, 3) and passive (2, 4) waveguide areas can be determined by the configuration of areas (M), e.g., masked with SiO.sub.2, prior to the actual growth.

Abstract: A method and apparatus for aligning optical fibers to light input and output ports or ends of a semiconductor waveguide device includes forming an LED diode in the associated substrate proximate each associated port. Each LED is positioned emitting light from the primary output mode position of its associated port. During alignment of an optical fiber to a given port, one end of the fiber is adjustably positioned adjacent the light output/input area at the given port in close contact thereto, and the other end of the optical fiber is connected to an input of an optical power meter the associated LED is energized, and the one end of the optical fiber is adjusted in position to maximize the light output intensity or power detected by the meter.

Abstract: A fiberoptic coupler capable of many functions is presented. The basic fiberoptic coupler has a first sleeve, a second sleeve, a first collimating GRIN or conventional lens, and a second collimating GRIN or conventional lens. The first sleeve holds end sections of two or more input optical fibers along the longitudinal axis of the sleeve. The second sleeve holds an end section of at least one output optical fiber. The end face of the second sleeve faces the first sleeve end face. The first collimating GRIN or conventional lens in front of the first sleeve end face collimates light signals from the input optical fibers and the second collimating GRIN or conventional lens in front of the second sleeve end face focusses light signals from at least one of the input optical fibers into the single output fiber, or at least one of the output optical fibers. With only one output fiber the coupler operates as a combiner.

Abstract: An optical switch array in an M.times.N configuration has a set of M input digital optical Y-branches; a set of N output digital optical Y-branch; and at least one S-bend interconnect waveguide connecting at least one input digital optical Y-branch to at least one output digital optical Y-branch, with the S-bend interconnect waveguide being adiabatically tapered for providing adiabatic modal evolution between the at least one input and output digital optical Y-branches. Each of the set of N output digital optical Y-branches has an associated branch separation point; and an output port of the at least one tapered S-bend interconnect waveguide is connected substantially adjacent to a respective branch separation point of a respective one of the set of N output digital optical Y-branch.

Abstract: An optical module (100) having a first side (103) and a second side (104), a plurality of input optical ports (144) and an output optical port (120) is formed. The input optical ports (144) are disposed on the first side (103) with the output optical port (156) being disposed on the second side (104) of the optical module (100). A plurality of bifurcated waveguides (118) are disposed in the optical module, the bifurcated waveguides (118) coalesce light from the plurality of input optical ports (144) into a single high power output at the output optical port (120).

Abstract: An integrated optical XY coupler having two converging input waveguide arms meeting in a central section and a central output waveguide arm and two diverging flanking output waveguide arms emanating from the central section. In-phase light from the input arms constructively interfers in the central section to produce a single mode output in the central output arm with the rest of the light being collected in the flanking output arms. Crosstalk between devices on a substrate is minimized by this collection of the out-of-phase light by the flanking output arms of the XY coupler.

Abstract: An optical branching device according to present invention comprises a cladding member, a first core member, a second core member, and a third core member. These core members are isolated each other, and the with of a edge face of the first core member is greater than total length of the widths of second and third core members terminals facing to the first core member and a gap between the second and third core members.

Abstract: The optical waveguide substrate is provided with a branch-type optical waveguide. This optical waveguide is composed of a stem portion provided between one end face and the other end face of the optical waveguide substrate and a plurality of branch portions extending in parallel with the stem portion. The optical waveguide substrate is also provided with a reflecting means for reflecting light transmitted through the stem portion toward the branch portions. Preferably, the optical waveguide is provided with a dividing portion which is continued to both of the stem portion and the branch portions, and a turning portion for optically coupling the branch portion with the stem portion is provided in this dividing portion so that the light transmitted through the stem portion is reflected toward the branch portions at said turning portion. In an active-type optical waveguide device, light modulating electrodes for modulating the light propagating through the branch portions are provided along each branch portion.

Abstract: An optical switch provides improved high speed digital optical switching with a compact and fabrication tolerant configuration, and includes a first waveguide portion, a plurality of intermediate waveguide portions connected to the first portion, with each intermediate portion associated with a first angle .theta..sub.1 where the first angle .theta..sub.1 is less than about 2.0.degree.; and a plurality of branch waveguide portions, with each branch waveguide portion connected to a respective intermediate waveguide portion and associated with a second angle .theta..sub.2 where the second angle .theta..sub.2 is less than .theta..sub.1 and is less than about 0.3.degree..

Abstract: An integrated optical Mach-Zehnder interferometer has two arms (11, 12) having different geometric path lengths. A first arm 11 includes arcuate segments (113, 114, 115, 116) and linear segments (111, 112) and the second arm 12 includes a mirror image arcuate segment (123, 124, 125, 126) for each arcuate segment of the first arm 11 and the total length of the straight segments (121) of the second arm 12 is less than the total length of the straight segments (111, 112) of the first arm 11. The integrated optical Mach-Zehnder interferometer is used as a demultiplexer with a 2.times.2 coupler at the output and as a multiplexer with a reversed beam path. The phase difference of both arms is directly proportional to the difference of the geometric path lengths.

Abstract: An optical device having a first substrate having a fast optical axis and a slow optical axis and a first end and a second substrate having a fast optical axis and a slow optical axis and a second end, the second end is positioned adjacent to the first end such that the fast optical axis of the first substrate is coupled to the slow optical axis of the second substrate and the slow optical axis of the first substrate is coupled to the fast optical axis of the second substrate, thereby permitting an optical signal to pass between the first and second substrates. The first substrate and the second substrate have substantially equal length to thereby substantially eliminate polarization dispersion.

Abstract: Integrated optical branching arrangement has a monomode waveguide 1 and a Y-branch waveguide 2. The waveguides conjointly define an abutting junction having a lateral offset (d). This is particularly advantageous when curved monomode waveguides are used. The offset is suitable for setting the power distribution ratio. The integrated optical branching arrangement can be applied to ion-exchanged devices in glass and to wavelength multiplexers.

Abstract: An optical branching device comprising: a substrate; a first core member formed on the substrate, having a first edge face; a second core member formed on the substrate, tapering toward the first edge face of the first core member, having a second edge face facing the first edge face at a given space; and a third core member formed on the substrate, tapering toward the first edge face of the first core member, having a third edge face facing the first edge face at a given space.

Abstract: A composite optical device has a first and second chips. The first chip has a substrate on which M pieces of optical waveguides for transmitting communication light, N pieces of optical waveguides for transmitting monitoring light and M-input/N-output star couplers are formed in an integrated form, and the second chip has a substrate on which N pieces of optical waveguides for transmitting communication light, N pieces of optical waveguides for transmitting monitoring light and N pieces of 2-input/2-output star couplers are formed in an integrated form. A first and second blocks holding optical fibers are joined respectively to the first and second chips. When the composite optical device in which the first and second blocks and the first and second chips are joined is incorporated into the optical communication system, a passive double star system is constructed. By using an MT connector instead of the first block and the first chip, a single star system can be rapidly constructed.

Abstract: An integrated optical switching device for switchably converting a fraction of a first guided mode signal into a second guided mode signal of different order is provided. Added to a passive mode converter (c) provided with a bimodal waveguide, in which the conversion can take place by a periodic coupling in coupling surfaces 1-N as a consequence of a specific geometry (f, g), are electrodes (10, 14) for switchably disrupting the coupling, as a consequence of which the conversion does or does not take place. Preferably, the optical switching device is constructed on semiconductor material and the modification is carried out by charge carrier injection. On/off and directional switches based on this are provided. As a result, the advantages of the present system are very good integrability, short length, no critical parameters in the manufacture, and operation at low control currents.

Abstract: An optical filter is adapted for selectively transmitting electromagnetic radiation within a wavelength passband bounded by a pair of stop bands of relatively low transmissivity. The filter includes at least one Bragg grating formed in a waveguiding optical medium. The Bragg grating has at least one wavelength band of relatively low transmissivity. This low-transmissivity band corresponds to at least a portion of one of the stop bands of the filter.

Abstract: A system for tuning an integrated optical switch element utilizes a reflection from a light signal that is propagated into a first input port defined on one side of an interaction region of the optical switch element. The reflection occurs beyond an opposite side of the interaction region from the side on which the light signal is introduced. The reflection is detected at a second input port of the optical switch element on the same side of the interaction region as the side on which the light signals is introduced. The reflection is used to tune the optical switch element to a desired switch state by minimizing the reflection detected at the second input port. By minimizing the reflection detected at the second input port for a desired switch state, the strength of the optical signal through the wave guide channels intended to be used to propagate the light signal in the desired switch state is maximized.

Abstract: A programmable wavelength discriminator for isolating individual wavelength carriers from an optical signal including a plurality of wavelength carriers. The discriminator preferably has a pair of waveguides, with each waveguide having imprinted therein a reflecting grating whose period is chosen to reflect the wavelength to be isolated. A receiver such as a photodetector interrogates the selected wavelength. A programmable optical switch determines through which waveguide the composite optical signal will travel. A method of isolating discrete wavelengths from an optical signal comprising a plurality of wavelengths is also discussed.

Abstract: A cladding layer covers a part of a substrate and two core layers are formed in the cladding layer. The two core layers merge with each other and a head of a common part of the two core layers appears on a side wall of the cladding layer. A guide portion is located near the side wall. A reflective body having an end face coated with a reflective film is positioned by the guide portion so that the head of a common part of the two core layers adheres to the reflective film.

Abstract: The invention comprises (a) a divider (D) by 2 of the optical power received at one input (E.sub.1, E.sub.2) and (b) two groups of single mode waveguides coplanar to the divider and symmetrical relative to the axis of symmetry (Z) of the divider (D), each group being composed of waveguide sections connected in tree and branch fashion by Y junctions (J.sub.ii) between one input junction (J.sub.11, J.sub.12) connected to one of the outputs of the divider and N sections of waveguide difining N outputs (S.sub.1 to S.sub.16) of the coupler parallel to the axis of the divider. According to the invention, each of these input junctions (J.sub.11, J.sub.12) has a rectilinear input branch (B.sub.1) with predetermined length such that the transverse distribution of the optical power at the output of the rectilinear input branch (B.sub.1) is centered to a large degree on the axis of this input branch.

Abstract: The present invention relates to a coupler having one input port and 2.sup.n output ports which includes a plurality of essentially coplanar waveguides connecting the input port to one of the 2.sup.n output ports. The plurality of waveguides are arranged in two symmetrical groups in relation to the axis of the coupler and have points of inflection. Each of the waveguides includes branches connected in a tree-like manner by n levels of Y-junctions where the waveguides connecting at least two of the output ports that are located furthest from the axis of the coupler to the input port have no singularities and between the first level and the nth level of the Y-junction have points of inflection located outside the junctions. Further, the junctions located along these waveguides have axes of symmetry which are not parallel to the axis of the coupler.

Abstract: An X-geometry optical switch includes primary and secondary input branch waveguides merging at a junction, and first and second output branch waveguides optically coupled to the input branches at the junction. In a dual electrode configuration, one electrode is positioned on the primary input branch waveguide and the other electrode on one of the input branch waveguides. By applying a common or opposite polarity bias to the electrodes, changes in the waveguide refractive optical indices are produced so that light propagating through the primary input is directed to one of the output branch waveguides in accordance with adiabatic modal evolution. In another X-geometry optical switch, the electrode on the output branch is eliminated by fabricating the output branch waveguides to exhibit a natural index asymmetry. Accordingly, since there is a normal ON-OFF path designation without biasing, only the single electrode on the primary input branch waveguide is necessary to effect switching.

Abstract: In an optical relay amplifier of the present invention, an inputted signal optical is divided into a plurality of lights by the first optical coupler. One of the divided inputted signal lights is amplified by an optical amplifier, the other inputted signal light is made to pass through a bypass optical waveguide path provided. The amplified light from the optical amplifier is coupled with the light that has passed through the bypass optical waveguide path by a second optical coupler, and the optical amplifier is a semiconductor laser amplifier including a V-shaped optical waveguide path and two end portions connected with the optical waveguide paths of the first and second optical couplers. A reflecting surface is formed in a returning end portion of the V-shaped optical waveguide path.

Abstract: A mid-span branching method for an optical path including a multi-fiber optical cable which is constituted by a multi-fiber ribbon with a plurality of optical fibers arranged in a plane and integrated with a common coating, includes the first step of exposing an intermediate portion of the multi-fiber ribbon from the multi-fiber optical cable (step 101), the second step of extracting the exposed multi-fiber ribbon (step 102), the step of separating at least one single-core optical fiber from the extracted multi-fiber ribbon (step 103), and the step of connecting the single-core optical fiber separated from the multi-fiber optical cable to a single-core optical fiber branched from a branch cable (steps 104, 105).

Abstract: An alignment-tolerant fabrication of a waveguide structure having a symmetrical component structure and an asymmetrical component structure such as an asymmetrical X junction, with the aid of the technique of double masking is presented. The entire waveguide structure is defined by two different mask patterns (p.sub.1, p.sub.2) which are applied successively and in a mutually overlapping position. The two mask patterns are aligned with respect to one another according to alignment directions parallel (z-axis) and perpendicular (x-axis) to the axis of symmetry of the symmetrical component structure. Each mask pattern comprises a first asymmetrical component pattern (32;35) and a second asymmetrical component pattern (31,33; 34,36). The first component patterns (32 and 35) each define a separate portion of the asymmetrical component structure.

Abstract: An optical waveguide device usable as an optical wave-modulator and having a reduced DC drift includes a LiNbO.sub.3 substrate, an optical waveguide formed in a front surface portion of the substrate, a dielectric layer covering the front surface of the substrate and the optical waveguide surface, and an electrode system arranged on the dielectric layer, the dielectric layer comprising a matrix component consisting of an amorphous SiO.sub.2 and a doping element component consisting of Li and/or Nb; and having a refractive index lower than that of the amorphous SiO.sub.2 matrix free from the doping element component.

Abstract: An optical waveguide circuit comprises a mode splitter and an input guide (1/4/6.1) and first and second output guides (6.2/2, 6.3/3), and a mode converter (5) incorporated in the input guide for converting a fraction of an optical signal (I.sub.i), entering via the input waveguide, of a first propagation mode into a second propagation mode having mutually different order. The mode converter (5) has a first waveguiding section (5.1) and a second waveguiding section (5.2), which adjoin each other via a single discontinuity (7). The first and second sections (5.1 and 5.2) have propagation modalities, as a result of which, at the discontinuity, a coupling can take place between two propagation modes of different order, whereas the extent (x) of discontinuity determines the fraction of conversion for obtaining a desired splitting ratio in emitting signals (I.sub.o1, I.sub.o2).

Abstract: A Mach-Zehnder optical modulator in which the chirp parameter can be varied by adjusting the optical power splitting ratio between the two arms of the interferometer. The modulating voltage is supplied to a single arm or alternatively to both arms in a push-pull configuration. For an appropriate power splitting ratio negative chirp is achieved with approximately equal push-pull modulating drive voltage. This results in optimum distance and bit rate characteristics with low drive power.

Abstract: The present invention relates to a device and a method respectively for dispersion compensation in a fibre optic transmission system in which an optic signal is fed to the device. The device comprises an optic separating device for spectral optic splitting of the optic input signal into two branches in an upper and lower modulation sideband, a delay device for selective delay of the spectral bands in relation to one another, and a combining device for combining the sidebands.

Abstract: A wavelength selective structure is coupled to an adiabatic Y-coupler via a multimode section which supports both symmetric and antisymmetric modes. One single mode branch of the coupler converts guided light to a symmetric mode, whereas the other single mode branch converts guided light to an anti-symmetric mode. The structure, which includes a pair of single mode waveguide arms coupled to the common section and a reflection device (such as a grating or ROR) located in each arm, converts reflected light from a symmetric mode to an anti-symmetric mode and conversely. Applications described include a channel dropping fiber and channel balancing apparatus for WDM systems, and a dispersion compensator for fiber optic systems.