Abstract: A Terahertz Optical Asymmetric Demultiplexer (TOAD) having preferably two non-linear elements (NLES) in which the extinction ratio is enhanced by saturating both NLEs when closing a switching window. A data signal input on one port of the TOAD is split onto two optical paths, each including one NLE. The optical paths converge at an output port. To start a switching window, a first control signal is input on an optical path that includes only one of the two NLEs. To close a switching window, one or more control signals are input such that both NLEs receive a control signal at a predetermined time after the first control signal is received by one of the NLEs. Only data signals passing through the first NLE during the switching window are output on the output port. Since both NLEs receive a second control signal at the same time, they decay together and thus avoid creation of unintended switching windows.

Abstract: An optical waveguide device has a hybrid core and a cladding. A first waveguide having a glass core is coupled to a polymer waveguide disposed adjacent and parallel to the first waveguide such that the respective cores are contiguous in a coupling region. The polymer is a thermo-optically active polymer. A heater is provided over the coupling region and the refractive index of the polymer is varied by applying heat to the region. By application of sufficient heat, the refractive index of the polymer can be changed to approach the refractive index of the cladding whereby the device acts as a simple glass waveguide. In the absence of heat, the device acts as a MMI coupler.

Abstract: An acousto-optic filter includes an optical fiber with a longitudinal axis, a core and a cladding in a surrounding relationship to the core. The optical fiber has multiple cladding modes. At least one acoustic wave generator is included and made of a sufficiently high frequency piezoelectric material to produce a longitudinal acoustic wave. An acoustic wave propagation member has proximal and distal ends. The distal end is coupled to the optical fiber and the proximal end is coupled to the acoustic wave generator. The acoustic wave propagation member propagates the longitudinal acoustic wave from the proximal to the distal ends and excites the longitudinal acoustic wave in the optical fiber.

Abstract: An optical communication assembly has an optical cross connect coupled to a first, a second, a third and a fourth set of optical fibers. A first demultiplexer is coupled to a first input fiber and the first set of optical fibers and a second demultiplexer is coupled to a second input fiber and the second set of optical fibers. A first multiplexer is coupled to a first output fiber and the third set of optical fibers. A second multiplexer is coupled to a second output fiber and the fourth set of optical fibers. A first set of attenuators is coupled to the third set of optical fibers and a second set of attenuators coupled to the fourth set of optical fibers.

Abstract: An acousto-optic filter has a non-birefringent single mode optical fiber with a longitudinal axis, a core and a cladding in a surrounding relationship to the core. The optical fiber has multiple cladding modes and a single core mode that is guided along the core. An acoustic wave propagation member has a proximal end and a distal end coupled to the optical fiber. The acoustic wave propagation member propagates an acoustic wave from the proximal to the distal end and launches a flexural wave in the optical fiber. At least one acoustic wave generator is coupled to the proximal end of the acoustic wave propagation member.

Abstract: The invention relates to an optical multiplexer/demultiplexer able to combine and/or separate at least two optical signals amongst n propagating at different wavelengths, characterised in that it comprises at least one central waveguide (4) and two lateral waveguides (5, 6), each lateral waveguide (5 and 6) constituting with the central guide (4) a pair of waveguides, each pair being disposed so as to allow a bidirectional evanescent coupling of an associated wavelength between the guides in each pair (4, 5) and (4, 6), the coupling being selective with respect to wavelength and assisted by at least one etched grating (&Lgr;), the said waveguides (4, 5, 6) being designed so that the multiplexer/demultiplexer has a functioning independent of the state of polarisation of the signals. The present invention applies to optical filters and/or direct-access networks for a bidirectional communication in the 1.3±&mgr;m window simultaneously with a video distribution at 1.5 &mgr;m.

Abstract: An optical circuit substrate having optical fiber placed and fixed in the form of a circuit on one side or on both sides of a substrate can be prepared with good efficiency by providing thereto an optical interconnection portion which makes an area for optical connection smaller and registration between an optical element and optical fiber easy.

Abstract: A method of providing a predetermined insertion loss in an optical fiber amplifier, includes the step of utilizing a predetermined, fixed, spectrally-flat loss compound (insertion loss pad, ILP) to pad total optical fiber amplifier insertion loss up to a predetermined fixed level.

Abstract: Analog noise is subtracted from an optical communication channel using stable, non-absorbing optical hard limiters. A reference signal B is combined with a control signal of intensity I2 through a 3 dB optical coupler to form a first combined signal having an intensity substantially equal to (B/2+I1). The first combined signal is processed by a first optical hard limiter to form a reflected signal having an intensity substantially equal to (I1−B/2). An information signal A is combined with a bias signal of intensity I2 through a 3 dB optical coupler to form a second combined signal. The reflected signal and the second combined signal are combined through a 3 dB optical coupler to form a third combined signal having an intensity substantially equal to 0.5(I1−B/2+A/2+I1). The third combined signal is processed by a second optical hard limiter to form a transmitted signal having an intensity substantially equal to 0.5(A−B). I2 is substantially equal to two times I1.

Abstract: An apparatus and method for photonically sampling an analog signal and encoding the photonically sampled signal. The two interferometer arms of a Mach-Zehnder interferometer section are directly coupled to the dual input ports of a directional coupler switch section. Optical pulses transmitted through the interferometer arms are phase shifted in proportion to an analog signal applied at the electrical input port of the Mach-Zehnder interferometer section. The phase-shifted pulses in each interferometer arm are coupled in the directional coupler switch section and are directed to the dual output ports of the directional switch section based upon the binary code applied to the electrical input port of the directional coupler switch section. The directional switch section has an optical length designed to provide a net phase shift of 3&pgr;/4.

Abstract: Optical signal delay apparatus and method may delay the progress of an optical signal through a semiconductor structure for a predetermined period of time. An optical delay device comprising a directional coupler and an optical signal loop may be used to delay optical signals. If desired, at least part of a directional coupler in an optical delay device may be formed from electro-optical materials so that the optical signals may be selectively transferred from the directional coupler to an optical Signal loop. Selective transfer may be provided through the application of a voltage. Optical signals with differing wavelengths may be differentiated by using a plurality of optical delay devices that each delay an optical signal having a different wavelength.

Abstract: A two-way optical communication module is provided with: a first optical wave-guide including a light emitting element 2 for emitting a light with wavelength &lgr;1, a curved wave-guide portion (optical wave-guide 6) coupled to the light emitting element 2, and a straight wave-guide portion (optical wave-guide 8) coupled to a core 11 of an optical fiber 4; a second optical wave-guide including a light receiving element 3, a curved wave-guide portion (optical wave-guide 7) coupled to the light receiving element 3, and a straight wave-guide portion (optical wave-guide 9) coupled to a clad 12 of the optical fiber 4; and a directional optical coupler 10 which includes the optical wave-guides 8 and 9 and which guides the light with wavelength &lgr;1 from the optical wave-guide 6 to the core 11 and the light with wavelength &lgr;2 from the core 11 to the optical wave-guide 7.

Abstract: An optical multiplexer/demultiplexer includes first and second directional coupling portions in which first and second optical waveguides are provided to transfer a light between the first and second optical waveguides. Lengths of the first and second optical waveguides have a difference (&Dgr;L). A product between the difference (&Dgr;L) and a refractive index (n) of the first and second optical waveguides approximates a product between a cross-propagation wavelength (&lgr;2) and a value (N′) substantially equal to an integer (N), and a product between a through-propagation wavelength (&lgr;1) and the value (N′)±0.5. Power coupling ratio differences are at least approximately 1% and at most approximately 10%. Third power coupling ratios with respect to an average wavelength of the cross-propagation wavelength (&lgr;2) and the through-propagation wavelength (&lgr;1) are at least approximately 45% and at most approximately 55%.

Abstract: The wavelength router comprises two flat waveguides, and these flat waveguides are connected by connecting waveguides. In each flat waveguide, optical path converters are created at connecting sections with the connecting waveguides. The optical path converters convert the light propagation direction in the flat waveguide to the light propagation direction in the connecting waveguides, or perform inverted conversion of this conversion. By this configuration, a compact element with a high wavelength resolution can be implemented.

Abstract: A channel waveguide optical amplifier is disclosed. The amplifier includes a substrate and an optical waveguide channel disposed on the substrate. The optical waveguide channel includes a first generally spiraling portion having a first free end and a first connected end, a second generally spiraling portion having a second free end and a second connected end, and a transition portion. The transition portion has a first transition section connected to the first connected end, a second transition section connected to the second connected end, and an inflection between the first and second transition sections. The amplifier also includes a directional coupler disposed on the substrate proximate the first free end. An amplifier assembly incorporating the channel waveguide is also disclosed.

Abstract: While an arrangement is provided in which at least one stage of a Mach-Zehnder optical interferometer optical multiplexing/demultiplexing circuit (8) is connected, at least two optical output waveguides (6) are provided at a final stage. Each of the optical multiplexing/demultiplexing circuits contains a first optical waveguide (3); a second optical waveguide (4); and a plurality of directional coupling portions (1, 2) formed in such a manner that the first optical waveguide (3) is provided in proximity to the second optical waveguide (4). Optical transmission filters (7) are provided in the respective optical output waveguides (6) of the final stage, while the optical transmission filters (7) transmit therethrough light having setting wavelengths which are determined in correspondence with the respective optical output waveguide (6).

Abstract: An apparatus comprising an optical fiber array, a spacer to receive a light beam from the optical fiber array, and a lens array having an input to receive the light beam from the spacer and an output to output the light beam is disclosed. The spacer has a first refraction index and the lens has a second refraction index.

Abstract: There is disclosed a waveguide-type wavelength multiplexing optical transmitter/receiver module which is composed of an optical demultiplexer having an optical waveguide substrate and a filter disposed on an optical waveguide substrate, a laser diode and a photodiode. On the optical waveguide substrate, a first optical waveguide and a second waveguide are formed. On a first end face of the optical waveguide substrate, there is a cross section in which these optical waveguides cross each other. On a second end face of the optical waveguide substrate, there is an optical fiber and ports for connecting the laser diode. The filter reflects light with a wavelength of &lgr;1 from the laser diode and allows light with a wavelength of &lgr;2 from the optical fiber to pass therethrough. The laser diode is so disposed that the location of a center axis is shifted in the direction of the first optical waveguide relative to a cross axis being normal to a first end face.

Abstract: An integrated circuit is presented in which optical signal propagation replaces or supplements conventional electrical signal propagation. Optical lasers, waveguides, beam splitters, and photodetectors are fabricated on top of or below conventional electrical semiconductor circuits to propagate data, clock, and control signals. Such optical signal propagation is generally more rapid than electrical signal propagation, and can free conventional electrical semiconductor circuit area by eliminating at least some conventional data busses and global clock and control wiring. Furthermore, optical clock signal propagation substantially eliminates clock skewing problems and reduces power consumption by significantly eliminating clock signal re-buffering.

Abstract: The present invention relates to a method for waveform shaping of signal light. This method includes the steps of supplying signal light to a first waveform shaper to obtain intermediate signal light, dividing the intermediate signal light into first and second signal lights, supplying the first signal light to a clock recovery circuit to obtain a clock pulse, and supplying the second signal light and the clock pulse to a second waveform shaper to obtain regenerated signal light synchronous with the clock pulse.

Abstract: Disclosed herein is a device including first and second optical couplers and a loop optical path. The first optical coupler includes first and second optical paths directionally coupled to each other. The loop optical path includes an optical fiber as a nonlinear optical medium, and connects the first and second optical paths. The second optical coupler includes a third optical path directionally coupled to the loop optical path. The optical fiber has an enough large nonlinear coefficient. The wording of “enough large” means that the nonlinear coefficient is large enough to reduce the length of the optical fiber to such an extent that the optical fiber has a polarization maintaining ability. By using such an optical fiber having an enough large nonlinear coefficient, a relatively short optical fiber can be used as the nonlinear optical medium.

Abstract: An add-drop filter, utilizing chiral couplers, that enables a new signal to be added at a particular vacuum wavelength &lgr;′k to a fiber optic line carrying n signal channels over a band of wavelengths encompassing &lgr;1 . . . &lgr;k−1, &lgr;k, &lgr;k+1 . . . &lgr;n, while an existing signal, &lgr;k, is simultaneously dropped from the signal group.

Abstract: A device for switching an optical beam in an optical switch. In one embodiment, the disclosed optical switch includes an optical switching device disposed in a well region in a semiconductor substrate layer. In one embodiment, the well region has a higher doping concentration than the semiconductor substrate layer in which the well region is disposed. The optical switching device is optically coupled to an optical input port and an optical output port of the integrated circuit die.

Abstract: In order to reduce the degree to which transmission loss occurs at the branching portion in a Y-branch structure provided at an optical integrated circuit device, the Y-branch structure through which a light signal input through an input waveguide is branched and transmitted into two output waveguides adopts the following features. The Y-branch structure is provided with a tapered waveguide having an input surface with a waveguide width a equal to the width of the input waveguide which is connected flush to the input waveguide and an output surface having a waveguide width W (>2a+g) is larger than a width 2a+g achieved by adding a width g of the gap between the output waveguides to a width 2a equal to the total of the widths of the two output waveguides each having a waveguide width a equal to the width of the input waveguide, which is connected with the two output waveguides via a stage.

Abstract: An optical directional coupler includes a first waveguide, a second waveguide and a plurality of bridge waveguides connecting the first waveguide and the second waveguide.

Abstract: An optical signal processing apparatus includes a first optical waveguide and a first slab waveguide configured to equally distribute an output light of the first optical waveguide. A first arrayed waveguide includes an aggregate of optical waveguides changing in optical length by a constant interval for dividing the output light. A second slab waveguide focuses the optical output of the first arrayed waveguide. A spatial filter receives incident light focused by the second slab waveguide and distributes the incident light on a straight line. The spatial filter also modulates the light into a desired amplitude according to the position on the straight line. The apparatus also includes a second arrayed waveguide and an aggregate of optical waveguides changing in optical length by a constant interval for applying light modulated by the spatial filter to the second arrayed waveguide. Structure is provided for converging the output light of said second arrayed waveguide to a single point.

Abstract: An apparatus for processing optical signals includes a cladding material having therein at least two elongate core regions which serve as respective waveguides. A coupling portion therein includes adjacent and parallel portions of the two waveguides which extend sufficiently closely for a sufficient distance to permit coupling of radiation between these waveguide portions. Structure is provided that respectively permits and frustrates such coupling for respective component signals having respective different wavelengths. The coupling portion may optionally include an externally controlled switching section that can have a selected one of two states in which is respectively transmissive and nontransmissive to radiation.

Abstract: A dense wavelength division multiplexing (DWDM) filter includes an optical fiber coupling device, having at least one multiple core optical fiber fusion coupled to a second optical fiber, and a dual core fiber grating. According to an especially preferred embodiment of the invention, two multiple core fibers are used with each multiple core fiber having a first core with a first effective index of refraction and a first propagation constant and a second core with a second effective index of refraction and a second propagation constant. Such an arrangement ensures a close match in effective index and propagation constant between the respective second cores.

Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterised in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being returned from the first wavelength (&lgr;1) to the second wavelength (&lgr;2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430).

Abstract: An optical fiber coupler according to the present invention comprises two optical fibers which each include a core portion serving to propagate light and a clad portion surrounding said core portion, the two optical fibers extending substantially in parallel in a same flat plane, and a melting portion in which the clad portions of the two optical fibers are fused together substantially in a line contact. Two optical fibers are arranged in parallel to permit at least parts of the clad portions to be brought into contact with each other. In this state, the two optical fibers are heated and fused mutually substantially in a line contact and are further drawn for fabrication thereof. The optical fibers are heated preferably employing an electric ceramic microheater. The two optical fibers may be same or different in structural parameters.

Abstract: An electromagnetic field frequency filter which includes a bus waveguide that carries a signal having a plurality of frequencies, including a desired frequency, and a drop waveguide. A resonator-system is coupled to the bus and drop waveguides via directional couplers and transfers the desired frequency from the bus waveguide to the drop waveguide while allowing transmission of the remaining frequencies in the bus waveguide. The input signal in the bus waveguide is coupled from the bus waveguide to the resonator-system by a first directional coupler. The resonator-system includes two sub-elements each comprising at least one resonator. The first directional coupler splits the input signal into two preferably equal parts and directs each part into a resonator sub-element. The desired frequency is transferred to the drop waveguide by a second directional coupler. The non-desired frequencies are returned to the bus waveguide, in the forward direction, by the first directional coupler.

Abstract: The purely bound electromagnetic modes of propagation supported by symmetric waveguide structures comprised of a thin lossy metal film of finite width embedded in an infinite homogeneous dielectric have been characterized at optical wavelengths. The modes supported are divided into four families depending on the symmetry of their fields. In addition to the four fundamental modes that exist, numerous higher order ones are supported as well. A nomenclature suitable for identifying all modes is discussed. The dispersion of the modes with film thickness and width has been assessed and the effects of varying the background permittivity on the characteristics of the modes determined. The frequency dependency of one of the modes has been investigated. The higher order modes have a cut-off width, below which they are no longer propagated and some of the modes have a cut-off thickness.

Abstract: An optical waveguide is formed in an integrated optics chip that includes a substrate formed of an electrooptically active material. The optical waveguide network has an input facet where optical signals may be input to the optical waveguide network and an output facet where optical signals may be output from the optical waveguide network. A structure is located in an upper layer of the substrate to prevent surface waves that propagate in the substrate from cross coupling into the output facet.

Abstract: Apparatus for and methods of providing Bragg reflection filters in a receptor such as an optical fiber uses a wavelength tunable phase mask made of a non-linear material into which an interference pattern is written by a pair of converging laser light beams. The interference pattern is probed with a reading beam of laser light that creates diffraction orders which are read into the receptor. By changing the wavelength and amplitude of the writing beams that create the interference region in the phase mask, the characteristics of the Bragg reflection filter written into the optical fiber can be changed. Accordingly, if the optical fiber is indexed along the wavelength tunable phase mask while the characteristics of the interference region are changed, thousands of different Bragg reflection filters can be formed in a single optical fiber.

Abstract: The invention relates to an optical multiplexer/demultiplexer able to combine and/or separate at least two optical signals amongst n propagating at different wavelengths, characterised in that it comprises at least one central waveguide (4) and two lateral waveguides (5, 6), each lateral waveguide (5 and 6) constituting with the central guide (4) a pair of waveguides, each pair being disposed so as to allow a bidirectional evanescent coupling of an associated wavelength between the guides in each pair (4, 5) and (4, 6), the coupling being selective with respect to wavelength and assisted by at least one etched grating (&Lgr;), the said waveguides (4, 5, 6) being designed so that the multiplexer/demultiplexer has a functioning independent of the state of polarisation of the signals. The present invention applies to optical filters and/or direct-access networks for a bidirectional communication in the 1.3 ± &mgr;m window simultaneously with a video distribution at 1.5 &mgr;m.

Abstract: A variety of wavelength division multiplexing/demultiplexing devices are disclosed. In one embodiment, an improved wavelength division multiplexing for receiving a plurality of diverging monochromatic optical beams, for combining the plurality of diverging monochromatic optical beams into a converging multiplexed, polychromatic optical beam, and for transmitting the converging, multiplexed, polychromatic optical beam. The concave diffraction grating can be formed in a variety of ways such as, for example, in a polymer material with a reflective surface. Alternatively, the concave diffraction grating may be etched into a rigid material with a reflective surface.

Abstract: Apparatuses, methods, and systems are disclosed that provide for simultaneously upconverting electrical signals carrying information at electric frequencies onto optical subcarrier lightwave frequencies that are greater and less than the carrier frequency of the lightwave onto which the electrical frequencies were upconverted. The upconversion of the electrical signals can be performed with or without suppression of the optical carrier frequency.

Abstract: Disclosed is a Brillouin erbium-fiber laser system producing multiwavelengths with a dual spacing of 10 GHz and 20 GHz. The Brillouin erbium-fiber laser system includes: a Sagnac reflector generating even- and odd-order Strokes waves by launching input lights, a first unit forming a first resonator with the Sagnac reflector, wherein the first unit is coupled to a first directional coupler in the Sagnac reflector, a second unit forming a second resonator with the Sagnac reflector, wherein the second unit is coupled to the first directional coupler in the Sagnac reflector, and a third unit for inputting Brillouin pump light into one of first and the second units, whereby the optical fiber laser system outputs multiwavelengths with a dual spacing.

Abstract: An acousto-optical filter having a wide tuning range and a method of making the same. An acoustic transducer is provided for generating an acoustic pressure wave of a selected frequency that is propagated longitudinally along an optical fiber member. The pressure wave generates a plurality of alternating localized compressions and rarefactions in the optical fiber such that a grating (i.e., periodic changes in the fiber's refractive index) is created therein. The grating reflects optical signals of a particular wavelength depending upon its period or pitch (i.e., Bragg resonance wavelength). The acoustic pressure wave's frequency is modulated by controlling the acoustic transducer such that a variable grating pitch is obtained, thereby causing a corresponding change in the Bragg resonance wavelength of the grating. In response, a reflected optical signal selected from incoming multiplexed optical signals tunes to a different wavelength.

Abstract: An optical communication module comprises an optical communication substrate provided with planar divided waveguides which are optically coupled with a light-receiving device for an optical communication, a light-emitting device for the optical communication, and another light-receiving device for monitoring a outputted light-power, wherein the planar divided waveguides have such a configuration that X-shaped branch waveguides are divided by a blind slit at a crossing thereof so that the crossing is removed, and an optical filter inserted into the blind slit. In the aforementioned optical communication module, the light-receiving device for monitoring the outputted light power can be allocated remote from as well as near the light-emitting device for the optical communication, hence a degree of freedom in mounting parts can be heightened.

Abstract: In accordance with the present invention, optical channels to be demultiplexed are supplied to first and second optical fibers via an optical splitter. Low loss interference filters, for example, coupled to the first and second optical fibers, select respective groups of channels. Each group of channels is next demultiplexed with sub-demultiplexers into individual channels, each of which is then sensed with a corresponding photodetector. Although the optical splitter introduces an optical power loss at the input to the demultiplexer, the interference filters and sub-demultiplexers create little additional loss. As a result, the total power loss associated with the present invention is significantly less than that obtained with a conventional n channel demultiplexer based on a 1×n splitter. Accordingly, large numbers of channels, e.g., in excess of forty can be readily demultiplexed and detected.

Abstract: A semiconductor optical amplifier module comprises: a demultiplexer made of a semiconductor material to separate an optical input signal containing a plurality of wavelength components into a plurality of demultiplexed signals, each of the demultiplexed signals having a different one of the wavelength component; a plurality of semiconductor optical amplifiers each optically coupled to the demultiplexer to amplify a corresponding one of the demultiplexed signals; and a multiplexer made of the semiconductor material and optically coupled to the plurality of semiconductor optical amplifiers to combine the demultiplexed signals amplified by the semiconductor optical amplifiers to produce a multiplexed signal. The demultiplexer, the semiconductor amplifiers and the multiplexer are integrated on a single semiconductor substrate.

Abstract: A temperature compensating member which comprises a polycrystalline body containing, as a main crystal, one of &bgr;-quartz solid solution and &bgr;-eucryptite solid solution, and it has a value less than 3.52 Å as an interplanar spacing of the crystal planes giving a main peak in X-ray diffraction measurement, and has a negative coefficient of thermal expansion.

Abstract: An apparatus for use in contoured architectural milieus includes a contoured large screen display having a mounting means to which modular flat display tiles including, tiles of diverse or non-standard shapes and sizes are attached, each display tile having a plurality of optical fibers affixed behind the tile and communicating with a front surface of the tile.

Abstract: An optical multiplexer/demultiplexer 1 having a plurality of first waveguides 3, a first slab waveguide 4, an arrayed waveguide grating 5 having a plurality of waveguides, a second slab waveguide 6 and a plurality of second waveguides 7, the individual waveguides being connected in the above order. The ratio of a distance between the plurality of first waveguides 3 at a connecting portion with the first slab waveguide 4 to a distance between the plurality of second waveguides 7 at a connecting portion with the second slab waveguide 6 differs from a ratio of a focal length of the first slab waveguide 4 to a focal length of the second slab waveguide 6.

Abstract: The invention pertains to a thermo-optical switch comprising a cascade of 1×M optical switches, gates for selectively blocking and unblocking the output paths of the cascaded switch, and means for driving the 1×M switches and the gates, which means are arranged to switch a data signal from an input path of the cascaded switch to one of the output paths, wherein the said means are also arranged to switch an unwanted signal, by means of a number of the remaining 1×M switches, to at least one of the remaining output paths. In the cascaded switch according to the invention, the generated heat is distributed evenly over the area of the switch and the overall amount of heat generated is reduced.

Abstract: Optical Mach-Zehnder interferometers and related devices, systems that have at least one fiber integrated or engaged to a substrate fabricated with one or more grooves.

Abstract: An optical filter apparatus and a method of designing an optical filter having a target loss wavelength characteristic. The optical filter is formed by combining a plurality of optical parts, each having a periodic loss wavelength characteristic with respect to the wavelength. The loss wavelength characteristic may be determined using a theoretical equation that includes phase and amplitude determining parameters. Nonlinear fitting is used to determine first optimum solutions for respective phase determining parameters from predetermined numerical values. Additionally, groups of numerical values are determined from numerical ranges in the vicinities of the first optimum solutions and nonlinear fitting analysis. Consequently, optimum solutions are successively calculated and respective parameters are determined to reach final optimum solutions. Finally, the determined parameters are used to approximate the loss wavelength characteristic of the optical filter.

Abstract: The present invention concerns a multi-wavelength selective switch in the form of a directional coupler structure. The directional coupler structure comprises two waveguides, wherein the waveguides arranged exhibit different effective diffractive index. The waveguides in one section are arranged in the proximity of each other, such that an optical field in the first waveguide can overlap a second waveguide and vice versa and that in said section at least two gratings are arranged for co-directional coupling. Said gratings are arranged isolated from each other. The invention further comprises a method for switching of wavelength channels through the use of said multi-wavelength selective switch.

Abstract: Disclosed is a fiber optic coupler which includes a fused, stretched, and twisted biconical tapered region; a first pair of fiber pigtail ends extending from a first end of said biconical tapered region; a second pair of fiber pigtail ends extending from a second end of said biconical tapered region; and polarization dependent loss preclusion means disposed within said biconical tapered region. Further disclosed is a method for forming the polarization insensitive coupler as described.