Abstract: A manufacturing method for an optical waveguide device. The manufacturing method includes the steps of forming an optical waveguide in a substrate having an electro-optic effect, forming an SiO2 film on the substrate, forming Si films on the SiO2 film, the lower surface of the substrate, and at least a part of the side surface of the substrate to thereby make a conduction between the Si film formed on the SiO2 film and the Si film formed on the lower surface of the substrate. The manufacturing method further includes the steps of applying a photoresist to the Si film formed on the SiO2 film, patterning the photoresist so that a portion of the photoresist corresponding to the optical waveguide is left, forming a groove on the substrate along the optical waveguide by reactive ion etching, and removing the photoresist and the Si films.

Abstract: An operation unit of a PMD compensation module includes a PBS (polarization beam splitter), a compensating part and a combiner. The PBS separates an optical input into a first polarized signal and a second polarized signal. The compensating part includes a fixed prism and a movable prism. The first polarized signal outputted from the PBS travels through the fixed prism and the movable prism in series. The light path of the first polarized signal in the movable prism is elongated or shortened according to a position of the movable prism. A continuously variable delay can thus be applied between the first and second polarized signals. The combiner recombines the first polarized signal received from the compensating part and the second polarized signal received from the PBS into an optical output signal.

Abstract: Characteristics are rendered variable and high-functional by using the side-pressure inductive polarization mode coupling of a PMF to thereby change the position and magnitude of a side pressure. An input light is incident via a polarizer (2), and an outgoing light is output via the PMF (1) and another polarizer (3). Light may enter and go out in an opposite way. The PMF (1) has two polarization axes orthogonal to each other, and the polarization axis of the polarizer (2) is coupled so as to agree with one end of the polarization axis of the PMF (1). The polarization axis of the polarizer (3) is coupled so as to agree with one end of the polarization axis of the PMF (1). The PMF (1) induces polarization mode coupling when a polarization light tilted a specified angle with respect to the polarization axis is incident to apply a side pressure to the PMF (1).

Abstract: An optical transmission system includes a number of corresponding modular multiplexing and demultiplexing units used in transmitting and receiving an optical signal respectively. Additionally, compensation components compensate for optical dispersion experienced by the optical signal. The modular multiplexing and demultiplexing units are assembled in a cascade fashion at the transmit side and the receive side of the optical transmission system, respectively. The dispersion compensation components share dispersion compensation fiber across the cascaded units.

Abstract: A fiber optic cable is provided with connectors at terminal ends thereof. The connectors are configured to join TOSLINK compatible components together so that the cable can transmit an optical signal therebetween. A fiber of fused silica glass is provided with a plastic cladding material. Ball lenses are located at each terminal end of the fiber to enhance a signal intensity while maintaining signal quality passing through the cable and between the components joined together by the cable.

Abstract: The directional coupler switch is configured by a parallel waveguide including a first region which is subjected to a nonlinear action and a second region which is not subjected to a nonlinear action. A dispersion relationship of the first region is varied due to the nonlinear action to switch over an exit of light entering from an input side to cause the switch to function as an optical switch. A dispersion curve of the first region has: a region of a constant frequency in one of an even mode and an odd mode which are two kinds of eigen modes of the parallel waveguide; and a region in which gradients of the two eigen modes at frequencies belonging to a region other than the region of a constant frequency are substantially equal to each other. The gradients of the two kinds of eigen modes indicate monotone decreasing or monotone increasing.

Abstract: The index of refraction of waveguide structures can be varied by altering carrier concentration. The waveguides preferably comprise semiconductors like silicon that are substantially optically transmissive at certain wavelengths. Variation of the carrier density in these semiconductors may be effectuated by inducing an electric field within the semiconductor for example by apply a voltage to electrodes associated with the semiconductor. Variable control of the index of refraction may be used to implement a variety of functionalites including, but not limited to, tunable waveguide gratings and resonant cavities, switchable couplers, modulators, and optical switches.

Abstract: A filter device and method are presented for filtering a multi-channel randomly polarized light signal to separate therefrom at least one specific channel. The device comprises a polarizer assembly, and a filter structure. The polarizer assembly is operable for processing the multi-channel randomly polarized light signal to split it into two multi-channel light components of a predetermined polarization identical for both of said two multi-channel light components; and for processing two identically polarized light components to produce a randomly polarized light signal. The filter structure is operable to process said two multi-channel light components of said predetermined polarization to select from each of said two light components the specific channel, and thereby produce two first output light components of the specific channel propagating through spatially separated first light paths.

Abstract: We introduce a new all-optical mechanism that can compress the bandwidth of light pulses to absolute zero, and bring them to a complete stop. The mechanism can be realized in a system consisting of a waveguide side-coupled to tunable resonators, which generates a photonic band structure that represents a classical analogue of the Electromagnetically Induced Transparency. The same system can also achieve a time-reversal operation. We demonstrate the operation of such a system by finite-difference time-domain simulations of an implementation in photonic crystals.

Abstract: Provided is a wavelength tunable optical filter of a micro-electro-mechanical system (MEMS). The wavelength tunable optical filter comprises two optical fibers or optical waveguides having their optical axes aligned to each other, two lens for collimating light at leading ends of the optical fibers or optical waveguides, two or more mirrors formed on a substrate, thermal actuators supporting at least one of the mirrors, wherein one of the mirrors is actuated by thermal expansion of the actuator. Because all mirrors are formed on a substrate, a manufacturing process is simple and an initial resonance wavelength can be precisely adjusted. Since the thermal expansion is generated by the electrical current directly flowing through the thermal actuators, it can be actuated by a low consumption power. Also, since an electrostatic force is not used to move the mirrors, a sticking phenomenon between the mirrors does not occur, and the wavelength can be tunable in a wide range.

Abstract: A efficient and inexpensive optical WDM network architecture with add and drop couplers. Add couplers and drop couplers connected to a network optical fiber with wavelength blocker units which filter out optical signals at selected wavelengths on the optical fiber. The wavelength blocker units are distributed among the add and drop couplers so that each segment of the optical fiber between pairs of neighboring wavelength blocker units has at least three add and drop couplers. More specifically, each segment has the following relationship: THRU+ADD+DROP+LOCAL?TOTAL where THRU is the number of channels passing through the segment; ADD is the number of channels added within the segment; DROP the number of channels dropped within the segment; LOCAL the number of channels confined within the segment; and TOTAL is the total capacity of the optical fiber.

Abstract: A system for the transmission of signals to or between underwater installations, uses optical fibres for the transmission of optical signals to/from a control unit or between the installations. The system includes a conversion unit coupled to one of the ends of the optical fibre for conversion of the optical signals to high frequency radio signals and/or conversion of high frequency radio signals to optical signals, a conversion unit having a coupling to an electrical power supply cable for the transmission of power to the underwater installation, where the coupling unit is coupled to the conversion unit to transfer the high frequency radio signal along the power supply cable to and/or from the underwater installation, and at least one transducer unit in the underwater installation for receiving and/or emission of the high frequency radio signal.

Abstract: In order to provide a near field light head capable of guiding light efficiently to a near field light generating element, capable of being fabricated easily and at low cost and in correspondence with small-sized formation and thin-sized formation, the near field light head of the present invention has a transparent board including a near field light generating element at a lower face thereof. An upper face or the interior of the transparent board is formed with a lens to be opposed to the near field light generating element. The upper face of the transparent board is mounted with a single mode fiber. The single mode fiber is successively connected with a graded index (GI) fiber and a coreless fiber. An end face of the coreless fiber which is not connected to the GI fiber constitutes a reflecting face disposed at 45 degrees relative to the upper face of the transparent board. The reflecting face is arranged right above the lens.

Abstract: An optical filter that includes a resonator cavity comprised of a saturable absorber material is provided. An input signal waveguide, a non-resonant wavelengths output waveguide, and a resonant wavelength output waveguide are coupled to the cavity. A refractive index of the saturable absorber material is altered so that a resonant wavelength output is directed down the resonant wavelength output waveguide and non-resonant wavelengths are directed down the non-resonant wavelengths output waveguide.

Abstract: A resonant optical modulator comprises a transmission fiber-optic waveguide, a circumferential-mode optical resonator transverse-coupled thereto, a modulator optical component transverse-coupled to the circumferential-mode resonator, and a modulator control component. A control signal applied to the modulator optical component through the modulator control component alters the round-trip optical loss of the circumferential-mode resonator, thereby altering the transmission of a resonant optical signal through the transmission fiber-optic waveguide. The modulator optical element may comprise an open waveguide or a closed waveguide (i.e., resonator). The resonator round-trip optical loss may be altered by altering the optical absorption/scattering of the modulator optical component, by altering the amount of optical power transfer between the resonator and the modulator optical component, or by altering an optical resonance frequency of a resonant modulator optical component.

Abstract: The present invention relates to coupling high power optical sources into small diameter optical fibers. In a first embodiment, an optical source is provided to the side of a fiber. The fiber is a single mode fiber, which has a cladding and a core, with a Bragg grating written into the core at a low angle. Light emitted from the optical source is index-match coupled into the cladding by using an index-matched element, and subsequently coupled into the fiber core along its length. Alternatively, the light is launched into an end of a larger diameter fiber with a mode reducing means, e.g. long period grating, therein for directing the light into the small diameter fiber.

Abstract: An optical fiber (10) having a first section (10A) with little or no small-angle scattering (SAS) and a second section (10B) with an increased amount of SAS is disclosed. The optical fiber is formed by changing the draw temperature (TD) and/or the draw speed (VD) so as to induce index of refraction perturbations (P) at a core interface (40). The SAS optical fiber is useful in forming an evanescent optical fiber sensor (400), wherein the increased SAS enhances an evanescent wave portion (436) of a guided wave (434), which leads to increased sensitivity when measuring a property of a test medium (500).

Abstract: The present invention is directed to a method for enhancing functionality for photonic devices each including at least one operable surface. This method includes stacking the photonic devices such that each of the operable surfaces are aligned to form a composite surface, applying a film adapted to receive a replication to the composite surface and replicating a pattern of nanostructures in the applied film. Substantially, each of the operable surfaces is replicated with a sufficient portion of the replicated pattern of nanostructures to enhance operation of the devices by performing a given function associated with the nanostructures.

Abstract: An optical transmitter module for creating an optical signal having the same wavelength as an incoherent light inputted thereinto is provided. The module includes a substrate, a multi-layer crystal growth layer including a first area for amplifying the incoherent light and the optical signal and a second area for creating an optical signal having the same wavelength as the incoherent light amplified by means of the first area, and an electrode unit for independently injecting currents into the areas of the multi-layer crystal growth layer. A light generated at a broadband light source is spectrum-sliced and injected into the optical transmitter module so that a wavelength division multiplexing light source is realised.

Abstract: An exemplary WDM coupling device may include optical fibers. The coupling device may also include region(s) having varying coefficients of thermal expansion. During a temperature variation, one or more of the region(s) may alter in size to substantially cancel temperature-dependent changes associated with the WDM coupling device.

Abstract: A bidirectional transmitting and receiving device includes a transmitting component with an emission area of a first size, and a receiving component with a receiving area of a second size. The device further includes coupling optics for coupling light between the transmitting component and the receiving component on the one hand, and an optical waveguide to be coupled thereto on the other hand. The coupling optics have two imaging systems that are arranged one behind the other such that the light that is emitted from the transmitting component is imaged by the first imaging system on an intermediate plane on which the receiving component is located, and in the process passes through the receiving component or passes by it at the side.

Abstract: A recirculating delay line that includes an optical delay circuit generates repetitions of an input signal waveform that is of limited time duration.

Abstract: Tunable optical filters using whispering-gallery-mode (WGM) optical resonators-are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

Abstract: A limiter for limiting selected frequency components by generating Stokes waves in a stimulated Brillouin scattering medium. The generated Stokes waves create a seed that is provided to another stimulated Brillouin scattering medium. The seed selecting the undesired frequency components to be attenuated.

Abstract: An optical splitter includes a main waveguide, a tapered waveguide, and a split waveguide group having first and second split waveguides. The side portions of the tapered waveguide taper and expand from a first end portion toward second end portions. The widths of the split waveguides differ from each other. The whole width of the split waveguide group at connecting portions between the tapered waveguide and the split waveguides is smaller than the width of the tapered waveguide at the second end portions. Step portions are formed between the split waveguide group and the side portions.

Abstract: A fiber-optic gyroscope apparatus includes a light source, an optical coupler, a photodetector and an optical circuit device having at least one input, at least two outputs and a birefringent crystal substrate waveguide as a first segment of a Lyot type depolarizer between the input and the outputs. An input fiber of polarization maintaining fiber composition operating as a second segment of a Lyot type depolarizer is located between the optical coupler and the optical circuit device. A sensing coil is coupled to the outputs of the optical circuit device. The input fiber is fixed at approximately 45 degrees to the waveguide, with the input fiber and waveguide cooperating to form a Lyot type depolarizer. Other implementations of the fiber-optic gyroscope apparatus are also disclosed.

Abstract: Optical transmitter/receivers for use in a DWDM systems are provided. Transmission of data signals in a quadrature-return-to-zero (QRZ) format achieves a data transmission rate equal to eight times a base data rate, i.e., 80 Gbps over a 100 GHz channel if the base data rate is 10 Gbps, with high non-linear performance by setting the polarization state of the data bands such that non-linear effects induced by PMD are reduced. Additionally, a transmitter achieves a transmission data rate equal to 16 times the base data rate by sharpening the QRZ pulses and interleaving pulse-sharpened QRZ data signals in the time domain, further doubling the data rate. Using counterpropagation in the transmitter, carrier signals and data signals traverse the same length of fiber, reducing fringing effects in the transmitter. Related techniques enhance reception and detection of data at high data rates. A local pulse-sharpened carrier is mixed with a QRZ data signal at a detector reducing amplification noise by a factor of two.

Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octancic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains. Volume transmission gratings made with the new PDLC material can be electrically switched between nearly 100% diffraction efficiency and nearly 0% diffraction efficiency. By increasing the frequency of the switching voltage, switching voltages in the range of 50 Vrms can be achieved.

Abstract: An apparatus for compensation or emulation of polarization mode dispersion (PMD) effects occurring in an optical signal traveling over an optical fiber based link comprises controllable birefringence sections and devices for polarization conversion. Each section comprises birefringence optical members or parts thereof, and each section is followed or preceded by one of the controllable devices for polarization conversion. The birefringence sections are at least three in number, and at least one of these has a propagation delay different from that of the other sections. The apparatus comprises a detection device for PMD output and control of the controllable devices for feedback adjustment.

Abstract: An all-optical bistable device, comprising: a splitting device having first and second inputs and first and second outputs, for receiving first light beam at the first input and directing the first beam as second and third beams propagating through respective first and second outputs; first optical path between the first output and the second input and second optical path between the second output and the second input for creating combined optical path for the first and second beams at the second input; the combined optical path includes a saturable optical amplifier for enhancing and diminishing one of the second and the third beams for driving the optical amplifier into a saturation state to create one of two stable states in which one of the second and the third beams is an enhanced beam and the other beam is a diminishing beam; at least one tapping device for tapping output signal from one of the first and the second optical paths, and at least one coupling device for coupling input signal into one of the

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.

Abstract: The specification describes an optical pulse generator in a return-to-zero format in which a phase-modulated (PM) optical signal is converted to intensity-modulated (IM) optical pulses using chromatic dispersion. Compared with Mach-Zehnder-modulator-based pulse generators, this scheme is potentially more efficient (lower insertion loss). The pulse generator of the invention is suitable for very high data rates, e.g. 40 Gb/s. The structure of the pulse generator is a phase-modulated pulse source combined with a dispersive element having the required dispersion.

Abstract: An RF-lightwave transmitter performs successive conversions of an information-bearing input signal in order to generate an output signal suitable for transmission in a wireless communications system. The transmitter includes a high-efficiency FM laser connected to a FM discriminator. In operation, the laser converts an RF signal into a frequency-modulated optical signal, and the discriminator converts this signal into an amplitude-modulated optical signal. The discriminator performs its conversion using a high slope-efficiency linear transfer function which ensures that the AM optical signal varies in accordance with a desired operational performance. The transmitter also includes a photodiode which converts the AM signal output from the optical discriminator back into an RF signal for transmission. Experimental results demonstrated that a transmitter of this type is able to realize greater than 10 dB RF insertion gain at less than 0 dBm optical power, with a high spurious-free dynamic range and low noise.

Abstract: The invention relates to the coupling of light to and from an optical waveguide, such as an optical fiber. Light of a specific wavelength is deflected out from the fiber, or into the fiber, in a substantially transverse direction with respect to the propagation direction of light in the waveguide, by a deflector 16 arranged in the fiber core 10. Wavelength selectivity of the deflector 16 is provided by a Bragg grating means located in the fiber core 10. The deflected light is collimated, or converged towards a focus, by an interface 15 between a cladding 11, having one index of refraction, and an outer medium 12, having another index of refraction. The ratio between the radius of the cladding 11 and the radius of the core 10 made sufficiently small for the collimating, or converging, effect to appear.

Abstract: A plurality of channels of a wavelength division multiplexing system may be subjected to dispersion compensation in a fashion which enables tuning of the compensation for each individual wavelength channel. Moreover, the tuning may be done in a space-efficient fashion. The chirped Bragg gratings may be formed, for example, on a planar light circuit. Each grating may be heated to controllably adjust its dispersion compensation, in one embodiment of the present invention.

Abstract: An optical transceiver includes a main body that serves as the heat sink for the optical transceiver. A wafer-level package is attached to a first face of the main body. The wafer-level package contains at least one optoelectronic device such as a light-emitting device or a light detector. An alignment element is attached to the wafer-level package for aligning an optical fiber to the optoelectronic device. A fiber receptacle is attached to the main body for holding the optical fiber securely. One or more auxiliary components can be attached to a second face of the main body. An optional cover can be attached to the main body to cover and protect the auxiliary components. A flexible circuit is made of a pliable material and is attached to the main body. The flexible circuit electrically couples the auxiliary components and the wafer-level package.

Abstract: The present invention provides devices and methods for dynamic dispersion compensation. According to one embodiment of the invention, a dispersion compensating device includes a negative dispersion fiber having an input configured to receive the optical signal, the negative dispersion fiber having a length and dispersion sufficient to remove any positive chirp from each wavelength channel of the optical signal, thereby outputting a negatively chirped optical signal; an amplifying device configured to amplify the negatively chirped optical signal; and a nonlinear positive dispersion fiber configured to receive the negatively chirped optical signal. The devices of the present invention provide broadband compensation for systems having a wide range of variable residual dispersions.

Abstract: A gain flattening device for an optical fiber amplifier. In the gain flattening device, a first end portion, having first and second ends, receives an amplified optical signal from a first amplification fiber via the first end. A second end portion, having third and fourth ends, outputs the amplified optical signal to a second amplification fiber via the fourth end. A first connector is included for connecting the first end to the third end. A second connector is included for connecting the second end to the fourth end. At least one reflective grating is further included with a predetermined gain curve at a predetermined wavelength band. An optical coupling portion couples the amplified optical signal from the first connector to the second connector in at least one coupling region where the first and second connectors are closer to each other than in any other area, and outputs part of the amplified optical signal reflected from the reflective grating via the second end.

Abstract: An inner cladding exposure section 14 is formed by removing a part of an outer cladding 4 of an optical amplification medium fiber 10 which has a porous layer 3 between the inner cladding 2 and the outer cladding 4 in a longitudinal direction. An end surface 23 of an optical fiber 20 for the excited light incidence is cemented on an outer periphery of the exposed inner cladding 2. The excited light 24 is incident into the optical amplification medium fiber 10 from the optical fiber 20 for the excited light incidence. By doing this, it is possible to provide a method for exciting a light in an optical amplification medium fiber which can realize a superior amplitude while emitting the excited light so as to be incident into the optical amplification medium fiber highly efficiently.

Abstract: A higher-order dispersion compensator for tuning a polarization controlled signal having a first order polarization mode dispersion component, a second order polarization mode dispersion component, and a variable chromatic dispersion component. The compensator includes a first tuning element that adjusts the first order polarization mode dispersion component of the polarization controlled signal, and a second tuning element that adjusts the second order polarization mode dispersion component and the variable chromatic dispersion component of the polarization controlled signal. The first tuning element, which includes a differential delay line, includes a polarization beam splitter coupled to receive the polarization controlled signal. The first tuning element includes a first waveguide optically coupled to receive a first polarization component and a second waveguide optically coupled to receive a second polarization component. A first tuning mechanism is provided that tunes one of the gratings.

Abstract: A tunable optical filter has a large diameter cane waveguide with “side-holes” in the cane cross-section that reduce the force required to compress the large diameter optical waveguide without overly compromising the buckling strength thereof. The large diameter optical waveguide has a cross-section of at least about 0.3 millimeters, including at least one inner core, a Bragg grating arranged therein, a cladding surrounding the inner core, and a structural configuration for providing a reduced bulk modulus of compressibility and maintaining the anti-buckling strength of the large diameter optical waveguide. The structural configuration reduces the cross-sectional area of the large diameter optical waveguide. These side holes reduce the amount of glass that needs to be compressed, but retains the large diameter.

Abstract: A tunable dispersion compensator and a tunable dispersion compensation method having a simple structure which can be easily controlled are provided. A tunable dispersion compensator 201 is constructed of first to nth ring resonators 2021, to 202n having the same delay time spectrum arranged in series. These resonators are provided with first to nth ring-shaped waveguides 2041 to 204n for a common linear waveguide 203 through directional couplers 2061 to 206n. Heaters 2051 to 205n are disposed in the first to nth ring-shaped waveguides 2041 to 204n. By controlling temperatures of these heaters, central wavelengths of the respective ring resonators 2021 to 202n are controlled and the dispersion of an optical signal input to the waveguide 203 is compensated.

Abstract: The invention concerns monomode or multimode optical fibers provided with a lens with an end taper, obtained by selective photopolymerization of a formulation, and with improved performances through the use of novel parameters and technical processes enabling production of polymer tapers with optimized characteristic required for a wide range of applications. The monomode or multimode optical fibers can, for certain specific applications, be equipped with a metallized polymer taper except for a nanometric opening for sensing or emitting light or a polymer taper whereof the formulation contains fluorescent particles. The novel fibers are essential components in various fields such as telecommunications (high performance connectors) or instrumentation (optical radiation comparator probes for scanning optical microscopy and near-field optical microscopy).

Abstract: Forming a plurality of loops in an optical fiber around a spool adjacent to an exposed end face can suppress internal reflections from the exposed end face. The radius of the loops can attenuate light that is propagating to and from the end face by causing light to leak out of the optical fiber's core and into its cladding. The radius can be selected to control physical stress in the optical fiber and promote reliability. The radius and the number of loops can be selected to meet a return loss specification. The loops can be formed by coiling the optical fiber around a spool that includes a slot for holding the optical fiber until it is put into service.

Abstract: This invention provides a flat dispersion frequency discriminator (FDFD) capable of having a substantially flat dispersion with either a positive or negative dispersion along the spectrum region of the discriminator. This way, a FDFD may not cause substantial distortion of the intensity patter of its output to minimize the occurrence distortion due to overshooting or undershooting of the intensity pattern depending on the relative spectral alignment of the laser output relative to the filter transmission.

Abstract: There is provided an apparatus for performing, by optical code division multiplex access, at least one of encoding and decoding of wavelength-division-multiplexed light. The apparatus includes: an optical input/output section 203 for handling input/output of the wavelength-division-multiplexed light; and N fiber gratings (where N is an integer equal to or greater than two) 101 to 103, which are in a series connection to the optical input/output section 203. Each of the N fiber gratings has a sampled grating structure having an alternating array of first regions (11 to 14; 21 to 24; and 31 to 34) which provide a refractive index modulation with a relatively large amplitude and second regions (201) which provide a refractive index modulation with a relatively small amplitude, the first and second regions being disposed with a constant period P.

Abstract: A dispersion compensation system includes one or more etalons optically coupled in series. The optical path length is used to achieves the desired dispersion compensation. In one example, at least some of the etalons are tunable in OPL and have a non-tunable front reflective interface. The dispersion compensation system can be tuned, for example to compensate for different amounts of dispersion, different combinations of dispersion offset and dispersion slope and/or manufacturing variations. In another example, the etalons all have a non-tunable front reflective interface. The optical path length is selected to compensate for chromatic dispersion that varies from one wavelength channel to the next.

Abstract: A photonic switch uses a cost-effective DWDM optimized switch architecture allowing the introduction of DWDM into the metro network. In order to implement this architecture cost-effective ways of implementing the optical carrier frequency/wavelength precision required for a Dense Wavelength Division Multiplexing 100 GHz or 50 GHz on-grid solutions are needed. The photonic switch acts as an intermediary between the WDM density of the access portion of the metropolitan photonic network and the DWDM density of the core photonic network. The metro photonic switch introduces optical carriers that are all generated in the photonic layer adjacent to it and allocates them out to the photonic access nodes for modulation. This has the advantage of providing the optical carriers to be modulated from a centralized highly stable and precise source, thereby meeting the requirements for DWDM carrier precision, whilst generating these carriers in relatively close proximity to the modulators.

Abstract: An optical coupler is provided. It has a bundle of multimode fibers with a few-mode fiber in its centre. Such bundle is fused at one end which is the output end for the signal that is transmitted by the few-mode fiber. To make the coupler, this output end of the bundle is aligned and spliced with a large area core double clad fiber while preserving the modal content of the feed-through. A method for making such optical coupler is also provided. It includes the steps of bundling a central few-mode fiber with a plurality of multimode fibers and then fusing one end of such bundle and aligning it and splicing with a large core double clad fiber, while preserving fundamental mode transmission from one to the other.

Abstract: Photonic signals of high bandwidth are input into a planar spiral of waveguide. The spiral has a number of waveguide loops having a series optical tap areas wherein optical energy is leaked from the loops. The leaked optical energy is received by optical tap waveguides that carry the light for further processing.