Abstract: A reconfigurable optical device for wavelength-division multiplexing networks, comprising two waveguides (A, B) parallel to each other, with two-dimensional confinement, coupled by a bi-directional coupler (C), suitable to selectively drop one and only one of the channels composing the Wavelength-Division multiplexing signal (WDM); the device is reconfigurable as, by appropriately varying the wavelength of the combined pumping beam inside a first waveguide (A), any channel forming the WDM signal can be dropped.

Abstract: Included among the many structures described herein are photonic bandgap fibers designed to provide a desired dispersion spectrum. Additionally, designs for achieving wide transmission bands and lower transmission loss are also discussed. For example, in some fiber designs, smaller dimensions of high index material in the cladding and large core size provide small flat dispersion over a wide spectral range. In other examples, the thickness of the high index ring-shaped region closest to the core has sufficiently large dimensions to provide negative dispersion or zero dispersion at a desired wavelength. Additionally, low index cladding features distributed along concentric rings or circles may be used for achieving wide bandgaps.

Abstract: A wavelength converter that is used in an optical communication system utilizing wavelength multiplexing. The wavelength converter has a quasi-phase matched quartz crystal that has a second-order nonlinear effect, and a light coupling device that mixes the signal light and control light and inputs this mixed light into the quasi-phase matched quartz crystal. The wavelength converter also has quartz type optical fibers between the light coupling device and the quasi-phase matched quartz crystal. The mode diameter of the quartz type optical fibers is substantially the same as the mode diameter of the optical waveguide.

Abstract: The present invention relates to a wavelength converter of structure enabling generation of converted light with high power even with a large difference between the wavelength of pumping light and the zero-dispersion wavelength. The wavelength converter includes an optical fiber having a dispersion slope whose absolute value at the wavelength of 1550 nm is 0.01 ps/nm2/km or less, for example.

Abstract: An all optical chopping device for shaping and reshaping comprising an all optical AND logic gate having a first input for receiving a first optical signal, a second input for receiving a second optical signal and at least one output. The AND gate may be arranged to produce at least at one output thereof an optical output signal corresponding to a portion of the AND product of the first optical signal and the second optical signals. The optical output signal may be narrower than at least one of the first optical signal and the second optical signal.

Abstract: Systems and methods for manipulating light with high index contrast waveguides clad with substances having that exhibit large nonlinear electro-optic constants ?2 and ?3. Waveguides fabricated on SOI wafers and clad with electro-optic polymers are described. Embodiments of waveguides having slots, electrical contacts, and input waveguide couplers are discussed. Waveguides having closed loop structures (such as rings and ovals) as well as linear or serpentine waveguides, are described. Optical signal processing methods, such as optical rectification and optical modulation, are disclosed.

Abstract: Provided is an optical transmission line in which the suppression of SBS and the achievement of other transmission characteristics can compatibly be attained. The optical transmission line is formed by connecting a first optical fiber and a second optical fiber, or by connecting a group of first optical fibers and a group of second optical fibers, in which the difference in Brillouin frequency shift therebetween is 200 MHz or more. In at least one of the first optical fiber and the second optical fiber, the transmission loss may be 0.32 dB/km or less at a wavelength of 1383 nm. In each of the first and second optical fibers, the mode field diameter may be not less than 8.2 ?m and not more than 9.8 ?m, the cable cutoff wavelength may be equal to or less than 1260 nm, and the zero dispersion wavelength may be not less than 1300 nm and not more than 1324 nm.

Abstract: In general, in one aspect, the disclosure features a fiber waveguide having a waveguide axis, including a core extending along the waveguide axis and a confinement region extending along the waveguide axis surrounding the core. The confinement region includes a periodic structure along a radial direction extending from the waveguide axis and each period in the periodic structure includes a layer of a chalcogenide glass and a layer of a polymer.

Abstract: A gap-soliton structure is provided. The gap-soliton structure includes a cladding structure having alternating layers of different index values. A core region is interposed between the alternating layers of index values. The core or the cladding structure includes one or more nonlinear materials so as to achieve gap-soliton bistability.

Abstract: A new class of surface plasmon waveguides is presented. The basis of these structures is the presence of surface plasmon modes, supported on the interfaces between the dielectric regions and the flat unpatterned surface of a bulk metallic substrate. The waveguides discussed here are promising to have significant applications in the field of nanophotonics by being able to simultaneously shrink length, time and energy scales, allowing for easy coupling over their entire bandwidth of operation, and exhibiting minimal absorption losses limited only by the intrinsic loss of the metallic substrate. These principles can be used for many frequency regimes (from GHz and lower, all the way to optical).

Abstract: Disclosed is a waveguide type optical device utilizing a nonlinear refractive index change according to a large 3rd order nonlinear optical phenomenon. The waveguide type optical device includes a signal beam waveguide through which a signal beam propagates; and a pump beam waveguide through which a pump beam propagates, wherein the pump beam waveguide is disposed adjacent to the signal beam waveguide so that the pump beam can be coupled to the signal beam waveguide, the signal beam waveguide is made of nonlinear optical materials with large 3rd order nonlinear optical property and the pump beam waveguide is made of linear optical materials, and the wavelength range of the signal beam is different from that of the pump beam. By such a structure, the pump beam is coupled to one arm of the signal beam waveguide, thereby generating a 3rd nonlinear phenomenon on one arm of the waveguide through which the signal beam passes.

Abstract: Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by performing at least one post-processing treatment on the HNLF. Particularly, UV exposure of the HNLF will modify its dispersion and effective area characteristics so as to increase its supercontinuum bandwidth, without resorting to techniques such as tapering or introducing unwanted reflections into the HNLF. The UV exposure can be uniform, slowly varying or aperiodic along the length of the HNLF, where the radiation will modify the nonlinear properties of the HNLF. Various other methods of altering these properties may be used. The output from the HNLF can be monitored and used to control the post-processing operation in order to achieve a set of desired features in the enhanced supercontinuum spectrum.

Abstract: A method is provided for forming a waveguide region within a periodically domain reversed ferroelectric crystal wherein the waveguide region has a refractive index profile that is vertically and horizontally symmetric. The symmetric profile produces effective overlapping between quasi-phasematched waves, a corresponding high rate of energy transfer between the waves and a symmetric cross-section of the radiated wave. The symmetric refractive index profile is produced by a method that combines the use of a diluted proton exchange medium at a high temperature which produces a region of high index relatively deeply beneath the crystal surface, followed by a reversed proton exchange which restores the original crystal index of refraction immediately beneath the crystal surface.

Abstract: Devices and methods for optical processing and storage are described. In a preferred embodiment, an integrated optical gate matrix, that includes a set of nonlinear elements and waveguides interconnecting at least some nonlinear elements in the set of nonlinear elements, may be configured to enable optical processing. A first subset of the set of nonlinear elements is preferably configured to function as a set of ON/OFF switches in the “OFF” state to enable a second subset of the set of nonlinear elements to be configured in at least one optical processing configuration. Configuration of the second subset of the set of nonlinear elements may be used for various optical processing operations, such as all-optical 2R or 3R regeneration, wavelength conversion, data format conversion, demultiplexing, clock recovery, logic operations and dispersion compensation. Related apparatus and methods are also described.

Abstract: The present invention provides an optical fiber of a high nonlinear characteristic which has low dispersion values in a wide wavelength region in the vicinity of a wavelength of 1550 nm. An excellent optical signal processing apparatus is realized by using this optical fiber, such as an optical wavelength converter and a pulse compressor. The optical fiber has characteristics; a dispersion slope at the wavelength of 1550 nm of ?0.01 to 0.01 ps/nm2/km, an absolute value of dispersion at the wavelength of 1550 nm of 10 ps/nm/km or less, and a nonlinear constant at the wavelength of 1550 nm of 30×10?10/W or more. A polarization retaining maintaining members are uniquely applied.

Abstract: Disclose is a photonic crystal structure comprises atomic dielectric pillars having a refractive index distribution and a structure which are both mirror-symmetrical in a thicknesswise direction of the photonic crystal. The atomic pillars are arrayed in a two-dimensional lattice pattern to form a dielectric pillar lattice. The dielectric pillar lattice is disposed within a surrounding dielectric having a uniform or substantially uniform refractive index distribution. An organic resin which serves as part of surrounding dielectric is disposed in an asymmetrical position in a thicknesswise direction of the photonic crystal.

Abstract: The present invention provides a light-enhancing component and a fabrication method thereof by using the focused-ion-beam. In the present invention, the surface plasmon polariton structure is coated on the surface of the optical fiber so as to form the light-enhancing component. When the light passes through the optical fiber, the luminous flux transmitted through the aperture on the surface plasmon polariton is enhanced, and the light beam smaller than the diffraction limitation can be transmitted to the far-field, i.e. the nano-optic sword is formed. The light-enhancing component of the present invention can be used for the optical data storage, the optical microscopy, the biomedical detections and the lithography to perform the extra optical resolutions beyond the diffraction limitation.

Abstract: Exemplary embodiments of some aspects of the invention provide an optical decoding device including: a splitting device having first, second, and third, terminals; a nonlinear element; and an attenuator, wherein the second and third terminals are associated with an optical loop including the attenuator and the nonlinear element, the nonlinear element being displaced from a mid-point of the optical loop, and wherein the decoding device is able to receive multiple encoded signals via the first terminal, to decode at least one of the encoded signals and to provide a decoded signal at the first terminal in response to the at least one encoded signal. Exemplary embodiments of further aspects of the invention provide an optical code responsive device for decoding optical encoded signals, codes, and/or symbols, for header processing, for header reading, for address decoding and/or for optical packet routing.

Abstract: A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.

Abstract: Holey optical fibers (e.g. photonic fibers, random-hole fibers) are fabricated with quantum dots disposed in the holes. The quantum dots can provide light amplification and sensing functions, for example. When used for sensing, the dots will experience altered optical properties (e.g. altered fluorescence or absorption wavelength) in response to certain chemicals, biological elements, radiation, high energy particles, electrical or magnetic fields, or thermal/mechanical deformations. Since the dots are disposed in the holes, the dots interact with the evanescent field of core-confined light. Quantum dots can be damaged by high heat, and so typically cannot be embedded within conventional silica optical fibers. In the present invention, dots can be carried into the holes by a solvent at room temperature. The present invention also includes solid glass fibers made of low melting point materials (e.g. phosphate glass, lead oxide glass) with embedded quantum dots.

Abstract: A dispersion compensator and method of dispersion compensation in which an input light is converted to a selected second wavelength, the converted light beam having the second wavelength is dispersion compensated in an amount dependent upon the second wavelength, and the compensated light beam having the second wavelength is converted to the first wavelength.

Abstract: The present invention relates to a cladding structure of an optical fiber laser capable of allowing efficient optical pumping at a core of the optical fiber laser using the concept of quantum chaos, and more particularly, to a cladding structure of an optical fiber laser, which enables efficient pumping in an optical fiber by constructing the cladding in a non-integrable structure for causing quantum chaos so that a pumping beam injected in the cladding can pass through a core of the optical fiber as much as possible.

Abstract: Provided are a tunable demultiplexer and a tunable laser, having an optical deflector in which a refractive index of a core layer of a deflection pattern region having a predetermined shape varies in response to an external electrical signal so that the optical deflector deflects incident light in the radial direction.

Abstract: The present invention relates to all optical choppers for shaping and reshaping. A chopper according to some embodiments of the invention may include a threshold device having an input terminal for receiving an optical input signal and an output terminal for emitting an optical output signal in response to a part of the input signal having intensity above a threshold level of the chopping device, wherein the output signal is narrower than the input signal. In other embodiments the device may include a first splitting device having at least first, second and third terminals, and at least one nonlinear element, wherein the second and third terminals form an optical loop including at least one nonlinear element displaced from the center of the optical loop, wherein the splitting device is arranged to receive an input signal for producing a first output signal that is narrower than the input signal. In further embodiments the optical loop includes at least one more attenuator.

Abstract: An optical fiber for communications systems, the fiber being designed to ensure a compensation of Kerr effects. The fiber has a profile which ensures that changes in power produce changes in distribution of power between core and cladding, such that the phase change associated with the changed spatial distribution of the power, is equal and opposite to the phase change due to Kerr Effect.

Abstract: A device and method for processing a signal e.g. equalizing a signal, is disclosed. Such processing involves dividing a signal into two portions that each traverses a wavepath and then are combined. The respective wavepaths impose a non-linear frequency-versus-phase dependency on a signal portion. The frequency-versus-phase dependencies that characterize the respective wavepaths are similar in shape but inverted from each other. A processed signal has significantly improved signal-to-noise ratio.

Abstract: This invention pertains to a device for broadening optical wavelength in the 2–14 ?m region comprising a light source and a highly nonlinear chalcogenide fiber associated therewith whereby a light signal is passed from the light source into the fiber wherein and through interactions between the light signal and the material, bandwidth of the light signal is broadened in the 2–14 ?m region.

Abstract: A supercontinuum light emitting device comprises an effectively CW light source producing light of wavelength ?1 within a specified bandwidth and a nonlinear fiber optically coupled to the light source. The nonlinear fiber has a plurality of fiber segments with different zero dispersion wavelengths ?oi, where each successive fiber segment has zero dispersion wavelength ?oi which is larger than the zero dispersion wavelength of the preceding fiber and the zero dispersion wavelength of the first fiber segment is within ±20 nm of ?1.

Abstract: A magneto-optical device includes a waveguide structure that has at least one cladding region and core region. The cladding region and core region comprise semiconductor alloy materials. Either the at least one cladding region or the core region is doped with ferromagnetic materials so as to increase the magneto-optical activity of the device.

Abstract: An optical fiber has a Raman gain efficiency with a pump power at 1450 nanometers of equal to or more than 4 m/W, and a ratio of a nonlinear parameter ? at a wavelength of 1550 nanometers to the Raman gain efficiency with a pump power of 1450 nanometers is equal to or less than 3.

Abstract: A photonic crystal device according to the present invention includes: a substrate 201; a periodic structure portion 206 formed in or on the substrate 201, the periodic structure portion 206 having a plurality of holes 2050 and 2051 arranged in a periodic array; at least one optical waveguide 202 formed in or on the substrate 201, the at least one optical waveguide 202 being adjacent to the periodic structure portion 206; and at least one optical resonator 203 formed in or on the substrate 201, the at least one optical resonator 203 being formed in a position away from the optical waveguide 202, with at least one hole 2051 among the plurality of holes 2050 and 2051 of the periodic structure portion 206 being interposed between the optical resonator 203 and the optical waveguide 202.

Abstract: Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by incorporating at least one Bragg grating structure in the HNLF. The Bragg grating results in reflecting a core-guided signal into signal which also remains core-guided. The supercontinuum radiation generated by such an arrangement will exhibit a substantial peak in its energy at the grating resonance of the Bragg grating and a region of increased radiation in a narrow wavelength band on the long wavelength side of the peak. A number of such Bragg gratings may be formed so as to “tailor” the enhancements provided in the supercontinuum radiation. Various, well-known Bragg grating modifications (tuning, chirped, blazed, etc.) may also be used in the inventive structure to enhance the generated supercontinuum.

Abstract: A novel two-dimensional optical signal processing circuit which becomes possible only by the introduction of a concave, flat or convex reflecting structure; and a method of producing the same. Disposed on an optical wave-guiding circuit board (50) formed with an output wave-guiding path (13) and an input wave-guiding path (14) are the optical axes of the input coupling end (I) and output coupling end (U) of a coupling circuit (15) such that the optical axes pass through the same point (Q) on a reflection structure (16), the reflection structure (16) being fabricated by using a laser ablation device (30).

Abstract: A method and system for self-synchronizing an optical packet network by selecting a seed pulse from among the data pulses within a packet having no synchronization marker, transforming the seed pulse to be optically distinguishable from the remaining data pulses after the packet has been transmitted, and extracting that seed pulse for use in synchronizing the operation of the network. In one embodiment, the process is practiced using a intensity modifier (such as a fast-saturation, slow-recovery amplifier) to modify the seed pulse intensity, and an intensity discriminator (such as an unbalanced NOLM, or a dispersion-shifted fiber and bandpass filter) to extract the differentiated seed pulse.

Abstract: An optical fiber cable including a plurality of optical fibers, each optical fiber having a characteristic value in a middle field which is larger than characteristic values in fields other than the middle field of the optical fiber. The characteristic value in a respective field is a nonlinear refractive index of the optical fiber in the field divided by an effective cross section of the optical fiber in the field. The middle field and the characteristic value in the middle field are set as a combination to suppress a nonlinear phase shift generated in light transmitted through the plurality of optical fibers.

Abstract: An apparatus includes an optical waveguide and an optical filter positioned to receive light from the optical waveguide. The optical waveguide includes a sequence of alternating first and second stripes. The sequence runs along a propagation direction in the optical waveguide. The first and second stripes are formed of different polarization states of a group III-nitride semiconductor. The optical filter removes light of a preselected frequency.

Abstract: An optical fiber includes a first core with a first refractive index located in a central portion of the optical fiber; a second core with a second refractive index located in an outer periphery of the first core; a third core with a third refractive index located in an outer periphery of the second core; and a cladding with a fourth refractive index located in an outer periphery of the third core, where among the refractive indices, the first one>the third one>the fourth one>the second one. The absolute value of dispersion at the wavelength of 1550 nm is not more than 20 ps/nm/km. The effective area at the wavelength is not more than 15 ?m2. The nonlinear constant n2/Aeff at the wavelength of 1550 nm is equal to or more than 25×10?10/W.

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: The present invention provides devices and methods for 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 a systems having a wide range of variable residual dispersions.

Abstract: The present invention describes nanophotonic materials and devices for both classical and quantum optical signal processing, transmission, amplification, and generation of light, which are based on a set of quantum systems having a discrete energy levels, such as atoms, molecules, or quantum dots, embedded in a frequency bandgap medium, such as artificial photonic crystals (photonic bandgap materials) or natural frequency dispersive media, such as ionic crystals, molecular crystals, or semiconductors, exhibiting a frequency (photonic) bandgap for propagating electromagnetic modes coupled to optical transitions in the quantum systems. If the frequency of one of optical transitions, called the working transition, lies inside the frequency bandgap of the medium, then spontaneous decay of the working transition into propagating photon modes is completely suppressed.

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: An optical apparatus and method are provided for controlling the polarization of light. An incoming beam is directed at a photonic crystal. The photonic crystal is designed to act as a transmission quarter-waveplate or half-waveplate; as a reflection waveplate; or as a polarizer. In addition, the photonic crystal may be designed to accomplish phase matching in nonlinear optical mixing processes, as well as obtaining other selected effects upon incoming beams having known polarizations.

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: The present invention relates to a method of determining a quasi-phase matching efficiency in a periodically poled structure of an optical waveguide, a periodically poled structure of an optical waveguide, and an optical waveguide using the same. It is possible to effectively perform a quasi-phase matching when a width of periodic electrodes is shorter than a coherence length generally used as ½ of a quasi-phase matching period.

Abstract: According to at least one embodiment, a system comprises a Sagnac interferometric loop and a semiconductor optical amplifier (SOA) located at an asymmetric position on that loop, wherein the Sagnac interferometric loop and the SOA are operable to perform signal conversion on an input signal.

Abstract: A method and a system to produce, either in numerical simulations or in experiments, specified amounts of first, second and higher order PMD in a controlled manner, in particular large amounts. Parameters can be adjusted to obtain specific ranges of first, second and higher order PMD, and importance sampling can be used to determine the probability that the resulting PMD events can be obtained in realistic situations. Individual results obtained using specific parameter values can be combined to produce even larger ranges of PMD.

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 dispersion compensation device for compensating chromatic dispersion of optical pulses launched from the exterior is disclosed. The device comprises a waveguide and a photonic crystal part, the waveguide comprising a core part for guiding the optical pulse from an input end to an output end and a clad part consisting of a first clad layer and a second clad layer, the photonic crystal part providing a chromatic dispersion variation of a proper dispersion characteristic to the optical pulses guided through the waveguide, the chromatic dispersion variation having an absolute value of the variation and a positive or negative sign, wherein the photonic crystal part is layered onto the first clad layer, the core part is layered onto the photonic crystal part, and the second clad part is formed so that a portion of which is layered onto the photonic crystal part and a remaining part of which covers the exposed surface of the core part.

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 nonlinear phase-shift compensation method and apparatus is provided for improving system performance in optical transmission systems. The apparatus includes a phase-shift compensating device that provides a partial compensating phase shift to reduce the nonlinear phase noise resulting from self-phase modulation and amplified spontaneous emissions in an optical transmission system.