Abstract: The present invention relates to an arrayed waveguide grating having a reflective input that permits variable coupling to adjust the center wavelength. The present invention has found that by providing an arrayed waveguide grating having one or more precisely positioned input waveguides coupled through a reflective lens assembly, for providing a lateral offset to a signal propagating from the input waveguide to the planar waveguide, and for focusing a reflected input signal at a selected input point of the input planar waveguide, alignment and tuning of an input and assembly can be improved and simplified. Advantageously, variable coupling parameters can be incorporated into the reflective coupling including input position, waveguide taper and planar waveguide length increment to provide relatively simple tuning in an integrated device. Compensation for polarization effects and thermal effects can also be provided in the reflective coupling.

Abstract: An Optical Domain Signal Analyzer, having an optical filter, a dispersive element and a detector is utilized to provide high resolution spectrum analysis over a wide optical bandwidth. The optical domain signal analyzer broadly includes an optical filter for providing wavelength samples of a received optical signal, a dispersive element for receiving the samples and dispersing the samples, and a detector for receiving the dispersed signal and for providing electrical signals representative of the dispersed sample. A preferred embodiment includes a processor for receiving the electrical signal and calculating the characteristics of the spectrum.

Abstract: Plane diffraction grating 13 is formed of a material having an appropriate linear expansion coefficient and a variation in the wavelength of the reflected light from concave mirror 14 on account of thermal expansion or shrinkage of members other than plane diffraction grating 13 is cancelled out or reduced by a variation in the wavelength of the reflected light from concave mirror 14 on account of thermal expansion or shrinkage of plane diffraction grating 13. The same principle is used to deal with the effect on the wavelength of the diffracted light that may be caused by changes in the layout of individual members on account of thermal expansion or shrinkage of substrate 10a that fix them.

Abstract: A new optical sensing device containing fiber Bragg gratings, a scanning bandpass filter, an interferometer and multiple photodetectors is disclosed. The present invention also describes a new system and method for fibre Bragg grating (FBG) sensor interrogation and multiplexing. The new system combines a scanning Fabry-Perot (SFP) bandpass filter used to wavelength-multiplex multiple gratings in a single fiber, and an unbalanced Mach-Zehnder fibre interferometer made with a 3×3 coupler to detect strain-induced wavelength shifts. A passive technique for interferometer drift compensation using non-sensing FBGs is included in the system. A complete prototype system interrogates four gratings in a single fiber at a Nyquist sampling rate up to 10 kHz, with a noise floor measured near 4 n&egr; Hz−1/2 above 0.1 Hz. The inclusion of the interferometer drift compensation technique is shown to make quasi-static measurements feasible.

Abstract: Methods for connecting two optical fibers having different mode field diameters ((MFD) with low connection loss is proposed. One method comprises steps of preparing the third fiber (Fiber 3), a short length and MFD being smaller than that of the first fiber (Fiber 1) and larger than that of the second (Fiber 2), connecting the Fiber 1 to 3, connecting Fiber 2 to 3, and increasing MFD of Fiber 3 near the part connected or to be connected to Fiber 1, or MFD of Fiber 2 near the part connected or to be connected to Fiber 3 by heating the corresponding part. The other method comprises steps of preparing a short length Fiber 3 having smaller MFD than that of Fiber 1, increasing MFD of Fiber 3 near the part to be connected to Fiber 1 by heating the corresponding part, and then connecting Fiber 1 to 3, and 3 to 2 in that order.

Abstract: An optical module comprising: an optical element flip-chip mounted on a substrate; an optical waveguide formed on the substrate and optically connected to the optical element; and underfill resin filled in between the substrate and the optical element and covering an optical junction between the optical element and the optical waveguide, wherein the underfill resin is of an electrically insulating material and has a refractive index equal to or smaller than a refractive index of a clad portion of the optical waveguide. The optical element can be flip-chip mounted with improved mechanical and electrical mounting reliability and thus satisfactory optical connection can be maintained. Further, it never occurs that light passing through the optical waveguide leaks to the underfill resin in the optical junction between the optical waveguide and the optical element.

Abstract: A broadband ASE light source is provided which comprises an amplifying optical fiber doped with rare earth; a pumping light source and an output port both which are connected to one end of the amplifying optical fiber via a multiplexer; and a reflecting or circulating member which is connected to the other end of the amplifying optical fiber, whereby the amplifying optical fiber emits ASE light containing a first and second wavelength bands through the port. Particularly, a second pumping light source may be connected to the other end of the amplifying optical fiber via another multiplexer to widen the wavelength band to longer wavelength side. Further, using the amplifying Er-doped optical fiber with the pumping light sources having wavelength of a 980 nm band, the ASE light source can emit a flattened broadband of 1530 to 1610 nm, combining the two wavelength bands of 1530 to 1570 mn and 1570 to 1610 nm.

Abstract: An optical fiber cable configuration having a central strength member. The central strength member includes a hollow tube. One or more strength rods are disposed along or within the tube. To avoid water penetration, the tube is filled with a gel or water-absorbing powder, which provides a water barrier.

Abstract: A mirror angle adjustment mechanism assembled by engaging latching members of a support pivot, which have been in the state inserted through openings provided in a second hemisphere portion of a mirror holder inner, with a case pivot. A plurality of elastic plates on the support pivot are compressed against the second hemisphere portion such that the second hemisphere portion is held between the plurality of elastic plates and a first hemisphere portion provided at the case pivot. Since this mirror angle adjustment mechanism requires only three parts, the case pivot, the mirror holder inner and the support pivot, the number of parts can be reduced and ease-of-assembly can be improved.

Abstract: In an optical connector ferrule comprising an insertion opening through which one end of a coated optical fiber with the coating removed is inserted. A guide groove is provided for guiding the bare fiber of the optical fiber. A fiber hole is provided for inserting therein the bare fibers guided by the guide groove. An injection port is provided for injecting therein adhesive for securing the coated optical fiber to the ferrule. Guide surfaces are provided for guiding the bare fiber to the guide grooves at sides of the guide groove. In the similar optical connector ferrule, there is provided an enlarged portion extending forwardly from a leading edge of the injection port in a fiber inserting direction and reaching a filling space into which the adhesive is filled. Further, a ceiling surface of the enlarged portion is inclined downwardly forwardly from the injection port.

Abstract: An optical fiber assembly including a ferrule which increases the glass transition temperature of an entire epoxy system resident within the ferrule and a method for suppressing optical instabilities of an optoelectronic package are described. One or more openings are made in a ferrule body to allow reaction gases from the epoxy caused during curing to escape, allowing a greater portion of the epoxy to fully cure, thereby raising the glass transition temperature of the epoxy system.

Abstract: Optical devices and methods for attenuating, shuttering, or switching optical signals as found in telecommunications. A platform carrying a portion of a waveguide and residing in a plane of a substrate is tipped, tilted, twisted, or otherwise moved out of the plane of the substrate to divert the path of an optical signal or to change coupling between adjacent waveguides. The platform can be formed by etching a substrate while leaving one or more connection points between the platform and the substrate to hold the platform to the substrate.

Abstract: A polarization-preserving optical fiber with a high pump-radiation absorption efficiency including a core, a primary cladding surrounding the core, stress members disposed within the primary cladding, and a secondary cladding surrounding the core, primary cladding and stress members. The stress members and the primary cladding have different thermal responses, thereby inducing birefringence within the fiber. The cladding and stress members cooperate to direct light, propagating through the fiber, into the core.

Abstract: A method and system for measuring optical scattering characteristics includes coupling a continuous wave laser excitation signal to an optical fiber. Radiation backscattered by the optical fiber in response to the coupled excitation signal is detected to produce a backscattered radiation signal. The backscattered radiation signal is mixed with the excitation signal to produce a mixed signal. The mixed signal is filtered to reduce the magnitude of frequencies other than conjugate mixing frequencies relative to the conjugate mixing frequencies. The filtered signal is digitized and the magnitude of backscattered radiation from a specific portion of the fiber is calculated based on the digitized signal. The temperature of a specific portion of the fiber can be determined from the magnitude of the backscattered radiation.

Abstract: An improved method is provided for reducing four-wave mixing induced degradation in an optical data signal traversing an optical transport network that uses Raman amplifiers. The method includes: introducing at least two Raman amplifiers into the optical transport network, each Raman amplifier having a laser source, and synchronously modulating the laser sources of the Raman amplifiers, thereby reducing four-wave mixing in the optical data signal. Modulation of the laser sources is performed at such a rate that crosstalk from the modulation to the optical data signals experiencing the Raman gain is minimized.

Abstract: The invention describes an optical network architecture which uses a limited number of wavelength channels while providing flexible connections between the network nodes. Each node in the network deploys a fixed wavelength transmitter and a fixed wavelength receiver, whose wavelengths are misarranged so that a set of wavelengths of the transmitter differs from the set of wavelengths of the receiver, and wavelengths of transmitters and receivers at different nodes are arranged so that for any pair of nodes there is at least one common wavelength which is the same for one of the transmitter and receiver at one node and one of the respective receiver and transmitter at the other node, thus providing a direct connection between the nodes. The corresponding structure of the optical add/drop multiplexer/demultiplexer for use at the network node, and method of providing direct connections between the nodes, are also provided.

Abstract: A time compensation architecture for use with a plurality of optical signals is disclosed. It comprises means for receiving the plurality of optical signals, optical means for selectively delaying the propagation of each of the plurality of optical signals, and means for outputting the time delayed optical signals. The delay may be achieved by changing the indices of refraction or the material lengths of the elements and can either be an active or a passive compensation technique.

Abstract: In order to provide a small-sized and compact optical switch of 1×4 type. Two movable optical fibers are fixed on a substrate by a fixing block disposed in a middle portion of the fibers. Two movable blocks made of a soft magnetic body are mounted to the both ends of the movable optical fibers. Two soft magnetic fixing blocks are arranged on the substrate for fixing one optical fiber so as to oppose to one of the movable block, and for fixing four optical fibers so as to oppose to the movable block, respectively. Two movable blocks can be independently moved with respect to the respective fixing blocks by means of actuators. Further, it is possible to detect a position of each movable block with respect to the fixing block by means of detecting electrodes.

Abstract: A spectrometer measures a spectrum of a light beam supplied from a light source so as to obtain fine information and coarse information of the spectrum easily. This spectrometer has a holographic grating, an Echelle grating, a rotation stage and a line sensor. In the case where a single pass beam is to be detected, a control processing unit controls the rotation stage so as to rotate the Echelle grating from the Littrow arrangement by a predetermined angle &dgr;1. On the other hand, in the case where a double pass beam is to be detected, the control processing unit controls the rotation stage so as to rotate the Echelle grating from the Littrow arrangement by a predetermined angle &dgr;2.

Abstract: The invention describes an optical network architecture which uses a limited number of wavelength channels while providing flexible connections between the network nodes. Each node in the network deploys a fixed wavelength transmitter and a fixed wavelength receiver, whose wavelengths are misarranged so that a set of wavelengths of the transmitter differs from the set of wavelengths of the receiver, and wavelengths of transmitters and receivers at different nodes are arranged so that for any pair of nodes there is at least one common wavelength which is the same for one of the transmitter and receiver at one node and one of the respective receiver and transmitter at the other node, thus providing a direct connection between the nodes. The corresponding structure of optical add/drop multiplexer/demultiplexer for use at the network node, and method of providing direct connections between the nodes, are also provided.