Abstract: In aligning ends of optical fibers (13), e.g. for performing a prealignment of ends of large mode area double-clad fibers (LMA-DCFs) in order to thereafter perform a core alignment process, in a fiber optic fusion splicer a best, optimum or near optimum position or setting of the optical system (7) for observing the self-focusing effect is first determined and then the very alignment operation may be performed using the determined setting. The very alignment process may then be performed by adjusting stepwise the offset distance between the observed fiber ends by e.g. using a cascade technique.

Abstract: The present invention relates to a method for accurately calibrating fusion temperature in optical fiber splicing. With assistance of direct arc-recentering technique, two optical fibers are spliced and then continuously heated with a post-fusion process. In the process, the fusion temperature is automatically determined in terms of effective fusion currents, which is done by real-time monitoring the fusion time dependence of cladding diameter reduction. In comparison with model calculations, variations of fusion temperature caused by changes of electrode condition and operating environment, e.g. altitude, temperature and humidity are derived. To recover the optimal fusion temperature in various fusion processes, the calibrating results are automatically invoked to compensate fusion currents.

Abstract: When an optical fiber (1, 1?) is heated by an electrical discharge generated between electrodes (3) thermal light emission from the core and cladding of fiber forms a hot image which can be observed by an optical imaging system (9, 15, 17). Since the concentration of dopants in the core is significantly higher than in the cladding, the light emitted from the core gives a peak structure in the light intensity profile of a hot image. The peak width of the core image increases significantly when dopants diffuse out of the core such as in heating the fiber. The increase of peak width is found to be highly correlated to the expansion of the mode field diameter (MFD) of fiber. This correlation can be experimentally determined at well-defined fusion conditions for any given type of fiber and thereby used to give a measure of the MFD by observing the peak width in hot images. Measures of MFD can be used for improving the quality of estimation of losses in splices of optical fibers.

Abstract: A solid oxide fuel cell stack of modularized design is disclosed, which comprises: at least a fuel cell cassette; an air tank, for providing air to the fuel cell stack while being used for receiving the fuel cell cassette; a fuel tank, for providing fuel to the fuel cell stack; and a set of conducting strips, connecting to the fuel cell cassette for transmitting electricity out of the fuel cell stack; wherein the fuel cell cassette further comprises a planar fuel cell and a case, being used for receiving the planar fuel cell. Preferably, the planar fuel cell is composed of two membrane electrode assembly (MEA), each having an anode electrode, a cathode electrode, and a nickel mesh with an extending bar, sandwiched between the two MEAs, whereas the anode electrode of one of the two MEAs is placed facing the anode electrode of another MEA.

Abstract: The present invention relates to a solid oxide fuel cell, which comprises: a plurality of tubular electrodes, reacting gases supplying means, and a preheat piping. The tubular electrodes are concentrically arranged while enabling the polarity of a surface of any one of the plural electrodes is the same as that of the corresponding surface of a neighbor electrode faced thereto; wherein each tubular electrode further comprises an anode layer, a cathode layer, and a solid electrolyte layer sandwiched between the anode layer and the cathode layer. The supplying reacting gases means is capable of supplying fuel and gas respectively to the anode and cathode of the tubular electrodes. The preheat piping, connected to the supplying reacting gases means, collects the heat generated from the combustion reaction of residual fuel and gas, which can be utilized to preheat the gases supplying reacting means.

Abstract: Optical fibers (1, 1?) are fusion spliced to each other by using a CO2 laser (109) having an emission wavelength of 9.3 microm. The heat absorption of the fibers is higher and the variation of the absorption for small deviations of the wavelength is smaller than at the conventional wavelength of 10.6 microm. As a result, less laser power is needed, the laser construction may be more compact and safety problems can easier be handled. The optical arrangement for the light beam of the CO2 laser includes deflecting and focusing the collimated laser beam (20) emitted by the laser using a mirror (10) having a curved surface of concave nearly paraboloid shape, the splice position (30) located at a small distance of the focus of the mirror and well outside the collimated beam.

Abstract: A technique is provided for automatic optimization of a splice loss estimator of a fiber splicer (1), where the splice loss estimator is adapted, in a splice loss estimation procedure, to estimate the splice losses (Lti) of splices (i) of optical fibers as produced by the fiber splicer from images taken of the optical fibers at the splicing thereof, and the splice loss estimation procedure includes the use of splice loss estimation parameters (Pj). The estimator estimates splice losses based on information (Cij) obtained from the images and the estimation parameters. Further, the splice losses are measured by means of a measurement instrument (3). The estimated (Lti) and measured (LMi) splice losses, and the information obtained from the images are uploaded (71) into an off-line computer (5) and the key estimation parameters are automatically optimized by the selection of any solution within the Bellcore accuracy criteria (75), whereafter the optimized estimation parameters are downloaded (81) to the splicer.

Abstract: The present invention relates to a method for accurately calibrating fusion temperature in optical fiber splicing. With assistance of direct arc-recentering technique, two optical fibers are spliced and then continuously heated with a post-fusion process. In the process, the fusion temperature is automatically determined in terms of effective fusion currents, which is done by real-time monitoring the fusion time dependence of cladding diameter reduction. In comparison with model calculations, variations of fusion temperature caused by changes of electrode condition and operating environment, e.g. altitude, temperature and humidity are derived. To recover the optimal fusion temperature in various fusion processes, the calibrating results are automatically invoked to compensate fusion currents.

Abstract: When an optical fiber (1, 1?) is heated by an electrical discharge generated between electrodes (3) thermal light emission from the core and cladding of fiber forms a hot image which can be observed by an optical imaging system (9, 15, 17). Since the concentration of dopants in the core is significantly higher than in the cladding, the light emitted from the core gives a peak structure in the light intensity profile of a hot image. The peak width of the core image increases significantly when dopants diffuse out of the core such as in heating the fiber. The increase of peak width is found to be highly correlated to the expansion of the mode field diameter (MFD) of fiber. This correlation can be experimentally determined at well-defined fusion conditions for any given type of fiber and thereby used to give a measure of the MFD by observing the peak width in hot images. Measures of MFD can be used for improving the quality of estimation of losses in splices of optical fibers.

Abstract: The polarization axes of the ends of two PM fibers are aligned in an automatic fiber splicer by first making a linear alignment of the fiber ends (1, 1?) using movable retainers (21) the same way as for conventional splicing. The fiber ends are rotated by rotatable fixtures (22) to capture images by a camera (9) and therefrom, in an image processing and analysis unit (15), as controlled by logical circuits (33) light contrast profiles are determined as functions of the angular position. From the light contrast profiles the polarization axes are determined and then they are aligned with each other. The images are captured of an area at and around the fiber ends as seen in an observation plane. This observation plane is taken to have such a position that the variation of the light contrast profiles is sufficiently large, this making the determination of the angular positions of the polarization axes have a sufficient accuracy, also for for example elliptical core fibers.

Abstract: A method and arrangement for achieving low splice-losses when connecting Highly Rare-Earth-Doped (HRED) optical fibers and dissimilar optical fibers having a large Mode Field Diameter (MFD) mismatch. Warm images are taken during a pre-fusion process to capture thermal light emissions and determine an arc-center position. The end-surfaces of the fibers are abutted and longitudinally offset from the arc-center, based on the light propagation direction and the MFD-mismatch. The fibers are then asymmetrically heated with different fusion temperatures during the main fusion processes. An MFD-match is achieved with well-defined fusion currents and fusion time. To maintain the same offset distance in a sequence of splices, the main-fusion arc-center position is determined by a process of direct arc-recentering.

Abstract: In a device (100) for continuously varying the extinction ratio, ER, a laser diode (102) is connected to a first end of a PZ fiber (108). At a second end, the PZ fiber is connected to a connector (110). At the other end of the connector a PM fiber (106) is connected. The two fibers meet in the connector, which means that opposite end facets of the fibers are located at a very close distance of each other. A rotation is produced by a rotator (104), mechanically coupled to the connector. The device can be used for: selecting a desired ER of the PM fiber; achieving high accuracy of angular alignment between the principal axes of two PM fibers (106, 506); evaluating the quality of angular alignment of a splice between two PM fibers made by a splicer; and setting the adjustment/calibration of a PM fiber.

Abstract: The polarization axes of the ends of two PM fibers are aligned in an automatic fiber splicer by first making a linear alignment of the fiber ends (1, 1?) using movable retainers (21) the same way as for conventional splicing. The fiber ends are rotated by rotatable fixtures (22) to capture images by a camera (9) and therefrom, in an image processing and analysis unit (15), as controlled by logical circuits (33) light contrast profiles are determined as functions of the angular position. From the light contrast profiles the polarization axes are determined and then they are aligned with each other. The images are captured of an area at and around the fiber ends as seen in an observation plane. This observation plane is taken to have such a position that the variation of the light contrast profiles is sufficiently large, this making the determination of the angular positions of the polarization axes have a sufficient accuracy, also for for example elliptical core fibers.

Abstract: Optical fibers (1, 1?) are fusion spliced to each other by using a CO2 laser (109) having an emission wavelength of 9.3 ?m. The heat absorption of the fibers is higher and the variation of the absorption for small deviations of the wavelength is smaller than at the conventional wavelength of 10.6 ?m. As a result, less laser power is needed, the laser construction may be more compact and safety problems can easier be handled. The optical arrangement for the light beam of the CO2 laser includes deflecting and focusing the collimated laser beam (20) emitted by the laser using a mirror (10) having a curved surface of concave nearly paraboloid shape. the splice position (30) located at a small distance of the focus of the mirror and well outside the collimated beam.

Abstract: A technique is provided for automatic optimization of a splice loss estimator of a fiber splicer (1), where the splice loss estimator is adapted, in a splice loss estimation procedure, to estimate the splice losses (Lti) of splices (i) of optical fibers as produced by the fiber splicer from images taken of the optical fibers at the splicing thereof, and the splice loss estimation procedure includes the use of splice loss estimation parameters (Pj). The estimator estimates splice losses based on information (Cij) obtained from the images and the estimation parameters. Further, the splice losses are measured by means of a measurement instrument (3). The estimated (Lti) and measured (LMi) splice losses, and the information obtained from the images are uploaded (71) into an off-line computer (5) and the key estimation parameters are automatically optimized by the selection of any solution within the Bellcore accuracy criteria (75), whereafter the optimized estimation parameters are downloaded (81) to the splicer.

Abstract: A method and arrangement for achieving low splice-losses when connecting Highly Rare-Earth-Doped (HRED) optical fibers and dissimilar optical fibers having a large Mode Field Diameter (MFD) mismatch. Warm images are taken during a pre-fusion process to capture thermal light emissions and determine an arc-center position. The end-surfaces of the fibers are abutted and longitudinally offset from the arc-center, based on the light propagation direction and the MFD-mismatch. The fibers are then asymmetrically heated with different fusion temperatures during the main fusion processes. An MFD-match is achieved with well-defined fusion currents and fusion time. To maintain the same offset distance in a sequence of splices, the main-fusion arc-center position is determined by a process of direct arc-recentering.

Abstract: In splicing two optical fibers to each other using an electric arc formed between electrodes images of the regions being heated and thereby fusioned to each other are taken. The images cover a rectangular field (43) having the fibers located centrally, along a center line of the field and parallel to the long sides of the field. The images are evaluated to determine a value of the position of the center of the electric arc in relation to the position of the end surfaces of the fibers. This value can then be used for placing the end surfaces just at the arc center. In the image the image of the optical fibers can be excluded so that only light intensity from the air discharge of the electric arc is recorded in the captured images. The field (41) excluded can be a narrow strip of uniform width located symmetrically around the image of the fibers.

Abstract: In a device (100) for continuously varying the extinction ratio, ER, a laser diode (102) is connected to a first end of a PZ fiber (108). At a second end, the PZ fiber is connected to a connector (110). At the other end of the connector a PM fiber (106) is connected. The two fibers meet in the connector, which means that opposite end facets of the fibers are located at a very close distance of each other. A rotation is produced by a rotator (104), mechanically coupled to the connector. The device can be used for: selecting a desired ER of the PM fiber; achieving high accuracy of angular alignment between the principal axes of two PM fibers (106, 506); evaluating the quality of angular alignment of a splice between two PM fibers made by a splicer; and setting the adjustment/calibration of PM fiber.

Abstract: A strongly confined ridge waveguide that provides substantially reduced polarization sensitivity, without significant compromise for other waveguide characteristics such as, for example, single-mode condition, and low propagation and bending losses for the fundamental mode. The present invention considers waveguide material composition and thickness for guiding and cladding layers, bend radius, ridge width and etch depth at which the modal indices of the fundamental TE and TM modes are equal. With those parameters, the losses (e.g., the imaginary parts of the modal indices) of the fundamental and first-order modes may be calculated. By considering the previously mentioned criteria, a low-loss, single-mode ridge waveguide may be constructed in accordance with the present invention having losses of the fundamental modes in the range of less than approximately 1.

Abstract: A guided wave optical switch having a passive optical component optically coupled to a low gain optical amplifier—both being formed monolithically in a semiconductor substrate. The passive optical component may comprise a single-mode −3 dB optical power splitter that receives at an input an optical signal and splits that optical signal approximately equally between two outputs. The passive optical component may also comprise an optical isolator, an optical circulator, and other known passive optical devices. The low gain optical amplifier includes a waveguide having an active region that may provide optical signal gain when excited by an electrical current provided by a metal or metallic electrode connected to the active region. The active region may be a bulk active region, a multiple quantum well active region, or the waveguide may comprise a buried heterojunction waveguide having either a bulk or multiple quantum well active region.