Abstract: An add/drop node of an optical WDN-network which has two fiber paths for light of a plurality of channels propagating in opposite directions comprises two add/drop modules (231, 23r) for each of the channels. All the modules are identically constructed. Each module comprises an add device (251, 25r) for adding light to one of the paths and a drop device (27r, 271) for deflecting a portion of light from a second one of the paths. A module comprises a house (41) enclosing the add device and the drop device. A first fixed connector (53, 73) is attached to the house for connection in the first path and to a an optical fiber (45, 65) which extends freely from the house and has a first free connector (43, 63) at its free end to be attached to the fixed connector of a neighboring add/drop module for continuing the first path through the considered add/drop module to the neighboring module.

Abstract: An add/drop node of an optical WDN-network which has two fiber paths for light of a plurality of channels propagating in opposite directions comprises two add/drop modules (231, 23r) for each of the channels. All the modules are identically constructed. Each module comprises an add device (251, 25r) for adding light to one of the paths and a drop device (27r, 271) for deflecting a portion of light from a second one of the paths. A module comprises a house (41) enclosing the add device and the drop device. A first fixed connector (53, 73) is attached to the house for connection in the first path and to a an optical fiber (45, 65) which extends freely from the house and has a first free connector (43, 63) at its free end to be attached to the fixed connector of a neighbouring add/drop module for continuing the first path through the considered add/drop module to the neighbouring module.

Abstract: An optical fiber splicing device has guide grooves for aligning fiber ends. The fibers ends are held in the grooves by hold-down means including cylindrical pressing surfaces which are capable of rotating freely. Due to the free rotation, when lowering the hold-down means to hold the fiber ends, no longitudinal displacement of the fiber ends will occur and the fiber ends maintain their initial positions. The fiber ends are, after the holding operation having been completed, moved linearly, sliding in the guide grooves, an accurate linear movement being obtained from double parallelogram structures. Electrodes between which an electric arc is formed for heating the fiber ends at a splice position to fusion splice them to each other are given accurate, predetermined positions by means of adjustable positioning rings mounted to the electrodes.

Abstract: An add/drop node used in an optical network having two fiber paths for carrying light corresponding to a plurality of channels in opposite directions may include a pair of add/drop modules that correspond to one of the plurality of channels. This arrangement advantageously provides a simple approach for connecting the components of an add/drop node.

Abstract: In splicing optical fibers using an electric glow discharge generated between electrodes, the electric power in the glow discharge is maintained constant at varying ambient conditions, such as a varying atmospheric pressure. A signal representing the welding voltage is tapped at the middle terminal of a voltage divider circuit, and a signal representing the welding current is produced over a resistor. The signals are inputs to a multiplying circuit, the output signal of which is fed to one input of a comparator. A reference voltage is fed to the other input of the comparator. The error voltage from the comparator is an input signal to a control circuit providing a control signal to circuits for generating the voltage between the electrodes.

Abstract: A compact fiber rotator has a guiding and support device (2) which comprises suction channels (17) formed in the angle of two blocks (3, 5), and a rotation device (32) which is attachable to the guide device (2) and comprises a house (33), a rotating toothed wheel part (37), a platform (31) attached thereto and an electric step motor (43). The fiber (1) is secured on the platform (31) by means of a standard fiber retainer (61) which is retained at the platform (31) by means of magnets (29), the rotating part (37) being located between the support (2) and the retainer (61). The suction channels (17) of the support device can be provided with a suitably low negative pressure, so that the fiber which is to be rotated and welded can be retained satisfactorily but still may be rotated against smooth surfaces of the angle of the blocks (3, 5).

Abstract: In joining an optical fiber containing twin cores to a corresponding optical fiber of standard type having a single core and having the same outer diameter, so that a core in the twin-core fiber is aligned with the core in the standard fiber, a conventional automatic splicing machine for optical fibers is used. The twin-core fiber is placed with its cores for instance located in a vertical plane. Then the fibers are spliced in a conventional manner with an alignment of the outer surfaces of the fiber ends and during the splicing procedure or from the finished splice the lateral offset of for instance the upper core of the twin-core fiber and the single core is determined. This can be carried out by capturing an image of the fiber splice in a heated state, when the splice is performed by fusion-welding. The determined offset value then gives the offset, which is to exist between the outer surfaces of the fiber ends for providing the correct alignment of the fiber cores.

Abstract: When splicing optical fibers of different kinds to each other by means of arc welding, a matching of the mode field diameters of the fibers is desired. This is accomplished by prolonging (period 55) the heating after making the splice (period 53). During the prolonged heating the hot-fiber indices of the two fiber ends are continuously determined. Either one of these indices or some suitable quantity derived therefrom is all the time compared to a threshold value and when it is reached the heating is stopped. The threshold value has been determined in a preceding stage using test fiber pieces of the same kind in a splicing operation with prolonged heating. Then, in such a threshold level determining stage in addition to the hot-fiber indices, the transmission of light is constantly measured during the heating and when it has its maximum value the corresponding hot-fiber indices are stored and used for deriving the threshold value. This method of matching mode field diameters is simple and takes a short time.

Abstract: Optical fiber attenuators are produced by splicing two fiber ends by melt-fusioning. The fiber ends are initially placed with a large lateral offset and the heating of the spliced portion is continued during a long time period to completely align the fiber ends, in particular the cores (3) and claddings (2) thereof, and to make material of the fibers cores (3) diffuse (23) into the neighbouring regions of the fiber claddings. By properly choosing the extended time for prolonged heating attenuators can be produced with a good repeatability. The prolonged heating period is significantly shortened by the use of a large initial offset.

Abstract: A compact fiber rotator has a guiding and support Device (2) which comprises suction channels (17) formed in the angle of two blocks (3, 5), and a rotation device (32) which is attachable to the guide device (2) and comprises a house (33), a rotating toothed wheel part (37), a platform (31) attached thereto and an electric step motor (43). The fiber (1) is secured on the platform (31) by means of a standard fiber retainer (61) which is retained at the platform (31) by means of magnets (29), the rotating part (37) being located between the support (2) and the retainer (61). The suction channels (17) of the support device can be provided with a suitably low negative pressure, so that the fiber which is to be rotated and welded can be retained satisfactorily but still may be rotated against smooth surfaces of the angle of the blocks (3, 5).

Abstract: In splicing discrete individual optical fibers to a fiber ribbon cable, a fiber organizer is used for placing the loose fibers in a retainer so that they are located exactly in the same way as in a fiber ribbon cable. The retainer is a separate part which is placed, with its lids in an open position, in a lower, centrally located portion of a main part of the device. The individual fibers are inserted, one by one, in vertical slots which are aligned with each other and are located at each end of the fiber organizer. By a movable, elastic heel they are fed into horizontal, slotshaped spaces having heights or widths adapted to the diameter of the fibers and formed between lower and upper surfaces. When all fibers have been fed into the slot, the retainer lids can be swung down so that the individual fibers are securely retained in the retainer.

Abstract: In the determination of the angular offset between axial asymmetries, in particular between optically inhomogeneous regions in optically transparent bodies, such as stress concentration zones of optical PM-fibers or fiber cores of optical twin core fibers, located in arbitrary angular start positions, the ends of the fibers are illuminated during rotations thereof to different angular positions around their longitudinal axes. For different angular positions the difference is then determined between light, which has passed through the fiber end and in its position corresponds to the central part of the fiber, and light, which has passed through the fiber end and in its position corresponds to the region of the fiber located immediately outside the central part. These differences, considered as functions of the rotation angle, constitute curves for the fiber ends.