Abstract: A single wafered optical fiber ferrule assembly useful in fixed and tunable fiber Fabry-Perot (FFP) filters is described. The ferrule assembly contains a wafered ferrule with embedded mirror and a mirrored-end ferrule which are aligned with respect to each other along a longitudinal axis in an alignment fixture. The ferrules are aligned and spaced with respect to each other to maximize transmission of light of a selected wavelength through the filter. The wafered ferrule is composed of a fiber ferrule and a wafer greater than or equal to about 5 .mu.m in thickness which are bonded together with a mirror embedded between the wafer and the ferrule. The ferrule assembly forms a FP optical resonance cavity between the two mirrors. The single wafered ferrule design produces more easily manufactured and more stable FFP than prior art designs.

Abstract: A fiber optic Fabry-Perot etalon filter constructed with a resonance cavity which is variable in length to enable variations in temperature to tune the filter to a desired frequency while maintaining accurate alignment of the fiber across the filter. Each fiber end is encased in a ferrule with the two ends placed in a facing relationship. The fibers are aligned and held by an appropriate fixture designed to allow a portion of the ferrule assembly containing the resonance cavity to expand or contract with temperature variation. The two mirrors defining the nominal size of the resonance cavity may be deposited on the facing end of each of the two ferrules, on an end of a separate waveguide located between the ends of the ferrules, or on any combination of these elements. Ferrules may be wafered, that is, a wafer of material may be bonded to the mirrored end of one or both ferrules.

Abstract: A low loss, tunable optical filter (20) comprises two ferrules (24-24) which are aligned axially with each of two adjacent end faces being provided with a wafer (30). A mirror (40) is embedded between each end face and its associated wafer, the wafer being bonded to the end face of its associated wafer. Optical fiber is disposed in a passageway which extends through each ferrule and through the associated wafer. The ferrules and associated wafers are supported to cause adjacent exposed faces of the wafers to be in predetermined spatial relation to each other. Any gap therebetween may be fixed or may be adjusted by a piezoelectric transducer system (44). The disclosed filter provides rejection ratios which are sufficiently high for frequency discrimination in frequency shift keying systems and for channel selection or switching in wave division multiplexer applications.

Abstract: A tunable fiber Farby-Perot interferometer includes two aligned ferrule assemblies (22--22) having adjacent end faces separated by a gap. Each assembly includes a mirror (40) disposed transverse to a longitudinal axis (28) of the assembly and embedded internally therein adjacent to the exposed end surfaces which defines the gap. Each ferrule assembly is held in a sleeve (74) disposed in an end fixture (70) with a piezoelectric transducer system (44) extending between end fixtures. Means (82--82) are provided in each end fixture for deforming slightly the sleeve to cause the ferrule assembly disposed therein to be moved into alignment with the other. The transducer system is operated to adjust the length of the gap between the exposed adjacent end faces. Also, the facilities including the transducer system are provided such that a portion or portions of it may be operated selectively to fine tune further the alignment between the fibers.

Abstract: A low loss, tunable optical filter (20) comprises two ferrules (24--24) which are aligned axially with each of two adjacent end faces being provided with a wafer (30). A mirror (40) is embedded between each end face and its associated wafer, the wafer being bonded to the end face of its associated wafer. Optical fiber is disposed in a passageway which extends through each ferrule and through the associated wafer. The ferrules and associated wafers are supported to cause adjacent exposed faces of the wafers to be in predetermined spatial relation to each other. Any gap therebetween may be fixed or may be adjusted by a piezoelectric transducer system (44). The disclosed filter provides rejection ratios which are sufficiently high for frequency discrimination in frequency shift keying systems and for channel selection or switching in wave division multiplexer applications.

Abstract: A multi-port optical device for transferring optical signals, or portion of optical signals, from one transmission element to another is disclosed. The inventive optical device comprises a pair of graded index lenses having an interposed Fabry Perot etalon. Moreover, the functionality of the device may be modified by varying the transmission characteristics of the etalon, which may be effected by varying the optical path length of the etalon. In operation, the optical device utilizes the graded index lenses as image transfer lenses between transmission elements wherein wavelength selectivity therebetween is afforded by the filtering mechanism associated with the etalon. The optical device may be used as a wavelength multiplexer or as an optical splitter. Moreover, by utilizing a piezoelectric transducer, the optical device may be converted to operate as an optical switch.

Abstract: Disclosed is an optical fiber connector that comprises two right capillary cylinders or "plugs", an alignment sleeve that contactingly maintains the plugs in substantially fixed relative relation, and means for maintaining the plugs in substantially fixed relative axial relation. Connectors according to the invention can have very low insertion loss, are easily field-installed, can be easily and relatively inexpensively manufactured, and are useful for single mode as well as for multimode fiber applications. In a preferred embodiment the connector takes the form of the ST.RTM. connector.

Abstract: A mechanical connection arrangement for two polarization-maintaining optical fibers (20--20) includes two ferrules (40--40). Each of the optical fibers to be connected includes an outer cladding layer (23) having a hybrid cross section transverse to a longitudinal axis of the fiber. The hybrid cross section is defined by two parallel sides and by two generally arcuate end portions. One of the polarization axes of the fiber is parallel to the parallel sides of the fiber. The ferrules were adjacent portions in a length (110) of stock material and are positioned in support means such that end faces of the ferrules which were contiguous to each other prior to the ferrules being separated from the length of material are adjacent to each other in the connection arrangement. Each ferrule prior to separation has a tab (126) associated therewith such that the tab of the adjacent portions are aligned longitudinally.

Abstract: Disclosed is an optical fiber connector that comprises two right circular glass tubular cylinders, means for maintaining the cylinders in substantially fixed relative radial relation, and means for maintaining the cylinders in substantially fixed relative axial relation. The fiber ends that are to be connected are maintained in the bores of the respective glass cylinders by UV-curable adhesive means. Connectors according to the invention can have very low insertion loss, are easily field-installed, can be easily and inexpensively manufactured, and are useful for single mode as well as for multimode fiber applications.

Abstract: The optical fiber connector comprises two right circular drawn glass capillary cylinders, means for maintaining the cylinders in substantially fixed relative radial relation, and means for maintaining the cylinders in substantially fixed relative axial relation. The invention has a multiplicity of embodiments, including connectors functioning as variable attenuators, as fiber-to-fiber switches and connectors comprising an in-line filtering element. Connectors according to the invention can have very low insertion loss, are easily field-installed, can be easily and inexpensively manufactured, and are useful for single mode as well as for multimode fiber applications.

Abstract: Light guided by an optical fiber is tapped by bending the fiber, and substantially surrounding a portion of the fiber with a tube that couples a portion of the optical energy to a detector. The tube can be bent to increase the efficiency of collection of optical energy. The tube can be tapered to improve coupling to small detectors. The loss introduced by the tap is typically in the range of 0.001 to 1.0 dB, and the collection efficiency is high. The technique can be used for single mode or multimode optical fibers, and the fiber can typically remain coated. A large number of taps, typically several hundred, can be applied or removed without disrupting a signal carried by an optical fiber.

Abstract: In a plug-type optical fiber connector low loss can be achieved, without any active alignment of the fiber cores, if the two cylindrical plugs used in the connector are "contiguous" plugs, i.e., derived from contiguous segments of the tubular stock from which the plugs are produced, and if the plugs are arranged such that the "contiguous" ends of the plugs are the mating ends, and such that the rotational relationship between the plugs is substantially the one that existed prior to sectioning. The inventive connector comprises two contiguous plugs and includes features that permit identification of the contiguous ends and of the rotational relationship. In a preferred embodiment, the tubular stock is drawn glass stock, the two contiguous segments are left joined but scored circumferentially to permit easy separation in the field, with a longitudinal groove in the outer cylinder surface of the contiguous segments identifying the original rotational relationship.

Abstract: An optical fiber connector capable of producing very low-loss single-mode fiber connections is disclosed. The connector utilizes two capillary cylinders for holding the fiber ends, and a multiplicity, preferably three, cylindrical alignment rods that provide multi-point support for the cylinders. At least one, preferably two, of the alignment rods carry a "flat" extending from one end of the rod for a substantial fraction of the length of the rod. The assembly is held together by appropriate means, e.g., a substantially triangular alignment fixture. The presence of antiparallel flat-carrying alignment rods permits simple alignment of the two fiber cores, typically by means of rotation of one or both of the capillary cylinders.

Abstract: Optical fibers are spliced by a technique that yields very low loss and accommodates fibers having different outer diameters or having nonconcentric cores. The technique is especially useful for single mode optical fibers, and splice losses of less than 0.1 db in a wavelength range of about 1.3 to 1.55 micrometers is typically obtained. The splice comprises a slotted tube surrounding abutted fiber ends, with the tube being at least partially filled with cement. An outer cylindrical sleeve is optionally provided for increased strength. In splicing the fibers, the fibers are aligned by means of a scattered light detector comprising a slotted tube surrounding a portion of the fiber, and a detector at one end of the tube. A sensitive null indication is obtained which provides for precise alignment of the fiber cores.

Abstract: A method of forming optical fibers with improved mode dispersion characteristics is disclosed. The technique involves differential mode-group delay measurement to optimize dispersion by means of appropriate index of refraction configurations. The differential delay measurement technique involves selectively launching light into the multimode fiber using a single mode fiber which is spliced to the multimode fiber using an adjustable splice including an index matching fluid.

Abstract: A device (70) for switching optical signal paths of the type utilizing a plurality of light-transmitting optical fibers (40, 50) comprises a flexible elongated sleeve (20) having a longitudinally continuous interior cross section (24) with a plurality of corners (30) forming fiber-aligning grooves. The sleeve loosely receives a first fiber (40) from a first sleeve end (26) and a plurality of second fibers (50) from a second sleeve end (28). Each second fiber has its coupling end biased against an assigned corner. Also, the ends of all the second fibers are contained in one transverse plane (23). The coupling end (46) of the first fiber adjacent the transverse plane and a portion (42) of the first fiber, remote from its end, is fixedly secured to the sleeve. Coupling of the first fiber with any of the second fibers is achieved by flexing the sleeve to move the first fiber end to the corner containing the selected second fiber.