Abstract: We have discovered that silica-based optical fibers that are doped with Ge, Al and a rare earth (e.g., Er) can be very susceptible to hydrogen-induced attenuation change. For instance, such fiber can exhibit loss increase rates that are, at 20.degree. C., 10.sup.6 times larger than those of a standard single mode fiber. We also believe that transition metal-doped silica-based fibers can exhibit large hydrogen-induced attenuation change. In many circumstances (e.g., amplifier fiber, attenuator fiber) significant attenuation change of optical fiber is undesirable. We disclose that such change can be substantially eliminated by provision of hydrogen gettering material and/or a "hermetic" fiber coating. It is currently preferred to provide silica cladding material that is a hydrogen getter, and also provide a "hermetic" fiber coating. Containment of the fiber, together with a quantity of a gettering material (e.g., ErFe.sub.2) in an essentially hermetic enclosure is also disclosed.

Abstract: Optical waveguide amplifiers and lasers having a novel fluorescent dopant distribution are disclosed. Exemplarily, in a Si-based optical fiber the fluorescent dopant (e.g., Er) has an annular distribution, with the concentration maximum not at the center of the core but typically between the center and the core/cladding interface. The novel waveguides can be relatively insensitive to variations in cut-off wavelength and/or modal distribution of pump power.

Abstract: Unexpectedly large normalized refractive index changes (.DELTA.>10.sup.-5, but possibly even larger than 10.sup.-3) can be obtained in SiO.sub.2 -based optical waveguides (fiber or planar waveguides) by a treatment that comprises exposing at least a portion of the waveguide at a temperature of at most 250.degree. C. to H.sub.2 (partial pressure greater than 1 atmosphere), and irradiating at least a part of the exposed portion with actinic (typically UV) radiation.

Abstract: This invention is a process of contactless monitoring the tension in a moving fiber, such as during the process of drawing optical fibers from preforms, and a non-contacting tension gauge which allows measurement of fiber tension at line speed. The device can be used to monitor the tension during the run without any adverse effects on fiber performance. The measurement may be steady, intermittent or sinusoidal as appropriate. The process includes the steps of sensing an initial position of a moving optical fiber, applying a gas jet onto a section of the optical fiber in a direction transverse to the direction of movement of the fiber so as to cause deflection of the moving fiber axially of the gas jet, sensing the magnitude of deflection of the fiber relative to the said initial position, and, depending on the magnitude of deflection, adjusting the tension in the fiber so as to cause the change in the magnitude of deflection to a preselected value.

Abstract: Germanosilicate optical fiber having substantially higher GeO/GeO.sub.2 ratio than conventional comparison-fiber is disclosed. The fiber has a loss at wavelength of 330 nm of at least 30 db/m.mole % GeO.sub.2. Such fiber can be advantageously used for making in line photorefractive Bragg gratings and other photorefractive fiber components. Fiber according to the invention can be produced by an inside deposition process (e.g., MCVD, PCVD), by an outside deposition process (e.g., VAD, OVD), or even a sol/gel process, and embodiments of the general method of making fiber according to the invention are disclosed.

Abstract: Disclosed is an optical communication system comprising at least two optical fibers of dissimilar core sizes, joined by a fusion splice. In one embodiment, the larger-core fiber is a communication fiber, and the smaller-core fiber is an erbium-doped amplifier fiber. A taper region is included adjacent the splice. The diameter of the smaller-core fiber increases within the taper region as the splice is approached along the smaller-core fiber. The taper region is substantially free of constrictions. As a consequence of the taper region, the optical losses associated with the splice are relatively low, even when there is relatively high mismatch between the mode field diameters (at a signal wavelength) in the respective fibers.

Abstract: Reproducible doped optical fiber preforms having a predetermined dopant concentration level are fabricated by inserting a doped filament into a completed preform prior to consolidation and final collapse so that the filament and dopant materials are centrally located in the core region upon formation of the preform. Doped fiber is drawn from the doped preform using standard fiber drawing techniques.

Abstract: The inventive optical fiber communication system comprises Si-based amplifier fiber whose core comprises Ge, Al, and Er. The amplifier fiber has an effective index difference (.DELTA.n) greater than 0.03, an effective core diameter a less than 3.5 .mu.m, a maximum Al concentration in the core of at least 6 mole %, a mode field diameter at the pump wavelength that is less than 5 .mu.m, a V-number at the pump wavelength in the range 1.4-2.0, a cut-off wavelength less than 1.4 .mu.m, and an Er distribution whose effective diameter is less than that of the Ge distribution. The fiber has advantageous properties including low amplification threshold and noise. Disclosed is also a method of making optical fiber that can be used to produce fiber having characteristics (e.g., .DELTA.n>0.03, high Al concentration) not generally obtainable with prior art methods.

Abstract: The inventive method of producing optical fiber comprises producing a rod-like silica-based body, overcladding the body with pre-existing silica-based glass, and drawing fiber from the thus produced preform. The rod-like body comprises a core and a first cladding that surrounds the core, both consisting of deposited glass, and further comprises a second cladding that surrounds the first cladding and that is derived from a substrate tube that has a refractive index n.sub.2 <n.sub.0, the refractive index of vitreous silica. The overcladding comprises pre-existing glass, and comprises a third cladding region that has a refractive index n.sub.3 .ltoreq.n.sub.0. Typically, the overcladding material is derived from one or more overcladding tubes. The inventive method can be used to produce preforms capable of yielding more fiber than prior art rod-in-tube preforms, potentially resulting in significant cost reduction without performance penalties.

Abstract: Near uniform optical amplification is achieved in a lightwave transmission system in which a plurality of short lengths of rare earth doped silica-based fibers and a corresponding plurality of long lengths of substantially undoped silica-based fibers are interleaved to form a fiber span having alternating sections of compensated (moderate gain) and uncompensated lightwave transmission media. Pumping of the amplifying fiber sections is performed remotely from either end of the fiber span. Bidirectional pumping, that is, pumping from each end of the fiber span, enhances the uniformity of the optical amplification for signals over the entire span. Amplifying fiber section lengths are variable in substantially inverse proportion to dopant concentration within the particular section.

Abstract: A remotely controlled vehicle for traversing various terrains to accomplish missions in a hostile environment. This vehicle is sufficiently small so as to permit introduction into the environment through a manway, and is designed so that it can be operated while submersed. It has a main chassis with rotatable tracks on either side thereof that supports the vehicle. Auxiliary chassis in a forward and rearward direction also carry tracks on either side, with theses auxiliary chassis being pivotable to raised or lowered positions to accomplish movement over uneven terrain or for storage of the vehicle. All of the tracks on one side of the vehicle (main chassis track and tracks on forward and rearward auxiliary chassis) are rotated by a single drive mechanism within the main chassis, with the rotation of the tracks on the second side being rotated by another internal main drive mechanism. The pivotal movement of each of the auxiliary chassis is controlled by a separate drive mechanism.

Abstract: A hermetically coated optical fiber is produced by contacting a hot fiber with an organic material such as acetylene. The heat of the fiber causes decomposition and results in a hermetic, carbonaceous coating. This coating is essentially impermeable to both water and hydrogen.

Abstract: A remotely controlled vehicle for traversing various terrains to accomplish missions in a hostile environment. This remotely controlled vehicle has a main chassis with rotatable tracks on either side thereof that supports a central body of the vehicle. Auxiliary chassis in a forward and rearward direction also carry tracks on either side, with these auxiliary chassis being pivotable to raised or lowered positions to accomplish movement over uneven terrain. The body carriers a deployable arm including a shoulder, an elbow and a wrist, with this arm being provided with five degrees of motion. The drive means throughout the vehicle for the main tracks and for the essential components of the arm are carried out through the use of motor driven planetary gear assemblies to achieve the necessary torque and speed.

Abstract: A new method for fabricating devices which include multicomponent metal halide glasses, e.g., multicomponent metal halide glass optical fibers, is disclosed. In accordance with the inventive method, a multicomponent metal halide glass body, essentially free of crystallites, is produced by cooling essentially every portion of a melt incorporated into the glass body at a quench rate which is necessarily greater than or equal to about 10 Kelvins per second (K/sec). This necessary quench rate is achieved by successively quenching relatively small portions of the melt, e.g., thin layers or droplets of melt material, having relatively small cross-sectional dimensions.

Abstract: Certain dopant materials, when present in a significant power-carrying portion of a silica-based optical waveguide fiber, are effective as intrinsic loss-reducing agents; the concentration of such dopant materials is at significantly lower levels as compared with levels used for producing a refractive index difference. Suitable in this respect are germania and phosphorus pentoxide as added to essentially pure silica or to silica containing other dopant additives such as, e.g., alumina or fluorine as may be used in a waveguiding core-cladding structure. Intrinsic loss in the vicinity of 0.2 dB/km is readily realized.

Abstract: A mobile robot remotely controlled and/or powered through a cable from a stationary console is provided. The robot carries a cable management arrangement which stores the cable and dispenses and retracts it as needed. The arrangement lays down the cable under zero tension when the robot is outbound and reels it in as the robot returns to allow the robot to follow a tortuous path without entangling the cable under or around obstacles. The robot can have numerous configurations such as a simple configuration for use as a transporter for mail in an office and parts in a factory, to a complex configuration with robotic arms and sensors for use in remote surveillance and security work. The robot is especially usable in hostile environments such as nuclear power plants and has a containment box permitting it to be moved to numerous locations without contaminating other areas.

Abstract: Optical communication and sensing systems are disclosed which operate at long wavelengths, i.e., wavelengths greater than about 2 .mu.m, but less than or equal to about 11 .mu.m. Each of these systems includes an optical fiber having material, such as a metal halide glass, which is substantially transparent to long wavelength electromagnetic radiation. These optical fibers exhibit reduced microdeformation and macrobending losses, as well as low total dispersions, at the long wavelengths. In contrast to currently held beliefs, this is achieved by using fiber designs involving relatively small relative refractive index differences, which are readily manufacturable and which avoid undesirable crystallization at core-cladding interfaces.

Abstract: A safety grapple for releasably joining an object to be moved to a device for moving the same. Provision is made to cycle the grapple (10) through at least two release procedures before actual release can be effected. This is accomplished through the use of lug actuator cam plate 50 which rotates unidirectionally a selected amount for each upward and downward movement of a central shaft (22) of the grapple (10). This cam (50), with cam followers (52) mounted on the lugs (54), is shaped such that the lugs (54) are pivoted out of engagement with the object (100) only after a selected number of shaft reciprocations. In a specific embodiment, the grapple (10) requires two full cycles of shaft movement before lug release is effected on the third cycle. This prevents inadvertent release of the object (100), a feature especially important in the handling of hazardous material.

Abstract: Optical fibers doped with nonglass forming refractory oxides, such as alumina and zirconia, are disclosed. Devitrification is retarded by adding an additional glass forming component, such as P.sub.2 O.sub.5, and by rapidly quenching the heated glass. Aluminum and zirconium-containing precursor vapors are formed by passing halide gas over heated aluminum or zirconium wire.

Abstract: A device for effecting a link pipe seal between aligned portions of conduit. This device has a body portion (22) which may be affixed to any given structure and one portion of the tubing or piping (14) to be joined is clamped therein. The body provides for axial alignment of a second piece of tubing or piping (12) and carries a swing clamp (34) for engaging the second piece of tubing or piping whereby the second piece is moved axially toward the first piece to effect the seal. The motion of the swing clamp is accomplished by a left-handed threaded bolt (42), threadably engaged with the swing clamp and carried by the body as the pivot element for the swing clamp. Frictional engagement between the swing clamp and the threaded bolt brings about movement of the swing clamp between first and further preselected rotational positions as the bolt is rotated.