Abstract:
A wavelength filtering device and system in which an optical resonant cavity is laterally coupled to a trunk waveguide carrying a broad range of wavelengths in the optical spectrum. The filtering cavities may be linear optical fiber segments or fiber segments closed at their ends in the shape of a loop. The devices may include single or multiple optical cavities or hybrid filtering utilizing both dispersive and resonant functions.
Abstract:
An optical fiber structure having resonant characteristics useful for coupling to an optical transmission line for removing selected wavelengths of light energy includes a light guiding structure, such as an optical fiber waveguide, which conditionally operates as a resonant cavity responsive to resonance of at least one other resonant cavity. In one embodiment, an extrinsically defined or adscititious reflectance is formed in the waveguide segment by laterally coupling an etalon cavity to the waveguide segment. In another embodiment, the waveguide segment is coupled to one or more resonant loops to form a conditional resonant loop cavity which includes the other loops. The resonant wavelength spacing for the conditional cavity and its cooperating resonant cavity are made different from one another with only one wavelength coresonantly supported in both cavities. In operation, the structure is coupled to a multi-channel optical transmission line for selectively removing a portion of the energy of a desired channel by resonating the desired wavelength in both the conditional cavity and its cooperating resonant cavity. Additionally, an active gain material can be provided in the conditional cavity and pumped by a pumping source to increase the gain of the desired wavelength.
Abstract:
A method for fabricating preforms for drawing into single mode optical fibers having core and cladding doped with different amounts fluorine. A pure fused silica start rod is first coated with a layer of soot which is then dehydrated, doped with a first level of fluorine, and then consolidated. This structure, which is an intermediate preform, is then drawn down until its area weighted average index of refraction is such that it would perform as a core in a fiber. If not, it is recoated and drawn down further until it will behave as a core upon further reduction in size. The intermediate preform is then recoated with another layer doped with a higher concentration of fluorine so that it will act as a cladding layer over the first fluorinated layer whose index is higher because of a lower concentration of fluorine. This final structure serves as a preform from which the desired fiber can be drawn.
Abstract:
An electronic camera tube includes a transparent envelope enclosing an evacuated cavity, a photocathode layer on a first internal surface of the envelope and an array of storage electrodes on a second internal surface of the envelope. The first and second surfaces are parallel and closely spaced. The photocathode layer emits electrons in response to an incident light intensity pattern. The storage electrodes in the array receive the electrons from the photocathode layer and emit secondary electrons, thereby accumulating a charge pattern representing the light intensity pattern. The camera tube further includes a readout device associated with each storage electrode for reading out the charge pattern during a readout phase. The readout devices operate by generating a readout current through an evacuated region adjacent to each storage electrode. Each readout current is a function of the charge accumulated on the adjacent storage electrode during the exposure phase. A number of different readout techniques can be utilized.
Abstract:
An electronic camera tube includes a transparent envelope enclosing an evacuated cavity, a photocathode layer on a first internal surface of the envelope and an array of cells on a second internal surface of the envelope. The first and second surfaces are parallel and closely spaced. The photocathode layer emits electrons in response to an incident light intensity pattern. The cells in the array receive the electrons from the photocathode layer and emit secondary electrons, thereby accumulating a charge pattern representing the light intensity pattern. The camera tube further includes readout devices for reading out the charge pattern during a readout phase. The readout devices operate by electron tunneling and inject electrons perpendicular to the cell array through the evacuated cavity to readout electrodes on the photocathode layer. The electron currents injected through the evacuated cavity by the readout devices are controlled in response to the charge on the respective cells in the array.
Abstract:
A single-mode optical fiber transmission line suited for coupling to another fiber through a laterally coupled splice includes a core having a selected diameter, a cladding layer that surrounds the core and has a cladding thickness between one and two core diameters, and an auxiliary cladding into which the optical fiber is nested. The auxiliary cladding has an index of refraction not substantially greater than that of the cladding layer that surrounds the core, an inside dimension greater than that of the outside dimension of the optical fiber, at least partially surrounds the optical fiber and is attached to the optical fiber at least along one lineal connection zone. An optical fiber in accordance with the present invention may be spliced by freeing the optical fiber from the auxiliary cladding by, for example, dissolving the lineal connection zone with dilute hydrofluoric acid, fracturing and removing the auxiliary cladding from the freed cladding and core structure and effecting a lateral coupling splice with a similarly prepared optical fiber.
Abstract:
A sensor or transducer having a dual path optical fiber, such as a single mode, two polarization state, waveguide fiber, utilizes the relative change in propagation constant of the paths to sense and transduce an applied force to an interference variation and ultimately an electrical signal. In this arrangement, in-phase light is introduced to both polarized states or paths in the fiber and transmitted therealong past a stress area of birefringement inducing force and ultimately combined, thereby producing in the combined beam a variation in interference which is related to the applied force. Specific structures are provided for converting isotropic forces such as pressure and temperature to anisotropic forces on the fiber to thereby produce birefringement and to also magnify the latter effect.
Abstract:
A method for forming an optical fiber from a single characteristic glass includes arraying hollow starter tubes about a central axis with each starter tube contacting its adjoining tubes along respective lines of contact to define a longitudinally extending opening about the central axis. The arrayed starter tubes are heated to cause them to fuse together along their lines of contact, and the fused starter tubes are inserted into a jacketing tube, preferably having the same physical and optical properties as the starter tubes. A pressure differential is established between the interior of the starter tubes and the tube-defined longitudinally extending opening. The tube assembly is heated to allow the established pressure differential to cause portions of the starter tubes to reform by moving toward and to the central axis to create a solid, void-free core and supporting webs. Other portions of the starter tubes expand toward and fuse to the interior surface of the jacketing tube. The resulting optical fiber has a central core supported from the interior of jacketing tube by the starter tube-defined webs with all the structural features of the fiber formed from a glass having the same physical and optical properties.
Abstract:
A fiber optics polarizer, wherein a multi-core polarization element is inserted to a fiber communications line and a signal to be communicated through the polarizer is carried by a first core and the other polarizations are coupled from the first core into one or more other cores to prevent propagation through the system.
Abstract:
An improved method of forming an optical fiber preform includes separately forming a rod-like inner member and a hollow tube-like outer member by a soot glass deposition technique. The inner member is inserted into the outer member, while they are both in their unconsolidated state, and the asssembled parts heated to cause the outer member to collapse about the inner member and form a preform. The resulting preform can be drawn in one or more stages to provide an optical fiber having sharp step change in its index of refraction between the core and the cladding, a superior quality core to cladding interface, and improved optical transmission qualities. The inner and outer members can, if desired, be partially consolidated but for an unconsolidated layer at their interface prior to heating the outer member to cause it to join with the inner member. In accordance with one feature of the present invention, an unconsolidated layer can be left on the outside surface of the outer member to provide a resulting fiber having superior mechanical handling characteristics.