Abstract: An optical article having a rare earth doped, fluorinated aluminosilicate glass core composition consisting essentially, in mole %, of:______________________________________ SiO.sub.2 0-90 GeO.sub.2 0-90 Na.sub.2 O 0-25 Li.sub.2 O 0-10 K.sub.2 O 0-25 Rb.sub.2 O 0-25 Cs.sub.2 O 0-25 Al.sub.2 O.sub.3 5-40 Ga.sub.2 O.sub.3 5-40 RE.sub.2 (1)O.sub.3 0-40 RE.sub.2 (2)O.sub.3 0-1 Er.sub.2 O.sub.3 0.001-5 Yb.sub.2 O.sub.3 0-5 PbO 0-15 RO 0-20 ZnO 0-10 ZrO.sub.2 0-2 TiO.sub.2 0-2 Nb.sub.2 O.sub.5 0-10 Ta.sub.2 O.sub.5 0-10 P.sub.2 O.sub.5 0-5 B.sub.2 O.sub.3 0-15 As.sub.2 O.sub.3 0-10 Sb.sub.2 O.sub.3 0-20 Na.sub.2 Cl.sub.2 0-10 Bi.sub.2 O.sub.3 0-5, and ______________________________________up to 15 weight % fluorine in the form of at least one of a fluorinated component of the glass composition and a batch constituent selected from a group consisting of at least one of AlF.sub.3, REF.sub.3, NH.sub.5 F.sub.2, NaF, Na.sub.2 SiF.sub.6, Na.sub.3 AlF.sub.

Abstract: An external cavity, single mode laser has a semiconductor gain medium, such as a diode laser, and a monolithic prism assembly positioned in an external resonant cavity having a length of 10 mm or less. The monolithic prism assembly includes a transparent substrate carrying a thin film Fabry-Perot interference filter on a face which is tilted to the path of travel of the laser light in the external cavity. Translation of the monolithic prism assembly including transversely to the optical axis provides continuous mode-hop-free tuning of the laser output wavelength. The Such optical devices can be economically mass produced in advantageously small size, having reproducible spectral performance properties held within tight tolerances. Significantly advantageous applications include dense wavelength division multiplexing systems requiring tightly spaced wavelength subranges for each of multiple channels. High wavelength stability against temperature and humidity changes, etc., can be achieved.

Abstract: An interference filter (10, 30, 50, 70, 90, 110, 130, 150, or 190) filters selected wavelengths by dividing an input beam into two or more intermediate beams having different optical path lengths and by recombining the intermediate beams into an output beam that is modified by interference between the intermediate beams. An optical path length difference generator (20, 40, 60, 80, 100, 120, 140, 160, or 200) varies the optical path lengths of the intermediate beams by changing the physical lengths of their paths or the refractive indices of the mediums in which they are conveyed. The optical path length generator (20) of one exemplary embodiment (10) includes a spacer plate (20) that is divided into elements (22 and 24) having different refractive indices for varying the optical path lengths of the intermediate beams.

Abstract: The present invention relates to a multi-wavelength multi-stage fiber amplifier exhibiting high power output with a flat balanced gain spectrum. The input stage exhibits a given passive loss and a flattened gain spectrum. The output stage exhibits a passive loss that is lower than the given passive loss and a gain spectrum that is less flat than the gain spectrum of the input stage. In a system utilizing erbium-based gain fibers, the input stage gain fiber can contain an amount of alumina sufficient to provide the desired gain spectrum flatness, while the output stage gain fiber has an alumina concentration sufficiently low to render that stage essentially lossless.

Abstract: An optical fiber switch in accordance with the present invention includes an optical fiber, a gate signal generating system, and a coupling system. The optical fiber has a birefringence between 10.sup.-5 and 10.sup.-6 and an effective area of at least 40 square microns. The generating system generates a gating signal having a power level which induces non-linear birefringence in the optical fiber causing an input signal in the optical fiber to switch polarization modes. The coupling system couples the input signal and the gating signal into the optical fiber. The optical fiber in the optical switch is designed to minimize non-linear effects which would degrade an input signal in the optical fiber switch. In particular, the optical fiber switch is designed to reduce the amount of power required by the gating signal to switch the input signal in the optical fiber, thus reducing the possibility of the fiber fuse and the generation of higher order solitons through Raman effects.

Abstract: A transparent class ceramic composition includes an oxide component, a rare earth component, a halide component, and a substantially pure rare earth-halide (e.g., REF.sub.3) crystal component. A method for making a transparent oxyfluoride glass includes preparing an oxyfluoride glass containing rare earth ions by a conventional melting method and subjecting the glass to a heat treatment thereby precipitating fluoride fine crystals containing a large amount of rare earth ions.

Abstract: The present invention relates to a transparent glass-ceramic article which includes a glass matrix and a crystalline phase of apatite crystals in the glass matrix. The present invention further relates to a method of producing the transparent glass-ceramic article.

Abstract: A fiber optic system in accordance with the present invention includes an optical fiber, a coupling device, and a system for generating a pump signal. The optical fiber has a birefringence which preserves polarization and has a first polarization mode which is substantially perpendicular to a second polarization mode. The coupling device couples an input signal with an input wavelength into the optical fiber so that the input signal propagates in the first polarization mode in the optical fiber. The system for generating a pump signal generates a pump signal with a pump wavelength which is within a range of 50 nanometers (nm) to 300 nm less than the input wavelength and which has a first amount of pump power which is enough power to switch the input signal, but not enough to create higher order solitons. The coupling device also couples the pump signal into the optical fiber so that the pump signal propagates in the first polarization mode in the optical fiber.

Abstract: A device for adding and/or dropping a signal to a transmission line. First and second optical circulators are connected by at least one switchable grating reflector, whereby a grating reflector can be switched into or out of the connecting path between the two circulators. A plurality of optical signals, each centered about a different wavelength, is coupled to a first port of the first circulator; these signals appear at the second port thereof. If a grating reflector capable of reflecting .lambda..sub.i is switched into the circuit, the signal centered about .lambda..sub.i propagates from the second port of the first circulator and reflects from the grating reflector back into the second port and out of the third port. The remainder of the input signals that are not reflected by grating reflectors propagate into the first port and from the second port of the second circulator as an output thereof. Also, a signal at wavelength .lambda..sub.

Abstract: A fiber optic device for use in fiber optic transmission systems and components thereof includes a pass-through fiber and one or more lengths of circulating fiber connected to the pass-through fiber by respective optical switches for selectively routing an optical signal through the circulating fiber lengths as it propagates along the pass-through fiber. The circulating fiber lengths are either dispersion compensating fibers or fibers doped with a substance that will amplify or absorb the optical signal in the respective presence or absence of a pump signal. The invention thus allows various amounts of dispersion or gain (absorption) to be selectively switched into or out of use depending upon requirements at the time. For example, an amplifying component could serve as a pre- or power- or in-line amplifier device depending on the lesser or greater amount of gain fiber elected by switching.

Abstract: An exercise apparatus includes a base and a bench supported above the base by a support structure interconnecting the base and a center section of the bench. The bench includes one wing section attached to a side of the center section in a manner that allows fixing the one wing section in a range of discreet positions from about 15 degrees above to 90 degrees below a horizontal plane of the center section, and another wing section attached to an opposite side of the center section in a similar manner. Each wing section has a lengthwise slotted opening located between an edge and a longitudinal centerline of the wing section. The apparatus is further equipped with a set of variable resistances connected to a set of handles by a set of cords that run over a set of fixed and movable guides. An end of each cord passes through a slot in each wing section.

Abstract: A core layer of a planar gradient-index waveguide lens is formed from a longitudinal section of a graded-index blank. The longitudinal section is mounted on a substrate that provides support for subsequent operations on the longitudinal section and that also functions as a cladding layer of the waveguide lens. The longitudinal section can be machined or redrawn in a furnace together with the substrate to a final thickness dimension.

Abstract: A structure for use in forming an optical component and a method of making such a component is described. The structure comprises a non-waveguiding body of optical material having a concentration of a photorefractive-sensitive component in the body such that upon irradiation of a part of the body by a beam of actinic radiation, the refractive index of the irradiated part is increased. The method of making the optical component comprises providing a non-waveguiding body of optical material; providing a concentration of a photorefractive-sensitive component in the body; contacting the non-waveguiding body of optical material with an atmosphere comprising one of hydrogen, deuterium and mixtures thereof; and exposing a part of the non-waveguiding body of optical material to actinic radiation such that the refractive index of the exposed part is increased. Such a structure and method can be used to form symmetrical planar waveguides, optical fiber waveguides and other optical components such as gratings.

Abstract: An optical multiplexing device demultiplexes collimated light from a fiber-optic source into separate individual wavelength sub-ranges or channels, and/or multiplexes separate channels to a common fiber-optic waveguide or other destination. An optical block defines an optical gap between two parallel surfaces having an optical port on a first such parallel surface for passing the multi-channel collimated light into the optical gap. A channel port and at least one other reflective element, e.g., multiple channel ports arrayed in spaced relation to each other, are secured to the optical block at the parallel surfaces, providing an unobstructed, epoxy-free multi-point light path within the optical gap. At each channel port an interference filter secured to the optical block spans the optical gap. Each filter transmits a wavelength sub-range of the multi-channel collimated light passed by the optical port, and reflects other wavelengths.

Abstract: A variable period amplitude grating mask for use in making a long period Bragg grating is realized by a helically coiled spring. Stretching or compressing the spring changes the periodicity of the mask. A photosensitive optical waveguide, planar or fiber, is positioned within the spring coils along the major axis of the spring. Actinic radiation is incident on the masked waveguide, and induces an index perturbation in the waveguide having the periodicity of the mask. Different spring coil sizes and/or orientation of the waveguide with respect to the mask provide linear and nonlinear (chirped) grating periods. A device and method are described.

Abstract: A method and apparatus for producing optical films on substrates having extremely high packing densities of the same quality as those films produced by ion beam sputtering including a vacuum chamber with a conventional magnetron sputtering system and unusually high speed vacuum pump means. The low pressure of inert gas created by said high speed vacuum pump means being in the range of 5.times.10.sup.-5 Torr to 1.5.times.10.sup.-4 Torr and the magnetron sputtering system being at least 16" from said substrates. A gas manifold around the magnetron and target material confines the inert working gas in the vicinity of the magnetron and as the gas diffuses and expands into the chamber the high speed vacuum pump means removes the expanded gas from the chamber at a high speed. An ion gun directs ionized reactant gas toward the substrates which has the effect of improving film stoichometry as well as reducing reactant gas at the magnetron.

Abstract: A method for forming a substantially flat planar lightwave optical circuit which has a substantially flat planar silica substrate and a sintered glassy lightguiding layer over the silica substrate. The structure is given a post treatment at an elevated temperature for a time sufficient to flatten said structure and overcome any distortion caused by the difference in the coefficient of thermal expansion of the substrate and any glassy layers formed over the substrate. Alternatively, the silica substrate may be heated and presagged to a predetermined degree to compensate for distortion or warpage which will occur in later processing.

Abstract: An improved four-port dichroic WDM, for use in a multiwavelength, bi-directional optical amplifier, having a dichroic filter for substantially reflecting a first wavelength band input to the WDM to an output of the WDM for the first wavelength band and for substantially transmitting a second wavelength band input to the WDM to an output of the WDM for the second wavelength band, in which some of a first 3 dB wavelength in the first wavelength band is transmitted by the filter and some of a second 3 dB wavelength in the second wavelength band is reflected by the filter, includes another dichroic filter having a filter function different than the filter function of the WDM filter providing an insertion loss for the first or the second 3 dB wavelengths sufficient to reflect and transmit, respectively, substantially all of the first and second 3 dB wavelengths.

Abstract: A low weight, achromatic, athermal, long wave infrared objective lens with one element having a positive optical power and the other element having a negative optical power but with a higher thermo-optic coefficient than the thermo-optic coefficient of the first element. A diffractive color correcting optical surface is generated on one surface of one of the elements and aspheric surfaces may be included for further performance gains.

Abstract: Methods for determining optical properties of an optical waveguide fiber using an optical time domain reflectometer (OTDR) are provided. The methods involve the removal of noise from an OTDR trace (signal) by fitting the noise component of the signal and then subtracting the fitted noise from the original signal to produce a noise-reduced signal. Optical properties are more readily determined from the noise-reduced signal than from the original signal. In particular, the noise-reduced signal can be used to determine axial optical properties of long fibers, e.g., fibers having a length of 50 kilometers or more.