Abstract: The present invention relates to a sensor interrogation system which comprises an optical fiber, at least one sensor containing first and second fiber lasers attached to the optical fiber with the first fiber laser being located spectrally at a first wavelength and the second fiber laser being located spectrally at a second wavelength different from the first wavelength, a pump laser for causing light to travel down the optical fiber so as to cause each of the fiber lasers to lase at its distinct wavelength and generate a distinct laser signal representative of the distinct wavelength, at least one filter for receiving the laser signals generated by the first and second lasers and for transmitting the laser signals from the first and second lasers within a wavelength band, and first and second scanning Fabry-Perot spectrum analyzers for receiving the laser signals for determining the wavelength difference between said fiber lasers.

Abstract: The subject-matter of the present invention is a wavelength-coded fiber Bragg grating pressure sensor 1 which is suitable, in particular, for use in the case of high pressures and temperatures in oil drill holes. The sensor principle according to the invention is based on the fact that the hydrostatic pressure of a liquid or gaseous medium 11 is converted with the aid of a transducer 1 into a longitudinal fiber elongation or fiber compression. The transducer 1 comprises a measuring or pressure cylinder 7a which exchanges pressure with the medium 11, and a reference cylinder 7b which is shielded from the medium 11 or oppositely pressure-loaded. Temperature-compensated transducers 1 with a temperature-independent Bragg wavelength &lgr;B can be realized by introducing a suitable temperature dependence of the mechanical prestressing of the pressure sensor fiber 3 by selecting the materials, lengths and arrangements of the fiber holder supports 5a, 5b.

Abstract: An optical amplifying glass fiber comprising a core glass and a clad glass, wherein a relation of: 0.0005≦(n1−n2)/n1≦0.1 where n1 and n2 are refractive indices of the core glass and the clad glass, respectively, is satisfied, the fiber has a length of at most 25 cm, the core glass contains Er, and the wavelength width wherein a gain is obtainable with light having a wavelength of from 1.50 to 1.59 &mgr;m, is at least 30 nm.

Abstract: The present invention provides an optical signal add/drop apparatus comprising: an optical signal multiplexing/demultiplexing portion comprising a plurality of 2×2 channel unit devices which are arranged in a straight line and having first and second dual-core ferrules having two optical fibers disposed to be symmetrical to each other at an identical distance from an optical axis for transmitting optical signals, a wavelength division filter disposed between first and second lenses for selectively transmitting or reflecting only the optical signals having specific wavelengths, first and second grin lenses for collimating or focusing the optical signal transmitted or reflected from said wavelength division filter and then transmitting the signal to the first and second dual-core optical fibers; and a switch module having unit 2×2 switches connected to two optical fibers of the second dual-core ferrule of each of the unit devices of said optical signal multiplexing/demultiplexing portion; wherein th

Abstract: This invention provides a novel wavelength-separating-routing (WSR) apparatus that uses a diffraction grating to separate a multi-wavelength optical signal by wavelength into multiple spectral channels, which are then focused onto an array of corresponding channel micromirrors. The channel micromirrors are individually controllable and continuously pivotable to reflect the spectral channels into multiple output ports. As such, the inventive WSR apparatus is capable of routing the spectral channels on a channel-by-channel basis and coupling any spectral channel into any one of the output ports. The WSR apparatus of the present invention may be further equipped with servo-control and spectral power-management capabilities, thereby maintaining the coupling efficiencies of the spectral channels into the output ports at desired values.

Abstract: A system detects potentially dangerous conditions, prevents damage to optical components, and prevents humans from being physically harmed by stray pumping light. Optical systems employing distributed amplification such as Raman amplification utilize pumps having high output powers. These high output powers create dangerously high power densities in the optical fiber. If a connection is imperfect a hot spot may develop and the connection damaged by the pumping light. Fiber damage, disconnections and component degradations or failures may also permit the pumping light to escape the intended path and cause physical harm to humans as well as equipment. Pumping light backreflections caused by such imperfect connections, degraded/failed components, and fiber damage are detected. A controller compares the backreflection amount against a threshold to determine whether a precautionary measure should be taken such as shutting down the pump, decreasing pump power to a safe level or setting a maintenance flag.

Abstract: To protect a waveguide or cable in an installation channel, a protective profile is inserted into the channel and has a substantially U-shaped cross-section when installed. To install this in the channel, an apparatus having a drum with a profile wound thereon has the profile unwound and guided by guide rolls to a press roll, which presses the profile into the channel to the desired depth. The profile can have a center portion provided with embedded reinforcing elements or even optical or electrical leads.

Abstract: A planar waveguide integrated optic switch suitable for use in optical cross-connect applications. A narrow trench in the planar waveguide core layer is filled with a liquid crystal material possessing positive birefringence. When held at a temperature a few degrees above the clearing point, the liquids crystal's isotropic refractive index is matched to that of the core layer allowing nearly complete optical transmission through the switch. When held at a temperature a few degrees below the clearing point, the liquid crystal's ordinary refractive index is lower than that of the core layer and both polarizations of the incident optical radiation are totally reflected from the trench. When coupled with planar waveguide beam expanding and refocusing elements, arrays of the switches can be used to form an optical cross-connect capable of fully interconnecting linear arrays of single- or multi-mode optical fibers with very low optical loss.

Abstract: Disclosed is a dispersion compensating optical fiber that includes a core surrounded by a cladding layer of refractive index &Dgr;c. The core includes at least three radially adjacent regions, a central core region having &Dgr;1, a moat region having a refractive index &Dgr;2 and an annular ring region having a refractive index &Dgr;3, such that &Dgr;1>&Dgr;3>&Dgr;c>&Dgr;2. The fiber exhibits a dispersion at 1550 which is less than −30 ps/nm/km, and a &kgr; value obtained by dividing the dispersion value by the dispersion slope which is between 40 and 100.

Abstract: An optical switch has at least a light transmission portion, an optical path-changing portion, and an actuator portion. The light transmission portion has a light reflecting plane on at least one part of a surface facing the optical path-changing portion to totally reflect light; and light transmission channels having optical wave guiding bodies and being provided in at least three directions with the light reflecting plane as a starting point. The optical path-changing portion is provided in proximity to the light reflecting plane of the light transmission portion in a movable condition and has a light introduction member made of a translucent material and a light reflection member for totally reflecting light. The actuator portion has a mechanism that is displaced by external signals and transmits the displacement to the optical path-changing portion.

Abstract: A wavelength demultiplexer is provided whose overall length in a first propagation direction is short, whose production efficiency is high, and whose emission loss is smaller than that of conventional configurations. At the first end face V1, the first boundary line F1 is closer to the second edge H2 than the first edge H1 by the distance “b” (b>0). At the first end face V1, the second boundary line F2 is closer to the first edge H1 than the second edge H2 by the distance “b”. At the third end face V3, the fourth boundary line F4 is closer to the fourth edge H4 than the third edge H3 by the distance “a” (a>0). At the fourth end face V4, the sixth boundary line F6 is closer to the third edge H3 than the fourth edge H4 by the distance “a”.

Abstract: An integrated optical device has two waveguide layers that are patterned to provide 2-dimensional interconnected networks of waveguides. A filter layer between the two waveguide layers is made by sputter deposition of thin films with alternating indexes of refraction. Light traveling vertically through the filter layer experiences an interferometric effect. A deflecting bump is formed in the plane of the lower waveguide layer. The bump is isotropicly etched, undercutting a photo-mask over the bump, producing a rounded, concave profile to the bump. High-index material is deposited over the bump and patterned to form a waveguide that has light deflected by the bump upward. The filter is formed over the bump to receive the deflected light. The filter reflects some light back down to the bump to another waveguide in the first layer. Light transmitted vertically up through the filter is bent to the horizontal plane of the upper waveguide layer.

Abstract: An optical switching device routes optical signals, completely within optical media, from an arbitrary number of N input optical fibers to a different set of M output optical fibers. The switching device uses a thermal microcantilever bimorph optical switch to redirect optical radiation emitted by a laser light source, or from the end of an optical fiber, to an input end of another optical fiber. The modulated optical radiation containing signals from the input fiber optic bundle or laser light source is collimated into parallel beams and projected in free space across the tops of an array of the microcantilever bimorph optical switches. When selected, a particular switch is activated, pops up, intercepts, and reflects the optical radiation down into a cavity and then into a short section of parallel waveguide. The radiation is directed into a transverse waveguide and then to an output optical coupler. This radiation is then coupled into the selected output optical fiber.

Abstract: A variable chirp optical modulator is provided in which an optical waveguide is split for part of its length into first and second waveguide arms. Electrode pairs are utilized to provide modulating electric fields in a portion of the first and second waveguide arms. The optical lengths of the portions of the first and second waveguide arms that are subject to the modulating electric fields are different and are selected to provide a predetermined level of chirp. By controlling the optical power split from the optical waveguide to the first and second arms, the chirp is varied from the predetermined level.

Abstract: An optical fiber tap for transferring optical energy out of an optical fiber having an optical fiber with a short tapered section for coupling optical energy into cladding modes, and a surrounding glass body fused to the optical fiber with the glass body having a polished surface positioned at an angle so as to reflect, by total internal reflection, cladding mode energy away from the optical fiber. An additional glass encapsulating tube is fused to and hermetically seals the glass body and tapered fiber section. For use in an optical power monitor, the optical fiber tap is integrated into a standard electronic package containing a photodiode to convert the tapped-out optical energy into an electrical signal representing the optical energy carried by the optical fiber.

Abstract: A Raman-amplified optical transmission system 80 includes a source of optical transmission signals having a system wavelength, &lgr;s, that are connected to one end of the of a first optical fiber 50-1 having a large effective area, i.e., Aeff≧70 &mgr;m2. The other end of the first optical fiber is connected to a second optical fiber 50-2 having a small effective area, i.e., Aeff≦60 &mgr;m2. Preferably, the first and second optical fibers have opposite dispersion signs. A wavelength-division multiplexer 87, for example, couples optical transmission signals &lgr;1 . . . &lgr;n, from an optical pump 88 to the second optical fiber that cause it to exhibit stimulated Raman scattering, which provides amplification of the optical transmission signals. Preferably, the optical pump signals propagate along the second optical fiber in a direction that is opposite the direction of the optical transmission signals. Exemplary cables 500, 600 are disclosed that include both large and small-effective-area fibers.

Abstract: An optical coupler reduces differential mode delay in a fiber by reducing an amount of light incident on the fiber in a region in which the refractive index is not well controlled. This region of the fiber is typically in the center of the fiber. The optical coupler directs light away from the this region and/or provides a high angle of incidence to any light on this region. A diffuser may be used to reduce sensitivity of the coupler to any fluctutations in the output of the light source. The optical coupler does not need to be offset from the center of the multi-mode coupler. A phase function of an azimuthal mode of the fiber may be imposed on the light beam so that a substantial null on axis is maintained even after propogation of the light beam beyond the depth of focus of the coupler. A diffractive element generating a beam which propogates in a spiral fashion along an axis allows the shape of the beam to be maintained for longer than a depth of focus of the diffractive element.

Abstract: A symmetric optical switch for selectively switching wavelength channels between four optical inputs. The symmetric optical switch includes two dispersive elements receiving optical inputs from respective optical fibers where the optical inputs are dispersed into a plurality of wavelength-separated input channels. The symmetric optical switch also includes a plurality of circulators disposed on each optical fiber and a switching array mechanism that receives the plurality of wavelength-separated input channels from each of the dispersive elements. The shutter array simultaneously switches one or more pairs of the wavelength-separated input channels between four optical inputs. Each circulator that is disposed on the associated optical fiber operates with the shutter array to form an eight port device so as to independently switch wavelength channels.

Abstract: A variable chirp optical modulator is provided. An optical waveguide is split for part of its length into first and second waveguide arms. Electrode pairs are positioned to be proximate a first portion of corresponding waveguide arms. The lengths of each of the electrodes are different and are selected to provide a predetermined level of chirp.

Abstract: A multilayer optical fiber coupler for coupling optical radiation between an optical device and an optical fiber, including a first layer that has a fiber socket formed by photolithographic masking and etching to extend through said first layer, and a second layer bonded to the first layer. The first layer may comprise substantially single-crystal silicon. An optical fiber is inserted into the fiber socket to align the optical fiber precisely within the fiber socket. In one embodiment the optical fiber is a single mode fiber, and an optical focusing element formed on the second layer is aligned with the core of the single mode fiber. The second layer may comprise glass having an index of refraction that approximately matches the index of the optical fiber, and an optical epoxy is used to affix the optical fiber into the fiber socket and fill the gaps between the end face of the fiber and the second layer.