Georgia Tech Research Corporation

Verifiber Technologies, Inc.

Other

Verifier Technologies, Inc.

Emmanuel Anemogiannis

Thomas K Gaylord

Elias N Glytsis

Donald D Davis

Leo J Thompson

Gregory Douglas VanWiggeren

Gregory D Van Wiggeren

The present invention relates to a type of optical fiber grating having an azimuthal refractive-index perturbation. The optical fiber includes a fiber grating that has a plurality of grating elements formed therein. At least one of the grating elements has a spatially varying index of refraction that varies azimuthally about the centerline of the optical fiber. The fiber grating acts as a band-stop optical spectral filter. In addition, since fiber-cladding modes are weakly-guided modes, their power can be easily dissipated by scattering, bending, stretching, and/or rotating the optical fiber. Multiple configurations of these gratings within an optical fiber are given. Methodologies are given for the fabrication of these gratings. Devices are presented which can dynamically attenuate, tune, switch, or modulate the wavelength spectral characteristics of an optical signal.

Optical fiber gratings with azimuthal refractive index perturbation

The present invention relates to a type of optical fiber grating having an azimuthal refractive-index perturbation. The optical fiber includes a fiber grating that has a plurality of grating elements formed therein. At least one of the grating elements has a spatially varying index of refraction that varies azimuthally about the centerline of the optical fiber. The fiber grating acts as a band-stop optical spectral filter. In addition, since fiber-cladding modes are weakly-guided modes, their power can be easily dissipated by scattering, bending, stretching, and/or rotating the optical fiber. Multiple configurations of these gratings within an optical fiber are given. Devices are presented which can dynamically attenuate, tune, switch, or modulate the wavelength spectral characteristics of an optical signal.

Optical fiber gratings with azimuthal refractive index perturbation and devices for tuning, attenuating, switching, and modulating optical signals

Optical fiber gratings with azimuthal refractive index perturbation, method of fabrication, and devices for tuning, attenuating, switching, and modulating optical signals

An apparatus for measuring environmental parameters comprising an optical fiber-based sensor having thermally-induced diffraction gratings therein which are stable at very high temperatures for many hours. The diffraction gratings are, preferably, formed in an optical fiber by exposure to light from an infrared laser and do not degrade at high temperatures. A system for measuring an environmental parameter includes an optical fiber-based sensor, a light source, and a detector. According to a method of measuring an environmental parameter, the optical fiber-based sensor is positioned within a high-temperature environment having a parameter desired for measurement. The light source directs light into the optical fiber-based sensor. The detector measures the differential diffraction of the light output from the optical fiber-based sensor and determines a value of the environmental parameter based, at least in part, upon a known correlation between the differential diffraction and the environmental parameter.

Very-high-temperature-stable fiber grating-based sensor

A plurality of optical communications systems including a SPW modulator are described. The communications systems include an optical transmitter coupled to an optical fiber communications link which carries a optically modulated information signal to an optical receiver. The laser transmitter includes a laser light source which is optically coupled to a SPW modulator which has been particularly adapted for broadband communications by selecting its transfer characteristic and modulation structure. A broadband signal containing a plurality of information channels, for example CATV channels, is applied to it modulator electrodes. The modulation signal varies the power coupling between the guided laser light source signal and a SPW in the modulator. The result is an intensity modulated optical signal that is output to the optical fiber for transmission to the optical receiver of the system. Alternatively, the communications system includes a high power laser coupled to an optical splitter to divide its output power in two or more optical source outputs. Each optical source output is then used to drive an associated SPW modulator. Each of the modulators receives a broadband signal with which to modulate its optical source. After modulation, the modulated lightwave from a modulator is coupled to a corresponding optical fiber for carriage to an optical receiver. In this manner, several broadband information signals can be communicated over the system using only one laser source. A net benefit from using one higher power laser, rather than several lower power ones, is one of cost, purity and similarity of the several signals. This configuration is enhanced by the lower loss and higher linearity of the SPW modulators. Further, several WDM embodiments including those having serially cascaded SPW modulators are provided. The transfer characteristic of the SPW modulators are tailored to either be more efficient for an analog or a digital modulation signal by adding or subtracting grating effects.

Optical surface plasmon-wave communications systems

Optical plasmon-wave attenuator and modulator structures for controlling the amount of coupling between an guided optical signal and a surface plasmon wave. Optical power coupled to the plasmon wave mode is dissipated in varying amounts producing an intensity modulation effect on the optical signal. For electrical modulation, an additional dielectric (or polymer) layer with variable refractive index in optical contact with a metal layer supporting at least one plasmon wave mode is used to perturb or vary the propagation constant of plasmon wave. Propagation constant variation results in the power coupling variation between the surface plasmon wave and the optical wave. The refractive index variation of the dielectric (or polymer) layer can be accomplished via an electro-optic traveling-wave, a lump-element, or any other integrated optics modulator configuration situated to affect the layer, thereby permitting data rates into tens of GHz. Because of the extremely small interaction lengths needed, the optical plasmon-wave modulator is a very compact device which can be implemented on the top of a fiber or as an integrated optical planar structure.

Optical plasmon-wave structures

A method and apparatus for detecting a fault, such as a break or crack in a fiber optic cable. A test device transmits into a first end of fiber bundle under test a first pulse of optical energy. The time duration and/or intensity of the pulse propagating through the fiber after being reflected back through the fiber are determined and stored in memory. At a later point in time this step is repeated with a second pulse. If the propagation time and/or intensity of the second pulse varies by greater than a predetermined amount from that of the first pulse an alarm condition is indicated. From the propagation time of the second pulse a length is calculated and provided to the user. This length corresponds to the location of the fault.

Apparatus and method for detecting optical fiber fault location

A method and apparatus for distinguishing between fiber types having different dispersion characteristics and arbitrary lengths is disclosed. An optical pulse having a predetermined wavelength and predetermined time width is propagated through the fiber and then detected. The optical pulse after being fed through the fiber is measured at different wavelengths along with the length of the fiber. If the measured pulse is within a predetermined amount at the determined length, then fiber under test corresponds to a type having a first dispersion characteristic. If it is determined that the measured pulse is within a second amount, then the fiber under test corresponds to a type having a second dispersion characteristic. Alternately one or more optical pulses of arbitrary width each having different wavelengths after being propagated through the fiber under test is fed through a plurality of filters and detected. The wavelength of the pulse of the smallest time duration is detected and a corresponding dispersion characteristic is then indicated.

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Atlanta, GA, United States of America

Emmanuel Anemogiannis