Abstract: A fluid diffusion resistant tube-encased fiber grating pressure sensor includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within a sensing element, such as a glass capillary shell 20. A fluid blocking coating 30 is disposed on the outside surface of the capillary shell to prevent the diffusion of fluids, such as water molecules from diffusing into the shell. The fluid diffusion resistant fiber optic sensor reduces errors caused by the diffusion of water into the shell when the sensor is exposed to harsh conditions.

Abstract: A tunable optical filter has a large diameter cane waveguide with “side-holes” in the cane cross-section that reduce the force required to compress the large diameter optical waveguide without overly compromising the buckling strength thereof. The large diameter optical waveguide has a cross-section of at least about 0.3 millimeters, including at least one inner core, a Bragg grating arranged therein, a cladding surrounding the inner core, and a structural configuration for providing a reduced bulk modulus of compressibility and maintaining the anti-buckling strength of the large diameter optical waveguide. The structural configuration reduces the cross-sectional area of the large diameter optical waveguide. These side holes reduce the amount of glass that needs to be compressed, but retains the large diameter.

Abstract: The invention provides a pressure transducer having a cane waveguide geometry with “side-holes” in the cane cross-section that reduce the force required to compress the large diameter optical waveguide. The large diameter optical waveguide has a cross-section of at least about 0.3 millimeters, at least one inner core, a Bragg grating arranged therein, a cladding surrounding the inner core, and a structural configuration for providing a reduced bulk modulus of compressibility and maintaining the anti-buckling strength of the large diameter optical waveguide. The structural configuration reduces the cross-sectional area of the large diameter optical waveguide. These side holes reduce the amount of glass that needs to be compressed, but retains the large diameter.

Abstract: A method for erasing some or all of at least some of the grating elements of a grating inscribed in an optical waveguide such as an optical fiber or a cane structure (a more rigid optical waveguide), or, more generally, for selectively altering the index of refraction of a span of an optical waveguide, and products provided by the method. A temperature profile suitable for achieving a predetermined desired apodization (shaping of the grating strength) is determined, and then a focused laser beam, from for example a CO2 laser, is directed to a target site on the optical waveguide selected as a suitable point from which to direct the laser beam and so introduce heat into the optical waveguide. The laser beam is held on the target site only so long as is necessary to create at least a portion of the temperature profile.

Abstract: A reconfigurable multifunctional optical device has an optical arrangement for receiving an optical signal, each having optical bands or channels, and a spatial light modulator for reflecting the at least one optical signal provided thereon. The optical arrangement features a free optics configuration with a light dispersion element for spreading each optical signal into one or more respective optical bands or channels for performing separate optical functions on each optical signal. The spatial light modulator includes a micro-mirror device with an array of micro-mirrors, and the respective optical bands or channels reflect off respective micro-mirrors. The free optics configuration includes a common set of optical components for performing each separate optical function on each optical signal. The separate optical functions reflect off separate non-overlapping areas on the spatial light modulator. The separate optical functions include optical switching, conditioning or monitoring functions.

Abstract: A fiber Bragg grating based sensor is disclosed. The sensor comprises an optical waveguide having a core and a cladding. The core comprises a pressure sensor such as a fiber Bragg grating. In one embodiment, a support is affixed around the cladding which has two first portions each having a first diameter. The pressure sensor is located at a second portion of the support positioned between the two first portions which has a second smaller diameter, thus giving the sensor a “dog bone” shape. In another embodiment, the dog bone shape is imparted by positioning the pressure sensor at a portion of a waveguide having a reduced cladding diameter.

Abstract: An apparatus serving as a Fabry-Perot optical device, including: a large-diameter elongated optical waveguide having a core and having an air gap region disposed along the longitudinal axis of the waveguide, and with the air gap region enclosed by end faces substantially perpendicular to the longitudinal axis of the waveguide, the waveguide also having a cavity delimited on at least one side by an endface of the air gap, wherein the endface is at least partially reflective. From another perspective, the invention provides an apparatus including: a force-applying assembly, responsive to a control signal containing information about a selected resonated wavelength or a selected filtered wavelength derived from an optical signal, for providing a force; and a Fabry-Perot optical structure, responsive to the force, and further responsive to the optical signal, for providing a Fabry-Perot optical structure signal either with the selected resonated wavelength or without the selected filtered wavelength.

Abstract: A compression-tuned fiber Bragg grating based reconfigurable wavelength add/drop module has a compression force assembly and an all-glass Bragg grating compression unit having gratings spaced along an axis of compression. The compression force assembly responds to a control electronics signal containing information about a selected wavelength of a channel to be added to or dropped from an optical traffic signal, for providing a compression force applied along the axis of compression. The compression unit responds to the optical traffic signal and the compression force, for providing an all-glass Bragg grating compression unit optical signal having the selected wavelength of the channel to be added to or dropped from the optical traffic signal. The compression unit optical signal may include either the traffic with an added reflected channel(s), or a dropped reflected channel(s).

Abstract: A reconfigurable optical blocking filter deletes a desired optical channel(s) from an optical WDM input signal, and includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that tilt between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimators, diffraction grating, and Fourier lens, collectively collimate, separate and focus the optical input channels onto the array of micro-mirrors. The optical channel is focused on the micro-mirrors onto a plurality of micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels. To delete an input channel of the optical input signal, micro-mirrors associated with each desired input channel are tilted to reflect the desired input channel away from the return path.

Abstract: A fluid diffusion resistant tube-encased fiber grating pressure sensor includes an optical fiber 10 having a Bragg grating 12 impressed therein which is encased within a sensing element, such as a glass capillary shell 20. A fluid blocking coating 30 is disposed on the outside surface of the capillary shell to prevent the diffusion of fluids, such as water molecules from diffusing into the shell. The fluid diffusion resistant fiber optic sensor reduces errors caused by the diffusion of water into the shell when the sensor is exposed to harsh conditions.

Abstract: A chromatic dispersion compensation device selectively delays a respective portion of spectral sections of each respective optical channel of an optical WDM input signal to compensate each optical channel for dispersion compensation, and includes a spatial light modulator having a micromirror device with a two-dimensional array of micromirrors. The micromirrors tilt or flip between first and second positions in a “digital” fashion in response to a control signal provided by a controller in accordance with a switching algorithm and an input command. A collimator, diffraction gratings, and Fourier lens collectively collimate, disperse and focus the optical input channels onto the array of micromirrors. Each optical channel is focused onto micromirrors of the micromirror device, which effectively pixelates the optical channels.

Abstract: A large diameter waveguide is provided having a diameter of at least about 0.3 millimeters, and an outer cladding with an inner core with a blazed grating included therein, which is written into the inner core at an oblique angle relative to a longitudinal axis of the inner core either for attenuating optical light traveling in the optical waveguide, or for reflecting optical light to or from the optical waveguide. The blazed grating has an optical parameter that changes in response to an application of a compressive force on the optical waveguide. The outer cladding may have the blazed grating written therein. The blazed grating has concatenated periodic or aperiodic gratings. The optical waveguide may be shaped like a dogbone structure having wider outer sections and a narrower central section inbetween. The blazed grating is written in the narrower central section of the dogbone structure.

Abstract: A temperature compensated optical device includes a compression-tuned glass element 10 having a Bragg grating 12 therein, a compensating material spacer 26 and an end cap 28 all held within an outer shell 30. The element 10, end cap 28 and shell 30 are made of a material having a low coefficient of thermal expansion (CTE), e.g., silica, quartz, etc. and the spacer 26 is made of a material having a higher CTE, e.g., metal, Pyrex®, ceramic, etc. The material and length L5 of the spacer 26 is selected to offset the upward grating wavelength shift due to temperature. As temperature rises, the spacer 26 expands faster than the silica structure causing a compressive strain to be exerted on the element 10, which shifts the wavelength of the grating 12 down to balance the intrinsic temperature induces wavelength shift up. As a result, the grating 12 wavelength is substantially unchanged over a wide temperature range.

Abstract: The present invention provides a new and unique method, sensor, and apparatus for performing a seismic survey of an earth formation in relation to a borehole. The method includes arranging at least one strain seismic sensor in conjunction with a borehole structure, and mechanically coupling the borehole structure to the borehole to allow seismic data to be accurately transferred to the sensor. The sensor is preferably a fiber optic sensor, including a Fiber Bragg Grating which may be coupled to a relevant borehole structure in a number of ways.

Abstract: A compression-tuned Bragg grating-based laser 800 includes a pair of optical grating elements 802,804 wherein at least one of the grating elements is tunable by a compression device 812,814. The grating elements may include either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating element 600 having a core and a wide cladding. The tunable grating element(s) 802,804 are axially compressed, which causes a shift in the reflection wavelength of the gratings 807,809 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. A gain element, such as Erbium doped fiber, is optical disposed between the grating elements to provide the lasing cavity.

Abstract: A tunable optical filter filters is provided that has a pair of tunable Bragg grating units optically coupled to respective ports of a 4-port circulator for filtering a selected wavelength band or channel of light from a DWDM input light. Each grating unit includes an array of Bragg gratings written or embedded within a respective tunable optical element to provide a tunable optical filter that functions over a wide spectral range greater than the tunable range of each grating element. The reflection wavelengths of the array of gratings of each respective grating element is spaced at a predetermined spacing, such that when a pair of complementary gratings of the grating elements are aligned, the other complementary gratings are misaligned. Both of the optical elements may be tuned to selectively align each complementary grating over each corresponding spectral range.

Abstract: A tunable Raman laser and amplifier include a pair of tunable optical units optically connected by a length of optical fiber having an associated Raman gain. The tunable optical units tune respective optical waveguides, each of which includes an inner core disposed within an outer cladding. A plurality of Bragg gratings is written in each core of the waveguides. The reflection wavelengths of each Bragg grating of the input waveguide is the same as the reflection wavelength of a matched grating of the output waveguide, to thereby form a plurality of cascaded resonance cavities. Each resonance cavity has a reflecting wavelength equal to the center wavelength of successive Stokes orders associated with optical fiber. The Bragg gratings of each waveguide are written into a corresponding stepped region ground into the outer cladding of the waveguides. The tuning (e.g.

Abstract: A method and corresponding system for measuring the speed of sound in a fluid contained within an elongated body, the sound transversing the elongated body substantially along a direction aligned with the longest axis of the elongated body, the method including the steps of: providing at predetermined locations an array of at least two sensors distributed along the elongated body, each sensor for discerning and signaling spatio-temporally sampled data including information indicating the pressure of the fluid at the position of the sensor; acquiring the spatio-temporally sampled data from each sensor at each of a number of instants of time; constructing a plot derivable from a plot, using a technique selected from the group consisting of spectral-based algorithms; identifying in the plot a spectral ridge, and determining the slope of the spectral ridge; and determining the speed of sound assuming a relation between the speed of sound and the slope of the spectral ridge.

Abstract: A reconfigurable optical add/drop multiplexer (ROADM) selectively drops and/or adds desired optical channel(s) from and/or to an optical WDM input signal. The ROADM includes a spatial light modulator having a micro-mirror device with an array of micro-mirrors, and a light dispersion element. The micro-mirrors tilt between two positions in response to a control signal provided by a controller in accordance with a switching algorithm and input command. Collimators, diffraction gratings and Fourier lens collectively collimate, separate and focus the optical input channels and optical add channels onto the array of micro-mirrors. Each optical channel is focused on micro-mirrors of the micro-mirror device, which effectively pixelates the optical channels. To drop and/or add an optical channel to the optical input signal, mirrors associated with each desired optical channel are tilted away from a return path to the second position.

Abstract: A reconfigurable optical channel monitor selects and determines a parameter of desired optical channel(s) from and/or to an optical WDM input signal. The OCM includes a spatial light modulator having a micro-mirror device with a two-dimensional array of micro-mirrors that tilt between first and second positions in response to a control signal from a controller in accordance with a switching algorithm and an input command. A collimator, diffraction grating, and Fourier lens collectively converge the optical input channels onto the micro-mirrors array. The optical channel is focused onto a plurality of micro-mirrors. To select each input channel, a group of micro-mirrors associated with each desired input channel is tilted to reflect the desired input channel back along the return path to a photodetector and processing unit to determine a parameter of the selected input signal.