Cidra Corporation

University System of Maryland

Other

Weatherford/lamb, Inc.

Robert N. Brucato

Alan D. Kersey

James S. Sirkis

Mark R. Fernald

Martin A. Putnam

James S Sirkis

Alan D Kersey

Martin A Putnam

Robert N Brucato

Joseph Francis Pinto

John A Moon

Michael A Davis

James R Dunphy

Mark R Fernald

Timothy J Bailey

Paul Eric Sanders

Paul S Szczepanek

Trevor Wayne MacDougall

James M Sullivan

Charles Winston

Richard Todd Jones

Thomas Wolfgang Engel

Matthew B Miller

Ralph W Jones

Christopher Chestnut

Yaowen Li

Jay Walter Dawson

David Fournier

Christian Victor O'Keefe

Peter C Chen

David R Fournier

Harmeet Singh

Christopher J LaVigna

Ponniah Sivanesan

Venki S Venkat

Harmest Singh

An optical channel monitor is provided that sequentially or selectively filters an optical channel(s)of light from a (WDM) optical input signaland senses predetermined parameters of the each filtered optical signal (e.g., channel power, channel presence, signal-noise-ratio). The OCMis a free-space optical device that includes a collimator assembly, a diffraction gratingand a mirror. A launch pigtail emits into free space the input signal through the collimator assemblyand onto the diffraction grating, which separates spatially each of the optical channelsof the collimated light, and reflects the separated channels of light onto the mirror. A &#x3bb;/4 plateis disposed between the mirrorand the diffraction grating. The mirror reflects the separated light back through the &#x3bb;/4 plateto the diffraction grating, which reflects the channels of light back through the collimating lens. The lensfocuses each separated channel of light (&#x3bb;-&#x3bb;) at a different focal point in space. One of the optical channelsis focused onto a receive pigtail, which then propagates to a photodetector. A pivoting mechanismpivots the diffraction gratingor mirrorabout a pivot pointto sequentially or selectively focus each optical channelto the receive pigtail. A position sensordetects the displacement of the diffraction gratingor mirror.

Optical channel monitor

An optical spectrum analyzer (OSA)sequentially or selectively samples (or filters) a spectral band(s)of light from a broadband optical input signaland measures predetermined optical parameters of the optical signal (e.g., spectral profile) of the input light. The OSAis a free-space optical device that includes a collimator assembly, a diffraction gratingand a mirror. A launch pigtail emits into free space the input signal through the collimator assemblyand onto the diffraction grating, which separates or spreads spatially the collimated input light, and reflects the dispersed light onto the mirror. A &#x3bb;/4 plateis disposed between the mirrorand the diffraction grating. The mirror reflects the separated light back through the &#x3bb;/4 plateto the diffraction grating, which reflects the light back through the collimating lens. The lensfocuses spectral bands of light (&#x3bb;&#x2013;&#x3bb;) at different focal points in space. One of the spectral bandsis focused onto a receive pigtail, which then propagates to a photodetector. A pivoting mechanismpivots the diffraction gratingor mirrorabout a pivot pointto sequentially or selectively focus each spectral bandto the receive pigtail. A position sensordetects the displacement of the diffraction gratingor mirror.

Optical spectrum analyzer

An optical sensing device including a force-applying assembly for providing a force and a Fabry-Perot (FP) element including a large-diameter waveguide having a core and having a cavity in line with the core, the cavity having reflective surfaces and having an optical path length related to the distance between the reflective surfaces, the FP element being coupled to the force so that the optical path length changes according to the force, the FP element for providing an output optical signal containing information about a parameter that relates to the force. Sometimes the large-diameter waveguide is formed by collapsing a glass tube, having a bore and having an outer diameter of about one millimeter, onto a pair of optical fibers arranged in tandem in the bore and separated by a predetermined distance, and respective end faces of the optical fibers form the cavity and are coated with a wholly or partially reflective material.

Fabry-perot sensing element based on a large-diameter optical waveguide

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.

Multifunctional optical device having a spatial light modulator with an array of micromirrors

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.

Tunable optical filter having large diameter optical waveguide with bragg grating and being configured for reducing the bulk modulus of compressibility thereof

An dynamic optical filteris provided to selectively attenuate or filter a wavelength band(s) of light (i.e., optical channel(s)) or a group(s) of wavelength bands of an optical WDM input signalThe optical filter is controllable or programmable to selectively provide a desired filter function. The optical filterincludes a spatial light modulatorwhich comprises an array of micromirrorsthat effectively forms a two-dimensional diffraction grating mounted in a retro-reflecting configuration. Each optical channelis dispersed separately or overlappingly onto the array of micro-mirrorsalong a spectral axis or directionsuch that each optical channel or group of optical channels are spread over a plurality of micromirrors to effectively pixelate each of the optical channels or input signal. Each channelor group of channels may be selectively attenuated by flipping or tilting a selected number of micromirrors to thereby deflect a portion of the incident radiation away from the return optical path. The micro-mirrors operate in a digital manner by flipping between a first and second position in response to a control signalprovided by a controllerin accordance with an attenuation algorithm and an input commandThe switching algorithm may provide a bit (or pixel) map or look-up table indicative of the state of each of the micro-mirrorsof the array to selectively attenuate the input signal and provide a modified output signalat optical fiber

Dynamic optical filter having a spatial light modulator

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.

Optical blocking filter having an array of micro-mirrors

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.

Fabry-perot filter/resonator

Fabry-Perot sensing element based on a large-diameter optical waveguide

An optical filter for filtering a spectral profile of an optical signal for providing an output signal having a desire gain profile, such as a flatten gain profile. The filter comprises an optical waveguide that includes a core disposed within a cladding having an outer dimension greater than 0.3 mm. A Bragg grating is imparted or written in the core of the waveguide that attenuates the received optical input signal in accordance with a defined reflection or transmission filter profile. The Bragg grating may be a slanted grating. The filter profile is complementary to the spectral gain profile of the input signal to provide an output signal having a substantially flat spectral profile of a desired wavelength band. The cladding of the waveguide may have a mechanically advantageous outer geometry (e.g., a &ldquo;dogbone&rdquo; shape) for allowing an axial compressive force to tune the Bragg grating. The waveguide may be package within an athermal device, which tunes the grating to compensate for temperature dependent changes. Further, the waveguide may be packaged in a tuning device to selective tune the gratings to shift the center wavelength of the spectral profile of the filter, or to change the shape of the filter profile.

Optical grating-based filter

A temperature compensated optical device includes a compression-tuned glass element having a Bragg grating therein, a compensating material spacer and an end cap all held within an outer shell The element end cap and shell are made of a material having a low coefficient of thermal expansion (CTE), e.g., silica, quartz, etc. and the spacer is made of a material having a higher CTE, e.g., metal, Pyrex&reg;, ceramic, etc. The material and length L of the spacer is selected to offset the upward grating wavelength shift due to temperature. As temperature rises, the spacer expands faster than the silica structure causing a compressive strain to be exerted on the element which shifts the wavelength of the grating down to balance the intrinsic temperature induces wavelength shift up. As a result, the grating wavelength is substantially unchanged over a wide temperature range. The element includes either an optical fiber having at least one Bragg grating impressed therein encased within and fused to at least a portion of a glass capillary tube or a large diameter waveguide (or cane) with a grating having a core and a wide cladding, which does not buckle over a large range of compressive axial strains. The element may have a &ldquo;dogbone&rdquo; shape to amplify compressive strain on the grating The device may also be placed in an axially tunable system that allows the wavelength to be dynamically tuned while remaining athermal. In addition to a grating, the device may be an athermal laser, DFB laser, etc. Also, the entire device may be all made of monolithic glass materials.

Temperature compensated optical device

A tunable external cavity semiconductor laser incorporating a tunable Bragg grating, including: a semiconductor gain medium; an elongated tuner housing having a tuner housing head and having a tuner housing foot, the tuner housing head and tuner housing foot being rigidly connected; a span of waveguide having a Bragg grating, for receiving the source light and for providing in turn the reflected light, and having a waveguide head and a waveguide foot, the waveguide head abutting the tuner housing head and the waveguide foot disposed toward the tuner housing foot; a piezoelectric crystal or other device or arrangement for providing a compressive force, disposed so as to abut the waveguide foot and also to abut the tuner housing foot, the means for applying a compressive force for exerting a compressive force on the span of waveguide along the direction of the axis of the span of waveguide, the compressive force being sufficient to alter the grating so as to affect the wavelength of light reflected by the grating. In some applications, the waveguide includes sections of different thicknesses, each having a sampled grating, the two sampled gratings being created so that at any given compressive force exerted by the piezoelectric crystal, the two gratings reflect at most one wavelength in common. The tunable laser in such an application therefore behaves as a stepped tunable laser.

Tunable external cavity semiconductor laser incorporating a tunable bragg grating

An athermal grating design has a Bragg grating unit and a lever arrangement. In operation, the Bragg grating unit responds to an optical signal, a change of temperature and a lever force for offsetting thermally-induced changes in the Bragg grating unit, for providing a grating signal that does not change in relation to change of temperature. The lever arrangement responds to a change of temperature, for providing the level force to the grating to compensate for the change in the temperature. The Bragg grating unit includes a large diameter waveguide cane structure. The lever arrangement may include a top plate, a bottom plate, a lever arm pivotally coupled between the top plate and the bottom plate, and a rod coupled between the top plate and the bottom plate on one side of the lever arm. The Bragg grating unit is arranged between the top plate and the bottom plate on another side of the lever arm. The level arm and the rod have different coefficients of expansion.

Athermal bragg grating package with course and fine mechanical tuning

A Bragg grating sensor for measuring distributed strain and temperature at the same time comprises an optical fiber having a single mode operating wavelength region and below a cutoff wavelength of the fiber having a multimode operating wavelength region. A saturated, higher order Bragg grating having first and second order Bragg conditions is fabricated in the optical fiber. The first order of Bragg resonance wavelength of the Bragg grating is within the single mode operating wavelength region of the optical fiber and the second order of Bragg resonance wavelength is below the cutoff wavelength of the fiber within the multimode operating wavelength region. The reflectivities of the saturated Bragg grating at the first and second order Bragg conditions are less than two orders of magnitude of one another. In use, the first and second order Bragg conditions are simultaneously created in the sensor at the respective wavelengths and a signal from the sensor is demodulated with respect to each of the wavelengths corresponding to the first and second order Bragg conditions. Two Bragg conditions have different responsivities to strain and temperature, thus allowing two equations for axial strain and temperature to be found in terms of the measure shifts in the primary and second order Bragg wavelengths. This system of equations can be solved for strain and temperature.

Measurement of distributed strain and temperature based on higher order and higher mode Bragg conditions

A fiber optic measurement system capable of greatly improving the cost, complexity, and efficiency with which flexible body shape estimates are made. The fiber optic shape measurement system uses Bragg grating sensor technology and time, spatial, and wavelength division multiplexing, to produce a plurality of strain measurements along one fiber path. Using a plurality of fibers, shape determination of the body and the tow cable can be made with minimal ambiguity. Also disclosed is a method to resolve the body shape based on strain-to-shape structural analysis. Possible applications include, but are not limited to, sensing the shape and position of flexible bodies, aid in improving the efficiency of existing acoustic surveying processing techniques, and related applications in geophysical prospecting.

Growing community of inventors

Burtonsville, MD, United States of America

James S Sirkis