Abstract: One embodiment relates to a method for deghosting seismic data from a marine seismic survey. The seismic data from the marine seismic survey is obtained, where the marine seismic survey was performed using multiple sub-sources towed at two or more different depths and fired at distinct time-delays. The seismic data is sorted into common receiver gathers, and the common receiver gathers are transformed from horizontal source coordinates to horizontal wavenumbers. For each selected frequency, a matrix operator is constructed, and an inversion procedure is applied to a system of equations based on the matrix operator to generate source-deghosted seismic data. Other embodiments, aspects and features are also disclosed.

Abstract: Methods and apparatuses for processing seismic data carrying information about a subsurface structure are provided. One method includes splitting the seismic data in groups, each group including subsets of seismic data for which a distance from a respective shot point to a receiver line in a patch of active detectors corresponding to the shot point is within a predetermined range for the group, and extracting signal data for each block Hankel matrix based on an SVD analysis thereof. Another method includes extracting signal data by subtracting from seismic data an estimated noise model obtained by rank reduction of a Hankel matrix followed by dip filtering, enhanced based on a least square matching filter with the seismic data.

Abstract: A technique provides a source design and method for increasing low frequency output of a marine source array. The approach comprises providing a plurality of airguns. At least some of the airguns are activated to generate an effective bubble energy. The effective bubble energy may be optimized through use, preparation and/or arrangement of the airguns.

Abstract: A steering tool is movable by a drill string to form an underground bore along an intended path. A sensing arrangement of the steering tool detects its pitch and yaw orientations at a series of spaced apart positions along the bore, each position is characterized by a measured extension of the drill string. The steering tool further includes a receiver. At least one marker is positioned proximate to the intended path, for transmitting a rotating dipole field to expose a portion of the intended path to the field for reception by the receiver. The detected pitch orientation, the detected yaw orientation and the measured extension of the drill string are used in conjunction with magnetic information from the receiver to locate the steering tool. The steering tool may automatically use the magnetic information when it is available. A customized overall position determination accuracy can be provided along the intended path.

Abstract: A method and apparatus are provided for making directional measurements toward a formation of different resistivity that is proximate to the borehole, but which is not penetrated by the borehole. The methods and apparatus include the use of at least one insulated gap and at least one magnetometer positioned within a non-magnetic housing that is disposed within a non-magnetic tubular. An electric current is applied across the insulated gap, which results in current leaking into the surrounding formations. When a formation of contrasting resistivity is proximate to the logging apparatus, the magnetometer detects a secondary magnetic field due to the contrasting formation. The direction of the secondary magnetic field can be used to determine the direction to the contrasting formation. The magnitude of the secondary magnetic field can be used to determine the distance position to the contrasting formation.

Abstract: A method for drilling a well includes applying a current across a drill collar that surrounds an internal magnetometer. The current travels across the drill collar and along one or more other current paths to return to the drill collar. The method also includes using the magnetometer to measure magnetic fields due to the current being applied across the drill collar and the current across one or more other current paths while the drill collar is disposed at a first angle of rotation and rotating the drill collar to a second angle of rotation. The method further includes measuring the magnetic fields using the internal magnetometer while the drill collar is disposed at the second angle of rotation and determining a relationship between the current across the drill collar and a portion of the magnetic fields due to the current across the drill collar measurable by the internal magnetometer.

Abstract: Methods and systems that compensate for magnetic interference in azimuthal tool measurements. At least some method embodiments include a downhole logging method that includes taking measurements as a function of orientation from inside a borehole. The measurements are associated with different azimuthal bins, and an azimuthal direction is determined for each azimuthal bin. Because the tool rotates at a constant rate, the relative number of measurements associated which the different bins can be used to measure the effective sizes of the different bins and to redetermine the effective angles of the bins in the presence of magnetic interference. The tool measurements may include, but are not limited to, formation resistivity, magnetic field, and formation density.

Abstract: Apparatus and methods are implemented to determine characteristics of geological formations in a well. One or more transmitters and receivers electrically imitate a moving antenna. The moving antenna produces a distribution of frequencies by utilizing the Doppler effect. Each anomaly in the well produces reflections with different frequency, amplitude and phase information. Location and characteristics of multiple anomalies can be identified simultaneously in a well.

Abstract: Various embodiments include apparatus and methods to detect and locate conductive structures below the earth's surface. Tools can be configured with receiving sensors arranged to receive signals generated from a conductive structure in response to a current flowing on the conductive structure. Magnetic-related values from the signals can be processed, relative to the tool, to determine a position of a conductive structure from which the signal was generated in response to current flowing on the conductive structure. Additional apparatus, systems, and methods are disclosed.

Abstract: A method for estimating a borehole independent porosity of a subterranean formation includes processing a neutron logging data point, preferably including average near and far detector neutron count rates with suitable input data to obtain the porosity estimate. The borehole independent formation porosity may be obtained without any compensation and without any reliance on the measurement or estimation of sensor standoff and/or borehole caliper.

Abstract: Borehole logging methods and apparatuses for estimating formation properties using nuclear radiation, particularly an apparatus and method for estimating amounts of silicon and/or oxygen in the formation. Methods include estimating a formation property using an oxygen estimate and at least a formation lithology. The method may include using nuclear radiation information from at least one nuclear radiation detector generate the oxygen estimate. The apparatus may include at least one nuclear radiation detector. The apparatuses may include an information processing device to perform the methods.

Abstract: The present invention relates to a proximity sensing method for proximity sensing unit in a mobile device. The proximity sensing method comprises steps of comparing a sensed value of the proximity sensing unit with a predetermined offset value or a first predetermined range to determine if the sensed value is smaller than the predetermined offset value or if the sensed value is within the first predetermined range; and providing an offset value for confirming if an object is near the mobile device according to the determination that if the sensed value is smaller than the predetermined offset value or within the first predetermined range.

Abstract: A system and method of mapping underground utilities and other subsurface objects involves one or more of acquiring utility location data using a number of different detectors and sensors, processing the multiple detector/sensor output data to produce mapping data, storing the mapping data in a database, and providing access to and use of the stored mapping data by subscribing users on a usage fee basis.

Abstract: Identifying marks are often used for authentication and tracking purposes with various types of articles, but the marks themselves can sometimes be subject to replication or removal by an outside entity, such as a person or group having malicious intent. This can make it easier for an outside entity to produce a counterfeit article or to sell a stolen article. Carbon nanotubes and other carbon nanomaterials can be used to form identifying marks that are not visible to the naked eye, thereby making the marks more difficult for an outside entity to tamper with. Various articles can include an identifying mark that is localized and not visible to the naked eye, the identifying mark being electrically conductive and containing a carbon nanomaterial. By electrically interrogating the article, such as through spatially measuring eddy currents about the article, the marks can be located and authenticated.

Abstract: A metamaterial-based dispersion compensator includes a plurality of layers arranged in a geometric structure; wherein the plurality of layers comprise engineered metamaterials; wherein the engineered metamaterials and the geometric structure are configured to compensate dispersion across a wavelength spectrum. The metamaterial-based dispersion compensator utilizes a specifically engineered frequency response, in a compact metamaterial form-factor, to correct for naturally occurring and problematic dispersion in physical systems such as in optical communication systems.

Abstract: Presently described are microstructured films, such as brightness enhancing films, having a microstructured surface. The microstructured surface comprises the reaction product of a polymerizable composition comprising at least 20 wt-% of inorganic nanoparticles and a non-aromatic multi-(meth)acrylate monomer comprising at least three contiguous alkylene oxide repeat units. The multi-(meth)acrylate monomer typically comprises two or three (meth)acrylate groups. The alkylene oxide repeat units have the formula —[O-L]- wherein each L is independently a C2-C6 alkylene. Also described is a polymerizable resin composition comprising at least 20 wt-% of inorganic nanoparticles having a refractive index of at least 1.68 and a non-aromatic multi-(meth)acrylate monomer comprising at least three contiguous alkylene oxide repeat units.

Abstract: Presently described are optical films, such as a brightness enhancing film, having a polymerized microstructured surface disposed on a preformed polymeric film wherein the film has a thickness of no greater than 3 mils and the polymerized microstructured surface consists of the reaction product of a substantially non-brominated polymerizable resin composition.

Abstract: The polycarbonate resin of the present invention has a structural unit represented by general formula (A): (in formula (A), X is an alkylene group having 1 to 4 carbon atoms).

Abstract: Silicone hydrogel contact lenses having a high water content are described. The lenses are derived from a polymerizable composition including a first siloxane monomer represented by formula (1): wherein m of formula (1) represents one integer from 3 to 10, n of formula (1) represents one integer from 1 to 10, R1 of formula (1) is an alkyl group having from 1 to 4 carbon atoms, and each R2 of formula (1) is independently either a hydrogen atom or a methyl group; the lenses also include units derived from a second siloxane monomer having a number average molecular weight of at least 7,000 daltons, and at least one vinyl-containing cross-linking agent. The lenses have average equilibrium water contents from about 30% wt/wt to about 70% wt/wt when fully hydrated. Batches of silicone hydrogel contact lenses and methods of making silicone hydrogel contact lenses are also described.

Abstract: [Problem to be Solved] To provide: an antifog optical article wherein a suitable water-repellent layer is formed in the process of application of antifog coating having a water-absorbing layer consisting primarily of urethane or acrylic resin having a polyoxyethylene chain on a base material; and a manufacturing method of the antifog optical article. [Solution] A water-absorbing layer consisting primarily of urethane or acrylic resin having a polyoxyethylene chain represented as —(CH2CH2O)n- is formed on a surface of a glass or plastic base material, a water-repellent layer consisting primarily of at least one of amino-modified silicone and mercapto-modified silicone is formed on a surface of the water-absorbing layer, and a contact angle with respect to water on a surface of the water-repellent layer is set equal to or larger than 100 degrees.

Abstract: Provided are methods of depositing polymer solutions on substrates to form various optical elements. A polymer solution may include about 0.1%-30% by weight of a specific polymer having rigid rod-like molecules. The molecules may include various cores, spacers, and sides groups to ensure their solubility, viscosity, and cross-linking ability. The deposition techniques may include slot die, spray, molding, roll coating, and so forth. Pre-deposition techniques may be used to improve wettability and adhesion of substrates. Post-deposition techniques may include ultraviolet cross-linking, specific drying techniques, evaporation of solvent, treating with salt solutions, and shaping. The disclosed polymers and deposition processes may yield optical elements with high refractive index values, such as greater than 1.6. These optical elements may be used as +A plates, ?C plates, or biaxial polymers and used as retarders in LCD active panels or as light collimators and light guides.

Abstract: Optical devices including deterministic aperiodic patterning using spiral arrays exhibit circular symmetry in continuous Fourier space via polarization-insensitive planar diffraction. Far-field diffractive coupling in these structures leads to the formation of scattering resonances with circular symmetry and characteristic vortex behavior carrying orbital angular momentum. Plasmonic nanoparticle arrays with aperiodic spiral geometry can be used in fabrication of optical devices that benefit from polarization insensitive, enhanced light-matter coupling on planar surfaces, such as thin-film solar cells (enhanced light absorption and efficiency), photodetectors (enhanced light emission and efficiency), optical biosensors, and polarization devices.

Abstract: An optical element 1 comprises a base 2 having a surface 2a formed with a depression 3 and a formed layer 4 disposed on the base 2. The formed layer 4 has a main part 5 located within the depression 3 when seen in the depth direction of the depression 3 and an overhang 6 located on the surface 2a of the base 2 while being connected to the main part 5. A curved surface 4b opposing a bottom face 3b of the depression 3 in the main part 5 is provided with an optical function part 10.

Abstract: Focus of a laser optical system can be corrected using a variable radius mirror having a focusing cavity and a separate cooling cavity. Pressure of a focusing material at a sufficiently low mass flow in the focusing cavity deforms a reflective surface mounted to the focusing cavity, changing its radius. Cooling material provided to the cooling cavity cools the variable radius mirror. A laser beam is reflected by the deformed reflecting surface to focusing optics, focusing the reflected laser beam on an EUV-emitting target, and minimizing a laser focus error by one or more of: maximizing a measured EUV power or minimizing a measured laser beam divergence. Providing focusing material at a deformation pressure and at a sufficiently low mass flow, and providing a separate cooling cavity, avoids perturbations in the reflective surface which would otherwise affect laser beam focus.

Abstract: Methods of forming microelectronic structures are described. Embodiments of those methods may include forming a photomask on a (110) silicon wafer substrate, wherein the photomask comprises a periodic array of parallelogram openings, and then performing a timed wet etch on the (110) silicon wafer substrate to form a diffraction grating structure that is etched into the (110) silicon wafer substrate.

Abstract: A transmitting diffraction element may include a transparent substrate, and a plurality of convex parts periodically formed on one surface of the transparent substrate, and be configured to diffract incident light to the transparent substrate. Each of the convex parts may include first, second, third, and fourth layers that are stacked on the transparent substrate. The first and third layers may be made of a material having a high refractive index, and the second and fourth layers may be made of a material having a low refractive index that is lower than the high refractive index.

Abstract: A method of producing a Fresnel zone plate (15) comprising: making available a substrate (1, 4, 7) which is rotationally symmetrical with respect to its center axis (1a, 4a, 7a); applying layers (2a-d; 5a-d; 8a-d; 11) following in succession by means of an atomic layer deposition (ALD) method to faces (1b-c; 4b-c; 7b-c) of the substrate (1, 4, 7) without rotation of the substrate (1, 4, 7) in order to form a coated substrate, and severing (3a, b; 6a, b; 9a, b) at least one slice (13) from the coated substrate (1, 4, 7), by the coated substrate (1, 4, 7) being divided at least once at a right angle to the center axis (1a, 4a, 7a).

Abstract: The present invention provides polymeric materials arranged as photonic crystals, or portions of photonic crystals, having properties which can be easily tuned over a large range of wavelengths upon exposure to an external stimulus. In some embodiments, the photonic crystals comprise at least one portion which can undergo a change in a physical, chemical, dielectric, or other property upon exposure to an altering stimulus, resulting in a change in a diffracted wavelength of electromagnetic radiation (e.g, light) by the photonic crystal. Embodiments of the invention may advantageously exhibit large stop band tunability and rapid response times. Photonic crystals of the invention may be useful in a wide variety of applications, such as colorimetric sensors, active components of simple display devices, electrically controlled tunable optically pumped laser, photonic switches, multiband filters, and the like.

Abstract: A system and method for acquiring images containing spatial and spectral information of an object include acquiring defocused images using an optical system based on extended depth of field. The optical system further includes a filter array comprising an array of at least six different sub-filters that are arranged such that any group of four immediately adjacent sub-filters includes at least one red sub-filter, at least one green sub-filter and at least one blue sub-filter. The filter array is located at the aperture stop of the optical system. A coded mask is located at the focal plane of the optical system, and an imager is located beyond the focal plane such that images acquired by the imager are defocused. The images are refocused, and spectral and spatial information is restored by designated software.

Abstract: An embodiment of the invention provides a color filter substrate which includes: a substrate having a surface; a light-shielding layer disposed on the surface; a first color filter layer; and a second color filter layer disposed on the surface, the light-shielding layer has a first sidewall in direct contact with the first color filter layer, the first sidewall and the surface form a first angle, the light-shielding layer has a second sidewall in direct contact with the second color filter layer, the second sidewall and the surface form a second angle, and the second angle is less than the first angle.

Abstract: A color filter array for use on a color image sensor includes an oxide grid having sidewalls arranged to define openings in the oxide grid. Each one of the openings is to be disposed over a corresponding pixel cell of the color image sensor. Oxide support structures are disposed in an interior region of each opening in the oxide grid over a corresponding pixel cell of the color image sensor. The openings in the oxide grid are filled with color filter material of a corresponding color filter. A surface tension between each oxide support structure and the surrounding color filter material of the color filter is adapted to provide uniform thickness for the color filters within the corresponding openings in the oxide grid.

Abstract: Provided is a polarizing element having excellent optical properties and high light resistance to intense light. This polarizing element is provided with a transparent substrate, an absorbing layer disposed on the transparent substrate and constituting grid-shaped convexities arrayed at a pitch smaller than the wavelengths in the optical bandwidth used, a dielectric layer formed on the absorbing layer, and a reflective layer formed on the dielectric layer. Because the absorbing layer, which interferes with and absorbs light, is in contact with the transparent substrate, heat dissipation can be improved and heat resistance of the polarizing plate can be improved.

Abstract: A 3D image projector having a translucent rotatable hollow cylinder, the hollow cylinder having differently polarized sections, and the projector being capable of passing a light beam generally orthogonally through a wall of the hollow cylinder is disclosed.

Abstract: The present invention relates to a borate birefringent crystal applicable to ultraviolet (UV) or deep ultraviolet (DUV) range, with chemical formula of Ba2Mg(B3O6)2. The borate birefringent crystal belongs to a trigonal system, with space group of R-3 wherein a=0.70528(3) nm, c=1.65520(9) nm and Z=12. The barium magnesium borate birefringent crystal is negative uniaxial (ne<no) with a birefringence of 0.077-0.229 and a transmission range of 177-3000 nm. The crystal is easy to cut, grind, polish, and preserve, and is stable in air and is not easy to deliquesce. The barium magnesium borate birefringent crystal can be grown by the Czochralski method, flux method or the method of spontaneous crystallization from a melt, and has larger birefringence (no?ne=0.077-0.229). The crystal has important applications in the fields of optics and communications, e.g. for fabricating the polarizing beam splitter prism.

Abstract: A volume holographic imaging system, apparatus and/or method enables the projection of a two-dimensional (2D) slice of a four-dimensional (4D) probing object A 4D probing source object is illuminated to emit or scatter an optical field. A holographic element having one or more recorded holograms receives and diffracts the optical field into a diffracted plane beam having spectral information. A 4-ftelecentric relay system includes a pupil filter on the relayed conjugate plane of the volume hologram and images the pupil of the volume hologram onto the front focal plane of the collector lens. A collector lens focuses the diffracted plane beam to a 2D slice of the 4D probing source object. The focused 2D slice is projected onto a 2D imaging plane. The holographic element may have multiple multiplexed holograms that are arranged to diffract light from the corresponding slice of the 4D probing source object.

Abstract: The present invention relates to a light-emitting fabric, in which acrylic optical fibers and general fibers are woven together, and light is emitted to the surface of the fabric through the optical fibers floating on the surface of the union fabric. According to the present invention, part of the clad portion of the optical fibers is removed by melting so as to prevent the total reflection of the clad portion and to emit high-brightness patterns or characters having a higher brightness than those emitted by optical fibers having a conventional clad portion. Also, a semi-circular core portion is flattened so as to prevent the light from being refracted unnecessarily, and thus the high-brightness light-emitting fabric which can express complex patterns or characters at a higher resolution without emitting environmental pollutants can be provided.

Abstract: A planar light source apparatus includes a point light source and a light guide plate shaped like a flat plate with a rectangular shape in a plan view. The light guide plate includes an output surface confronting an opening portion, a pair of second side surfaces opposed to each other, and a hole opening in a non-output surface and formed near one of the first side surfaces at a position where the point light source is to be arranged. Each of the pair of second side surfaces is at least partially configured as a prism whose ridge line extends in a direction perpendicular to the output surface and whose cross-section, when sectioned in a direction parallel to the output surface, has a sawtooth-like shape in which concavity and convexity are repeated. A light of the point light source can be efficiently uniformized in the light guide plate, and thus unevenness of brightness can be prevented.

Abstract: Provided are quantum dot bar container and backlight unit. According to an aspect of the present invention, there is provided a quantum dot bar container comprising a support including a guide groove formed along a major axis thereof; a cover having a major axis, the cover being orientable to align its major axis substantially parallel to the major axis of the support, the cover including a fixing groove formed along the major axis of the cover so as to face the guide groove; and a fixing portion coupling an end of the support to an end of the cover. The cover and the support are positioned so as to form a window therebetween, when the cover is oriented so that its major axis is substantially parallel to the major axis of the support.

Abstract: The subject matter disclosed herein relates to an optical device comprising: a light guide film to transport light rays via total internal reflection; a first optical layer covering at least a portion of a first side of the light guide film, the first optical layer to receive an exiting portion of the light rays; a second optical layer covering at least a portion of the first optical layer; and a grating pattern located at an interface between the first optical layer and the second optical layer to out-couple light rays travelling in the light guide film, wherein the grating pattern is configured so that the exiting portion of the light rays transmit through the grating pattern twice before being total internally reflected by the grating pattern.

Abstract: A display apparatus comprising a display panel and a light emitting module disposed oppositely is provided. The light emitting module comprises a light guide plate, a plurality of light guide grooves and at least a light unit. The light guide plate has at least a light incident surface, a first surface and a second surface opposite to the first I surface. The light guide grooves are disposed on the first surface. Each light guide groove has a bottom, which is the portion of each light guide groove closest to the second surface, wherein the larger the distance from the bottom to the closest light unit, the smaller the distance from the bottom to the second surface.

Abstract: The invention relates to a mode filter for reducing higher-order modes, with an optical fiber (1), which has a core (2) and a cladding (3) surrounding the latter, wherein the cladding (3) and core (2) have refractive indices that differ from one another. In order to develop an alternative to the prior art, the mode filter according to the invention is designed in such a manner that the fiber (1) has, in a transition region (4) between core (2) and cladding (3), at least one local refractive index modification region (5) which is arranged in the radially outer region of the core (2) and extends into the region of the cladding (3).

Abstract: The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with an index-matching material that is held in a vessel with an integrated interferometer (e.g., phase mask, etc.). The index-matching material has a refractive index that is sufficient to reduce intensity variations of the actinic radiation within the optical fiber. Some embodiments of the system include different vessels for holding the index-matching material, with the vessel having an interferometer integrated into the vessel. These vessels permit the optical fiber to be surrounded by the index-matching material while the gratings are written to the optical fiber.

Abstract: An optical fiber including a multimode core having a radius, R1, and a maximum relative refractive index, ?1MAX, at a wavelength ?0, an inner clad region surrounding the core and having a radial thickness, T2, and a minimum relative refractive index, ?2MIN, of about 0.0% at a wavelength of ?0, and an outer clad layer, which is doped with chlorine at greater than or equal to 0.5 weight %, surrounding the inner clad region and having a radial thickness, T3, and a maximum relative refractive index, ?3MAX, at a wavelength of ?0. The optical fiber satisfies the following relationship: ?1MAX>?3MAX>?2MIN, and the optical fiber exhibits an overfilled bandwidth of greater than or equal to about 1.5 GHz-km at ?0.

Abstract: Embodiments of the invention describe apparatuses, systems, and methods of thermal management for photonic integrated circuits (PICs). Embodiments include a first device and a second device comprising including waveguides, wherein the first and second devices have different thermal operating conditions. A first region is adjacent to a waveguide of the first device, wherein its optical mode is to be substantially confined by the first region, and wherein the first region has a first thermal conductivity to dissipate heat based on the thermal operating condition of the first device. A second region is adjacent to a waveguide of the second device, wherein its optical mode is to be substantially confined by the second region, and wherein the second region has a second thermal conductivity to dissipate heat based on the thermal operating condition of the second device. In some embodiments, thermal cross talk is reduced without significantly affecting optical performance.

Abstract: Provided is a flat-top mode generating device. The flat-top mode generating device includes an input waveguide, a double-tapered structure connected to the input waveguide, and an input star coupler connected to the double-tapered structure. The double-tapered structure includes a first part having a first height hat is equal to that of each of the input waveguide and the input star coupler, and a second part disposed in the first part on the plane and having a second height that is less than the first height, the second part being tapered from the input star coupler toward the input waveguide.

Abstract: A low loss optical crossing and a method of making an optical crossing in a photonic integrated circuit.

Abstract: A method of fabricating a heterogeneous semiconductor wafer includes depositing a III-V type semiconductor epitaxial layer on a first wafer having a semiconductor substrate. The first wafer is then bonded to a second wafer having a patterned silicon layer formed on a semiconductor substrate, wherein the III-V type semiconductor epitaxial layer is bonded to the patterned silicon layer of the second wafer. The semiconductor substrate associated with the first wafer is removed to expose the III-V type semiconductor epitaxial layer.

Abstract: A fiber optic cable assembly includes first and second fiber optic ribbons and a splice protector. The ribbons are spliced together such that the corresponding spliced fibers at the splice have a common lengthwise axis, widthwise axis orthogonal to the lengthwise axis, and thickness axis orthogonal to the lengthwise and widthwise axes. The splice protector supports the ribbons that are spliced to one another at the splice. The splice protector may include or even consist essentially of an adhesive that provides a flexible support for the splice. The splice protector may be at least half as flexible when cured over the splice as the first and second ribbons in bending about the widthwise axis.

Abstract: Techniques are disclosed for improving pump absorption and efficiency for fiber lasers and amplifiers, for instance. In some embodiments, the techniques are implemented by applying a partially reflective coating on a fiber end-face to double-pass any unabsorbed or otherwise excess pump light in the cladding of a fiber. While being reflective to pump wavelengths, the coating can be non-reflective at the lasing wavelength, so as to avoid unwanted feedback into the system. The benefits of this approach include that excess pump power can be effectively utilized to add more power to the laser output. In addition, the double-pass technique allows for the use of a shorter fiber length, which in turn allows for more compact system designs, saves on material costs, and facilitates manufacturability.

Abstract: Optical filters comprising one or more optically-coupled Fabry-Perot resonators are disclosed. In some embodiments, the one or more optically coupled Fabry-Perot resonators include a graded index fiber. In some embodiments, the one or more optically coupled Fabry-Perot resonators are coupled end-to-end, whereas in other embodiments the one or more optically coupled Fabry-Perot resonators are side-coupled through evanescence. One or more implementations of an optical filter allow a spectral response of an input light beam to be controlled, through various approaches, e.g., by exposing a component fiber to ultra-violet radiation.