Abstract: An apparatus comprising an optical transmitter, a coarse tuner coupled to the optical transmitter and having a first tuning range, a fine tuner coupled to the optical transmitter and having a second tuning range smaller than and within the first tuning range, a wavelength division demultiplexer coupled to the optical transmitter and to a plurality of optical fibers, and a detector coupled to the optical transmitter and the wavelength division demultiplexer.

Abstract: A fiber optic sensor based on spiral structure is a multi-loop spiral member formed by spring wire. A plurality of deformation teeth are continuously distributed on the upper surface and the lower surface (12) of the spring wire in a longitudinal direction along the spring wire; in two adjacent loops of the spring wire, the deformation teeth on the lower surface of the upper loop of the spring wire and the deformation teeth on the upper surface of the lower loop of the spring wire correspond to each other in a staggered way. A signal optical fiber is clamped between the deformation teeth on the lower surface of the upper loop of the spring wire and the deformation teeth on the upper surface of the lower loop of the spring wire, and connected to a test unit (5) by a transmission optical fiber.

Abstract: An apparatus comprising an optical transmitter, a coarse tuner coupled to the optical transmitter and having a first tuning range, a fine tuner coupled to the optical transmitter and having a second tuning range smaller than and within the first tuning range, a wavelength division demultiplexer coupled to the optical transmitter and to a plurality of optical fibers, and a detector coupled to the optical transmitter and the wavelength division demultiplexer. A network component comprising at least one processor configured to implement a method comprising detecting an Optical Time Domain Reflectometry (OTDR) signal spectrum that has a modulated pattern, and detecting a reflected OTDR signal spectrum that has a shifted modulated pattern comprising a frequency shift with respect to the OTDR signal spectrum and a time shift proportional to the frequency shift.

Abstract: A design and manufacturing methods for reusable, stackable shipping containers made from composite materials is described. The composite material is embedded with optical fibers, data and electrical paths, and various types of components. These embedded devices are capable of detecting intrusions through the container walls, securely storing and processing information, and securely communicating information to other containers and to remote devices.

Abstract: The damage length measurement system has an object being measured that comprises a plurality of members is vibrated by an oscillator, and the vibration that propagates through the object being measured is detected by three sensors. A measurement apparatus analyzes that vibration wave, and measures the arrival time of the maximum peak. Using the fact that the time for a wave to propagate between two vibration detection sensors separated by a set interval is fixed, the measurement apparatus determines whether the difference in arrival time between two sensors is within a set reference range that includes the vibration propagation time between two vibration sensors. When the measurement apparatus determines that the difference is not within the set reference range, uses the fact that that wave is delayed compared to the wave that was to be detected.

Abstract: A device having two sets of raised portions inside a metal case is provided for bending an optic fiber. According to some embodiments, the two sets of raised portions are on two plates that are biased apart by a spring means. According to some embodiments, the metal case prevents viewing of an optic fiber in the metal case. According to some embodiments, an adjustable stopping element is provided to limit movement of the two plates toward each other.

Abstract: To allow more reliable detection of occupancy of a seat by a person, the invention includes a detection device for detecting occupancy of a seat, in particular of a vehicle seat or motor vehicle seat, comprising at least one elongate light guide having at least one elongate core element and at least one elongate sheath at a distance from the core element. The light guide is deformable by mechanical actuation means in at least one direction running perpendicular to the longitudinal axis of the light guide by the deformation brought about by the seat being occupied causes the light to exit from the light guide on the side opposite the mechanical means.

Abstract: The general field of the invention is that of fiber-optic sensors comprising at least one measurement optical fiber having an optically pumped doped amplifying medium, the optical characteristics of which are sensitive to a physical quantity, the fiber having at least one Bragg grating. The fiber is designed so as to generate, in the amplifying medium, two optical waves having different optical frequencies that propagate in the same direction after reflection on the Bragg grating and are emitted by the amplifying medium, the two optical frequencies depending on the physical quantity. The two waves may be generated using either a birefringent polarization-maintaining fiber or a DBR (Distributed Bragg Reflector) laser cavity. Notably, this sensor may be used as a hydrophone.

Abstract: Fibre substrates act as a conduit for light along which response signals are transmitted to a controller in the form of an electronic device associated with a component. The processed signals are stored in a local memory to provide a component history and a prediction of future performance and life. Service and repair history may be added to the component device memory to enable a complete history to be stored with the component. A controller may transmit data to an external controller or display through typically a wireless connection. Power to the component electronics may be provided by an induction loop or transformer.

Abstract: Calibration methods and apparatuses for a shape sensing optical fiber are disclosed. Strain is sensed in an optical fiber that is associated with a kinematic chain, and information derived from the sensed strain is used to determine a calibration relationship between the fiber and the kinematic chain. The strain may be sensed at a plurality of angles between two links in the kinematic chain. The strain may be sensed in a segment of the optical fiber that is associated with a joint in the kinematic chain as the joint sweeps through an arc. The strain may be sensed for the optical fiber in a known, predefined bend shape. The calibration information is stored in memory for later use during operation of the kinematic chain, so that shape information from the optical fiber can be used to accurately indicate the shape or pose of the kinematic chain.

Abstract: A connector apparatus for use with combined electrical and fiber optic cables in wet or undersea conditions. The connector apparatus includes an outer threaded male connector portion connected to a first cable and a compatible female connector portion having a rotating internally threaded collar for engaging the outer male connector portion. The female connector portion includes conductor pins and a fiber-optic terminal pin and a fiber optic sensor ring.

Abstract: A method of monitoring the integrity of a hull of an aircraft or a submarine comprising placing an optical fiber network over at least an outer portion of a hull and connecting fiber optic cable instrumentation and a light source to said optical fiber network and, monitoring the integrity of the hull using the instrumentation and the light source.

Abstract: A security system is disclosed for detecting intrusions at a plurality of predetermined locations having moveable closure members. The system comprises a plurality of intrusion sensors disposed at the locations for detecting movement of the closure members. Primary and secondary optical fiber sensor lines are routed through the intrusion sensors, and primary and secondary scanning units pulse signals along the sensor lines and receive reflected signals back from the sensor lines. A processor processes the reflected signals to determine if a reflection and/or attenuation change has occurred in a reflected pulse signal signifying a prescribed level of unauthorized intrusion activity which matches a signature intrusion signal. In the event of a cut through in the sensor lines, the primary sensor line monitors the sensors downstream of the break, and the secondary sensor line is activated to monitor the sensors upstream of the break.

Abstract: Methods and apparatus for predicting service life of remote equipment for infiltration of liquid are disclosed. Such methods and apparatus preferably include at least one fiber optic sensor assembly adapted to react after being exposed to a predetermined quantity of liquid.

Abstract: A collision detection sensor for detecting a collision of a vehicle and a collision object by converting the collision into a change in optical transmission characteristics of an optical fiber. The collision detection sensor has the optical fiber, a molding material formed on the periphery of the optical fiber, and a convex portion formed on the surface of the molding material.

Abstract: Disclosed is a sensor capable of measuring motion in a harsh environment. The sensor uses a fiber optic sensor element formed within a core of an optical fiber that is disposed within an enclosure made of a high strength, corrosion-resistant material. The optical fiber is attached to a supporting fixture in a cantilever fashion so that the intrinsic internal mass of the optical fiber has the freedom to be affected by gravity so that an environmental disturbance acting on the sensor results in a bending strain being applied to the optical fiber. A Bragg grating is located at the bending portion of the optical fiber. The modulation of an optical signal promulgating through the optical fiber is sensed using conventional means and used to measure the magnitude of the environmental disturbance.

Abstract: A distributed fiber optic sensor device that employs a photonic band gap fiber as a sensing medium, in which: the photonic band gap fiber, which is the sensing medium, includes: a quartz section; and a plurality of high refractive index portions provided in the quartz section along the longitudinal direction of the fiber, the high refractive index portions being photonic band gaps periodically arranged to form a triangular-lattice pattern; the photonic band gap fiber has a bandwidth in which a wavelength band of a Stokes beam generated due to stimulated Raman scattering is included; and the photonic band gap fiber has a band gap width in which a wavelength band of an anti-Stokes beam generated due to the stimulated Raman scattering and a wavelength band of an optical signal incident into the photonic band gap fiber are included.

Abstract: Optical time domain reflectometry caused by absorption of a volatile or analyte into the fiber optic cladding is used an optical nose. The fiber optics (14) are covered with a gas permeable film (44) which is patterned to leave millimeter wide gas permeable notches (48a-48d). The notches contain a sensing polymer that responds to different gases by expanding or contracting.

Abstract: This disclosure generally pertains to a method for manufacturing a distributed optical fiber scrim comprising a functional optical fiber, the functional optical fiber scrim thus manufactured, and composites in which an optical fiber scrim is incorporated. The present disclosure describes a variety of textile scrims, particularly adhesively bonded nonwoven scrim materials, each comprising at least one optical fiber with a continuous path across at least the length or width of the fabric. Such optical fiber scrims may be useful as sensor components (for example, as a detector of breakage, strain, pressure, or torque), as illumination components (for example, in a variety of light-providing applications), or as data-distribution components, either alone or in combination with other materials, such as fabrics, films, foams, and the like.

Abstract: A device and method for operating an optoelectronic safety sensitive edge (100) for the safeguarded motor-driven movement of a gate having a closing edge (141). The device has a deformable, hollow, elastic profile (110), a light transmitter device with a light transmitter (121a), and a transmitter control system (121b), by means of which at least one operating parameter of the light transmitter (121a) can be adjusted, a light receiver device (122) with a light receiver, the light transmitter device and the light receiver device (122) being coupled optically and electrically by the transfer of dynamic signals, an optical, dynamic coupling signal (K2, K2?, K2?) within the hollow profile (110); and an evaluating device (130) with means for detecting an electric, dynamic coupling signal (K2, K2?, K2?), the evaluating device (130), generating a release signal in response to the detected, dynamic, electric coupling signal.

Abstract: An optical positioning monitoring system is disclosed. The system has an optical sensing member disposed on a wellbore pipe, such as the tubing or production casing. When a tool comprising an actuating member acts on the optical sensing member, an optical signal is returnable from the optical sensing member indicating the position of the tool. The optical sensing member may include an optical fiber and/or any known optical sensors. The actuating member can be a force applicator or a heat applicator. Alternatively, the optical sensing member can be located on the tool and the actuating member can be located on the tubing or production casing.

Abstract: An input device includes an optical waveguide, one or more light sources, one or more imaging sensors, and a translator. The optical waveguide has an input surface, a back surface substantially opposite the input surface, and a side surface therebetween. The input surface has a plurality of different input locations. The one or more light sources are positioned to introduce light into the optical waveguide. A distortion of each different input location of the input surface causes a portion of light within the optical waveguide to exit from the optical waveguide at a different escape location of the side surface. The one or more imaging sensors are positioned and aimed to detect an escape location of a portion of light exiting from the side surface. The translator determines an input location corresponding to the escape location for each detected escape location.

Abstract: An optical fiber strain-temperature sensing system includes first and second optical sources respectively generating first and second light signals having different wavelengths. Optical circulators direct the light signals to an external sensing cable for the respective generation of first and second Brillouin scattered light signals. First and second frequency mixers have a first input respectively coupled to the first and second optical light sources. The optical circulators direct the first and second Brillouin scattered light signals respectively to second inputs of the first and second frequency mixers. First and second transducers are respectively coupled to an output of the first and second frequency mixers and are respectively configured for generating first and second electrical signals indicative of a Brillouin frequency shift of the first and second light signals.

Abstract: An intensity modulated broadband optical signal source is arranged to produce optical signals in a plurality of wavelength bands. A demultiplexer/multiplexer pair receives optical signals from the optical signal source and produces a separate optical signal for each wavelength band. An optical coupler is arranged to receive the separate optical signals. Optical fiber loops connected to the optical coupler guides both clockwise and counter clockwise waves for each of the separate optical signals. The optical signals propagate through a sensor in each loop and then combine in the optical coupler to form a plurality of interference signals in each wavelength band. A multiplexer is optically coupled to the optical coupler to receive the interference signals therefrom, and a detector array having a selected detector corresponding to the each of the plurality of wavelength bands is arranged to provide an electrical signal that indicates the interference signals for each wavelength band.

Abstract: A spatially distributed sensor system has an optical transmitter, an optical conduit optically coupled to the optical transmitter at an input position, and a sensing element optically coupled to the optical conduit at a position along the optical conduit spatially separated from the input position. The sensing element is structured to split off a fraction of light from the optical transmitter upon being coupled into the optical conduit and to return light to the optical conduit. The spatially distributed sensor system also has an optical receiver coupled to the optical conduit to receive at least a portion of light from the optical conduit that includes light returned to the optical conduit from the sensing element. An analysis of light received by the optical receiver provides information to determine a position of the sensing element.

Abstract: A damage detection system including: a optical fiber sensor including a core portion to have a grating portion formed therein, the grating portion having gratings reflecting light, wherein a wavelength band of the reflected light changes when a distance between adjacent gratings changes; a light source to input broadband light into the core portion; two optical filters connected to an output end of the sensor; and an apparatus to perform arithmetic processing on output values of the optical filters, wherein each passband of the optical filters overlaps with the vibration range of the wavelength band, in which a center wavelength of one of the passbands is fixed to an upper area of a vibration center of a center wavelength of the reflected light and that of the other of the passbands is fixed to a lower area thereof.

Abstract: A method of detecting collisions between elements in a medical procedure such as between a magnet and another element in the procedure mounting on the medical device a flexible body within which is mounted one or more parallel side by side optical fibers arranged such that the impact causes bending of one or more of the optical fibers and detecting changes in light transmission through the optical fiber to detect the bending and thus the collision. The single fiber or fibers are located in a junction between a lower body of resilient foam and a surface layer of a stiffer flexible material.

Abstract: The present invention measures the strain caused by the shrink and expansion from the corrosion and examines the corrosion of a tendon for a long term with high sensitivity to improve the accuracy of the examination.

Abstract: A modular sensor for damage detection with an optical fiber (FBG sensor) to detect a damage of a composite material, having a high level of visibility and manageability, and its manufacturing method is described. A structural composite material embedded with this modular sensor for damage detection is also described.

Abstract: The present invention is directed to a hitpoint sensor for a surface of interest, the hitpoint sensor having an optical fiber which is wound around or otherwise covering the surface, and a data processor connected to the ends of the optical fiber. When a collision with the surface occurs, light is generated which passes through the optical fiber. The ends of the fiber are connected to the data processor which uses arrival time information of the light signals arriving at the processor to determine the impact location on the surface. There are several modes in which the processor can operate to make this calculation.

Abstract: A modular sensor for damage detection with an optical fiber (FBG sensor) to detect a damage of a composite material, having a high level of visibility and manageability, and its manufacturing method is described. A structural composite material embedded with this modular sensor for damage detection is also described.

Abstract: An inflatable sheet includes an optical fiber extending across at least a portion of its surface to detect a breach or nuclear radiation. The sheet can line at least a portion of a container or several such sheets can line several walls of the container. A breach of the sheet or radiation within or near the sheet reduces optical transmissibility of the fiber. The fiber integrates the radiation over time and/or over the length and volumetric mass of the fiber, making the fiber sensitive to even low-level radiation. The optical fiber is monitored for a change in its transmissibility. A reduction in the transmissibility, such as to below a threshold, can trigger an alarm, such as an annunciator, a self-destruct circuit or send a message that includes information about the time or the container's contents or location when the breach or radiation is detected to a central location, such as a ship's control room or port notification system.

Abstract: Intrusion by climbing or jumping over a fence can be detected, and intrusion is detected in a wide area without large-scale equipment. FBGs (grating sections) of different types having different refractive indexes of fiber glass are arranged at predetermined intervals in a longitudinal direction of optical fibers 12, 13A, and 13B, the optical fibers are laid down between poles on the top of a fence or a side thereof, reflected waves from the FBGs are issued by photodetection devices 14, 15A, and 15B in response to an optical input to the optical fibers, and a wavelength shift detection device 16 detects a position of an FBG which exhibits a wavelength shift by swinging of the optical fibers by a stress acting on the fence.

Abstract: A high-voltage component, having a first end and a second end, whereby the first end is on a high-voltage potential with respect to the second end. An insulating part, is arranged between the first end and the second end, and an optical fiber is integrated in the high-voltage component and extends from the first end to the second end. A capillary extends from the first end to the second end and is arranged within the insulating part. The inside diameter of the capillary exceeds the outside diameter of the fiber, and the fiber is arranged within the capillary. The capillary includes a protective medium to achieve a dielectric strength in the capillary, which dielectric strength is suitable for the operating conditions.

Abstract: An apparatus includes a multicore fiber including three cores. The three cores include two pairs of cores, each pair of cores lying in a plane. The planes of the two pairs of cores are non-coplanar. The multicore fiber includes a rosette, the rosette including three coplanar interferometers. Each interferometer of the three interferometers are located in a respective core of the three cores. Each interferometer includes a first reflector and a second reflector. The first reflectors of the rosette are coplanar. The second reflectors of the rosette are coplanar.

Abstract: A compact, long lasting sensor for measuring components such as moisture in moving sheets including paper in a papermaking apparatus employs light sources that produce radiation within defined wavelength regions of interest and the light sources are modulated at high frequencies using non-mechanical techniques. A single detector with various radiation sources can measure at all frequencies while keeping information separated. Superluminescent light emitting diode or laser diode light sources can be directly electrically modulates for improved noise rejection. These higher power and bright light sources afford excellent fiber optic launch efficiency and permits the sensor to be scanned at much faster rates over the paper being monitored.

Abstract: The present invention is directed to an article comprising a thermoplastic polymer film and a discontinuous metallic nanoparticle coating, of an average size less than 100 nm, and the process for preparing the same. The coated film may be further stretched or shrunk to shift the absorbance peak maximum to the desired degree. The coating is formed by depositing a discontinuous layer of metallic nanoparticles by a physical vapor deposition method.

Abstract: A security bar providing improved security from breach is obtained with the use of a fiber optic cable longitudinally inserted in a hollowed out cavity thereof. Monitoring of the security bar to identify attempts at breach thereof may be achieved by connecting an optical light source to one end of the fiber optic cable and a light monitoring device (i.e., an optical receiver) at the other end. In this manner, a breach of the security bar is identified when the optical receiver fails to receive the light generated by the optical light source. In one embodiment, an isolator which consists of a material that is soft enough to absorb a potential shock but hard enough to break or splinter if the security bar is substantially deformed (e.g., wood) surrounds the fiber optic cable.

Abstract: The invention provides a fiber-optic sensing system, utilizing a fiber-grating-based sensor, for a physical parameter, e.g., a pressure or a temperature. Different kinds of fiber-grating-based sensors may be used for this purpose but in-fiber gratings such as Fiber Bragg Grating, Long Period Grating and Surface Corrugated Long Period Fiber Grating are particularly suitable. Due to the small size of the optical fiber and the fact that same fiber acts as the sensing element as well as the signal conducting medium, it is possible to install the sensor in a small diameter needle which is commonly used for medical diagnosis and treatment. As a result, when the fiber-optic sensing system of the invention is used for in-vivo measurement of a biological parameter, such a sensing needle can be used for different in-vivo pressure or temperature sensing applications without causing too much harm and discomfort to the subject tested.

Abstract: Damage caused to a structural composite material is detected while reduction in the strength thereof is prevented. A damage detection system 10 for a structural composite material includes a vibration application apparatus 20 including: a sheet body 22; a plurality of piezo elements 21 sprinkled throughout and held by the sheet body 22; and wires 23 for the piezo elements 21 provided to the sheet body 22. The damage detection system 10 also includes: a fiber optic sensor 30 which includes a grating portion 33 in a core portion 32 thereof, the grating portion 33 reflecting light of a predetermined wavelength; a light source to perform light irradiation onto the core portion 32; and a characteristic detection unit 42 to detect a characteristic of the light reflected from the grating portion 33.

Abstract: Integral fiber optic-based condition sensors detect conditions of a composite structure, e.g., a coated wire assembly so as to detect damage or conditions that may damage the same. Preferably, at least one optical fiber sensor having a plurality of Bragg gratings written into the fiber at spaced-apart locations along its axial length is integrated into the electrical insulator coating of a wire, wire bundle or wiring harness. The fiber optic sensor may thus be employed to measure the environmental loads on the electrical wiring including stresses from bending, axial loading, pinch points, high temperature excursions and chemical damage. The system is capable of detecting and locating transient conditions that might cause damage to a wiring system or permanent changes in state associated with damage events. The residual stress in the electrical insulator coating of a wire, wire bundle, or wiring harness are used to monitor the evolution of damage by wear or chaffing processes.

Abstract: The present invention relates to a method and a device for determining the cut-off wavelength of an optical fiber. A first aspect of the present invention is to provide a method for determining the cut-off wavelength of an optical fiber, which method provides a stable measurement, which measurement is substantially independent of the exact fiber position.

Abstract: Fiber Bragg gratings (FBG) seismic activity sensors coupled in sensor arrays provide increased sensitivity to seismic activities, lower strain values and an absence of EMI allowing detection of troop and vehicle movements based on ground vibrations generating seismic signals. The FBG sensor head features a spring-mass configuration with a head surface, fiber optic cable and the FBG sensor attached to a spring that stretches during the acceleration of the mass. Waves propagating inside the earth and along the ground arriving at the sensor locations cause movement of the seismic activity sensors embedded in the ground and this movement induces an acceleration-dependent change in the FBG gratings placed on the sensors. In multiple sensor configurations, the cable will be connected to the other sensors in the network. FBG sensors, sensor arrays and sensor methods are provided in several embodiments.

Abstract: An apparatus and methods are disclosed for using optical sensors to determine the position of a movable flow control element in a well control tool. A housing has a movable element disposed within such that the element movement controls the flow through the tool. An optical sensing system senses the movement of the element. Optical sensors are employed that use Bragg grating reflections, time domain reflectometry, and line scanning techniques to determine the element position. A surface or downhole processor is used to interpret the sensor signals.

Abstract: A pressure-sensitive sensor which is a load detecting device of the present invention is structured to include: an optical fiber of a predetermined length; a light-emitting element, disposed at a longitudinal direction one end side of the optical fiber, for emitting light and making the light incident from one end of the optical fiber; a light-receiving element, disposed at a longitudinal direction other end side of the optical fiber, for receiving light which has passed through the optical fiber and outputting a signal corresponding to an amount of received light; and a power source wire for light-emission and a ground wire for light-emission which are wound around an outer periphery of the optical fiber, and are formed in spiral forms along the outer periphery, and are connected to the light-emitting element.

Abstract: Provided is a single-mode optical fiber that propagates an optical signal at a wavelength of 1310 nm, in single-mode operation; has a mode field diameter of 6.6 ?m or more at the wavelength of 1310 nm; and a macro bending loss of at most 0.1 dB/10 turns with a bending radius of 7.5 mm at a wavelength of 1650 nm.

Abstract: The sensor interface includes a sensor, an optical fiber, a Bragg grating disposed on the optical fiber, and an optoelectronic circuit. The sensor communicates with the Bragg grating such that the sensor imposes a strain on the Bragg grating that is a function of the parameter sensed. The optoelectronic circuit reads the sensor by interrogating the Bragg grating with a light pulse carried by the optical fiber and detecting the timing and/or frequency of the light reflected by the Bragg grating. The timing and/or frequency of the light reflected is a function of the strain imposed on the Bragg grating.

Abstract: Flexible joint which is used for the repair during the production of metallic tubes which enclose loosely inside them optical fibers, surrounded by a suitable filling material or for the connection of long lengths of the above mentioned tubes during the manufacturing of submarine cables which contain these tubes. The joint comprises a connecting metallic tube (6), which connects externally with overlapping at its ends the metallic tubes (3, 10) after splicing is performed between the optical fibers which they enclose and which are separated in bundles (1, 2). The mechanical connection of the joint is achieved through plastic deformation of the over-applied connecting metallic tube by creating grooved rings (11) at the sections where it overlaps the metallic tubes to be connected (3,10). The water tightness of the joint is obtained by welding the ends (8) of the over-applied connecting metallic tube (6) to the external surface of the metallic tubes to be connected (3, 10).

Abstract: A microbend accelerometer comprising a housing having a housing base and a housing top, where housing base has corrugations that protrude from the surface of the housing and an internal mass assembly located between the housing top and the side of the housing base. The internal mass assembly features corrugations that are similar to the housing base corrugations. The microbend accelerometer also features a sensing fiber featuring light propagating therethrough, said sensing fiber disposed between said internal mass and said housing base, said sensing fiber being coupled on each end to at least one lead fiber. Upon an acceleration event along a predetermined axis, inertia causes the internal mass assembly to apply a force on the sensing fiber causing the sensing fiber to distort. This resulting distortion of the sensing fiber causes the intensity of the light propagating through the sensing fiber to modulate in proportion to the magnitude of said acceleration event.

Abstract: A device for attenuating cladding modes in a single mode optical fiber is disclosed. The device comprises two supports, each equipped with spaced apart corrugations. The optical fiber lies transversely across the corrugations and the two supports are clamped together to impart micro-bends to the optical fiber. The resulting micro-bends provide excellent cladding mode attenuation and the spacing of the corrugations and support members can be adjusted so that the core modes are not attenuated.