The invention relates to a device for optical applications, which has an optical waveguide (10), to which a light source (11) can be connected. The optical waveguide (10) is designed in such a way that light emitted by the connectable light source (11) propagates along a light propagation axis (12). A wavelength-sensitive grating structure (13) in the optical waveguide (10) has detectors (20), which are arranged in such a way that the detectors absorb partial amounts of the light of the light source (11) that is scattered by the wavelength-sensitive grating structure (13). The grating structure (13) in the optical waveguide (10) is constructed of periodically arranged ellipsoid structural elements (14). The ellipsoid structural elements (14) have a different index of refraction than the material of the optical waveguide (10) surrounding the ellipsoid structural elements. The ellipsoid structural elements (14) have a longitudinal axis and a short axis, which are substantially perpendicular to the light propagation axis (12). Depending on the wavelength, partial amounts of the light scattered by the grating structure (13) are coupled out of the optical waveguide (10). The light hits the detectors (20). An absorbing or partially reflecting filter (30) is arranged between at least one of the detectors (20) and the optical waveguide (10). The detectors (20) have measuring elements for the intensity of the partial amount of the light that hits the detector (20) in question. An evaluation element is provided, which determines a wavelength from the intensity ratio of the plurality of detectors (20). The detectors (20) are arranged in such a way that the detectors either are arranged opposite each other on different sides of the long axes of the

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.

A subsurface impact protection system for protecting an underground asset is provided. The protection system includes a subsurface polymer layer provided above the asset to prevent impact forces from reaching the asset. A sensor network is embedded in the polymer layer. The sensor network comprises optical fibers each including one or more fiber optic sensors. The optical fibers receive an input signal from a source and transmit it through the fiber. At the output end of the fiber is an optical detector that measures light properties of the output optical signal indicative of environmental conditions near the polymer layer. The sensor network transmits a signal including measured light or environmental parameters to a monitoring computing system. In some embodiments, the polymer layer includes a protective mesh made up of a plurality of high density polyethylene strands in a woven pattern. A method of protecting an underground asset is also provided.

An EHz ultrafast modulated pulse scanning laser and a distributed fiber sensing system. A plurality of phase-shift gratings are engraved on a doped fiber, the phase-shift gratings having different central window wavelengths and a wavelength interval between the adjacent central window wavelengths being a preset fixed value. When a pump light emitted by a pump laser source is coupled by a wavelength division multiplexer and enters the doped fiber, a single-mode narrow-linewidth laser light having multiple wavelengths with a wavelength interval being a preset fixed value can be generated, by using the phase-shift gratings graved on the doped fiber. The ultrafast modulation is completed by using a time-domain control method based on an EOM. An internally frequency converted pulse light formed by splicing pulse lights whose frequencies linearly increase is obtained, thus forming the EHz ultrafast modulation of a distributed feedback fiber laser. In this way, a coherence length of an output laser light is increased while a frequency of the laser light is remained.

The invention declares a FBG (fiber Bragg grating) intelligent device and method for monitoring coal level in bunker. The device comprises a support device located above the bunker and detachably connected with a vibration device. The vibration device, with a surrounding reserved groove on its shell, extends into the bunker, and the groove is used for embedding FBG sensing device which is connected with FBG Network Demodulator. The Demodulator is electrically connected with a data processing system which is electrically connected with an alarm device, and the alarm device is connected with the belt conveyer. The invention relates to wavelength drifts of FGB, which has fast response and high precision, and can transmit signals to the display device first, providing good operating environment for the bunker.

An endoscope can include an elongated endoscope body. An optical fiber can extend along the endoscope body. The optical fiber can direct therapeutic light and illumination light longitudinally along the optical fiber to a distal portion of the endoscope body. The therapeutic light and the illumination light can have different wavelengths. A wavelength-sensitive light separator, disposed at a distal portion of the optical fiber, can direct the illumination light to exit the optical fiber laterally through a lateral side of the optical fiber at the distal portion of the optical fiber and permit the therapeutic light to exit the optical fiber longitudinally through a distal end of the optical fiber. Examples of suitable wavelength-sensitive light separators can include one or more fiber Bragg gratings that can be obliquely angled, or a diffraction grating disposed on a lateral edge of a length of coreless fiber.

Example embodiments include an optical interrogation system with a sensing fiber having a single core, the single core having multiple light propagating modes. Interferometric apparatus probes the single core multimode sensing fiber over a range of predetermined wavelengths and detects measurement interferometric data associated with the multiple light propagating modes of the single core for each predetermined wavelength in the range. Data processing circuitry processes the measurement interferometric data associated with the multiple light propagating modes of the single core to determine one or more shape-sensing parameters of the sensing fiber from which the shape of the fiber in three dimensions can be determined.

An apparatus, and related method, relates generally to a fiber-optic sensing system. In such a system, fiber-optic sensors are in a rosette or rosette-like pattern. An optical circulator is coupled to receive a light signal from a broadband light source, to provide the light signal to the fiber-optic sensors, and to receive a returned optical signal from the fiber-optic sensors. A spectral engine is coupled to the optical circulator to receive the returned optical signal and configured to provide an output signal.

The photonic integrated device comprises a substrate, a plurality of mechanical resonator structures on a surface of the substrate, exposed to receive sound waves from outside the device; a plurality of sensing optical waveguides, each sensing optical waveguide at least partly mechanically coupled to at least one of the mechanical resonator structures, or a sensing optical waveguide that is at least partly mechanically coupled to all of the mechanical resonator structures; an input optical waveguide on the surface of the substrate, coupled to the plurality of sensing optical waveguides or the single sensing optical waveguide, for supplying light to the plurality of sensing optical waveguides or the single sensing optical waveguide; at least one output optical waveguide on the surface of the substrate, coupled to the plurality of sensing optical waveguides or the single sensing optical waveguide, for collecting light from the plurality of sensing optical waveguides or the single sensing optical waveguide that has been affected by vibration of plurality of mechanical resonator structures.

Provided are embodiments for method and system for performing an integrated ice protection with prognostics and health management using fiber optic sensors. Embodiments can include reading a signal from each sensor of an array of sensors installed on a surface of a structure or equipment, wherein each sensor is a fiber optic sensor, and generating a map based on reading the signal from each sensor, wherein the map monitors a condition of the surface detected by each sensor. Embodiments can also include determining at least one of an abnormal condition or a failure based at least in part on reading the signal from each sensor; and performing at least one of adjusting power control for the structure or equipment or communicating the abnormal condition or failure of the structure or equipment.