A system configured to monitor a plurality of zones of an aircraft includes a line replaceable unit, a first interrogator, and a controller. The line replaceable unit includes first and second connectors in optical communication and an optical fiber. The optical fibers includes a first plurality of fiber Bragg gratings and a plurality of calibration fiber Bragg gratings in a pattern providing information related to a calibration value based upon a center wavelength of each of the first plurality of fiber Bragg gratings. The first interrogator is connected to the line replaceable unit at the first end of the optical fiber and is configured to provide a first optical signal and to receive a first optical response signal from the optical fiber. The controller is operatively connected to the first interrogator and is configured to determine the calibration value of the line replaceable unit.

According to one implementation an assembly is provided that facilitates a coupling of one or more light diffusing optical fibers to one or more light emitting diodes. According to one implementation the assembly includes a light emitting diode positioned inside a cavity of a frame that is equipped with means to directly or indirectly electrically couple the anode and cathode of the light emitting diode to a printed circuit board. A proximal end portion of the light diffusing optical fiber is supported inside a through opening of a lid positioned over a front side of the frame. The light diffusing optical fiber includes a core that is surround by a cladding. According to some implementations the proximal end of the light diffusing optical fiber is butt-coupled to the light emitting diode with there being no gap between the proximal end of the fiber and the light emitting side of the light emitting diode.

A fiber optic sensor device comprising an optical fiber with a multilayer coating on the optical fiber at least in a fiber section of the optical fiber. The multilayer coating comprises a chrome layer on the optical fiber, a metal layer such as a copper layer on the chrome layer and an indium or lead layer on the metal layer. The indium or lead layer having a thickness larger than thicknesses of the chrome and metal layers, preferably with a thickness about equal to the radius of the optical fiber.

An optical fiber with one or more microgratings is disclosed. Methods and apparatus are described for making an optical fiber with one or more microgratings. Methods and apparatus are described for an optical fiber with one or more microgratings Optical sensing methods and an optical sensing system effectively decouple strain range from the laser tuning range, permit the use of a smaller tuning range without sacrificing strain range, and compensate for ambiguity in phase measurements normally associated with smaller tuning ranges.

A method and system for using laser-induced structures to direct light to exit the bottom of a leaky mode device, and further to divide leaky mode light into multiple orders, and to implement one or more pulsing/strobing patterns such that a field of view is increased for a viewer, or the view zone is increased for a viewer. A leaky mode device may comprise a substrate, a surface acoustic wave (SAW) transducer, a waveguide having a higher refractive index than the substrate, an input region for input light, and laser induced structures such as grating. The SAW transducer may be positioned on a top surface of the substrate, and may be configured to emit a SAW wave to propagate across the substrate. The waveguide may be positioned below the SAW. The input wave region may be configured to couple light onto the waveguide. When light is coupled onto the waveguide, the refractive index may change such that the light in the waveguide exits the waveguide as leaky mode light and interacts with the laser-induced grating, which is below the waveguide. The laser-induced grating is configured to divide the leaky mode light into multiple orders, each bent at a different angle.

The ends of sensing and interrogating multicore fibers are brought into proximity for connection in a first orientation with one or more cores in the sensing fiber being paired up with corresponding one or more cores in the interrogating fiber. Optical interferometry is used to interrogate at least one core pair and to determine a first reflection value that represents a degree of alignment for the core pair in the first orientation. The relative position is adjusted between the ends of the fibers to a second orientation. Interferometry is used to interrogate the core pair and determine a second reflection value that represents a degree of alignment for the core pair in the second orientation. The first reflection value is compared with the second reflection value, and an aligned orientation is identified for connecting the sensing and interrogating fibers based on the comparison.

A method for forming a pressure sensor is provided wherein an optical fibre is provided, the optical fibre comprising a core, a cladding surrounding the core, and a birefringence structure for inducing birefringence in the core. The birefringence structure comprises first and second holes enclosed within the cladding and extending parallel to the core. A portion of the optical fibre comprising of the core and the birefringence structure is encased within a chamber, wherein the chamber is defined by a housing comprising a pressure transfer element for equalising pressure between the inside and the outside of the housing. An optical sensor is provided along the core of the optical fibre. The cladding is internally etched by flowing an etchant through the first and second holes along a length of the portion of optical fibre which comprises the optical sensor so as to increase the width of the first and second holes. The chamber is filled with a substantially non-compressible fluid. Consequently, the etched cladding is shaped so as to convert an external pressure provided by the non-compressible fluid within the chamber to an anisotropic stress in the optical sensor.

Coated optical fibers and uses of such fibers as sensors in high temperature and/or high pressure environments. The coated optical fiber has improved sensing properties at elevated pressure and/or temperature, such as enhanced acoustic sensitivity and/or a reduced loss in acoustic sensitivity. The use of the coated optical fibers in various sensing applications that require operation under elevated pressure and/or temperature, such as, acoustic sensors for various geological, security, military, aerospace, marine, and oil and gas applications are also provided.

An optical fiber including a plurality of embedded optical reflectors distributed periodically along the length of the fiber and a method of quantifying loss associated with an optical connector that is connected to optical fiber comprising a plurality of embedded optical reflectors distributed periodically along the length of the fiber. The method includes inserting an optical signal into the fiber through the optical connector; measuring a component of the optical signal reflected by at least one of the plurality of embedded optical reflectors, in which the component is received through the optical connector; calculating the difference in power level between the inserted and reflected signals; and quantifying, based on the calculated power level difference and the reflectivity of the embedded optical reflector, the loss associated with the optical connector.

A system includes at least one optical fiber having at least one FBG and a detection system. The optical fiber is configured to be coupled to a structure in at least one location. The location at which the optical fiber is to be coupled to the structure is different from a location at which the FBG is disposed. The detection system includes a light source configured to inject light into the optical fiber, a photodetector configured to detect a shift in a wavelength spectrum of light reflected by the FBG as a result of a time-varying strain induced at the at least one FBG, and a processor configured to detect a shear-horizontal guided stress wave propagating in said structure based on the shift in the wavelength spectrum detected by the photodetector induced by a longitudinal-type guided stress wave that is propagated along the optical fiber.