Improvements to gratings for use in waveguides and methods of producing them are described herein. Deep surface relief gratings (SRGs) may offer many advantages over conventional SRGs and Bragg gratings, an important one being a higher S-diffraction efficiency. In one embodiment, deep SRGs can be implemented as polymer surface relief gratings or evacuated Bragg gratings (EBGs). EBGs can be formed by first recording a holographic polymer dispersed liquid crystal (HPDLC) grating. Removing the liquid crystal from the cured grating provides a polymer surface relief grating. Polymer surface relief gratings have many applications including for use in waveguide-based displays.

A device includes a waveguide, an in-coupling element, and an out-coupling element coupled with the waveguide. The waveguide, the in-coupling element, and the out-coupling element are configured to deliver a plurality of portions of an image light to an eye-box of the device. At least one of the in-coupling element or the out-coupling element includes a polarization selective diffractive element. The polarization selective diffractive element includes a grating including a plurality of microstructures defining a plurality of grooves filled with a passive optically anisotropic material having a first effective refractive index along a groove direction of the grooves and a second effective refractive index along an in-plane direction perpendicular to the groove direction. One of the first effective refractive index or the second effective refractive index substantially matches with a refractive index of the microstructures.

An easy-to-fabricate and highly efficient single-mode optical fiber-to-single-mode optical waveguide coupler having relatively large horizontal and vertical alignment tolerances between the fiber and the waveguide coupler. The waveguide coupler also features ease of end-facet cleaving. The waveguide coupler can be used in ultra-broadband high coupling efficiency applications or other suitable applications. Single-mode on-chip waveguides incorporating such coupler(s) are also provided, as are methods of manufacturing the waveguide coupler and on-chip waveguide.

Apparatus and methods for remotely laying cable. A crawler comprises a propulsion means for moving the crawler along a surface. A controller stores the route followed by the crawler. As the crawler moves along the surface a cable is fed onto the surface. A fastener is then used to affix the cable to the surface.

A medical device that includes a carrier member, one or more operative components disposed in the carrier member, an optical fiber at least partly disposed in the carrier member, and at least one fiber Bragg grating (FBG) sensor array associated with the optical fiber and disposed in the carrier member. The carrier member includes an insertion end and side walls that contact the subject's body during positioning of the carrier member in the subject's body. The at least one FBG sensor array measures contact forces at one or both of the insertion end and along the side walls of the carrier member during positioning of the carrier member in the subject's body. A multi-core optical fiber configured for use in a medical device for positioning in a subject's body is also provided. A system and method for guiding positioning of a medical device in a subject's body is also provided.

The present disclosure relates to a passive fiber optic cabinet and a system for detecting a state of a door of a passive fiber optic cabinet. A passive fiber optic cabinet is provided, comprising: a housing; a door coupled to the housing and configured to be switchable between an open state and a closed state; a switch sensor module including a detection fiber Bragg grating (FBG) sensor and a stress applying mechanism corresponding to the detection FBG sensor, the stress applying mechanism configured to apply a stress o the detection FBG sensor, one of the detection FBG sensor and the stress applying mechanism being positioned at the door, and the other of the detection FBG sensor and the stress applying mechanism being positioned at the housing.

A solution is provided comprising boron nitride nanotubes (BNNTs) in a liquid solvent. An optical waveguide, such as an optical fiber, is contacted with the solution so as to form a layer of the solution supported on at least a portion of the optical waveguide. The liquid solvent is then removed from the layer of the solution supported on the optical waveguide in order to form a coating of the BNNTs on the optical waveguide. Further provided is a BNNT coated optical waveguide for use as a sensor.

Cable guides that support a fiber optic cable relative to a tube, hydrocarbon conveyance systems including the cable guides, and methods of acoustically probing an elongate region. The cable guides include a cable retention structure with a first retention region configured to align a first diffraction grating along a first sensing axis and a second retention region configured to align a second diffraction grating along a second sensing axis that is nonparallel to the first sensing axis. The tube defines a tubular conduit configured to convey a hydrocarbon. The hydrocarbon conveyance systems include a tube, a distributed acoustic sensor, and a cable guide. The methods include transmitting an initiated optical signal and receiving a reflected optical signal that includes reflected portions that are reflected by a first diffraction grating and a second diffraction grating. The methods further include analyzing the reflected optical signal to detect an applied mechanical strain.

A WDM1r combiner for a PON. The output end of an input waveguide is connected to the input end of a first grating filter, the output end of the first grating filter is connected to the input ends of a first mode filter, a second grating filter, a second mode filter, a connecting waveguide, a third grating filter, a third mode filter, and a fourth grating filter in sequence, and the output end of the fourth grating filter is connected to an output waveguide. The function of the WDM1r combiner for a PON is achieved in the form of cascaded grating filters; different central wavelengths and bandwidths of four channels are obtained by optimizing a grating structure; an on-chip WDM1r combiner which is low in insertion loss and crosstalk and has flat-top response is obtained; the combiner has the advantages of being simple in structure, simple in process, excellent in performance, etc.

A laser interferometer that includes a light source configured to emit laser light, an optical divider configured to divide the laser light into a first optical path and a second optical path, an optical modulator being provided on the first optical path or the second optical path, including an oscillator that oscillates when a current is applied, and being configured to modulate the laser light by using the oscillator, a photoreceptor configured to receive the laser light and output a photoreception signal, the laser light being reflected by an object to be measured that is provided on the first optical path or the second optical path, and a demodulation circuit configured to demodulate, from the photoreception signal, a Doppler signal derived from the object to be measured, based on a reference signal and a modulation signal derived from the optical modulator, wherein Iq/f≤1×10.sup.−7 is satisfied, where an amplitude value of the current applied to the oscillator that is oscillating is Iq [A] and an oscillation frequency of the oscillator is f [Hz].