An optical guidewire system employs an optical guidewire (10), an optical guidewire controller (12), a guide interface (13) and an optical connector (15). The optical guidewire (10) is for advancing a catheter (20) to a target region relative to a distal end of the optical guidewire (10), wherein the optical guidewire (10) includes one or more guidewire fiber cores (11) for generating an encoded optical signal (16) indicative of a shape of the optical guidewire (10). The optical guidewire controller (12) is responsive to the encoded optical signal (16) for reconstructing the shape of the optical guidewire (10). The guidewire interface (13) includes one or more interface fiber core(s) (14) optically coupled to the optical guidewire controller (12). The optical connector (15) facilitates a connection, disconnection and reconnection of the optical guidewire (10) to the guidewire interface (13) that enables a backloading the catheter (20) on the optical guidewire (10).

A distributed acoustic system (DAS) may comprise an interrogator and an umbilical line attached at one end to the interrogator, a downhole fiber attached to the umbilical line at the end opposite the interrogator. The interrogator may further include a proximal circulator, a distal circulator connected to the proximal circulator by a first fiber optic cable, and a second fiber optic cable connecting the proximal circulator and the distal circulator.

Methods for determining sensor channel location in distributed sensing of fiber-optic cables are disclosed. In one method, three or more Fiber Bragg-Gratings (FBGs) connected in series by a standard telecommunication fiber and interrogated using an input distributed fiber-optic sensing (DFOS) laser, where the input DFOS laser has a single wavelength. The input DFOS laser operates on a single wavelength that is different than the respective wavelengths of each of the three or more FBGs. The three or more FBGs are interrogated using an input broadband FBG laser. Each FBG reflects a wavelength of laser light that is proportional to the grating size, using an optical time domain reflectometer (OTDR) at the FBG wavelength, the distance to the particular FBG in the optical domain is computed and compared to the physical measurement of the FBG location. The sensor channel locations of the DFOS system are calibrated and constrained using this method.

An apparatuses relating generally to a test wafer, processing chambers, and method relating generally to monitoring or calibrating a processing chamber, are described. In one such an apparatus for a test wafer, there is a platform. An optical fiber with Fiber Bragg Grating sensors is located over the platform. A layer of material is located over the platform and over the optical fiber.

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.

An optical waveguide-transmitter apparatus, an ultrasonic transceiver apparatus, an ultrasonic imaging apparatus and an associated production method are disclosed. The optical waveguide-transmitter apparatus includes a substrate made of a semiconductor material; a carrier layer arranged on the substrate; and at least one transmitter-optical waveguide made of a semiconductor material with a refractive index greater than a refractive index of the carrier layer. At least one side of the waveguide is at least partially surrounded by the carrier layer. The waveguide is configured at an end facing toward the examination region for a decoupling of the light beams into the examination region for generating the ultrasonic waves in the examination region by way of the decoupled light beams for an optoacoustic imaging and/or has, on the end facing toward the examination region, an optical absorption layer for such a conversion of the light beams.

A curvature sensor includes a light source, a flexible light guide including cores, FBG sensors that are provided in the cores and constitute FBG sensor groups at predetermined positions along longitudinal axes of the cores. The curvature sensor includes a detector that detects an optical spectrum of light from the FBG sensors, and a processor that determines a bend position and a bend amount of the light guide. The FBG sensor groups include a first FBG sensor group and a second FBG sensor group next to it. FBG sensors in the first and second FBG sensor groups include gratings having first and second pitches. The first pitch is shorter than the second pitch and is closer to the second pitch than other pitches of gratings of FBG sensors that include gratings having pitches shorter than the second pitch.

The optical fiber sensing method of the present invention includes steps of: joining heat shrinkable tubes to two ends of a sensing segment of an optical fiber; coupling a fixing element on the heat shrinkable tube below the sensing segment; detachably connecting at least one floating element to the fixing element; placing the floating element into a fluid; and providing an input signal to the sensing segment and generating an output signal after the input signal is processed by the sensing segment, wherein the tensile force applied to the sensing segment would change with variation of the buoyant force upon the floating element, resulting in change of the output signal. Accordingly, the optical fiber sensing method has numerous advantages, including rapid on-site construction, recyclability of components and changeability of design parameters.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

In the examples provided herein, a polarization diversity receiver system includes a loop waveguide, and a two-dimensional grating coupler formed on the loop waveguide to couple light impinging on the grating coupler having a first polarization into the loop waveguide in a first direction, and to couple light having a second polarization orthogonal to the first polarization into the loop waveguide in a second direction. The system also includes a first output waveguide positioned near the loop waveguide in a first coupling region, a first distributed perturbation having a first resonant wavelength in the first coupling region to cause coupling of light at the first resonant wavelength between the loop waveguide and the first output waveguide, and a first photodetector to detect light propagating out of a first end and a second end of the first output waveguide.