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.

The field of integrated health monitoring using Bragg grating optical fibre sensors including a sensor and methods for locating and installing this sensor on a support. The Bragg grating optical fibre sensor includes an optical fibre wherein at least one set of patterns forming a Bragg grating is written, the optical fibre further including a set of microstructures in the vicinity of each Bragg grating, the microstructures being separate from the patterns forming the Bragg grating, each microstructure being capable of scattering a portion of a light beam within a predetermined range of scattering wavelengths.

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 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. Providing the optical sensor comprises optically inducing stress in the core so that the optical sensor exhibits intrinsic birefringence. The chamber is filled with a substantially non-compressible fluid. Consequently, the birefringence structure 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.

A polarization-independent orbital angular momentum modulator based on a chiral fiber grating, a method for manufacturing the same, and an orbital angular momentum beam generator. The orbital angular momentum modulator includes an optical fiber body having a spiral fiber structure, and the spiral fiber structure has a long-period optical fiber grating effect. The optical fiber body has a periodic spiral refractive index modulation in an axial direction. A period of the spiral refractive index modulation has a magnitude of hundreds of microns, and the spiral refractive index modulation is distributed in an axial direction, a radial direction, and an angular direction of the optical fiber body, and configured to excite a spiral phase to generate an orbital angular momentum beam

A reactor temperature measurement system includes a Fiber Bragg Grating sensor array arranged in a body of the reactor for monitoring temperatures at multiple positions in an axial direction of the body to obtain temperature sensing optical signals; and a fiber grating demodulator, connected to the Fiber Bragg Grating sensor array, and used to demodulate the temperature sensing optical signals. A method for preparing a Fiber Bragg Grating includes preparing a Fiber Bragg Grating by using a single-mode fiber and annealing the Fiber Bragg Grating, which includes heating the Fiber Bragg Grating to a temperature above 400° C. and maintaining for 100 to 200 hours.

The present disclosure provides a preparation method of an optical fiber device having a polymer micronano structure integrated in an optical fiber, the method comprising: welding a hollow optical fiber so that the hollow optical fiber is welded between two solid optical fibers, ablating the welded hollow optical fiber utilizing a femtosecond laser ablation technology so that a channel vertical to an inner wall is ablated on the hollow optical fiber, filling a colorless and transparent liquid photoresist material inside the hollow optical fiber which has been ablated so that the inside of the hollow optical fiber is filled with the photoresist material, and polymerizing on the photoresist material inside the hollow optical fiber utilizing a femtosecond laser two-photon polymerization technology.

An optical fiber filter includes a fiber core, inner cladding, and outer cladding. A refractive index of the fiber core, a refractive index of the inner cladding, and a refractive index of the outer cladding progressively decrease in sequence. The fiber core is configured to transmit at least two mutually different first optical signal modes, the inner cladding is configured to transmit at least two mutually different second optical signal modes, and at least one fiber grating is etched on the fiber core. At least part of optical power of a target first optical signal mode is coupled to only a target second optical signal mode at the fiber grating. The target first optical signal mode is one of the at least two first optical signal modes, and the target second optical signal mode is one of the at least two second optical signal modes.

A polarization-independent orbital angular momentum modulator based on a chiral fiber grating, a method for manufacturing the same, and an orbital angular momentum beam generator. The orbital angular momentum modulator includes an optical fiber body having a spiral fiber structure, and the spiral fiber structure has a long-period optical fiber grating effect. The optical fiber body has a periodic spiral refractive index modulation in an axial direction. A period of the spiral refractive index modulation has a magnitude of hundreds of microns, and the spiral refractive index modulation is distributed in an axial direction, a radial direction, and an angular direction of the optical fiber body, and configured to excite a spiral phase to generate an orbital angular momentum beam.

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 three-dimensional Bragg grating may include a single colloidal crystal that includes a plurality of repeated layers of material having different refractive indexes. A sample cell for producing a volume Bragg grating may include an internal shape that forms at least one capillary cell having a flat surface and rounded edges. A method of producing a three-dimensional Bragg grating may include: suspending insoluble particles in a host fluid to form a suspension; and exposing the suspension to a sustained microgravity environment.