A temperature sensor and temperature sensing system for sensing changes m temperature up to a predetermined temperature is disclosed. The temperature sensor includes a microstructured optical fiber where the micro-structured optical fiber includes a plurality of longitudinal channels extending along the microstructured optical fiber. The sensor also includes a fiber Bragg grating formed in the microstructured optical, fiber by generating a periodic modulation in the refractive index along a core region of the microstructured optical fiber. The fiber Bragg grating is operable to produce band reflection at a reflection wavelength that varies in accordance with changes in temperature at the core region of the optical fiber.

Embodiments of the current disclosure include small diameter single-mode optical fibers having gratings and methods of forming thereof. In some embodiments, methods of forming a small diameter single-mode optical fibers having gratings include providing an optical fiber having a core and cladding with a combined outer diameter of 100 μm to 125 μm and a coating having a thickness of less than or equal to 20 μm, wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer; and exposing the core, through the coating, to a pattern of ultraviolet radiation to form an optical grating within the core.

Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

A fiber grating device of low cost and arbitrary length is formed on a portion of a portion or the entirety of a highly elastic fiber optic core having a low Young's modulus of elasticity by causing elongation of the fiber optic core and forming or depositing a hard skin or cladding on the elongated fiber optic core. When the stress is then released, the hard skin or cladding buckles (including elastic or plastic deformation or both) to form wrinkles at the interface of the fiber optic core and the hard skin or cladding which are oriented circumferentially and highly uniform in height and spacing which can be varied at will by choice of materials, stretching, and thickness and composition of the cladding. Since the elastic elongation of the fiber optic core portion may be 200% or greater, an unprecedented measurement range is provided.

A technique is described for fabricating one or more optical devices in a carbon-coated optical fiber. A photosensitive optical fiber is provided having a hermetic carbon coating. Further provided is a laser having a beam output that is configured to inscribe one or more refractive index modulations into the optical fiber through the hermetic carbon layer while leaving the hermetic carbon layer intact. The laser is used to inscribe one or more optical devices into the optical fiber through the hermetic carbon layer.

Embodiments of the current disclosure include small diameter single-mode optical fibers having gratings and methods of forming thereof. In some embodiments, methods of forming a small diameter single-mode optical fibers having gratings include providing an optical fiber having a core and cladding with a combined outer diameter of 100 μm to 125 μm and a coating having a thickness of less than or equal to 20 μm, wherein the coating comprises one of: (i) a high-modulus coating layer surrounding the cladding region; or (ii) a low-modulus coating layer surrounding the cladding region and a high-modulus coating layer surrounding the low-modulus coating layer; and exposing the core, through the coating, to a pattern of ultraviolet radiation to form an optical grating within the core.

A method and a system for providing a low absorption Bragg grating along a grating region of an optical fiber are presented. The Bragg grating is written along the grating region by multiphoton absorption of ultrafast light pulses impinged on this grating region through a polymer coating of the optical fiber. The Bragg grating is then photobleached by propagating a photobleaching light beam along the optical fiber. The photobleaching light beam has optical parameters selected to reduce defects in the grating region induced by the writing of the Bragg grating in a substantially non-thermal regime.

A temperature sensor and temperature sensing system for sensing changes in temperature up to a predetermined temperature is disclosed. The temperature sensor includes a microstructured optical fiber where the microstructured optical fiber includes a plurality of longitudinal channels extending along the microstructured optical fiber. The sensor also includes a fiber Bragg grating formed in the microstructured optical, fiber by generating a periodic modulation in the refractive index along a core region of the microstructured optical fiber. The fiber Bragg grating is operable to produce band reflection at a reflection wavelength that varies in accordance with changes in temperature at the core region of the optical fiber.

A manufacturing device of an optical fiber grating to write a grating in a core of an optical fiber by irradiating the optical fiber with laser light includes: a fixing device that fixes the optical fiber to at least one of a first position located more on an upstream side and a second position located more on a downstream side in a conveyance direction of the optical fiber than a laser light irradiating position of the optical fiber in a case of writing the grating; and a feeder having a structure capable of linearly reciprocating in the conveyance direction and adapted to feed a predetermined length of the optical fiber in the conveyance direction in a case where a fixed state of the optical fiber by the fixing device is released.