An optical fiber cladding optical filter includes an elongated capillary tube including an inner surface positioned surrounding an elongated optical fiber proximate or adjacent an exterior surface of the optical fiber and an outer surface positioned spaced from the exterior surface of the optical fiber. A grating formed on the outer surface of the elongated capillary tube aids in suppressing evanescent laser light that exits the optical fiber transverse to a longitudinal axis of the optical fiber. The elongated optical fiber and surrounding elongated capillary tube can include one or more curves along a length thereof to aid in the removal of one or more higher order laser modes as evanescent laser light that exits the optical fiber. The one or more curves can be received in a container to prevent or avoid evanescent laser exiting the optical fiber from propagating into an ambient environment.

A wavelength division multiplexer is disclosed. The wavelength division multiplexer may include an input waveguide, in which a plurality of Bragg gratings for separating multiplexed optical signals into respective optical signals are provided, and a plurality of output waveguides connected to the input waveguide and configured to receive the optical signals separated by the plurality of Bragg gratings. The plurality of Bragg gratings may include a first Bragg grating including first protrusions each having a first width, and a second Bragg grating including second protrusions each having a second width larger than the first width. Each of the first and second protrusions may include a curved side surface, to which a corresponding one of the optical signals is incident.

A communication apparatus includes an optical fiber along which radiation can be transmitted; an optical fiber grating formed within the optical fiber, the optical fiber grating having a structure, and configured to reflect radiation at a particular wavelength; and an instrument coupled to the grating and configured to controllably modify the structure of the grating, thereby changing the wavelength at which the grating reflects radiation. A communication system including the communication apparatus is also described, along with a method of communicating a signal.

An object of the present disclosure is to provide an optical side input/output circuit for allowing light for being input into or output from a side surface of an optical fiber with high efficiency.

The present disclosure is an optical side input/output circuit including: a tap unit in which a tap waveguide is formed for allowing light for propagation through a core of an optical fiber for being input into or output from a side surface of the optical fiber; and a refractive index matching unit, having a refractive index higher than a refractive index of the tap waveguide, on the side surface of the optical fiber where the light is allowed for being input or output by the tap waveguide.

A photonic sensor system includes: a photodetector; a signal processor coupled to the photodetector; and a sensor structure configured to provide fluid-response selectivity, spatially distribute light, and to receive light from a light source and convey light to the photodetector. The sensor structure includes a plurality of fluid sensitive interferometric nanostructure layers manufactured on a substrate; wherein the plurality of fluid sensitive interferometric nanostructure layers includes alternating high and low porosity layers.

Application of non-uniform strain to discrete segments of a fiber grating mechanically changes the structure type of the associated device, e.g., the refractive index perturbation profile of the fiber grating is changed from uniform to phase shifted superstructured, or from chirped to superstructured. The strain may be applied with one or more deformable corrugated slides which are bonded to the fiber grating between the discrete segments. The applied strain changes the local period of fiber grating. Complex changes may be achieved via variations of corrugated slide dimensions. An LPFG may be provided with bare fiber by applying periodically longitudinal axial strain to fiber at multiple discrete segments on the fiber.

Provided are an LPFG and an optical transmission system in which a mode conversion amount does not depend on a polarization state and an electric field distribution. The LPFG according to the present invention includes cavity rows (25-1 and 25-2) of cavities 15 periodically arranged in a core region 11 of the few-mode fiber 10 at a position away from a central axis z of the core region 11 in parallel with the central axis z. Each of the cavity rows (25-1 and 25-2) is located at a different position in a longitudinal direction of the few-mode fiber 10 (where the position in a z direction is different), and the cavity rows (25-1 and 25-2) are located at positions shifted by 90 on a cross section of the core region 11 with the center of the cross section of the core region 11 (the intersection of an x-axis and a y-axis) as an origin.

Optical arrangements for processing a workpiece include a fiber laser arrangement for emitting laser radiation, a fiber arrangement directly coupled to the fiber laser arrangement and configured to guide the laser radiation in a direction to the workpiece to be processed, the fiber arrangement including a transport fiber having a fiber core and at least one fiber cladding surrounding the fiber core, and at least one coupling device for coupling a portion of the laser radiation guided in the fiber arrangement into at least one fiber cladding of the transport fiber. The coupling device has a spectral bandwidth of at least the same magnitude as a spectral bandwidth of the laser radiation. The fiber laser arrangement is configured to change a beam profile of the guided laser radiation to shift the spectral bandwidth of the laser radiation relative to the spectral bandwidth of the coupling device.

A communication apparatus includes an optical fiber along which radiation can be transmitted; an optical fiber grating formed within the optical fiber, the optical fiber grating having a structure, and configured to reflect radiation at a particular wavelength; and an instrument coupled to the grating and configured to controllably modify the structure of the grating, thereby changing the wavelength at which the grating reflects radiation. A communication system including the communication apparatus is also described, along with a method of communicating a signal.

The disclosed embodiments provide systems and methods for mitigating lensing and scattering as an optical fiber is being inscribed with a grating. The disclosed systems and methods mitigate the lensing phenomenon by surrounding an optical fiber with an index-matching material that is held in a vessel with an integrated interferometer (e.g., phase mask, etc.). The index-matching material has a refractive index that is sufficient to reduce intensity variations of the actinic radiation within the optical fiber. Some embodiments of the system include different vessels for holding the index-matching material, with the vessel having an interferometer integrated into the vessel. These vessels permit the optical fiber to be surrounded by the index-matching material while the gratings are written to the optical fiber.