A temperature monitoring apparatus configured to monitor a temperature of a portion of a vehicle's electrical energy distribution network is disclosed. The apparatus includes a first optical fibre including one or more temperature sensing sections, each temperature sensing section being for thermal contact with a portion of a vehicle's electrical energy distribution network. Each temperature sensing section is arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section. The apparatus is arranged to determine a temperature of the portion of the vehicle's electrical energy distribution network based on one or more of the output optical signals in use.

Disclosed is an optical fiber probe for an optical treatment including a core, to which incident light is guided, a cladding disposed to surround the core, a side surface divergence part connected to the core and configured to diverge the incident light guided to the core to a side surface of a cylindrical column, a diffusion layer disposed to surround the side surface divergence part, a distal end divergence part connected to the side surface divergence part, having a cylindrical shape, and configured to diverge the incident light guided to the side surface divergence part to the outside, and a coating layer disposed to surround the cladding and the diffusion layer and configured to seal the cladding and the diffusion layer, wherein the refractive index of the cladding is lower than the refractive index of the core, the refractive index of the diffusion layer is higher than the refractive index of the core, and the refractive index of the coating layer is higher than the refractive indices of the cladding and the diffusion layer.

An optical device with photon flipping for converting an incident light flux into a practically monochromatic light beam, the device including a cladding area including a photon crystal microstructure, the photon crystal microstructure having an allowed spectral band and a spectral band gap; a flipping area including a flipping fluorescent dye which has a spectral band for absorbing fluorescence, which covers at least part of the allowed spectral band, and a spectral band for emitting fluorescence, which covers at least part of the spectral band gap of the photon crystal microstructure; a central area arranged to enable propagation of a monochromatic light beam having a wavelength in the spectral band gap, the central area being surrounded by the photon crystal microstructure; the core area having a thickness which is less than or equal to five times the wavelength of the maximum fluorescence emission of the flipping fluorescent dye.

A high backscattering optical fiber comprising a perturbed segment in which the perturbed segment reflects a relative power such that the optical fiber has an effective index of n.sub.eff, a numerical aperture of NA, a scatter of R.sub.p.fwdarw.r.sup.(fiber) that varies axially along the optical fiber, a total transmission loss of ?.sub.fiber, an in-band range greater than one nanometer (1 nm), and a figure of merit (FOM) in the in-band range. The FOM being defined as: $FOM=\frac{R_{p.fwdarw.r}^{\left(\mathrm{fiber}\right)}}{{{?}_{\mathrm{fiber}}\left(\frac{\mathrm{NA}}{2n_{\mathrm{eff}}}\right)}^2}.$

The present application is directed in various illustrative embodiments to an optical waveguide, an optical waveguide system with such an optical waveguide, a light energy storage structure, light confining structures, a light energy storage system and an energy storage and/or conversion system with such an optical waveguide system. In an aspect, an optical waveguide is provided, comprising an optical fiber with a fiber core and an optical active cladding structure over at least a portion of the fiber core at a first end of the optical waveguide, wherein the optical active cladding structure comprises a Bragg mirror stacking having a high transmittance in a first wavelength region and a high reflectivity in a second wavelength region of wavelengths longer than wavelengths in the first wavelength region, and a wavelength conversion coating over the fiber core of the optical fiber. The wavelength conversion coating is configured to convert radiation with wavelengths in the first wavelength region into radiation with wavelengths in the second wavelength region and the Bragg mirror stacking is disposed over the wavelength conversion coating.

Disclosed is an optical fiber including a plasmonic optical filter with a closed curved shape provided at, at least portion thereof. A method of manufacturing the plasmonic optical filter includes a step of exposing a core, a step of forming a thin metal film on the core through physical vapor deposition while rotating the core in a circumferential direction after changing a rotation axis of the core, and a step of patterning nanopatterns on the cylinder-shaped thin metal film using focused ion beam technique assisted with endpoint detection method. Due to such constitutions, an active area to generate an optical signal for optical sensor can be increased.

A field inverting optical waveguide is disclosed. The waveguide is configured to convey electromagnetic radiation from an ingress end to an egress end along an optical path. The waveguide includes an optically flat input surface disposed at the waveguide ingress end, and an exit surface disposed substantially opposite the input surface at the waveguide egress end. The exit surface includes an array of prisms projecting outward from or inward to the exit surface. The input surface and the exit surface are arranged substantially orthogonally to the optical path.

A quantum device for interfacing Lanthanide ions with optical fields or microwave fields or both. The device includes waveguides or resonators or both for optical fields or microwave fields or for both. The device includes at least one surface to which a single customized Lanthanide molecular complex, or an ensemble, layer, multilayer or crystal of such, are attached or bonded. This places the Lanthanide ions within the optical or microwave fields or both. The ability to customize the molecular structure around each Lanthanide ion, and to control their orientation and position and nano-environment in general, enables minimizing the host lattice effects and non-radiative loss channels for each ion, and increasing their homogeneity. Accordingly, the advantages of the present invention include reduced inhomogeneities, narrower linewidths, extended fluorescence and coherence times, and higher operation temperatures. Devices which benefit from the present invention include lasers, amplifiers, sensors, quantum memories, repeaters and quantum information processing devices at optical fields, microwave fields, or both, including bi-directional optical-microwave convertors.

An integrated fiber-ferrule useable as an optical coupling element includes a core directly contacting a cladding layer that has a lower index of refraction than that of the core, without an intervening adhesive. The cladding layer outer diameter is at least 100 times greater than that of the core, and matches an outer diameter of a standard ferrule. The integrated fiber-ferrule may be produced by drawing a glass preform into a cane, cutting the cane into sections, and shaping end faces of the cut sections (e.g., using a laser). To form a fiber optic assembly, a front end of an optical fiber core may be fusion spliced to a rear end of the core of the integrated fiber-ferrule. Use of an integrated fiber-ferrule permits reduction of core to fiber eccentricity, and reduction of connector insertion losses.

A thermal microring optical sensor is configured such that a portion of the optical resonator and its associated waveguide are encased within a cladding structure to minimize scattering losses along the waveguide and also provide improved evanescent coupling efficiency between the waveguide and the resonator. Functioning as a thermal sensor, incoming radiation modifies the temperature of the resonator, which changes its resonant frequency and, as a result, the percentage of light that it evanescently couples from the waveguide. The cladding structure also functions as a mechanical support for the resonator disk, eliminating the need for a pedestal to suspend the disk above the support substrate. Thermally-induced buckling of the optical waveguide is also reduced by encasing the susceptible portion of the waveguiding within the cladding structure.