Abstract: A novel method based on sequential writing for fabricating of advanced fiber Bragg gratings is disclosed. As opposed to already presented sequential methods, this scheme uses a continuous wave UV laser source and allows for a very precise control and repetitively of the formation of the gratings. Furthermore, one can use high average irradiances without destroying the fiber, resulting in a dramatical shortening of fabricating times for complex gratings.

Abstract: A novel method and apparatus for fabrication of blazed and slanted fiber Bragg gratings is disclosed. The method comprises the step of simultaneously exposing the fiber with two mutually coherent light beams so as to create an interference pattern along a longitudinal axis of the fiber, wherein each one of said beams is brought into a line focus, which coincides with the core of the fiber. Further, the plane comprising the beams is rotated to provide a second angle relative to the fiber direction, said rotation giving rise to a blazing angle of the photo-induced grating elements.

Abstract: A novel method based on sequential writing for fabricating of advanced fiber Bragg gratings is disclosed. As opposed to already presented sequential methods, this scheme uses a continuous wave UV laser source and allows for a very precise control and repetitively of the formation of the gratings. Furthermore, one can use high average irradiances without destroying the fiber, resulting in a dramatical shortening of fabricating times for complex gratings.

Abstract: The invention relates to the coupling of light to and from an optical waveguide, such as an optical fibre. Light of a specific wavelength is deflected out from the fibre, or into the fibre, in a substantially transverse direction with respect to the propagation direction of light in the waveguide, by a deflector 16 arranged in the fibre core 10. Wavelength selectivity of the deflector 16 is provided by a Bragg grating means located in the fibre core 10. The deflected light is collimated, or converged towards a focus, by an interface 15 between a cladding 11, having one index of refraction, and an outer medium 12, having another index of refraction. The ratio between the radius of the cladding 11 and the radius of the core 10 made sufficiently small for the collimating, or converging, effect to appear.

Abstract: A method of establishing transmission of light through a chirped Bragg-reflector, a method of analyzing the power spectrum of a light signal using a chirped Bragg-reflector, and an arrangement for analyzing the power spectrum of a light signal. The Bragg-reflector reflects, in an unperturbed state, essentially all incident light within a predefined wavelength range. The methods include the steps of directing the light to be analyzed into an input end of a light guiding structure, such as an optical fiber, which light guiding structure is provided with a Bragg-reflector, and sending an acoustic pulse along the light guiding structure, thereby effectively lowering the reflectance of the Bragg-reflector for a certain wavelength at a certain time. By monitoring the light thus transmitted through the Bragg-reflector, a power spectrum analysis of the incident light is obtained.

Abstract: The invention is a spectrally selective optical coupler with a new geometry and a new principle of action. An optical coupler according to the invention includes an optical waveguide and an external resonator. In the waveguide, there is provided a deflector that is operative to deflect light of a predetermined wavelength into the external resonator. Coupling is enhanced by the deflected wavelength being resonant in the external resonator.

Abstract: A method of establishing transmission of light through a chirped Bragg-reflector, a method of analyzing the power spectrum of a light signal using a chirped Bragg-reflector, and an arrangement for analyzing the power spectrum of a light signal. The Bragg-reflector reflects, in an unperturbed state, essentially all incident light within a predefined wavelength range. The methods include the steps of directing the light to be analyzed into an input end of a light-guiding structure, such as an optical fiber, which light-guiding structure is provided with a Bragg-reflector, and sending an acoustic pulse along the light-guiding structure, thereby effectively lowering the reflectance of the Bragg-reflector for a certain wavelength at a certain time. By monitoring the light thus transmitted through the Bragg-reflector, a power spectrum analysis of the incident light is obtained.

Abstract: There is shown an arrangement for detecting elastic deformation of a tool shaft carried by a machine tool and, in turn, carrying a cutting bit. An optical fibre section is mounted in or on the shaft at a distance from its neutral bending line in the longitudinal direction of said shaft. The optical fibre section, which follows the elastic deformation of the shaft, extends parallel with and at a constant distance fro the neutral bending axis of said shaft, so that elongation of the fibre section forms a measurement of bending of the shaft in an axial plane that includes the optical fibre section. The optical fibre section has at least two longitudinally spaced partial reflection means and means are connected to the optical fibre section to determine interferometrically a change in distance between the partial reflection means in the optical fibre section, wherein the change in distance forms a measurement of shaft curvature between the two partial reflection means.

Abstract: Apparatus for determining the curvature of an elongated channel, such as a drill hole in rock for instance, wherein the apparatus includes a probe (1) which may be constructed for movement through the channel and to assume the curvature of the channel at the different positions into which the probe is moved along the channel, wherein the probe (1) includes means (3, 31, 10) for sensing the curvature of the probe, and thus also the curvature of the channel, between at least two longitudinally spaced positions (A, B) on the probe (1), and wherein the apparatus can be connected to means (10) for determining the extension of the channel by registering curvature of the probe, for instance in different positions of the probe along the channel.