Abstract: A section of tapered optical fiber is provided to protect optical components from catastrophic damage that may propagate within an optical route. The tapered section functions as a fuse to arrest the propagation of optical power induced damage by leaking optical power from a waveguiding region below a threshold, below which further propagation of damage is not supported.

Abstract: An athermalized optical fiber component assembly including a limiting member, a mounting structure attached to the limiting member, a temperature compensating substrate attached to the mounting structure, and an optical fiber component mounted on the temperature compensating substrate. The movement of the temperature compensating substrate as a function of temperature is constrained by the limiting member. Also, a method for manufacturing an athermalized optical fiber component assembly.

Abstract: Optical device and method for protecting an optical communications route A section of tapered optical fiber is provided to protect optical components from catastrophic damage that may propagate within an optical route. The tapered section functions as a fuse to arrest the propagation of optical power induced damage by leaking optical power from a waveguiding region to below a threshold, below which further propagation of damage is not supported.

Abstract: An apodised refractive index grating is recorded in a photosensitive optical fibre by forming first and second component interference patterns with different pitches, that are recorded in the grating such as to result in apodisation. The component patterns (16, 17) are spatially in phase in a central region and move progressively out of phase towards the ends of the patterns. The patterns may be recorded sequentially or concurrently. The fibre may be stretched one or cyclically.

Abstract: An apodised refractive index grating is recorded in a photosensitive optical fiber by forming first and second component interference patterns with different pitches, that are recorded in the grating such as to result in apodisation. The component patterns are spatially in phase in a central region and move progressively out of phase towards the ends of the patterns. The patterns may be recorded sequentially or concurrently. The fiber may be stretched once or cylically.

Abstract: An apodised refractive index grating is recorded in a photosensitive optical fiber by forming first and second component interference patterns with different pitches, that are recorded in the grating such as to result in apodisation. The component patterns are spatially in phase in a central region and move progressively out of phase towards the ends of the patterns. The patterns may be recorded sequentially or concurrently. The fiber may be stretched once or cylically.

Abstract: A device for recording a refractive index pattern in a photosensitive optical fiber includes a rotary disc formed with a phase mask in a circular pattern, which is rotated by an axis. The phase mask is illuminated with laser light in a region so that a moving interference pattern is formed. The optical fiber is moved along a path in synchronism with the moving interference pattern so that the pattern becomes recorded in the fiber. The pattern can be formed continuously over long fiber lengths, e.g., of the order of one meter.

Abstract: It has been demonstrated that B containing glasses are sensitive to radiation in the band 225-275 nm and, therefore, B2O3 glasses are particularly adapted to receive refractive index modulation, e.g., to make reflection gratings. Glasses containing SiO2 and B2O3 are particularly suitable when the grating is to be localized in the cladding of a fiber. Glasses containing SiO2, GeO2, and B2O3 are suitable when the grating is in the path region of a waveguide, e.g., in the core of a fiber.

Abstract: A multiple band pass optical filter comprises an interferometer, such as a Michelson interferometer, with de-tuned reflective Bragg gratings 8, 9 that produce multiple, separate, substantially equal reflectivity pass bands for light passing from the interferometer's input port P1 to output port P2.

Abstract: An optical fibre in a core and a cladding that includes an inner cladding region with a refractive index that is photosensitive to UV light, surrounded by a non-photosensitive outer cladding region. Refractive index gratings can be written into the cladding region. Also, the refractive index of the inner region can be altered by exposure to UV light to achieve mode matching at a splice between fibres with different core diameters. An optical fibre laser is disclosed with integral refractive index gratings in the cladding of a fibre with an optically active core.

Abstract: Boron containing glasses are sensitive to radiation in the band 225-275 nm and therefore, B.sub.2 O.sub.3 glasses are particularly adapted to receive refractive index modulation, e.g., to make reflection gratings. Glasses containing SiO.sub.2 and B.sub.2 O.sub.3 are particularly suitable when the grating is to be localized in the cladding of a fibre. Glasses containing SiO.sub.2, GeO.sub.2 and B.sub.2 O.sub.3 are suitable when the grating is in the path region of a waveguide, e.g., in the core of a fibre.

Abstract: An optical modulator includes a bi-moded fiber for supporting first and second different optical transmission modes, coupled between input and output single mode fibers. The two modes in the bi-moded fiber interfere and the intensity of the radiation that passes to the single mode output fiber is a function of the relative phases of the first and second modes. The bi-moded fiber is electrically poled and is provided with modulating electrodes. When a modulating voltage from a modulating source is applied to the electrodes, the refractive index of the waveguide for the first transmission mode is altered relative to the refractive index of the waveguide for the second mode such as to change the phase difference between the modes at the entrance to the output fiber so as to control the intensity of optical radiation that passes through the output fiber.

Abstract: It has been demonstrated that B containing glasses are sensitive to radiation in the band 225-275 nm and, therefore, B.sub.2 O.sub.3 glasses are particularly adapted to receive refractive index modulation, e.g., to make reflection gratings. Glasses containing SiO.sub.2 and B.sub.2 O.sub.3 are particularly suitable when the grating is to be localized in the cladding of a fiber. Glasses containing SiO.sub.2, GeO.sub.2, and B.sub.2 O.sub.3 are suitable when the grating is in the path region of a waveguide, e.g., in the core of a fiber.

Abstract: An optical fibre is formed with longitudinal recesses (11, 12) which extend toward its core (3) through cladding region (2). The recesses receive electrode structures (20a, b) made of glass, which include tongues (23a, b) that fit into the recesses, on which metal electrode strips (a, b) are formed. A potential difference applied between the strips (a, b) can induce electro-optic effects in the core.

Abstract: A resonant laser device including first and second reflectors defining an optical cavity with given optical resonance characteristics. The laser device including a laser active material in a first optical fiber disposed between the reflectors in the cavity and a second photosensitive optical fiber coupled to the cavity. One of the reflector being a refractive index grating formed in the second fiber such that the laser operates with a selected predetermined wavelength and the laser being tuned to a different wavelength by exposing the second fiber to a second spatially periodic pattern of optical radiation such that the second pattern becomes recorded in the second optical fiber.

Abstract: A laser having two feedback elements at least one which is wavelength selective, is provided with a demountable optical connector located between the gain medium of the laser and the wavelength selective feedback element. An optical waveguide is utilized to direct optical radiation between the demountable optical connector and the wavelength selective feedback element. The demountable optical connector, for example, a mechanical fibre connector allows the wavelength selective feedback element, for example, a fibre grating, to be exchanged cheaply, simply and quickly, and thus allows the wavelength of operation of the laser to be altered.

Abstract: A method of assembling a package including a photosensitively configured optical device providing a window positioned to allow optical frequency electromagnetic radiation from an external source to impinge on a photosensitive part of the optical device. In one embodiment a packaged intermediate product is fabricated, which may subsequently be formed into an external cavity semiconductor laser having certain specified characteristics, by writing a grating into a photosensitive fiber. Use of a window allows the characteristics of the laser to be defined after packaging so that, firstly a large stock of external cavity lasers having all possible characteristics need not be held, and secondly so that the reflectivity of the grating need be chosen only once the degree of coupling between the fiber and the laser diode has been established, thus enhancing the performance of the external cavity laser.

Abstract: A filter has a preselected attenuation/wavelength characteristic, in which spatially separated parts of the filter attenuate different wavelengths. The spatially-separated parts have different attenuation characteristics to attenuate different wavelengths in a predetermined manner to provide a selected attenuation/wavelength characteristic. In one arrangement an interference type filter includes a grating, the pitch of which varies spatially. In one instance, the structure to determine the proportion of radiation subject to interference includes a grating of spatially-varying effectiveness, but alternatively it may include an attenuation filter, the attenuation effect of the attenuation layer varying spatially. In another arrangement, the filter may include structure to separate received radiation into a spatially-disposed spectrum, and to attenuate different parts of the spatially-disposed spectrum in such a manner as to provide the selected attenuation/wavelength characteristic.

Abstract: The present invention is based on the use of a plurality of gratings recorded in an optical waveguide, the gratings having different Bragg wavelengths selected to store individual bits of data. The invention has particular application to optical fiber communications networks.

Abstract: An optical fibre is fixed between a clamp and a piezo-electric translation stage. An argon ion laser emitting at 514.5 nm is used to write Bragg gratings in the fibre. A different longitudinal stress is applied to the fibre before optically writing each Bragg grating. The fibre when unstressed will have a Bragg grating of different peak reflectivity corresponding to the number of different applied stresses.