Plessey Overseas Limited

Aston University

The Plessey Company Plc

Aston Photonic Technologies Limited

British Aerospace Public Limited Company

Bookham Technology Limited

Ian Bennion

Lin Zhang

Clive Trundle

Jack Brettle

Xuewen Shu

Christopher J Groves-Kirkby

Rosemary Cush

Yu Liu

Roger William Whatmore

Catherine Anne Sugden

Douglas C Reid

William John Stewart

Sergei Turitsyn

Martin J Goodwin

John A R Williams

Bashir Aliyu Labbo Gwandu

Christopher J Groves-Kirby

Filip Floreani

Thomas David Paul Allsop

Donghui Zhao

Robert Glenn

John Williams

Christopher J Rowe

Timothy Earthrowl-Gould

Christopher Groves-Kirkby

A Gires-Tournois etalon (GTE) () comprising an optical fiber () in which a primary chirped fiber Bragg grating (FBG) () is provided, an RF signal generator (), a piezoelectric transducer (), and a glass horn (), for coupling an acoustic wave (26) into the fiber (). The acoustic wave (26) causes a periodic compression within the fiber (), which induces a low frequency periodic refractive index modulation within the grating section () of the fiber (). This causes two side frequency components to be generated for each high-frequency component of the FBG (). Two secondary grating are thus excited, having the same spectral bandwidth as the FBG (), but a lower reflectivity and different central wavelengths. The free spectral range of the GTE () can be adjusted by varying the frequency of the acoustic wave (). The reflectivity of the excited secondary gratings can be adjusted by adjusting the amplitude of the acoustic wave ().

Gires-Tournois etalons and dispersion compensators

Surface profiling apparatus () according to one embodiment comprises three long period gratings (LPGs) () fabricated in progressive three layered (PTL) fibre (18) and embedded within a deformable carrier member () comprising a skeleton () provided between two sheets of flexible rubber skin (). The LPGs () are illuminated by three wavelength modulated, narrow bandwidth optical signals, each having a different wavelength and modulation frequency. A photodetector () connected to three lock-in amplifiers () measures the amplitudes of the first and second harmonic frequency components of the photodetector output signal corresponding to each LPG (). Similar surface profiling apparatus () forms the basis for respiratory function monitoring apparatus (100) in which five LPGs are provided within each of four PTL fibres (104, 106, 108, 110) and embedded in four carrier members (40) attached to a garment (114) to be worn by a subject.

Optical waveguide based surface profiling apparatus

A regenerated optical waveguide is fabricated by hydrogenating an optical waveguide () and exposing a grating section () to a UV laser beam interference fringe pattern () to form a Type I grating. The grating section () is exposed for a second period to erase the Type I grating, and then a third period to cause a regenerated optical waveguide grating to form. The resonant wavelength increases during the third period from being substantially the same as the final wavelength of the Type I grating.

Methods of fabricating a regenerated optical waveguide grating

In the present invention an optical waveguide grating sensing device for a dual-parameter optical waveguide grating sensor includes a first optical waveguide grating of a first resonant wavelength provided in a first section of an optical waveguide and a second optical waveguide grating of a second resonant wavelength provided in a second of an optical waveguide. The first and second gratings have different coefficients of rate of change of wavelength as a function of temperature and have substantially the same coefficient of rate of change of wavelength as a function of stain.

Dual-parameter optical waveguide grating sensing device and sensor

Optical pulse transmission lines

A strain sensor comprises an optical waveguide having a plurality of reflecting structure (Bragg grating) along its length. Each structure reflects light at a different characteristic wavelength (&lgr; to &lgr; ) which changes in dependence on a change of physical length of at least part of the reflecting structure. The reflectivity of reflecting structures which reflect at characteristic wavelengths which are adjacent to each other (&lgr; and &lgr; or &lgr; and &lgr; ) are configured to be different such that the intensity of light reflected from adjacent structures can be used to discriminate between them.

Strain sensing

Apparatus for sensing temperature and/or strain in an object includes a broadband light source (1), connector means (2) in the form of an optical circulator or an optical coupler to which at least two substantially identical optical fiber Bragg gratings (4, 5) are connected. Grating (4) receives the broadband light from the connector means (2) and functions as a sensor of temperature and/or strain in an object. Light is reflected back from the grating (4) to the connector means (2) and then passed to the grating (5) which acts as a reference grating through which a light output signal is transmitted to a detector (8) which is conveniently a photodetector. Means are provided for chirping the two gratings (4, 5) at the same bandwidth and the detector (8) measures the intensity of the received light output signal, with the intensity being monotonically related to the change in temperature and/or strain sensed by the grating (4) in the object.

Apparatus for sensing temperature and/or strain in an object with

Optical data storage

Optical devices utilizing photochromic compounds

Spatial light modulator

Organic optical waveguides and method of fabricating waveguide structures

An optical resonant assembly which has at least two stable light transmittance values dependent on incident light beams. The assembly consists of a pair of parallel partially transmission mirrors with a photochromic layer placed therebetween which has a refractive index dependent upon the intensity of incident light beams. The parallel mirrors constitute a Fabry-Perot type resonator. The incident light beams have the effect of 'couloring' or 'bleaching' the photochromatic material.

Optical resonant assembly

An optical device comprising a length of optical fibre of predetermined convex configuration supported by fibre mounting and/or attachment means, the convex outer part of the optical fibre having a portion thereof removed therefrom closely adjacent to or even just entering the core of the optical fibre to produce a substantially flat surface therealong on which a reflective diffraction grating of predetermined form is provided according to the function requirements of the device.

Optical fibre reflective diffraction grating devices

A method of fabricating optical sensing devices for detecting displacement of a part thereof comprising the steps of bonding a multiplicity of optical devices to one surface of a relatively large transparent substrate so that the optical devices are accurately located relative to one another and to the substrate itself, securing to the opposite surface of the substrate and one surface of a transparent optical element-carrying substrate in parallel relationship thereto resilient spacer support means and dividing the entire assembly into individual unit parts each of which comprises an optical device bonded to one substrate unit and coupled to another substrate unit having its own optical element by a divided part of the resilient spacer support means so that the two substrate units are resiliently mounted relative to one another whereby relative movement between the two substrate units produces variations in the optical characteristics of the device which can be sensed.

Method for manufacture of optical devices

Growing community of inventors

Birmingham, United Kingdom

Ian Bennion