Aston University

Aston Photonic Technologies Limited

Xuewen Shu

Ian Bennion

Catherine Anne Sugden

Kevin C Byron

Lin Zhang

Yu Liu

Donghui Zhao

Bashir Aliyu Labbo Gwandu

Lee Ann Kennedy

Filip Floreani

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

A first embodiment of the invention provides a Gires-Tournois etalon (DGTE)comprising a cladding mode suppressed optical fibre, including an etalon sectionin which a weakly reflective optical waveguide gratingand a strongly reflective optical waveguide gratingare provided. The two gratingsare chirped fibre Bragg gratings (FBGs). The chirped FBGsare arranged to together define an etalon cavity. Another aspect of the invention provides a dispersion compensatorcomprising two DGTEsaccording to the first embodiment of the invention. The DGTEshave a linearly varying dispersion over a selected optical bandwidth. The first DGTEhas a positive dispersion slope and the second DGTEhas a negative dispersion slope. The magnitudes of the dispersion slopes of the two DGTEsare substantially equal, so that the dispersion compensatorhas a constant dispersion across the selected bandwidth. The DGTEsare optically coupled to one another via a four-port optical circulator

Gires-Tournois etalons and dispersion compensation

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

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Birmingham, United Kingdom

Xuewen Shu