Abstract: A regenerated optical waveguide is fabricated by hydrogenating an optical waveguide (12) and exposing a grating section (28) to a UV laser beam interference fringe pattern (14) to form a Type I grating. The grating section (28) 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.

Abstract: 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.

Abstract: A waveguide 10 is located beside a phase mask 12, which is driven, with a ramp waveform, to undergo oscillating motion along its longitudinal axis. The phase mask 12 is illuminated with a CW UV laser beam 16, thereby generating a UV interference fringe pattern extending across the waveguide 10. The waveguide 10 moves continuously in one direction along its longitudinal axis, past the phase mask 12. Each period of the ramp waveform comprises two parts: the first part causes the phase mask 12 to move, in the same direction and at the same speed as the waveguide 10, for a distance equal to the width of the fringe pattern. As a result, the UV interference fringe pattern moves along with the waveguide 10, and a section of grating is fabricated. The second part causes the phase mask 12 to move rapidly in the opposite direction, flying back to its starting position and the next section of the grating is fabricated.

Abstract: An optical interrogation system 10 includes optical amplifying and gating apparatus, in the form of a semiconductor optical amplifier (SOA) 14 and an optical source 12, 14. Drive apparatus 22 (an electrical pulse generator driven by a variable frequency oscillator) is provided to generate electrical drive pulses (see inset (a)) which are applied to the SOA 14, to cause the SOA 14 to switch on and off. The optical source comprises a super-luminescent diode (SLD) 12, the CW output from which is gated into optical pulses by the SOA 14. The SOA 14 is optically coupled to the waveguide 16 containing an array of reflective optical elements (gratings G) to be interrogated. The interrogation system further includes an optical detector 18, optically coupled to the SOA 14, operable to evaluate the wavelength of a returned optical pulse transmitted by the SOA 14.

Abstract: A first embodiment of the invention provides a Gires-Tournois etalon (DGTE) 20 comprising a cladding mode suppressed optical fibre 22, including an etalon section 24 in which a weakly reflective optical waveguide grating 26 and a strongly reflective optical waveguide grating 28 are provided. The two gratings 26, 28 are chirped fibre Bragg gratings (FBGs). The chirped FBGs 26, 28 are arranged to together define an etalon cavity. Another aspect of the invention provides a dispersion compensator 60 comprising two DGTEs 62, 64 according to the first embodiment of the invention The DGTEs 62, 64 have a linearly varying dispersion over a selected optical bandwidth. The first DGTE 62 has a positive dispersion slope and the second DGTE 64 has a negative dispersion slope. The magnitudes of the dispersion slopes of the two DGTEs 62, 64 are substantially equal, so that the dispersion compensator 60 has a constant dispersion across the selected bandwidth.

Abstract: 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 wavelguide. 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.

Abstract: A regenerated optical waveguide is fabricated by hydrogenating an optical waveguide (12) and exposing a grating section (28) to a UV laser beam interference fringe pattern (14) to form a Type I grating. The grating section (28) 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.

Abstract: An optical pulse transmission line portion 10, having dispersion slope compensation, comprising an optical waveguide 12 (length L1, dispersion parameter D1) having a dispersion slope parameter (S1) of a first sign, and dispersion compensation means 14 (length L2, dispersion parameter D2) having a dispersion slope parameter (S2) of the opposite sign.