Interrogation of fibre Bragg grating sensors using an arrayed waveguide grating

摘要

We experimentally investigate the use of an arrayed waveguide grating (AWG) to interrogate fibre Bragg grating (FBG) sensors. A broadband light source is used to illuminate the FBG sensors. Reflected spectral informationis directed to the AWG containing integral photodetectors providing 40 electrical outputs. Three methods are described to interrogate FBG sensors. The first technique makes use of the wavelength-dependent transmissionprofile of an AWG channel passband, giving a usable range of 500 u(epsilon) and a dynamic strain resolution of 96 n(epsilon) Hi~1/2 at 13 Hz. The second approach utilizes wide gratings larger than the channel spacing of the AWG; bymonitoring the intensity present in several neighbouring AWG channels an improved range of 1890 u(epsilon) was achieved. The third method improves the dynamic range by utilizing a heterodyne aPProach based on interferometricwavelength shift detection, providing an improved dynamic strain resolution of 17 n(epsilon) Hi~l/2 at 30 Hz.