Optical power-based interrogation of Near-infrared fibre grating spectral combs

Near-infrared fibre grating spectral combs provide a platform to measure tiny refractive index variations in the medium around an optical fibre, which has led to the development of a wide variety of sensors. Their interrogation is usually carried out by means of a spectral analysis, but simpler and more efficient techniques become really attractive for practical applications. This work reports two configurations based on the use of a broadband optical source and a photodiode as a detector, resulting very competitive in terms of cost-effective operation. They both exhibit a sensitivity value high enough to be considered as worthwhile alternatives.