Evaluation of the use of incoherent light sources in fibre grating sensing for applications in non-invasive medical diagnostics

Optical fibre sensors have attracted much attention as noninvasive electrically immune multiparameter diagnostic tools. Optical fibre gratings – resonant structures inside fibres, enable localized and distributed high-precision measurement schemes for the use in cardiology, pulmonology, prosthetics, obstetrics, etc. Particular niche market is reserved for broadband LPG sensors, which expel light from the fibre core to the cladding and thus enable sensitive measurement of the external refractive index and curvature. With the new costcutting LPG fabrication methods on the raise the question of the source and detector cost gets into focus. While the broadband coherent sources are usually used in laboratory, the source and spectrum analyser costs are prohibitive for many field applications. In this paper, we evaluate the performance and cost-benefit of the incoherent source application. The sensor performance is assessed in terms of sensing precision and signal-to-noise signal quality for broadband and lateral edge sensing schemes. It is sufficient for basic heart and respiration rate monitoring, but fails to satisfy stricter requirements for medical diagnostics.