Fiber-Optic Cavity Ring Down Using an Added-Signal for Curvature Sensing

• Autor(a) principal: Susana Oliveira Silva
• Data de Publicação: 2015
• Outros Autores: Biswas,P, Bandyopadhyay,S, Pedro Jorge, Manuel Joaquim Marques, Orlando Frazão
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://repositorio.inesctec.pt/handle/123456789/6550; http://dx.doi.org/10.1109/lpt.2015.2453124

This letter presents a fiber-optic cavity ring down (CRD) configuration using an added-signal for curvature sensing. An optical time-domain reflectometer was used to send impulses down into the fiber loop cavity, inside of which a long period grating was placed to act as a sensing device. The added-signal was obtained by the sum of several conventional CRD impulses, thus providing an improvement on the curvature sensitivity when compared with the conventional CRD signal processing. A linear response to applied curvature in the range of 2.2-3.6 m(-1) was observed, and a sensitivity of 15.3 mu s/m(-1) was obtained. This result was found to be 20-fold the one obtained for the conventional CRD signal processing. The added-signal increases the optical power but increases as well the ring-down time due to the sum of the several loops that light travels inside the ring. A ring-down time response of 43.3 mu s was attained (versus 23.7 mu s for the conventional CRD signal processing).