Sensitivity analysis of fiber bragg grating sensors coated by metal films produced by the laser-assisted maskless microdeposition process

Abstract

The sensitivity required for optical fiber sensors such as fiber Bragg gratings (FBG) is highly dependent on applications, environment of use and the magnitude of physical parameters measured by the sensor. In addition, such sensitivity dependency is more complicated if FBGs are embedded in metallic structures using laser-assisted additive manufacturing. One of the methodologies for the improvement of the sensitivity of FBGs is to coat them with thin films. The coating not only protects the optical fiber sensors but also improves their sensitivity. In this paper, we propose a combined coating process for on-fiber thin film deposition using Laser Assisted Maskless Microdeposition (LAMM) followed by electroless Ni plating. An analytical/numerical model is also developed to study the effect of coating thickness on the sensor sensitivity. In addition, the role of laser parameters on the coating characteristics such as appearance quality and compositions is experimentally investigated.The sensitivity required for optical fiber sensors such as fiber Bragg gratings (FBG) is highly dependent on applications, environment of use and the magnitude of physical parameters measured by the sensor. In addition, such sensitivity dependency is more complicated if FBGs are embedded in metallic structures using laser-assisted additive manufacturing. One of the methodologies for the improvement of the sensitivity of FBGs is to coat them with thin films. The coating not only protects the optical fiber sensors but also improves their sensitivity. In this paper, we propose a combined coating process for on-fiber thin film deposition using Laser Assisted Maskless Microdeposition (LAMM) followed by electroless Ni plating. An analytical/numerical model is also developed to study the effect of coating thickness on the sensor sensitivity. In addition, the role of laser parameters on the coating characteristics such as appearance quality and compositions is experimentally investigated.