A simple method for metal re-coating of optical fibre Bragg gratings

An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron–Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications

“…A common solution is to encapsulate an optical fiber sensor with an epoxy, which is indeed a simple method at room temperature, but most epoxies degrade after exposure to high temperatures over 400 °C. To overcome the limitation of this conventional encapsulation method, an all-metal packaging process has been proposed for protecting the bare RFBGs from environmental attack as well as easily attaching the RFBG-based strain sensors to metallic high-temperature components [16,17]. The process generally includes two steps.…”

“…The process generally includes two steps. In the first step, one- or two-layer metallic films are typically deposited on the bare RFBGs as an adhesive and/or conductive layer by low temperature processes such as electroless plating [16,18], physical vapor deposition (e.g., magnetron sputtering [17,19] and evaporation deposition [20]), and laser-assisted maskless micro-deposition [21]. This occurs in order to achieve reliable bonding between glass and metal, in addition to allowing to electroplate nickel coating on the metallic films as a protective layer.…”

Theoretical design and analysis of a sensing system for high pressure and temperature measurement in subsea underwater applications

“…Several techniques of metallic coating on FBG have been studied [13][14][15][16]. Some metallic coatings applied to optical fibre using techniques such as electroless plating, physical vapour deposition (PVD), and thermal spraying are silver, aluminum, copper, nickel, gold, titanium and lead.…”

In-situ strain sensing with fiber optic sensors embedded into stainless steel 316

“…These metal jackets are typically applied by low temperature processes such as electroless plating [9] or a mixture of electro-plating and magnetron sputtering [10]. Subsequently, the jacketed fibers are encapsulated either by using low temperature manufacturing processes such as ultrasonic consolidation [11] or by using brazing [12] and high temperature additive manufacturing processes such as fused deposition modelling [10]. Low temperature embedding processes inherently limit the range of applications that the final component may be used in and the high temperature approach described by Li [10] requires very thick nickel fiber jackets which significantly change the final component mechanical and material properties.…”