Highly sensitive cladding-etched arc-induced long-period fiber gratings for refractive index sensing

Curing Monitoring of Graphite/Epoxy Laminated Composite Material by Using Embedded Corrugated Long-Period Fiber Grating Sensor

“…The long-period fiber grating (LPFG) is one such candidate finding increasing applications as a sensor in aerospace, structural, medical and chemical applications for temperature, strain, and general structural health monitoring. (3,4) LPFG sensors have a lot of advantages such as electrically passive operation, light weight, immunity to electromagnetic interference, corrosion resistance, and high temperature resistance. Therefore, optical fiber sensors have been extensively applied to various fields.…”

Sensitization of hybrid LPFG–FBG refractometer using double-pass configuration

“…One of the problems faced by LPFG as an RI sensor is due to the relatively small shift in the resonant wavelength and the difficulty in identifying the center wavelength of the LPFG notch due to its large bandwidth. Various research works have been focused on improving the sensitivity of the wavelength shift through structure modification methods such as claddingetched [7][8][9] and surface coating [10][11][12]. On the other hand, some research works on hybrid LPFG-FBG configuration introduced by Patrick et al [13] have utilized the reflected signal from the FBG for RI [14,15], temperature [16], and RI/temperature simultaneous sensing [17].…”

Optical Fibre Long-Period Gratings Functionalised with Nano-Assembled Thin Films: Approaches to Chemical Sensing

“…Optical fibre sensors, as a result of their advantages such as high sensitivity, compactness, remote measurement and multiplexing capabilities, have attracted a great deal of attention for the development of refractometers and chemical sensors [4,5,6]. Refractometers and chemical sensors based on optical fibre gratings, both fibre Bragg gratings (FBGs) and long period gratings (LPGs), have been extensively employed for refractive index measurements and monitoring associate chemical processes since they offer wavelength-encoded information, which overcomes the referencing issues associated with intensity based approaches.…”

“…LPGs in liquid filled solid-core photonic bandgap fibre have been shown to exhibit a sensitivity of 17,900 nm/RIU to changes in the RI of the liquid [21], but the requirement to fill the fibre with the liquid of interest may limit application as a refractometer. In order to improve the sensitivity of the LPGs written in standard optical fibre configurations to surrounding RI, approaches such as tapering the fibre [22] or etching the cladding [23,24] have been investigated. Tapering the fibre to a diameter of 25 m allowed the demonstration of an LPG with a sensitivity of 715 nm/RIU [22].…”