Improved detecting sensitivity of long period fiber gratings by polyelectrolyte multilayers: The effect of film structures

An Ultrasensitive Long-Period Fiber Grating-Based Refractive Index Sensor with Long Wavelengths

“…Even when the RI of the environmental media is close to that of the cladding, the RI sensitivity is generally only a few hundred nanometers per unit of RI. For example, in the previous literature [15], the most sensitive RI region for the etched LPFG was 1.400–1.453. The maximum sensitivity is about ~789.47 nm/RIU.…”

“…What is more, the sensitivity and sensitive range of this LPFG sensor to RI can continue to be improved and adjusted by coating nanofilm on the surface of the LPFG [10,15,23,24,25,26]. The kinds of LPFGs with a period of 180 µm and red-shifted resonant peaks are extremely conducive to applications in physical, biological, and chemical sensing due to their overwhelmingly high RI sensitivity.…”

Label-free fiber optic biosensor based on thin-core modal interferometer

“…This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ PSAMs permit a diverse array of materials, such as the displaced molecules, ions, and proteins, to be passed through them, providing an ideal platform for interaction between the fiber probe and its surrounding materials, particularly in direct protein immobilization. It has also been implemented with success in numerous other chemical applications, including in the measurement of pH [14], relative humidity (RH) [15], and refractive index (RI) [16]. Biotin-streptavidin system has been widely used for biological applications, and many detection approaches with FOBs exists [4,5,17].…”

Five–Layer Long Period Grating Architecture: A Tool for More Accurate Interpretation of Bio-molecular Interaction

“…In recent years long period grating (LPG) with a high refractive index overlay has been widely studied for label free bio-sensing applications [1][2][3]. The basic idea of enhancing the refractive index (RI) sensitivity by deposition of a thin layer of high refractive index material between the clad and the infinite surrounding medium has been elaborated elsewhere [4,5].…”

“…Therefore, the overlay layer for a particular cladding mode to operate in the linear zone around the mode transition for a specific RI in the surrounding can easily be ascertained. In practice, overlay layer of polymers are generally deposited either using dip coating [1] or using electrostatic self assembled(ESA) layers [3] or layers of high refractive index oxide coatings using vacuum deposition technique [2]. Refractive index sensitivity s res n ∆ ∆ / λ of LPG with optimum overlay were found to be ~5500 nm/RIU [1] in the RI range of biological interest i.e.…”