Long period fiber grating and high sensitivity refractive index sensor based on hollow eccentric optical fiber

High sensitivity refractive index sensor based on a tapered small core single-mode fiber structure

“…The maximum sensitivities for S-18.8, S-15.0, and S-12.5 are 4722.9 nm∕RIU (RI 1.4249-1.4319), 8353.6 nm∕RIU (RI 1.4256-1.4312), and 19212.5 nm∕RIU (RI 1.4304-1.4320), respectively. Taking into account that the OSA has a wavelength resolution of 0.01 nm, the RI sensor based on S-12.5 has an RI resolution of 5.025 × 10 −7 which, to the best of our knowledge, is significantly higher than previously reported [16][17][18][19][20]. It is noted that, in this Letter, the central wavelength of the spectral dip is determined as the 3 dB mean wavelength, which is a more reliable parameter compared to the central peak wavelength.…”

Sensing Characteristics of Tilted Long Period Fiber Gratings Inscribed by Infrared Femtosecond Laser

“…This is caused by the formation of resonance loss peaks through coupling between the core mode and several high-order cladding modes, which are highly sensitive to outer cladding mediums. As such, TLPFGs have been used as refractive index sensors in a variety of studies [ 26 , 27 , 28 ].…”

Temperature-calibrated high-precision refractometer using a tilted fiber Bragg grating

“…As a result, the Abbe refractometer can measure the absolute RI without a reference. Fiber optic-based approaches offer advantageous remote, in-situ, and distributed measurement of surrounding RI, and a lot of research efforts employing fiber gratings and interferometers [4][5][6][7][8][9][10][11] are being developed for compact, cost-effective, and high-accuracy RI measurement. Among them based on fiber gratings, tilted fiber Bragg gratings (TFBGs) have demonstrated outstanding performance in high-sensitivity RI measurement by taking advantages of well-established FBG technology and resonant excitations of cladding modes [12].…”