Enhanced resolution of long-period grating bend sensor

Long-period gratings in special geometry fibers for high-resolution and selective sensors

“…This must be taken into consideration for a given application, where it needs to be controlled and/or exploited. With appropriate recoating, the D-shaped fiber can be protected against the surroundings; this has been recently demonstrated with a low-index coating (refractive index 1.375), 9 although the sensitivity is reduced as the index step to the recoating is smaller than to air. Additionally, the D-shaped fiber LPG sensor can have patterns created on the flat side: e.g., for quasiphase-matched nonlinear processes 11 or grating-assisted couplers.…”

“…This device was embedded and utilized as a bend sensor for wind turbines. 9 Additionally, a second LPG device was written, where the center wavelengths of the two LPGs were misaligned- Fig. 8 shows the transmission spectrum of this device, with a dip near 1510 and 1530 nm for the two LPGs, respectively.…”

“…5 This principle has been demonstrated for various sensing applications such as refractive index and bends sensing. [7][8][9] Utilizing this principle in special fibers with and without access along the fiber to the surroundings provides devices for a large number of applications. It has been demonstrated that LPGs are suitable for structural health monitoring, especially for large structures such as wind turbines, as they can provide directional bend sensing of the blades, due to the fiber geometry.…”

Drug-Induced T-Wave Morphology Changesn

“…Only a negligible change in FWHM and centre wavelength was observed, the model in the previous chapter predicted an up to 15 nm change, however it is also stated that only a very small change in intensity distribution in the surroundings shifts the wavelength similar. [104] When an object is bending, there will be a compression on one side of the material (concave side) and an expansion on the other side (convex side). For small bends the elasticity (Young's modulus) can be assumed identical on both sides, and therefore equal on both sides, and there will be none compression or expansion in the middle of the object.…”

“…These LPGs have approximately a ~10 dB transmission dip centre near 1560 nm. Two successful MZ sensors were written shown in figure 25, 26, 27 and 28 * , * Note, in [104] sensor 2 was shown before embedding, this must have been sensor 1.…”