Amendment performance of an apodized tilted fiber Bragg grating for a quasi-distributed-based sensor.

In this work, the characteristics of reflectivity spectra produced inside a reflective-tilted fiber Bragg grating (R-TFBG) are investigated, seeking a remarkable performance that could be able to upgrade the sensitivity range for temperature-strain sensors of quasi-distribution type. We introduce an optimized performance through a comparative investigation among different evaluation parameters, such as core radius, tilt angle, and the elite selection of apodization profiles, in addition to the traditional parameters, such as grating length, L, and index modulation amplitude, Δn. Regarding the tilt angle, its increase affects the full width at half-maximum (FWHM) affirmatively, while having a negative impact on the maximum reflectivity.

Second harmonic generation in thin optical fibers via cladding modes.

Since silica goes under the category of amorphous materials, it is difficult to investigate important processes such as second harmonic generation (SHG) in silica-based fibers. In this paper, we proposed a method for SHG relaying on cladding modes as pump modes. Cladding modes are introduced in optical fibers through tilted long period grating (T-LPG), where power of core mode is transferred into cladding modes.

Sensitivity improvement of reflective tilted FBGs.

Tilted fiber Bragg gratings are used as energy couplers in which the core mode and cladding modes can be coupled together. Cladding modes have extensive importance in sensing applications due to their sensitive characteristics to the surrounding refractive index. The cladding modes are investigated theoretically by studying a three-layer model of optical fibers, whereas the core mode is investigated by studying a two-layer model of optical fibers.