Cusano A, Iadicicco A, Pilla P, Contessa L, Campopiano S, Cutolo A, Giordano M
Opt Express. 2006 Jan 9;14(1):19-34. doi: 10.1364/opex.14.000019.
In this work, the numerical and experimental investigation of the cladding modes re-organization in high refractive index (HRI) coated Long Period Gratings (LPGs) is reported. Moreover, the effects of the cladding modes re-organization on the sensitivity to the surrounding medium refractive index (SRI) have been outlined. When azimuthally symmetric nano-scale HRI coatings are deposited along LPGs devices, a significant modification of the cladding modes distribution occurs, depending on the layer features (refractive index and thickness) and on the SRI. In particular, if layer parameters are properly chosen, the transition of the lowest order cladding mode into an overlay mode occurs. As a consequence, a cladding modes re-organization can be observed leading to relevant improvements in the SRI sensitivity in terms of wavelength shift and amplitude variations of the LPGs attenuation bands.
在这项工作中，报道了对高折射率（HRI）涂层长周期光栅（LPG）中包层模重组的数值和实验研究。此外，还概述了包层模重组对周围介质折射率（SRI）灵敏度的影响。当沿LPG器件沉积方位对称的纳米级HRI涂层时，根据涂层特性（折射率和厚度）以及SRI，包层模分布会发生显著变化。特别是，如果适当选择层参数，最低阶包层模会转变为覆盖模。因此，可以观察到包层模重组，从而在LPG衰减带的波长偏移和幅度变化方面显著提高SRI灵敏度。
