The grating has a significant role in sensing applications. Similarly, the grating-assisted coupler has excellent potential in chemical sensing applications. The power coupling between two closely coupled waveguide couplers can be significantly tuned by incorporating grating between them. The grating has been taken of silica material with sinusoidal shape in variation. The grating layer is assumed to be embedded within the sensing layer while considering a changeable effective refractive index depending on the sensing layer substances. In the present paper, grating assisted directional coupler has been numerically analysed using its own developed MATLAB-based algorithm of finite difference method (FDM) scheme. FDM method has been applied to solve the Eigenvalue equation to obtain allowed Eigenvalues and corresponding Eigen vectors (TE and TM cases). In FDM, the analysis domain has been fine discretized into the mesh of 1-D equal spacing for reasonable accurate computation results. In experimental validation, Fibre Bragg grating (FBG) has been suspended between two high refractive index coupler regions, which act as a power coupling zone. Also, the coupling length has been changed from 5 to 20 \(\upmu\)m for tuning purposes and then optimized for grating parameters viz. length, period, etc. The whole structure is 2-Dimensional (x and y directions) with invariant in the y-direction.

光栅在传感应用中具有重要作用。类似地，光栅辅助耦合器在化学传感应用中具有出色的潜力。两个紧密耦合的波导耦合器之间的功率耦合可以通过在它们之间加入光栅来显着调整。光栅采用具有正弦形状变化的二氧化硅材料。假设光栅层嵌入在传感层内，同时考虑到取决于传感层物质的可变有效折射率。在本文中，光栅辅助定向耦合器已使用其自己开发的基于 MATLAB 的有限差分法 (FDM) 方案算法进行了数值分析。FDM 方法已被应用于求解特征值方程以获得允许的特征值和相应的特征向量（TE 和 TM 情况）。在 FDM 中，分析域已被精细离散化为一维等间距的网格，以获得合理准确的计算结果。在实验验证中，光纤布拉格光栅 (FBG) 已悬挂在两个高折射率耦合器区域之间，充当功率耦合区。此外，耦合长度已从 5 更改为 20\(\upmu\) m 用于调谐目的，然后针对光栅参数进行优化。长度、周期等。整个结构是二维的（x 和 y 方向），在 y 方向上保持不变。