1：Experimental Design and Method Selection:

The study employs finite-element-method-based software COMSOL 5.1 for numerical analysis, focusing on the excitation of long-range surface plasmon polaritons (LRSPPs) in an H-shaped microstructured optical fiber (MOF) with symmetrical dielectric–metal–dielectric waveguide (DMDW).

2：1 for numerical analysis, focusing on the excitation of long-range surface plasmon polaritons (LRSPPs) in an H-shaped microstructured optical fiber (MOF) with symmetrical dielectric–metal–dielectric waveguide (DMDW). Sample Selection and Data Sources:

2. Sample Selection and Data Sources: The sensor's performance is evaluated over a refractive index (RI) analyte range from 1.33 to 1.

3：33 to List of Experimental Equipment and Materials:

39. 3. List of Experimental Equipment and Materials: The setup includes an H-shaped silica MOF, a solid cladding of silica, a solid core of doped silica, and two side holes filled with a liquid analyte. A symmetrical DMDW, consisting of a thin gold layer and two dielectric layers, is deposited on the inner walls of the side holes.

4：Experimental Procedures and Operational Workflow:

The sensor's response is analyzed by varying the geometrical and optical parameters of the DMDW, including the thickness of the gold layer and the refractive index of the dielectric layers.

5：Data Analysis Methods:

The sensor's performance is evaluated in terms of resolution, sensitivity, full width at half maximum (FWHM), and figure of merit (FOM).