1：Experimental Design and Method Selection:

The study used a simulation-based approach with OptiFDTD software to model the mode converter. The design involved two identical multi-ring core fibers (M-RCFs) with lateral misalignment (distance x and height y) to achieve mode conversion from LP11 to LP01. Theoretical models for coupling coefficients and mode orientations were employed.

2：Theoretical models for coupling coefficients and mode orientations were employed. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: The fibers were simulated with specific parameters (e.g., refractive indices, core radii) as detailed in Table 1. No physical samples were used; all data were generated through simulations.

3：No physical samples were used; all data were generated through simulations. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: The primary tool was OptiFDTD software for simulation. Materials included dielectric fibers with defined refractive index profiles, and air as the surrounding medium. No physical equipment was mentioned.

4：Experimental Procedures and Operational Workflow:

Fiber A was cleaved at a 42° angle based on preliminary studies of coupling effects. Fiber B was held horizontal. The lateral displacement y and separation distance x were adjusted to maximize coupling power. Simulations were run for 4000 time steps with a cell size of 100 nm, using a continuous wave source at 1.55 μm wavelength.

5：55 μm wavelength. Data Analysis Methods:

5. Data Analysis Methods: Power measurements were taken at various points (input, cleaved point, input of fiber B, output) using observation lines in the software. Coupling efficiency and losses were calculated based on power differences.