Designing a Mode Converter
アプリケーションノート
This application example demonstrates the design and simulation of a mode converter using the RSoft BeamPROP tool. Mode converters are often used to transition from a large multimode waveguide, such as an optical fiber, to a smaller single-mode planar waveguide. In this case, the converter consists of two linearly tapered rib waveguides that form a transition from a wide multimode input to a narrow single-mode silicon-on-insulator (SOI) waveguide.
The structure is created using three multilayer segments to define the SOI platform and the two tapered sections. Design variables such as the taper lengths and final taper width can be adjusted to optimize coupling efficiency. The fundamental modes of both the input and output waveguides are computed using the built-in Beam Propagation Method (BPM) mode solver. BeamPROP monitors are placed along the structure to track the power evolution and measure conversion performance.
Simulation results show approximately 93% power conversion from the input to the output mode, confirming efficient operation of the design. All output data is saved in a simple text format for easy analysis and further optimization.