Light diffraction in slab waveguide lenses simulated with the stepwise angular spectrum method.

Area of Science:

• Integrated optics
• Computational electromagnetics
• Wave propagation modeling

Background:

• Planar lens-like structures in integrated optics are crucial for beam manipulation.
• Simulating wave propagation in complex geometries, especially with curved interfaces, presents significant computational challenges.
• Existing methods may struggle with accuracy or efficiency for large-scale photonic devices.

Purpose of the Study:

• To introduce a novel stepwise angular spectrum method (SASM) for accurate wave propagation analysis in integrated optical structures with curved interfaces.
• To validate the SASM's effectiveness for both 2D and 3D slab waveguide lenses.
• To demonstrate the method's capability for simulation-based design and optimization of complex optical setups.

Main Methods:

• Derivation and application of the stepwise angular spectrum method (SASM) for curved interfaces.
• Modeling of lens-like structures using photonic slab waveguides of varying thicknesses connected by curved surfaces.
• Integration of SASM with full vectorial finite element computations for simulating 3D wave propagation, including reflection and scattering losses.

Main Results:

• The SASM accurately models wave propagation in planar lens-like integrated optical structures.
• Excellent agreement was observed between SASM results and rigorous numerical simulations of full structures.
• The proposed method achieves substantial reductions in computational effort compared to traditional simulations.

Conclusions:

• The stepwise angular spectrum method (SASM) provides an efficient and accurate tool for simulating wave propagation in complex integrated optical devices with curved interfaces.
• SASM is suitable for the design and optimization of large-scale photonic slab waveguide lenses.
• This method facilitates the development of advanced integrated optical systems by reducing simulation complexity.