High-efficiency and broadband photonic polarization rotator based on multilevel shape optimization

Area of Science:

• Photonics and Optical Engineering
• Computational Electromagnetics
• Nanophotonics

Background:

• Photonic polarization rotators are crucial components in optical systems.
• Existing designs often face limitations in efficiency and footprint.
• Shape optimization techniques are employed to enhance photonic device performance.

Purpose of the Study:

• To develop a novel photonic polarization rotator design.
• To improve the efficiency and performance of polarization rotators through multilevel shape optimization.
• To demonstrate the advantages of the proposed design over state-of-the-art methods.

Main Methods:

• Utilizing a topological optimization scheme for iterative shape modification.
• Implementing a two-level discrete optimization approach along the etching direction.
• Performing numerical simulations to evaluate device performance.

Main Results:

• Achieved a polarization conversion efficiency of 98.5%.
• Demonstrated insertion losses below 0.35 dB over a 100 nm bandwidth.
• Showcased significant performance improvements compared to single-level shape optimization for a given device length.
• The optimized device has a compact footprint of 6 μm × 1 μm.

Conclusions:

• Multilevel shape optimization offers a superior approach for designing high-performance photonic polarization rotators.
• The novel design achieves state-of-the-art efficiency and low insertion loss in a compact footprint.
• This work paves the way for more efficient and compact integrated photonic devices.