Ultra-compact and broadband arbitrary-to-single-mode power divider-based architecture for flexible on-chip mode...

Area of Science:

• Photonics
• Integrated Optics
• Optical Communications

Background:

• Multimode photonic systems require sophisticated mode manipulation for advanced functionalities.
• Existing methods for mode conversion and routing can be complex and bulky.

Purpose of the Study:

• To propose and demonstrate a versatile on-chip architecture for flexible multimode manipulation.
• To leverage arbitrary-to-single-mode power dividers (ASPDs) for simplified mode conversion and routing.

Main Methods:

• Designed ultra-compact ASPDs using subwavelength gratings and intelligent optimization algorithms.
• Configured two cascaded ASPD units in a Mach-Zehnder-interferometer-like structure with standard single-mode components.
• Experimentally validated the architecture for mode conversion and switching.

Main Results:

• Achieved footprints below 9.5 µm for low-order modes (TE0-TE3) with excess losses below 0.35 dB over a 300 nm bandwidth.
• Demonstrated record-wide 500 nm bandwidth (1300-1800 nm) for TE0/TE1 ASPDs with < 0.15 dB excess loss.
• Showcased scalability to higher-order modes (TE4-TE7) with compact footprints and excellent performance.

Conclusions:

• The proposed ASPD-based architecture offers a compact, scalable, and flexible solution for multimode photonic integrated circuits.
• Direct decomposition of higher-order modes simplifies routing and reduces the need for complex multimode elements.
• This platform provides a promising route toward reconfigurable multimode photonic systems.