Reconfigurable mode converter based on a Sb₂Se₃ phase change material and inverse design

Area of Science:

• Photonics
• Integrated Optics
• Materials Science

Background:

• Mode division multiplexing (MDM) systems require efficient on-chip mode converters.
• Silicon photonics offers a robust platform for integrated optical devices.
• Phase-change materials like Sb2Se3 enable tunable optical properties.

Purpose of the Study:

• To design and demonstrate an on-chip mode converter using a silicon-Sb2Se3 hybrid platform.
• To achieve flexible switching between basic and higher-order optical modes.
• To enable advanced functionalities like switchable mode conversion and controllable beam splitting.

Main Methods:

• Inverse design principles were employed for device optimization.
• A silicon-Sb2Se3 hybrid platform was utilized for device fabrication.
• Controllable phase change regions in Sb2Se3 were used to drive mode switching and power control.

Main Results:

• A 1x2 mode converter demonstrated TE0 to TE0/TE1 conversion with low insertion loss (<0.8 dB) and crosstalk (< -13 dB) in the C-band.
• A 1x3 switchable three-mode converter was developed, enabling flexible TE0, TE1, or TE2 output.
• A 1x2 controllable beam splitter achieved 36 levels of power splitting (>5-bit) by modulating Sb2Se3 crystallinity.

Conclusions:

• The developed silicon-Sb2Se3 hybrid devices offer efficient on-chip mode conversion and signal routing capabilities.
• These devices have significant potential for broadband optical signal processing in MDM systems and optical interconnections.
• The demonstrated technology paves the way for high-density integration in future photonic chips.