Compact and high-power Ge-on-Si photodetector based on butt-side-hybrid coupling

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Germanium-on-silicon (Ge-on-Si) photodetectors (PDs) are crucial for silicon photonics.
• A key limitation of current Ge-on-Si PDs is their relatively low saturation power.

Purpose of the Study:

• To propose and simulate a compact, high-power lateral PIN Ge-on-Si PD.
• To mitigate the saturation effect in Ge-on-Si PDs through a novel coupling structure.

Main Methods:

• A novel butt-side-hybrid coupling structure was designed and simulated.
• Input light is split into three paths for controlled coupling.
• Field distribution and mode conversion were engineered for uniform optical power distribution.

Main Results:

• The proposed Ge-on-Si PD achieved a saturation power of 23 mW under -3 V bias.
• A maximum current density of 5.60 mA/μm³ was recorded.
• The device has a compact footprint of 7 μm × 30 μm.

Conclusions:

• The novel butt-side-hybrid coupling structure effectively mitigates saturation in Ge-on-Si PDs.
• The compact and high-power PD is suitable for high-density silicon photonic integration.