Multilayer stacked crystalline silicon switch with nanosecond-order switching time

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Three-dimensional (3D) integration is crucial for developing compact and dense photonic integrated circuits (PICs).
• Wafer bonding offers a promising technique for fabricating complex 3D PICs.

Purpose of the Study:

• To demonstrate a 3D integrated silicon photonic platform fabricated via wafer bonding.
• To evaluate the performance of optical components and switching speed in a 3D integrated platform.

Main Methods:

• Fabrication of a 3D integrated silicon photonic platform using wafer bonding.
• Integration of optical components like multimode interferences (MMIs), waveguide crossings, and Mach-Zehnder interferometer (MZI)-based switches in different layers.
• Characterization of interlayer coupling loss, crosstalk, and switch response time.

Main Results:

• All layers of the platform are fabricated using c-Si, ensuring high carrier mobility for nanosecond response times.
• Interlayer couplers and crossings achieved a low 0.98 dB coupling loss and <-43.58 dB crosstalk.
• Intra-layer crossings exhibited <-36.00 dB crosstalk, and nanosecond-order switching was confirmed.

Conclusions:

• The demonstrated wafer-bonded 3D silicon photonic platform enables high-performance optical components and fast switching.
• This approach is suitable for realizing compact and dense PICs with advanced functionalities.