Fiber-to-chip grating coupler on 4H-silicon-carbide-on-insulator platform with high-efficiency

Area of Science:

• Photonics and optical engineering
• Materials science
• Semiconductor device physics

Background:

• Integrated photonics requires efficient fiber-to-chip interfaces.
• 4H-silicon-carbide-on-insulator (4H-SiCOI) is an emerging platform with unique material properties.
• Transverse electric (TE) polarization is crucial for many photonic applications.

Purpose of the Study:

• To demonstrate a high-performance fiber-to-chip grating coupler on the 4H-SiCOI platform.
• To achieve high coupling efficiency and low back-reflection for TE polarization.
• To validate the fabrication simplicity and effectiveness of the proposed design.

Main Methods:

• Design combining apodized diffractive gratings with subwavelength gratings.
• Optimization using an intelligent algorithm.
• Fabrication via a single-mask process using lithography and etching.

Main Results:

• Peak coupling efficiency of -1.79 dB (66.2%) at 1549.7 nm.
• 1-dB bandwidth of 31 nm.
• Back reflectance below -17 dB (2%) across the 1541-1564 nm wavelength range.

Conclusions:

• The demonstrated grating coupler offers excellent performance for TE polarization on the 4H-SiCOI platform.
• The design and fabrication approach are suitable for integrated photonic applications.
• This work advances the capabilities of 4H-SiCOI for optical communication and sensing.