Low-loss waveguide bend for compact and broadband photonic integrated circuits

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Waveguide bends are crucial components in integrated optical circuits.
• Traditional bends often suffer from high insertion loss and wavelength dependency.
• Minimizing loss and ensuring broadband operation are key challenges in photonic device design.

Purpose of the Study:

• To propose and demonstrate a low-loss, wavelength-insensitive waveguide bend.
• To reduce the footprint of waveguide bends in silica-on-silicon technology.
• To improve the performance of optical delay lines.

Main Methods:

• Simulating the bending loss of a 90-degree Bloss and arc hybrid bend.
• Comparing the hybrid bend's performance to a standard circular arc bend.
• Fabricating two-meter-long delay lines using the proposed bends and straight waveguides.

Main Results:

• The proposed hybrid bend exhibits ultra-low loss (0.0014 dB/90° at 1310 nm).
• The bend demonstrates a flat spectral response across the O-, C-, and L-bands.
• Delay lines with the hybrid bend show a significantly lower propagation loss (4.20 dB/m) compared to circular arc bends (25.18 dB/m).

Conclusions:

• The novel hybrid waveguide bend offers superior performance in terms of loss and spectral flatness.
• This design provides a significant improvement for silica-on-silicon delay lines.
• The developed bend is a promising solution for advanced integrated optical circuits.