Efficient silicon wire waveguide crossing with negligible loss and crosstalk

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Electrical Engineering

Background:

• Optical waveguides are crucial components in integrated photonic circuits.
• Efficient waveguide crossings are essential for complex optical routing and signal processing.
• Existing waveguide crossing designs often suffer from significant insertion loss and crosstalk.

Purpose of the Study:

• To introduce a novel, highly efficient silicon wire waveguide crossing design.
• To demonstrate the feasibility of vertical coupling between silicon wire and polymer waveguides.
• To provide a CMOS-compatible solution for advanced photonic applications.

Main Methods:

• Utilizing vertical coupling of tapered silicon wire waveguides with upper polymer wide strip waveguides.
• Employing a silica buffer layer to facilitate efficient optical power transfer.
• Performing numerical simulations using the 3D Finite-Difference Time-Domain (FDTD) method to optimize the structure.

Main Results:

• Achieved 98% efficiency for the through-pass signal.
• Achieved 99.9% efficiency for the cross-pass signal.
• Demonstrated negligible back reflection (-50 dB) and crosstalk (-70 dB) in the optimized 70 µm structure.

Conclusions:

• The proposed silicon wire waveguide crossing offers superior performance metrics.
• This design is compatible with existing Complementary Metal-Oxide-Semiconductor (CMOS) fabrication processes.
• The efficient waveguide crossing has significant potential for various applications in silicon photonics and integrated optics.