All-silicon, low-cross-talk terahertz waveguide crossing based on effective medium.

Area of Science:

• Terahertz integrated photonics
• Silicon photonics
• Waveguide technology

Background:

• All-silicon effective-medium-clad waveguides offer high efficiency and broad bandwidth for terahertz applications.
• Waveguide crossings are crucial for routing and increasing circuit density in integrated platforms.
• Standard waveguide intersections cause scattering and high crosstalk, limiting performance.

Purpose of the Study:

• To propose and demonstrate a low-loss, wide-bandwidth waveguide crossing for all-silicon terahertz integrated circuits.
• To address the challenge of crosstalk in orthogonal waveguide intersections.

Main Methods:

• Utilized Maxwell-Garnet effective-medium theory for design.
• Employed wavefront planarization techniques to minimize scattering.
• Fabricated the monolithic structure using deep reactive ion etching on a silicon wafer.

Main Results:

• Achieved a 40% fractional bandwidth crossing.
• Demonstrated low insertion loss (< 1 dB).
• Measured an average crosstalk level of -39 dB for both E11x and E11y modes over 220-330 GHz.

Conclusions:

• The proposed waveguide crossing is an effective routing component for terahertz all-silicon integrated circuits.
• The demonstrated low loss and crosstalk performance are suitable for advanced terahertz systems.
• The employed design techniques are transferable to other dielectric waveguide platforms at different frequencies.