High performance ultra-compact SOI waveguide crossing.

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Nanophotonics

Background:

• Waveguide crossings are essential for advanced photonic integrated circuits (PICs), enabling functionalities like optical switching and routing.
• Existing high-performance waveguide crossings on silicon-on-insulator (SOI) platforms often require significant footprints, limiting device density.
• Reducing the physical size of waveguide crossings is crucial for the development of large-scale and high-density PICs.

Purpose of the Study:

• To experimentally demonstrate an ultra-compact waveguide crossing with a minimized footprint on a silicon photonic platform.
• To achieve low insertion loss and low crosstalk in a significantly reduced device size.
• To validate the performance of the compact waveguide crossing across the C-band wavelength range.

Main Methods:

• Utilizing a silicon photonic platform for fabricating the waveguide crossing.
• Designing and simulating the waveguide crossing structure to predict performance metrics.
• Experimental fabrication and characterization of the ultra-compact waveguide crossing.

Main Results:

• An ultra-compact waveguide crossing with a footprint of approximately 1 × 1 μm² was successfully fabricated.
• Simulations predicted low insertion loss (< 0.175 dB) and crosstalk (< -37 dB) across the C-band.
• Experimental results showed an insertion loss below 0.28 dB and crosstalk around -30 dB over the C-band.

Conclusions:

• The demonstrated ultra-compact waveguide crossing represents a significant advancement for high-density PICs.
• The device offers a compelling balance between minimal footprint and high optical performance (low loss and crosstalk).
• This technology is vital for enabling next-generation optical switches, routers, and complex photonic systems.