Broadband waveguide intersections with low cross talk in photonic crystal circuits

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Photonic crystal (PC) circuits offer miniaturization and enhanced optical functionalities.
• Efficient waveguide intersections are crucial for complex PC-based optical circuits.
• Existing methods often struggle with broad bandwidth and low cross talk.

Purpose of the Study:

• To propose a novel mechanism for constructing waveguide intersections in PC circuits.
• To achieve broad bandwidth and low cross talk in these intersections.
• To demonstrate the feasibility of this mechanism through numerical simulations.

Main Methods:

• Utilizing coupled-cavity waveguides (CCWs) combined with conventional line-defect waveguides.
• Leveraging the dependence of defect coupling on field patterns and defect alignment (coupling angle) in CCWs.
• Designing defect modes and employing the finite-difference time-domain (FDTD) method for simulation.

Main Results:

• Successfully demonstrated a waveguide intersection in a 2D triangular lattice PC.
• Simulations showed negligible pulse distortion for a 500-fs pulse at ~1.3 micrometers.
• Achieved low cross talk, indicating efficient signal routing.

Conclusions:

• The proposed mechanism provides a viable solution for high-performance waveguide intersections in PC circuits.
• This method is applicable to standard dielectric PCs with triangular lattices.
• The findings pave the way for more complex and efficient integrated photonic devices.