Polarization-insensitive and broad-angle self-collimation in a two-dimensional photonic crystal with rectangular air...

Area of Science:

• Photonics
• Condensed Matter Physics
• Materials Science

Background:

• Photonic crystals (PhCs) offer unique light manipulation properties.
• Self-collimation enables waveguiding without defects.
• Achieving polarization-insensitive and broad-angle self-collimation is crucial for integrated photonic devices.

Purpose of the Study:

• To investigate polarization-insensitive and broad-angle self-collimation in 2D square-lattice PhCs with rectangular air holes.
• To analyze the impact of rectangular air hole geometry on photonic band structures and equi-frequency contours (EFCs).
• To explore the potential for enhanced performance and fabrication convenience.

Main Methods:

• Systematic investigation of band structures and EFCs for PhCs with varying rectangular air hole dimensions (L and W).
• Analysis of dispersion properties to identify conditions for polarization-insensitive self-collimation (PISC).
• Evaluation of EFC flatness for broad-angle self-collimation capabilities.

Main Results:

• Rectangular air holes facilitate PISC more readily than circular or square holes, with tunable performance.
• Long, flat EFCs for the TM-3 band enable broad-angle self-collimation.
• A specific configuration (L=0.5a, W/L=0.8) results in a 1D grating PhC with ~19.98% relative bandwidth for all-angle self-collimation.

Conclusions:

• 2D PhCs with rectangular air holes provide a flexible platform for achieving both polarization-insensitive and broad-angle self-collimation.
• The proposed design offers superior performance and a more convenient fabrication process compared to previous methods.
• This research paves the way for advanced photonic integrated circuits and devices.