Anomalous modal structure in a waveguide with a photonic crystal core

Area of Science:

• Photonics
• Materials Science
• Waveguide Optics

Background:

• Conventional slab waveguides exhibit predictable modal behavior.
• Dielectric waveguides with photonic crystal cores offer novel optical properties.
• Understanding modal characteristics is crucial for device design.

Purpose of the Study:

• To analyze the modal behavior of dielectric waveguides featuring a photonic crystal core.
• To compare the modal characteristics with conventional slab waveguides.
• To explore the potential for realizing single-mode waveguides with strong confinement.

Main Methods:

• Constant frequency contour analysis was employed.
• Three-dimensional finite-difference time-domain (FDTD) simulations were utilized for confirmation.

Main Results:

• The modal behavior differs significantly from conventional slab waveguides.
• The lowest-order guided mode can exhibit odd symmetry or multiple nodal planes.
• Multiple single-mode operation regions with distinct modal profiles were identified.
• A single-mode waveguide with a large core and strong confinement was demonstrated.

Conclusions:

• Photonic crystal core waveguides display unique and tunable modal properties.
• These structures offer design flexibility not found in conventional waveguides.
• The findings pave the way for advanced optical device development.