Highly compact circulators in square-lattice photonic crystal waveguides

Area of Science:

• Photonics
• Optoelectronics
• Waveguide devices

Background:

• Photonic crystal waveguides offer unique light manipulation properties.
• Compact and efficient circulators are crucial components in optical systems.
• Existing circulator designs often face challenges with size and performance.

Purpose of the Study:

• To propose and demonstrate a highly compact circulator.
• To achieve ultra-low insertion loss and high isolation.
• To investigate the operating mechanism in square-lattice photonic crystal waveguides.

Main Methods:

• Utilizing a single magneto-optical square rod at the waveguide intersection.
• Replacing surrounding square rods with right-angled-triangle rods.
• Applying the finite-element method and Nelder-Mead optimization.

Main Results:

• Achieved an insertion loss of 0.02 dB for transmitted waves.
• Obtained ultra-high isolation ranging from 46 dB to 48 dB.
• Demonstrated a compact and efficient circulator structure.

Conclusions:

• The proposed design enables highly compact and efficient circulators.
• The method is applicable to various wavebands, including microwave and Terahertz.
• This work advances the development of integrated photonic devices.