Broadband Spin-Dependent Directional Coupler via Single Optimized Metallic Catenary Antenna

Area of Science:

• Integrated Optics
• Nanophotonics
• Waveguide Devices

Background:

• Traditional waveguide couplers suffer from narrow operating bands and fixed unidirectional light transmission.
• Existing devices often require linear polarized light for unidirectional operation, limiting versatility.

Purpose of the Study:

• To design and demonstrate a broadband polarization directional coupler for enhanced integrated optical devices.
• To overcome the limitations of conventional couplers regarding bandwidth and polarization dependence.

Main Methods:

• Integration of a metallic catenary antenna with a silicon-on-insulator (SOI) waveguide.
• Optimization of antenna geometry using a genetic algorithm.
• Numerical simulations to evaluate performance under circularly polarized light.

Main Results:

• Achieved a wide operation band of 300 nm (1400–1700 nm).
• Maintained an extinction ratio greater than 18 dB across the operational bandwidth.
• Demonstrated tunable bidirectional light transmission by controlling incident light's rotation direction.

Conclusions:

• The developed broadband polarization directional coupler shows significant potential for advanced integrated optoelectronic and on-chip optical systems.
• The device offers superior performance compared to traditional couplers, particularly in terms of bandwidth and polarization control.