Graphene-based fine-tunable optical delay line for optical beamforming in phased-array antennas

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Antenna Technology

Background:

• Phased-array antennas require precise beamforming for applications like radar.
• Conventional radio frequency (RF) beamformers face limitations in speed, efficiency, and beam-squint effects.
• Optical delay lines offer potential advantages for high-performance beamforming.

Purpose of the Study:

• To design and report an integrated graphene-based fine-tunable optical delay line on silicon nitride.
• To enable efficient optical beamforming in phased-array antennas.
• To overcome limitations of conventional RF beamformers.

Main Methods:

• Integration of graphene-based Mach-Zehnder interferometer switches and microring resonators.
• Utilizing a graphene capacitor for voltage-controlled optical path tuning.
• Fabrication on a silicon nitride platform.

Main Results:

• Achieved a high optical delay time (τg=920 ps) in a compact footprint (4.15 mm²).
• Demonstrated optical loss <27 dB, suitable for active phased-array antennas.
• Graphene integration resulted in faster reconfiguration times and low energy dissipation with negligible beam-squint effect.

Conclusions:

• The designed graphene-based optical delay line is highly suitable for efficient beamsteering in phased-array antennas.
• This technology offers significant advantages over conventional RF beamformers.
• The device enables fine-tunable beamsteering for 20 radiating elements up to ±20° in X-band synthetic aperture radar applications.