Ultra-broadband transmissive gradient metasurface based on the topologically coding optimization method.

Area of Science:

• Electromagnetics
• Materials Science
• Nanotechnology

Background:

• Metasurfaces offer novel methods for controlling electromagnetic (EM) wave wavefronts.
• Phase modulation is crucial for EM wave control, typically achieved by altering meta-atom size.
• Designing broadband transmissive metasurfaces with linearly varying phase against frequency is challenging.

Purpose of the Study:

• To propose a 0-1 coding method utilizing a genetic algorithm (GA) for broadband linear transmission phase and high transmission amplitude.
• To design and verify a beam-bending metasurface using this novel method.

Main Methods:

• A 0-1 coding strategy was employed in conjunction with a genetic algorithm (GA).
• A metasurface beam deflector was designed using an array of six meta-atoms with a 60° step gap.
• Simulations and experimental validations were conducted to assess performance.

Main Results:

• The metasurface deflector demonstrated perfect beam refraction across the 8 to 12 GHz frequency range.
• Theoretical calculations were consistent with simulation and experimental outcomes.
• A stable working efficiency of approximately 75% was maintained across frequencies.

Conclusions:

• The proposed 0-1 coding method effectively achieves broadband linear transmission phase and high amplitude.
• The developed metasurface exhibits stable performance and is suitable for beam bending applications.
• This approach provides a new perspective for designing broadband metasurface devices.