Agile Free-Form Signal Filtering and Routing with a Chaotic-Cavity-Backed Non-Local Programmable Metasurface

Area of Science:

• Electromagnetics
• Applied Physics
• Signal Processing

Background:

• Traditional filter synthesis relies on rational engineering of coupled resonators, limiting design space and tunability.
• Existing methods struggle with creating highly tunable filters due to restrictions on resonator placement.

Purpose of the Study:

• To demonstrate agile free-form signal filtering and routing using a purely optimization-based approach.
• To overcome the limitations of spatially disjoint resonators in traditional filter design.
• To achieve ultra-wideband (UWB) tunability and programmable multi-band filtering.

Main Methods:

• Utilized a multi-parameter programmable system with spatially overlapping modes.
• Employed a purely optimization-based approach for filter synthesis.
• Fabricated an all-metallic prototype with a quasi-2D chaotic cavity for strong coupling.

Main Results:

• Achieved low-loss, UWB (7.5-13.5 GHz) tunability with signal-strength-independent linearity.
• Experimentally confirmed reflectionless and transmissionless scattering modes, including exceptional points.
• Demonstrated programmable signal routing with 20 dB discrimination over 10 MHz bandwidth.
• Showcased UWB-tunable multi-band filtering with reprogrammable band characteristics.

Conclusions:

• The optimization-based approach offers a flexible and powerful alternative for advanced filter synthesis.
• The fabricated device enables efficient control of transfer functions for complex signal manipulation.
• This method significantly expands the design space for tunable filters and signal routing applications.