Synthetic phonons enable nonreciprocal coupling to arbitrary resonator networks

Area of Science:

• Physics, Applied Physics, Electrical Engineering, Photonics, Acoustics, Electromagnetics

Background:

• Inducing nonreciprocal wave propagation is a fundamental challenge in various physical systems.
• Existing methods often rely on magneto-optic effects or momentum-based techniques like spatiotemporal modulation.
• Current momentum-based devices are limited to broadband or Lorentzian-shaped nonreciprocal frequency responses.

Purpose of the Study:

• To demonstrate a novel approach for creating devices with customizable nonreciprocal frequency responses.
• To overcome the limitations of existing nonreciprocal frequency response shapes.
• To establish a versatile platform for nonreciprocal systems adaptable to all wave phenomena.

Main Methods:

• Utilized nonreciprocal coupling between waveguide and resonator networks.
• Employed synthetic phonons to emulate propagating phonons, enabling light scattering between modes with different frequencies and momenta.
• Implemented nonreciprocal coupling in microstrip circuits for experimental validation.

Main Results:

• Successfully created devices with customizable nonreciprocal frequency responses.
• Experimentally demonstrated elementary nonreciprocal functions: isolation and gyration.
• Showcased reconfigurable, higher-order nonreciprocal filters.

Conclusions:

• Nonreciprocal coupling via synthetic phonons offers a powerful platform for designing advanced nonreciprocal devices.
• This method enables fine-tuning of frequency responses, surpassing previous limitations.
• The demonstrated approach is adaptable to diverse wave phenomena, promising broad applicability.