Achieving bi-anisotropic coupling through uniform temporal modulations without inversion symmetry disruption.

Temporal modulations provide a new approach for realizing metamaterials. In this study, through the imposition of uniform temporal modulations, we achieve two types of reciprocal bi-anisotropic metamaterials. Notably, these achievements do not rely on any spatial modulation, preserving inversion symmetry at any instantaneous time.

Nonlocal effective medium theory for phononic temporal metamaterials.

We have developed a nonlocal effective medium theory (EMT) for phononic temporal metamaterials using the multiscale technique. Our EMT yields closed-form expressions for effective constitutive parameters and reveals these materials as reciprocal media with symmetric band dispersion. Even without spatial symmetry breaking, nonzero Willis coupling coefficients emerge with time modulation and broken time-reversal symmetry, when the nonlocal effect is taken into account.

Lorentzian dispersive antireflection temporal coatings with multiple time durations.

As the temporal counterparts of traditional antireflection coatings, antireflection temporal coatings (ATCs) provide a novel approach to eliminate reflections by employing two-step temporal modulations. The interval between these two temporal modulation steps is called the time duration of the ATC. In this Letter, we explore ATCs utilizing Lorentzian dispersive media through an extended temporal transfer matrix method, and we discover that they exhibit diverse time durations and offer the potential for enhanced transmission.