Experimental realization of a full-band wave antireflection based on temporal taper metamaterials

As time can be introduced as an additional degree of freedom, temporal metamaterials nowadays open up new avenues for wave control and manipulation. Among these advancements, temporal metamaterial-based antireflection coatings have recently emerged as an innovative method that inherently avoids additional spatial insertions. However, prior temporal antireflection models with finite inserted temporal transition sections that rely on the destructive interference mechanism exhibit residual periodic strong reflections at high frequencies, fundamentally limiting the achievable bandwidth. In this work, the concept of “temporal taper”, the temporal counterpart of a conventional spatial taper with a nearly full-band antireflection feature and good compatibility with gradual time-varying components, has been experimentally realized. A 1D temporal metamaterial based on voltage-controlled varactors has been designed and experimentally validated. The temporal taper based broadband antireflection exempts the system from spatial matching insertions, and enables agile impedance matching for various terminal loads, positioning it as a promising approach in future photonic systems. Temporal metamaterials enable wave control through timevarying properties, but achieving broadband antireflection remains challenging. Here, the authors experimentally realize a “temporal taper” metamaterial that provides near-full-band antireflection, eliminating the need for spatial matching components and enabling agile impedance matching.