摘要
The realization of high-performance tunable absorbers for terahertz frequencies is crucial for advancing applications such as single-pixel imaging and spectroscopy.Based on the strong position sensitivity of metamaterials’electromagnetic response,we combine meta-atoms that support strongly localized modes with suspended flat membranes that can be driven electrostatically.This design maximizes the tunability range for small mechanical displacements of the membranes.We employ a micro-electromechanical system technology and successfully fabricate the devices.Our prototype devices are among the best-performing tunable THz absorbers demonstrated to date,with an ultrathin device thickness(~1/50 of the working wavelength),absorption varying between 60%and 80%in the initial state when the membranes remain suspended,and fast switching speed(~27μs).The absorption is tuned by an applied voltage,with the most marked results achieved when the structure reaches the snap-down state.In this case,the resonance shifts by >200% of the linewidth(14% of the initial resonance frequency),and the absolute absorption modulation measured at the initial resonance can reach 65%.The demonstrated approach can be further optimized and extended to benefit numerous applications in THz technology.
