Broadband THz bandpass filters based on multi-layered metasurfaces

We present a terahertz (THz) bandpass filter design based on four superimposed metasurfaces. The devices feature a spectral transmission with a flat passband region at T=0.65 and a stopband rejection larger than ~40dB. The two regions are separated by steep roll-offs with a slope of 85 dB/octave. Because of their unique filtering properties, these devices enable new applications for weak signal detection in THz research and industry.