Invited Article: Narrowband terahertz bandpass filters employing stacked bilayer metasurface antireflection structures

• Main Authors: Chun-Chieh Chang, Li Huang, John Nogan, Hou-Tong Chen
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2018-05-01
• Series: APL Photonics
• Online Access: http://dx.doi.org/10.1063/1.5003984

We experimentally demonstrate high-performance narrowband terahertz (THz) bandpass filters through cascading multiple bilayer metasurface antireflection structures. Each bilayer metasurface, consisting of a square array of silicon pillars with a self-aligned top gold resonator-array and a complementary bottom gold slot-array, enables near-zero reflection and simultaneously close-to-unity single-band transmission at designed operational frequencies in the THz spectral region. The THz bandpass filters based on stacked bilayer metasurfaces allow a fairly narrow, high-transmission passband, and a fast roll-off to an extremely clean background outside the passband, thereby providing superior bandpass performance. The demonstrated scheme of narrowband THz bandpass filtering is of great importance for a variety of applications where spectrally clean, high THz transmission over a narrow bandwidth is desired, such as THz spectroscopy and imaging, molecular detection and monitoring, security screening, and THz wireless communications.