A High-Selectivity THz Filter Based on a Flexible Polyimide Film

A frequency-selective, tunable terahertz (THz) filter based on a flexible tape is designed and characterized for a low-cost and easy-access THz filter with a wide range of center wavelengths (CWL) from 150 to 600 μm (2.0 to 0.5 THz). With more than 85% bandpass transmission and 10 dB bandstop reflection at the CWLs, the proposed filter based on metallic crossed-slot hole arrays are fabricated on a 50-μm polyimide film with low absorption and good mechanical properties, resulting in a large-area, free-standing, and flexible membrane with a low intrinsic loss. The frequency dependent characteristics of the filter are investigated by THz time-domain spectroscopy and excellent agreements between the measured and simulated results are demonstrated. The designed THz filter possesses not only a simple structure and polarization insensitivity, but also a light weight and high integration.