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Adsorption of two representative anionic dyes (Acid Fuchsine (AF) and Acid Orange II (AO)) using MCM-41 functionalized with amine groups in a mesoporous silica framework (NH2–MCM-41) as the adsorbent was investigated.

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The conductivity of poly(3,4-ethylene dioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) is significantly enhanced on adding some organic solvent such as ethylene glycol (EG). In this paper, the optoelectronic properties of EG doped PEDOT/PSS on transmission and anti-reflection effects are investigated in detail by terahertz time domain spectroscopy (THz-TDS). The transmission line circuit theory gives us an insight into the THz transmission mechanisms of the main and second pulses. In particular, we show that the conductivities of 10% EG doped PEDOT/PSS are nearly frequency independent from 0.3 to 1.5 THz. To demonstrate applications of this property, we design and fabricate broadband terahertz neutral density filters and anti-reflection coatings based on 10% EG doped PEDOT/PSS thin films with varying thickness. Our measurements highlight the capability of THz-TDS to characterize the conductivity of EG doped PEDOT/PSS, which is essential for broadband optoelectronic devices in THz region.

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Coding metasurfaces have emerged as a promising venue for terahertz (THz) beam steering and beamforming. In this study, we designed a transmission metasurface with a complementary structure based on Babinet's principle. The beam-steering capability of the coding metasurface is implemented by encoding “0” and “1” elements with different phase responses and by controlling the coding sequences. The deflection angle can be controlled by changing the period of these 0 and 1 elements. Despite the development of beam-steering technology, measurements of the direction pattern of steered THz beams remain challenging. Systems for THz time-domain spectroscopy and spectral imaging are used to characterize the flexible coding metasurfaces. The THz imaging system can provide information on the directional pattern of the beam. To verify the performance of the proposed metasurface, the experimental measurements of beam deflection were found to be consistent with the values yielded by a simulation. Our study provides an effective platform for the design and measurement of THz beam steering.