Department of Micro and Nanosystems, KTH Royal Institute of Technology, Osquldas väg 10, SE-100 44, Stockholm, Sweden.
Nanoscale. 2018 Jul 9;10(26):12291-12296. doi: 10.1039/c8nr03740j.
Materials with tunable dielectric properties are valuable for a wide range of electronic devices, but are often lossy at terahertz frequencies. Here we experimentally report the tuning of the dielectric properties of single-walled carbon nanotubes under light illumination. The effect is demonstrated by measurements of impedance variations at low frequency as well as complex dielectric constant variations in the wide frequency range of 0.1-1 THz by time domain spectroscopy. We show that the dielectric constant is significantly modified for varying light intensities. The effect is also practically applied to phase shifters based on dielectric rod waveguides, loaded with carbon nanotube layers. The carbon nanotubes are used as tunable impedance surface controlled by light illumination, in the frequency range of 75-500 GHz. These results suggest that the effect of dielectric constant tuning with light, accompanied by low transmission losses of the carbon nanotube layer in such an ultra-wide band, may open up new directions for the design and fabrication of novel Terahertz and optoelectronic devices.
具有可调介电性能的材料对于各种电子设备非常有价值，但在太赫兹频率下通常是有损耗的。在这里，我们通过实验报告了单壁碳纳米管在光照射下介电性能的可调谐。通过低频阻抗变化的测量以及时域光谱在 0.1-1THz 的宽频率范围内的复介电常数变化，证明了这种效应。我们表明，介电常数随光强的变化而显著改变。该效应还实际应用于基于介质棒波导的相移器，其中加载了碳纳米管层。碳纳米管用作由光照射控制的可调谐阻抗表面，工作频率范围为 75-500GHz。这些结果表明，伴随着碳纳米管层在如此超宽带中的低传输损耗的介电常数调谐效应，可能为新型太赫兹和光电设备的设计和制造开辟新的方向。
