Zhang Chi, Shen Suling, Wang Qiong, Lin Mi, Ouyang Zhengbiao, Liu Qiang
THz Technical Research Center, Shenzhen University, Shenzhen 518060, China.
College of Physics & Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Materials (Basel). 2020 Mar 8;13(5):1217. doi: 10.3390/ma13051217.
THz waves have interesting applications in refractive index sensing. A THz gas sensor based on the guided Bloch surface wave resonance (GBSWR) in a one-dimensional photonic crystal (1DPhC), which consists of periodic polycarbonate (PC) layers and polyvinylidene fluoride (PVDF) layers, has been proposed. Numerical results based on finite element method (FEM) show that the photonic band gap that confines Bloch surface waves (BSWs) lies in the regime of 11.54 to 21.43 THz, in which THz wave can transmit in both PC and PVDF with the ignored absorption. The calculated sensitivity of hazardous gas HCN in angle is found to be 118.6°/RIU (and the corresponding figure of merit (FOM) is 227) and the sensitivity in frequency is 4.7 THz/RIU (the corresponding FOM is 301.3). The proposed structure may also be used for monitoring hazardous gases which show absorption to the incident THz wave. Further results show that for NO gas, the maximum sensitivity goes up to 644 (transmittance unit/ one unit of the imaginary part of the refractive index). The proposed design may find applications in the detection of dangerous gases.
太赫兹波在折射率传感方面有着有趣的应用。一种基于一维光子晶体（1DPhC）中导波布洛赫表面波共振（GBSWR）的太赫兹气体传感器被提了出来，该一维光子晶体由周期性的聚碳酸酯（PC）层和聚偏氟乙烯（PVDF）层组成。基于有限元方法（FEM）的数值结果表明，限制布洛赫表面波（BSWs）的光子带隙处于11.54至21.43太赫兹范围内，在该范围内太赫兹波可以在聚碳酸酯和聚偏氟乙烯中传播，且吸收可忽略不计。计算得出危险气体HCN在角度上的灵敏度为118.6°/RIU（相应的品质因数（FOM）为227），在频率上的灵敏度为4.7太赫兹/RIU（相应的FOM为301.3）。所提出的结构还可用于监测对入射太赫兹波有吸收的危险气体。进一步的结果表明，对于NO气体，最大灵敏度高达644（透过率单位/折射率虚部的一个单位）。所提出的设计可能在危险气体检测中找到应用。
