Bark Hyeon Sang, Park Mun-Won, Baek In Hyung, Jang Kyu-Ha, Jeong Young Uk, Lee Kitae, Jeon Tae-In
Opt Express. 2022 Feb 28;30(5):7976-7986. doi: 10.1364/OE.452064.
We propose an all-dielectric single-layer guided-mode resonance filter (GMRF) operating in the high-frequency terahertz (THz) region. For the fabrication of thin gratings to achieve strong resonance in the high-frequency region, the refractive index and absorption must be small, while the tensile strength must be high. Cyclic olefin copolymer (COC) films have a lower refractive index and absorption than polyethylene terephthalate (PET) films and a higher tensile yield strength than polytetrafluoroethylene (PTFE) films. Therefore, the COC film was found suitable to fabricate a GMRF operating in the high-frequency THz region. We fabricated COC-based single-layer GMRFs with a thickness of 50 µm and grating periods of 500, 400, 300, 200, and 100 µm; the resonance frequencies of the TE mode were 0.576, 0.712, 0.939, 1.329, and 2.759 THz, respectively. A shorter grating period caused a greater shift of the resonance to a higher frequency. In particular, the COC film enabled the fabrication of a 100-µm grating period with a ridge width of 32 µm and length of 2 mm, enabling the GMRF to operate up to 2.759 THz, which is very high frequency compared to the previous highest frequency of 0.7 THz. These results were in good agreement with a simulation using rigorous coupled-wave analysis.
我们提出了一种工作在高频太赫兹（THz）波段的全介质单层导模共振滤波器（GMRF）。为了制造能在高频区域实现强共振的薄光栅，其折射率和吸收率必须小，而拉伸强度必须高。环烯烃共聚物（COC）薄膜的折射率和吸收率低于聚对苯二甲酸乙二酯（PET）薄膜，拉伸屈服强度高于聚四氟乙烯（PTFE）薄膜。因此，发现COC薄膜适合制造工作在高频THz区域的GMRF。我们制造了厚度为50 µm、光栅周期分别为500、400、300、200和100 µm的基于COC的单层GMRF；TE模式的共振频率分别为0.576、0.712、0.939、1.329和2.759 THz。较短的光栅周期会使共振向更高频率发生更大的偏移。特别是，COC薄膜能够制造出光栅周期为100 µm、脊宽为32 µm、长度为2 mm的结构，使GMRF能够工作到2.759 THz，与之前的最高频率0.7 THz相比，这是非常高的频率。这些结果与使用严格耦合波分析的模拟结果非常吻合。
