We propose and numerically analyze a kind of terahertz (THz) phase-shifted gratings based on circularly symmetrical subwavelength waveguides. The filtering principle lies in that through introducing periodically structural disturbance to the subwavelength dielectric wire along the THz wave propagation direction, the coupling response are inspired. By modifying the central period unit to introduce a π shift, a THz phase-shifted grating which can operate as a narrowband pass filter is realized. The extinction ratio (ER) and full-width half-maximum (FWHM) of the phase-shifted grating that offers narrow transmission peak are 12.8 dB and FWHM of 2.0 GHz, respectively. Thanks to the circularly symmetrical structure of the waveguides, the proposed gratings are polarization insensitive. Moreover, the application of phase-shifted grating in refractive index sensing is also investigated. The proposed gratings may pave the way for various applications in compact and robust THz sensing, imaging, and communication systems.

我们提出并数值分析一种基于圆对称亚波长波导的太赫兹（THz）相移光栅。滤波原理在于，通过沿太赫兹波传播方向周期性地向亚波长电介质线引入结构扰动，激发了耦合响应。通过修改中心周期单元以引入π位移，实现了可以用作窄带通滤波器的太赫兹相移光栅。提供窄传输峰值的相移光栅的消光比（ER）和全宽半最大值（FWHM）分别为12.8 dB和2.0 GHz的FWHM。由于波导的圆对称结构，所提出的光栅对偏振不敏感。此外，还研究了相移光栅在折射率传感中的应用。所提出的光栅可以为紧凑而坚固的太赫兹感测，成像和通信系统中的各种应用铺平道路。