Tunable band-stop fiber filter based on laser-induced graphene metamaterial in THz frequency

As an important device in the application of terahertz (THz) technology, a THz filter has broad application prospects in the fields of THz communication, imaging, and sensing. In this paper, a THz filter based on grating structure laser-induced graphene (LIG)/ side polishing terahertz fiber composite structure is proposed. In the experiment, we achieved the maximum Q factor of 23.83 at the central resonant frequency of 0.715 THz. By modifying the grating structure, a tunable operational span of 269 GHz was achieved, along with a tunable range of 21 GHz through laser stimulation. In testing, we found that LIG materials prepared with circular filling are more sensitive to relatively high-power pump lasers, while LIG samples prepared with line filling exhibit better linear response to laser power. Furthermore, the compact and highly integrated nature of the device suggests its broad potential utility in the realm of THz frequency selection.