Optically Tunable Terahertz Metasurfaces Using Liquid Crystal Cells Coated with Photoalignment Layers

An optically tunable terahertz filter was fabricated using a metasurface-imbedded liquid crystal (LC) cell with photoalignment layers in this work. The LC director in the cell is aligned by a pump beam and makes angles theta of 0, 30, 60 and 90 degrees with respect to the gaps of the split-ring resonators (SRRs) of the metasurface under various polarized directions of the pump beam. Experimental results display that the resonance frequency of the metasurface in the cell increases with an increase in theta, and the cell has a frequency tuning region of 15 GHz. Simulated results reveal that the increase in the resonance frequency arises from the birefringence of the LC, and the LC has a birefringence of 0.13 in the terahertz region. The resonance frequency of the metasurface is shifted using the pump beam, so the metasurface-imbedded LC cell with the photoalignment layers is an optically tunable terahertz filter. The optically tunable terahertz filter is promising for applications in terahertz telecommunication, biosensing and terahertz imaging.

Automated summary

The study demonstrated the fabrication of an optically tunable terahertz filter using a metasurface-imbedded liquid crystal cell with photoalignment layers. Experimental results showed an increase in resonance frequency of the metasurface in the cell with the LC director angles, and a frequency tuning region of 15 GHz was achieved. Simulated results indicated the resonance frequency shift was due to the birefringence of the LC, with a value of 0.13 in the terahertz region. This optically tunable terahertz filter has potential applications in terahertz telecommunication, biosensing, and terahertz imaging.