Terahertz liquid crystal suspended core photonic crystal fiber polarization rotator

•Tunable suspended core THz PCF polarization rotator (PR) is reported.•By applying an external voltage, the polarization conversion ratio can be adjusted.•At a device length of 2023 µm and f = 0.6 THz, polarization conversion ratio of 99 % is attained with crosstalk of −19.76 dB.•The crosstalk is better than −10 dB within a tolerance of ±0.1 THz around the operating frequency. Tunable suspended core photonic crystal fiber (SC-PCF) is designed and investigated as a polarization rotator (PR) in the Terahertz (THz) band. In the proposed THz-SC-PCF-PR device, the backgrounds used are the air and TOPAS polymer. In order to enhancing the modal hybridity of the two polarized modes, the nematic liquid crystal (NLC) is used to increase the polarization conversion ratio. So, the core is filled with NLC type E7 material in the proposed THz-SC-PCF-PR design. Furthermore, the conversion ratio of the polarization can be adjusted by applying an external voltage. The modal and propagation analysis of the THz-SC-PCF-PR is studied using full vectorial finite difference approach. To reduce the device length while maintaining low crosstalk, the geometrical parameters are studied. At a conversion length of 2023 µm and a frequency of 0.6 THz, high conversion ratio of 99 % is attained with a minimum crosstalk of −19.76 dB. Furthermore, crosstalk is still less than −10 dB at a 0.1 THz bandwidth around the working frequency. Further, the proposed THz-SC-PCF-PR has a good fabrication tolerance for the geometrical parameters and temperature, ensuring the described design's viability in the THz domain.