On the specially designed fractal metasurface-based dual-polarization converter in the THz regime

•Specially designed fractal metasurface-based structure is proposed to operate as a dual-polarization converter.•The converter has the ability to perform both the linear-to-cross (LX) and linear-to-circular (LC) polarization conversions.•The effect of oblique incidence on the performance of converter is studied.•The converter exhibits fairly stable operation in the THz regime.•The obtained results indicate the proposed converter to have possible potentials in imaging, antenna engineering etc. A specially designed fractal metasurface-based structure was investigated as a dual-polarization converter operating in the terahertz (THz) band. The proposed converter has the ability to perform both the linear-to-cross (LX) and linear-to-circular (LC) polarization conversions. In the former kind of operation, it exhibits three unity polarization conversion ratio (PCR) peaks at 1.10 THz, 2.13 THz and 3.46 THz frequencies, whereas in the latter situation, the conversion was achieved over three operating bands, namely 1.2–1.83 THz, 2.52–3.10 THz and 3.78–3.90 THz. The effect of oblique incidence on the performance of metasurface (used in designing the converter) was also studied, and fairly stable operation could be determined. The obtained results indicate the proposed converter to have possible potentials in imaging, antenna engineering and certain other photonic devices used in the fields of medical diagnostics, sensing, and other related measurements.