Origin and MATLAB can be used to plot the files. “Figure2” contains the effective refractive index, propagation distance, and mode confinement at different gap heights for different gap widths” (BOOK1). “Figure3” includes the effective refractive index, propagation distance, and mode confinement of THz plasmonic waveguide at different frequencies as a function of temperature (BOOK1), and the permittivity of the superconducting thin film at different frequencies as a function of temperature (BOOK2). “Figure4” contains the dispersion curve of the THz plasmonic waveguide for different temperatures as well as light line dispersion (BOOK1), and electric field distribution above the waveguide in different temperatures (BOOK2). “Figure A1” contains the mode confinement and propagation distance as a function f temperature for superconducting and gold plasmonic waveguides (BOOK1). “Figure A2” contains the absorption coefficient of superconducting plasmonic waveguides as a function of temperature at different frequencies (BOOK1), and the absorption coefficient of the gold plasmonic waveguide as a function of frequency (BOOK2). For full theoretical calculation, please refer to the main publication.