On-demand polarization control of electromagnetic waves is the fundamental element of modern optics. Its interest has recently been expanded in the terahertz (THz) range for coherent excitation of collective quasiparticles in matters, triggering a wide variety of non-trivial intriguing physics, e.g., anharmonicity, nonlinear coupling, and metastability. Wavelength tunability in THz polarization control is fundamentally important for the resonant excitation of collective modes.