High Contrast, Femtosecond Light Polarization Manipulation in Epsilon-near-Zero Material Coupled to a Plasmonic Nanoantenna Array

Ultrafast manipulation of light polarization is crucial in many nonlinear optic and optoelectronic operations. However, most of the configurations are suffering from low modulation speed (gigahertz) or small contrast ratio. Here, by taking advantange of the anisotropic nonlinear response of indium tin oxide at its epsilon-near-zero region and plasmonic nanoantennas at their polarization-sensitive resonance, we achieve a large, ultrafast anisotropic modulation of light. A polarization elliptic rotation of 32.5° at 1.23 μm wavelength, and a phase delay between the oscillations of the linear polarization axes of π/7 within 600 fs response time is demonstrated. This approach constitutes a novel, efficient way to implement all-optical high-speed polarization modulators and retarders.