Speaker
Description
Controlling the phase and polarization of infrared light is essential for wavefront shaping and polarization conversion, yet achieving such control across the mid- and far-infrared (MIR–FIR) remains challenging: natural anisotropic optical materials are scarce in this range, and lossy plasmon polaritons alone offer limited control at longer infrared wavelengths. Here, we demonstrate infrared waveplates based on Au gratings on VO2/SiC (MIR) and SiO2/GaAs (FIR), in which coupled surface plasmon and phonon polaritons produce an anisotropic optical response. We characterize their polarization response with polarizer–analyzer reflection measurements and compare the results with numerical calculations. A Jones-calculus analysis relates the measured reflected intensities to the Stokes parameters, enabling direct extraction of the polarization-axis rotation and ellipticity spectra. Both spectra show resonant features that originate from Fabry–Pérot cavity resonances of the coupled polariton mode. Fitting a single-resonance Lorentzian response function yields maximum polarization rotations and ellipticities of 7.6° and 4.1° near 840 cm−1 for the SiC-based waveplate, and 2.8° and 1.4° near 276 cm−1 for the GaAs-based waveplate. These results demonstrate that hybrid plasmon–phonon resonances can enable compact waveplates, polarization converters, and wavefront-control devices throughout the infrared.
