Ultrafast control of the polarization state of light may enable a plethora of applications in optics, chemistry and biology. However, conventional polarizing elements, such as polarizers and waveplates, are either static or possess only gigahertz switching speeds. Here, with the aid of high-mobility indium-doped cadmium oxide (CdO) as the gateway plasmonic material, we realize a high-quality factor Berreman-type perfect absorber at a wavelength of 2.08 μm. On sub-bandgap optical pumping, the perfect absorption resonance strongly redshifts because of the transient increase of the ensemble-averaged effective electron mass of CdO, which leads to an absolute change in the p-polarized reflectance from 1.0 to 86.3%. By combining the exceedingly high modulation depth with the polarization selectivity of the perfect absorber, we experimentally demonstrate a reflective polarizer with a polarization extinction ratio of 91 that can be switched on and off within 800 fs.

中文翻译：

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飞秒光偏振切换，使用基于氧化镉的完美吸收剂

对光的偏振态的超快控制可以在光学，化学和生物学领域实现大量应用。然而，诸如偏振片和波片之类的常规偏振元件要么是静态的，要么仅具有千兆赫兹的切换速度。在此，借助于高迁移率的铟掺杂氧化镉（CdO）作为网关等离激元材料，我们实现了波长为2.08μm的高质量因子Berreman型完美吸收体。在亚带隙光泵浦中，由于CdO的集合平均有效电子质量的瞬时增加，理想吸收共振会强烈红移，从而导致p的绝对变化偏振反射率从1.0到86.3％。通过将极高的调制深度与完美吸收体的偏振选择性相结合，我们实验证明了一种反射消光器，其消光比为91，可以在800 fs内打开和关闭。