We study a polarizer-analyzer mounting for the terahertz regime with perfectly conducting metallic polarizers made of a periodic subwavelength pattern. We analytically investigate the influence on the transmission response of the multiple reflections which occur between polarizer and analyzer with a renewed Jones formalism. We demonstrate that this interaction leads to a modified transmission response: the extended Malus' Law. In addition, we show that the transmission response can be controlled by the distance between polarizer and analyzer. For particular set-ups, the mounting exhibits extremely sensitive transmission responses. This interesting feature can be employed for high precision sensing and characterization applications. We specifically propose a general design for measuring electro-optical response of materials in the terahertz domain allowing detection of refractive index variations as small as 10 −5 .
All-electronicultrafast control of terahertz radiation is demonstrated in integrated metamaterial/graphene devices. By electrostatic gating the graphene conductivity, the overall optical response of the incident terahertz E-field is modified. Depending on the configuration, amplitude, phase, and polarization of terahertz radiation could be modulated with GHz range of reconfiguration speed. An extinction ratio of >7.6 dB in amplitude is achieved at the resonant frequency of 0.75 THz. Additionally, a relative phase shift of >17.4 • is observed around a frequency of 0.68 THz. When operating as a polarization modulator, the device has reported an ellipticity change of ∼ 40% at a frequency of 0.68 THz and a dynamic rotation of the polarization plane by >9 • at resonance. The switching capability of the modulators has been investigated all electronically reporting a speed exceeding 3 GHz, only limited by the available instrumentation. Consequently, GHzspeed of modulation can be achieved for frequencies around 0.75 THz. These results represent a breakthrough for all applications where a fast, versatile, and efficient modulation of THz radiation is required, such as in next-generation wireless communication, quantum electronics, and ultrafast imaging.
Stacked metasurfaces are being investigated in light of exploring exotic optical effects that cannot be achieved with single-layered metasurfaces. In this article, we theoretically demonstrate that metallic wire-grid metasurfaces with specific polarization properties have the ability to induce tunable Fano resonances when they are stacked. The developed original model—combining a circulating field approach together with an extended Jones formalism—reveals the underlying principle that gives rise to the polarization-induced Fano resonances. The theoretical frame is validated in an experimental proof of concept using commercially available wire-grids and a terahertz time domain spectrometer. This unexplored possibility opens an alternative path to the realization and control of Fano resonances by using stacked metallic metasurfaces. Furthermore, these findings suggest that the polarization can be used as an additional degree of freedom for the design of optical resonators with enhanced and tunable properties.
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