Versatile and active THz wave polarization modulators using metamaterial/graphene resonators

Active modification of the polarization state is a key feature for the next-generation of wireless communications, sensing, and imaging in the THz band. The polarization modulation performance of an integrated metamaterial/graphene device is investigated via a modified THz time domain spectroscopic system. Graphene's Fermi level is modified through electrostatic gating, thus modifying the device's overall optical response. Active tuning of ellipticity by > 0.3 is reported at the resonant frequency of 0.80 THz. The optical activity of transmitted THz radiations is continuouslymodified by > 21.5 degrees at 0.71 THz. By carefully selecting the transmitted frequency with the relative angle between the incoming linear polarization and the device's symmetry axis, active circular dichroism and optical activity are almost independently exploited. Finally, this all-electronically tuneable versatile polarization device can be used in all applications requiring an ultrafast modulation such as polarization spectroscopy, imaging, and THz wireless generation.

Automated summary

The study investigates the polarization modulation performance of an integrated metamaterial/graphene device in the THz band. By modifying the graphene's Fermi level, the device's optical response can be modified, enabling active tuning of ellipticity and continuous modification of optical activity. Active circular dichroism and optical activity can be independently exploited by carefully selecting the transmitted frequency and relative angle between the incoming linear polarization and the device's symmetry axis. This all-electronically tuneable versatile polarization device has potential applications in polarization spectroscopy, imaging, and THz wireless generation.