Abstract
Local phase control of electromagnetic wave, the basis of a diverse set of applications such as hologram imaging, polarization and wave-front manipulation, is of fundamental importance in photonic research. However, the bulky, passive phase modulators currently available remain a hurdle for photonic integration. Here we demonstrate full-range active phase modulations in the Tera-Hertz (THz) regime, realized by gate-tuned ultra-thin reflective metasurfaces based on graphene. A one-port resonator model, backed by our full-wave simulations, reveals the underlying mechanism of our extreme phase modulations, and points to general strategies for the design of tunable photonic devices. As a particular example, we demonstrate a gate-tunable THz polarization modulator based on our graphene metasurface. Our findings pave the road towards exciting photonic applications based on active phase manipulations.
Highlights
The phase modulation of electromagnetic (EM) waves is crucial in photonics research
We propose a new mechanism to achieve a wide phase modulation range, with graphene used as a tunable loss to drive an underdamped to overdamped resonator transition
We show that a gate bias applied to graphene through an ion liquid tunes its optical conductivity, transforms the coupled system from an underdamped resonator to an overdamped one, and drastically modulates the phase of the reflected wave
Summary
The phase modulation of electromagnetic (EM) waves is crucial in photonics research. This is best exemplified by the Huygens principle: A far-field EM wave front is essentially determined by the phase distribution in a given near-field plane [1]. Tunable Terahertz Phase Modulation with Gate-Controlled Graphene Metasurfaces We propose a new mechanism to achieve a wide phase modulation range, with graphene used as a tunable loss to drive an underdamped to overdamped resonator transition.
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