Electrolyte gated graphene terahertz amplitude modulators
Syed Muhammad Abouzar Sarfraz, Alessandra Di Gaspare, Miriam S. Vitiello, Gaetano Scamarcio
Abstract
Active manipulation of the amplitude of terahertz (THz) frequency waves, through electrical tuning, is key for next-generation THz imaging and essential for unlocking strategic applications, from wireless communication to quantum technologies. Here, we demonstrate high-performance THz amplitude modulators based on an electrolyte-gated single-layer graphene. Broadband modulation in the 1.5–6 THz range is achieved by optimizing the electric field coupling by carefully controlling the spacer thickness in a quarter-wavelength cavity structure, with a maximum modulation depth of 40% at around 2 THz. Raman characterization confirms a Fermi-level tuning of 0.39 eV via electrolyte gating of graphene. A test 2 × 2 modulator array with independent control of sub-millimeter regions is then developed and tested, with no crosstalk between pixels. The reported results highlight the potential of electrolyte-gated graphene for efficient THz modulation. The single-chip design offers compactness and ease of integration with other electronic components, making it a promising platform for THz spatial light modulators and adaptive optical components.