Dual Tunable Electromagnetically Induced Transparency Based on a Grating-Assisted Double-Layer Graphene Hybrid Structure at Terahertz Frequencies

Abstract

We propose a graphene plasmonic structure by applying two graphene layers mingled with a thin gold layer in a silicon grating. By utilizing the finite-difference time-domain (FDTD) method, we investigate the optical response of the system, and observe that the design achieves dual tunable electromagnetically induced transparency (EIT)-like effect at terahertz frequencies. The EIT-like effect arises from the destructive interference between the grapheme-layer bright modes and the gold-layer dark mode. The EIT-like phenomenon can be adjusted by the Fermi level, which is related to the applied voltage. The results show that the group delay of the present structure reaches 0.62 ps in the terahertz band, the group refractive index exceeds 1200, the maximum delay-bandwidth product is 0.972, and the EIT-like peak frequency transmittance is up to 0.89. This indicates that the device has good slow light performance. The proposed structure might enable promising applications in slow-light devices.

Electronically triggered tunable terahertz signal observed in LPCVD grown single layer graphene

“…Another interesting phenomenon observed is the tuneable terahertz response of SLG under the application of varying external voltage. However, few theoretical and experimental studies on the THz signal of graphene are reported which are based on ultrafast electric field and gate voltage, 5 the optical response based on the grating assisted plasmonic structure of double layer graphene with a Au layer in between, 27 a tuneable THz wave modulator, 28 power dependent spectral characteristics of single layer graphene, 29 ultrafast photocurrent in dual-gated graphene using pump-probe spectroscopy and the thermoelectric effect, 30 variation in electrical conductivity of graphene on different substrates by THz signal mapping of graphene 31 and broadband graphene terahertz modulators enabled by intraband transitions. 32 To the best of our knowledge, no one has yet reported anywhere in the literature about the tuneable terahertz response of SLG under the application of varying external voltage.…”

Design and simulation of a compact graphene metamaterial sensor with high sensitivity based on electromagnetically induced transparency

“…In addition, the graphene layer is unnecessary for the patterning process, and it thus has great advantages in machinability and processing difficulty, which greatly improves the applicability of graphene. In 2022, Zhong et al 18 . proposed a graphene structure by applying two graphene layers mingled with a thin gold layer in a silicon grating and achieved a dual tunable EIT-like effect at terahertz frequencies.…”