Terahertz graphene modulator based on hybrid plasmonic waveguide

Abstract

As a key component of on-chip interconnection, optical modulator with large modulation depth and tiny footprint has always been studied. Profiting by high carrier mobility and flexible adjustability of graphene, numerous graphene modulators at optical communication band are proposed to overcome inherent flaws of traditional semiconductor waveguide modulators. Here, a terahertz waveguide modulator combing noble metal and graphene is presented. When Fermi level changes from 0 eV to 1 eV, intensity distribution of electric field becomes dispersed. Interaction area of graphene and wave increases, which results in larger propagation loss. On the premise of the existence of the allowed mode, the size of metal and the thickness of dielectric should be small. Besides, modulation capability of this device can also be improved by multilayer graphene with relaxation time of 0.1 ps. After optimizing structure parameters, the designed graphene waveguide modulator obtains modulation depth of 6.1 dB μm−1 at the frequency of 5 THz, and keeps effective mode area below 10−5. With the increase of frequency, modulation depth decreases. Modulation depth of 1.5 dB μm−1 is achieved at 10 THz, but the corresponding effective mode area remains in an ideal range. Because the allowed mode is confined in a tiny room, cross-sectional area of device is less than 4 μm2.

Multifunctional THz Graphene Antenna with 360∘ Continuous ϕ-Steering and θ-Control of Beam

“…By defining the surface impedance boundary condition appropriately, the simulation can accurately model the electromagnetic behavior of the thin graphene sheet and the antenna and can predict the performance of the device. The chosen graphene parameters are ps [ 52 , 53 ] and room temperature K. As an optimization starting point for defining the device dimensions, the pre-optimization dimensions formerly calculated for the graphene dipole antenna were used ( and ). Then, reflectors were included in the model.…”

Hybrid Nanowire–Rectangular Plasmonic Waveguide for Subwavelength Confinement at 1550 Nm

“…The hybrid waveguide consists of two Ag nanowires and a conventional Si waveguide structure. The entire structure is filled with SiO 2 cladding, which acts as a low exponential gap between Si and Ag [ 23 ]. Excellent waveguide characteristics were obtained as a result of the double-mode coupling of Ag and Si in this structure.…”

Investigating the impact of polarization on surface plasmon polariton characteristics in plasmonic waveguides under periodic driving fields

“…Numerous mechanisms have been proposed in the literature to enhance and manipulate the propagation properties in SPP waveguides [44][45][46][47][48]. Some of these include the utilization of metamaterials or nanostructured materials [49,50] and innovative concepts such as plasmon-induced transparency [51][52][53]. However, the improvements in propagation length are constrained by various system parameters, including waveguide geometry, operating frequency, and implementation considerations.…”