Boosting the terahertz nonlinearity of graphene by orientation disorder

Abstract

Abstract. The conical band structure is the cornerstone of graphene's ultra-broadband optical conductivity. For practical use of graphene in nonlinear photonics, however, substantial increases of the light-matter interaction strength will be required while preserving the promising features of monolayers, as the interaction of light with a single atomic layer is limited due to the extremely short interaction length and low density of state, particularly for the long-wavelength region. Here, we report that this demand can be fulfilled by random stacking of high-quality large-area monolayer graphene up to a requested number of layers, which leads to the electronic interaction between layers being effectively switched off due to turbostratic disorder. The nonlinear characteristics of randomly stacked multilayer graphene (RSMG), which originates from a thermo-modulational feedback mechanism through ultrafast free-carrier heating and temperature-dependent carrier-phonon collisions, show clear improvements in the terahertz (THz) regime with increasing layer numbers, whereas as-grown multilayer graphene (AGMG) exhibits limited behaviors due to strong interlayer coupling. This controllable nonlinearity enhancement provides an ideal prerequisite for developing efficient graphene-based THz photonic devices.

Terahertz light-emitting graphene-channel transistor toward single-mode lasing

“…To break through these substantial limitations, graphene has attracted attention owing to its gapless and linear energy spectrum and massless Dirac Fermions, giving rise to superior carrier transport properties [27][28][29][30][31]. The latest studies have reported on the potential of relatively simpler multi-layer graphene devices [32,33] to more complex graphene/h-BN heterostructures [34,35] for highly sensitive detection as well as emission of THz radiation [35].…”

van der Waals Layered Tin Selenide as Highly Nonlinear Ultrafast Saturable Absorber

“…It was previously shown that the modulation depth of graphene could be significantly improved by the random stacking of layers with orientational disorder. This fact suggests that further enhancement of the absorption nonlinearity of SnSe could be possible if its layers are stacked with random orientation . The time‐bandwidth product of 0.397 indicates that the output pulses were slightly chirped in our laser system.…”

Terahertz wave modulation properties of graphene with different excitation laser power

“…Moreover, randomly stacked multilayer graphene can be treated as multiply electronically decoupled monolayer graphene. 30,31 The silicon prohibited bandwidth was 1.12 eV, while the silicon cutoff wavelength for its intrinsic leap was 1107 nm. We used a 975 nm CW laser as an excitation source to generate photo-generated carriers.…”