title: Giant two-photon absorption in bilayer graphene.
abstract: We present a quantum perturbation theory on two-photon absorption (2PA) in monolayer and bilayer graphene which is Bernal-stacked. The theory shows that 2PA is significantly greater in bilayer graphene than monolayer graphene in the visible and infrared spectrum (up to 3 μm) with a resonant 2PA coefficient of up to ∼0.2 cm/W located at half of the bandgap energy, γ(1) = 0.4 eV. In the visible and terahertz region, 2PA exhibits a light frequency dependence of ω(-3) in bilayer graphene, while it is proportional to ω(-4) for monolayer graphene at all photon energies. Within the same order of magnitude, the 2PA theory is in agreement with our Z-scan measurements on high-quality epitaxial bilayer graphene deposited on SiC substrate at light wavelength of 780 and 1100 nm.
authors.affiliation: Department of Physics, National University of Singapore, Singapore 117542.
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Yang
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Feng
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Han
authors.initials: H
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Andrew T S
authors.initials: AT
authors.lastname: Wee
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
mesh_terms: D006108:Graphite / Q000737:chemistry*; D036103:Nanotechnology; D017785:Photons; D011789:Quantum Theory
chemical_list: D006108:Graphite