Exploring nonlinear optical properties of graphene from microwave to mid-infrared frequencies
Technical Report,15 May 2015,14 May 2018
Texas A and M University College Station United States
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Six projects supported by the award were completed. 1 A rigorous quantum-mechanical theory of the second-order nonlinear response of two-dimensional 2D massless Dirac fermions in graphene and topological insulators has been developed. The resulting nonlinear susceptibility tensor satisfies all symmetry and permutation properties with respect to its indices and arguments, is gauge-invariant, and has a correct quasiclassical limit for low frequencies. 2 A new optical mechanism of spin-valley entanglement of excitons in transition metal dichalcogenide monolayers has been proposed. 3 A theory of the third-order nonlinearity of 2D electron gas in coupled quantum well systems has been developed and applied to the four-wave mixing and phase locking of laser modes in quantum cascade lasers QCLs. The collaborators at Sheffield experimentally demonstrated active mode locking of mid-infrared QCLs. 4 In the presence of a magnetic field, a nonperturbative theory for 2D magnetoexcitons interacting with terahertz radiation has been developed and applied to explain the striking stability of 2D magnetoexcitons against dissociation the absence of the Mott transition at high magnetic fields. 5 A strong enhancement of both spontaneous emission and nonlinear optical response of graphene and other 2D materials in subwavelength 2D cavities has been predicted and applied to the design of nonlinear photonic circuits. 6 The optical response and electrodynamic properties of massless Dirac fermions in Dirac and Weyl semimetals in a magnetic field have been investigated. The results indicate that Weyl semimetals can serve as efficient polarizers, light modulators, and natural hyperbolic materials in the terahertz THz and infrared spectral ranges, with applications in ultracompact photonic chips. Projects 1 through 4 have been described in previous reports. Here we focus on projects 5 and 6.
- Nuclear Physics and Elementary Particle Physics
- Quantum Theory and Relativity
- Operations Research