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Nonlocal and Nonlinear Plasmonics in Atomically Thin Heterostructures
A new theoretical study published in ACS Nano shows how interactions between electrically tunable graphene and phosphorene nanoribbons can be used to control and selectively enhance nonlinear optical processes at the nanoscale.
In this newly released publication, Assistant Professor Line Jelver and Professor Joel D. Cox investigate how plasmons—collective oscillations of electrons that can confine light far below its wavelength—interact in pairs of closely spaced graphene and phosphorene nanoribbons. Using atomistic simulations based on first-principles electronic-structure calculations, the researchers capture quantum finite-size and nonlocal effects that become important in such sub 10 nanometre geometries.
The study demonstrates how optical nonlocality can become a useful resource for nonlinear optics. By varying the ribbon material, width, edge termination, relative arrangement and electrical doping, the plasmon modes of neighbouring ribbons can be made to hybridize, strongly reshaping the optical fields between them. This interaction provides several independent ways of controlling nonlinear optical processes. In particular, the rapidly varying near-fields can break the effective symmetry of the optical response and enable second-harmonic generation, in which incoming light is converted to twice its original frequency.
The researchers additionally investigate the response to intense ultrashort optical pulses. Graphene, phosphorene and combined graphene–phosphorene structures are predicted to produce rich high-harmonic spectra, generating light at several multiples of the incoming frequency. Rather than enhancing every harmonic equally, different combinations of material, geometry and electrical doping is shown to either enhance or distinguish specific harmonic orders.
Together, the results provide design principles for compact and electrically reconfigurable nonlinear optical components based on atomically thin materials. Such structures offer multiple ways to tailor nanoscale light–matter interactions and to control light with light through material selection, structural design and electrostatic gating.
Link to publication: Nonlocal and Nonlinear Plasmonics in Atomically Thin Heterostructures, DOI: 10.1021/acsnano.5c20758
The study demonstrates how optical nonlocality can become a useful resource for nonlinear optics. By varying the ribbon material, width, edge termination, relative arrangement and electrical doping, the plasmon modes of neighbouring ribbons can be made to hybridize, strongly reshaping the optical fields between them. This interaction provides several independent ways of controlling nonlinear optical processes. In particular, the rapidly varying near-fields can break the effective symmetry of the optical response and enable second-harmonic generation, in which incoming light is converted to twice its original frequency.
The researchers additionally investigate the response to intense ultrashort optical pulses. Graphene, phosphorene and combined graphene–phosphorene structures are predicted to produce rich high-harmonic spectra, generating light at several multiples of the incoming frequency. Rather than enhancing every harmonic equally, different combinations of material, geometry and electrical doping is shown to either enhance or distinguish specific harmonic orders.
Together, the results provide design principles for compact and electrically reconfigurable nonlinear optical components based on atomically thin materials. Such structures offer multiple ways to tailor nanoscale light–matter interactions and to control light with light through material selection, structural design and electrostatic gating.
Link to publication: Nonlocal and Nonlinear Plasmonics in Atomically Thin Heterostructures, DOI: 10.1021/acsnano.5c20758