Electrical Control of Second-Harmonic Generation in a WSe2 Monolayer Transistor

Abstract

Nonlinear optical frequency conversion, in which optical fields interact with a nonlinear medium to produce new field frequencies, is ubiquitous in modern photonic systems. However, the nonlinear electric susceptibilities that give rise to such phenomena are often challenging to tune in a given material, and so far, dynamical control of optical nonlinearities remains confined to research labs as a spectroscopic tool. Here, we report a mechanism to electrically control second-order optical nonlinearities in monolayer WSe2, an atomically thin semiconductor. We show that the intensity of second-harmonic generation at the A-exciton resonance is tunable by over an order of magnitude at low temperature and nearly a factor of 4 at room temperature through electrostatic doping in a field-effect transistor. Such tunability arises from the strong exciton charging effects in monolayer semiconductors, which allow for exceptional control over the oscillator strengths at the exciton and trion resonances. The exciton-enhanced second-harmonic generation is counter-circularly polarized to the excitation laser, arising from the combination of the two-photon and one-photon valley selection rules that have opposite helicity in the monolayer. Our study paves the way towards a new platform for chip-scale, electrically tunable nonlinear optical devices based on two-dimensional semiconductors.

Published in Nature Nanotechnology

References in corpus (10)

• Valley polarization in MoS2 monolayers by optical pumping
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Tightly bound excitons in monolayer WSe2
• Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Exciton Binding Energy of Monolayer WS2
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• Coupling the valley degree of freedom to antiferromagnetic order
• Electrical Control of Optical Properties of Monolayer MoS${}_2$
• Intervalley coupling by quantum dot confinement potentials in monolayer transition metal dichalcogenides

Cited by in corpus (15)

• Optical imaging of strain in two-dimensional crystals
• Optical response of monolayer, few-layer and bulk tungsten disulfide
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
• Optical spectroscopy of excited exciton states in MoS2 monolayers in van der Waals heterostructures
• Electric-field switchable second-harmonic generation in bilayer MoS${}_2$ by inversion symmetry breaking
• Intrinsic exciton states mixing and non-linear optical properties in transition metal dichalcogenide monolayers
• Electroabsorption in MoS${}_2$
• Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
• Phase matched nonlinear optics via patterning layered materials
• Scalable Transfer-Free Fabrication of MoS${}_2$/SiO${}_2$ Hybrid Nanophotonic Cavity Arrays with Quality Factors Exceeding 4000
• Quantum interference between the optical Stark effect and resonant harmonic generation in WS2
• Layer Tunable Third-Harmonic Generation in Multilayer Black Phosphorus
• Pressure-controlled Structural Symmetry Transition in Layered InSe
• Parametrically Excited Time-varying Metasurfaces for Second Harmonic Generation
• Nonlinear optics in the electron-hole continuum in 2D semiconductors: two-photon transition, second harmonic generation and valley current injection