Efficient Frequency Mixing of Guided Surface Waves by Atomically Thin Nonlinear Crystals

Abstract

Monolayer transition metal dichalcogenides possess considerable second-order nonlinear coefficients but a limited efficiency of frequency conversion due to the short interaction length with light under the typical direct illumination. Here, we demonstrate an efficient frequency mixing of the guided surface waves on a monolayer tungsten disulfide (WS 2 ) by simultaneously lifting the temporal and spatial overlap of the guided wave and the nonlinear crystal. Three orders-of-magnitude enhancement of the conversion efficiency was achieved in the counter-propagating excitation configuration. Also, the frequency-mixing signals are highly collimated, with the emission direction and polarization controlled, respectively, by the pump frequencies and the rotation angle of WS 2 relative to the propagation direction of the guided waves. These results indicate that the rules of nonlinear frequency conversion are applicable even when the crystal is scaled down to the ultimate single-layer limit. This study provides a versatile platform to enhance the nonlinear optical response of 2D materials and favor the scalable generation of a coherent light source and entangled photon pairs.

Efficient Emission Outcoupling from Perovskite Lasers into Highly Directional and Long‐Propagation‐Length Bloch Surface Waves

“…Second, optimization of PC parameters leads to a superior light confinement and enhancement, [ 45 ] where the position of BSW field maximum can be arbitrary tuned inside the top layer of PC and adjusted to the PC–air interface. This opens up new possibilities of using the BSW platform in sensing [ 46 ] or optical trapping, [ 47 ] as well as for enhancing the interaction of light with the materials, which can be easily integrated with the BSW platform, for example, various ultra‐thin 2D materials [ 48–50 ] with high optical nonlinearities [ 51–54 ] and supporting exciton‐polaritons at room temperature. [ 50,55 ] Moreover, CsPbBr$${}_3$$‐based nano‐ and microlasers chemically tuned in broad spectral range [ 27,56 ] are prospective for spectrally adjusted in‐plane irradiation of the various objects and materials on PC surface.…”

Revealing the Competition between Defect‐Trapped Exciton and Band‐Edge Exciton Photoluminescence in Monolayer Hexagonal WS2

“…Monolayer transition-metal dichalcogenides (TMDs) have attracted tremendous interests due to their unique electronic or optical properties, i.e., direct bandgaps, [1] strong excitonic effects, [2,3] strong nonlinear effects, [4][5][6] and valley-pseudospin, [7][8][9] which has great potential for developing new optoelectronic and valleytronic devices. In TMDs, the most common defects like vacancy [10] and grain boundary [11] always act as chemical/physical adsorption sites [12][13][14] or scattering centers.…”

Broadband Plasmon-Enhanced Four-Wave Mixing in Monolayer MoS2

“…However, the applications of TMDs in nonlinear optics are limited due to the low conversion efficiency caused by the short light–matter interaction length at their atomic thickness. Several approaches have been proposed including plasmonics, − photonic cavities, and waveguide integration . Among them, plasmonics provides an excellent platform for enhancing light–matter interaction, which shows great potential for nanoscale nonlinear optical applications. − For example, the SHG of WS 2 on the silver nanogroove grating was enhanced by the plasmonic resonance, with a large enhancement factor (∼400) .…”