Two-dimensional layered materials are considered ideal platforms to study novel small-scale optoelectronic devices due to their unique electronic structures and fantastic physical properties. However, it is urgent to further improve the light–matter interaction in these materials because their light absorption efficiency is limited by the atomically thin thickness. One of the promising approaches is to engineer the plasmonic environment around 2D materials for modulating light–matter interaction in 2D materials. This method greatly benefits from the advances in the development of nanofabrication and out-plane van der Waals interaction of 2D materials. In this paper, we review a series of recent works on 2D materials integrated with plasmonic environments, including the plasmonic-enhanced photoluminescence quantum yield, strong coupling between plasmons and excitons, nonlinear optics in plasmonic nanocavities, manipulation of chiral optical signals in hybrid nanostructures, and the improvement of the performance of optoelectronic devices based on composite systems.

Vacuum ultraviolet (VUV) light plays a crucial role in various scientific and technological fields, such as nanolithography and biomedical treatments. However, the inherent nonlinear optical coefficient of nonlinear optical crystals is typically very low, and increasing the action length is often necessary to improve the nonlinear conversion efficiency. This makes it challenging for these materials to achieve high-density optoelectronic integration at the micro-/nano-scale. In this study, we propose a design for generating coherent VUV radiation close to 175 nm using second harmonic generation (SHG) with an absolute efficiency exceeding 1.2‰ mW−1. This is achieved by merging multiple bound state in the continuum modes in a free-standing photonic crystal slab. Even with fabrication imperfections at a level lower than 10% disorder, the SHG efficiency of the samples remains robust, maintaining an efficiency of at least 2‰. This research provides a beneficial platform for generating efficient VUV light in the nanoscale.

Transition metal phosphorus sulfides (MPS₃), a family of two-dimensional magnetic materials with a van der Waals structure, exhibit promising applications in nonlinear optical devices. The emergence of carrier coherence in MPS₃ is a fascinating topic in coherently controlling the nonlinear effect (or other novel phenomena). Herein, we systematically investigated the third-order nonlinear optical responses of MPS₃ (M = Ni, Fe, Mn) flake suspensions based on spatial self-phase modulation (SSPM) effect. The effective monolayer third-order nonlinear susceptibilities (χ_monolayer⁽³⁾) of NiPS₃ and MnPS₃ are obtained for the first time at multiple wavelengths. Our results show that NiPS₃ has a higher χ_monolayer⁽³⁾ value (3.59 × 10⁻⁹ e.s.u. or 5.01 × 10⁻¹⁷ m²V^-2 at 405 nm excitation) than those of FePS₃ and MnPS₃. Furthermore, we laser-induced non-local hole coherence in MPS₃ based on SSPM, where the origin of excited-state holes is analyzed from electronic structures. The relationships between hole mobility μ_hole, effective mass m _h ^∗, and χ_monolayer⁽³⁾ for the three materials fulfill the previous investigation results. Because laser-induced hole coherence has rarely been reported, our investigation enriches the coherent regulation of two-dimensional magnetic MPS₃ materials, enabling potential applications in all-optical devices.

In optoelectronics and photonics, developing multifunctional light-emitting devices has become a prominent research area. However, achieving integration of polarization control, intensity modulation, and tunability within a single device presents a formidable challenge. Here, we report the design and implementation of a symmetric bound state in the continuum (BIC) realized by a metasurface composed of perovskite nanobars on a silica substrate. Through the incorporation of both in-plane and out-of-plane symmetries, the BIC undergoes a transformation into a chiral quasi-bound state in the continuum (q-BIC). The chiral q-BIC metasurface exhibits an intrinsic chiral response, characterized by nearly perfect circular dichroism of 0.96, a key property for chiral optical applications. Furthermore, the integration of Sb2S3 phase-change materials into the metasurface enables dynamic regulation of resonant circularly polarized emission wavelengths between 760 and 820 nm, with selective enhancement of right circularly polarized emission by 240-fold and suppression of left circularly polarized emission. Our chiral q-BIC metasurface enables single-device multi-function integration, offering a versatile and dynamically tunable platform for enhanced chiral optical responses across optoelectronics and photonics.

Magnetic Fano resonance provides a potential opportunity to control both linearity and nonlinearity of light for their low radiation loss and near-field enhancement. Previous investigations have demonstrated its significant enhancement of nonlinearity in a plasmonic structure and the 2D materials coupled to it. In this work, the enhancement of second harmonic generation (SHG) of hybrid bismuth halides at the important communication wavelength of 1550 nm with a magnetic Fano dip is theoretically studied. To this end, a hybrid system composed of two asymmetric silver square split rings (SSRs) and this chiral perovskite film is designed. The simulation results show that magnetic Fano-like resonance is induced at the destructive interface of two magnetic modes in the SSR dimer, which can be inherited to hybrid bismuth halides, thereby leading to the increase of four orders of magnitude in its SH near-field enhancement factor. With a peak intensity of 0.16 GW cm⁻², the composite structure features a high SHG conversion efficiency of up to 1.6 × 10⁻³ at the Fano resonance position. By rotating the polarization angle of fundamental optical excitation, the emitted SHG signal is switched on–off. Our research provides a valuable thought for enhancing the nonlinear optical process of the perovskite films by coupling the magnetic modes.