In the broad spectral range, near‐infrared (NIR) plasmonics find applications in telecommunication, energy harvesting, sensing, and more, all of which would benefit from an electrostatically controllable NIR plasmon source. However, it is difficult to control bulk NIR plasmonics directly with electrostatics because of the strong electric‐field screening effect and high carrier concentration required to support NIR plasmons. Here, this constraint is overcome and the observation of NIR plasmonic resonances that can be modulated electrostatically over a range of ≈360 cm–1 in few‐layer NbSe2 gratings is reported, thanks to the enhanced electrostatics of atomically thin 2D materials and the high‐quality film produced by a solution method. NbSe2 plasmons also render strong field confinement due to their atomic thickness and provide an extra degree of resonance frequency modulation from the layered structure. This study identifies metallic 2D materials as promising (easily produced and well‐performing) candidates to extend electrostatically tunable plasmonics to the technologically important NIR range.

Optical wavefront engineering has been rapidly developing in fundamentals from phase accumulation in the optical path to the electromagnetic resonances of confined nanomodes in optical metasurfaces. However, the amplitude modulation of light has limited approaches that usually originate from the ohmic loss and absorptive dissipation of materials. Here, an atomically thin photon-sieve platform made of MoS 2 multilayers is demonstrated for high-quality optical nanodevices, assisted fundamentally by strong excitonic resonances at the band-nesting region of MoS 2 . The atomic thin MoS 2 significantly facilitates high transmission of the sieved photons and high-fidelity nanofabrication. A proof-of-concept two-dimensional (2D) nanosieve hologram exhibits 10-fold enhanced efficiency compared with its non-2D counterparts. Furthermore, a supercritical 2D lens with its focal spot breaking diffraction limit is developed to exhibit experimentally far-field label-free aberrationless imaging with a resolution of ∼0.44λ at λ = 450 nm in air. This transition-metal-dichalcogenide (TMDC) photonic platform opens new opportunities toward future 2D metaoptics and nanophotonics.

In this paper, we show enhanced photodynamic therapy and fluorescence imaging using cationic porphyrin photosensitizer TMPyP loaded gold nanorods in 2D monolayer cultures and a novel in vitro head and neck squamous cell carcinoma 3D model.

The inherent thinness of two-dimensional 2D materials limits their efficiency of light-matter interactions and the high loss of noble metal plasmonic nanostructures limits their applicability. Thus, a combination of 2D materials and plasmonics is highly attractive. This review describes the progress in the field of 2D plasmonics, which encompasses 2D plasmonic materials and hybrid plasmonic-2D materials structures. Novel plasmonic 2D materials, plasmon-exciton interaction within 2D materials and applications comprising sensors, photodetectors and, metasurfaces are discussed.

Excitonic resonance in atomically thin semiconductors offers a favorite platform to study 2D nanophotonics in both classical and quantum regimes and promises potentials for highly tunable and ultra‐compact optical devices. The understanding of charge density dependent exciton‐trion conversion is the key for revealing the underlaying physics of optical tunability. Nevertheless, the insufficient and inefficient light‐matter interactions hinder the observation of trionic phenomenon and the development of excitonic devices for dynamic power‐efficient electro‐optical applications. Here, by engaging an optical cavity with atomically thin transition metal dichalcogenides (TMDCs), greatly enhanced exciton‐trion conversion is demonstrated at room temperature (RT) and achieve electrical modulation of reflectivity of ≈40% at exciton and 7% at trion state, which correspondingly enables a broadband large phase tuning in monolayer tungsten disulfide. Besides the absorptive conversion, ≈100% photoluminescence conversion from excitons to trions is observed at RT, illustrating a clear physical mechanism of an efficient exciton‐trion conversion for extraordinary optical performance. The results indicate that both excitons and trions can play significant roles in electrical modulation of the optical parameters of TMDCs at RT. The work shows the real possibility for realizing electrical tunable and multi‐functional ultra‐thin optical devices using 2D materials.

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We present a general optimization technique for surface plasmon resonance, (SPR) yielding a range of ultrasensitive SPR sensors from a materials database with an enhancement of ∼100%. Applying the algorithm, we propose and demonstrate a novel dual-mode SPR structure coupling SPP and a waveguide mode within GeO2 featuring an anticrossing behavior and an unprecedented sensitivity of 1364 deg/RIU. An SPR sensor operating at wavelengths of 633 nm having a bimetal Al/Ag structure sandwiched between hBN can achieve a sensitivity of 578 deg/RIU. For a wavelength of 785 nm, we optimized a sensor as a Ag layer sandwiched between hBN/MoS2/hBN heterostructures achieving a sensitivity of 676 deg/RIU. Our work provides a guideline and general technique for the design and optimization of high sensitivity SPR sensors for various sensing applications in the future.