Quantization of Mode Shifts in Nanocavities Integrated with Atomically Thin Sheets

Abstract

The unique optical properties of 2D layered materials are attractive for achieving increased functionality in integrated photonics. Owing to the van der Waals nature, these materials are ideal for integrating with nanoscale photonic structures. Here a carefully designed air‐mode silicon photonic crystal nanobeam cavity for efficient control through 2D materials is reported. By systematically investigating various types and thicknesses of 2D materials, the authors are able to show that enhanced responsivity allows for giant shifts of the resonant wavelength. With atomically precise thickness over a macroscopic area, few‐layer flakes give rise to quantization of the mode shifts. The dielectric constant of the flakes is extracted and found to be independent of the layer number down to a monolayer. Flexible reconfiguration of a cavity is demonstrated by stacking and removing ultrathin flakes. With an unconventional cavity design, these results open up new possibilities for photonic devices integrated with 2D materials.

Resonant exciton transfer in mixed-dimensional heterostructures for overcoming dimensional restrictions in optical processes

“…For the 2D material, WSe 2 is selected owing to its high stability at room temperature and a large bandgap that could offer sufficiently high energy excitons for transferring into CNTs. A WSe 2 flake is placed on top of the tubes by utilizing the anthracene-assisted transfer technique 26 , 27 . The CNT/WSe 2 heterostructures are therefore entirely free-standing as depicted in Fig.…”

“…For the purpose of stamping WSe 2 flakes onto CNTs, anthracene crystals are grown through an in-air sublimation process 26 , 27 . The procedure commences with the placement of anthracene powder onto a glass slide, which is subsequently heated to 80 °C.…”

“…This completely dry process eliminates the risk of contamination from solvent. Moreover, the solid single-crystal anthracene serves to shield the 2D flakes and the CNT throughout the transfer, ensuring that the CNT/WSe 2 heterostructure experiences minimal strain 26 , 27 . We note that some of the CNT/WSe 2 samples exhibit substantially small E 11 and E 22 energy shifts of less than 5 meV, suggesting a lack of contact between the CNT and the WSe 2 .…”

Self-Aligned Hybrid Nanocavities Using Atomically Thin Materials

“…The integration of 2D materials with nanophotonic architectures − offers a promising avenue to manipulate light–matter coupling, thereby facilitating the realization of hybrid devices such as lasers, − quantum emitters, , and photodetectors. ,, To achieve optimal device performance, it is imperative to couple 2D materials with cavities exhibiting a high quality factor over the mode volume ratio ( Q / V mode ). The planar air hole photonic crystal (PhC) nanocavities − promise strong light confining in an ultrasmall mode volume, rendering them highly attractive for the aforementioned hybrid device applications.…”

van der Waals Decoration of Ultra-High-Q Silica Microcavities for χ(2)–χ(3) Hybrid Nonlinear Photonics

“…Silica whispering-gallery microcavities boast ultrahigh Q values (>10 8 ) that ensure high-circulating optical intensities essential for inducing various optical nonlinear processes − with a moderate continuous-wave (CW) excitation. Meanwhile, monolayer TMDs possess a magnitude of second-order nonlinearity comparable to that of commonly used nonlinear crystals − and are thus expected to be used for practical nonlinear applications. − Their atomically thin nature gives them mechanical flexibility to conform to the surface of the optical microcavities, and the van der Waals character makes them compatible for the heterogeneous interface. − …”