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A tunable fiber optic (FO) long‐range surface plasmon (LRSP) sensor with strong coupling is developed and demonstrated theoretically in this article. The sensor consists of a square lattice array of Ag nanodisks resting on the FO end face. Utilizing nanodisks with small diameters leads to the pronounced excitation of two distinct and independent resonant modes: surface plasmon polaritons (SPP) and LRSP. A systematic investigation is performed to evaluate the sensing performance and capabilities of the sensor, focusing on its bulk and surface sensitivity. Significantly, the LRSP mode demonstrates high sensitivity and favorable linearity in response to refractive index (RI) changes, with an exceptionally high figure of merit (FOM). On the contrary, the SPP mode is regarded as an ideal self‐referencing mode due to its immunity to RI fluctuations. The enlargement of nanodisks diameters results in a swift redshift in the LRSP wavelength, leading to a strong coupling with the SPP mode. This coupling facilitates the transfer of electric fields within the SPP mode, promotes sensing capabilities, and enables the realization of dual‐channel sensing functionality. The occurrence of strong coupling phenomena along with the use of FO substrates provides an innovative option for achieving multifunctionality and miniaturization in sensor platforms. [ABSTRACT FROM AUTHOR]

In recent years, constructing van der Waals (vdW) heterostructures based on different 2D materials has been a highly effective way to obtain desired electronic and optical properties. Herein, on the basis of first‐principles calculations, a 2D vdW heterostructure is constructed by vertically stacking the indirect‐bandgap gallium nitride (GaN) and silicane (SiH) monolayers. For the formed heterostructure, the structural, electronic, and optical properties are all computed. The obtained results show that the heterostructure is a direct‐bandgap semiconductor with typical type‐II band alignment. Furthermore, the linearly tunable bandgap, together with the robust type‐II band alignment, can be realized by applying vertical strains or external electric fields. It is also found that both monolayers exhibit the same UV absorption range and the notably enhanced UV absorption is obtained after forming the heterostructure. In particular, the maximum absorptivity can reach to 21.6%. These results are expected to provide useful references for the design of ultraviolet optoelectronic devices based on the 2D GaN/SiH vdW heterostructure. [ABSTRACT FROM AUTHOR]