Gap‐Plasmon Coupled Nanopillar Array to Promote Upconversion Luminescence

Abstract

This work theoretically explored the well-defined nanogap arranged as an upconversion (UC)/gold capping layer photonic nanopillar array on a back-reflecting film-coated Si substrate. The gap-plasmon (GP)-coupled periodic nanopillar array with encapsulating the upconversion layer (denoted as GPNA) is suggested to promote the upconversion luminescence (UCL) intensity at excitation and emission wavelengths. The optical localized-plasmon properties of the GPNA platform were probed by finite-difference time-domain (FDTD) method. With tweaking the geometric design parameters such as a cap thickness and gap distance, the GPNA platform can induce a prominent GP mode between the UC cap layer, thus leading to the significant plasmon-driven optical electromagnetic field amplification within the UC layer followed by substantial light absorption and UCL promotion. This proposed GP-coupled nanopillar array would pave the alternative way for a broad range of plasmon-sensitized applications which are able to absorb the incident excitation and resultant emission light.