Observation of coupling interaction between surface plasmons and Tamm plasmons.

The optical effect analogous to electromagnetically induced transparency (EIT) in atomic systems has attracted broad attention in the field of photonics due to its promising applications in optical storage and integrated devices. Herein, we firstly report the experimental observation of the EIT-like effect generated from the coupling between surface plasmons (SPs) and Tamm plasmons (TPs) in a hybrid multilayer system at the near-infrared band. This multilayer system is composed of a nanofabricated silver grating on a silver/Bragg mirror with a SiO2 spacer. The experimental results show that a narrow reflection peak can appear in the wide reflection spectral dip due to the coupling between the SPs in the silver grating and TPs in the silver/Bragg mirror, which agree well with the finite-difference time-domain (FDTD) simulations. It is also found that the dip position of the EIT-like spectrum presents a redshift with the increase of the silver grating width. These results will provide a new way, to the best of our knowledge, for the generation of the EIT-like effect and light spectral manipulation in multilayer structures.

Strong enhancement of third harmonic generation from a Tamm plasmon multilayer structure with WS2.

Improving the conversion efficiency is particularly important for the generation and applications of harmonic waves in optical microstructures. Herein, we propose to enhance the efficiency of third harmonic generation by integrating a monolayer WS2 with the metal/dielectric/photonic crystal multilayer structure. The numerical simulations show that the multilayer structure enables to generate the Tamm plasmon mode between the metal film and photonic crystal around the telecommunication wavelength, which is consistent with the experimental result. By measuring with a self-built nonlinear optical micro-spectroscopy system, we find that the third harmonic signal can be reinforced by 16-fold through inserting the monolayer WS2 in the dielectric spacer. This work will provide a new way for improving nonlinear optical response, especially THG in multilayer photonic microstructures.

Guided wave resonance-based digital holographic microscopy for high-sensitivity monitoring of the refractive index.

Surface plasmon resonance holographic microscopy (SPRHM) has been employed to measure the refractive index but whose performance is generally limited by the metallic intrinsic loss. Herein we first, to our knowledge, utilize guided wave resonance (GWR) with low loss to realize the monitoring of the refractive index by integrating with digital holographic microscopy (DHM). By depositing a dielectric layer on a silver film, we observe a typical GWR in the dielectric layer with stronger field enhancement and higher sensitivity to the surrounding refractive index compared to the silver film-supported SPR, which agrees well with calculations. The innovative combination of the GWR and DHM contributes to the highly sensitive dynamic monitoring of the surrounding refractive index variation. Through the measurement with DHM, we found that the GWR presents an excellent sensitivity, which is 2.6 times higher than that of the SPR on the silver film. The results will pave a new pathway for digital holographic interferometry and its applications in environmental and biological detections.