Sb2Te3 topological insulator: surface plasmon resonance and application in refractive index monitoring.

Topological insulators as new emerging building blocks in electronics and photonics present promising prospects for exciting surface plasmons and enhancing light-matter interaction. Thus, exploring the visible-range plasmonic response of topological insulators is significant to reveal their optical characteristics and broaden their applications at high frequencies. Herein, we report the experimental demonstration of a visible-range surface plasmon resonance (SPR) effect on an antimony telluride (Sb2Te3) topological insulator film. The results show that the SPR can be excited with a relatively small incident angle in the Kretschmann configuration based on the Sb2Te3 film. Especially, we develop an impactful digital holographic imaging system based on the topological insulator SPR and realize the dynamic monitoring of refractive index variation. Compared with the traditional SPR, the Sb2Te3-based SPR possesses a broader measurement range. Our findings open a new avenue for exploring the optical physics and practical applications of topological insulators, such as environmental and biochemical sensing.

Simultaneous measurement of refractive index distribution and topography by integrated transmission and reflection digital holographic microscopy.

We propose a method for simultaneously measuring dynamic changes of the refractive index distribution and surface topography, which integrates the transmission and reflection digital holographic microscopy based on polarization and angular multiplexing techniques. The complex amplitudes of the transmitted and reflected object waves can be simultaneously retrieved. The phase information of the reflected object wave is directly used to determine the topography of the specimen which corresponds to its physical thickness. Assuming that the refractive index distribution is uniform in the direction of the specimen thickness, the refractive index distribution can be deduced from the phase distributions of the transmitted and reflected object waves without any approximation. The refractive index distribution and dynamic changes of the topography of a tiny deionized water droplet have been measured for the availability of the proposed method.

Dual-wavelength common-path digital holographic microscopy for quantitative phase imaging based on lateral shearing interferometry.

A dual-wavelength common-path digital holographic microscopy based on a single parallel glass plate is presented to achieve quantitative phase imaging, which combines the dual-wavelength technique with lateral shearing interferometry. Two illumination laser beams with different wavelengths (λ1=532 nm and λ2=632.8 nm) are reflected by the front and back surfaces of the parallel glass plate to create the lateral shear and form the digital hologram, and then the hologram is reconstructed to obtain the phase distribution with a synthetic wavelength Λ=3339.8 nm. The experimental configuration is very compact, with the advantages of vibration resistance and measurement range extension. The experimental results of the laser-ablated pit, groove, and staircase specimens show the feasibility of the proposed configuration.