Tunable Optical Rotation in Twisted Black Phosphorus

Abstract

Black phosphorus (BP) is a typical two-dimensional (2D) layered material with strong in-plane anisotropy and large birefringence, making it possible to manipulate the light field with atomically controlled devices for various optoelectronic and photonic applicationsfor instance, atomic thickness waveplates. The twist angle in twisted black phosphorus (TBP) can be presented as a new tunable dimension to control BP's optical anisotropy. Here, we report a large and tunable optical rotation effect in TBP, the result of regulating the twist angle and BP thickness. To accurately study the optical rotation and the impact of the twist angle, we developed a new method to prepare TBP. A lab-made polarimeter microscope was used to visualize the optical rotation mapping of TBP. A large polarization-plane rotation (PORA) of 0.49°per atomic layer was observed from an air/BP/ SiO 2 /Si Fabry−Peŕot cavity at 600 nm, an order of magnitude higher than the PORA of 0.05°per atomic layer reported earlier. For the same thickness, the PORA of TBP can be tuned from 0.48°to 7.75°based on the twist angle from 0°to 90°. Our work provides an efficient method to investigate the anisotropy of 2D materials and their heterojunctions. TBP could help us design novel optical and optoelectronic devices such as tunable nanoscale polarization controllers.

Reconfigurable and Broadband Polarimetric Photodetector

“…Under a parallel configuration, both A 1 g and B 1 g modes exhibit a periodicity of 180 o , the 0 0 (or 180 o ) at which the intensities reach minimum is corresponding to the zigzag direction of b‐As 0.4 P 0.6 crystal, while the 90 0 (or 270 o ) is along the armchair direction. [ 20–21,26–27 ] The data can be well fitted using the formula described in Experimental Section. The polarization angles dependent phonon modes indicate the in‐plane anisotropic structure and can determine the lattice orientation of the b‐As 0.4 P 0.6 flake.…”

Engineering van der Waals Materials for Advanced Metaphotonics

“…With these unique layer-and angule-dependent absorption effects, tunable optical rotation of incident light was realized by adjusting the layer numbers and stacking angles recently. 185 The light responses can also be altered by introducing strain to the BP layer, since the energy band structure of BP is known to be vulnerable to strain-induced deformation in molecular structures, as we discussed previously. In 2018, Xie et al 158 presented a simulation of reflectivity and absorption of light for monolayer BP under both tensile and compressive biaxial strain.…”

“…Apparently, lower transmission and reflection are achieved over a broader band of light along the armchair direction compared to zigzag direction, which thereafter translated into much larger absorption and much stronger light–matter interaction along the armchair direction. With these unique layer- and angule-dependent absorption effects, tunable optical rotation of incident light was realized by adjusting the layer numbers and stacking angles recently . The light responses can also be altered by introducing strain to the BP layer, since the energy band structure of BP is known to be vulnerable to strain-induced deformation in molecular structures, as we discussed previously.…”

A Black Phosphorus‐Based Fabry–Pérot Cavity and Its Application for Reversible Color Switching

“…[ 47 ] However, the relatively weak strength of BP optical anisotropy in the visible region forbids its applications in the sectors in which polarization‐dependent, integrated, and nanoscale polarization controllers are desired. [ 45,48 ] Robust in‐plane optical anisotropy of the atomic layer and ultrathin BP laminate provides a perspective of new devices. It excites increasing explorations and interest, where an enhancement of optical anisotropy is necessary.…”