posted on 2023-01-12, 15:08authored byFenglian Qi, Lin Li, Zhiwei Li, Lili Qiu, Zihui Meng, Yadong Yin
Chiral plasmonic nanostructures have promising applications
in
optoelectronics due to their chiroptical responses. However, achieving
active tuning of optical chirality remains challenging. Here, we develop
stretchable chiroptical films with mechanically tunable extrinsic
chirality by assembling hexagonal magnetic/plasmonic hybrid nanodisks
in magnetic fields. The nanodisks, synthesized using a space-confined
growth method, display three distinct plasmonic resonance modes at
the UV–vis–NIR region, which red shift with increasing
size as demonstrated by simulation and experimental results. The coupled
magnetic and plasmonic anisotropy allows convenient control over the
plasmonic resonance modes by altering the strength or direction of
external magnetic fields. Further, magnetically aligning the nanodisks
in a stretchable polymer film produces superstructures with extrinsic
chirality, displaying selective absorption of circularly polarized
light and inverted circular dichroism due to the linear dichroism-linear
birefringence effect. Reversible mechanical stretching allows for
continuous switching of circular dichroism in a wide range (from −1°
to +1°). The efficient magnetic alignment of hybrid nanodisks
in the hydrogel provides a simple and effective strategy for designing
stretchable optical devices with tunable extrinsic chirality.