Fabrication and microanalysis of 3D-shell-like chiral nanostructure based on micro-sphere assembled technology

Abstract

Artificial chiral nanostructures have attracted many attentions for their unusual properties, such as giant chiroptical effect, the ability to achieve negative index and repellent Casimir force. However, their complicated geometrical morphologies usually require high-cost, inefficient fabrication technologies, especially for the chiral nanostructures working in the visible band. In this paper, we discuss a simple, low-cost and high-efficient fabrication method for the fabrication of high performance 3D shell like chiral nanostructure (SLCS). Through single material deposition on the self-assembled microsphere array monolayer, the 3D SLCS can be successfully formed. The spectral analysis of SLCS in microdomains show that the maximum circular dichroism (CD) signal can reach to about 9°, although the CD signal in bulk samples is very weak. The in-depth shadow effect analysis reveals that both of the left-hand and right-hand SLCS are formed in one sample, which generate CD signal of opposite signs, and weaken the chiroptical effect of bulk samples. Finite difference time domain method has been used to simulate the electromagnetic properties of SLCS located on micro-sphere array. Four typical SLCS with φ=0°, 15°, 30° and 45° has been analyzed and the simulated results meet well with the experiment. The SLCS with giant chiroptical effect will find potential applications in integrated photonics, enantiomer sensor and so on.