# Enhanced Circular Dichroism by F-Type Chiral Metal Nanostructures

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## Abstract

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## 1. Introduction

## 2. Materials and Methods

## 3. Results and Discussion

#### 3.1. Spectral Properties of Circular Dichroism of Metal Nanostructures

#### 3.2. Effects of Metal Nanostructure Parameters on Chiral Properties

## 4. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) The unit schematic of F-type metallic hand-shaped nanostructures. (

**b**) The schematic for an array of F-type metallic hand-shaped nanostructures.

**Figure 2.**The transmission spectrum and CD spectrum of F—type metallic nanostructure: (

**a**) CD spectrum; (

**b**) transmission spectrum.

**Figure 3.**The figure shows the current density distribution at resonance (

**a**) the distribution of the RCP and LCP irradiated current density (Mode 1); (

**b**) the distribution of the RCP and LCP irradiated current density (Mode 2).

**Figure 4.**(

**a**) The unit schematic of metal nanostructures with different gaps. (

**b**) CD spectra of metallic nanostructures with different gaps.

**Figure 5.**The electric field intensity for the metal nanostructures with varying gaps (a = −20 nm (blue rectangle), a = 0 (red rectangle), and a = 20 nm (black rectangle)). (

**a**–

**f**) Electric field intensity in Mode 1. (

**g**–

**l**) Electric field intensity in Mode 2.

**Figure 6.**(

**a**) CD spectra of F−type metal chiral nanostructures at different tilt angles. (

**b**) Relationship between CD values and period and frequency ($f=c/\lambda $).

**Figure 7.**(

**a**) CD spectra of ${r}_{1}=100$ nm, ${r}_{2}=110$ nm, 100 nm, 90 nm; (

**b**) CD spectra of ${r}_{1}=110$ nm, 100 nm, 90 nm, ${r}_{2}=110$ nm.

**Figure 8.**(

**a**) CD spectra of arrays with the same unit cell but different periodicities. (

**b**) Transmittance relation to period and frequency.

Chiral Nanostructures | Optical Chirality | Wavelength Range (nm) | CD Value (%) | Reference |
---|---|---|---|---|

Crossed nanorods with nanowire | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 600–1000 | 0.18/−0.15 | [28] |

Twisted Z-shaped nanostructure(TZN) | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 500–1000 | 0.868 | [29] |

Nanoholes in mental film/Tilted nanorods | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 600–2000 | 0.12 | [30] |

Nanowire/G-type nanostructure | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 300–6000 | −0.309/0.44 | [31] |

Gold bilayer slit array/rectangular holes | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 400–3000 | 0.167 | [32] |

Nano slits milled in gold layer | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 600–800 | 0.95 | [33] |

F-type metal nanostructure | $CD={T}_{+}{}_{+}-{T}_{-}{}_{-}$ | 620–780 | −7.5/1.5 | this work |

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**MDPI and ACS Style**

Luo, Y.; Liu, J.; Yang, H.; Liu, H.; Zeng, G.; Huang, B.
Enhanced Circular Dichroism by F-Type Chiral Metal Nanostructures. *Photonics* **2023**, *10*, 1028.
https://doi.org/10.3390/photonics10091028

**AMA Style**

Luo Y, Liu J, Yang H, Liu H, Zeng G, Huang B.
Enhanced Circular Dichroism by F-Type Chiral Metal Nanostructures. *Photonics*. 2023; 10(9):1028.
https://doi.org/10.3390/photonics10091028

**Chicago/Turabian Style**

Luo, Yuyuan, Jin Liu, Haima Yang, Haishan Liu, Guohui Zeng, and Bo Huang.
2023. "Enhanced Circular Dichroism by F-Type Chiral Metal Nanostructures" *Photonics* 10, no. 9: 1028.
https://doi.org/10.3390/photonics10091028