Recent progresses and applications on chiroptical metamaterials: a review

Chiroptical metamaterials have attracted considerable attention owing to their exciting opportunities for fundamental research and practical applications over the past 20 years. Through practical designs, the chiroptical response of chiral metamaterials can be several orders of magnitude higher than that of natural chiral materials. Chiroptical metamaterials therefore represent a special type of artificial structures for unique chiroptical activities. In this review, we present a comprehensive overview of the progresses in the development of chiroptical metamaterials. Chiroptical metamaterial progress enables applications, including asymmetric transmission, polarization conversion, chiral absorber, chiral imaging, chiral sensor and chiral emission. We also review fabrication techniques and design of chiroptical metamaterials based on deep learning. In the conclusion, we present possible further research directions in this field.