Linear Electro-Optic Effect in 2D Ferroelectric for Electrically Tunable Metalens

Yuanda Liu, Yaze Wu, Ruihuan Duan, Jichao Fu, Martin Ovesen, Samuel Chang En Lai, Think E. Yeo, Jing Yee Chee, Yunjie Chen, Siew Lang Teo, Hui Ru Tan, Wang Zhang, Joel K.W. Yang, Kristian Sommer Thygesen, Zheng Liu, Yong Wei Zhang*, Jinghua Teng*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The advent of 2D ferroelectrics, characterized by their spontaneous polarization states in layer-by-layer domains without the limitation of a finite size effect, brings enormous promise for applications in integrated optoelectronic devices. Comparing with semiconductor/insulator devices, ferroelectric devices show natural advantages such as non-volatility, low energy consumption and high response speed. Several 2D ferroelectric materials have been reported, however, the device implementation particularly for optoelectronic application remains largely hypothetical. Here, the linear electro-optic effect in 2D ferroelectrics is discovered and electrically tunable 2D ferroelectric metalens is demonstrated. The linear electric-field modulation of light is verified in 2D ferroelectric CuInP2S6. The in-plane phase retardation can be continuously tuned by a transverse DC electric field, yielding an effective electro-optic coefficient rc of 20.28 pm V–1. The CuInP2S6 crystal exhibits birefringence with the fast axis oriented along its (010) plane. The 2D ferroelectric Fresnel metalens shows efficacious focusing ability with an electrical modulation efficiency of the focusing exceeding 34%. The theoretical analysis uncovers the origin of the birefringence and unveil its ultralow light absorption across a wide wavelength range in this non-excitonic system. The van der Waals ferroelectrics enable room-temperature electrical modulation of light and offer the freedom of heterogeneous integration with silicon and another material system for highly compact and tunable photonics and metaoptics.

Original languageEnglish
Article number2401838
JournalAdvanced Materials
Volume36
Issue number29
Number of pages11
ISSN0935-9648
DOIs
Publication statusPublished - 2024

Keywords

  • 2D ferroelectric
  • CuInPS
  • Electric-field
  • Metalens
  • Tunability

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