He Weixin, Chen Changjiang, Wu Shiyao, Wong Walter P D, Wu Zhenyue, Chang Kai, Wang Jiesu, Gao Heng, Loh Kian Ping
Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.
Department of Physics, National University of Singapore, Singapore 117551, Singapore.
J Am Chem Soc. 2025 Jan 8;147(1):811-820. doi: 10.1021/jacs.4c13604. Epub 2024 Dec 19.
Electrically switchable second harmonic generation (SHG) is highly valuable in electro-optic modulators, which can be deployed in data communication and quantum optics. Coupling circular dichroism (CD) with an electrically controlled SHG process is advantageous because it enhances the signal transmission bandwidth and security while enabling multiple modulation modes for optical logic. However, ferroelectrically switchable chiral second-order nonlinearity is rarely reported. Here, we demonstrate the electro-optic modulation of SHG based on the multipolar effect in a chiral ferroelectric two-dimensional hybrid perovskite -(FBDA)CdCl (-FBDA = (2)-2-fluorobutane-1,4-diamine). -(FBDA)CdCl (-FCC) crystals are highly stable in air, and its SHG response exhibits circular dichroism (i.e., SHG-CD) that can be ferroelectrically switched. The ferroelectrically switchable SHG-CD arises from the reconfiguration of distinct chirality-induced multipolar moments during the ferroelectric switching process. This reconfiguration induces a π/2 circular difference in SHG, leading to a reversal of circularly polarized light sensitivity. As a proof of concept, we demonstrate that the electrically controlled SHG-CD of -FCC can be used in the transmission of encrypted optical communications.
电可切换二次谐波产生（SHG）在电光调制器中具有很高的价值，电光调制器可应用于数据通信和量子光学领域。将圆二色性（CD）与电控SHG过程相结合具有优势，因为它可以提高信号传输带宽和安全性，同时实现光逻辑的多种调制模式。然而，铁电可切换手性二阶非线性却鲜有报道。在此，我们展示了基于手性铁电二维混合钙钛矿 -（FBDA）CdCl（-FBDA = （2）-2-氟丁烷-1,4-二胺）中的多极效应实现的SHG电光调制。-（FBDA）CdCl（-FCC）晶体在空气中高度稳定，其SHG响应表现出可通过铁电切换的圆二色性（即SHG-CD）。铁电可切换的SHG-CD源于铁电切换过程中不同手性诱导的多极矩的重新配置。这种重新配置会在SHG中产生π/2的圆差，导致圆偏振光灵敏度的反转。作为概念验证，我们证明了-FCC的电控SHG-CD可用于加密光通信的传输。
