Sub-picosecond,strain-tunable,polarizationselective optical switching via anisotropic exciton dynamics in quasi-1D ZrSe_(3)  

作　　者：Sang Ho Suk Sanghee Nah Muhammad Sajjad Sung Bok Seo Jianxiang Chen Sangwan Sim 

机构地区：[1]School of Electrical Engineering,Hanyang University,Ansan,South Korea [2]Seoul Center,Korea Basic Science Institute,Seoul,South Korea [3]Nottingham Ningbo China Beacons of Excellence Research and Innovation Institute,University of Nottingham,Ningbo,China [4]Key Laboratory of Carbonaceous Wastes Processing and Process Intensification Research of Zhejiang Province,University of Nottingham Ningbo China,Ningbo,China

出　　处：《Light(Science & Applications)》2024年第11期2576-2588,共13页光（科学与应用)（英文版）

基　　金：supported by the National Research Foundation of Korea(NRF)through the government of Korea(MSIP)(Grant NRF-2022R1C1C1003124);funded by grants from the National Research Foundation of Korea(2022M3H9A2096197);the Korea Basic Science Institute(A439200).

摘　　要：In cutting-edge optical technologies,polarization is a key for encoding and transmitting vast information,highlighting the importance of selectively switching and modulating polarized light.Recently,anisotropic two-dimensional materials have emerged for ultrafast switching of polarization-multiplexed optical signals,but face challenges with low polarization ratios and limited spectral ranges.Here,we apply strain to quasi-one-dimensional layered ZrSe_(3)to enhance polarization selectivity and tune operational energies in ultrafast all-optical switching.Initially,transient absorption on unstrained ZrSe_(3)reveals a sub-picosecond switching response in polarization along a specific crystal axis,attributed to shifting-recovery dynamics of an anisotropic exciton.However,its polarization selectivity is weakened by a slow non-excitonic response in the perpendicular polarization.To overcome this limitation,we apply strain to ZrSe_(3)by bending its flexible substrate.The compressive strain spectrally decouples the excitonic and nonexcitonic components,doubling the polarization selectivity of the sub-picosecond switching and tripling it compared to that in the tensile-strained ZrSe_(3).It also effectively tunes the switching energy at a shift rate of~93 meV%-1.This strain-tunable switching is repeatable,reversible,and robustly maintains the sub-picosecond operation.First-principles calculations reveal that the strain control is enabled by momentum-and band-dependent modulations of the electronic band structure,causing opposite shifts in the excitonic and non-excitonic transitions.Our findings offer a novel approach for high-performance,wavelength-tunable,polarization-selective ultrafast optical switching.

关 键 词：POLARIZATION TUNABLE STRAIN 

分 类 号：O436.3[机械工程—光学工程]