Role of hot electron scattering in epsilon-near-zero optical nonlinearity

Nanophotonics

article

Heng Wang¹  Ting Mei¹  Kang Du¹  Ruibin Liu²  Xinhai Dai¹  Wending Zhang¹  Soo Jin Chua¹ 

[1] MOE Key Laboratory of Material Physics and Chemistry Under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, School of Physical Science and Technology, Northwestern Polytechnical University;Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong;Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3;LEES Program, Singapore-MIT Alliance for Research & Technology (SMART)

关键词: electron scattering;    epsilon-near-zero;    free electron optical nonlinearity;    intraband transition;   

DOI  :  10.1515/nanoph-2020-0266

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

The physical origin of epsilon-near-zero (ENZ) optical nonlinearity lies in the hot-electron dynamics, in which electron scattering plays an important role. With the damping factor defined by hot electron scattering time, the Drude model could be extended to modeling ENZ optical nonlinearity completely. We proposed a statistical electron scattering model that takes into account the effect of electron distribution in a nonparabolic band and conducted the investigation on indium tin oxide (ITO) with femtosecond-pump continuum-probe experiment. We found that ionized impurity scattering and acoustic phonon scattering are the two major scattering mechanisms, of which the latter had been neglected before. They dominate at low-energy and high-energy electrons, respectively, and are weakened or boosted for high electron temperature, respectively. The electron energy–dependent scattering time contributed from multiple scattering mechanisms shows the electron density–dependent damping factor. The comprehensive understanding of electron scattering in ITO will help to develop a complete model of ENZ optical nonlinearity.

【 授权许可】

CC BY