摘要
氧化铟锡(ITO)薄膜作为主流透明导电氧化物(TCO),具有载流子浓度高、易掺杂以及在其近零介电常数(ENZ)区域可引发极大的非线性光学响应、局域电场增强、慢光效应等独特性质,在非线性光学材料研究中受到广泛关注。本文阐述了ITO薄膜的应用场景、导电机理,以及ENZ非线性光学基础和表征技术;综述了厚度调控、缺陷诱导、材料复合、微结构构建等对非线性光学调制产生影响的研究进展;展望了其在全光调制、光限幅以及量子信息处理、生物医学成像等新兴领域的拓展潜力。
Significance Nonlinear optics primarily investigates nonlinear phenomena occurring in materials under intense light irradiation,along with their theoretical underpinnings and applications.This field originated from the discoveries of the Pockels effect and the Kerr effect.The advent of lasers has provided high-intensity,highly coherent light beams essential for nonlinear optical research,thereby accelerating its development.Today,this field plays a pivotal role in modern photonic functional devices and systems,with extensive applications in optical communications,all-optical information processing and storage,spectroscopy,and quantum information technology.The broad application prospects of nonlinear optical technologies highlight the significance of advanced nonlinear optical materials.Meanwhile,advances in material processing and micro/nanofabrication techniques have facilitated the emergence of diverse new materials and structures suitable for nonlinear optics.These innovations continuously provide new platforms,mechanisms,and methods for generating and manipulating nonlinear optical effects,driving the vigorous development of the field.Research has shown that materials and structures with near-zero electromagnetic parameters—such as near-zero permittivity,near-zero permeability,and near-zero refractive index—often exhibit novel optical properties.The optical functionality of a material is inherently associated with its dielectric constant.Structures with a near-zero dielectric constant(epsilon-near-zero,ENZ)display unique optical characteristics,such as ultrafast phase velocities of propagating light,coupled with exceptionally strong nonlinear optical responses.The remarkable linear and nonlinear optical properties of ENZ structures open up entirely new avenues for the design of integrated optical devices.Indium tin oxide(ITO)films,as a mainstream transparent conductive oxide(TCO),possess high carrier concentration,ease of doping,and unique properties in their ENZ region,including a significant nonlinear optical response,localized electric field enhancement,and photoelectric effects.These features distinguish ITO films among materials studied in nonlinear optics research.This paper elaborates on the application scenarios and electrical conduction mechanisms of ITO films,as well as the fundamentals and characterization techniques of ENZ nonlinear optics.It reviews the research progress on nonlinear optical modulation regulated by thickness tuning,defect engineering,material compositing,and microstructure construction.Furthermore,it explores the expansion potential of ITO in emerging fields such as all-optical modulation,optical limiting,quantum information processing,and biomedical imaging.Progress Alam et al.discovered that ITO exhibits excellent nonlinear optical properties in its ENZ region,achieving a remarkable 170%change in linear refractive index with a recovery time of only~360 fs(Fig.1).This research has attracted considerable attention in the scientific community.Fig.5 illustrates the effect of thickness-dependent loss in ITO on the ENZ-enhanced optical response for both single-layer ITO and ITO/SiO2 multilayer stack structures.Fig.6 depicts the factors influencing nonlinear optical modulation in ITO-Sn composite films with different stoichiometric ratios.Fig.7(a)shows the real(solid line)and imaginary(dotted line)parts of the dielectric constant of ITO films before and after annealing.The inset presents λ as a function of annealing temperature.Fig.7(b)displays the real(solid line)and imaginary(dotted line)parts of the dielectric constant of ITO films before and after laser irradiation.Fig.7(c)shows the Raman spectra of graphene oxide(GO),ITO films,and ITO/GO composites,with an inset illustrating the Raman spectra of GO at different thicknesses.Fig.7(d)depicts the open-aperture Z-scanning fitting curves for GO,ITO,and ITO/GO composites.Fig.8 presents the normalized openaperture Z-scanning curves of Zn-based nanostructures with different Ni proportions under continuous-wave excitation.Fig.9 demonstrates tunable ENZ and nonlinear saturated absorption achieved by metal-dielectric composite films.Fig.10 shows the tunable ENZ and nonlinear saturated absorption of ITO/polyvinyl alcohol(PVA)composite films.Fig.11 illustrates tunable nonlinear optics realized by integrating ITO films with semiconductor composite films.Fig.12 presents tunable ENZ and nonlinear optics achieved via TiN/ITO composite structures.Fig.13 demonstrates the tunability of nonlinear optics enabled by laser-induced ITO microstructures.The intensity modulation capability of the device at 1450 nm is shown in Fig.14.Fig.15 illustrates an antennaintegrated ITO nonlinear metasurface structure.Conclusions and Prospects This study focuses on ITO thin-film ENZ photonics,exploring the effects of factors such as electrical conduction mechanisms,thickness effects,defects,metal-semiconductor composites,and microstructures on nonlinear optical properties.The series of findings provides a solid theoretical basis and technical support for designing nonlinear optical devices such as optical switches and optical limiters.Despite significant progress in this field,further research is required at the fundamental theoretical level to deepen the understanding of nonlinear optical modulation mechanisms in different microstructures and composite systems,as well as their behaviors under extreme conditions.At the experimental technology level,challenges in the precise control of fabrication processes and microstructure construction must be addressed,and efficient characterization techniques developed.In terms of application expansion,breakthroughs are needed to overcome the limitations of existing devices,explore applications in quantum information processing and biomedical imaging,and achieve intelligent control through integration with artificial intelligence technologies.With continuous research and technological innovation,ITO-film-based ENZ photonics is expected to advance nonlinear optical modulation techniques and related fields such as optical communications and quantum information processing,demonstrating broad application prospects and significant potential value.
作者
刘涛
颜廷贞
洪瑞金
陶春先
张大伟
Liu Tao;Yan Tingzhen;Hong Ruijin;Tao Chunxian;Zhang Dawei(Engineering Research Center of Optical Instrument and System,Ministry of Education and Shanghai Key Lab of Modern Optical System,University of Shanghai for Science and Technology,Shanghai 200093,China;Department of Printing and Pack Aging Engineering,Shanghai Publishing and Printing College,Shanghai 200093,China)
出处
《光学学报(网络版)》
2026年第3期75-91,共17页
Acta Optica Sinica(Online)
基金
国家自然科学基金(62275159,62505179)
上海市教育委员会上海市教育发展基金会“晨光计划”(23CGB10)。
关键词
非线性光学
氧化铟锡薄膜
近零介电常数
饱和吸收
Z扫描技术
nonlinear optics
indium tin oxide thin films
near-zero dielectric constant
saturation absorption
Z-scanning technique
