基于铌酸锂纳米晶体颗粒二次谐波发射特性研究

Second-harmonic generation based on single lithium niobate nanocrystals

基于纳米结构的二次谐波发射是构建高灵敏度生化传感器等纳光子器件的重要手段,其中如何获得增强的二次谐波发射是实现这些应用的关键.本文采用溶剂热法制备出类钻石的十二面体铌酸锂纳米晶体颗粒,实现了磁偶极共振模式的有效激发.基于磁偶极共振对入射场能量的聚焦作用,以及铌酸锂材料本身所具有的较强二阶非线性响应,所制备铌酸锂纳米晶体颗粒能够实现二次谐波的增强发射.不同粒径铌酸锂颗粒散射光谱及二次谐波发射光谱的测试结果表明,当激发光波长与纳米颗粒的磁偶极共振模式匹配时,可有效增强二次谐波发射强度,其非线性转换效率达到2.0×10^(-6)W^(-1).这些研究结果表明本文所制备的铌酸锂纳米晶体颗粒是一种较为理想的非线性纳米材料,在非线性纳光子器件的设计等领域具有潜在的应用价值.

Second-harmonic generation from nanostructures has been widely adopted to construct functional nanophotonic devices such as high-sensitivity biosensors,and realizing enhanced nonlinear conversion efficiency is important to improve device performance.In this study,diamond-like dodecahedral lithium niobate nanocrystals were fabricated via a solvothermal method,and the magnetic dipole resonances could be effectively excited.This way,the incident energy could be confined effectively within the nanoparticles.Combined with the strong intrinsic second-order nonlinear responses of the lithium niobate material,enhanced second-harmonic generation can be achieved with the fabricated nanocrystals.The experimental results showed that when the pump wavelength approached the magnetic resonance of the nanoparticles,the second-harmonic emission was strongly enhanced,and the nonlinear conversion efficiency was as large as 2.0×10-6W-1.The fabricated lithium niobate nanocrystals have great application potential for enhanced secondharmonic generation and the design of functional nonlinear nanophotonic devices.