多波长飞秒激光激发下GaAs纳米线SHG特性研究

摘要

The nonlinear optical properties of semiconductor nanowires are of vital importance in the researches of nano-optics and fabri-cation of nano-scale optoelectronic components. GaAs is a direct bandgap semiconductor material of wide bandgap, high electron mobility, large χ(2), high laser damage threshold and stable chemical properties, all of which make it a potential nonlinear optical material. In this report, based on the finite element method (FEM), we investigated the optical response and local field enhancement of GaAs nanowires perpendicular to the GaAs substrate surface. Under the radiation of femto-second laser pulses at different wave-lengths, efficient second harmonic generation (SHG) signal was acquired from the nanowires. Furthermore, noise-free broadband SHG signal was also detected to be excitated by super-continuous femto-second pulses (1000–1300 nm). The high-efficiency SHG process could be attribated mainly to the local field enhancement effect of the nanowires. Our investigation is the first, as far as we know, demonstrate the SHG properties of GaAs nanowires, and the results suggest that GaAs nanowires are promising in the potential applications in nano-scale optical devices, integrated nanophotonic circuits, from which related nano-optics researches can benefit.%　　本文基于有限元法研究了直立生长于GaAs衬底的GaAs纳米线的光场响应和光场增强性质。实验使用多个波长的飞秒激光脉冲激发GaAs纳米线，测得了较高效率的二次谐波信号，并首次使用宽带超连续飞秒脉冲(1000—1300 nm)在纳米线上获取了宽带、无杂散荧光噪声的二次谐波信号。这种高效的二次谐波产生过程主要归因于纳米结构引起的局域场增强效应。本文阐明了GaAs纳米线的二次谐波倍频特性，这些结果对于其在纳米光学中的光器件、光集成等领域的进一步研究和实际应用具有很好的参考价值。